AssessmentoftheTrophicStatusoftheSouthLagoonof Tunis ...

Research ArticleAssessment of the Trophic Status of the South Lagoon ofTunis (Tunisia Mediterranean Sea) Geochemical andStatistical Approaches

Myriam Abidi Rim Ben Amor and Moncef Gueddari

RU Geochemistry and Environmental Geology Department of Geology Faculty of Sciences of TunisUniversity of Tunis El Manar 2092 Tunis Tunisia

Correspondence should be addressed to Myriam Abidi bidimyriamgmailcom

Received 6 February 2018 Revised 2 April 2018 Accepted 9 May 2018 Published 24 June 2018

Academic Editor Adina Negrea

Copyright copy 2018MyriamAbidi et alampis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

ampe trophic status assessment of the South Lagoon of Tunis a shallowMediterranean coastal area after its restoration is addressedherein with respect to its various environmental settings which are taken as indicators of water qualityampe lagoon had in the pastwitnessed severe environmental quality issues To resolve these problems a large restoration project of the lagoon was undertakenwhich consisted of dredging the bottom sediments removing areas of water stagnation and improving water circulation After thisrestoration work the lagoon morphology has radically changed In this paper we attempt to evaluate the lagoon waterrsquos trophicstate to analyze the eutrophication risk after almost 16 years In order to achieve these purposes two water quality monitoringcampaigns were conducted (July 2013 and February 2014) Natural and anthropogenic factors controlling the nutrient content ofthe lagoon water have been assessed through both geochemical methods andmultivariate statistical toolsampe results show that thenutrients are from external sources due to the discharge of municipal and industrial wastewater from the surrounding city of thecatchment in the lagoonrsquos south side According to the TRIX index the lagoon remains eutrophic presenting a ldquopoorrdquo waterquality notwithstanding the engineering project due to the high level of nutrients

1 Introduction

Coastal lagoons are very important for the ecologicalpreservation of biodiversity [1] However they are fastturning into threatened ecosystems around the world [2]ampe intense anthropogenic development around this areaalso has negative effects Recently the water quality ofcoastal lagoons in many areas of the world has deteriorateddue to massive discharge of nitrogen and phosphorous fromdomestic and industrial wastewater as well as urban drainage[3ndash5] Consequently there has been a growing interest ineutrophication as one of the most pertinent disturbanceprocesses on aquatic ecosystems caused by humans [6] Dueto increasing human pressure including fisheries tourismdemographic expansion and global climate change thepreservation of biodiversity and natural processes in coastallagoons has become a challenge in recent decades [7]

ampe Tunisian coastline on theMediterranean Sea is about1300 km long Because of the development of its industrialtouristic and agricultural activities Tunisian marine re-sources began to get contaminated ampese activities togetherwith the expansion of its population had affected the qualityof the aquatic environment in the long term

ampe present study is integrated in this framework ampeLagoon of Tunis one of the four major lagoons in Tunisia islocated near the capital and close to the most populated re-gion ampis Mediterranean lagoon is characterized by an an-thropogenic catchment Its geographical location had made itover many decades as a site of domestic and industrial dis-charge causing a massive introduction of nutrients and or-ganic matter ampe combination of hydrodynamic andanthropogenic factors (poor circulation shallow depth (av-erage of 1 meter)) and very high nutrient pollution have ledthe ecosystem to the state of eutrophication It has been

HindawiJournal of ChemistryVolume 2018 Article ID 9859546 17 pageshttpsdoiorg10115520189859546

considered as the most eutrophicated lagoon on the Tunisiancoast [8ndash10]

In order to resolve the pollution problem and to improvethe water quality of the South Lagoon of Tunis (the southbasin of the lagoon of Tunis being the subject of our studies)for ecological and economical purposes an environmentalrestoration project was conducted from April 1998 to July2001 [11 12] ampe overall aim of the project was to achievea good ecological status in the lagoon and to realize sub-stantial land reclamation all around After this restorationwork the lagoon morphology has radically changed

ampe general aspect of the project was to increase theflushing power of the lagoon water with marine water fromthe Gulf of Tunis and to reduce the water residence timeampese purposes were reached by setting two groups of locks inorder to allow water exchange between the Gulf of Tunis andthe lagoon In order to avoid water stagnation different areaslocated in both the Southeast and the southwest side of thelagoon were removed (reducing the lagoon area from 13 km2

to 7 km2) and the shoreline was rectified to be straightenedMoreover polluted sediments were dredged and removedfrom the north area of the lagoon To improve water circu-lation fishery was removed and the Canal of Rades and theCanal of Tunis were restored [13 14]

Understanding the ecosystem response to this restora-tion project is essential to assess its rehabilitation ampe timeelapsed after restoration is a critical indicator of the realrestoration success [15] Indeed this coastal ecosystem re-covery requires a continuous survey through an ecologicaltrophic state evaluation

ampe assessment of the status of the lagoon after 16 years ofthe installation of the restoration works is much needed inorder to project further solutions for the decision makers Inthis study this assessment targetsmainly the nutrient elementsand the trophic index to see if the eutrophication of the lagoonhas been improved or otherwise To our knowledge this is theunique study which is addressing such problematic related tonutrient elements in relation to eutrophication within theLagoon of Tunis as previous investigations were conductedfrom a biological and hydrodynamic point of view only (algaemussels etc) However the trophic status has received littleattention and this research aims to overcome this gap

In this paper these investigations were conductedthroughout the lagoon to assess the restoration level andimprovement of water quality Furthermore we attempt toevaluate the trophic state of lagoon water for eutrophica-tionrsquos risk analysis after almost 16 years

Surface water samples were collected in wet and dryseasons (JulyFebruary) and then were analyzed Distribu-tion maps and plots of chemical parameters were used todetermine the geochemical characteristics of the lagoonwater and to identify major natural and anthropogenicprocesses governing water geochemistry

In addition multivariate statistical analysis such asprincipal component analysis (PCA) and hierarchical clusteranalysis (HCA) were used in order to help interpreting thecomplex data matrices for better understanding of the waterquality and to allow the identification of possible factors thatinfluence the water system [16ndash18]

It is widely recognized that the water quality assessmentin coastal ecosystems is complicated since a great number ofvariables including cause (nutrients) and response (chlo-rophyll a) variables are interrelated [19 20] Several methodsare thus used to characterize water quality and to assesseutrophication In this study the TRIX developed by Vol-lenweider et al [21] is used to estimate the trophic status ofthe lagoon water

2 Materials and Methods

21 Study Area ampe lagoon of Tunis is located in thenortheast of Tunisia Cutting across the lagoon and con-necting the Mediterranean with the old port of Tunis theCanal of Tunis divides the lagoon into two basins commonlyknown as the South Lake and the North Lake of Tunis

ampe South Lagoon of Tunis coordinates extend from 12prime to10deg16primeE longitudes and from 36deg46prime to 36deg48primeN latitudes(Figure 1) ampis area was used to be heavily polluted [8 22]but it has recently been rehabilitated [23] After the resto-ration program the lagoon appears shaped as an eclipsestretching in a SW-NE direction with about 10 km long and35 km wide (Figure 1) It extends over an area of 720 ha witha regular depth of about 21m except in some restricted areason the east side where it reaches amaximumof 5m Its shoresare rectilinear and protected by large rockery stones

ampe lagoon is characterized by a semiarid Mediterraneanclimate ampe annual temperature ranges between 7 and 30degCampe mean annual rainfall is 528mm with interannual var-iations ampe luminosity is about 6 h per day with 155 h inDecember and 359 h in July Evaporation ranges between 62and 201mm respectively in January and July [24]

Coastal lagoons maintain a connection to the seathrough a restricted inlet At the South Lagoon the waterflow between the lagoon and the Gulf of Tunis is impeded bytwo inlets (or outlets) seawater generally flows into thelagoon from the east side through the Canal of Rades (2 kmlength and 4m deep) and goes out from the western sidethrough the Canal of Tunis (10 km length and 45m deep)

ampe hydrodynamic of the lagoon is mainly controlledby wind and tide which is semidiurnal [23 25] ampe locksat Rades and Tunis are opened and closed in an alternativeway imposing a one-way water flow going from the east tothe west ampe average water residence time in the lagoonvaries from 66 to 82 days [25] ampe total exchange ofwater volume with the sea via the Canal of Rades is about257millionmiddotm3day ampe water speed of the lagoon is nothomogenous It varies from 65 cms to no more than5 cms going from the Canal of Rades to the canal ofNavigation leading to the appearance of little stagnationzones in the northwestern part of the lagoon [26](Figure 2)

ampe South Lagoon of Tunis has a drainage watershed of4000 ha where more than 1500 ha are industrial areas (foodindustries wholesale etc) [23] Rapid urbanization aroundthe lagoon during the past decade has resulted in a sub-stantial increase in the volume and pollutant load of thestorm-water and wastewater flowing into the lagoon ampelagoon receives water from draining the urban area of

2 Journal of Chemistry

Megrine runo of newly developed areas after their plan-ning as well as a channel called the belt channel whichprotects the city of Megrine from ooding [27]Whereas theindustrial and domestic water of Jbel Jloud Ben Arous andMegrine located in the west side of the lagoon are dis-charged to the catchment area of the oueds (Oued Essalaasand canal of Ben Arous) and transported to the lagoonDuring the rainy season they are mixed by runo [27] Itreceived about 5500m3day of untreated industrial waste-water enriched with nutrients and heavy metals [23]

211 Sampling and Analysis A spatiotemporal monitoringof nutriments concentrations was carried out in July 2013and in February 2014 Samples were taken from 14 siteswhich cover most of the surface area (Figure 3) In order toestimate the anthropogenic nutrient intake of the lagoonwater samples collected from manholes dumped into thelagoon presented in the map (Figure 3) as point and non-point sources are also taken On the other hand othersamples were taken from the Canal of Rades in order to seethe water quality coming from the Gulf

Tunisia

Algeria Libiya

e Mediterranean Sea

10deg12prime0PrimeE 10deg13prime0PrimeE 10deg14prime0PrimeE 10deg15prime0PrimeE 10deg16prime0PrimeE 10deg17prime0PrimeE 10deg18prime0PrimeE 10deg19prime0PrimeE

36deg4

9prime0Prime

N36

deg48prime

0PrimeN

36deg4

7prime0Prime

N36

deg46prime

0PrimeN

36deg4

5prime0Prime

N

Canal of Tunis

Canal ofRades

Fichingport

Commercialport

Oldharbour

Rades

Megrine

Tunis

MegrineRiadh

Ben Arous

e south lagoon of Tunis

e north lagoon of Tunis

Gulf of Tunis

AgglomerationIndustrial areaQuarry

N

e lagoon shape before the restoration projecte new shape of the lagoon

Forest

Figure 1 Map showing the study area

5000

4000

3000

2000

1000

01000 2000 3000 4000 5000 6000 7000

02 msMegrine

Canalof Rades

Maximum filling speed

Canalof Tunis

(a)

Canalof Tunis

Closing tidal sluices of Rades CanalT = 6 h T = 0 h05 ms

Canalof Rades

1000 2000 3000 4000 5000 6000

0

0

1000

500

1500

2000

2500

(b)

Figure 2Water circulation in the South Lagoon of Tunis (a) lling speed of the lagoon [25] and (b) the direction of water circulation on thelagoon [26]

Journal of Chemistry 3

Temperature pH dissolved oxygen content salinityand transparency were measured in the eld using cali-brated portable digital meters All water samples wereltered through a 45 microm millipore cellulose member andwere stored at 4degC in the laboratory until their subse-quent analysis ose membranes are dried and weighedbefore and after ltration e dierence in weight allowsknowing the total dry mass of suspended particulate matter(SPM) [28]

Dissolved inorganic nutrients (nitrate nitrite ammo-nium and orthophosphate) were measured by standardRodier [29] colorimetric method using UVndashVis spectropho-tometer Nitrate (NO3

minus) wasmeasured colorimetry on 420nmSulfosalicylic acid forms with nitrate in anhydrous environ-ment and releases in basic environment a nitrosalicylatecomplex which is yellow A colorimetric determination of thision allows to determine the concentration of nitrate ions ina solution [29] e nitrite (NO2

minus) was determined by com-plexation with the diazotization of sulfanilamide in and with N(1-naphthyl) ethylene diamine in acidic pH which gavea purple-colored complex Nitrite was measured colorimetryon 540nm [29]e ammonium ions (NH4

+) are treated in analkaline pH with sodium hypochlorite and phenol givingindophenol blue coloration is reaction is catalyzed by

nitroprusside Ammonium was measured colorimetry on640nm [29] Orthophosphates react in the presence of anti-mony molybdate to give phosphomolybdic acid compoundsthat were reduced by ascorbic acid giving a blue colorationOrtho-P was measured colorimetry on 720nm [29]

Turbidity measurements (expressed in NephelometricTurbidity Unit NTU) were performed using a HACH 2100Pturbidimeter

e chlorophyll a (chl a) contents were determined usingthe spectrophotometric method of Lorenzen [30] and fol-lowing the procedure given by Parsons et al [31] after 24 hextractions in 90 acetone at minus5degC in the dark

Spatial distribution maps of these water quality pa-rameters were carried out through GIS 93

22 Statistical Analysis Multivariate statistical analysis ofthe experimental data has been performed using the XlstatTwo multivariate statistical techniques were used the hi-erarchical cluster analysis (HCA) and the principal com-ponent analysis (PCA) In addition Pearsonrsquos correlationanalysis was also performed ese methods are consideredas good tools to classify water samples according to theirgeochemical characteristics [32]

Sampling stationsPoint sourceNon-point source

N

Gulf of Tunis

km21050

Canalof Rades

Megrine

Canal of TunisTunis

C14

C13

C8 C7

C6

C5

C2C3C4

C1C9

C10C12

C11

36deg49prime0PrimeN

36deg48prime30PrimeN

36deg48prime0PrimeN




36deg46prime0PrimeN

36deg45prime30PrimeN 36deg45prime30PrimeN

36deg46prime0PrimeN


36deg47prime0PrimeN


36deg48prime0PrimeN


36deg49prime0PrimeN10

deg11prime3

0PrimeE

10deg1

2prime3

0PrimeE

10deg1

3prime3

0PrimeE

10deg1

4prime3

0PrimeE

10deg1

5prime3

0PrimeE

10deg1

6prime3

0PrimeE

10deg1

7prime3

0PrimeE

10deg1

8prime3

0PrimeE

10deg1

8prime3

0PrimeE

10deg1

8prime0Prime

E10

deg18prime

0PrimeE

10deg1

7prime0Prime

E10

deg17prime

0PrimeE

10deg1

7prime3

0PrimeE

10deg1

2prime3

0PrimeE

10deg1

1prime3

0PrimeE

10deg1

3prime3

0PrimeE

10deg1

6prime0Prime

E

10deg1

6prime3

0PrimeE

10deg1

6prime0Prime

E

10deg1

5prime0Prime

E

10deg1

5prime3

0PrimeE

10deg1

5prime0Prime

E

10deg1

2prime3

0PrimeE

10deg1

2prime0Prime

E

10deg1

3prime0Prime

E10

deg13prime

0PrimeE

10deg1

4prime0Prime

E10

deg14prime

0PrimeE

10deg1

4prime3

0PrimeE

Figure 3 Map showing the location of sampling stations


23 Trophic State Assessment

231 Trophic Index (TRIX) ampe TRIX proposed by Vol-lenweider et al [21] which can be considered as an adap-tation of Carlsonrsquos TSI to transitional waters is used in orderto assess the trophic state of the lagoon ampe TRIX is fre-quently used to characterize the ecosystem trophic statusampe TRIX has been applied to many ecosystems of coastalmarine waters such as the Tyrrhenian [33] and the CaspianSeas [34] Bizerte Lagoon in Tunisia [35] and the Greekcoastal lagoon [36] are among others

It is a mathematical tool derived from the combinationof dissolved inorganic nitrogen inorganic phosphorusdissolved oxygen and chlorophyll a ampe TRIX analyticalexpression is given as follows

TRIX log10(DINlowastDIPlowast |DDO|lowast chl(a)) + a1113858 1113859

b (1)

where chl(a) represents the chlorophyll a concentration(in microgL) while |DDO| represents the absolute valuepercentage deviation of the oxygen concentration fromsaturation conditions (in ) DIN and DIP representdissolved inorganic nitrogen (in microgL) and dissolvedinorganic phosphorus (in microgL) respectively ampe pa-rameters a 15 and b 12 are scale coefficients usedto fix the index lower limit and the scale ranges from 0 to10 [33]

According to Vollenweider et al [21] the scores are asfollows

(i) TRIXlt 4 indicates high state of water quality withlow eutrophication

(ii) 4ltTRIXlt 5 indicates good state of water qualitywith medium eutrophication

(iii) 5ltTRIXlt 6 indicates bad state of water qualitywith high eutrophication

(iv) 6ltTRIX indicates poor state of water quality withhigh eutrophication levels

3 Results and Discussion

Descriptive statistics for the minimum maximum andaverage concentrations for each variable at each samplingperiod are reported in Table 1

31 Physicochemical Parameters ampe collected water fromthe Southern lagoon of Tunis were characterized by a tem-perature ranging between 288 and 30degC and between 151and 175degC respectively in July 2013 and February 2014with salinity values that range between 483 to 491permil and475 to 485permil respectively in summer and in hibernalseasons (Table 1) ampese parameters undergo wide seasonalvariations

pH values vary from 848 to 895 in July and from 85 to894 in February

ampese parameters show a progressive increase in thewater flow direction going from the east to the west(Figure 4) ampis variation is supported by evaporation and

by the hydrodynamic regime of the lagoon driven byseawater circulation from the inlet gates to the outlet onesfrom the east to the west

Dissolved oxygen values in the lagoon varied between29 and 44mgL (514 and 756 of saturation) in July andbetween 65 and 11mgL (865 and 1483 saturation) inFebruary Dissolved oxygen in aquatic ecosystems is thefunction of many physicochemical parameters whichgovern their solubility Obviously oxygen solubility in-creases as salinity and temperature decrease which could bethe reason of the low DO concentration in summer

ampe important biological processes associated with ox-ygen distribution are photosynthesis respiration and de-composition [37] In the South Lagoon of Tunis the lowestvalues of DO are measured in July mainly due to the highrate of bacterial degradation of organic matter and thehighest values of the algae population presented during thisseason In contrast the lagoon water is well oxygenated andeven oversaturated in February due to wind agitation es-pecially in low depth as well as the decrease of biomassproduction

ampe compilation of the distribution maps of dissolvedoxygen contents (Figure 5) with the algal distribution of thelagoon (Figure 6) shows that the most oxygenated water is inthe west side of the lagoon where the water depth is low andrich in algae

SPM ranges from 0025 to 0043mgL and from 0018 to0032mgL respectively in July 2013 and February 2014ampehighest values could be attributed to the low depth of thewater where the particle resuspension is much easier and tothe decompositionrelease of organic particles from themacrophytes in summer ampe turbidity varies between 8 and20 (100NTU) in July due to the high rate of chlorophyll a Inthe other hand the lagoon is almost transparent and theturbidity ranges between 1 and 9 (100NTU) in FebruaryampeSecchi disk transparency values vary between 13 and 2m inJuly and between 15 and 18m in February which indicatinga generally moderate water visibility ampe lowest values oftransparency were recorded in July due to the growth ofchlorophyll a

32 Nutrients For the lagoon water samples the nitrogeninorganic compounds are mainly composed by nitrates (90)

Nitrite contents range between 008 and 009mgL inJuly and between 053 and 076mgL in February Am-monium varies between 0071 and 0117mgL in July andfrom 0042 to 0052mgLin February Nitrate contents varybetween 806 and 13mgL in July and from 208 to1558mgL in February (Table 1) ampese values are close tothose found by Saccon et al in the Marano lagoon (Italy)[39] As shown in Table 1 the lagoon water is richer innutrient compared to seawater

Rapid mobilization resulted in low values of ammoniumand nitrite In fact these elements are transitory and unstablein water having very weak dissolved oxygen concentrations[40] Ammonium may differ from steady-state conditionsreflecting the balance between production through miner-alization of organic matter [41] nitrificationdenitrification


Tabl

e1

Statistical

summaryof

physicochemical

parametersandnu

trientsin

SouthLagoon

ofTu

nis

Depth

(m)

T (deg C)

pHDO

(mgL)

Salin

ity(permil

)Con

ductivity

(Scm)

SPM

(mgL)

NH

4+

(mgL)

NO2minus

(mgL)

NO3minus

(mgL)

Ortho

-P(m

gL)

Chl-a

(microgL)

Pheo

(microgL)

Turbidity

(100

NTU

)Transparency

(m)

July

campaign

Minim

um2

288

848

3483

568

0025

0071

0079

9295

2129

1108

4424

813

Maxim

um54

30895

44

491

577

0043

0117

0095

14429

2409

3324

8759

242

Average

29

295

872

35

486

571

0034

0088

0087

11593

2275

2137

6230

157

15

February

campaign

Minim

um18

151

85

62

475

559

0019

0043

0550

3070

1601

0997

0598

115

Maxim

um42

175

894

11484

569

0032

0052

0901

15580

2958

2659

2726

918

Average

27

159

873

8481

566

0027

0046

0643

9423

1790

1994

1612

416

Gulfo

fTun

is(July)

mdash227

757

69

435

511

0244

011

1375

0465

Non

points

ource

mdash247

755

39

61

712

0291

0399

11063

1283

Pointsources

mdash247

763

39

518

518

0018

0063

11265

1243


and consumption by the abundant primary producers livingnear the sediment-water interface [42]

As for nitrate the characterization of its origins in the lagoonis much more diordfcult to achieve because of complex mixing

processes among dierent water types like seawater rainwaterandwastewater charges from the catchment area [39] Generallynitrate can be originated from airborne (atmospheric) nitri-cation process or agricultural (leaching of agricultural land)

July 2013

29ndash295285ndash29

295ndash30

Gulf of Tunis

N

Gulf of Tunis

N

February 2014

15ndash155


Tem

pera

ture

(degC)

Gulf of Tunis

Salin

ity (permil

)

N

July 201349ndash495485ndash4948ndash485

Gulf of Tunis

N

February 201448ndash485475ndash4847ndash475

Gulf of Tunis

N

July 2013

86ndash8884ndash86

88ndash896

pH

Gulf of Tunis

N

February 2014

86ndash8884ndash86

88ndash89

Figure 4 Physicochemical distribution maps of the South Lagoon of Tunis


In our case the lagoon catchment area is exclusivelyoccupied by urban or industrial zones which mean that thehigh rate of nitrate intake in the lagoon is not derived fromagricultural activities erefore the nitrate is formed in thelagoon by nitrication of NH4

+ that may enter the lagoondirectly from urban or industrial N-breang wastewater asanthropogenic sources or could be produced in situ byremineralization of organic matter

Spatial variation maps of nitrate contents show that thedistributions are inuenced by liquid discharges on thesouth side of the lagoon showing a positive gradient fromsouth to north e highest levels are those sampled near thedischarge site As they move away the contents decrease andbecome homogenous in the rest of the study area whichmeans the western and eastern parts of the lagoon (Figure 7)

Furthermore it is important to stress that NH4+ and NO2

minus

nitrication can start even towards the lagoon and willconsequently increase the NO3

minus concentration intake in thesampled water [39 43]

e orthophosphate contents vary from 160mgL to24mgL in July and from 16mgL to 294mgL in February(Table 1) Orthophosphate content variations are caused byprimary production uptake and can be aected by variousprocesses like adsorption and phosphate desorption andbuering action of sediments under environmental condi-tion change (temperature and dissolved oxygen) [44 45]

e cross-plot orthophosphate-total dissolved inorganicnitrogen (DIN) did not show any correlation (r2 013 forJuly campaign and r2 040 for February campaign) forsampled water (Figure 8) In shallow coastal ecosystems such

N

7ndash86ndash7

8ndash9

February 201410ndash119ndash10

Diss

olve

d ox

ygen

(mg

L)N

3ndash35

July 20134ndash4535ndash4

Gulf of Tunis Gulf of Tunis

Figure 5 Dissolved oxygen distribution map of the South Lagoon of Tunis

N

km0 1

Caulerpa prolifera coverage0

0ndash20

20ndash50

50ndash80

80ndash100

Figure 6 e distribution of Caulerpa prolifera in the South Lagoon of Tunis in summer 2014 [38]


Gulf of Tunis

N

7ndash99ndash11

July 2013

11ndash1313ndash15

Gulf of Tunis

N

2ndash55ndash8

February 2014

8ndash1212ndash15

Gulf of Tunis

N


July 2013


Gulf of Tunis

N


February 2014


Gulf of Tunis

N

007-008008-009

July 2013

009-0101ndash011

Gulf of Tunis

N


February 2014


Gulf of Tunis

Nitr

ate (

mg

L)N

itrite

(mg

L)A

mm

oniu

m (m

gL)

Ort

ho-P

(mg

L)

N

July 2013

22-2321-22

23-24

Gulf of Tunis

N

February 2014

15ndash21ndash15

2ndash25

Figure 7 Nutrient distribution maps of the South Lagoon of Tunis


as the South Lagoon of Tunis remineralization of the or-ganic matter in the sediment andor in suspended particlescould often be a major source of dissolved inorganic nu-trients in the water column [46ndash48] Although this study wasnot designed to investigate the role of sediments as an in-ternal source of nutrients to the water column their in-uence in the nutrientrsquos regeneration was apparent Insummer mineralizing of organic matter at the sedimentinterface is accelerated leading to a supplementary nutrientrelease to the water column [49ndash52]

Just like nitrate the spatial distributions of ammoniumand ortho-P contents show that the highest levels arerecorded in the south side of the lagoon Nitrite contents arehomogeneous in July whereas a positive gradient is noticedgoing from the south part to the north part in Februaryisdistribution can be attributed mostly to urban wastewaterand runo (Figure 7)

321 Ratio NIDOrtho-P e NP ratio is often used in theprediction of the limiting nutrient for phytoplankton pro-duction Despite the advances nutrients limitation in coastalwater is still an open question ere is an ongoing debateregarding the choice of the form of phosphorus and nitrogenused for calculating Redeld ratio [53] using the total formor just the inorganic form

For the present study in NP ratio computation thedissolved inorganic nitrogen (DIN) and orthophosphorus(ortho-P) are used [54ndash56] In algal cells the approximateratio of nitrogen to phosphorus mass (Redeld ratio) is 72 1(grams) or 16 1 (atoms)

Figure 9 shows the calculated molar ratios ofDINortho-P for all data It varies between 3 and 49 for theJuly campaign and between 17 and 73 for the Februarycampaign e low N P molar ratios (less than 16 1)suggest N-limitation in the sampled water Nonetheless theN-limitation of coastal ecosystems (lagoon) might not

necessarily be applied especially when they are under highanthropic pressure [57]

33 Chlorophyll a e chlorophyll a contents range from111 to 332 microgL in July and from 099 to 266 microgL inFebruary Pheopigmant contents vary from 442 to 876 microgLand from 06 to 272 microgL respectively in July and FebruaryPheopigmant contents are higher than the chlorophyll a inJuly which coincide with the end of the growth cycle ofmacroalgae and seagrass and their decomposition

e spatial distribution of pheopigmants in the sameperiod is almost the opposite distribution of the chlorophylla e highest concentrations of chl a are in the west and thesoutheastern part of the lagoon where the depth varies from18 to 24m However the lowest concentrations are in theEast side of the lagoon where the water depth varies from 38to 51m (Figure 10) Positive gradient is established with theincoming water from the east side of the lagoon to the westside

C1

C2

C3 C4C5

C6

C7

C8

C9

C10

C11

C12

C13

C14

2

21

22

23

24

25

9 10 11 12 13 14 15

Ort

ho-P

(mg

L)

DIN (mgL)

r2 = 013

July samples

(a)

C1C2 C3C4

C5

C6C7

C8 C9

C10

C11

C12

C13

C14

15

2

25

3

Ort

ho-P

(mg

L)

r2 = 040

2 4 6 8 10 12 14 16 18DIN (mgL)

February samples

(b)

Figure 8 Plot of ortho-P by NID

02468

1012141618

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Ratio

DIN

ort

ho-P

Samples stations

February ratioJuly ratio

Redfield ratio

Figure 9 Ratio NP for the South Lagoon of Tunis water samples


34 Statistic Study In order to classify the trends of thiscoastal lagoon a detection of signicant relationships be-tween indices (dierences of environmental parameters andnutrients) and samples was tested

341 Correlation Matrix Pearsonrsquos correlation coeordf-cient matrix of the physicochemical parameters nutrientschlorophyll a and pheopigmant contents was calculated(Table 2) e following results are drawn

(i) Signicant negative correlation between ammo-nium and dissolved oxygen contents (r2 minus087)which conclude that ammonium is controlled byammonication

(ii) Negative correlation between nitrite and ammo-nium (r2 minus087) and positive correlation betweendissolved oxygen and nitrite (r2 079) whichindicates a continuous process of nitrosation

(iii) Nitrate does not show any correlation with nitriteammonium and dissolved oxygen that can be

explained by an external input of nitrate in the lagoonwater from urbanindustrial water discharge

(iv) Ortho-P concentrations were positively correlatedwith temperature (r2 064) indicating phosphaterelease from sediments of the lagoon

(v) Signicant positive correlation between pheo-pigmants and temperature (r2 091) and negativecorrelation with dissolved oxygen (r2 minus088) showa high rate of pheopigmants in July matching theend of algal growth cycle ose parameters cor-respond to the eutrophic condition in the dryseason

(vi) Turbidity presents a positive correlation withtemperature (r2 085) SPM (r2 085) andpheopigmants (r2 078) ese parameters cor-respond to the eutrophic condition in the dryseason On the contrary turbidity and transparencyhave an antagonist behavior (r2 minus045) and highvalue of turbidity causes low visibility of lagoonwater

15ndash2505ndash15

Gulf of Tunis

Chlo

roph

yll a

(microg

L)

15ndash209ndash15

Gulf of Tunis

N


N


1ndash1505ndash1

Gulf of Tunis

N

55ndash6545ndash55

Gulf of Tunis

Pheo

pigm

ants

(microg

L)



N

Figure 10 Spatial distribution maps of chlorophyll a (microgL) and pheopigmants (microgL) in surface water of the South Lagoon of Tunis


342 Principal Components Analysis PCA To evaluate thetemporal and spatial variations of the studied parameters(physicochemical parameters and nutrients) in the Southernlagoon of Tunis a principal component analysis (PCA) wasapplied

ampe used variables are temperature pH dissolved oxygencontent salinity suspended particulate matter (SPM) tur-bidity transparency NH4

+ NO2minus NO3

minus ortho-P chloro-phyll a (chl a) and pheopigmants (pheog)

ampree components were extracted which explained7557 of the total varianceampe first factor (PC1) accountingfor 5465 of the total variance is strongly correlated pri-marily with dissolved oxygen (091) and nitrite (095) on thepositive side and negatively correlated with water temperature(minus099) and with ammonium (minus089) and pheopigmants(minus093) showing the inverse relationship between tempera-ture and dissolved oxygen and between nitrite and ammo-nium (Table 3) It is also defined by less important salinity andSPM HPO4 is also correlated with PC1 (Table 3) ampereforePC1 mainly represents the seawater marine influence fromthe gulf of Tunis which has an important effect on the lagoonwith continuous flushing buffering and dilution effect

PC2 explained that 1397 of the total variance wasprincipally represented by pH and nitrate (Table 3) Addi-tional 952 of the total variance was explained in PC3 andwas represented by transparency

ampe correlation circles of both components (PC1 andPC2) (Figure 11) show that chlorophyll a and nitrate havethe same behavior explaining that the nutrient intakestimulates algae growth ampen pheopigmants-temperature-ammonium-SPM and turbidity have the same behaviorindicating the eutrophic state in the July campaign

ampe loading plot of the two factors (PC1PC2) (Figure 11)shows the presence of two different groups

(i) Group I included the July samples ampey are dom-inated by ammonium turbidity SPM pheopigm-ants temperature and salinity

(ii) Group II included the February samples at whichthe dominance of dissolved oxygen is determined

PCA analysis shows a clear seasonal variation IndeedFebruary samples are well oxygenated and the July samplespresent eutrophicated characters

343 Cluster Analysis Hierarchical clustering based on theEuclidean distances as similarity coefficient allows the re-lationship investigation between the observations of thevariables of a dataset in order to recognize the existence ofgroups It is applied to detect spatial similarity for samplingsite grouping In our study 3 clusters that present similarcharacteristic features are identified (Figure 12)

(i) Cluster I is represented by samples taken from thewest side of the lagoon in the July campaign (S4 S8S9 S11 S12 and S14)

(ii) Cluster II concerns the July samples taken in the eastside of the lagoon (S1 S2 S3 S5 S6 S7 S10 and S13)

(iii) Cluster III characterizes the samples collected in theFebruary campaign that can be subsided in twosubclusters

(i) Samples located in the eastern part of the lagoon(S1 S2 S3 S6 and S7)

(ii) Samples collected in the western part of the la-goon (S4 S5 S8 S9 S10 S11 S12 S13 and S14)

ampis classification allow us to divide the lagoon in twoparts according to the physicochemical parameters theeastern part under the influence of seawater coming from thegulf characterized by the lowest levels of temperature pH

Table 2 Pearson correlation matrix of water quality variables of the South Lagoon of Tunis

Variables TdegC pH O2 Salinity SPM NH4+ NO2

minus NO3minus Ortho-P Chl a Pheo Turbidity Transparency

TdegC 1 minus004 minus093 074 068 090 minus097 031 064 012 091 085 minus039pH 1 032 032 002 minus018 minus002 041 027 020 minus009 012 minus009O2 1 minus057 minus065 minus087 089 minus015 minus054 minus006 minus088 minus078 035Salinity 1 050 064 minus072 041 066 010 072 058 minus042SPM 1 049 minus060 004 023 011 063 085 minus051NH4

+ 1 minus087 031 057 007 087 070 minus037NO2minus 1 minus038 minus065 minus014 minus087 minus079 034

NO3minus 1 048 012 031 023 007

Ortho-P 1 007 061 046 minus007Chl a 1 020 015 012Pheo 1 078 minus031Turbidity 1 minus045Transparency 1

Table 3 Results of principal component analysis are shown ascorrelation values between the variables and the principal com-ponents for the first three principal components (PC1ndashPC3)

PC1 PC2 PC3TdegC minus099 minus007 008pH minus004 081 minus051O2 091 031 minus021Salinity minus079 030 minus016SPM minus072 minus026 minus043NH4

+ minus089 minus013 023NO2minus 095 minus002 minus012

NO3minus minus037 071 018

Ortho-P minus068 044 025Chl a minus014 031 minus005Pheo minus093 minus006 016Turbidity minus088 minus008 minus024Transparency 045 027 068


salinity and dissolved oxygen contents and the western partwith the highest levels of these parameters

Water coming from the Canal of Rades exerts a con-tinuous ashing on the lagoon However this dilution eectis limited in the east side of the lagoon To road the outletgate (on the west) the lagoon water are enriched

35 Trophic State Assessment In these last years theconcern of managers and scientists has grown and

dierent classications of the trophic state of coastal waterbased on nutrients and oxygen thresholds have beensettled [58ndash60]

emorphology of the South Lagoon of Tunis has totallychanged during the last decades (before and after the res-toration project) For this propose a comparative analysisevaluating the restoration project impact on physico-chemical parameters and the nutrient contents of the lagoonseems to be extremely interesting to check the good func-tioning of the restored ecosystem In order to track the

T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1

ndash1 ndash05 0 05 1

PC2

(13

97

)

PC1 (5465)

Variables (axes PC1 and PC2 6863)

NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5

ndash5 ndash4 ndash3 ndash2 ndash1 0 1 2 3 4 5

PC2

(13

97

)

PC1 (5465)

Biplot (axes PC1 and PC2 6863)

Group I

Group II

Increasing gradient ofeutrophic conditions

J-July samplesF-February samples

F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)

Figure 11 Circle of correlation on (PC1 and PC2) and (PC1 and PC3) and spatial distribution of variables and individuals in the axes systemPC1 and PC2


evolution of the trophic conditions in the South Lagoon ofTunis the TRIX [21] was selected

Figure 13 shows the water trophic status in the SouthLagoon of Tunis before during and after the restorationwork Before restoration Ben Souissi [22] showed thatnitratesphosphorus and chl a rates reached high levels in theSouth Lagoon of Tunis e lagoon water quality was cat-egorized as ldquopoorrdquo according to TRIX index calculated fromthe mean monthly values e best trophic state was reg-istered during the restoration work the lagoon was cate-gorized as ldquohighrdquo In the present work the TRIX valuesranged from 89 to 99 Despite the hydrodynamic systemimprovement in the lagoon the lagoon water quality wascategorized as ldquopoorrdquo

e trophic status of marine coastal ecosystem as-sessment is based on measurements of combinations ofbiotic and abiotic variables [21] as well as the main

elements (eg inorganic and organic N and P) andmolecules (organic matter chlorophyll a concentrations)that had been used as indicators of biomass in the watercolumn [61] However the increase in the primary pro-duction levels is not the only factor controlling the trophicstatus of a marine ecosystem ere is also transparencysunshine and water circulation which are considered asimportant factors too [62] For example increased levels ofprimary production can also be associated with the ac-cumulation of large amounts of detrital organic materials[63]

During the restoration of the South Lagoon of Tunis anew hydraulic design was required e hydrological pa-rameters show an improvement of the physicochemical pa-rameters due to the newly produced hydrodynamicpermanent seawater exchanges the water residence timereduction the lagoon water volume increase and a con-tinuous ushing

e engineering work improved the quality but did notfully reach the expected results e South Lagoon of Tunisstill records a poor water quality classication As shallowmarine ecosystems the arid climate (characterized by a highevaporation rate and temperature) and the continuous in-take of nutrients can modify the structure and the biology ofthe water column at very short time intervals (from minutesto hours) Despite dredging the bottom sediment of thelagoon the South Lagoon of Tunis is still contaminated byorganic matter and records a high rate of nutrients even aftermanagement work ese elements may under preciseconditions [64ndash66] be released and might be diused fromthe water-sediment interface

Moreover in the anoxic phase that could happen in thelagoon due to the high summer temperature the exchange

F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500

Increasinggradient of

physico-chemicalparameters

Figure 12 Dendrogram for the South Lagoon of Tunis samples

2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations

TRIX (February 2014) End of restoration programTRIX (July 2013) Before restoration

Poor

ModerateGoodHigh

Figure 13 Variation of TRIX index [21] for the South Lagoon ofTunis


with the sea seems to be ineffective for flushing to decreasenutrient contents

4 Conclusion

ampe purpose of this manuscript was to give an assessment ofthe lagoon status using geochemical and statistical ap-proaches ampe results indicate that the spatial distribution oftemperature salinity and pH is under the control of watercirculation in the Southern lagoon of Tunis ampey showa slight increase from the east to the west

ampe lagoon water shows a high level of nutrients (NO3minus

NO2minus NH4

+ and ortho-P) compared to the incoming waterfrom the sea ampis is essentially due to natural (nitrificationrelease from the sediments and primary production) andanthropogenic (wastewater and runoff) sources

Based on nutrient contents DO and chlorophyll a TRIXproposed by Vollenweider et al [21] was calculated Itdemonstrated that the lagoon has reached the eutrophicstatus with a poor water quality index ampe trophic status ofthe South Lagoon of Tunis is worrying and requires a seriousintervention

PCA identified two groups (winter sampling campaignsummer sampling campaign) the eutrophic status of the la-goon water is highlighted in July campaign ampe CHA analysisallowed us to divide the lagoon into two parts (east and thewest parts) where the west side is richer in nutrients and inphysical-chemical parameters compared to the east side

ampe current status of the lagoon requires serious interestgiven its vulnerability and fragile balance in order to avoidthe failure of the engineering works (if a status-quo ismaintained)

Data Availability

ampe data used to support the findings of this study areavailable from the corresponding author upon request

Disclosure

ampis work was partially presented in international confer-ence days ICEWE 2017

Conflicts of Interest

ampe authors wish to confirm that there are no knownconflicts of interest associated with this publication andthere has been no significant financial support for this workthat could have influenced its outcome

Acknowledgments

ampe authors would like to thank Pr Amina MabroukFaculty of Sciences of Tunis University Tunis El Manar forher helpful assistance to improve the manuscript

References

[1] S Cataudella D Crosetti and F Massa Studies and ReviewNo 95 General Fisheries Commission for the Mediterranean

Coastal Lagoons Sustainable Management and Interactionsamong Aquaculture Capture Fisheries and the EnvironmentFood and Agriculture Organization of the United NationsRome Italy 2015

[2] J J Berzas L F Garcia R C Rodrıguez and M AlvarezldquoEvolution of the water quality of a managed natural wetlandTablas De Dimiel National Park (Spain)rdquo Water Researchvol 34 no 12 pp 3161ndash3170 2002

[3] G Cabeccediladas M Nogueira and M J Brogueira ldquoNutrientdynamics and productivity in three European estuariesrdquoMarine Pollution Bulletin vol 38 no 12 pp 1092ndash1096 1999

[4] J E Cloern ldquoOur evolving conceptual model of the coastaleutrophication problemrdquo Marine Ecology Progress Seriesvol 210 pp 235ndash265 2001

[5] C B Lopes A I Lilleboslash J M Dias E Pereira C Vale andA C Duarte ldquoNutrient dynamics and seasonal succession ofphytoplankton assemblages in a Southern European EstuaryRia de Aveiro Portugalrdquo Estuarine Coastal and Shelf Sciencevol 71 no 3-4 pp 480ndash490 2007

[6] European Commission ldquoDirective 91271EEC concerningurban waste water treatmentrdquoOfficial Journal of the EuropeanCommunities pp 40ndash52 1991

[7] J E Graham R L Peter S B Neville G-H KarenD Michael andM Peter ldquoConservation of natural wildernessvalues in the Port Davey marine and estuarine protected areasouth-western Tasmaniardquo Aquatic Conservation Marine andFreshwater Ecosystems vol 20 no 3 pp 297ndash311 2010

[8] J Zaouali ldquoLac de Tunis 3000 years of engineering andpollution a bibliographical study with commentsrdquo UNESCOReports in Marine Science vol 26 pp 30ndash47 1983

[9] OCDE Eutrophisation des Eaux Methodes de SurveillenceDrsquoevaluation et de Lutte Organisation for Economic Co-operation and Development Paris France 1982

[10] Z Armi E Trabelsi S Turki B Bejaoui and N Ben MaızldquoSeasonal phytoplankton responses to environmental factorsin a shallowMediterranean lagoonrdquo Journal of Marine Scienceand Technology vol 15 no 4 pp 417ndash426 2010

[11] J Vandenbroeck and R Ben Charrada ldquoRestoration anddevelopment project of South Lake of Tunis and its shoresrdquoTerra et Aqua vol 85 pp 11ndash20 2001

[12] S Souissi O Daly Yahia-Kefi and M N Daly Yahia ldquoSpatialcharacterization of nutrient dynamics in the Bay of Tunis(south-Western Mediterranean) using multivariate analysesconsequences for phyto-and zooplankton distributionrdquoJournal of Plankton Research vol 22 no 11 pp 2039ndash20592000

[13] SPLT STUDISOGREAH Societe drsquoetude et de Promotion deTunis Sud (Etude de la maree Travaux de Restauration du lacsud de Tunis et de ses Berges) 1998

[14] SERAH Etude drsquoamenagement du lac sudmdashRapport Analysedes eaux du lac sud Etude realisee pour le compte de la SocietedrsquoEtude et de Promotion de Tunis Sud 1992

[15] M Abidi R Ben Amor and M Gueddari ldquoGeochemistry ofnutrients in the South lagoon of Tunis Northeast of Tunisiausing multivariable methodsrdquo in Proceedings of the 19th In-ternational Conference on Energy Water and EnvironmentalWorld Academy of Science Engineering and TechnologyInternational Scientific Committees and Editorial ReviewBoards Istanbul Turkey July 2017

[16] Y Ouyanga P Nkedi-Kizza Q T Wuc D C H Shinde andC H Huang ldquoAssessment of seasonal variations in surface waterqualityrdquo Water Research vol 40 no 20 pp 3800ndash3810 2006

[17] S Shrestha and F Kazama ldquoAssessment of surface waterquality using multivariate statistical techniques a case study


of the Fuji river basin Japanrdquo Environmental Modelling ampSoftware vol 22 no 4 pp 464ndash475 2007

[18] E L Bahri Trabelsi Z Armi N Trabelsi-Annabi A Shili andN Ben Maiz ldquoWater quality variables as indicators in therestoration impact assessment of the north lagoon of TunisSouth Mediterraneanrdquo Journal of Sea Research vol 79pp 12ndash19 2013

[19] L Ignatiadis M Karydis and P Vounatsou ldquoA possiblemethod for evaluating oligotrophy and eutrophication basedon nutrient concentration scalesrdquo Marine Pollution Bulletinvol 24 no 5 pp 238ndash243 1992

[20] R A Vollenweider R Marchetti and R Viviani ldquoMarinecoastal eutrophicationrdquo in Proceedings of an InternationalConference Bologna Italy p 1310 March 1990

[21] R A Vollenweider F Giovanardi G Montanari andA Rinaldi ldquoCharacterization of the trophic conditions ofmarine coastal waters with special reference to the NWAdriatic Sea proposal for a trophic scale turbidity anda generalized water quality indexrdquo Environmetrics vol 9no 3 pp 329ndash357 1998

[22] J Ben Souissi Impact de la Pollution sur les CommunautesMacro benthiques du Lac Sud de Tunis avant sa RestaurationEnvironnementale PhD thesis Faculte des sciences de TunisTunis Tunisia 2002

[23] Z Jouini R Ben Charrada and M Moussa ldquoCaracteristiquesdu Lac Sud de Tunis apres sa restaurationrdquo Marine vol 15no 1-2 pp 3ndash11 2005

[24] National Institute of Meteorology INM Climate Data Reportfor the Period 2007ndash2011 2012

[25] Z Jouini Le Fonctionnement Hydrodynamique et Ecologiquedu lac sud de Tunis apres les Amenagements DEA ENITSpringfield VA USA 2003

[26] M Kochlef Contribution a Lrsquoetude du FonctionnementHydrodynamique du lac Sud Tunis apres les TravauxDrsquoamenagement DEA National Agronomy Institute ofTunisia Carthage University Tunis Tunisia 2003

[27] Departement Hydraulique Urbaine (DHU) Etude de Pro-tection du Grand Tunis contre les inondationsmdashPhase 1mdash1erePartie Juin 2006 Ministere drsquoEquipement DepartementHydraulique Urbaine (DHU) Rabat Morocco 2015

[28] A Aminot and R Kerouel ldquoDosage automatique des nutri-ments dans les eaux marines methodes en flux continurdquo inMethodes Drsquoanalyse en Milieu Marin p 188 Ifremer Issy-les-Moulineaux France 2007

[29] J Rodier LrsquoAnalyse de lrsquoeau Eaux Naturelles Aux ResiduairesEau de Mer Chimie Physico-Chimie Bacteriologie BiologieDunod Paris France 2006

[30] C J Lorenzen ldquoDetermination of chlorophyll and pheo-pigments by spectrophotometric equationsrdquo Limnology andOceanography vol 12 no 2 pp 343ndash346 1967

[31] T R Parsons ldquoA manual of chemical and biological methodsfor seawater analysis Pergamon Oxford sized algae andnatural seston size fractionsrdquo Marine Ecology Progress Seriesvol 199 pp 43ndash53 1984

[32] B Tlili-Zrelli F Hamzaoui-Azaza M Gueddari andR Bouhlila ldquoGeochemistry and quality assessment ofgroundwater using graphical and multivariate statisticalmethods A case study Grombalia phreatic aquifer (North-eastern Tunisia)rdquo Arabian Journal of Geosciences vol 6 no 9pp 3545ndash3561 2013

[33] F Giovanardi and R A Vollenweider ldquoTrophic conditions ofmarine coastal waters experience in applying the TrophicIndex TRIX to two areas of the Adriatic and Tyrrhenian seasrdquoJournal of Limnology vol 63 no 2 pp 199ndash218 2004

[34] M Shahrban and A Etemad-Shahidi ldquoClassification of theCaspian Sea coastal waters based on trophic index and nu-merical analysisrdquo Environmental Monitoring and Assessmentvol 164 no 1ndash4 pp 349ndash356 2010

[35] B Bejaoui Z Armi E Ottaviani et al ldquoRandom forest modeland TRIX used in combination to assess and diagnose thetrophic status of Bizerte lagoon southern MediterraneanrdquoEcological Indicators vol 71 pp 293ndash301 2016

[36] C Chrysoula G Giordani and E Papastergiadou ldquoAssess-ment of ecological quality of coastal lagoons with a combi-nation of phytobenthic and water quality indicesrdquo MarinePollution Bulletin vol 86 pp 411ndash423 2014

[37] S R Aston ldquoNutrients dissolved gases and general bio-geochemistry in estuariesrdquo in Chemistry and Biogeochemistryof Estuaries E Olausson and I Cato Eds pp 233ndash262 JohnWiley and Sons New York NY USA 1980

[38] A Yahyaoui Distribution Biomass and Meadow Structure ofCaulerpa prolifera in the Southern Lagoon of Tunis NationalAgronomy Institute of Tunisia Carthage University TunisTunisia 2014

[39] P Saccon A Leis A Marca et al ldquoDetermination of nitratepollution sources in the Marano lagoon (Italy) by usinga combined approach of and isotopic techniquesrdquo ProcediaEarth and Planetary Science vol 7 pp 758ndash761 2013

[40] G Copin-Montegut Chemistry of Seawater OceanographicOceanographic Institute Kerala India 1996

[41] G Bally V Mesnage J Deloffre O Clarisse R Lafite andJ P Dupont ldquoChemical characterization of porewaters in anintertidal mudflat of the Seine estuary relationship to erosion-deposition cyclesrdquo Marine Pollution Bulletin vol 49 no 3pp 163ndash173 2004

[42] M Vidal and J A Morguı ldquoShort-term pore water ammo-nium variability coupled to benthic boundary layer dynamicsin Alfacs bay Spain (Ebro Delta NW Mediterranean)rdquoMarine Ecology Progress Series vol 118 pp 229ndash236 1995

[43] P Saccon A Leis A Marca et al ldquoMulti-isotope approachfor the identification and characterisation of nitrate pollu-tion sources in the Marano lagoon (Italy) and parts of itscatchment areardquo Applied Geochemistry vol 34 pp 75ndash892013

[44] C R Pomeroy E E Smith and CM Grant ldquoampe exchange ofphosphate between estuarine water and sedimentsrdquo Lim-nology and Oceanography vol 10 no 2 pp 167ndash172 1965

[45] H Jamila B Mouldi and G Moncef ldquoAssessment of thewater quality of Bizerte lagoon of Tunisia by use of statisticalanalysesrdquo Journal of Waste Water Treatment amp Analysisvol 7 no 2 p 237 2016

[46] D Ganguly S Patra P R Muduli et al ldquoInfluence of nutrientinput on the trophic state of a tropical brackish water lagoonrdquoJournal of Earth System Science vol 124 no 5 pp 1005ndash10172015

[47] J F LopesNVaz L Vaz J A Ferreira and JMDias ldquoAssessingthe state of the lower level of the trophic web of a temperatelagoon in situations of light or nutrient stress a modeling studyrdquoEcological Modelling vol 313 pp 59ndash76 2015

[48] N Zaaboub A Ounis M A Helali et al ldquoPhosphorusspeciation in sediments and assessment of nutrient exchangeat the water-sediment interface in a Mediterranean lagoonimplications for management and restorationrdquo EcologicalEngineering vol 73 pp 115ndash125 2014

[49] A Sfriso A Marcomini and B Pavoni ldquoRelationships be-tween macroalgal biomass and nutrient concentrations ina hypertrophic area of the Venice lagoonrdquo Marine Envi-ronmental Research vol 22 no 4 pp 297ndash312 1987


[50] K Reddy M M Fisher H Pant P Inglett and J R WhiteIndian River Lagoon Hydrodynamics and Water QualityModel Nutrient Storage and Transformations in SedimentsFinal Report Florida Department of Environmental Regu-lation Gainesville FL USA 2001

[51] A C Tyler K J McGlathery and I C Anderson ldquoMacro-algae mediation of dissolved organic nitrogen fluxes ina temperate coastal lagoonrdquo Estuarine Coastal and ShelfScience vol 53 no 2 pp 155ndash168 2001

[52] C Gilbert C Sigua and W A Tweedale ldquoWatershed scaleassessment of nitrogen and phosphorus loadings in the IndianRiver lagoon basin Floridardquo Journal of EnvironmentalManagement vol 67 no 4 pp 363ndash372 2003

[53] A C Redfield ldquoampe biological control of chemical factors inthe environmentrdquo American Scientist vol 46 pp 205ndash2221958

[54] C L Schelske M F Coveney F J Aldridge W F Kenneyand J E Cable ldquoWind or nutrients historic development ofhypereutrophy in Lake Apopka Florida Limnology and lakemanagementrdquo Archiv for HydrobiologiemdashAdvances in Lim-nology vol 55 pp 543ndash563 2000

[55] W K Dodds ldquoMisuse of inorganic N and soluble reactive Pconcentrations to indicate nutrient status of surface watersrdquoJournal of the North American Benthological Society vol 22no 2 pp 171ndash181 2003

[56] G D Gikas T Giannakopoulou and V Tsihrintzis ldquoWaterquality trends in a lagoon impacted by non-point sourcepollution after implementation of protective measuresrdquoHydrobiologia vol 563 no 1 pp 385ndash406 2006

[57] M Cantildeedo-Arguelles and M Rieradevall ldquoDisturbancecaused by freshwater releases of different magnitude on theaquatic macro invertebrate communities of two coastal la-goonsrdquo Estuarine Coastal and Shelf Science vol 88 no 2pp 190ndash198 2010

[58] M A Best A WWither and S Coates ldquoDissolved oxygen asa physico-chemical supporting element in the water frame-work directiverdquo Marine Pollution Bulletin vol 55 no 1ndash6pp 53ndash64 2007

[59] M Devlin S Painting and M Best ldquoSetting nutrientthresholds to support an ecological assessment based onnutrient enrichment potential primary production and un-desirable disturbancerdquo Marine Pollution Bulletin vol 55no 1ndash6 pp 65ndash73 2007

[60] European Environmental Agency Nutrients in TransitionalCoastal and Marine Waters Office for official publications ofthe European Communities Luxembourg 2009

[61] S Coelho S Gamito and A Perez-Ruzafa ldquoTrophic state ofFoz de Almargem coastal lagoon (Algarve South Portugal)based on the water quality and the phytoplankton commu-nityrdquo Estuarine Coastal and Shelf Science vol 71 no 1-2pp 218ndash231 2007

[62] H K Lotze H S Lenihan B J Bourque et al ldquoDepletiondegradation and recovery potential of estuaries and coastalseasrdquo Science vol 312 no 5781 pp 1806ndash1809 2006

[63] A Pusceddu A DellrsquoAnno M Fabiano and R DanovaroldquoQuantity and bioavailability of sediment organic matter assignatures of benthic trophic statusrdquoMarine Ecology ProgressSeries vol 375 pp 41ndash52 2009

[64] M M Alaoui and L Aleya ldquoAssessment of the eutrophicationof Al Massira reservoir (Morocco) by means of a survey of thebiogeochemical balance of phosphorusrdquo Hydrobiologiavol 297 no 1 pp 75ndash82 1995

[65] F Andrieux-Loyer X Philippon G Bally R KerouelA Youenou and J Le Grand ldquoPhosphorus dynamics and

bioavailability in sediments of the Penze Estuary (NWFrance) in relation to annual P-fluxes and occurrences ofAlexandrium Minutumrdquo Biogeochemistry vol 88 no 3pp 213ndash231 2008

[66] M A Helali N Zaaboub W Oueslati A Ayed and L AleyaldquoNutrient exchange and oxygen demand at the sedimentndashwater interface during dry and wet seasons off the MedjerdaRiver Delta (Tunis Gulf Tunisia)rdquo Environmental EarthSciences vol 75 no 1 p 25 2016


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Submit your manuscripts atwwwhindawicom

considered as the most eutrophicated lagoon on the Tunisiancoast [8ndash10]

In order to resolve the pollution problem and to improvethe water quality of the South Lagoon of Tunis (the southbasin of the lagoon of Tunis being the subject of our studies)for ecological and economical purposes an environmentalrestoration project was conducted from April 1998 to July2001 [11 12] ampe overall aim of the project was to achievea good ecological status in the lagoon and to realize sub-stantial land reclamation all around After this restorationwork the lagoon morphology has radically changed

ampe general aspect of the project was to increase theflushing power of the lagoon water with marine water fromthe Gulf of Tunis and to reduce the water residence timeampese purposes were reached by setting two groups of locks inorder to allow water exchange between the Gulf of Tunis andthe lagoon In order to avoid water stagnation different areaslocated in both the Southeast and the southwest side of thelagoon were removed (reducing the lagoon area from 13 km2

to 7 km2) and the shoreline was rectified to be straightenedMoreover polluted sediments were dredged and removedfrom the north area of the lagoon To improve water circu-lation fishery was removed and the Canal of Rades and theCanal of Tunis were restored [13 14]

Understanding the ecosystem response to this restora-tion project is essential to assess its rehabilitation ampe timeelapsed after restoration is a critical indicator of the realrestoration success [15] Indeed this coastal ecosystem re-covery requires a continuous survey through an ecologicaltrophic state evaluation

ampe assessment of the status of the lagoon after 16 years ofthe installation of the restoration works is much needed inorder to project further solutions for the decision makers Inthis study this assessment targetsmainly the nutrient elementsand the trophic index to see if the eutrophication of the lagoonhas been improved or otherwise To our knowledge this is theunique study which is addressing such problematic related tonutrient elements in relation to eutrophication within theLagoon of Tunis as previous investigations were conductedfrom a biological and hydrodynamic point of view only (algaemussels etc) However the trophic status has received littleattention and this research aims to overcome this gap

In this paper these investigations were conductedthroughout the lagoon to assess the restoration level andimprovement of water quality Furthermore we attempt toevaluate the trophic state of lagoon water for eutrophica-tionrsquos risk analysis after almost 16 years

Surface water samples were collected in wet and dryseasons (JulyFebruary) and then were analyzed Distribu-tion maps and plots of chemical parameters were used todetermine the geochemical characteristics of the lagoonwater and to identify major natural and anthropogenicprocesses governing water geochemistry

In addition multivariate statistical analysis such asprincipal component analysis (PCA) and hierarchical clusteranalysis (HCA) were used in order to help interpreting thecomplex data matrices for better understanding of the waterquality and to allow the identification of possible factors thatinfluence the water system [16ndash18]

It is widely recognized that the water quality assessmentin coastal ecosystems is complicated since a great number ofvariables including cause (nutrients) and response (chlo-rophyll a) variables are interrelated [19 20] Several methodsare thus used to characterize water quality and to assesseutrophication In this study the TRIX developed by Vol-lenweider et al [21] is used to estimate the trophic status ofthe lagoon water

2 Materials and Methods

21 Study Area ampe lagoon of Tunis is located in thenortheast of Tunisia Cutting across the lagoon and con-necting the Mediterranean with the old port of Tunis theCanal of Tunis divides the lagoon into two basins commonlyknown as the South Lake and the North Lake of Tunis

ampe South Lagoon of Tunis coordinates extend from 12prime to10deg16primeE longitudes and from 36deg46prime to 36deg48primeN latitudes(Figure 1) ampis area was used to be heavily polluted [8 22]but it has recently been rehabilitated [23] After the resto-ration program the lagoon appears shaped as an eclipsestretching in a SW-NE direction with about 10 km long and35 km wide (Figure 1) It extends over an area of 720 ha witha regular depth of about 21m except in some restricted areason the east side where it reaches amaximumof 5m Its shoresare rectilinear and protected by large rockery stones

ampe lagoon is characterized by a semiarid Mediterraneanclimate ampe annual temperature ranges between 7 and 30degCampe mean annual rainfall is 528mm with interannual var-iations ampe luminosity is about 6 h per day with 155 h inDecember and 359 h in July Evaporation ranges between 62and 201mm respectively in January and July [24]

Coastal lagoons maintain a connection to the seathrough a restricted inlet At the South Lagoon the waterflow between the lagoon and the Gulf of Tunis is impeded bytwo inlets (or outlets) seawater generally flows into thelagoon from the east side through the Canal of Rades (2 kmlength and 4m deep) and goes out from the western sidethrough the Canal of Tunis (10 km length and 45m deep)

ampe hydrodynamic of the lagoon is mainly controlledby wind and tide which is semidiurnal [23 25] ampe locksat Rades and Tunis are opened and closed in an alternativeway imposing a one-way water flow going from the east tothe west ampe average water residence time in the lagoonvaries from 66 to 82 days [25] ampe total exchange ofwater volume with the sea via the Canal of Rades is about257millionmiddotm3day ampe water speed of the lagoon is nothomogenous It varies from 65 cms to no more than5 cms going from the Canal of Rades to the canal ofNavigation leading to the appearance of little stagnationzones in the northwestern part of the lagoon [26](Figure 2)

ampe South Lagoon of Tunis has a drainage watershed of4000 ha where more than 1500 ha are industrial areas (foodindustries wholesale etc) [23] Rapid urbanization aroundthe lagoon during the past decade has resulted in a sub-stantial increase in the volume and pollutant load of thestorm-water and wastewater flowing into the lagoon ampelagoon receives water from draining the urban area of




Tunisia

Algeria Libiya

e Mediterranean Sea


36deg4

9prime0Prime

N36

deg48prime

0PrimeN

36deg4

7prime0Prime

N36

deg46prime

0PrimeN

36deg4

5prime0Prime

N

Canal of Tunis

Canal ofRades

Fichingport

Commercialport

Oldharbour

Rades

Megrine

Tunis

MegrineRiadh

Ben Arous



Gulf of Tunis


N


Forest


5000

4000

3000

2000

1000

01000 2000 3000 4000 5000 6000 7000

02 msMegrine

Canalof Rades


Canalof Tunis

(a)

Canalof Tunis


Canalof Rades

1000 2000 3000 4000 5000 6000

0

0

1000

500

1500

2000

2500

(b)














N

Gulf of Tunis

km21050

Canalof Rades

Megrine

Canal of TunisTunis

C14

C13

C8 C7

C6

C5

C2C3C4

C1C9

C10C12

C11

36deg49prime0PrimeN


36deg48prime0PrimeN




36deg46prime0PrimeN


36deg46prime0PrimeN


36deg47prime0PrimeN


36deg48prime0PrimeN



deg11prime3

0PrimeE

10deg1

2prime3

0PrimeE

10deg1

3prime3

0PrimeE

10deg1

4prime3

0PrimeE

10deg1

5prime3

0PrimeE

10deg1

6prime3

0PrimeE

10deg1

7prime3

0PrimeE

10deg1

8prime3

0PrimeE

10deg1

8prime3

0PrimeE

10deg1

8prime0Prime

E10

deg18prime

0PrimeE

10deg1

7prime0Prime

E10

deg17prime

0PrimeE

10deg1

7prime3

0PrimeE

10deg1

2prime3

0PrimeE

10deg1

1prime3

0PrimeE

10deg1

3prime3

0PrimeE

10deg1

6prime0Prime

E

10deg1

6prime3

0PrimeE

10deg1

6prime0Prime

E

10deg1

5prime0Prime

E

10deg1

5prime3

0PrimeE

10deg1

5prime0Prime

E

10deg1

2prime3

0PrimeE

10deg1

2prime0Prime

E

10deg1

3prime0Prime

E10

deg13prime

0PrimeE

10deg1

4prime0Prime

E10

deg14prime

0PrimeE

10deg1

4prime3

0PrimeE







b (1)





















Tabl

e1

Statistical

summaryof

physicochemical

parametersandnu

trientsin

SouthLagoon

ofTu

nis

Depth

(m)

T (deg C)

pHDO

(mgL)

Salin

ity(permil

)Con

ductivity

(Scm)

SPM

(mgL)

NH

4+

(mgL)

NO2minus

(mgL)

NO3minus

(mgL)

Ortho

-P(m

gL)

Chl-a

(microgL)

Pheo

(microgL)

Turbidity

(100

NTU

)Transparency

(m)

July

campaign

Minim

um2

288

848

3483

568

0025

0071

0079

9295

2129

1108

4424

813

Maxim

um54

30895

44

491

577

0043

0117

0095

14429

2409

3324

8759

242

Average

29

295

872

35

486

571

0034

0088

0087

11593

2275

2137

6230

157

15

February

campaign

Minim

um18

151

85

62

475

559

0019

0043

0550

3070

1601

0997

0598

115

Maxim

um42

175

894

11484

569

0032

0052

0901

15580

2958

2659

2726

918

Average

27

159

873

8481

566

0027

0046

0643

9423

1790

1994

1612

416

Gulfo

fTun

is(July)

mdash227

757

69

435

511

0244

011

1375

0465

Non

points

ource

mdash247

755

39

61

712

0291

0399

11063

1283

Pointsources

mdash247

763

39

518

518

0018

0063

11265

1243





July 2013


295ndash30

Gulf of Tunis

N

Gulf of Tunis

N

February 2014

15ndash155


Tem

pera

ture

(degC)

Gulf of Tunis

Salin

ity (permil

)

N


Gulf of Tunis

N


Gulf of Tunis

N

July 2013

86ndash8884ndash86

88ndash896

pH

Gulf of Tunis

N

February 2014

86ndash8884ndash86

88ndash89







minus





N

7ndash86ndash7

8ndash9


Diss

olve

d ox

ygen

(mg

L)N

3ndash35




N

km0 1


0ndash20

20ndash50

50ndash80

80ndash100



Gulf of Tunis

N

7ndash99ndash11

July 2013

11ndash1313ndash15

Gulf of Tunis

N

2ndash55ndash8

February 2014

8ndash1212ndash15

Gulf of Tunis

N


July 2013


Gulf of Tunis

N


February 2014


Gulf of Tunis

N

007-008008-009

July 2013

009-0101ndash011

Gulf of Tunis

N


February 2014


Gulf of Tunis

Nitr

ate (

mg

L)N

itrite

(mg

L)A

mm

oniu

m (m

gL)

Ort

ho-P

(mg

L)

N

July 2013

22-2321-22

23-24

Gulf of Tunis

N

February 2014

15ndash21ndash15

2ndash25











C1

C2

C3 C4C5

C6

C7

C8

C9

C10

C11

C12

C13

C14

2

21

22

23

24

25

9 10 11 12 13 14 15

Ort

ho-P

(mg

L)

DIN (mgL)

r2 = 013

July samples

(a)

C1C2 C3C4

C5

C6C7

C8 C9

C10

C11

C12

C13

C14

15

2

25

3

Ort

ho-P

(mg

L)

r2 = 040

2 4 6 8 10 12 14 16 18DIN (mgL)

February samples

(b)


02468

1012141618

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Ratio

DIN

ort

ho-P

Samples stations


Redfield ratio












15ndash2505ndash15

Gulf of Tunis

Chlo

roph

yll a

(microg

L)

15ndash209ndash15

Gulf of Tunis

N


N


1ndash1505ndash1

Gulf of Tunis

N

55ndash6545ndash55

Gulf of Tunis

Pheo

pigm

ants

(microg

L)



N





+ NO2minus NO3





















NO3minus 1 048 012 031 023 007













T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1


PC2

(13

97

)

PC1 (5465)


NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5


PC2

(13

97

)

PC1 (5465)


Group I

Group II



F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)










F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls






Tunisia

Algeria Libiya

e Mediterranean Sea


36deg4

9prime0Prime

N36

deg48prime

0PrimeN

36deg4

7prime0Prime

N36

deg46prime

0PrimeN

36deg4

5prime0Prime

N

Canal of Tunis

Canal ofRades

Fichingport

Commercialport

Oldharbour

Rades

Megrine

Tunis

MegrineRiadh

Ben Arous



Gulf of Tunis


N


Forest


5000

4000

3000

2000

1000

01000 2000 3000 4000 5000 6000 7000

02 msMegrine

Canalof Rades


Canalof Tunis

(a)

Canalof Tunis


Canalof Rades

1000 2000 3000 4000 5000 6000

0

0

1000

500

1500

2000

2500

(b)














N

Gulf of Tunis

km21050

Canalof Rades

Megrine

Canal of TunisTunis

C14

C13

C8 C7

C6

C5

C2C3C4

C1C9

C10C12

C11

36deg49prime0PrimeN


36deg48prime0PrimeN




36deg46prime0PrimeN


36deg46prime0PrimeN


36deg47prime0PrimeN


36deg48prime0PrimeN



deg11prime3

0PrimeE

10deg1

2prime3

0PrimeE

10deg1

3prime3

0PrimeE

10deg1

4prime3

0PrimeE

10deg1

5prime3

0PrimeE

10deg1

6prime3

0PrimeE

10deg1

7prime3

0PrimeE

10deg1

8prime3

0PrimeE

10deg1

8prime3

0PrimeE

10deg1

8prime0Prime

E10

deg18prime

0PrimeE

10deg1

7prime0Prime

E10

deg17prime

0PrimeE

10deg1

7prime3

0PrimeE

10deg1

2prime3

0PrimeE

10deg1

1prime3

0PrimeE

10deg1

3prime3

0PrimeE

10deg1

6prime0Prime

E

10deg1

6prime3

0PrimeE

10deg1

6prime0Prime

E

10deg1

5prime0Prime

E

10deg1

5prime3

0PrimeE

10deg1

5prime0Prime

E

10deg1

2prime3

0PrimeE

10deg1

2prime0Prime

E

10deg1

3prime0Prime

E10

deg13prime

0PrimeE

10deg1

4prime0Prime

E10

deg14prime

0PrimeE

10deg1

4prime3

0PrimeE







b (1)





















Tabl

e1

Statistical

summaryof

physicochemical

parametersandnu

trientsin

SouthLagoon

ofTu

nis

Depth

(m)

T (deg C)

pHDO

(mgL)

Salin

ity(permil

)Con

ductivity

(Scm)

SPM

(mgL)

NH

4+

(mgL)

NO2minus

(mgL)

NO3minus

(mgL)

Ortho

-P(m

gL)

Chl-a

(microgL)

Pheo

(microgL)

Turbidity

(100

NTU

)Transparency

(m)

July

campaign

Minim

um2

288

848

3483

568

0025

0071

0079

9295

2129

1108

4424

813

Maxim

um54

30895

44

491

577

0043

0117

0095

14429

2409

3324

8759

242

Average

29

295

872

35

486

571

0034

0088

0087

11593

2275

2137

6230

157

15

February

campaign

Minim

um18

151

85

62

475

559

0019

0043

0550

3070

1601

0997

0598

115

Maxim

um42

175

894

11484

569

0032

0052

0901

15580

2958

2659

2726

918

Average

27

159

873

8481

566

0027

0046

0643

9423

1790

1994

1612

416

Gulfo

fTun

is(July)

mdash227

757

69

435

511

0244

011

1375

0465

Non

points

ource

mdash247

755

39

61

712

0291

0399

11063

1283

Pointsources

mdash247

763

39

518

518

0018

0063

11265

1243





July 2013


295ndash30

Gulf of Tunis

N

Gulf of Tunis

N

February 2014

15ndash155


Tem

pera

ture

(degC)

Gulf of Tunis

Salin

ity (permil

)

N


Gulf of Tunis

N


Gulf of Tunis

N

July 2013

86ndash8884ndash86

88ndash896

pH

Gulf of Tunis

N

February 2014

86ndash8884ndash86

88ndash89







minus





N

7ndash86ndash7

8ndash9


Diss

olve

d ox

ygen

(mg

L)N

3ndash35




N

km0 1


0ndash20

20ndash50

50ndash80

80ndash100



Gulf of Tunis

N

7ndash99ndash11

July 2013

11ndash1313ndash15

Gulf of Tunis

N

2ndash55ndash8

February 2014

8ndash1212ndash15

Gulf of Tunis

N


July 2013


Gulf of Tunis

N


February 2014


Gulf of Tunis

N

007-008008-009

July 2013

009-0101ndash011

Gulf of Tunis

N


February 2014


Gulf of Tunis

Nitr

ate (

mg

L)N

itrite

(mg

L)A

mm

oniu

m (m

gL)

Ort

ho-P

(mg

L)

N

July 2013

22-2321-22

23-24

Gulf of Tunis

N

February 2014

15ndash21ndash15

2ndash25











C1

C2

C3 C4C5

C6

C7

C8

C9

C10

C11

C12

C13

C14

2

21

22

23

24

25

9 10 11 12 13 14 15

Ort

ho-P

(mg

L)

DIN (mgL)

r2 = 013

July samples

(a)

C1C2 C3C4

C5

C6C7

C8 C9

C10

C11

C12

C13

C14

15

2

25

3

Ort

ho-P

(mg

L)

r2 = 040

2 4 6 8 10 12 14 16 18DIN (mgL)

February samples

(b)


02468

1012141618

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Ratio

DIN

ort

ho-P

Samples stations


Redfield ratio












15ndash2505ndash15

Gulf of Tunis

Chlo

roph

yll a

(microg

L)

15ndash209ndash15

Gulf of Tunis

N


N


1ndash1505ndash1

Gulf of Tunis

N

55ndash6545ndash55

Gulf of Tunis

Pheo

pigm

ants

(microg

L)



N





+ NO2minus NO3





















NO3minus 1 048 012 031 023 007













T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1


PC2

(13

97

)

PC1 (5465)


NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5


PC2

(13

97

)

PC1 (5465)


Group I

Group II



F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)










F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls















N

Gulf of Tunis

km21050

Canalof Rades

Megrine

Canal of TunisTunis

C14

C13

C8 C7

C6

C5

C2C3C4

C1C9

C10C12

C11

36deg49prime0PrimeN


36deg48prime0PrimeN




36deg46prime0PrimeN


36deg46prime0PrimeN


36deg47prime0PrimeN


36deg48prime0PrimeN



deg11prime3

0PrimeE

10deg1

2prime3

0PrimeE

10deg1

3prime3

0PrimeE

10deg1

4prime3

0PrimeE

10deg1

5prime3

0PrimeE

10deg1

6prime3

0PrimeE

10deg1

7prime3

0PrimeE

10deg1

8prime3

0PrimeE

10deg1

8prime3

0PrimeE

10deg1

8prime0Prime

E10

deg18prime

0PrimeE

10deg1

7prime0Prime

E10

deg17prime

0PrimeE

10deg1

7prime3

0PrimeE

10deg1

2prime3

0PrimeE

10deg1

1prime3

0PrimeE

10deg1

3prime3

0PrimeE

10deg1

6prime0Prime

E

10deg1

6prime3

0PrimeE

10deg1

6prime0Prime

E

10deg1

5prime0Prime

E

10deg1

5prime3

0PrimeE

10deg1

5prime0Prime

E

10deg1

2prime3

0PrimeE

10deg1

2prime0Prime

E

10deg1

3prime0Prime

E10

deg13prime

0PrimeE

10deg1

4prime0Prime

E10

deg14prime

0PrimeE

10deg1

4prime3

0PrimeE







b (1)





















Tabl

e1

Statistical

summaryof

physicochemical

parametersandnu

trientsin

SouthLagoon

ofTu

nis

Depth

(m)

T (deg C)

pHDO

(mgL)

Salin

ity(permil

)Con

ductivity

(Scm)

SPM

(mgL)

NH

4+

(mgL)

NO2minus

(mgL)

NO3minus

(mgL)

Ortho

-P(m

gL)

Chl-a

(microgL)

Pheo

(microgL)

Turbidity

(100

NTU

)Transparency

(m)

July

campaign

Minim

um2

288

848

3483

568

0025

0071

0079

9295

2129

1108

4424

813

Maxim

um54

30895

44

491

577

0043

0117

0095

14429

2409

3324

8759

242

Average

29

295

872

35

486

571

0034

0088

0087

11593

2275

2137

6230

157

15

February

campaign

Minim

um18

151

85

62

475

559

0019

0043

0550

3070

1601

0997

0598

115

Maxim

um42

175

894

11484

569

0032

0052

0901

15580

2958

2659

2726

918

Average

27

159

873

8481

566

0027

0046

0643

9423

1790

1994

1612

416

Gulfo

fTun

is(July)

mdash227

757

69

435

511

0244

011

1375

0465

Non

points

ource

mdash247

755

39

61

712

0291

0399

11063

1283

Pointsources

mdash247

763

39

518

518

0018

0063

11265

1243





July 2013


295ndash30

Gulf of Tunis

N

Gulf of Tunis

N

February 2014

15ndash155


Tem

pera

ture

(degC)

Gulf of Tunis

Salin

ity (permil

)

N


Gulf of Tunis

N


Gulf of Tunis

N

July 2013

86ndash8884ndash86

88ndash896

pH

Gulf of Tunis

N

February 2014

86ndash8884ndash86

88ndash89







minus





N

7ndash86ndash7

8ndash9


Diss

olve

d ox

ygen

(mg

L)N

3ndash35




N

km0 1


0ndash20

20ndash50

50ndash80

80ndash100



Gulf of Tunis

N

7ndash99ndash11

July 2013

11ndash1313ndash15

Gulf of Tunis

N

2ndash55ndash8

February 2014

8ndash1212ndash15

Gulf of Tunis

N


July 2013


Gulf of Tunis

N


February 2014


Gulf of Tunis

N

007-008008-009

July 2013

009-0101ndash011

Gulf of Tunis

N


February 2014


Gulf of Tunis

Nitr

ate (

mg

L)N

itrite

(mg

L)A

mm

oniu

m (m

gL)

Ort

ho-P

(mg

L)

N

July 2013

22-2321-22

23-24

Gulf of Tunis

N

February 2014

15ndash21ndash15

2ndash25











C1

C2

C3 C4C5

C6

C7

C8

C9

C10

C11

C12

C13

C14

2

21

22

23

24

25

9 10 11 12 13 14 15

Ort

ho-P

(mg

L)

DIN (mgL)

r2 = 013

July samples

(a)

C1C2 C3C4

C5

C6C7

C8 C9

C10

C11

C12

C13

C14

15

2

25

3

Ort

ho-P

(mg

L)

r2 = 040

2 4 6 8 10 12 14 16 18DIN (mgL)

February samples

(b)


02468

1012141618

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Ratio

DIN

ort

ho-P

Samples stations


Redfield ratio












15ndash2505ndash15

Gulf of Tunis

Chlo

roph

yll a

(microg

L)

15ndash209ndash15

Gulf of Tunis

N


N


1ndash1505ndash1

Gulf of Tunis

N

55ndash6545ndash55

Gulf of Tunis

Pheo

pigm

ants

(microg

L)



N





+ NO2minus NO3





















NO3minus 1 048 012 031 023 007













T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1


PC2

(13

97

)

PC1 (5465)


NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5


PC2

(13

97

)

PC1 (5465)


Group I

Group II



F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)










F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls








b (1)





















Tabl

e1

Statistical

summaryof

physicochemical

parametersandnu

trientsin

SouthLagoon

ofTu

nis

Depth

(m)

T (deg C)

pHDO

(mgL)

Salin

ity(permil

)Con

ductivity

(Scm)

SPM

(mgL)

NH

4+

(mgL)

NO2minus

(mgL)

NO3minus

(mgL)

Ortho

-P(m

gL)

Chl-a

(microgL)

Pheo

(microgL)

Turbidity

(100

NTU

)Transparency

(m)

July

campaign

Minim

um2

288

848

3483

568

0025

0071

0079

9295

2129

1108

4424

813

Maxim

um54

30895

44

491

577

0043

0117

0095

14429

2409

3324

8759

242

Average

29

295

872

35

486

571

0034

0088

0087

11593

2275

2137

6230

157

15

February

campaign

Minim

um18

151

85

62

475

559

0019

0043

0550

3070

1601

0997

0598

115

Maxim

um42

175

894

11484

569

0032

0052

0901

15580

2958

2659

2726

918

Average

27

159

873

8481

566

0027

0046

0643

9423

1790

1994

1612

416

Gulfo

fTun

is(July)

mdash227

757

69

435

511

0244

011

1375

0465

Non

points

ource

mdash247

755

39

61

712

0291

0399

11063

1283

Pointsources

mdash247

763

39

518

518

0018

0063

11265

1243





July 2013


295ndash30

Gulf of Tunis

N

Gulf of Tunis

N

February 2014

15ndash155


Tem

pera

ture

(degC)

Gulf of Tunis

Salin

ity (permil

)

N


Gulf of Tunis

N


Gulf of Tunis

N

July 2013

86ndash8884ndash86

88ndash896

pH

Gulf of Tunis

N

February 2014

86ndash8884ndash86

88ndash89







minus





N

7ndash86ndash7

8ndash9


Diss

olve

d ox

ygen

(mg

L)N

3ndash35




N

km0 1


0ndash20

20ndash50

50ndash80

80ndash100



Gulf of Tunis

N

7ndash99ndash11

July 2013

11ndash1313ndash15

Gulf of Tunis

N

2ndash55ndash8

February 2014

8ndash1212ndash15

Gulf of Tunis

N


July 2013


Gulf of Tunis

N


February 2014


Gulf of Tunis

N

007-008008-009

July 2013

009-0101ndash011

Gulf of Tunis

N


February 2014


Gulf of Tunis

Nitr

ate (

mg

L)N

itrite

(mg

L)A

mm

oniu

m (m

gL)

Ort

ho-P

(mg

L)

N

July 2013

22-2321-22

23-24

Gulf of Tunis

N

February 2014

15ndash21ndash15

2ndash25











C1

C2

C3 C4C5

C6

C7

C8

C9

C10

C11

C12

C13

C14

2

21

22

23

24

25

9 10 11 12 13 14 15

Ort

ho-P

(mg

L)

DIN (mgL)

r2 = 013

July samples

(a)

C1C2 C3C4

C5

C6C7

C8 C9

C10

C11

C12

C13

C14

15

2

25

3

Ort

ho-P

(mg

L)

r2 = 040

2 4 6 8 10 12 14 16 18DIN (mgL)

February samples

(b)


02468

1012141618

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Ratio

DIN

ort

ho-P

Samples stations


Redfield ratio












15ndash2505ndash15

Gulf of Tunis

Chlo

roph

yll a

(microg

L)

15ndash209ndash15

Gulf of Tunis

N


N


1ndash1505ndash1

Gulf of Tunis

N

55ndash6545ndash55

Gulf of Tunis

Pheo

pigm

ants

(microg

L)



N





+ NO2minus NO3





















NO3minus 1 048 012 031 023 007













T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1


PC2

(13

97

)

PC1 (5465)


NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5


PC2

(13

97

)

PC1 (5465)


Group I

Group II



F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)










F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls




Tabl

e1

Statistical

summaryof

physicochemical

parametersandnu

trientsin

SouthLagoon

ofTu

nis

Depth

(m)

T (deg C)

pHDO

(mgL)

Salin

ity(permil

)Con

ductivity

(Scm)

SPM

(mgL)

NH

4+

(mgL)

NO2minus

(mgL)

NO3minus

(mgL)

Ortho

-P(m

gL)

Chl-a

(microgL)

Pheo

(microgL)

Turbidity

(100

NTU

)Transparency

(m)

July

campaign

Minim

um2

288

848

3483

568

0025

0071

0079

9295

2129

1108

4424

813

Maxim

um54

30895

44

491

577

0043

0117

0095

14429

2409

3324

8759

242

Average

29

295

872

35

486

571

0034

0088

0087

11593

2275

2137

6230

157

15

February

campaign

Minim

um18

151

85

62

475

559

0019

0043

0550

3070

1601

0997

0598

115

Maxim

um42

175

894

11484

569

0032

0052

0901

15580

2958

2659

2726

918

Average

27

159

873

8481

566

0027

0046

0643

9423

1790

1994

1612

416

Gulfo

fTun

is(July)

mdash227

757

69

435

511

0244

011

1375

0465

Non

points

ource

mdash247

755

39

61

712

0291

0399

11063

1283

Pointsources

mdash247

763

39

518

518

0018

0063

11265

1243





July 2013


295ndash30

Gulf of Tunis

N

Gulf of Tunis

N

February 2014

15ndash155


Tem

pera

ture

(degC)

Gulf of Tunis

Salin

ity (permil

)

N


Gulf of Tunis

N


Gulf of Tunis

N

July 2013

86ndash8884ndash86

88ndash896

pH

Gulf of Tunis

N

February 2014

86ndash8884ndash86

88ndash89







minus





N

7ndash86ndash7

8ndash9


Diss

olve

d ox

ygen

(mg

L)N

3ndash35




N

km0 1


0ndash20

20ndash50

50ndash80

80ndash100



Gulf of Tunis

N

7ndash99ndash11

July 2013

11ndash1313ndash15

Gulf of Tunis

N

2ndash55ndash8

February 2014

8ndash1212ndash15

Gulf of Tunis

N


July 2013


Gulf of Tunis

N


February 2014


Gulf of Tunis

N

007-008008-009

July 2013

009-0101ndash011

Gulf of Tunis

N


February 2014


Gulf of Tunis

Nitr

ate (

mg

L)N

itrite

(mg

L)A

mm

oniu

m (m

gL)

Ort

ho-P

(mg

L)

N

July 2013

22-2321-22

23-24

Gulf of Tunis

N

February 2014

15ndash21ndash15

2ndash25











C1

C2

C3 C4C5

C6

C7

C8

C9

C10

C11

C12

C13

C14

2

21

22

23

24

25

9 10 11 12 13 14 15

Ort

ho-P

(mg

L)

DIN (mgL)

r2 = 013

July samples

(a)

C1C2 C3C4

C5

C6C7

C8 C9

C10

C11

C12

C13

C14

15

2

25

3

Ort

ho-P

(mg

L)

r2 = 040

2 4 6 8 10 12 14 16 18DIN (mgL)

February samples

(b)


02468

1012141618

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Ratio

DIN

ort

ho-P

Samples stations


Redfield ratio












15ndash2505ndash15

Gulf of Tunis

Chlo

roph

yll a

(microg

L)

15ndash209ndash15

Gulf of Tunis

N


N


1ndash1505ndash1

Gulf of Tunis

N

55ndash6545ndash55

Gulf of Tunis

Pheo

pigm

ants

(microg

L)



N





+ NO2minus NO3





















NO3minus 1 048 012 031 023 007













T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1


PC2

(13

97

)

PC1 (5465)


NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5


PC2

(13

97

)

PC1 (5465)


Group I

Group II



F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)










F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls







July 2013


295ndash30

Gulf of Tunis

N

Gulf of Tunis

N

February 2014

15ndash155


Tem

pera

ture

(degC)

Gulf of Tunis

Salin

ity (permil

)

N


Gulf of Tunis

N


Gulf of Tunis

N

July 2013

86ndash8884ndash86

88ndash896

pH

Gulf of Tunis

N

February 2014

86ndash8884ndash86

88ndash89







minus





N

7ndash86ndash7

8ndash9


Diss

olve

d ox

ygen

(mg

L)N

3ndash35




N

km0 1


0ndash20

20ndash50

50ndash80

80ndash100



Gulf of Tunis

N

7ndash99ndash11

July 2013

11ndash1313ndash15

Gulf of Tunis

N

2ndash55ndash8

February 2014

8ndash1212ndash15

Gulf of Tunis

N


July 2013


Gulf of Tunis

N


February 2014


Gulf of Tunis

N

007-008008-009

July 2013

009-0101ndash011

Gulf of Tunis

N


February 2014


Gulf of Tunis

Nitr

ate (

mg

L)N

itrite

(mg

L)A

mm

oniu

m (m

gL)

Ort

ho-P

(mg

L)

N

July 2013

22-2321-22

23-24

Gulf of Tunis

N

February 2014

15ndash21ndash15

2ndash25











C1

C2

C3 C4C5

C6

C7

C8

C9

C10

C11

C12

C13

C14

2

21

22

23

24

25

9 10 11 12 13 14 15

Ort

ho-P

(mg

L)

DIN (mgL)

r2 = 013

July samples

(a)

C1C2 C3C4

C5

C6C7

C8 C9

C10

C11

C12

C13

C14

15

2

25

3

Ort

ho-P

(mg

L)

r2 = 040

2 4 6 8 10 12 14 16 18DIN (mgL)

February samples

(b)


02468

1012141618

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Ratio

DIN

ort

ho-P

Samples stations


Redfield ratio












15ndash2505ndash15

Gulf of Tunis

Chlo

roph

yll a

(microg

L)

15ndash209ndash15

Gulf of Tunis

N


N


1ndash1505ndash1

Gulf of Tunis

N

55ndash6545ndash55

Gulf of Tunis

Pheo

pigm

ants

(microg

L)



N





+ NO2minus NO3





















NO3minus 1 048 012 031 023 007













T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1


PC2

(13

97

)

PC1 (5465)


NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5


PC2

(13

97

)

PC1 (5465)


Group I

Group II



F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)










F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls








minus





N

7ndash86ndash7

8ndash9


Diss

olve

d ox

ygen

(mg

L)N

3ndash35




N

km0 1


0ndash20

20ndash50

50ndash80

80ndash100



Gulf of Tunis

N

7ndash99ndash11

July 2013

11ndash1313ndash15

Gulf of Tunis

N

2ndash55ndash8

February 2014

8ndash1212ndash15

Gulf of Tunis

N


July 2013


Gulf of Tunis

N


February 2014


Gulf of Tunis

N

007-008008-009

July 2013

009-0101ndash011

Gulf of Tunis

N


February 2014


Gulf of Tunis

Nitr

ate (

mg

L)N

itrite

(mg

L)A

mm

oniu

m (m

gL)

Ort

ho-P

(mg

L)

N

July 2013

22-2321-22

23-24

Gulf of Tunis

N

February 2014

15ndash21ndash15

2ndash25











C1

C2

C3 C4C5

C6

C7

C8

C9

C10

C11

C12

C13

C14

2

21

22

23

24

25

9 10 11 12 13 14 15

Ort

ho-P

(mg

L)

DIN (mgL)

r2 = 013

July samples

(a)

C1C2 C3C4

C5

C6C7

C8 C9

C10

C11

C12

C13

C14

15

2

25

3

Ort

ho-P

(mg

L)

r2 = 040

2 4 6 8 10 12 14 16 18DIN (mgL)

February samples

(b)


02468

1012141618

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Ratio

DIN

ort

ho-P

Samples stations


Redfield ratio












15ndash2505ndash15

Gulf of Tunis

Chlo

roph

yll a

(microg

L)

15ndash209ndash15

Gulf of Tunis

N


N


1ndash1505ndash1

Gulf of Tunis

N

55ndash6545ndash55

Gulf of Tunis

Pheo

pigm

ants

(microg

L)



N





+ NO2minus NO3





















NO3minus 1 048 012 031 023 007













T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1


PC2

(13

97

)

PC1 (5465)


NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5


PC2

(13

97

)

PC1 (5465)


Group I

Group II



F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)










F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls




Gulf of Tunis

N

7ndash99ndash11

July 2013

11ndash1313ndash15

Gulf of Tunis

N

2ndash55ndash8

February 2014

8ndash1212ndash15

Gulf of Tunis

N


July 2013


Gulf of Tunis

N


February 2014


Gulf of Tunis

N

007-008008-009

July 2013

009-0101ndash011

Gulf of Tunis

N


February 2014


Gulf of Tunis

Nitr

ate (

mg

L)N

itrite

(mg

L)A

mm

oniu

m (m

gL)

Ort

ho-P

(mg

L)

N

July 2013

22-2321-22

23-24

Gulf of Tunis

N

February 2014

15ndash21ndash15

2ndash25











C1

C2

C3 C4C5

C6

C7

C8

C9

C10

C11

C12

C13

C14

2

21

22

23

24

25

9 10 11 12 13 14 15

Ort

ho-P

(mg

L)

DIN (mgL)

r2 = 013

July samples

(a)

C1C2 C3C4

C5

C6C7

C8 C9

C10

C11

C12

C13

C14

15

2

25

3

Ort

ho-P

(mg

L)

r2 = 040

2 4 6 8 10 12 14 16 18DIN (mgL)

February samples

(b)


02468

1012141618

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Ratio

DIN

ort

ho-P

Samples stations


Redfield ratio












15ndash2505ndash15

Gulf of Tunis

Chlo

roph

yll a

(microg

L)

15ndash209ndash15

Gulf of Tunis

N


N


1ndash1505ndash1

Gulf of Tunis

N

55ndash6545ndash55

Gulf of Tunis

Pheo

pigm

ants

(microg

L)



N





+ NO2minus NO3





















NO3minus 1 048 012 031 023 007













T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1


PC2

(13

97

)

PC1 (5465)


NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5


PC2

(13

97

)

PC1 (5465)


Group I

Group II



F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)










F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls












C1

C2

C3 C4C5

C6

C7

C8

C9

C10

C11

C12

C13

C14

2

21

22

23

24

25

9 10 11 12 13 14 15

Ort

ho-P

(mg

L)

DIN (mgL)

r2 = 013

July samples

(a)

C1C2 C3C4

C5

C6C7

C8 C9

C10

C11

C12

C13

C14

15

2

25

3

Ort

ho-P

(mg

L)

r2 = 040

2 4 6 8 10 12 14 16 18DIN (mgL)

February samples

(b)


02468

1012141618

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Ratio

DIN

ort

ho-P

Samples stations


Redfield ratio












15ndash2505ndash15

Gulf of Tunis

Chlo

roph

yll a

(microg

L)

15ndash209ndash15

Gulf of Tunis

N


N


1ndash1505ndash1

Gulf of Tunis

N

55ndash6545ndash55

Gulf of Tunis

Pheo

pigm

ants

(microg

L)



N





+ NO2minus NO3





















NO3minus 1 048 012 031 023 007













T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1


PC2

(13

97

)

PC1 (5465)


NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5


PC2

(13

97

)

PC1 (5465)


Group I

Group II



F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)










F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls













15ndash2505ndash15

Gulf of Tunis

Chlo

roph

yll a

(microg

L)

15ndash209ndash15

Gulf of Tunis

N


N


1ndash1505ndash1

Gulf of Tunis

N

55ndash6545ndash55

Gulf of Tunis

Pheo

pigm

ants

(microg

L)



N





+ NO2minus NO3





















NO3minus 1 048 012 031 023 007













T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1


PC2

(13

97

)

PC1 (5465)


NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5


PC2

(13

97

)

PC1 (5465)


Group I

Group II



F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)










F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls






+ NO2minus NO3





















NO3minus 1 048 012 031 023 007













T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1


PC2

(13

97

)

PC1 (5465)


NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5


PC2

(13

97

)

PC1 (5465)


Group I

Group II



F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)










F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls









T (degC)

pH

DOSalinity

SPM

ndashNO2

NO3ndash

Ortho-PChl-a

PheoTurbidity

Transparency

ndash1

ndash05

0

05

1


PC2

(13

97

)

PC1 (5465)


NH4+

(a)

T (degC)

pH

DO

Salinity

SPM

Ortho-P

Chl-aPheo

Turbidity

Transparency

ndash1

ndash05

0

05

1


PC3

(95

2)

PC1 (5465)


NO3ndash

ndashNO2

NH4+

(b)

J-1

J-2

J-3

J-4J-14

J-5J-6

J-7

J-8

J-9J-10

J-11

J-12 J-13

F-1 F-2

F-4

F-5

F-6F-7

F-8F-9

F-11F-12F-13

F-14

T (degC)

pH

DOSalinity

SPM

Ortho-P

Chl-a

Pheo

Turbidity

Transparency

ndash3

ndash2

ndash1

0

1

2

3

4

5


PC2

(13

97

)

PC1 (5465)


Group I

Group II



F-3

F-10

ndashNO2

NH4+

NO3ndash

(c)










F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls











F-2F-3F-7F-1F-6F-9

F-12F-13

F-5F-10

F-4F-8

F-11F-14J-14

J-4J-9

J-11J-8

J-12J-1J-2J-3J-6J-5

J-13J-7

J-10

0 100 200 300 400 500

Samples

Dissimilarity2500




2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

TRIX

Samples stations


Poor

ModerateGoodHigh




4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls





4 Conclusion



NO2minus NH4





Data Availability


Disclosure




Acknowledgments


References














































































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls






























































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls




AssessmentoftheTrophicStatusoftheSouthLagoonof Tunis ...

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Transcript of AssessmentoftheTrophicStatusoftheSouthLagoonof Tunis ...