Light, Secchi, Weather and Miscellaneous Comments Liz Ely, Ira Smith, and Margaret Soulman.
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Transcript of Light, Secchi, Weather and Miscellaneous Comments Liz Ely, Ira Smith, and Margaret Soulman.
Light, Secchi, Weather and Miscellaneous Comments
Liz Ely, Ira Smith, and
Margaret Soulman
secchi depth for varous lakes
0
5
10
15
Lakes
De
pth
(m
)
Arbutus
Deer
Wolf
Green
Skaneateles
Onondaga
Oneida
ARBUTUS & ONEIDA LAKES
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 50 100 150 200 250 300 350 400 450
LIGHT
DE
PT
H(m
) DECK ARBUTUS
SPHERICAL ARBUTUS
DECK ONEIDA
SPHERICAL ONEIDA
GREEN LAKE
0
5
10
15
20
25
0 200 400 600 800 1000 1200 1400
LIGHT
DE
PT
H (
m)
DECK
SPHERICAL
SKANEATELES LAKE
0
10
20
30
40
50
60
0 200 400 600 800 1000 1200 1400 1600
LIGHT
DE
PT
H(m
)
DECK
SPHERICAL
DEER LAKE
0
0.5
1
1.5
2
2.5
3
3.5
0 100 200 300 400 500 600 700
LIGHT
DE
PT
H (
m)
DECK
SPHERICAL
Wolf Lake - Deck Cell Correction Example
Light Intensity (moles of quanta m-2 sec-1)
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Dep
th (
met
ers)
0
2
4
6
8
10
DECK vs DEPTH SPHERICAL vs DEPTH corrected spherical vs DEPTH
Green Lake Light Extinction Calculation
0
5
10
0 5 10 15 20 25
Depth
Ln (l
ight
)
r2=0.88
Arbutus Light Extinction Calculation
0
2
4
6
0 1 2 3 4 5
Depth
Ln
(Lig
ht)
r2=0.999
Light Extinction Coefficient
0
0.2
0.4
0.60.8
1
1.2
1.4
Arbut
usDee
r
Green
Oneida
Onond
aga
Skane
ateles W
olf
Lake
Lig
ht
Ex
tin
cti
on
Co
eff
icie
nt
(light extinction coefficients fixed now)
Secchi and Light Extinction Coefficient Comparison
Onondaga Oneida Deer Arbutus Wolf Green Skaneateles
Y D
ata
0
2
4
6
8
10
12
Light Extinction Secchi
Secchi versus Light Extinction
Secchi Depth
0 2 4 6 8 10 12
Lig
ht
Ext
inct
ion
Co
effi
cien
t
0
1
2
r2=0.90
YSI Group
Chris Hotaling
Nicole Hotaling
Rosa
YSI data
• Five parameters:– Depth, temp., pH, conductivity,
dissolved oxygen
• Measured on multiprobe• Graphed actual data (adjusted depth)
YSI Parameters
• Depth – Basin morphometry: nutrients, chemistry, heat
balance, productivity, habitat
• Temperature– stratification, organism distribution
• pH – measure of H+ concentration– chemical forms, organism response
YSI Parameters
• Conductivity – measure of ability to carry an electric current– Indicates ionic content, basin geology
• Dissolved Oxygen – Respiration, chemical form
Temperature (C)
0
5
10
15
20
25
30
35
40
45
50
5 7 9 11 13 15 17 19
dept
h (m
)
Deer
Wolf
Arbutus
Onon
Oneida
Green
Skan02
pH
0
5
10
15
20
25
30
35
40
45
50
6 6.5 7 7.5 8 8.5 9 9.5 10
dept
h (m
)
Deer
Wolf
Arbutus
Onon
Oneida
Green
Skan02
Conductivity (uS/cm)
0
5
10
15
20
25
30
35
40
45
50
0 10 20 30
dept
h (m
) Deer
Wolf
Arbutus
Oneida
Conductivity (uS/cm)
0
5
10
15
20
25
30
35
40
45
50
1400 1500 1600 1700 1800 1900 2000 2100 2200
dept
h (m
)
Onon
Green
DO (mg/L)
0
5
10
15
20
25
30
35
40
45
50
0 5 10 15 20
dept
h (m
)
Deer
Wolf
Arbutus
Onon
Green
Skan02
%DO
0
5
10
15
20
25
30
35
40
45
50
0 20 40 60 80 100 120 140 160 180 200
dept
h (m
)
Deer
Wolf
Arbutus
Oneida
Green
Whole Lake
• Adirondack lakes – shallow, lower pH (but not acidic), low conductivity, moderate DO
• Green, Skaneateles – deep, pH/cond reflects watershed geology
• Onondaga, Oneida – productive, pH/cond reflect different geology
What else?
• Could measure:– Specific conductance, salinity, redox potential,
recent weather patterns
• Error?– Zero depth, Onon/Oneida depths
Nutrients
Sampling techniques:
• strata depths were determined from temperature profile
• water samples were obtained using Kimmerer bottle
• three 1 L bottles were filled (1 each from epi, meta, hypo)
Analysis:
• phosphorus, nitrogen, silica
• dissolved nutrients is target, but acid-digestion in P and Si analyses may release nutrients from particles if sample is not filtered, leading to over-estimate of dissolved concentration
Phosphorous• The key controlling nutrient in freshwater systems
• Adding Phosphorous to a system increasing its productivity
• Deeper lakes will dilute Phosphorous
• In the presence of oxygen Fe3+ binds with and ‘traps’ phosphate
• If the hypolimnion is anoxic phosphorous will be released
• Rooted aquatic macrophytes take phosphorous up from sediments and releases it into water
Sources of Phosphorous
• Precipitation (dust in the air)
• Groundwater (small) adsorbs to soil particulates
• Surface runoff
• Weathering of calcium phosphate minerals (e.g.. Apatite)
- slow process
Anthropogenic Sources
• Point Source – sewage, industry, faulty septic systems, urban runoff
• Non-point Source – agriculture, animal waste
Phosphorous
>100Hypereutrophic
30-100Eutrophic
10-30Mesotrophic
5-10Oligotrophic
<5Ultra-Oligotrophic
Total Phosphorous ( g/L)
Lake Productivity
Eutrophication – increased growth of biota of lakes and the rate of productivity is higher than would have occurredwithout any disturbances.
Phosphorous – Total Phosphorous
Total Phosphorus
0
5
10
15
20
25
30
0 2 4 6 8 10 12 14 16
Concentration (umol/L)
Dep
th (
m)
Green
Onondaga
Oneida
Wolf
Arbutus
Deer
Phosphorous – Total Phosphorous
Lower Values of Total Phosphorus
0
2
4
6
8
10
0 1 2 3 4 5 6
Concentration (umol/L)
Dep
th (
m)
Green
Onondaga
Oneida
Wolf
Arbutus
Deer
Phosphorous – Total Dissolved Phosphorous
Total Dissolved Phosphorus
0
5
10
15
20
25
30
0 1 2 3 4 5
Concentration (umol/L)
Dep
th (
m)
Green
Onondaga
Oneida
Wolf
Arbutus
Deer
Phosphorous – Total Dissolved Phosphorous
Lower Values of Total Dissolved Phosphorus
0
2
4
6
8
10
0 0.2 0.4 0.6 0.8 1
Concentration (umol/L)
De
pth
(m
)
Green
Onondaga
Oneida
Wolf
Arbutus
Deer
Phosphorous Conclusions• Onondaga Lake considered hypereutrophic and had a
much higher phosphorous content than the other lakes contributing to noxious algal blooms
• Oneida has been eutrophic for over 350 years and is the next highest phosphorous values next to Onondaga Lake although there is a very large gap
• Wolf Lake is oligotrophic with plenty of oxygen throughout, this allows the phosphorous to be trapped by Fe3+ in the hypolimnion
Phosphorous Conclusions• Arbutus Lake near oligotrophic, and followed expected
pattern for P
• Deer Lake - P values seem to do the opposite of expected - possibly due to errors in sampling, such as brushing bottom sediments during sampling
• Green Lake is very oligotrophic, although the phosphorous concentrations follow those of a lake with anoxic bottom waters due to it being meromictic. Nutrients are entrained in bottom layers, so little in upper layers.
Lake Comparisons: Chemistry
Nitrogen
Sources of Nitrogen in the Water
• Inorganic nitrogen– Nitrate– Ammonia
• Organic nitrogen– Organisms– Dissolved Organic
General Nitrogen Distribution Within Water Column
• Surface waters– Increased organic nitrogen
• Buildup of phytoplankton– Decrease inorganic nitrogen
• Assimilated by phytoplankton
• Bottom waters – Increased organic and inorganic
• Lack of phytoplankton to assimilate inorganic• Settling of organic material• However, denitrification can convert inorganic to N gas
Total Nitrogen
0
5
10
15
20
25
30
0 20 40 60 80 100 120 140 160
Concentration (umol/L)
De
pth
(m
) Green
Onondaga
Oneida
Wolf
Arbutus
Deer
Lower Values of Total Nitrogen
0
2
4
6
8
10
0 5 10 15 20 25 30
Concentration (umol/L)
De
pth
(m
) Green
Onondaga
Oneida
Wolf
Arbutus
Deer
Total Dissolved Nitrogen
0
5
10
15
20
25
30
0 25 50 75 100 125 150 175
Concentration (umol/L)
De
pth
(m
)
Green
Onondaga
Oneida
Wolf
Arbutus
Deer
Lower Values for Total Dissolved Nitrogen
0
1
2
3
4
5
6
7
8
9
10
10 12 14 16 18 20 22 24
Concentration (umol/L)
De
pth
(m
)
Green
Onondaga
Oneida
Wolf
Arbutus
Deer
Nitrogen Conclusions
• Lakes show different nitrogen distributions– Cyanobacteria: present or absent?
• Nitrogen fixers– Elevate organic nitrogen levels
» Epilimnion or metalimnion (stratification effects)
– Turnover• Nitrogen levels tend toward uniform
– Denitrification in bottom waters• Due to low oxygen in bottom waters (Eutrophic?)
Silica in the Water Column
Dissolved:- silicic acids
Particulate:- diatoms- organic complexes- adhered to inorganic particles
Silica in the Water Column
Major source: - degraded alumino-silicate minerals
Solubility:- increased by humic compounds
Typical Profile:- biogenic reduction of dissolved silica in the epilimnion during early summer, and low epilimnetic silica maintained throughout summer
Cause: - intensive assimilation of silica by diatoms, and a greater rate of diatom sedimentation than rate of silica replenishment from sources
Expected silica profile (Wetzel)E
Silica
0
5
10
15
20
25
30
0 10 20 30 40 50 60 70
Concentration (umol/L)
Dep
th (
m)
Green
Onondaga
Wolf
Arbutus
Deer
DISSOLVED SILICA: Sep-Oct, 2003
Annual Cycle:
Lake inDenmark(Wetzel)
Why Opposite of Expected Silica Trends?
• Possible explanations?
- diatom bloom in epilimnion after turnover?
- samples were not sufficiently filtered, so [Si] reflects acid-dissolved diatoms as well as dissolved silica?
- runoff after rains from soils high in siliceaous materials
- or, data were recorded in reverse order