Contaminated land: dealing with hydrocarbon contamination
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Transcript of Contaminated land: dealing with hydrocarbon contamination
Contaminated land: dealing Contaminated land: dealing with hydrocarbon with hydrocarbon
contaminationcontamination
Petroleum hydrocarbons – Petroleum hydrocarbons – occurrence, composition and occurrence, composition and
significance significance
Environmental Simulations International
Contents of Contents of presentation presentation
Sources of hydrocarbon Sources of hydrocarbon contaminationcontamination
Composition of oilsComposition of oils Non-hydrocarbon components of oilNon-hydrocarbon components of oil Hydrocarbon behaviour in the Hydrocarbon behaviour in the
subsurfacesubsurface The most important components?The most important components?
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Potential hydrocarbon-Potential hydrocarbon-contaminated sites – 1contaminated sites – 1
Stating the obviousStating the obvious– Filling stations, distribution depotsFilling stations, distribution depots– Oil production, refineries and Oil production, refineries and
associatedassociated– Garages/automotive industryGarages/automotive industry– Haulage yardsHaulage yards– Scrap metal industryScrap metal industry– Airports, aerospace industryAirports, aerospace industry– Waste processing & disposalWaste processing & disposal
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Potential hydrocarbon-Potential hydrocarbon-contaminated sites – 2contaminated sites – 2
And also…And also…– GasworksGasworks– Metalworking industryMetalworking industry– Paints/inks/coatings industryPaints/inks/coatings industry– Anybody who uses solvents!Anybody who uses solvents!– Agricultural facilitiesAgricultural facilities– Anywhere with a boilerhouse/ Anywhere with a boilerhouse/
furnacefurnace Including domestic oil storageIncluding domestic oil storage
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Composition of oilsComposition of oils
Crude oil and petroleum products Crude oil and petroleum products are complex mixturesare complex mixtures
They are characterised by differing They are characterised by differing boiling point ranges and boiling point ranges and componentscomponents– Carbon numbers/simulated distillationCarbon numbers/simulated distillation
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Oil refiningOil refining
CrudeOil
Gasoline C4-C10 (80oC - 150oC)
Kerosene/Jet Fuel C11-C13 (150oC - 250oC)
Diesel Fuel C14-C18 (250oC - 325oC)
Heavy Gas Oil C19-C25 (325oC - 450oC)
Lubricating Oil C26-C40 (450oC - 500oC)
Residuum >C40 (> 500oC)
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Main component Main component groupsgroups
Aliphatic hydrocarbonsAliphatic hydrocarbons Aromatic hydrocarbonsAromatic hydrocarbons NSO componentsNSO components
– Nitrogen, sulphur and oxygen-Nitrogen, sulphur and oxygen-containing compoundscontaining compounds
– ““Polar components”Polar components”– ““Asphaltenes”Asphaltenes”
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Aliphatic hydrocarbonsAliphatic hydrocarbons
Alkanes Saturated hydrocarbons - no double or triple bonds.(Paraffins)
Hexane
Alkenes/ Unsaturated hydrocarbons - double/triple bonds.Alkynes(Olefins)
Hexene
Cycloalkanes Saturated hydrocarbons with a ring structure.(Naphthenes)
Cyclohexane
C C C C C C
C C C C C C
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Aromatic hydrocarbons Aromatic hydrocarbons - BTEX- BTEX
Benzene o-Xylene C6H6 C8H11
Toluene m-Xylene C7H8 C8H11
Ethylbenzene p-Xylene C8H10 C8H11
CH3 CH3
CH3
CH3
CH3
CH3
CH3
CH2CH3
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Aromatic hydrocarbons Aromatic hydrocarbons – PAH’s– PAH’s
Polycyclic aromatic hydrocarbons (PAH)[polynuclear aromatic hydrocarbons (PNA)]
Naphthalene Benzo(a)PyreneC10H8 C20H12
PhenanthreneDibenzo(a,h)AnthraceneC14H10 C22H14
Pyrene FluorantheneC16H10 C16H10
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Relative distribution of Relative distribution of components – an components – an exampleexample
C2-
C4
C4-
C6
C6-
C8
C8-
C10
C10
-C12
C12
-C14
C14
-C16
C16
-C18
C18
-C20
C20
-C22
C22
-C24
C24
-C26
C26
-C28
C28
-C30
C30
-C32
C32
-C34
C34
-C36
>C36
05
1015
2025
30
35
40
Wei
gh
t P
erce
nt
Carbon Number
Crude
Diesel
Gasoline
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Hydrocarbon Hydrocarbon behaviour in the behaviour in the subsurfacesubsurface
Oil is a light non-aqueous phase liquid Oil is a light non-aqueous phase liquid (LNAPL)(LNAPL)– Residual oil will be held in pore spaces in soilResidual oil will be held in pore spaces in soil– Free oil “floats” on groundwaterFree oil “floats” on groundwater
The more soluble components can dissolve The more soluble components can dissolve in groundwaterin groundwater– MTBE & TAME are highly solubleMTBE & TAME are highly soluble
The more volatile components can partition The more volatile components can partition into soil gasinto soil gas
Sorption of components into/onto soil can be Sorption of components into/onto soil can be an important processan important process
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Before Oil Flow Through Soil
During Oil Flow Through Soil
After Oil Flow Through Soilcapillary fringe
water table
soil surface
vadosezone
saturated zone
PetrolSpill
groundwater flow
Residual Hydrocarbons in Soil Pores
(soil contamination)
(~1% HC by weight)
Mobile & ResidualHydrocarbons(free-product)
(~9% by weight)
Volatilised Constituents
(vapour plume)
(~50mg HC/kg soil)
(~130 mg HC/L water)
Dissolved Constituents (plume)
How oil components How oil components might be distributedmight be distributed
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NAPL – how?NAPL – how?
Oil in closed-end pore Residual oil trapped by water
Soil Matrix
Trapped NAPL
NAPL
Soil Matrix
Wetting Fluid (water)
NAPL
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Why is NAPL Why is NAPL important?important?
Direct effects of oil at receptorDirect effects of oil at receptor– Also potential effect on buried materialsAlso potential effect on buried materials
Residual NAPL can also be a source of Residual NAPL can also be a source of contamination for long periods of contamination for long periods of timetime– Water soluble components can cause Water soluble components can cause
long-term groundwater plumes long-term groundwater plumes – Volatile components are a potential Volatile components are a potential
source of vapourssource of vapours
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Petroleum Petroleum contamination – what contamination – what to look forto look for
Liquid phase (free-product NAPL) Liquid phase (free-product NAPL) Dissolved phase (groundwater Dissolved phase (groundwater
plume) plume) Solid phase (hydrocarbon attached Solid phase (hydrocarbon attached
to soil)to soil) Vapour phaseVapour phase Combination of several phasesCombination of several phases
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How oil components How oil components might be distributed – might be distributed – exampleexample
0% 20% 40% 60% 80% 100%
ACENAPHTHENE
ACENAPHTHYLENE
2-METHYLNAPHTHALENE
NAPHYTHALENE
o-XYLENE
ETHYLBENZENE
p-XYLENE
m-XYLENE
TOLUENE
BENZENE
Vapour
Water
Sorbed
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Non-hydrocarbon Non-hydrocarbon componentscomponents
Organic additivesOrganic additives– Petrol (gasoline): MTBE, TAMEPetrol (gasoline): MTBE, TAME– Fuels: proprietary performance additivesFuels: proprietary performance additives– Luboils: proprietary performance additivesLuboils: proprietary performance additives
MetalsMetals– Naturally occurring components of crudeNaturally occurring components of crude
e.g., vanadium, nickele.g., vanadium, nickel
– Significant contaminants in waste luboilsSignificant contaminants in waste luboils– Leaded petrol (TEL)Leaded petrol (TEL)
Max. 0.013 g/l in 1980’s leaded petrol but earlier or Max. 0.013 g/l in 1980’s leaded petrol but earlier or special use petrol could be higherspecial use petrol could be higher
– Proprietary performance additivesProprietary performance additives
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MTBE Methyl tertiary butyl ether
CH3
CCH3O
CH3
CH3
Additives in unleaded Additives in unleaded petrolpetrol
TAMETertiary methyl amyl ether
C2H5
CCH3O
CH3
CH3
ETBE Ethyl tertiary butyl ether
CH3
CCH2CH3O
CH3
CH3
• MTBE most common in UK• Typically 1-5% in petrol• Highly soluble (26000 mg/l)• Very low taste/odour threshold
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WeatheringWeathering
Preferential reduction in the concentration Preferential reduction in the concentration of some components relative to othersof some components relative to others– Biodegradation tends to favour removal of n-Biodegradation tends to favour removal of n-
alkanes (straight carbon chain alkanes), low alkanes (straight carbon chain alkanes), low molecular weight cycloalkanes and light molecular weight cycloalkanes and light aromaticsaromatics
– Volatilisation and dissolution tends to remove Volatilisation and dissolution tends to remove low molecular weight aromatics (especially low molecular weight aromatics (especially BTEX) and aliphaticsBTEX) and aliphatics
– Dissolution is very important for MTBE and Dissolution is very important for MTBE and TAMETAME
Weathering of organic lead additivesWeathering of organic lead additives
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Weathering – aliphatic Weathering – aliphatic componentscomponents
So, weathered So, weathered hydrocarbon mixtures hydrocarbon mixtures are typically are typically significantly less significantly less mobile and less toxic mobile and less toxic than “fresh” mixtures than “fresh” mixtures
C15
C20C25
C30
10
20
30
0
Wt%
n- iso- cyclo-
10
20
30
0
Wt%
n- iso- cyclo-
10
20
30
0
Wt%
2 6-rings4
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SummarySummary
Hydrocarbon contamination may arise Hydrocarbon contamination may arise at a wide variety of sitesat a wide variety of sites
Crude oils and petroleum products are Crude oils and petroleum products are complex mixtures of componentscomplex mixtures of components– We will discuss the implications further in We will discuss the implications further in
more detailmore detail Multiphase behaviour must be Multiphase behaviour must be
consideredconsidered Weathering may be importantWeathering may be important
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The most important The most important components?components?
Certain groups of components often Certain groups of components often merit particular (but not sole) merit particular (but not sole) consideration, e.g.consideration, e.g.– BTEXBTEX
Toxicity, vapoursToxicity, vapours
– PAH’sPAH’s Potential carcinogenicity, relatively persistentPotential carcinogenicity, relatively persistent
BUT this depends on the source-pathway-BUT this depends on the source-pathway-receptor relationships that you are receptor relationships that you are consideringconsidering– Is the conceptual model sound?Is the conceptual model sound?