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Investigation of molecular markers to identify sources of nitrate contamination in groundwater Mitchell-Parsotan, Margaret Ann
Abstract
Molecular markers were investigated as potential tools for differentiating between the sources of elevated nitrate-N in the Hopington AB Aquifer. Residential use (septic systems) and agriculture (livestock) have been identified as key land use activities, which overlay the Hopington AB Aquifer, and thus possible contributors of nitrate-N to the groundwater. Harmful levels of nitrate-N concentrations above the drinking water limit of 10 mg/L have been detected in the well of a private resident (14 mg/L) and spring water (17 mg/L), which were located on the aquifer. DAS 1 (a diaminostilbene) and DSBP (a distyrylbiphenyl) are fluorescent whitening agents (FWAs), which in the Fraser Valley are present in 3 out of 4 popular laundry detergents, and have been detected in domestic wastewater at concentrations of 7.84 and 2.36 μg/L respectively; thus they are suitable markers for septic systems in Langley. Sulfamethazine, which is an antimicrobial approved solely for veterinary use in Canada, is widely used in the livestock industry. Good maximum recoveries for DAS 1 (60%), DSBP (125%) and sulfamethazine (125%), coupled with low method detection limits ranging from of 0.01 — 0.04 μg/L implied that solid phase extraction (SPE) and high-performance liquid chromatography (HPLC) with an ultra violet (UV) detector were adequate for the determination of the molecular markers. The detection of DAS 1 (3.14 μg/L) and DSBP (0.05 μg/L) in the final effluent at a BNR (biological nutrient removal) pilot plant suggested that the FWAs were not completely removed by wastewater treatment processes including primary clarification, biological (aerobic and anaerobic), and membrane filtration; thus, once released, these FWAs may persists in the environment. In this study, DAS 1 (0.01 — 0.13 μg/L) was detected in 4 wells belonging to private residences, which were located on the Hopington Aquifer. DAS 1 (0.05 μg/L) and DSBP (0.02 μg/L) were also detected in spring water, which were located down gradient of septic systems. These results suggested that septic tank systems have contributed to the overall nitrate in the aquifers. The non-detection of the FWAs at the two control sites (Hopington C and Abbottsford) confirmed the specificity of DAS 1 and DSBP in relation to source. Overall, the FWAs exhibited fairly conservative behaviours due to their abilities to be source specific and persistent in the environment. As a result, they are useful tools for the identification of septic system sources of contamination in the environment. Sulfamethazine was not detected in any of the Hopington AB wells; however, further research is needed in order to determine if this antimicrobial was an appropriate molecular marker for livestock activities.
Item Metadata
Title |
Investigation of molecular markers to identify sources of nitrate contamination in groundwater
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Creator | |
Publisher |
University of British Columbia
|
Date Issued |
2009
|
Description |
Molecular markers were investigated as potential tools for differentiating between the sources of
elevated nitrate-N in the Hopington AB Aquifer. Residential use (septic systems) and
agriculture (livestock) have been identified as key land use activities, which overlay the
Hopington AB Aquifer, and thus possible contributors of nitrate-N to the groundwater.
Harmful levels of nitrate-N concentrations above the drinking water limit of 10 mg/L have been
detected in the well of a private resident (14 mg/L) and spring water (17 mg/L), which were
located on the aquifer.
DAS 1 (a diaminostilbene) and DSBP (a distyrylbiphenyl) are fluorescent whitening agents
(FWAs), which in the Fraser Valley are present in 3 out of 4 popular laundry detergents, and
have been detected in domestic wastewater at concentrations of 7.84 and 2.36 μg/L respectively;
thus they are suitable markers for septic systems in Langley. Sulfamethazine, which is an
antimicrobial approved solely for veterinary use in Canada, is widely used in the livestock
industry.
Good maximum recoveries for DAS 1 (60%), DSBP (125%) and sulfamethazine (125%),
coupled with low method detection limits ranging from of 0.01 — 0.04 μg/L implied that solid
phase extraction (SPE) and high-performance liquid chromatography (HPLC) with an ultra
violet (UV) detector were adequate for the determination of the molecular markers.
The detection of DAS 1 (3.14 μg/L) and DSBP (0.05 μg/L) in the final effluent at a BNR
(biological nutrient removal) pilot plant suggested that the FWAs were not completely removed
by wastewater treatment processes including primary clarification, biological (aerobic and
anaerobic), and membrane filtration; thus, once released, these FWAs may persists in the
environment. In this study, DAS 1 (0.01 — 0.13 μg/L) was detected in 4 wells belonging to
private residences, which were located on the Hopington Aquifer. DAS 1 (0.05 μg/L) and DSBP
(0.02 μg/L) were also detected in spring water, which were located down gradient of septic
systems. These results suggested that septic tank systems have contributed to the overall nitrate
in the aquifers. The non-detection of the FWAs at the two control sites (Hopington C and
Abbottsford) confirmed the specificity of DAS 1 and DSBP in relation to source. Overall, the FWAs exhibited fairly conservative behaviours due to their abilities to be source
specific and persistent in the environment. As a result, they are useful tools for the
identification of septic system sources of contamination in the environment. Sulfamethazine
was not detected in any of the Hopington AB wells; however, further research is needed in order
to determine if this antimicrobial was an appropriate molecular marker for livestock activities.
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Extent |
5091085 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-04-27
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0063126
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2009-05
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Item Citations and Data
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International