TY - JOUR
T1 - Hydrochemical and stable isotopic assessment of nitrate contamination in an alluvial aquifer underneath a riverside agricultural field
AU - Chae, Gi Tak
AU - Yun, Seong Taek
AU - Mayer, Bernhard
AU - Choi, Byoung Young
AU - Kim, Kyoung Ho
AU - Kwon, Jang Soon
AU - Yu, Soon Young
N1 - Funding Information:
This work was supported by Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea Government (MEST) (No. R01-2007-000-20964-0 ). The initial stage of field campaigns for this study was also supported by the Environmental Geosphere Research Lab (EGRL) of Korea University. The authors thank many students at Korea University for their field and lab assistance. This paper was significantly clarified and improved by constructive comments from Dr. Rodney H. Grapes (Korea Univ.) and the two anonymous reviewers.
Copyright:
Copyright 2009 Elsevier B.V., All rights reserved.
PY - 2009/12
Y1 - 2009/12
N2 - Major ions and stable isotopic (δDwater, δ18Owater, δ15Nnitrate, δ18Onitrate) measurements in concert with hydrochemical modeling were used in order to elucidate the sources and geochemical processes controlling nitrate contamination of shallow alluvial groundwater underneath a riverside agricultural field in the Buyeo area, Korea. Beneath vegetable fields in the sandy soil, the mean nitrate concentration of groundwater was 148.6 mg/L, which is significantly higher than in groundwater (mean 28.8 mg/L) beneath silty soils underneath rice paddy fields. Nitrogen isotope data indicate that synthetic fertilizers are the predominant source of groundwater nitrate in the study area. Denitrification during recharge through rice paddy soils appears to be responsible for the lower nitrate concentrations in groundwater beneath the silty soil zone. The relationship between nitrogen and oxygen isotope data of nitrate also suggests mixing of two different groundwater bodies with nitrates from the silt zone and the sand zone. Geochemical mass balance modeling on hydrochemical data indicates that various agricultural chemicals such as urea, lime, magnesium sulfate and potassium chloride dissolve in vegetable fields of the sandy zone, resulting in significant enrichment of various solutes such as K+, Ca2+, Mg2+, NO3-, SO42- and Cl-. As a consequence of over-utilization of synthetic nitrogen fertilizers, the sand zone is characterized by very high nitrate concentrations in the groundwater. This study suggests that a reduction of over-fertilization especially on vegetable fields in the riverside sand zone is required to minimize the nitrate contamination of groundwater. This study also shows that combination of geochemical and isotopic techniques with simple mass balance modeling provides information about the causes and processes of nitrate contamination of groundwater underneath a riverside agricultural field. The study also provides sustainable measures to optimize fertilization rate as an important basis of eco-friendly agriculture.
AB - Major ions and stable isotopic (δDwater, δ18Owater, δ15Nnitrate, δ18Onitrate) measurements in concert with hydrochemical modeling were used in order to elucidate the sources and geochemical processes controlling nitrate contamination of shallow alluvial groundwater underneath a riverside agricultural field in the Buyeo area, Korea. Beneath vegetable fields in the sandy soil, the mean nitrate concentration of groundwater was 148.6 mg/L, which is significantly higher than in groundwater (mean 28.8 mg/L) beneath silty soils underneath rice paddy fields. Nitrogen isotope data indicate that synthetic fertilizers are the predominant source of groundwater nitrate in the study area. Denitrification during recharge through rice paddy soils appears to be responsible for the lower nitrate concentrations in groundwater beneath the silty soil zone. The relationship between nitrogen and oxygen isotope data of nitrate also suggests mixing of two different groundwater bodies with nitrates from the silt zone and the sand zone. Geochemical mass balance modeling on hydrochemical data indicates that various agricultural chemicals such as urea, lime, magnesium sulfate and potassium chloride dissolve in vegetable fields of the sandy zone, resulting in significant enrichment of various solutes such as K+, Ca2+, Mg2+, NO3-, SO42- and Cl-. As a consequence of over-utilization of synthetic nitrogen fertilizers, the sand zone is characterized by very high nitrate concentrations in the groundwater. This study suggests that a reduction of over-fertilization especially on vegetable fields in the riverside sand zone is required to minimize the nitrate contamination of groundwater. This study also shows that combination of geochemical and isotopic techniques with simple mass balance modeling provides information about the causes and processes of nitrate contamination of groundwater underneath a riverside agricultural field. The study also provides sustainable measures to optimize fertilization rate as an important basis of eco-friendly agriculture.
KW - Groundwater pollution
KW - Mass balance modeling
KW - Nitrate
KW - Nitrogen and oxygen isotopes
KW - Riverside alluvium aquifer
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U2 - 10.1016/j.agwat.2009.08.001
DO - 10.1016/j.agwat.2009.08.001
M3 - Article
AN - SCOPUS:70349166294
VL - 96
SP - 1819
EP - 1827
JO - Agricultural Water Management
JF - Agricultural Water Management
SN - 0378-3774
IS - 12
ER -