RT Journal Article
SR Electronic
T1 A three-pronged approach for identifying source and extent of nitrate contamination in groundwater
JF Journal of Soil and Water Conservation
FD Soil and Water Conservation Society
SP 493
OP 503
DO 10.2489/jswc.73.5.493
VO 73
IS 5
A1 Ju, Y.
A1 Kaown, D.
A1 Lee, K.-K.
YR 2018
UL http://www.jswconline.org/content/73/5/493.abstract
AB A method to delineate the nitrate (NO3−) contamination of a study area by sequential and statistical use of dual isotope data, principal component analysis (PCA), and land use/land cover (LULC) data was demonstrated using data from Eumseong, Korea. First, a dual isotope approach was applied to identify the possible NO3− sources and quantify their contribution to NO3− contamination using Bayesian statistics. Second, a PCA was performed to discriminate and evaluate the impact of NO3− contamination on chemical evolution in the aquifer. Lastly, we incorporated the LULC data into a regression analysis to identify the contribution of various land uses to NO3− recharge. Some samples had NO3− and iron (Fe) concentrations above the local drinking water quality standard, and the distributions of potassium (K+), sulfate (SO42−), Fe, and manganese (Mn) were skewed significantly. Trends from the dual isotope analysis suggested three major sources of NO3− contamination. Among the three sources, Bayesian statistics indicated that the NO3− contamination was largely attributable to influx from manure/sewage and soil nitrogen (N). Based on the PCA, following screening for skewed data, a contamination indicator was extracted. The indicator exhibited positive correlations with NO3−, chlorine (Cl−), strontium (Sr2+), calcium (Ca2+), sodium (Na+), magnesium (Mg2+), K+, and SO42−, suggesting a single strong source. The regression analysis, using the LULC information, determined that agriculture activities in nonpaddy areas were responsible for the NO3− recharge. This study identified the benefits of combining dual isotope analysis, PCA, and LULC data for discriminating and evaluating sources of NO3− contamination when diverse contaminants are involved in geochemical evolution.