Delineating the impacts of poultry burial leachate on shallow groundwater in a reclaimed agro-livestock farming area, using multivariate statistical analysis of hydrochemical data

Burial is applied to dispose of livestock carcasses due to its convenience and cost efficiency despite concerns about groundwater contamination by leachate from burial pits. In particular, the burial method has caused debates about groundwater contamination sources around on-farm livestock burial sites because of pre- and coexisting contamination from livestock production and agriculture. To assess the causes of groundwater contamination around poultry burial pits that were constructed after an outbreak of avian influenza in 2010–11 in Korea, hydrochemical data of groundwater samples from monitoring wells (MWs, n = 14) and household wells (HWs, n = 30) were monitored to differentiate contamination sources. Hydrochemical data indicated that groundwater from MWs is characterized by higher enrichments of inorganic constituents including electrical conductivity (EC), NH₄, Ca, Mg, K, SO₄, HCO₃, Fe_(Total), and Mn_(Total), but lower concentrations of DO than groundwater from HWs. The combined use of the principal component analysis (PCA) and K-means cluster analysis (KCA) indicated that groundwater in seven MWs was affected by leachate. The parameters such as NH₄, Ca, Mg, K, SO₄, HCO₃, Fe_(Total), and Mn_(Total) are expected to be useful to identify the impact of leachate on groundwater in agricultural areas. This study suggests that (1) regional hydrochemical characteristics should be assessed to distinguish the effect of livestock burial leachate from other contamination sources and (2) the combined use of PCA and KCA is effective to identify the weakened impact of leachate leakage among overlapping multiple sources and processes of groundwater contamination.