Integrating microbial community dynamics and emerging contaminants (ECs) for precisely quantifying the sources in groundwater affected by livestock farming.

Livestock farming is a major emission source of emerging contaminants (ECs); improper management of ECs could lead to severe groundwater pollution. However, research on accurately controlling the impact of large-scale livestock pollution in groundwater and quantifying sources of ECs pollution from livestock farming to formulating effective control measures is scarce. For the first time, the groundwater near four livestock farms (broiler, dairy, aquaculture, and pig farms) was selected as the research object to characterize the ECs, analyze the impact of ECs on microbial communities, and identify the pollution sources of livestock groundwater by the fast expectation-maximization of microbial source tracking (FEAST). Significant differences in the levels of antibiotics and hormones from four livestock farms led to changes in the groundwater microbial communities. The ECs improved the uniqueness of source biomarkers, providing better help for FEAST distinguishing livestock pollution sources at various groundwater mixing ratios. This study improved the accuracy of FEAST in investigating the pollution sources in groundwater and provided experimental evidence for accurate source tracking of ECs in groundwater in large-scale areas heavily polluted by livestock farming.