Quantifying the vulnerability of karst groundwater to emerging organic compounds in southwest China

Water resource security and sustainability of karst aquifers have been greatly concerned due to their significant contributions to domestic drinking and irrigation purposes since the Anthropocene. Yet, the assessment of karst groundwater vulnerability to emerging organic compounds (EOCs) sourced from anthropogenic activities was rather scanty. Here, we conducted a full-spectrum screening of 50 physiochemical indices and 50 EOCs, further providing a quantitative framework to accurate evaluation of karst aquifer vulnerability to EOCs based on large-scale sampling campaign of 440 monitoring wells in the Yunnan-Guizhou Plateau during 2019. As results, naphthalene (Nap, 82.27 %), atrazine (ATZ, 64.09 %), glyphosate (GLY, 41.59 %), and dioctyl phthalate (DOP, 33.41 %) were more frequently detected in groundwater. Obvious spatial heterogeneity of EOCs distribution was found among different types of aquifers. Specifically, higher contents of pesticides were observed in karst aquifers than in pore and fissure water, which suggesting the prominent sensitivity to anthropogenic stressors from EOCs. Furthermore, we quantified the contributions of dominant human activities (e.g., 23.65 % for agricultural activities, 10.89 % for daily life, and 11.58 % for industrial production) to the variations in aquifer. We revealed significant effects of agricultural activities on the hydro-chemical evolution and resource safety of karst groundwater based on the combine of aquifer hydrogeological characteristics and EOCs source analysis. The results highlight the importance of low impact agricultural development and reduced pesticides usage to karst groundwater resource protection. Our study provides new framework for aquifer vulnerability assessment to EOCs in karst aquifers and was helpful to groundwater pollution controlling and drinking water safety.