Seasonal dynamics and typology of microplastic pollution in Huixian karst wetland groundwater: Implications for ecosystem health

This study offers an insightful and detailed examination of microplastic pollution in the Huixian karst wetland's groundwater, providing novel insights into the complex interplay of microplastic characteristics and their seasonal dynamics. We meticulously quantified microplastic concentrations, observing significant seasonal variation with values ranging from 4.9 to 13.4 n·L−1 in the wet season and 0.53–49.4 n·L−1 in the dry season. Our analysis pinpoints human activities and atmospheric deposition as key contributors to this contamination. A critical finding of our research is the pronounced disparity in microplastic levels between open wells and covered artesian wells, highlighting the vulnerability of open wells to higher pollution levels. Through correlation analysis, we unearthed the crucial influence of the karst region's unique hydrogeological characteristics on microplastic migration, distinctively different from non-karst areas. The karst terrain, characterized by its caves and subterranean rivers, facilitates the downward movement of microplastics from surface to groundwater, exacerbating pollution levels. Our investigation identifies agricultural runoff and domestic wastewater as primary pollution sources. These findings not only underscore the urgent need for environmental stewardship in karst regions but also provide a crucial foundation for formulating effective strategies to mitigate microplastic pollution in karst groundwater. The implications of this study extend beyond the Huixian karst wetland, offering a template for addressing microplastic pollution in similar ecosystems globally. [Display omitted] •Provides detailed analysis of microplastic types and properties in the groundwater environment of a karst wetland protection area.•Uncovers distinct seasonal patterns in microplastic concentrations in karst underground waters.•Reveals a close link between surface and underground water microplastics in karst ecosystems.•Highlights the need for targeted strategies to mitigate microplastic pollution's environmental and health impacts.•Local residents may be exposed to 27 microplastic particles daily via drinking water.