Assessment of the impact of landfills on groundwater quality in Eastern China: a comprehensive analysis of inorganic solutes.

Groundwater contamination from non-engineered landfills has been extensively documented. However, there is a gap in extensive field research regarding whether engineered landfills can also contribute to groundwater contamination. We selected 62 engineered municipal landfills in Eastern China and collected both leachate samples from the landfills and groundwater samples from nearby wells. Through the analysis of inorganic solute indicators in both groundwater and leachate samples, we explored the impact of landfill leachate on the inorganic solute composition of groundwater. Our findings revealed that over half of the groundwater samples surrounding the landfill sites exceeded recommended drinking water limits for inorganic solutes. The correlation analysis demonstrates a significant relationship between Cl⁻, SO₄²⁻, Na⁺, and K⁺ levels in leachate and groundwater, highlighting the direct impact of landfill activities on groundwater quality. Moreover, specific characteristics of the landfill, such as its age, the total waste volume, and geographic location, were found to influence the inorganic solute composition in the groundwater. This effect was apparent in the positive correlations between the age of the landfill and NH₃-N, Ca²⁺, and Mg²⁺ levels in groundwater, the total waste volume of the landfill and Ca²⁺ content in groundwater, and the latitude of the landfill and Cl⁻ and HCO₃⁻ concentrations in groundwater. This work carries implications for assessing environmental risks associated with engineered landfills and enhancing landfill design, management, and monitoring practices. [ABSTRACT FROM AUTHOR]