Combining dissolved organic matter correlation and water quality parameters to unravel the fate of organophosphate esters in Uliastai Lake

Environmental risk of organophosphate esters (OPEs) have garnered increasing attention as emerging contaminants in the global world. However, there is limited understanding regarding the concentration of OPEs and the impact of eutrophication lakes. Therefore, this study comprehensively examined the distribution characteristics of OPEs in water and sediments of Uliastai Lake, analysed their potential sources and pathways, explored the correlations between OPEs and dissolved organic matter (DOM) and water quality parameters, and conducted a risk assessment of OPEs. The study revealed that the average concentration of Σ₁₁OPEs in the water was 694.71 ng/L, and the Σ₁₂OPEs in the sediments was 105.99 ng/g (dw). OPEs primarily originated from domestic and tourism-related waste, boat and architectural coatings, wastewater treatment plants, industrial effluent discharge and transportation emissions. Triethyl phosphate (TEP) showed significant negative correlations with dissolved oxygen and turbidity (p < 0.05), whereas TEP, Tri (2-chloroethyl) phosphate (TCEP), Tri (2-chloroisopropyl) phosphate (TCPP) and alkyl-OPEs showed significant positive correlations with conductivity (p < 0.05). In addition, alkyl-OPEs exhibited a significant negative correlation with the fluorescence index of DOM and a significant positive correlation with the freshness index. The risk assessment results indicated that TEP and TECP have ecological risks and require strengthened management and control. This study comprehensively analysed the environmental behaviour of OPEs, providing new insights into the migration and transformation of emerging contaminants.