Occurrence and spatio-seasonal distribution of organophosphate tri- and di-esters in surface water from Dongting Lake and their potential biological risk

In this study, 24 surface water samples were collected from Dongting Lake, China, in the wet and dry seasons, then the concentrations, composition profiles and spatio-seasonal variations of nine organophosphate triesters (OPEs) and five organophosphate diesters (Di-OPs) were determined. Significantly higher total OPE concentrations (Sigma OPEs) were observed in the wet season (49.5-148 ng L-1) than in the dry season (5.00-45.7 ng L-1) suggesting higher input via tributaries discharge as well as wet deposition in the studied region. Whereas lower levels of TnBP and (triphenyl phosphate (TPHP) in wet season reflected their possible degradation under solar irradiation. Comparable levels of total Di-OPs (Sigma Di-OPs) were found in the wet season (3.41-13.9 ng L-1) and dry season (1.01-12.3 ng L-1). Tri(2-chloroethyl) phosphate and tris(2-chloroisopropyl) phosphate were the main OPE components, while diphenyl phosphate, di-n-butyl phosphate and bis(1,3-dichloro-2-propyl) phosphate were the main Di-OP components. High levels of OPEs and Di-OPs were found in Datong Lake suggesting possible local emissions potentially related to fishery activity in the land-locked lake. Samples at river mouths to the lake also have higher levels of target OPEs and Di-OPs, the results disclosed obvious discharges from tributaries in Hunan Province. Negligible non-carcinogenic and carcinogenic risks were determined based on the measured concentrations in source waters. A limited ecological risk aquatic organisms in the Dongting Lake was identified, with most risk from TPHP. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study revealed higher concentrations of OPEs in the wet season compared to the dry season in Dongting Lake, likely due to input from tributaries discharge and wet deposition. Lower levels of TnBP and TPHP in the wet season suggest degradation under solar irradiation. Tri(2-chloroethyl) phosphate and diphenyl phosphate were identified as main components of OPEs and Di-OPs, respectively.