Analysis of bacterial biodiversity and ecological risk evaluation of organophosphorus in Lianhuan Lake

PLOS One | https://doi.org/10.1371/journal.pone.0332712 September 26, 2025 17 / 20 and Prothiophos were highly toxic to fish, but at concentrations below the LC₅₀ for fish. Suprofos, mevinphos and Prothio- phos had high ecological risk. In order to reduce the harm of organophosphorus pesticides to water ecology, it is recom- mended to apply organophosphorus pesticides scientifically, encourage the use of biopesticides, avoid overdose, and reduce residues. 4. Conclusions Shallow lakes are ecologically important for maintaining biodiversity, regulating hydrological processes, purifying water, and supporting ecosystem services. This study selected Lianhuan Lake—a typical submersible lake in northern China—as the research subject. We analyzed its water‐quality characteristics, examined bacterial diversity in the water column and sediments, assessed organophosphorus pesticide pollution, and evaluated ecological safety. The results showed that the lake’s water quality meets Class V standards (GB 3838−2002), indicating only mild eutrophication (TLI) and minor contamination (WQI, IWQI). Across water and sediment samples, we identified 59 phyla, 180 classes, 407 orders, 520 families, and 1 062 genera, with diversity consistently higher in sediments. Water‐quality indicators influenced bacterial diversity in the order pH > TP > DO > TN > NH₃-N > NO₂-N > WT. Gas‐chromatography detected ten organophosphorus compounds in samples N1, N3, and W4: thionazin, ethoprophos, suprofos, EPN and coumaphos (N1); ethoprophos

and suprofos (N3); and O,O,O-triethylphosphorothioate, mevinphos, naled, Z-tetrachlorvinphos and prothiophos (W4). ECOSAR results indicated that nine compounds exhibited varying degrees of acute and chronic toxicity to fish, Daph- nia, and algae, with suprofos, coumaphos, and prothiophos highly toxic to Daphnia and suprofos and prothiophos highly toxic to fish (though at concentrations below the fish LC₅₀). T.E.S.T. predictions showed that neither BCF nor LC₅₀ values exceeded regulatory thresholds, while RQ assessment identified suprofos, mevinphos, and prothiophos as high ecolog- ical‐risk compounds. This work delivers the first integrated baseline assessment of Lianhuan Lake’s physicochemical status, microbial community structure, and organophosphorus pesticide–derived ecological risks, providing critical data and targeted recommendations for its sustainable management and conservation. Acknowledgments We thank the Heilongjiang University and State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology for providing the test platform. Table 9. RQ calculations for organophosphorus components. Samples NO. Organic Phosphonic RQ Fish Daphnid Green Algae N1 Thionazin 0.001 0.4 0.001 Ethoprophos 0.013 0.174 0.001 Suprofos 31.01 293.2 1.771 EPN 0.378 0.511 0.23 Coumaphos 0.739 177.6 0.236 N3 Ethoprophos 0.029 0.381 0.002 Suprofos 14.42 136.3 0.824 W4 O,O,O-Triethylphosphorothioate 0.002 1.19 0.002 Mevinphos 13.89 0 2.369 Naled 0.005 0.175 0 Z-Tetrachlorvinphos 0.007 0.007 0.003

Prothiophos 10.41 44.64 0.694 https://doi.org/10.1371/journal.pone.0332712.t009