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 16 / 20 algae. Naled was highly toxic to fish and harmless to daphnid and green algae. Z-Tetrachlorvinphos was harmless to daphnid, fish and green algae. Prothiophos was highly toxic to daphnid and fish, toxic to green algae. Both Suprofos, Coumaphos and Prothiophos belonged to the class of organophosphate esters, which interfere with nervous system function by inhibiting acetylcholinesterase (AChE) activity. Since these compounds had similar toxic- ity mechanisms in aquatic organisms, they exhibited high toxicity to invertebrates such as Daphnia [48]. Therefore, the amount and frequency of use of organophosphorus pesticides should be reasonably controlled to protect the ecological safety of Lianhuan Lake. 3.6.3 T.E.S.T. The results of the evaluation of the BCF and the LC₅₀ in Lianhuan Lake (Table 8) showed that the BCF values for the organophosphorus compounds in all samples were less than 2000, indicating that these organophosphorus compounds had a relatively limited tendency to accumulate in organisms and a low risk of transmission through the food chain. None of the organophosphorus concentrations detected reached the lethal endpoint concentration when compared to the 96-hour LC₅₀ for fathead minnow automatically generated by the T.E.S.T. software. 3.6.4 RQ. The RQ assessment results (Table 9) showed that, in high ecological risk studies, Suprofos posed a high ecological risk to fish, daphnid, and green algae; Coumaphos posed a high ecological risk to daphnid; O,O,O-

Triethylphosphorothioate posed a high ecological risk to daphnid; mevinphos posed a high ecological risk to fish and green algae; and Prothiophos posed a high ecological risk to fish and daphnid. Suprofos was a highly toxic organophosphorus compound. Suprofos was harmful to humans in that it caused symptoms of poisoning such as headache, dizziness, nausea and vomiting. High doses or prolonged exposure may cause serious effects on the nervous system, liver and kidneys [49]. The danger of Mevinphos to the human body was manifested in its ability to inhibit cholinesterase activity. It caused dizziness, weakness, vomiting, excessive sweating, salivation, and in severe cases, muscle spasms, coma, respiratory distress, and pulmonary edema. Prothiophos was highly toxic to aquatic organisms and had long-lasting effects [50]. The study on moderate ecological risks found that Thionazin posed moderate ecological risks to daphnid; Ethoprophos posed moderate ecological risks to daphnid; EPN posed moderate ecological risks to fish, daphnid, and green algae; Coumaphos posed moderate ecological risks to fish and green algae; Naled posed moderate ecological risks to daphnid; and Prothiophos posed moderate ecological risks to green algae. Ethoprophos and Suprofos were detected in both N1 and N3, and although their concentrations were different, the ecological risk trends were the same. In summary, based on the results of the three evaluations of ECOSAR, T.E.S.T. and RQ, the organophosphorus com-

pounds detected in Lianhuan Lake—Suprofos, Coumaphos and Prothiophos—were highly toxic to daphnia, and Suprofos Table 8. BCF and LC50 prediction of organophosphorus components (mg/L). Samples No. Organophosphonic BCF LC50 (mg/L) Organophosphorus Concentration(μg/L) Over LC50 Yes or No N1 Thionazin 39.03 7.95 0.010 No Ethoprophos 33.49 0.95 0.013 No Suprofos 251.06 0.35 0.161 No EPN 378.27 2.46 0.246 No Coumaphos / 0.95 0.101 No N3 Ethoprophos 33.49 0.95 0.028 No Suprofos 251.06 0.35 0.075 No W4 O,O,O-Triethylphosphorothioate 7.57 35 0.008 No Mevinphos / 48.67 0.015 No Naled 5.90 4.19 0.021 No Z-Tetrachlorvinphos 598.54 0.17 0.043 No Prothiophos 354.29 0.0983 0.019 No Note:/ indicates that it is not queried in T.E.S.T https://doi.org/10.1371/journal.pone.0332712.t008