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 3 / 20 Many studies on ecological security evaluation employ methods such as hierarchical analysis [21], neural networks [22], and others. However, these methods often fail to accurately identify potentially toxic groups in target compounds. The ECOSAR program [23], a computer-based prediction tool, assesses the toxicity of substances to aquatic organisms by using Structure-Activity Relationships (SARs) to evaluate both acute (short-term) and chronic (long-term) toxicity to fish, aquatic invertebrates, and plants. Massarsky et al. critically evaluated ECOSAR for predicting per- and polyfluoroalkyl substances (PFAS) ecological risks, highlighting strengths and limitations across chemical classes [24]. The T.E.S.T. soft- ware [25] can process large datasets and accurately identify toxic groups within target compounds, enabling rapid toxicity assessments for chemicals with similar structures. Furthermore, it can comprehensively predict the toxicity of the target substances. Zhou et al. evaluated seven in silico tools—including ECOSAR and T.E.S.T.—against 37 Priority Controlled Chemicals and 92 New Chemicals in China for Daphnia and fish acute toxicity prediction [26]. RQ analysis [27] is a com- prehensive method used to evaluate pollutant exposure and hazard effects. Montuori et al. conducted a seasonal survey in the Sele River Estuary (Southern Italy), reporting that worst‐case RQ values for chlorpyrifos, pyrimiphos‐methyl, and

parathion exceeded 1.0, underscoring the need for targeted monitoring [28]. Currently, these three approaches are widely used to assess water quality safety. The combined use of ECOSAR, T.E.S.T., and RQ provides a more effective ecological safety assessment compared to traditional detection methods. To enable the assessment of the water quality characteristics, microbial diversity, and ecological security of the Lian- huan Lake, various analytical methods are employed. Chemical analysis methods are used to analyze the physical and chemical indicators, the TLI is used to assess the lake’s eutrophication, the WQI and IWQI are used to evaluate the water quality, high-throughput sequencing technology is utilized to analyze the biodiversity of the Lianhuan Lake, gas chroma- tography is employed to analyze organophosphorus in water and sediment, and ECOSAR, T.E.S.T, and RQ evaluation methods are adopted to assess the ecological safety of the Lianhuan Lake. It provides data support for the evaluation index system of organic phosphorus pollution in shallow lakes and the selection of evaluation methods, and to provide decision-making basis for maintaining the ecological stability of lakes and reservoirs. 2. Materials and methods 2.1 Materials The specimens are gathered at Lianhuan Lake in Daqing City, located in Heilongjiang Province (as shown in Fig 1). The sample location and sampling sites are shown in Table 1. All sampling sites are public waters managed by the Daqing

Water Conservancy and Ecology Bureau and do not require special sampling permits. This study did not involve protected species or private land. 2.2 Methodology for collecting water and sediment samples Water samples were obtained in June 2021 using an automated sampler (W2BC-9600, Henan Mu Xiang Experimental Equipment Co., Ltd.) in accordance with GB/T 14581−93. At each of the five sampling points, three replicate samples of 5 000 mL each were collected. Sediment samples were collected in June 2021 using a mud collector (CN-100, Guangzhou Ruibin Technology Co., Ltd.). At each location, three replicate grabs were taken, yielding 500 g of sediment per replicate. 2.3 Water quality analysis methodology 2.3.1 Method for analyzing physical and chemical indices. The water and sediment samples were analyzed for several physical and chemical parameters to determine the quality of water. These parameters include water temperature (WT), pH, total phosphorus (TP), total nitrogen (TN), dissolved oxygen (DO), permanganate index (CODMn), ammonia nitrogen (NH3-N), Secchi depth (SD), Chlorophyll-a (Chl-a) and nitrate nitrogen (NO3-N). All indicators are measured according to the national standard method GBT5750−2023.