Data for: Effects of treated wastewater on the ecotoxicity of small streams – unravelling the contribution of chemicals causing effects

Wastewater treatment plant effluents are important point sources of micropollutants. To assess how the discharge of treated wastewater affects the ecotoxicity of small to medium-sized streams we collected water samples up- and downstream of 24 wastewater treatment plants across the Swiss Plateau and the Jura regions of Switzerland. We investigated estrogenicity, inhibition of algal photosynthetic activity (photosystem II, PSII) and growth, and acetylcholinesterase (AChE) inhibition. At four sites, we measured feeding activity of amphipods (<em>Gammarus fossarum</em>) <em>in situ</em> as well as water flea (<em>Ceriodaphnia dubia</em>) reproduction in water samples. Ecotoxicological endpoints were compared with results from analyses of general water quality parameters as well as a target screening of a wide range of organic micropollutants with a focus on pesticides and pharmaceuticals using liquid chromatography high-resolution tandem mass spectrometry. Measured ecotoxicological effects in stream water varied substantially among sites: 17β-estradiol equivalent concentrations (EEQ_bio, indicating the degree of estrogenicity) were relatively low and ranged from 0.04 to 0.85 ng/L, never exceeding a proposed effect-based trigger (EBT) value of 0.88 ng/L. Diuron equivalent (DEQ_bio) concentrations (indicating the degree of photosystem II inhibition in algae) ranged from 2.4 to 1576 ng/L and exceeded the EBT value (70 ng/L) in one third of the rivers studied, sometimes even upstream of the WWTP. Parathion equivalent (PtEQ_bio) concentrations (indicating the degree of AChE inhibition) reached relatively high values (37 to 1278 ng/L) mostly exceeding the corresponding EBT (196 ng/L PtEQ_bio). Decreased feeding activity by amphipods or waterflea reproduction compared to the upstream site was observed at one of four investigated sites only. Results of the combined algae assay (PSII inhibition) correlated best with results of chemical analysis for PSII inhibiting herbicides. Estrogenicity was partly and AChE inhibition strongly underestimated based on measured steroidal estrogens respectively organophosphate and carbamate insecticides. An impact of dissolved organic carbon on results of the AChE inhibition assay was obvious. For this assay more work is required to further explore the missing correlation of bioassay data with chemical analytical data. Overall, the discharge of WWTP effluent led to increased estrogenicity, PSII and AChE inhibition downstream, irrespective of upstream land use.污水处理厂（wastewater treatment plant, WWTP）出水是微污染物的重要点源。为评估经处理废水排放对中小型溪流生态毒性的影响，我们在瑞士高原与汝拉（Jura）地区的24座污水处理厂的上下游点位采集了水样。我们检测了雌激素活性、藻类光合活性（光系统II, PSII）与生长的抑制作用，以及乙酰胆碱酯酶（acetylcholinesterase, AChE）抑制活性。在4个采样点位，我们原位（in situ）检测了端足类动物（*Gammarus fossarum*）的摄食活性，并对水样中的水蚤（*Ceriodaphnia dubia*）繁殖情况进行了分析。我们将生态毒理学终点与常规水质参数分析结果，以及采用液相色谱高分辨串联质谱法针对农药和药物类有机微污染物的广谱靶向筛查结果进行了对比。 溪流水体中检测到的生态毒理学效应因采样点位差异显著：17β-雌二醇等效浓度（EEQ_bio，用于表征雌激素活性水平）相对较低，范围为0.04~0.85 ng/L，未超过提议的基于效应的触发值（effect-based trigger, EBT）0.88 ng/L。敌草隆等效浓度（DEQ_bio，用于表征藻类光系统II抑制程度）范围为2.4~1576 ng/L，在三分之一的研究河流中超过EBT值（70 ng/L），部分点位甚至位于污水处理厂上游。对硫磷等效浓度（PtEQ_bio，用于表征乙酰胆碱酯酶抑制程度）达到较高水平（37~1278 ng/L），多数超过对应EBT值（196 ng/L PtEQ_bio）。仅在4个调查点位中的1个，观察到端足类动物摄食活性较上游点位下降，或水蚤繁殖能力出现降低。 藻类联合检测（光系统II抑制）结果与光系统II抑制类除草剂的化学分析结果相关性最佳。基于检测到的甾体雌激素、有机磷与氨基甲酸酯类杀虫剂，雌激素活性被部分低估，而乙酰胆碱酯酶抑制活性则被显著低估。溶解有机碳对乙酰胆碱酯酶抑制检测的影响较为明显，该检测方法仍需开展更多研究以进一步探索生物检测数据与化学分析数据之间缺失的相关性。 总体而言，污水处理厂出水的排放导致下游水域的雌激素活性、光系统II抑制与乙酰胆碱酯酶抑制活性升高，且该效应不受上游土地利用类型的影响。