Abstract：
Wastewater treatment plants (WWTPs) are essential for maintaining a good water quality of surface waters. However, WWTPs are also associated with water quality deterioration and hydro-morphological alteration. Riverine communities respond to these stressors with changes in their community structure, abundance and diversity. In this study, we used a dataset of 94 monitoring sites across North Rhine-Westphalia, Germany to investigate the influence of WWTPs on the water quality and hydro-morphological quality in river sections downstream of WWTP effluents. More specifically, we analyzed the effects of the percentage of WWTP effluents (in relation to median base flow) on four stressor groups (physico-chemistry, micropollutants, hydrological and morphological alteration) using Linear Mixed Models (LMM). Furthermore, we assessed the impact of a selection of twelve ecologically relevant stressor variables reflecting water quality deterioration and hydro-morphological alteration on reference fish communities using Canonical Correspondence Analysis (CCA). The percentage of WWTP effluents was correlated with water quality, especially with toxic units of a wide range of pharmaceuticals including diclofenac, venlafaxine and sulfamethoxazole (R² up to 0.54) as well as specific pesticides (e.g., terbutryn: R² = 0.33). The correlation of percent WWTP effluents with hydro-morphological alteration was weaker and most pronounced for the frequency of high flow (R² = 0.24) and flow variability (R² = 0.19). About 40 % of the variance in the fish community structure were explained by 12 stressor variables in the CCA models. Water quality and hydrological, but not morphological stressors showed strong albeit highly variable effects on individual fish species. The results indicate that water quality degradation and hydrological alteration are important factors determining the ecological status of fish communities. In this context, WWTP effluents can impose relevant point sources of pollution that affect water quality but also cause alterations of the hydrological regime. Further management measures addressing both stressor groups are needed to improve the ecological status.
摘要：
废水处理厂（WWTP）对于维持地表水的良好水质至关重要。然而,污水处理厂还与水质恶化和水文形态改变有关。河流社区通过社区结构的变化来应对这些压力源，丰富和多样性。在这项研究中,我们使用了北莱茵-威斯特法伦州94个监测点的数据集，德国将研究污水处理厂对污水处理厂下游河段水质和水文形态质量的影响。更具体地说,我们分析了污水处理厂流出物百分比(相对于中值基流)对四个应激源组的影响(物理化学，微污染物,水文和形态变化)使用线性混合模型(LMM)。此外，我们使用规范对应分析（CCA）评估了反映水质恶化和水文形态变化的十二个生态相关压力源变量对参考鱼类群落的影响。污水处理厂废水的百分比与水质相关，特别是包括双氯芬酸在内的各种药物的毒性单位，文拉法辛和磺胺甲恶唑（R²高达0.54）以及特定农药（例如，terbutryn：R²=0.33）。对于高流量（R²=0.24）和流量变异性（R²=0.19）的频率，污水处理厂流出物百分比与水文形态变化的相关性较弱，最明显。CCA模型中的12个应激源变量解释了鱼类群落结构中约40％的方差。水质和水文，但形态应激源对单个鱼类没有表现出强烈的影响，尽管变化很大。结果表明，水质退化和水文变化是决定鱼类群落生态状况的重要因素。在这种情况下，污水处理厂的废水可能会造成相关的点污染源，从而影响水质，但也会导致水文状况的改变。需要进一步的管理措施来解决这两个压力源群体，以改善生态状况。
