Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland; Institute of Civil, Environmental and Geomatic Engineering, ETH Zürich, 8093, Zurich, Switzerland.
Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland.
Water Res. 2016 Nov 1;104:547-557. doi: 10.1016/j.watres.2016.08.003. Epub 2016 Aug 3.
Wet-weather discharges contribute to anthropogenic micropollutant loads entering the aquatic environment. Thousands of wet-weather discharges exist in Swiss sewer systems, and we do not have the capacity to monitor them all. We consequently propose a model-based approach designed to identify critical discharge points in order to support effective monitoring. We applied a dynamic substance flow model to four substances representing different entry routes: indoor (Triclosan, Mecoprop, Copper) as well as rainfall-mobilized (Glyphosate, Mecoprop, Copper) inputs. The accumulation on different urban land-use surfaces in dry weather and subsequent substance-specific wash-off is taken into account. For evaluation, we use a conservative screening approach to detect critical discharge points. This approach considers only local dilution generated onsite from natural, unpolluted areas, i.e. excluding upstream dilution. Despite our conservative assumptions, we find that the environmental quality standards for Glyphosate and Mecoprop are not exceeded during any 10-min time interval over a representative one-year simulation period for all 2500 Swiss municipalities. In contrast, the environmental quality standard is exceeded during at least 20% of the discharge time at 83% of all modelled discharge points for Copper and at 71% for Triclosan. For Copper, this corresponds to a total median duration of approximately 19 days per year. For Triclosan, discharged only via combined sewer overflows, this means a median duration of approximately 10 days per year. In general, stormwater outlets contribute more to the calculated effect than combined sewer overflows for rainfall-mobilized substances. We further evaluate the Urban Index (A/A) as a proxy for critical discharge points: catchments where Triclosan and Copper exceed the corresponding environmental quality standard often have an Urban Index >0.03. A dynamic substance flow analysis allows us to identify the most critical discharge points to be prioritized for more detailed analyses and monitoring. This forms a basis for the efficient mitigation of pollution.
雨天排放物会导致人为微污染物负荷进入水生环境。瑞士的下水道系统中存在数千个雨天排放口，我们没有能力对其全部进行监测。因此，我们提出了一种基于模型的方法，旨在确定关键排放点，以支持有效的监测。我们应用了一个动态物质流模型来模拟四种不同进入途径的物质：室内（三氯生、草甘膦、铜）以及雨水引发的（草甘膦、草甘膦、铜）输入。考虑了在干燥天气下不同城市土地利用表面的积累以及随后的特定物质冲刷。为了评估，我们使用保守的筛选方法来检测关键排放点。这种方法仅考虑了从自然、未污染区域现场产生的局部稀释，即不包括上游稀释。尽管我们的假设很保守，但我们发现，在代表一年的代表性模拟期间，对于所有 2500 个瑞士市镇，草甘膦和草甘膦的环境质量标准在任何 10 分钟时间间隔内都不会超过。相比之下，在所有模拟排放点的 83%中，铜的环境质量标准在至少 20%的排放时间内超过，而三氯生的环境质量标准在 71%的排放时间内超过。对于铜，这相当于每年大约 19 天的总中位数持续时间。对于仅通过合流制溢流排放的三氯生，这意味着每年大约 10 天的中位数持续时间。一般来说，对于雨水引发的物质，雨水出口比合流制溢流对计算出的影响贡献更大。我们进一步评估城市指数（A/A）作为关键排放点的代理：三氯生和铜超过相应环境质量标准的集水区通常具有大于 0.03 的城市指数。动态物质流分析使我们能够识别最关键的排放点，以便对其进行更详细的分析和监测。这为污染的有效缓解奠定了基础。
