Department of Geography, McGill University, 805 Sherbrooke Street West, H3A 0B9, Montreal, Canada.
Department of Civil Engineering & Applied Mechanics, McGill University, 817 Sherbrooke Street West, H3A 0C3, Montreal, Canada.
Water Res. 2018 Nov 15;145:707-720. doi: 10.1016/j.watres.2018.08.053. Epub 2018 Aug 29.
The contamination of freshwater systems arises in many river basins due to industrialization and population growth, posing risks to ecosystems and human health. Despite these concerns, the fate and potential impact of many emerging pollutants are currently unknown, especially when the compounds are released into surface waters from populations distributed across large spatial scales. In order to address this shortcoming, a spatially-explicit contaminant fate model was developed as an extension of the global, vector-based river routing model HydroROUT. HydroROUT operates at very high spatial resolution (∼500 m), simulates river and stream chemical transport with in-stream removal, and contains links to a set of lakes and reservoirs, which act as a partial sink during the transport. The chemical fate model was applied to China and includes a consumption and release module based on county-level population demographics, considers point-source contributions from 2547 wastewater treatment plants, and accumulates contributions of rural and urban populations not connected to sewage treatment plants. As a case study, the sources and fates of the estrogens estrone (E), 17β-estradiol (E), estriol (E), as well as the synthetic estrogenic steroid hormone 17α-ethinylestradiol (EE) were modelled in Chinese surface water bodies. Preliminary validation of the results showed predictions to be within the ranges of concentrations reported in literature, with exception of EE. The total estrogenic mass in the entire river and lake system amounted to 370 tonnes of estrogens, with about 1.3 tonnes per year discharged to the ocean, neighboring countries or to inland sinks. Under a selected baseline scenario, eco-toxicological risk-i.e., contaminant concentrations in excess of the predicted no effect concentration (PNEC)-is found in 23.6% of all analyzed rivers of China with an average flow > 0.1 m/s. Out of these, about 4% of rivers showed a high level of risk of 10 times or more above PNEC. Medium-to-large rivers are disproportionally affected; for example, 23.6%, 37.3%, 29.0% and 21.6% of river length are at risk in rivers of 1-10, 10-100, 100-1,000, and 1,000-10,000 m/s of discharge, respectively, whereas no risk was predicted in the largest rivers (i.e., >10,000 m/s) of China. Wastewater treatment plants process 22.5% of the total hormone load and thus play an important role in water quality control by reducing the risk in substantial portions of the river network, which would otherwise show elevated risk. Releases from untreated population dominate by far the overall contribution to risk.
由于工业化和人口增长，许多河流流域的淡水系统受到污染，对生态系统和人类健康构成威胁。尽管存在这些担忧，但许多新兴污染物的命运和潜在影响目前尚不清楚，特别是当化合物从分布在大空间尺度上的人群释放到地表水中时。为了解决这一不足，我们开发了一种具有空间显式特征的污染物命运模型，作为基于全球矢量的河流路径模型 HydroROUT 的扩展。HydroROUT 以非常高的空间分辨率（约 500m）运行，模拟河流和溪流中的化学输送，并具有去除作用，其中包含了一组湖泊和水库的链接，这些湖泊和水库在输送过程中充当部分汇。化学命运模型应用于中国，包括一个基于县级人口统计数据的消耗和释放模块，考虑了 2547 个污水处理厂的点源贡献，并积累了未连接到污水处理厂的农村和城市人口的贡献。作为一个案例研究，在我国地表水体内模拟了雌激素雌酮（E）、17β-雌二醇（E）、雌三醇（E）以及合成雌激素类固醇激素 17α-乙炔雌二醇（EE）的来源和命运。结果的初步验证表明，预测值在文献报道的浓度范围内，除 EE 外。整个河流和湖泊系统中的总雌激素质量达到 370 吨，其中每年约有 1.3 吨排入海洋、邻国或内陆汇。在选定的基线情景下，生态毒性风险——即污染物浓度超过预测无影响浓度（PNEC）——在中国所有分析河流的 23.6%中发现，平均流量>0.1m/s。在这些河流中，约有 4%的河流显示出 PNEC 高出 10 倍或以上的高风险。大中河流受到不成比例的影响；例如，在 1-10、10-100、100-1、1000-1 和 1000-10000m/s 流量的河流中，风险分别为 23.6%、37.3%、29.0%和 21.6%，而在我国最大的河流（即>10000m/s）中则没有预测到风险。污水处理厂处理了 22.5%的总激素负荷，因此通过减少大部分河网的风险，在水质控制方面发挥了重要作用，否则这些河网的风险将会升高。未经处理的人群排放物仍然是造成风险的主要因素。
