For millions of people worldwide, sewage-polluted surface waters threaten water security, food security and human health. Yet the extent of the problem and its causes are poorly understood. Given rapid widespread global urbanisation, the impact of urban versus rural populations is particularly important but unknown. Exploiting previously unpublished archival data for the Ganga (Ganges) catchment, we find a strong non-linear relationship between upstream population density and microbial pollution, and predict that these river systems would fail faecal coliform standards for irrigation waters available to 79% of the catchment’s 500 million inhabitants. Overall, this work shows that microbial pollution is conditioned by the continental-scale network structure of rivers, compounded by the location of cities whose growing populations contribute c. 100 times more microbial pollutants per capita than their rural counterparts.

中文翻译：

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恒河集水区微生物污染的人口密度控制

对于全球数百万人而言，被污水污染的地表水威胁着水安全，粮食安全和人类健康。然而，问题的严重程度及其原因却鲜为人知。鉴于全球城市化进程迅速发展，城市人口与农村人口的影响尤为重要，但未知。利用先前未发布的恒河流域档案数据，我们发现上游人口密度与微生物污染之间存在很强的非线性关系，并预测这些河流系统将无法满足79％的流域粪便大肠菌标准的灌溉用水。 5亿居民。总的来说，这项工作表明，微生物污染取决于河流的大陆规模网络结构，再加上人口不断增长的城市所处的位置c。