The Ganga River is facing mounting environmental pressures due to rapidly increasing human population, urbanisation, industrialisation and agricultural intensification, resulting in worsening water quality, ecological status and impacts on human health. A combined inorganic chemical, algal and bacterial survey (using flow cytometry and 16S rRNA gene sequencing) along the upper and middle Ganga (from the Himalayan foothills to Kanpur) was conducted under pre-monsoon conditions. The upper Ganga had total phosphorus (TP) and total dissolved nitrogen concentrations of less than 100 μg l⁻¹ and 1.0 mg l⁻¹, but water quality declined at Kannauj (TP = 420 μg l⁻¹) due to major nutrient pollution inputs from human-impacted tributaries (principally the Ramganga and Kali Rivers). The phosphorus and nitrogen loads in these two tributaries and the Yamuna were dominated by soluble reactive phosphorus and ammonium, with high bacterial loads and large numbers of taxa indicative of pathogen and faecal organisms, strongly suggesting sewage pollution sources. The high nutrient concentrations, low flows, warm water and high solar radiation resulted in major algal blooms in the Kali and Ramganga, which greatly impacted the Ganga. Microbial communities were dominated by members of the Phylum Proteobacteria, Bacteriodetes and Cyanobacteria, with communities showing a clear upstream to downstream transition in community composition. To improve the water quality of the middle Ganga, and decrease ecological and human health risks, future mitigation must reduce urban wastewater inputs in the urbanised tributaries of the Ramganga, Kali and Yamuna Rivers.

中文翻译：

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印度甘加河上游的营养和微生物水质量：污染源识别。

由于人口的快速增长，城市化，工业化和农业集约化，恒河正面临日益严峻的环境压力，导致水质恶化，生态状况恶化并对人类健康产生影响。在季风前的条件下，沿着恒河上部和中部（从喜马拉雅山麓到坎普尔）进行了无机化学，藻类和细菌的综合调查（使用流式细胞仪和16S rRNA基因测序）。上部恒河的总磷（TP）和总溶解氮浓度分别小于100μgl ^-1和1.0 mg l ^-1，但Kannauj的水质下降（TP = 420μgl ^-1）是由于受到人类影响的支流（主要是Ramganga和Kali河）的主要养分污染输入。这两个支流和亚穆纳河的磷和氮负荷以可溶性反应性磷和铵为主，细菌负荷高，指示病原体和粪便生物的分类单元数量大，强烈暗示了污水的污染源。高养分浓度，低流量，温水和高太阳辐射导致了卡利和拉姆甘加的主要藻华，这极大地影响了恒河。微生物群落中，杆菌属，噬菌体和蓝细菌占主导地位，群落在群落组成上显示出从上游到下游的明显过渡。为了改善恒河中部的水质，