Abstract
Shanghai is experiencing drinking water supply problems that are caused by heavy pollution of its raw water supply, deficiencies in its treatment processes, and water quality deterioration in the distribution system. However, little attention has been paid these problems of water quality in raw water, water treatment, and household drinking water. Based on water quality data from 1979 to 2016, we show that microbes (TBC), eutrophication (TP, TN, and NH3–N), heavy metals (Fe, Mn, and Hg), and organic contamination (chemical oxygen demand (COD), detergent (Linear Alklybenzene Sulfonate, LAS), and volatile phenols (VP)) pollute the raw water sources of the Huangpu River and the Changjiang (Yangtze River) estuary. The average concentrations of these contaminants in the Huangpu River are almost double that of the Changjiang estuary, forcing a rapid shift to the Changjiang estuary for raw water. In spite of filtering and treatment, TN, NH3–N, Fe, COD, and chlorine maxima of the treated water and drinking water still exceed the Chinese National Standard. We determine that the relevant threats from the water source to household water in Shanghai are: (1) eutrophication arising from highly concentrated TN, TP, COD, and algal density in the raw water; (2) increasing salinity in the river estuary, especially at the Qingcaosha Reservoir (currently the major freshwater source for Shanghai); (3) more than 50% of organic constituents and by-products remain in treated water; and, (4) bacteria and turbidity increase in the course of water delivery to users. The analysis presents a holistic assessment of the water quality threats to metropolitan Shanghai in relation to the city’s rapid development.
Highlights
There is no substitute for freshwater and it plays an essential role in sustaining societies and supporting and enriching the culture [1,2]
In China, the quality of surface freshwater is assessed based on 29 contaminants and is classified in five grades (I–V): grades I–III are suitable to be treated for drinking water, IV can be used by industry, and V is only suitable for agricultural or environmental use [6]
After water has been delivered to households, some contaminants, such as TBC, NH3 –N, Fe, chemical oxygen demand (COD), and turbidity have increased in concentration (Figure 2B,C)
Summary
There is no substitute for freshwater and it plays an essential role in sustaining societies and supporting and enriching the culture [1,2]. Pollution from domestic, industrial, and agricultural activities has led to the deterioration of water quality and exacerbated the problems of the availability of good quality water, especially in downstream coastal urban areas and in water-scarce areas [3,4]. Different countries or regions, depending on the purpose for which it are used, such as domestic consumption, industrial use, and environmental systems, usually categorize water contamination [5]. In China, the quality of surface freshwater is assessed based on 29 contaminants and is classified in five grades (I–V): grades I–III are suitable to be treated for drinking water, IV can be used by industry, and V is only suitable for agricultural or environmental use [6]. Water that fails to reach even the quality required for category V is classed as not being suitable for any functional use.
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