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Environment and health
In China, serious pollution occurs widely in every river system and no single river is clean. More than half of the groundwater resources have been severely contaminated. According to FAO, 80 percent of the 50 000 km of major rivers in China are so degraded that they no longer support fish. Around urban areas 90 percent of rivers are seriously polluted, especially in the north where heavy industry is concentrated. Looking at their total river length, 69 percent of the Hai river, 73 percent of the Huai river and 71 percent of the Huang river are classified as polluted by Chinese standards (Burke, 2000).
In 2004, of all 745 monitored river sections, 28 percent were unsafe for any use and only 32 percent were safe for industrial and irrigation uses only. Of the 27 major monitored lakes and reservoirs, 48 percent were unsafe for any use, 23 percent were safe for industrial and irrigation uses only, and only 29 percent were safe for human consumption after treatment (World Bank, 2009a).
The extent of pollution aggravates water scarcity. Currently, approximately 25 km3 of polluted water are held back from consumption, contributing to unmet demand and groundwater depletion. As much as 47 km3 of water that does not meet quality standards are however supplied to households, industry, and agriculture, with the attendant costs related to damage. A further 24 km3 of water beyond rechargeable quantities are extracted from the ground, which results in groundwater depletion (World Bank, 2009a).
There are a number of complex factors behind this pollution crisis. The fundamental one is that economic growth is the number one goal of the country. Also, there has been a long period of ignorance and neglect at all government levels and lack of effective policy mechanisms to address those issues. Much of the pollution results from inadequate treatment of municipal and industrial wastewater (Burke, 2000).
Total wastewater discharges have steadily risen to 53 700 million tonnes in 2006 of which only 56 percent had some form of treatment (this rate reflects the installed wastewater treatment capacity rather than the actual treatment, which is likely to be lower because of the lack of sewage networks and funds for operation and maintenance in many cities). Since 2000, domestic wastewater discharges have surpassed industrial discharges, and have become the most important source of pollution. It was not until 2007 that the rising trend of water pollution began to show a sign of reverse, as total emissions of chemical oxygen demand (COD) dropped by 3.14 percent over the 2006 level. However, the water pollution situation is still very serious. A major element is that only 56 percent of municipal sewage receives some form of treatment, versus 92 percent of industrial discharges (World Bank, 2009a).The most challenging drinking water pollutant is fecal coliform from sewage.
Rural areas have also witnessed an increase in pollution caused by the inappropriate use of chemical pesticides and fertilizers: several groundwater sites were examined in northern China where nitrate levels exceeded the limits allowed for drinking water. Further, farmers have traditionally used sewage to irrigate crops but now they are also using industrial wastewater laced with all sorts of toxic and persistent chemicals (Burke, 2000).
The World Bank estimates that the water crisis is already costing China about 2.3 percent of the GDP, of which 1.3 percent is attributable to the scarcity of water, and 1 percent to the direct impacts of water pollution. These estimates do not include the cost of impacts for which estimates are unavailable, such as the ecological impacts associated with eutrophication and the drying up of lakes, wetlands, and rivers, and the amenity loss from the extensive pollution in most of China’s water bodies. Thus, total costs are undoubtedly higher.
The economic cost of disease and premature deaths associated with the excessive incidence of diarrhoea and cancer in rural China has been estimated, based on 2003 data, at 66 200 million Yuan, or 0.49 percent of the GDP (World Bank, 2009a). Above the Huang river, for example, abnormally high rates of mental retardation, stunting, and development diseases have been linked to naturally present arsenic and lead in water. In Shanxi province around the Huang river, high levels of lead and chromium were found in rice, and cadmium in cabbages (Burke, 2000).
In 2005, the area subject to waterlogging was 21.3 million ha. In northern China in particular, waterlogging, salinization and alkalization have been the main constraints to agricultural production. In 2005, 6.03 million ha of saline-alkaline cultivated areas have been improved or reclaimed and the total cultivated area protected from floods is about 44.1 million ha (MWR, 2006). More than 100 million ha of China’s land has become salinized over the past several decades. The area salinized by irrigation was an estimated 6.7 million ha in 1999 (Mashali, 2005). The majority of the most serious problems have occurred in the northeast, the northwest and in some places on the north China plain. In recent years, the area affected by salinization has somewhat fallen. Ironically, it may be that the same forces diverting surface water away from agriculture and forcing producers to rely increasingly on groundwater may be the primary cause of such improvements (Wang et al., 2005).
The depletion of groundwater resources is contributing to the drying up of lakes and wetlands and an increase in groundwater salinity, which occurs when seawater intrudes or when declining groundwater resources are substituted by brackish water that often lies between the shallow and deep groundwater tables. In some locations, intrusion of brackish water has been monitored at a rate of 0.5 to 2 mper year for the past 20 years. Sea water intrusion has occurred in 72 locations along coastal provinces, covering an area of 142 km2 (World Bank 2009a).