Chemical evaluation of potable water in Eastern Qinghai Province, China: human health aspects.

Electric conductivity, pH, COD(Mn), nutrient concentration, chloride and sulfate concentrations, total dissolved sodium, potassium, calcium, magnesium, manganese, iron, cadmium, copper, arsenic, nickel, zinc, chromium and lead were evaluated to clarify concerns about the quality and safety of water used for drinking purposes in Qinghai Province, China. For this purpose, 12 water samples were collected from different villages, Qinghai (Koko Nor) Lake and medicinal springs close to the Town of Pingang during a study visit to China in 2003. The results showed that National Chinese and WHO drinking water standards were exceeded for nutrient concentration (3.2 mg l(-1) of TOT-N and 0.2 mg l(-1) of TOT-P) from Qinghai Lake. The presence of elevated electric conductivity (550 mS m(-1)) in mineral water resort samples should be a matter of a public concern. Also, samples from medicinal springs showed high concentrations of Fe (up to 1.9 mg l(-1)), As (up to 0.1 mg l(-1)) and Ni (0.05 mg l(-1)), which may be detrimental for human health if the water is consumed on a daily basis. The concentrations of Cu, Cd, Cr and Pb did not exceed the National Chinese and WHO drinking water standards, and therefore, water from the sampling area does not pose any significant threat to the consumers' health regarding these metals.