Assessing the impact of leather industry to water quality in the Aojing watershed in Zhejiang Province, China.

The development of the leather industry in the Aojiang watershed of Zhejiang province increased the release of waste water. In the waste water, ammonium nitrogen (NH(+) (4)-N) and germanium (Ge) are the main pollutants. In recent years, literature has documented that the intake of high concentrations of NH(+) (4)-N and Ge harms human health and biological species. This paper focuses on assessing the trends of NH(+) (4)-N and Ge concentrations in the released waste water in Aojiang watershed and on understanding their relationships with the released waste water using regression and correlation statistics. The paper also utilizes the integrated pollution index to evaluate the water quality in the watershed. Preliminary results show that, from 1992 to 1998, the concentrations of NH(+) (4)-N and total Ge increased 13 and 14 times, respectively, and they decreased somewhat after 1998. The concentrations of NH(+) (4)-N and total Ge are positively correlated to the amount of released waste water. These concentrations of NH(+) (4)-N and Ge, respectively, exceed 12 and 3 times, of the water standards. The water quality in the watershed degraded from Type III in 1992 to over Type V in 2003 when they were compared with the national water quality standards. It appeared that the pollution had positive correlation with leather industry production. The degraded water has no doubt affected human health and the ecosystem health. These results can provide scientific information for the local government to reasonably adjust the industry structure and reduce the pollution to protect the environment.