SUN Lin-hua, FU Jin-mu

 (Institute of Geochemistry and Engineering, Suzhou College, Anhui, Suzhou234000, China)

 Abstract: Determination of the environmental background value of a heavily polluted river is difficult because it has undergone multi contributions from anthropogenic activities. In this study, normal probability plot and iterative 2 sigma technique have been applied to the NH₄⁺-N concentrations in Kuihe River water, Suzhou, for revealing their multi sources and determination of the environmental background value. The results indicate that NH₄⁺-N in the river water  originated from natural, agricultural, industrial and domestic sources and the environmental background value was 0.52-1.08 mg/L. In comparison with analysis of the data from other rivers in the area, the histogram and normal probability plot are considered to be useful for multi-source identification of pollution and determination of environmental background value. However, most of the samples without pollution should be guaranteed if the iterative 2 sigma technique is applied to environmental background study.

Key words: water pollution; environmental baseline; environmental background value; ammonia nitrogen; Kuihe River