Water quality criteria (WQC) are threshold limits for pollutants or other hazard factors in the ambient water environment, which are based on scientific experiments and extrapolations. Until now, there is limited information available regarding the study of water quality criteria in China. It is imperative to launch national-level systematic WQC studies that focus on the regional characteristics of China and provide scientific support for the enactment or revision of water quality standards and environmental management. This article reviews the concept of WQC and discusses the methodology and global progress of WQC research. The article also summarizes the key scientific issues in WQC research, including species sensitivity distribution, toxicological endpoint selection, and models selection. Furthermore, we can adopt the derivation method used in the USA and divide WQC into acute and chronic criteria. Finally, considering the current status of WQC research in China, we point out important directions for future national studies, including the selection of native species and the comprehensive use of models.
FENG ChengLian WU FengChang ZHAO XiaoLi LI HuiXian CHANG Hong
In this study, toxicological data for zinc （Zn）, cadmium （Cd）, hexavalent chromium （Cr （VI））, benzene, and nitrobenzene were collected from various databases and publications, screened and then constructed into species sensitivity distribution （SSD） curves. Then water quality criteria （WQC） were derived for protection of the freshwater aquatic life in China against five representative pollutants. The values derived in this study were compared with those issued by the US Environmental Protection Agency and the Chinese national environmental standard for surface water to identify factors underlying the differences. The results showed that the SSD curves for the five pollutants differed significantly, with the examined aquatic species being gen- erally more sensitive to Zn, Cd, and Cr （VI） than benzene and nitrobenzene. The acute WQC were： 48.43 μg L-1 for Zn, 0.4218 μg L-1 for Cd, 45.79μg L-1 for Cr （VI）, 2651 μg L-1 for benzene, and 1426 μg L-1 for nitrobenzene. The chronic WQC were： 20.01μg L-1 for Zn, 0.2428 μg L-j for Cd, 14.22 μg L-1 for Cr （VI）, 530.2 μg L J for benzene, and 286.2 μg L-1 for nitroben- zene. The results of this comparative study of representative pollutants may offer guideline values for future WQC studies for China.
