Study Of Water Quality Criteria On1,2,4-trichlorobenzene In China And Toxicity Of Typical Pollutants To Tetrahymena Thermophlie

Water quality criteria (WQC) which is the scientific basis for water quality standards development and environmental management reflects scientifically the ecological effects of pollutants. WQC provides theoretical basis for the establishment of water quality standard (WQS) and is used to administrate the utilization of different waters.1,2,4-trichlorobenzene (1,2,4-TCB) is one of the most widely used persistent organic pollutants, which is a more toxic compound. Takeing the organic contaminant1,2,4-TCB as an example, the toxicological database of1,2,4-TCB in China was establishes through the processes of literature research, species selection and quality screening. Their criteria values were derived by different derivation methods. The results are as following:The acute and chronic criteria values of1,2,4-TCB for protection of freshwater aquatic life by Species Sensitivity Distribution Method were185.79μg·L-1and22.34μg·L-1, respectively. While the acute and chronic criteria values of1,2,4-TCB for protection of freshwater aquatic life by Toxicity Percentile Rank Method were132.29μg·L-1and31,82μg·L-1. This research provides important information for the study of water quality standards for1,2,4-TCB in China.Using Tetrahymena thermophila as indication organism, the single acute toxicity of11kinds of typical contaminants and genotoxicity induced by2,4-dichlorophenol (2,4-DCP),2,3,4-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP) were determined. The48-hour EC50values to T. thermophila showed that the order of the toxicity was PCP>Hg2+> lindane>2,4,6-TCP>2,4-DCP>1,2,4-TCB> Cr6+> chlorpyrifos> Pb2+> nitrobenzene> ammonia. It showed that the effect of water hardness on the acute toxicities of the three CPs to T. thermophile had certain influence, but the impact was relatively insignificant. The results in the SCGE showed that there were significant differences (P<0.05) between the control and treatment groups at various concentrations of the three CPs. It recommended that the comet assay of T. thermophile is sensitive to the three detected CPs and could be a useful tool for screening and detecting of environmental genotoxins.