The Toxicity Characteristics Of Textile Effluent And River Water From Typical Areas In The Liao River Basin

Aquatic environments are often contaminated by wastewater from industrial, domestic, and agricultural sources. Water is a kind of important natural resources, and the first element of biological survival, the pollution will inevitably have a negative impact on humans and other organisms. While, the state enacted a series of sewage discharge standards and set up many sewage treatment plants, the physical and chemical indexes of water quality are expected to be predominantly in environmental standards of China. Sewage composition was very complex, the existing water pollution indicators cannot analysis the synergistic or antagonistic effect of complicated toxic compounds existed in sewage, as well as toxic effects on the aquatic organisms and environment, the influence of ecological balance and potential hazards to human health. The aquatic organism toxicity tests can better reflect the toxic effects of the known and unknown pollutants in aquatic environment, and contribute to a comprehensive evaluation of the biological toxic effects of contaminated wastewater.Textile industries are important sources of toxic discharges, while little attention was paid to the toxicity of textile effluents for discharge regulation. Zebrafish as a bioindicator was chosen to assess the detrimental effects of the wastewater samples collected from different stages of the textile industry and sewage treatment plants (STPs), including acute toxicity, DNA damage and lipid per-oxidation. The results show as follows:The wastewater samples from bleaching, rinsing and soaping of the textile industry exhibited high acute toxicity and genotoxicity. The coexisting components of dye compounds, as assistants and oxidants, seemed to cause some effect on the toxic response. After the treatment employing anoxic-oxic (A/O) process in STPs, the color and the chemical oxygen demand (COD) were reduced by40%and84%, respectively, falling within the criteria of Chinese Sewage Discharge Standard. In contrast, increases in acute toxicity and genotoxicity were observed in the anaerobic tank, indicating the formation of toxic intermediates. The genotoxicity of the effluent of the STP was not significantly different from that of the influent, suggesting the wastewater treatment processes were not effective to remove the genotoxicity of the dye wastewater. Results indicate that the effluent contains pro-oxidants since the activities of the glutathione (GSH), malondialdehyde (MDA), and total anti-oxidation capacity (T-AOC) were all elevated. Besides, decreases in superoxide dismutase (SOD) and glutathione-S transferase (GST) activities observed can be interpreted as a cytotoxicity sign due to an over-production of reactive oxygen species (ROS). Results of the present study suggest that the STPs were not capable of reducing the toxicity of wastewater sufficiently. Further treatment is needed to remove the potential risks posed by textile effluent to the ecosystems and human health, and employing toxicity index is necessary for discharge regulation.The comprehensive toxicity of water from five typical areas in the Liao River Basin was assessed. The results showed that all the water had no acute toxicity against zerafish, and the water quality of upper reaches of the Hun River in Dahuofang Reservoir and downstream estuary in Liaohe Park was well, which induced no significant genetic toxicity to liver cells of zebrafish. The water in lower reaches from Hun River of Shenyang, Liao River of Tieing and Panjin caused DNA damage of zebrafish liver cells respectively100%,30%,70%higher than the control, showed significant difference, and the water from the three places induced apparent genotoxicity to liver cells of zebrafish. The content of MDA, T-AOC and the activities of GST and GSH in zebrafish increased by47%,24%,21%and50%, respectively, the activity of SOD was restrain, and the inhibition ratio was more than20%, meanwhile. It was suggested that the more serious water pollution induced oxidative stress and increase of lipid peroxidation. The water pollution induced the oxidative damage in liver of fish is one of the important reasons for the genotoxicity.