Establishment And Application Of The Short-term Methods For Estimating The Chronic Toxicity Based On Indigenous Organisms

Water pollution is one of the most serious problems in China. Industrial water discharges, wastewater discharges and agricultural water discharges are the three main causes of water pollution. Biological toxicity testing techniques which provide a comprehensive evaluation of biological effects of pollution water are widely used in the water quality monitoring and environmental risk assessment. The acute toxicity test can not reflect the chronic toxic effect of long-term exposure to low concentrations of pollutants, while the application of traditional chronic toxicity test is limited in the pratical work for it’s long and costly. So, the establishment of short-term methods for estimating the chronic toxicity has become one of the most important problems in the water pollution control works. In this paper, we do the ecology survey of the Yellow River and the Huaihe River, and screen out the typical indigenous organisms to whom the short-term methods for estimating the chronic toxicity is established. This method is then applied to the water quality evaluation and also applied to the environmental risk assessment of the pollution water in the future atmospheric conditions. The main results are as follows:1) The species identification results show that the dominant algae is diatom, while the dominant zooplankton is rotifer. Biodiversity index evaluation results show that the Huayuankou water source site is lightly polluted or non-polluted, while the Huayuankou monitoring section is seriously polluted, with other sections moderately polluted. Luminescent bacteria toxicity testing results show that some sections of the Jialu River and the Yellow River show low toxicity, while other sections of the Yellow and the Huaihe River show no toxicity.2) Based on the distribution characteristics of aquatic organisms, we choose the typical organisms Crucian carp, Navicula tenera and Daphnia pulex as the toxicity testing organisms. Through artificial propagation, we get the embryos and explore the culture conditions of the embryos. Navicula tenera and Daphnia pulex are first separated from the water and then cultured. Based on the above all, the short-term methods for estimating the chronic toxicity to indigenous organisms is established.3) The final effluent from a chemical industry still has toxic effects to the testing organisms, and toxicity results with indigenous organisms(Crucian carp、 Navicula tenera and Daphnia pulex) are the same to the result with common testing organisms. It means that the toxicity testing results with common organisms can be referenced during the water quality evaluation processes. In toxicity identification process, toxicity testing was performed to each treatment process and testing results show that different organisms have different sensitivity. Malformation types of embryonic development show that pericardial edema and yolk sac edema are the main malformation types with the embryos exposed to the raw water, pretreatment effluent and biological treatment effluent, while altered axial curvature to the enhanced coangulation effluent, which shows that the toxicity mechanism of raw water, pretreatment water and biological water is different from the enhanced coagulation water. The GC-MS analysis results show that there exists a large number of dinitroluene in the raw water and pretreatment water, it causes the toxicity, while the heavy metal and ammonia are not the toxicity reason.As the CO2concentration increased, the pH and Eh of the clean water and the arsenic pollution are significantly lowered compared to the ambience condition, while the pH and Eh of the sediment were also slightly lowered. The chronic toxicity results with Daphnia magna and Selenastrum capricornutum show that the toxic effects of the arsenic pollution water is enhanced. This says that the elevated CO2levels will increase the ecological risk of arsenic pollution water, but the mechanism needs to be further studied.