The Acute Toxicity Study And Applications Of Water Environment Based On Scenedesmus Quadricauda

II Water environment problem has become a global environmental problem,and the water quality shortage has become the principal problem facing the country. Garbage, sewage, pesticides, oil and other toxic substances could entered the food cycle system through ground or surface water system easily, and these pollutants may be absorbed by human or animal by way of digestive system and respiratory system or skin channels. Untreated or inadequately treated industrial waste water and domestic sewage discharged into water bodies which made an impact on human health, such as acute and chronic toxicity and carcinogenic effect arose from mercury, cadmium, arsenic, pesticides, and the occurrence of water borne disease. Therefore, the establishment of timely and accurate monitoring of water pollution means is an embodiment of "people-oriented" thinking and has an important role on human body health.Usually, there are two ways to monitor aquatic environments: physics/chemistry and biology. Biological monitoring technology is using the sensitivity of aquatic organism on hazardous substances, through analying the corresponding changes of different aquatic organisms in different conditions of circumstance, then got the results of qualitative assessment of water quality. Biological detection can synthesize the interaction effects of many toxic substances; determine the direct relationship between the concentration of toxic substance and biological effects, which provide a scientific basis for monitoring and comprehensive evaluation. In addition the acute toxicity test can prove up a short time damage of organism caused by contacting with environmental pollutants, identify pathways and dose-effect relationship, which provide design basis for other animals and early warnings of environment pollution, then has become the most widely used methods of toxicity testing.Algae is a primary producers, it is a kind of ideal biological toxicity test materials for its small size, rapid reproduction, sensitivity to the poison, isolation and culture easily. Heavy metals and organic pollutants in water made an impact on photosynthesis, respiration, enzyme activity and growth of algae, etc. At Persent,the pollutions of heavy metals,organic matters and their mixtures are the main environmental problems in water. But more researches were carried out on the pollution of single heavy metal and organic matters more than their mixtures.According to the biological response characteristics of microalgae exposed to pollutants, this experiment measured the single and joint influences of some heavy metals, organic compounds, pesticides on chlorophyll concentration and light energy conversion efficiency of Scenedesmus quadricauda, studied the acute toxicity effects of pollutants on algae within 30min. Also introduced an application of acute toxicity analysis technology in natural water, combined with sampling an "algae bloom" area in Yangtze River, which laied the foundation for establishing a sensitive, rapid, efficient, low-cost method, for the water environmental safety framework, and background values and safe capacity of river, then provided a scientific basis and means for establishing a safety warning, forecasting system of river basin water environment.