Research On The Water Quality Standards And Application Of Zinc For The Protection Of Freshwater Aquatic Organisms In My Country

Water quality criteria reflect the actual environmental pollution caused by the pollutant by reporting the concentration of pollutant that can be accepted by a specific use of water.Water quality criteria are an important basis for ensuring the scientific formulation of water quality standards.It is also an important basis for different regions to evaluate,predict,control and govern environmental pollution in these areas.Zinc is an essential element for organisms and plays an important role in the metabolism of proteins,fats,nucleic acids and other substances.Aquatic organisms have less demand for zinc than human beings and are sensitive to the toxic effects of zinc.The water quality criteria for zinc and freshwater in different countries or regions are also more stringent than those of the human body.The exploitation and utilization of zinc in our country is great,and the exposure risk of zinc in the environment is far higher than that in other countries.Scientific water quality criteria/standards are needed to evaluate and manage the pollution of zinc.But research for water quality criteria in China is relatively lagging behind,mainly referring to foreign research and lack of experimental data.The results may not be able to guarantee the protection of Chinese freshwater ecosystems.In this study,data from experiment were combined with selected data to derive water quality criteria of zinc and make assessment of ecological risk of zinc in freshwater.The main work and results are as follows:(1)First,toxicity data of zinc obtained by different researchers after 1980 were screened following certain principles.Then Five Chinese native species Misgurnusangui Licaudatus,LimnodriLus hoffmeisteri,CipangopaLudina cahayensis,Macrobrachium nipponense,Bufo gargarizans were selected to conduct acute and chronic toxicological experiments of zinc.All the screened organisms were domesticated,pre tested and formally tested.After combining all of the above data,total data covered acute toxicity data of 28 families 41 genera 52 species and chronic toxicity data of 13 families 17 genera and 17 species.Finally,water quality criteria for the protection freshwater organism were derived using species sensitivity distribution method.The results showed that the derived short-term and long-term water quality criteria for zinc were 102.33 and 25.03?g/L,respectively.(2)After obtaining the reference value of zinc,the exposure concentration of zinc in natural water body in different regions of China in recent years was collected.Four different ecological risk assessment methods were used to assess the ecological risk of zinc in aquatic environments to aquatic organisms.Zinc has some ecological risk to aquatic organisms in these natural water bodies.At the same time the reference value with the current standard of surface water quality were compared.The reference value is lower than the water quality standard of class II and III water zinc standard(1000 g/L),the water standard of our country current may lead to "under protection" phenomenon of the freshwater aquatic organisms.