Methodology And Case Study For Developing Water Quality Standards For The Protection Of Aquatic Ecosystems

Water for the protection of aquatic ecosystem was an important part of water quality criteria. Water guidelines for the protection of aquatic ecosystem of the United States, Canada, OECD (Organization for Economic Cooperation and Development), European Union Australian and New Zealand were analyzed, and assessment factor (AF), species sensitivity distribution (SSD) and toxicity sort were introduced particularly. Combination with a case study on a wetland reserve in Southern China,general steps to build water quality criteria for the protection of aquatic ecosystem were proposed:general international standards were used for physical and chemical and Inorganic indicators which has common view; joint probability curve (JPC) and three toxicology methods were used to assess ecological risk for organic indicators, especially for toxic and harmful substance. At last, a water quality standard for the protection of aquatic ecosystem was set up by combining attainability of the management goal.Water quality analysis of wetland reserve indicated that COD5, arsenic could reach the strictest international standard nowadays; 9 indicators of dissolved oxygen, conductivity, mercury, etc. could only reach the loose international standard nowadays; potassium permanganate index, copper, cadmium, etc. could even reach the loosest international standard. Thinking of the limit of monitoring index,112 kinds of water quality indexes were monitored in entry and exit of wetland reserve. Result of monitoring showed serious pollution of heavy metal and eutrophication.Combining the water quality analysis with general steps of building water quality criteria, the primary standards for the protection of aquatic ecosystem were presented. There were 77 kinds of indicators in the water quality standard, included 10 usual physical and chemical indicators,2 inorganic anion indicators,20 inorganic ion indicators and 45 organic matters.Finally, the methods to improve attainability of the management goal were proposed. Modelling for copper in the wetland reserve with box model showed that concentration can reach the standard of 3μg/L after 14 days. It took 9 days to reach the standard if it pretreated by constructed wetland.