The Aquatic Organism Criteria For Zn²⁺ And Cd²⁺ In The Poyang Lake Basin

Acute toxic experiments of four organisms,Daphnia magna,Macrobrachium nipponense,Ctenopharyngodon idellus,Scenedesmus quadricanda,with Poyang lake original water had been carried to find out the LC₅₀ and EC₅₀ of zinc and cadmium.In addition,combined with the existing zinc and cadmium toxicity data of aquatic organisms distributed in poyang lake,which is selected from database,the water quality criteria of zinc and cadmium have been figured out by SSD and WER.The results of the study showed that:?Comparing the average value of LC₅₀ of different organisms,the tolerance degree of Zn²⁺in different organisms is as following:Macrobrachium nipponense>Ctenopharyngodon idellus>Scenedesmus quadricanda>Daphnia magna;The tolerance of Cd²⁺in different organisms is as following:Ctenopharyngodon idellus>Scenedesmus quadricanda>Daphnia magna>Macrobrachium nipponense.?The toxic intensity of Zn²⁺in different original water is as following:Sanjiangkou>Xihai>Raohe>Wuchengn>Hukou.The toxic intensity of Cd²⁺in different original water is as following:Xihai>Raohe>Sanjiangkou>Wucheng>Hukou.?In addition,the acute lethal concentrations of Zn²⁺for Poyang Lake basin have been derived as the CMC is 0.136mg/L and CCC is 0.033mg/L;that of Cd²⁺is2.096?g/L and 0.243?g/L,respectively.?Lacking enough chronic toxicity data,the WER method is a preferred derivation method.?Surface water quality standards of Class II-V,by fishery water quality standards cannot guarantee that the Poyang Lake basin organisms are not endangered by the toxicity of Zn²⁺and Cd²⁺.