Application Research Of Cu Toxicity And WQC Predicted By BLM In Typical Chinese Rivers

With the quick development of social economy and urbanization processe in China, existing states of heavey metals were altered in nature and its concentrations increased in water. Heavey metals in nature were difficult to decomposition or degradation, only to migration or transformation or bioaccumulation into biotas or settlement into sediment of rivers. With low concentrations heavey metals would not do harm to aquatic organisms. While it would be hazard to aquatic organisms even accured death when reached a critical concentration. Heavey metals bioaccumulated in organisms could also be harmful to other high grade organisms by food chain ecosystem, eventualy to human health. The biotic ligand model (BLM) was a direct and quantitative tool to assess site-specific metal bioavailability based on hydrochemistry and biologic sensitivity. Contamination accidents of heavy metals have happened frequently in China in recent years. It was imperative to study the application of BLM to Chinese rivers and aquatic organisms in order to establish proven technology of bioavailability assessment and scientific quality control criteria of heavy metals to protect aquatic ecosystem and human health. The content of this dissertation was as follows.Firstly, according to the present situations and development principle of BLM, there were two questions must be solved before BLM utilized to Chinese rivers. One was to enable more species which widly living in Chinese rivers adapt to BLM. The other was the BLM was applicable to water of Chinese rivers.Secondly, on the basis theory of BLM, a new technology was put forward to determine LA50which could be used to increase organisms species of BLM. That was to obtain LC50of a metal to an organism by toxicity tests in certain water, and use the speciation analysis function of BLM to compute the concentrations of toxic metal species accumulated on BL(Biotic Ligand) when the metal caused organisms50%mortality. Then LA50was acquired by summing the concentrations of toxic metal species accumulated on BL. LA50of copper to Oryzias latipes was12.43nmol/gw acquired by three96h acute toxicity tests of copper to Oryzias latipes performed by standard dilution water in laboratory.Thirdly, after widely investigation on typical rivers in China, water samples of the Yangtze river, the Yellow river, Xiangjiang river and Daliao river were collected. Water quality parameters were monitored and acute toxicity tests were performed simultaneity. The results showed that LC50observed and predicted had a certain difference of a factor within2in freshwater, which meaned that BLM could be used to predict LC50of copper to Oryzias latipes in typical Chinese rivers, LA50of copper to Oryzias latipes was accurate and the method of increasing species number in BLM by way of correcting LA50was scientific.Fourthly, Oryzias latipes were exposed successively to humic acid (HA), fulvic acid (FA) and their mixture of different concentrations for96h-LCso measurements. The results indicated that LC50of copper to Oryzias latipes increased with the increasing concentrations of HA or FA. Copper has less toxicity to Oryzias latipes in HA solution than that of FA with the same concentration which seemed that the compound effect of HA to copper had more stronger than that of FA. As the total concentration of HA and FA was constant, with the percent of HA increasing, LC50increased gradualy. When HA and FA in the same water, HA and FA had a certain promotion on copper toxicity. The predicted LC50by BLM would be more secure in general if the ratio of HA and FA assumed to be0.5when DOC compositions was unknown in natural waters and consisted mainly of HA and FA.Lastly, the results of BLM utilized to water of the Three Gorges Reservoir area and its upstream and Xiangjiang river and its tributaries which were two sensitive water in China showed that the order of LC50of copper to several aquatic organisms was Oryzias latipes> Rainbow trout>Daphnia magna>CerioDaphnia dubia>Daphnia pulex. Only considering copper in Xiangjiang river, the water quality of the site of Songbai Bridge, Chongling river, Upper reach of Chongling river entering Xiangjiang river, Lower reach of Chongling river entering Xiangjiang river and the section from Xiangtan to Changsha city was better. Waters from the site of Upper reach of Lei river entering Xiangjiang river in Hengyang city to Zhouzhou city had apparently ecology risks especially in the site of Zhuzhou city. In all sites, only the TU of Zhuzhou city was over1and dissolved copper concentration was0.48times more than CMC and1.38times more than CCC. So the deterioration of water ecological environment in Zhouzhou city was inevitable and organism species and quantity must decrease. All the TU was lower than1and dissolved copper concentrations were not over CMC and CCC in all sites of the Yangtze river. In52sites, the sum of sites whose TU>0.1was19, which showed that dissolved copper concentrations of these sites were in need of more attention. In16tributaries investigated, Daning river and Tuojiang river were obviously had influences on dissolved copper concentration of Yangtze river. Generally speaking, water quality of the Three Gorges Reservoir area and its upstream was better. But the concentration of dissolved copper was increased with the rising of water level. All of the results were accord with others studies which meaned the research conclusions of BLM were scientific.