Application Of Sequential Extraction Methods For Speciation Analysis Of Heavy Metal In Sediments

Traditional Tessier sequential extraction method and the serial extraction method improved by the ultrasonic and microwave were used to analyze the heavy metal (Cu,Fe,Mn,Ni,Pb,Zn)speciation distributed in different sediment samples. Meanwhile,the transference and transformation rules of the heavy metals were also explored. The otherness of different methods were discussed through the contrastive experiments of different conformation .Through the condition experiments,the best extraction conditions of six heavy metals in sediments,which extracted by ultrasonic and microwave,were identified finally. The experiment took the recovery of the first four forms to justify whether they were suitable for the sediment samples. It showed that the recoveries of the first four forms in sediment from Jinji Lake by detecting heavy metals using two extraction methods were from 90% to 110%,which meant that the two methods applied in extraction different conformation of heavy metals in sediment were proper .We also used three extraction methods to determine several sediment samples from Suzhou city,The result showed that there's no significant differences were found between ultrasonic extraction and traditional extraction methods. And the ultrasonic extraction methods conformed to the actual situation,however,the microwave extraction methods would extract the behind forms in advance.The results of the ultrasonic extraction and traditional extraction methods showed that: Cu,Fe,Ni and Zn mainly existed in steady residual speciation;The speciation of Mn was evenly distributed in every speciation,the third form---bound to Iron and Manganese Oxides was accounted to be a great proportion,and this part of heavy metals has latent harm to the body of water and living creature;Pb content was also high in every speciation,especially in the high content of exchangeable, and it should be controlled on focus.The contents of six heavy metals in Jinji Lake sediment were more higher than those in the other three sediment samples, so they have the certain harm to the living creature and water environment.We also analysed the total quantity and dissolved heavy metals in surface water.The content of Cu element in Tai lake was up to the first grade of environmental quality standards for surface water. The content of Fe element in Qingjian lake was far above the standards for drinking water quality. The content of Mn element in Jinji lake was only slightly above the standards for drinking water quality. The content of dissolved Ni was above the standards for drinking water quality in three lakes, and much attention should be paid. The content of Pb element in three lakes were up to the third grade of environmental quality standards for surface water. The content of Zn element in Jinji lake was up to the second grade of environmental quality standards for surface water, and other three samples were up to the first grade.