Construction And Application Practice Of Quality Control System On Monitoting Of Heavy Metals In Sediments Of Rivers,Lakes And Reservoirs

Construction of quality control system is the guarantee of acquiring accurate monitoring results in environmental monitoring.At present,the standard of Quality Control System On Monitoring Of Heavy Metals In Sediments Of Rivers And Lakes has not been established in China,which cannot meet the requirements of contemporarily environmental monitoring.To exactly specify each process in monitoring sediments of rivers,lakes and reservoirs,to ensure the accuracy and reliability of environmental monitoring data,to provide scientific,fair,accurate,and efficient functions for decision-making in environmental management,it is necessary to construct a set of quality control system on monitoring heavy metals in the sediments of rivers,lakes and reservoirs.In this paper,quality control system for monitoring heavy metals in the sediments of rivers lakes and reservoirs are constructed preliminarily,and then case studies were carried out about the monitoring on heavy metals in the sediments of tributary of Liujiang River and Dawangtan reservoir.The research results are as follows:(1)Preliminary construction of quality control system for monitoring of heavy metals in the sediments of rivers and lakes.In reference to quality control measures in samples collection and the samples analysis both at home and abroad,the integration and perfection of quality control measures are carried out on existing specification and standard that are the independent or dispersed or not included in a system,by proposing the new ideas,such as comparing between samples collected in different laboratories,preparing standard parallel samples,analyzing samples by labelling standard parallel samples and other quality control measures,and eventually quality control system of monitoring on heavy metal in the sediments of rivers and lakes has been established.The system includes a point arrangement,sampling,sample transport and transfer,sample preparation,sample analysis and data processing,which is quality control system aimed at the whole process of monitoring of heavy metals in sediments of river,lakes and reservoirs.(2)For the first time the quality control system is applied for the whole processes of monitoring heavy metals in sediments in rivers,lakes and reservoirs in Guangxi Province.The tributary of Liujiang River and Dawangtan reservoir are selected for monitoring heavy metal in sediments,and the contamination does not occur in the processes of sample collection,transport,transfer and preparation from water monitoring section.Moreover,in the process of analyzing samples,the measures include samples preparation and analysis,pre-analysis,method validation,drawing standard curve,limit of detection,blank test,precision control accuracy control and others,which has verified feasibility and operability of system.(3)Establish ICP-MS that can determine 10 kinds of heavy metal elements in sediment of Cu,Zn,Pb,Cd,As,Ni,Cr,and Mn,Sb and V by controlling each process that will impact the analysis condition and in accordance with the requirements of quality control.Results showed that when grain diameter of samples are 100 mesh,digestion system are Nitric Acid-Hydrochloric Acid-Hydrofluoric Acid,measured elements are isotopes with high sensitivity,and 103Rh for works as standard correction elements,these 10 kinds of heavy metal elements have a good linear relation,with correlation coefficient R varying between 0.9999?1.0000,detection limitation varies between 0.001 mg/kg?0.033 mg/kg,while elements cannot be detected or below detection limitation in laboratory blank samples;relative deviation of parallel samples varies between-8.7%?2.4%,addition standard recovery for each element are at a ratio of 81?107%,the relative standard deviation is within the range of 0.18%?7.9%,the results are all within the reference range.It means through the implementation of quality control activities,the results of 10 heavy metals in sediments obtained are accurate and reliable.(4)Confirming the method of measuring Hg element in mercury instrument combine with index requirements of quality control.When grain diameter of samples is 100 mesh,the standard curve has a good linear relation,with correlation coefficient R of 0.9998,relative deviation of parallel samples varies between 0.031%?2.4%,relative standard deviation of standard samples is 2.5%,that is the test results are within the range of reference value,and the test results of elements Hg in sediment are accurate and reliable.