贵州省城市污泥重金属组成特征与农用风险评价

分别选取了贵州省7个主要城市的10个典型污水处理厂脱水污泥样品进行检测，统计了2009~2012年污泥中重金属Cu、Zn、Pb、Cd、Ni、Cr、As、Hg的含量。结果表明，城市污泥中重金属含量受到各地区工矿业发展的影响，部分重金属在某一污水处理厂出现了远大于其它地区的极值，具有明显的地域特征。2009~2012年贵州省城市污泥重金属的变化表现为As、Hg呈升高趋势，其它重金属变化趋势不明显，As、Hg升高可能是因为贵州省近年来燃煤消耗量增加，烟气排放污染所致。对污泥重金属的农用风险评价显示，贵阳中部（S2）、黔西地区(S9)污泥农用重金属的生态风险较高，不推荐直接施用，其它各地区污泥农用风险较低，可以进行农用，建议各污水处理厂应根据本地区污泥重金属特征制定合理的污泥处置措施

HEAVY METALS COMPONENT IN SEWAGE SLUDGE AND ITS POTENTIAL ECOLOGICAL RISK ASSESSMENT FOR AGRICULTURE IN GUIZHOU PROVINCE,CHINA

In this study,the sewage sludge samples were collected from ten typical sewage treatment plants of seven major cities in Guizhou Province from 2009 to 2012.The contents of heavy metals such as Cu,Zn,Pb,Cd,Ni,Cr,As,Hg were measured.The results showed that,in Guizhou Province,concentrations of Zn,Cd in sludge were higher than the control standard GB4284-84 (pH ≥65) and other heavy metals concentration in sludge were lower than the standard.Local manufactures and mining were found to exert impacts on heavy metals levels in sewage sludge in different plants.For example,in central region of Guiyang(S2),being affected by electroplating industries,the content of Zn,Cd,Cr in sewage sludge were much higher than those in other regions.In eastern region of Guizhou (S7),mercury mining leaded to an extremely higher concentration of Hg in regional sewage.The content of Pb,Cd of heavy metals in sewage sludge reached extreme value in western of Guizhou,where industry were dominated by lead zinc mining and coal mining.From 2009 to 2012,the rates of increase in As,Hg in sludge were 3622% and 8812 % respectively.It is probably because a large number of power plants had been built in recent years in Guizhou Province.Flue gas emissions could also result in As and Hg contamination in sludge.Except As and Hg,other heavy metals content in sludge didnt show obviously change during this 4 years.The Potential Ecological Risk Index (RI) and Nemerow Index (PN) were selected to assess the agricultural risk of using sewage sludge.The RI results showed that,in middle Guiyang (S2) and western Guizhou (S9),the RI index reached 4941 and 4270 respectively,suggesting an ecological risk of using sewage sludge for agriculture in these areas.Nemerow Index (PN) showed a same trend as RI.Therefore,these two kinds of sludge are not recommended for direct agricultural application to avoid environmental pollution.According to heavy metals content level and characteristics of sludge in different sewage treatment plant,sludge disposal measures should be reasonably selected