山东南部海滩沉积物重金属污染评价及磁学诊断

EVALUATION AND MAGNETIC DIAGNOSIS OF HEAVY METAL POLLUTION IN SEDIMENTS OF BEACHES IN SOUTHEASTERN SHANDONG PROVINCE

海滩作为海陆交汇和人类活动最为频繁的区域之一,由于排污、附近工厂和垃圾倾倒等造成的重金属污染问题亟须重视。以山东南部日照市海滨国家森林公园、芙蓉村、涛雒镇三个海滩为例,对其表层与垂向沉积物中的Cr、Ni、V、Fe、Zn、Co、Pb共7种重金属含量进行测试,并使用污染负荷指数(pollution load index,PLI)法与地质累计指数(I_(geo))法进行评价。同时对样品进行环境磁学参数测试并建立海滩沉积物重金属污染的磁学诊断模型。PLI显示,三个海滩均处于污染状态,污染程度为森林公园海滩<芙蓉村海滩<涛雒镇海滩。I_(geo)结果表明,森林公园海滩存在V污染,污染样品占比18%;芙蓉村海滩存在Ni和V污染,污染样品占比约33%;涛雒镇海滩存在Cr、Ni、V污染,污染样品占比约38%。研究区海滩重金属污染产生的主要原因为当地的工业生产以及水产养殖废水排放。磁参数归一化多元线性分析显示,质量磁化率χ、饱和等温剩磁SIRM、非磁滞剩磁磁化率χARM三个参数和重金属元素含量关系密切,可以较好指示重金属含量和污染程度。质量磁化率诊断结果表明,当日照市海滩0.063~0.125 mm粒级沉积物磁化率值大于1000×10^(-8)m^(3)/kg时,需要注意海滩可能存在重金属元素污染,可进行更深一步的污染评估。

Beach areas are prone to heavy metal pollution caused by human activities.We studied three beaches,namely Rizhao Seashore National Forest Park Beach(FPB),Furong Village Beach(FVB),and Taoluo Town Beach(TTB)in the southeastern Shandong Province as study areas.The contents of Cr,Ni,V,Fe,Zn,Co,and Pb on ground surface and in sediments were detected and evaluated using the pollution load index(PLI)and the index of geoaccumulation(I_(geo)).Additionally,environmental magnetic parameters were measured on the samples,by which a magnetic diagnostic model for heavy metal pollution in beach sediments was established.Results show that all the three beaches were polluted as indicated by PLI,and the degree of pollution was in an ascending order of FPB<FVB<TTB.In addition,Igeo data show that the FPB suffered from V pollution and 18%of the samples were contaminated;FVB was Ni and V polluted as shown in about 33%of the samples;and TTB was Cr,Ni,and V polluted shown in about 38%of the samples.The main causes of heavy metal pollution in the study areas were local industrial production and aquaculture wastewater discharge.Normalized multivariate linear analysis of magnetic parameters showed that the three parametersχ(mass specific magnetic susceptibility),χ_(ARM)(susceptibility of anhysteretic remanent magnetization),and SIRM(saturation isothermal remanent magnetization)were closely related to the content of heavy metal elements,and they can better indicate the content of heavy metals and the degree of pollution.Shown by mass magnetic susceptibility diagnosis,theχvalue of 1000×10^(–8) m^(3)/kg in fine-grained sediment(0.063~0.125 mm diameter)should be a warning sign of heavy metal pollution,to which thorough pollution assessment is suggested.