黄河三角洲不同土地利用方式下土壤重金属分析评价

Analysis and Evaluation of Heavy Metals in Soils Under Different Land Use Patterns in the Yellow River Delta

为研究河口三角洲不同土地利用方式下土壤中重金属的分布规律,选取黄河三角洲为研究对象,对湿地、退耕还湿、林地、农田4种不同土地利用方式下28个样点的0~60 cm土壤进行分层取样,测定土壤pH、粒径、有机质以及8种重金属的含量(As、Cd、Cr、Ni、Cu、Pb、Zn、Mn)。结果表明:土壤中As、Cd、Cr、Ni、Cu、Pb、Zn、Mn的平均含量分别为9.86、0.13、55.49、25.81、12.63、16.59、55.94、498.80 mg·kg^(-1),其中Cd是超标最严重的金属,As、Cd、Ni、Pb、Mn的含量在不同用地类型间差异显著,可能由于受海水影响,As元素在东部沿海区域含量较高,Cd、Cr、Ni、Zn、Mn含量分布南高北低,湿地和退耕还湿土壤中As含量明显高于同一深度的林地和农田,除As和Cd外,其他重金属在农田的含量显著高于其他用地类型。相关性分析表明:Cr、Ni、Cu、Zn、Cd、Mn、Pb的来源相同或相似,As与它们的来源不同;颗粒物粒径越小越易吸附重金属。内梅罗综合污染指数表明,研究区存在不同程度的污染,且污染程度随深度增加而减小。

In order to understand the heavy metals distribution in soils of delta under different land use,the Yellow River Delta was selected as the study area.Four land use types were chosen,including wetlands,restored wetland,forest land,and farmland.Soil cores were collected at the depth of 0-60 cm and broken six soil layers at 10 cm intervals in 28 sites.Concentrations of metals(i.e.As,Cd,Cr,Ni,Cu,Pb,Zn,and Mn),pH,particle size and SOM were determined.The results showed that the mean concentration of As,Cd,Cr,Ni,Cu,Pb,Zn and Mn in soil were 9.86,0.13,55.49,25.81,12.63,16.59,55.94,498.80 mg·kg^(-1),respectively.Among these metals,Cd was the metal with the highest concentration above the background values.Concentrations of As,Cd,Ni,Pb and Mn were significantly different among different land use types.The concentrations of As were higher in eastern coastal areas due to the influence of seawater.The spatial distribution of metals in the Yellow River Delta indicated that concentrations of Cd,Cr,Ni,Zn,Mn were higher in south part of study area.The concentrations of As in wetland and restored wetland were higher than that in forest land and farmland in the same soil depth.Except As and Cd,other metals were higher in farmland.The correlation analysis illustrated that the sources of Cd,Cr,Ni,Cu,Pb,Zn,and Mn were similar,while there were different sources for As.Metal concentration were closely related to fine particles.Nemerow comprehensive pollution index clarified that there were metal pollution in the study area,and the pollution level decreased with depth.