| As a gathering place for carrying pollutants,the clay minerals and humus in the profile of the soil can play a role in filtering,affecting the decomposition,transformation and migration of the typical pollutants.In order to explore the influence of clay minerals and humus on the typical pollutants,the typical contaminated sites were selected to carry out fine sampling in the stratigraphic section.The contents and vertical distribution characteristics of clay minerals and humus were analyzed,and the pollution and risk level of pollutants in soil layer were evaluated by multivariate statistical analysis and potential ecological risk index method.Building a model to analyze the main factors which affecting the clay minerals,humus on the pollutants.The main conclusions are listed below.(1)The concentrations of the clay minerals followed the order of glimmerton >chlorite > kaolinite > montmorillonite > vermiculite > goethite > Hematite.The total clay mineral in agricultural areas were highest,followed by sewage irrigation zone,industrial area,landfill.The changes of clay mineral composition in soil profile is not obvious,they have samll difference in various stratigraphic sections,with the turning point of concentrations at 1 m,3 m,6 m.(2)Different types of sites have a significant effect on the soil humus and its components,and the sequence of the content of humus is shown as landfill >vegetable greenhouse > sewage irrigation zone > industrial area.The composition of humus in the soil decreased with depth,and the content of each component was Humin(HM)> Fulvic acid(FA)> Humilic acid(HA).The main changes occurred at0-6 m stratum,and the reductions of content below the height of 6 m became steadily.The ratio of HA/HF decrease with soil depth,with the sewage irrigation zone and industrial area have a high degree of humification.(3)The concentrations of the four heavy metals followed the order of Cr > Cu >As > Pb with variable coefficients ranging from 59.60% to 159.33% at 3-6 m stratum,which all displayed a high degree of variability.The risk level of the specific heavy metal followed the order of As > Cu > Pb > Cr,where As already showed a medium potential ecological risk in the studied area.The content of pharmaceuticals in different soil profile was significantly different,and the content of langfill was the highest,followed by the irrigation area and sewage irrigation area.The content of pharmaceuticals and heavy metals were reached 6.15 g/kg,118.42 mg/kg at 0-3 m stratum respectively,while 2.89 times for pharmaceuticals and 1.53 times for heavy metals at 6-15 m stratum.The decline of pharmaceuticals and heavy metals is only13.41%,19.15% at 6-15 m stratum.(4)Statistical analysis and redundancy analysis showed that the total explanation of clay minerals and humus to heavy metal was 55.4%.The explanation of HM,FA and HA were 17.7%,14.2% and 11.5% respectively,while the explanation of clay minerals belowed 6.5%.The total explanation of clay minerals and humus to pharmaceuticals was 45.5%.The explanation of HA/FA and HM were 19.1% and11.2% respectively.The concentrations of HA/FA and HM were positively correlated with the heavy metals and pharmaceuticals,and had a higher degree of influence,which were the main factors affecting the distribution of the pollutants. |
PDF Full Text Request