工矿区不同类型生物结皮对大气降尘重金属的富集规律及其影响因子

大气降尘是矿区土壤重金属的主要来源，而生物结皮对大气降尘重金属有显著的富集作用。为探究不同类型生物结皮对大气降尘重金属的富集规律及其影响因子，选取宁东典型火电厂周边生物结皮广布区作为试验样地，3类生物结皮作为研究对象，并以临近裸土作为对照，对比分析了生物结皮富集大气降尘过程中土壤理化性质、酶活性及重金属含量的变化，采用相关分析、冗余分析和方差分解方法探讨了不同类型生物结皮的结皮层(A层)和层下土壤(B层)重金属含量与其土壤物理、化学性质及酶活性之间的关系。结果表明：燃煤烟尘是矿区大气降尘重金属污染的主要来源，涉及重金属元素包括Cd、Cr、Hg、Pb、Zn、As。生物结皮对源自大气降尘的重金属元素均具有显著的富集作用，且在不同演替阶段生物结皮间的富集规律完全一致：藓结皮>混生结皮>藻结皮；重金属综合污染指数评价结果显示：生物结皮对重金属具有表层富集效应，表现为A层污染程度高于B层。不同类型生物结皮A、B层综合污染指数存在显著差异，排序为：藓结皮>混生结皮>藻结皮；和对照相比，三类生物结皮均能通过富集大气降尘增加其A、B层养分和细颗粒物含量并改善土壤质地。方差分解结...

Enrichment law of atmospheric dustfall heavy metal pollution by different types of biocrusts in mining areas and its influencing factors

Atmospheric dust fall is the main source of soil heavy metals in mining area. Biocrusts have a significant enrichment effect on heavy metal. In order to explore enrichment laws of how biocrust at different succession stages capture and concentrate heavy metals from atmospheric dust fall and its influencing factors, biocrusts wide-spread area around typically thermal power station in Ningdong Energy Industrial Base were taken as experimental site, three types of biocrusts were selected as study objects, and bare soils nearby were set as control. Based on the comparison analysis of changes of soil physicochemical properties, enzyme activities and heavy metal contents during the process of the enrichment of atmospheric dust fall by biocrusts, the relationship between heavy metal contents and soil physicochemical properties, enzyme activities of biocrustal layer (A horizon) and subsoil (B horizon) were analyzed by using the methods of correlation analysis, redundancy analysis and variance partitioning analysis. The results indicated that, flue gas was the main source of atmospheric dust fall heavy metal pollution, the involved heavy metal elements including Cd, Cr, Hg, Pb, Zn, As. Biocrusts had significant enrichment effect on heavy metal elements derived from atmospheric dust fall, and demonstrated a totally consistent law among biocrusts of different types as followed Moss crust >Mixed crust >Algal crust. The comprehensive pollution index indicated that biocrusts had a certain surface enrichment effect on heavy metals, which demonstrated as A horizon had a higher pollution level than that of B horizon. Compared with control, the three types of biocrusts all could enrich atmospheric dust fall and increase the nutrient, fine particles and improve its soil textures of A and B horizons. Variation partitioning results indicated that soil chemical properties were the single environmental variables of the highest degree of explanation influencing the heavy metals content. Redundancy and correlation analysis showed that soil organic matter, electrical conductivity, enzymatic activity, bulk density were the main environmental factors that influenced the heavy metals content in A, B horizons of different biocrusts.