Study On Soil-environmental Effects Of Seasonal Frozen Swamp Turfy Soil Under Influences Of Line Projects

Turfy wetland is a relatively special marsh wetland,mainly distributed at high latitude areas and cold highland area.By the action of microorganism,plant residues transformed into humus deposited in the basin as well as part undecomposed plant residues.With the continuous development of economy,many line projects inevitably invaded turfy wetlands,causing a series of environmental problems,such as the foundation can cut off hydrological supply resulting in wetland drainage;engineering and transportation bring many pollutants such as heavy metals and organic contamination which can severely affect the ecosystem of turfy wetland;line projects such as highway,freeway and railway also cause the decline in wetland area the fragmentation of wetland area.The damage to turfy wetland ecosystem means undermining local biological support,stable climate and ecological balance which could result in a series of negative effects on the local economy and people's life and cause long-term immeasurable loss.At the same time,the researches on turfy soil mainly focus on its engineering properties and deformation and stability of subgrade settlements with little attention of environmental effects.Therefore,it is necessary to study the environment effects in order to ensure the harmonious development of line engineering activities and turfy wetlands.Based on the above reasons,this study chose turfy soil as research object,funded by NSFC?Natural Science Foundation of China?,systematically studied soilenvironmental effects of seasonal frozen turfy swamp under the influence of line projects,including the effects of physical and chemical properties of turfy soil,heavy metal pollution,changes in soil microorganisms.Soil samples were sampled at different distances away from line projects then relevant tests were carried on,came to the conclusion as follows:1.Line projects would cause several effects to physico-chemical properties of turfy soils.Influences are more apparent for density,water content and organic matter content: in the influence area?close to highway?,soil density are much larger while water content and organic matter are much lower than background level;PH value and the degree of decomposition haven't showed unified changing pattern with the construction of highway;2.Line projects could lead to enrichment of heavy metals in the roadside turfy soils.The concentrations are as the following sequence: Zn>Cr>Ni>Cu>Pb>Cd,the content of Zn is between 170 to 830 mg?kg^-1,for Cd,0.6¹.1 mg?kg^-1;Combined with background values in Jilin Province,Indexes of Geo-accumulation?Igeo?were calculated to evaluate the pollution levels of each elements.Results show that the pollution of Cd is most serious,at all the 4 sampling sites,Cd reaches moderately polluted while the contaminations of Pb haven't reached pollution level,for other elements,contamination conditions are related to the sampling sites;correlation analyses indicate that there is a positive correlation between Ni,Zn,Cr and Pb,which means these elements may have common resources;the adsorption analyses show that the adsorption capacity of turfy soil is positively related to organic matter content while has little correlation with PH and water content;3.The microorganism is greatly developed in turfy wetland,the quantities follows the sequences: bacteria > actinomycetes > archaea and much larger than the population of fungi.Bacterial quantity reaches 105 copies/g and in most cases,the quantity of bacteria in surface soil is larger than deeper layer;microorganism would show a series of response when facing environmental stresses caused by line projects.When the degree of interference is below the resistance and resilience of microbial communities,the population of microorganism at impact region is larger than background value.When the disturbance degree is beyond the resistance and resilience,microbial quantities would greatly reduce;in addition,line projects would cause a decline in diversities of microbial population.The abundance of microbial diversities is also related to sampling sites,assuming paludification meadows > forest and shrub swamps.In this study,Jiangyuan turfy wetland has the largest abundance of microbial communities.