Effects Of Atmospheric Dustfall Around A Coal-fired Power Plant On Soil And Greening Tree Species

In order to illuminate the effects of atmospheric dustfall around thermal power plant on greening tree species and soil,we take surface soil and atmospheric dustfall samples from different distances in the prevailing wind direction around Maliantai power plant in Ningdong base and five major green tree species as study objects.Through field study and laboratory experiments,we analyse particle size distribution of soil and atmospheric dustfall at different distances,changing characteristics of nutrient and heavy metal contents,and the five green tree species’ variational characteristics,such as dust retention ability,leaf surface microstructure and photosynthetic characteristics,so as to reveal the rule of the interaction between atmospheric dustfall on soil and tree species around thermal power plants,providing basic data and theoretical guidance for selecting tree species and taking comprehensive evaluation of environmental quality in local industrial parks.The main findings are as follows:(1)According to analysis of atmospheric dustfall particle size distribution and mineral composition.The composition of atmospheric dustfall was complex,which included the dustfalls of natural resources and artificial resources.The dustfall of natural resources was mainly from domestic sand dust,and the main components of which were Quartz,Calcite,Plagioclase,Chlorite and Kaolinite,etc.The dustfall of artificial resources was mainly from flue gas,and the main components of which were related to Ag,Co,Mn,Cr,Pb,As,Cu,Silicon disulfide and some polycyclic aromatic hydrocarbons(PHAs),etc.Organic matter content,total N content and heavy metal content at a higher level in atmospheric dustfall.Particularly,there were strong ecological risk of heavy metals.(2)The particle size distribution curves of soil demonstrated abnormal and bimodal and multi-peak distribution status at various distances,which indicated that the compositions of soil were from multiple sources.The soil fractal dimension around power plant between 2.41 and 2.56,show that soil texture type was typical sand.Organic matter content,total N content and heavy metal content at a higher level in soil.Particularly,there is a strong ecological hazard risk of heavy metals.Particularly,heavy metal content was generally higher than the background value of soil heavy metals in Ningxia,which had strong ecological risk.(3)Because different greening tree species laid the surface microscopic structure of different dustfall retention ability in their respective have obvious difference.The dust detentions of greening tree species will be stronger,while leaves were more surface microstructure,grooves and bumps in the more dense structure.The difference of leaf surface microstructure also leaded to the selection and retention of different particle size and mineral composition in atmospheric dustfall.Dust retention could inhibit the tree species’ photosynthesis,but different tree species had different tolerance and adaptability to atmospheric pollutants.(4)The fractal dimension of atmospheric dustfall and soil was a significant positive correlation,which showed that the fractal dimension of soil would increased when atmospheric dustfall of particle size was lowering.Nutrients carried by atmospheric dustfall deposited into the soil changed soil nutrients supply,of which the soil organic matter was the most significant.Pearson correlation coefficients showed that Cr and Cu in the atmospheric dustfall were poor positively related to the Cr and Cu in soil.The coarse distribution of atmospheric dustfall particle size around Maliantai power plant is related with the dust retention ability of surrounding green trees that dominated by stomatal adsorption type,and the fine particles that are easy to be retained by green trees.Ailanthus altissima can be used as the preferred tree species for landscaping in Ningdong base,because its dust retention ability was significantly higher than that of Rhus typhina,Fraxinus chinensis,Maackia amurensis and Ulmus pumila as its rough leaf surface and high stomatal density.F.chinensis and M.amurensis had good retention effects on heavy metal minerals and polycyclic aromatic hydrocarbons in atmospheric dustfall,therefore they can also be priority tree species for landscaping in Ningdong base.A.altissima and M.amurensis should be given priority for afforesting as their outstanding roles in resisting dust pollution in the vicinity of the thermal power plant.