Spatial and Temporal Variation of Atmospheric Deposition Pollution in Xi'an City

YANG Wenjuan; CHEN Ying; ZHAO Jianqiang; HU Bo

doi:10.3969/j.issn.1003-6504.2017.03.002

Abstract：In order to investigate the dustfall flux,heavy metal pollution condition,spatial and temporal variation of atmospheric deposition in Xi'an City,samples were wet collected at four control points of national ambient air quality located in industrial zone,commercial zone,cultural and educational zone and scenic zone month by month in 2014.The concentration of heavy mental such as Pb,Zn,Cu,Cr,Ni and Cd was tested with ICP-MS simultaneously.The results indicated that the atmospheric deposition pollution in Xi'an was serious.The annual average dustfall flux in industrial zone,commercial zone,cultural and educational zone and scenic zone was 17.84 t/(km2·(30 d)),15.99 t/(km2·(30 d)),15.46 t/ (km2· (30 d)),11.76 t/(km2· (30 d)),much higher than foreign related standard.Dust fall flux changed with seasons significantly,with the affected order as winter＞spring＞summer＞autumn.Dustfall flux also varied in studied function zones greatly except in autumn,with the largest quantity in industrial zone,then in commercial and cultural and educational ones,the smallest in scenic zone.Furthermore,the average concentration of Pb,Zn,Cu,Cr,Ni,Cd in atmospheric deposition was 438.1 mg/kg,454.9 mg/kg,61.1 mg/kg,149.5 mg/kg,41.4 mg/kg and 7.8 mg/kg respectively,which was 20.5,6.6,2.9,2.4,1.4 and 83.0 times of the soil background value in Shaanxi Province.Pollution of Pb,Cr,Cd was serious and distinctly enriched.Concentration of Pb and Zn did not dynamically change with seasons,while the concentration of Cu,Cd,Ni was highest in winter,lowest in summer and autumn.Concentration of Cr in winter was much higher in other seasons.Spatial variation of heavy metal concentration in dustfall in Xi'an was not significant due to the indistinguishable partition of functional zones and upper air circulation.