Distribution Characteristics And Correlations Of Heavy Metals In Wet And Dry Depositions In Main Cities In Guizhou

In order to understand the pollution levels of heavy metals in wet and dry depositions samples and the interaction between the heavy metals in wet and dry depositions during the atmospheric process,wet and dry deposition samples were collected successively and monthly from March 2015 to February 2016 in major cities（Guiyang,Anshun,Bijie,Zunyi,Duyun,Panxian）in Guizhou Province.Heavy metals（Zn,Mn,As,Cu,Ni,V,Cr,Cd）were analyzed by inductively coupled plasma mass spectrometer（ICP-MS）.Seasonal variations of heavy metals were explained,the sources of heavy metals in wet and dry depositions were analyzed,the correlation of the same element in wet and dry depositions was discussed.The main conclusions as following:（1）The rainfall of study areas ranged from 599.1mm to 1260.1mm,p H values of wet depositions ranged from 6.06 to 7.94,dustfall ranged from 34.8g?m^-2 to 135.4g?m^-2.For seasonal variations,the rainfall showed the highest in summer,then in spring and autumn,while the lowest in winter.The p H values in wet depositions showed highest in summer and lower in spring and winter.The dustfall showed the highest in spring while the lowest in winter.（2）The concentration of heavy metals in wet depositions ranged from 0.03μg?L^-1 to 193.05μg?L^-1,and Zn had the highest concentration,followed by Mn,Ni,As,Cu,Cr,V and Cd.Compared toⅠclass water in the surface water environment quality standards,Zn,As,Cu in wet depositions exceed the standard in winter.The concentration of heavy metals in dry depositions ranged from 3.05mg?kg^-1 to 17051.16mg?kg^-1,and Zn had the highest concentration,followed by Mn,Cu,Ni,Cr,As,V and Cd.Compared with the local soil background values,Zn,Ni,As,Cu,Cd was seriously exceeded.For seasonal variations,most heavy metals in wet depositions showed the highest concentration in spring while the lowest in summer.However,there were no significant seasonal variations in dry depositions.From the spatial distribution,the concentrations of heavy metals in wet depositions decreased in the order of Guiyang,Bijie,Zunyi,Anshun,Duyun,Panxian and the concentrations of heavy metals in dry depositions decreased in the order of Anshun,Zunyi,Duyun,Panxian,Guiyang,Bijie.（3）The source of heavy metals in wet and dry depositions was discovered by the principal factor analysis and other methods.The main sources of heavy metals in wet depositions are traffic activities,building dust and coal burning（78.83%）while are traffic activities（41.37%）,building dust（21.45%）and mixed sources of ground and coal burning（37.18%）in dry depositions in Guiyang.The main source of Guiyang high slope are traffic activities（57.89%）and coal burning（41.12%）in wet depositions and the main source is ground dust（46.10%）,secondly are traffic activities（26.99%）and coal burning（26.91%）in dry depositions.The heavy metals in wet and dry depositions at Anshun,Zunyi,Panxian come from traffic activities,coal burning and ground dust（in wet depositions: 91.04%,89.56%,91.98%;in dry depositions:77.10%,99.00%,73.92%）,while come from coal burning,traffic activities,building dust and ground dust（in wet depositions: 89.17%,99.99%;in dry depositions: 96.52%,95.20%）in wet and dry depositions at Anshun Electricity City and Bijie Institute of agriculture research,while come from traffic activities,building dust and ground dust（in wet depositions: 93.57%;in dry depositions: 89.89%）in wet and dry depositions at Bijie monitoring station.The main sources of heavy metals are traffic activities（37.43%）,and coal burning（57.99%）in wet depositions and the main sources of heavy metals are traffic activities（42.58%）,ground dust（36.59%）and coal burning（20.83%）in Duyun.（4）The amounts of heavy metals in wet depositions ranged from 21.25 mg?m^-2 to 57.66 mg?m^-2 and in dry depositions ranged from 52.53 mg?m^-2 to 194.20 mg?m^-2.For seasonal variations,the number at summer and spring are higher than autumn and winter in wet depositions and the amount of heavy metals in dry depositions is different from different areas.The range of heavy metals from high to low is Guiyang,Panxian,Bijie,Duyun,Zunyi in wet depositions and the amounts of heavy metals that contained in dry depositions from high to low are Bijie,Zunyi,Duyun,Guiyang,Panxian.（5）By analyzing the correlation of heavy metals in wet and dry depositions,it shows that they are related to the rainfall,dustfall,the concentration of elements and the form of existing.