长春市城区重金属大气干湿沉降特征

为弄清长春市城区重金属大气干湿沉降特征,于2006年5月26日—2007年6月12日采用被动采样技术分采暖期和非采暖期共收集大气干湿沉降样品24件,采用全谱直读电感藕合等离子发射光谱法(ICP-AES)和原子荧光光度法(AFS),分析了其w(As),w(Hg),w(Cd),w(Cu),w(Pb),w(Zn)和w(Cr).结果表明:长春市大气干湿沉降样品中w(As),w(Cd),w(Cr),w(Cu),w(Hg),w(Pb)和w(Zn)分别为38.9,2.24,92.3,76.2,0.27,115.2和462mg/kg,均明显高于表层土壤,且w(Cu),w(Hg),w(Pb)和w(Zn)在采暖期均显著低于非采暖期;经估算,As,Cd,Cr,Cu,Hg,Pb和Zn大气年干湿沉降量的平均值分别为4.79,0.25,10.67,8.22,0.030,12.31和48.15mg/(m2.a),明显高于北美和欧洲,且As,Cd和Cr在采暖期的日均干湿沉降量高于非采暖期;根据目前的重金属大气干湿沉降速率估算,重金属大气干湿沉降有可能造成长春市表层土壤中重金属不同程度的累积,其中Zn的累积最为明显.

Atmospheric Dry and Wet Deposition of Heavy Metals in Changchun City, China

In order to understand the characteristics of atmospheric heavy metal deposition (including wet and dry deposition) in Changchun City, 24 samples collected from 12 representative sites were taken using bulk deposition samplers in the heating and non-heating periods of 2006-2007 (about 382 days). The sampleswere analyzed for heavy metal concentration by atomic fluorescence spectrometry (AFS) and Inductively Coupled Plasma-Atomic Spectrometry (ICP-AES). The resultsshowed that the atmospheric depositions of w(As), w(Cd), w(Cr), w(Cu), w(Hg), w(Pb)and w(Zn) were 38.9, 2.24, 92.3, 76.2, 0.27, 115.2 and 462 mg/kg, respectively, which were higher than that of the topsoil (0-20 cm). It was also found that w(Cu), w(Hg), w(Pb) and w(Zn) were generallyhigher in the non-heating period than in the heating period; this could be caused by the washout effect of the rainy season. Atmospheric depositions of w(As), w(Cd), w(Cr), w(Cu), w(Hg), w(Pb) and w(Zn) were 4.79, 0.25,10.67, 8.22, 0.030, 12.31 and 48.15 mg/(m²·a), respectively, which were higher than that in North America and the NorthSea in Europe. It was also found that atmospheric depositions of w(Hg),w(Pb) and w(Zn) were generally higher in the heating periods than that in the non-heating periods. The potential impact analysis showed that the elevated atmospheric deposition of heavy metals could cause potential long-term concern on heavy metalenrichment in surface soils and potential health concerns in Changchun City, especially for Zn.