兰州市某城区冬夏季大气颗粒物及重金属的污染特征

在2010年7月与2011年1月,对兰州市西固区、榆中县的大气颗粒物(TSP、PM10、PM2.5)进行了采集,并对颗粒物浓度及不同粒径颗粒物上的重金属(Cd、Cr、Cu、Pb、Ni、Zn)含量进行了分析.结果显示,夏季TSP的浓度均值均未超过国家标准值,而冬季只有研究区均值超过国家标准值,超标倍数为0.36倍;研究区PM10冬、夏季浓度均值皆高于国家标准值,超标倍数分别为1.18和0.19倍,而在对照区只有冬季均值超过了标准值,超标倍数为0.05倍;冬季PM2.5的浓度均值在研究区和对照区均超过参考标准值,超标倍数分别为1.94倍和1.0倍,而夏季浓度均值只在研究区超标,超标倍数为0.31倍.颗粒物TSP、PM10及PM2.5的浓度均值呈现的整体特点为冬季高于夏季,且研究区显著高于对照区.应用潜在生态风险指数法评价显示,大气颗粒物中重金属元素的生态危害顺序为:Cd>Cu>Ni>Zn>Pb>Cr,其中Cd的潜在生态危害程度为极强;多种重金属联合的生态风险指数显示,TSP、PM10、PM2.5的重金属生态风险程度均为极强,其中PM2.5的潜在生态风险指数最高.

Analysis of atmospheric particles and heavy metals character at the area of Lanzhou City in summer and winter

The TSP,PM10,PM2.5 particles were sampled at Xi Gu Area and Yu Zhong County(in Lanzhou City) in July 2010 and January 2011.The contents of TSP,PM10,PM2.5 particles and heavy metals(Cd,Cr,Cu,Pb,Ni,Zn) in TSP,PM10,PM2.5 particles were analyzed.The result indicated that the average concentration of TSP in winter in research area was 0.36 times higher than national standard level-II,while concentration was lower in summer.In research area,the average concentration of PM10 both in winter and summer increased 1.18-fold and 0.19-fold respectively,in comparison with that of national standard level-II.In comparison area,the average concentration of PM10 in winter was 0.05 times higher than national standard.Compared with American daily mean value standard,the average concentration of PM2.5 in research area and in comparison area in winter increased 1.94-fold and 1.0-fold,while the value increased 0.31-fold in research area in summer.In condusion,average concentration of TSP,PM10,PM2.5 in winter was higher than that in summer,and the concentration in research area was higher than that in comparison area.An order of potential ecological risk inedx of heavy metals in atmospheric partiles was Cd>Cu>Ni>Zn>Pb>Cr,in which the potential ecological risk degree of Cd reached terribly strong.While the potential ecological risk index of TSP,PM10,PM2.5 were all reached the terribly strong level,in which the PM2.5’s potential ecological risk index was highest.