昆明市街道灰尘重金属污染及潜在生态风险评价

Heavy Metal Pollution and the Ecological Risk Assessment of Urban Street Dust in Kunming

利用X-Ray荧光光谱仪对昆明市街道灰尘的Cu、Zn、Pb、As、Cr和Ni等元素进行了分析,讨论了街道灰尘中重金属含量的水平和空间分布特征;采用潜在生态危害指数法对灰尘中重金属的潜在生态风险进行了评价。结果表明:昆明市街道灰尘中重金属Cu、Zn、Pb、As、Cr和Ni的平均含量分别为166.6、316.53、97.49、20.56、79.41和21.45 mg/kg,与全国土壤背景值相比有较大积累,其中Cu、Zn、Pb和As都达到相对富集类,污染程度较重;重金属元素在旱季有明显积累趋势,雨季相对降低;重金属在工业区含量最高,其次为交通区,其中内城重金属污染源主要来自于汽车交通污染,外城来源于工业污染。灰尘中重金属潜在生态风险处于轻微生态危害水平,且潜在生态风险系数大小顺序为Cu>Zn>As>Pb>Cr>Ni,其中Cu是最主要的生态风险因子。

The concentrations of Cu,Zn,Pb,As,Cr and Ni in urban street dust collected from Kunming were analyzed by using X-Ray fluorescence spectrometry.Spatial technique was applied to study the content level and the spatial distribution characteristics of heavy metal pollution in street dust of Kunming.The ecological risks of heavy metals in street dust were assessed with the potential ecological risk index method.The results show that the average concentrations of Cu,Zn,Pb,As,Cr and Ni in the street dust in Kunming were 166.6,316.53,97.49,20.56,79.41 and 21.45mg·kg-1,respectively,much higher than the background concentrations in soil in China,in which Cu,Zn,Pb and As contributed to pollution largely,whose concentrations had reached a relative enrichment level.Accumulation of heavy metals in dry season was significantly higher than that in rainy season.The highest content of heavy metals existed in the industrial areas,and the second in traffic areas.Heavy metals mainly came from traffic pollution in urban street dust and from industrial pollution in suburbs.The potential ecological risk of heavy metals in the street dust of Kunming had reached a higher level.The order of potential ecological risk indexes of heavy metals was Cu Zn As Pb Cr Ni,in which Cu was the most important ecological risk factor.