长春市典型高架公路大气环境颗粒物中重金属污染特征

于2014年4—11月对长春市典型高架公路大气颗粒物PM_(2.5)和PM_(10)进行采样,对颗粒物中主要重金属元素的浓度进行了分析,并采用变异系数法、地积累指数法和富集因子法对大气颗粒物重金属污染情况进行评价.研究表明,道路施工期间,PM_(2.5)和PM_(10)中重金属的浓度普遍低于道路运行通车后的浓度,而采暖期重金属的浓度又高于非采暖期的浓度.重金属元素在PM_(2.5)中的含量占PM_(10)中总含量的比例均超过50%,说明颗粒物越细越容易富集重金属.Zn、Fe和Mn的变异系数较小,说明来源稳定,自然源占主导地位.富集因子法表明,Zn的富集程度极强,Mn无富集.Cr和Cd的变异系数较大,受人为活动干扰严重,在道路施工期间二者富集程度较轻,道路通行加之采暖后富集程度加强,主要来源为汽油和煤的燃烧.Pb、Cu和Ni的变异系数在0.56~0.76之间,有一定的人为干扰,Pb和Ni在高架公路施工期富集程度较轻,道路运行及取暖期富集程度显著,主要来源是交通源;Cu富集程度强,主要来源可能是油燃烧、建筑扬尘.

Pollution characteristics of heavy metals in atmospheric particulates from typical elevated highway in Changchun City

Atmospheric particulate PM_2.5 and PM₁₀ were sampled from a typical elevated highway in Changchun City from April to November 2014. Concentrations of the main heavy metal elements in PM_2.5 and PM₁₀ were analyzed. The pollution condition of these heavy metals in the particulates was evaluated by variation coefficient method, geo accumulation index and enrichment factor method. The results showed that heavy metal concentrations in PM_2.5 and PM₁₀ during elevated highway construction were generally lower than the concentrations during highway opened to traffic. Heavy metal concentrations during heating period were higher than the concentrations during non-heating period. The content of heavy metal element in PM_2.5 accounted for more than 50% of the total content in PM₁₀, which indicated that heavy metals were easy to enrich on the fine particulates. The variation coefficients of Zn, Fe and Mn were smaller with stable source and the natural source was dominant. Enrichment factor method showed that Zn enrichment degree was extremely significant and Mn had no enrichment. The variation coefficients of Cr and Cd were greater, indicating that these elements were seriously disturbed by anthropogenic activities. The enrichment degree of Cr and Cd was lighter during road construction, however, it was strengthened during highway traffic and heating period. The major source categories of Cr and Cd were the gasoline and coal combustion. Variation coefficients of Pb, Cu and Ni were from 0.56 to 0.76 with a certain human disturbance. The enrichment degree of Pb and Ni during highway construction period was lighter and enrichment was significant during road traffic and heating period, which indicated that these two elements originated mainly from traffic sources. Cu enrichment degree was significant and the main source was likely to be oil combustion and construction dust.