城市不同功能区地表灰尘重金属时空动态变化

Dynamic distribution variation of heavy metal contents in the outdoor settling dusts in different functional urban areas

以贵阳市交通区-城市广场-文教区-住宅区-城中村地表灰尘为研究对象,对不同月份地表灰尘进行跟踪采样分析,研究不同功能区地表灰尘重金属质量比的时空变化特征,并通过内梅罗指数法对灰尘重金属累积程度进行评价。结果表明:1)As、Cd和Pb月质量比最低值出现在6—7月,而Cu、Ni和Zn月质量比最低值出现在11月上旬,各元素月质量比最高值出现的月份不尽相同,但以11—12月为主;2)春冬季地表灰尘重金属质量比高于夏秋季;3)灰尘中Ni、Zn质量比随时间和区域的变化最小,As、Cd、Cu和Pb质量比随时间和区域的变化较大,这4种元素在城市广场累积最重;4)人类活动是影响地表灰尘重金属迁移和累积的重要因素之一,温度、降雨、街道形状和地理位置也是影响地表灰尘重金属含量的因素。

The present paper is engaged in an investigation of the dy- namic distribution variation of the heavy metal contents in the outdoor settling dusts in different functional urlsan areas by taking Guiyang, Guizhou, as a study sample. As is known, dust is the most pervasive and harmful pollutant for the urban environment, whose exposure to human beings can bring about harmful adverse effects to human health. Though many studies have been done over the heavy metal pollution in the urban environmental dust in China based on the sin- gle-time sampling, it remains relatively weak on the research over the variation characteristics of heavy metals in dust. Coming from the aforementioned need, we are going to devote our work to the dynamic variation study of the heavy metal concentrations in the outdoor dust from March through December in the same year. Thus, for our re- search purpose, we have collected dust samples from the five districts of Guiyang City, that is, the Traffic Areas（TA）; the City Square （CS）; School Quarters Area（SA）; the Residential Areas（RA） and the Urban Village（UV） areas. The results of our investigation can be stated as follows： the concentrations of Cd, Cu, Ni, Pb, and Zn have been analyzed by the ICP - MS, and that of As determined by using the atomic fluorescence spectrometry whereas we have used Ne- mero pollution index to evaluate the accumulation level of the heavy metals. The results of our analysis can be shown as follows ： （ 1 ） The minimum values of As, Cd and Pb tend to appear in June and July, while the minimal values of Cu, Ni and Zn pollution tends to appear in early November. Though the maximum values of heavy metal pol- lution appear in different months, the serious pollution tends to appear mainly in November and December. （2） Heavy metal pollutants turn to appear more serious in the outdoor settled dust in spring and winter than in summer and autumn. （3） Though the temporal and spatial variation prove to have minor influence on the concentrations of Ni and Zn, strong effects come from the concentrations of As, Cd, Cu and Pb, which tend to pile up most heavily in the urban squares. （4） Human activities prove to be an important factor affecting the migra- tion processes and the accumulation of heavy metals in the outdoor settled dust. In addition, temperature, rainfall, street terrain and the location also prove to affect the concentrations on heavy metal dust spread and its dynamics. The results of our investigation demonstrate that the accumulation of heavy metals in the urban squares turns to be heavier than in other functional areas, which makes it necessary to study further the pollution sources of heavy metals in urban square dusts and the urban square pollution features including the congrega- tion and accumulation degree with the specific features in terms of the personnel structure.