The Distribution Of Heavy Metals On Different Spatial Scale For Urban Street Dust

Urban dust studies is an important part of urban environment, the chemical speciation of the dust, heavy metals, content characteristics, spatial distribution and pollution assessment are the most popular topic。At present, the spatial distribution of heavy metals in urban dust focus on cities, and mainly research its content and affecting factors onthe "punctuation""linear""surfaceshape". And many results emphasize the absolute impact of human activities for heavy metal content and distribution of urban dust, especially the location of traffic and industrial activities have prominent role.Selecting the main city in Jinhua, the urban and rural in Jinhua, Zhejiang Province, to research the characteristics and distribution of heavy metal in surface dust in different spatial scales, the natural geographic environmental factors and impact of human activities for its showing some kind of spatial distribution.That can be provide a reference for construction of urban ecological environment,urban and rural planning, regional development, the protection of human health. Through qualitative, quantitative and spatial analysis of combining research methods, the following conclusions: Fist, The characteristics and distribution of heavy metal in different spatial scales(1) In the main city, Cumulative index of heavy metals were Zn> Pb> Co> Cu> Cr> Ni. In urban and rurals in Jinhua, Cumulative index of heavy metals were Co>Zn>Cu>Pb>Cr>Ni.In zhejiang,Cumulative index of heavy metals were Cu>Zn>Pb>Cr>Co>Ni.In different areas,the geoaccumulation index of Pb, Zn, Cu, Cr, Ni gradually increased from urban and rural area,the main city toZhejiang province scale. The Co were opposite.(2) From main city to the urban and rural in Jinhua, except Co elements, spatial variability reduced as the expansion of the study area.Especially Cu, Cr was reduced from the main city,urban and rural area to Zhejiang province.(3) The content of heavy metal in the main city in Jinhua reduced gradually from the high value area in the center to the surrounding in the space. In urban and rurals in Jinhua, the content of heavy metals in the main city were higher than townshiple, Pb、Zn、Cu、Cr and Ni showed that towns in south-west of Jinlan reservoir were higher, towns in north-west were lower.Co performance contrast. In zhejiang, for heavy metal content,the Southeast and northeast are high, northeast and southwest are low, meanwhile the content increase from the mainland to the coastal gradually. Second, the correlation changes of heavy metals in surface dustin different regions of the scale(1) At the0.01level, the correlation among the Pb, Cu,Zn and Ni in main of Jinhua City are greater than0.8, the Ni-Cr, Zn-Pb, Ni-Pb, Ni-Cu, the Ni-Zn in the township are more significant, R>0.5, Zhejiang Province, th higher levels of the elements is Ni and Zn, Pb whith Cu, Zn, Ni correlation reduce compared with Jinhua City. The level of correlation of Cr at the same level compared with Jinhua City, but the Co in the degree of correlation increased slightly.(2) From main city to the urban and rural in Jinhua, the correlation of heavy metals showed a decreasing trend,especially the correlation of Pb, Cu, Zn and Ni affected by human activities and the industrial and transport activities own a decreasing trend as the regional scale expansion,, Cr has a low content and relatively stable whith ther heavy metals. The correlation of Co has an increasing trend from main city to Zhejiang.Third.Economic and social activities in different scales(1) Human activity is the main factors for content and distribution of heavy metals in the urban and rural, and the degree of the role of the main urban areas than rural area. Characteristics and distribution of the dust heavy metal content of the main city is basically by human activities and scope of the decision, the greatest influence is the transport and industrial metallurgical industry, followed by food and beverage, printing, medical and health care. In rural areas the accumulated dust of heavy metals are transport, rural energy structure, solid garbage burning and villages alloy industry.(2) In Zhejiang Province,except Co, the other all had significantly related with the population density, industrial output, the output value of tertiary industry, motor vehicles for civilian ownership and other economic and social development indicators,There are two economic and social factors,one was the city’s industrial development, transport and energy consumption, the other was urban population and urban area.Forth. The impact of the regional natural geographical environment(1)Excellent eco village geomorphological and high forest coverage rate were one natural factors for distribution of the heavy metals in Jinhua.(2) Terrain features and the monsoon is an important factor for the migrate、 spread and dilution for heavy metal in Zhejiang province.(3) Local soil background also a important roles. Except Co, the heavy metal elements are consistent with the changes in local soil background.The correlation between heavy metals and soil background is increasing as expansion of the scale of the study area.