中文摘要：

采用连续提取法和原子吸收光谱法测定了西安市11个公园降尘中Cu、Pb、Zn、Ni、Cd等元素化学形态的含量,结果表明,各公园降尘中Cu和Pb含量均超过该市道路灰尘平均含量的7倍和3倍以上,有机态、铁锰氧化物态、碳酸盐态和可交换态分别为Cu总量的38%、31%、15%和13%;有机态、铁锰氧化态、碳酸盐态和交换态分别为Pb总量的35%、29%、14%和14%;除北郊的公园外,其它公园降尘中Zn的含量与道路灰尘接近,Zn以铁锰氧化态或残渣态为主;Cd含量均未超过道路灰尘中的平均含量;除城市运动公园外,其它公园降尘中Ni含量低于或接近陕西省塿土.有机结合态Cu和Pb主要与生物碎屑物质和化石燃料不完全燃烧的产物有关,铁锰氧化物结合态和交换态与制造业排放有关,碳酸盐结合态与表土扬尘有关.Ni和Cd以残渣态为主.各公园降尘中的Pb和Cu对人体健康具有潜在的威胁.

英文摘要：

Chemical speciation of Cu,Pb,Zn,Ni and Cd in dustfall samples from 11 parks in Xi′an City was extracted extracted by using the Tessier′s method and analyzed by Atomic Absorption Spectrophotometry（AAS）.The study shows that the contentrations of Cu and Pb in the dustfall samples exceed their respective averages of Cu and Pb in the urban dusts by 7 and 3 times,while the contents of Cd are of the same orders of the average of the road dusts.Contentrations of Zn in the samples collected in the northern parks are two times larger than those collected in the southern and eastern parks.The latter is the almost same order as averaged concentration of Zn in the urban dusts.Contentrations of Ni in the dustfall samples from these parks are very low and lower than or close to those in Lou Soil in Shaan′xi province.The average proportion of Cu bound to organic matter,bound to Fe-Mn oxides,bound to carbonates and exchangeable form is 38%,31%,15% and 13% respectively while the average value of Pb bound to organic matter,bound to Fe-Mn oxides,bound to carbonates and the exchangeable one is 35%,29%,14% and 14% respectively.Cu and Pb bound to organic matter could be attribated to biological wastes and production of incomplete combustion of fossil fuel,while the elements bound to Fe-Mn oxides and exchangeable ones could be considered as emissions of manufacturing industries and elements bound to carbonates are likely from aeolian dusts.Ni and Cd bound to residual speciation contribute to 65% and 85% of their total amounts respectively.The bioavailability estimated from chemical species of Cu,Pb,Zn,Ni and Cd in the dustfall samples collected in the parks indicate that only Cu and Pb can potentially threaten human health.