城市地表灰尘_降雨径流系统重金属生物有效性研究

城市地表灰尘2降雨径流系统重金属生物有效性研究

常静

1,2

,刘敏

13

,李先华2,林啸1,王丽丽1,高磊

1

(11华东师范大学资源与环境科学学院,教育部地理信息科学重点实验室,上海 200062;21上海大学通信与信息工程学院,

遥感与空间信息科学研究中心,上海 200072)

摘要:以上海中心城区为例,定点采集地表灰尘、径流悬浮物、雨水口和河流沉积物,探讨重金属在地表灰尘2降雨径流系统中的环境行为及其生物有效性变化.研究表明,研究区域地表灰尘重金属浓度高于上海土壤背景值,其中Zn 、Pb 、Cd 和Cu 高出5~7倍,Cr 和Ni 高出2倍,径流非点源污染Pb 、Cr 和Ni 贡献较大,Cd 、Cu 和Zn 污染程度较轻.多介质赋存形态研究表明,重金属生物有效性依次为Zn >Ni >Cd >Cu >Pb >Cr.其中Cr 、Zn 和Cu 在4种介质中分别以残渣态、碳酸盐态和有机态为主;Ni 地表灰尘以残渣态为主,其它3种介质以碳酸盐态为主;Cd 地表灰尘以有机态为主,径流悬浮物以非稳定形态为主;Pb 在迁移过程中主导形态由铁锰结合态变为有机态.非稳定形态(F1+F2)在径流悬浮物组分中占有最高比例,6种重金属迁移比率平均值为1174,说明从地表灰尘到径流颗粒物,重金属生物有效性明显升高,径流水体毒性和潜在生态效应值得关注;雨水口和河流沉积物残渣态含量较高,成为重金属在城市地表环境迁移的蓄积库.关键词:重金属;地表灰尘2降雨径流系统;多介质环境;生物有效性

中图分类号:X502 文献标识码:A 文章编号:025023301(2009)0822241207

收稿日期:2008208216;修订日期:2008210215

基金项目:国家自然科学基金重点项目(40730526)

作者简介:常静(1980~),女,博士,主要研究方向为城市环境与多界

面过程,E 2mail :cj1221@http://m.wendangku.net/doc/360fbbcd05087632311212be.html

3通讯联系人,E 2mail :m liu @http://m.wendangku.net/doc/360fbbcd05087632311212be.html

Bioavailability of H eavy Metals in U rban Surface Dust and R ainfall 2Runoff System

CH ANGJing

1,2

,LI U Min 1,LI X ian 2hua 2,LI N X iao 1,W ANGLi 2li 1,G AO Lei

1

(1.K ey Laboratory of G eographic In formation Science of M inistry of Education ,School of Res ources and Environment Science ,East China N ormal University ,Shanghai 200062,China ;2.Research Center of Rem ote Sensing and S patial In formation Science ,School of C ommunication and In formation Engineering ,Shanghai University ,Shanghai 200072,China )

Abstract :A sequential digest was used to examine the speciation of particulate 2ass ociated heavy metals in multi 2media environment of sur face dust and rain fall 2runoff system.Within the Shanghai central district ,different environment medium in four sites were sam pled including street dust ,runoff suspended particles ,gully pot sediment and river sediment during April 2006.The result shows that in the study area ,heavy metal concentrations of sur face dusts are significantly higher than the Shanghai s oil background values and the nonpoint runoff pollution of Pb ,Cr and Ni are serious while Cd ,Cu and Zn pollution degree relatively light.In the multi 2media transport process ,the order of heavy metal bioavailability is Zn >Ni >Cd >Cu >Pb >Cr.F or Cr ,Zn and Cu ,the dominated chemical forms of the four different environmental media remain the same phase of residual ,carbonates and organic fractions respectively.F or Ni ,the main fraction of sur face dust is ass ociated with residual form ,while the other three media become ass ociated with carbonate fractions.F or Cd ,the sur face dust is mainly ass ociated with carbonates ,while runoff particles mainly with labile fractions.The dominated chemical form of Pb als o changes from Fe ΠMn oxides phase to organic phase.The runoff particles contain the highest percentage of the labile fraction (F1+F2),and the mean value of transporting ratio of the runoff suspended particles equals to 1174,indicating that in urban runoff water ,the high bioavailability of the heavy metals and the potential toxicity effect deserves our attention greatly.In gutter inlet and rivers deposit com ponents ,the low percentages of the labile fraction and the higher content of residual fraction reduce the environmental risk of the heavy metals and act as the sink of these elements.K ey w ords :heavy metal ;sur face dust and rain fall 2runoff system ;multi 2media environment ;bioavailability

城市非点源污染指降雨径流淋洗与冲刷大气和汇水面各种污染物引起的受纳水体污染,是城市水环境污染的重要因素.城市地表环境是多介质交互作用、多界面汇集的复杂系统,污染物在各自然要素中的分布具有多源性和不均匀性,从物质迁移的系统角度认识非点源污染物在各个环节的分配特征有

着重要意义.国外不少研究做出了有益的尝试[1~10]

,

Charlesw orth 等[1~3]

以英国考文垂为例,采集“地表灰尘2雨水口沉积物2河流沉积物”,研究了重金属迁移

转化特征;Duzg oren 等[4,5]

研究了广州“地表灰尘2交通隧道灰尘2雨水口沉积物”重金属分布特征与来

源.目前国内关于单一介质如地表灰尘、降雨径流、

河流沉积物等环境介质的重金属污染研究较多[11~19],但有关重金属物质迁移的整体性研究较少.鉴于此,本实验从物质源汇迁移的角度出发,在建立污染物城市地表环境系统循环概念模式的基础上,定点采集不同环境介质样品,研究重金属在“地表灰尘2降雨径流”系统迁移过程中生物有效性的变

第30卷第8期2009年8月

环 境 科 学E NVIRONME NT A L SCIE NCE

V ol.30,N o.8Aug.,2009

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