三峽庫區消落帶土壤重金屬含量特征及污染評價

摘 要：以三峽庫區蓄水位從175m回落至163m后的云陽段消落帶土壤為研究對象，進行重金屬Cu、Zn、Pb、Cd和Cr的含量與剖面分布特征及評價研究。結果表明：消落帶土壤Cu、Zn、Pb、Cd和Cr的含量分別為58.09mg/kg、108.93mg/kg、15.18mg/kg、0.46mg/kg和71.81mg/kg。重金屬剖面分布特征呈規律性變化：0～10cm土層Cu、Cr和Zn含量高于10～20cm土層，而在干濕交替處Zn、Cr含量卻表現為0～10cm土層低于10～20cm土層；Pb和Cd剖面分布特征均呈現出0～10cm土層含量低于10～20cm土層，而在干濕交替處呈相反趨勢。研究區不受Pb污染，而受Cd、Cu、Zn和Cr不同程度污染，尤以Cd污染最嚴重，甚至超出三峽庫區土壤背景值3倍以上。

關鍵詞：三峽庫區；消落帶；土壤重金屬含量；分布特征；污染評價

中圖分類號 X53 文獻標識碼 A 文章編號 1007-7731（2013）15-16-03

The Characteristics and Assessment of Heavy Metal Concentrations in Fluctuation Zone of Three Gorges Reservoir Area

Mo Fuxiao et al.

（School of River and Ocean Engineering，Chongqing Jiaotong University，Chongqing 400074，China）

Abstract：This study was devoted to fluctuation zone of Three Gorges reservoir area in Yunyang and the concentrations of Cu，Zn，Pb，Cd and Cr were determined which ranged from 175m to 163m in water-level-fluctuating zone soils. The result indicated that the total concentrations of Cu，Zn，Pb，Cd and Cr were 58.09mg/kg，108.93mg/kg，15.18mg/kg，0.46mg/kg and 71.81mg/kg，respectively. The profile distribution characteristics of heavy metal content changed regularly：the content of Cu，Cr and Zn in surface soil is higher than that of in the deep soil，but the content of Cr and Zn in surface soil is lower than that of in the deep soil at the dry-wet alternation；Content characteristics of Pb and Cd was the same，emerged as the surface is less than deep and the surface is more than deep at the dry-wet alternation. The study area was contaminated by Cd，Cu，Zn and Cr in varying degrees，but far from the Pb pollution；however pollution of Cd was particularly serious，even beyond the background value more than three times.

Key words：Three Gorges reservoir area；Fluctuation zone；Heavy metal in soil；Characteristic；Pollution assessment

消落帶是因水庫調度引起的水位漲落而于庫區周圍形成的一段特殊區域。在人工調控下，三峽庫區水位的周期性漲落會在兩岸形成垂直落差30m、面積約348.9km2的消落帶。消落帶是水生生態系統與陸生生態系統的過渡地段，其土壤理化性質及重金屬含量嚴重影響庫區水質和周圍動植物的生命活動。消落帶土壤重金屬污染具有隱蔽性強、形態多變、無法被生物降解、容易在生物體內累積等特點[1]，并能通過食物鏈在生物體內不斷富集，最終將嚴重危害人類的健康[2-3]。筆者對三峽庫區消落帶云陽段不同高程、不同采樣深度土壤剖面的重金屬Cu、Zn、Pb、Cd和Cr含量與分布特征進行分析和研究，進一步評價該區土壤重金屬污染情況，以期為庫區生態環境治理和農田可持續發展奠定理論依據。

1 材料與方法

1.1 土樣采集及調查 2012年4月，在重慶市云陽縣境內沿長江主要次級河流的三峽庫區消落帶的荒地采集土樣。……