重金属元素Hg、Cd、Cu、Zn和Se在南海东岛上的时空分布特征

摘要

The biovector transport of heavy metals and other contaminants in polar areas has been widely recognized, but its role in the movement of heavy metals from marine to terrestrial ecosystems in low latitudes remains less studied. In this study, we analyzed the temporal and spatial distributions of heavy metals Hg, Cd, Cu, Zn, and Se in a tropic coral reef island, Dongdao Island, South China Sea. The results indicated that seabird droppings are the major source of elements P, Hg, Cd, Cu, Zn, and Se in the surface soils and lake sediments. The concentrations of Hg, Cd, Cu, Zn, and Se in the historical booby droppings over the past millennium were calculated and the results suggested that these heavy metals have been rapidly increasing since AD 1800, the time of the Industrial Revolution. Except Cd, the contamination levels of heavy metals in the soils and sediments of Dongdao Island are presently low; however the current 50000 red-footed boobies are generating more droppings and aggravating the heavy metal pollution on the island. These seabirds are not polluters per se; they are just inadvertent vectors of the pollutants that are released to the environment by human activities.%重金属和其他污染物迁移转化过程中的生物传输模式在极地及高纬地区已经被广泛研究，但是生物传输模式对低纬地区重金属元素从海洋向陆地转移过程中的作用目前还不是很清楚。本研究主要分析了重金属元素Hg、Cd、Cu、Zn和 Se等在南海热带珊瑚礁岛屿东岛上的时空分布。结果显示：海鸟粪是东岛表土和沉积物中元素P、Hg、Cd、Cu、Zn和Se的主要来源。同时本文还校准得到了过去千年海鸟粪中重金属元素Hg、Cd、Cu、Zn和Se的浓度变化，结果显示：海鸟粪中的重金属元素在工业革命之后均出现了快速的上升，与人类活动的加剧相对应。除了Cd之外，东岛表土和沉积物中的其他重金属元素浓度目前都相对较低，没有达到污染水平。但是，东岛上目前生活有超过50000只的红脚鲣鸟，这些鸟类会不断地从海洋中富集重金属元素，并通过鸟粪的形式输送到岛屿上。这些鸟类本身不是污染的制造者，它们只是人类排放污染物的富集和传输媒介。