南沙群岛珊瑚礁生态系中稀士元素的垂直转移过程研究

海洋沉积物中稀土元素的分布、转移行为已有许多报道。地球环境中稀土元素的行为是当今地学研究的热门课题,稀土元素的分布特性和转移行为研究与环境有极大的相关性,通过研究环境中稀土元素的转移行为就可了解环境演变的信息,所以海洋环境中稀土元素的研究具有重要的意义(Fleet,1984; Piper,1974; Schijf et al.1995;赵一阳等，1994;王中刚等,1989;张丽洁等,1995)。海洋中颗粒物质垂直转移过程研究对研究海洋在全球变化(特别是全球气候变化)中有重要意义,但目前的研究仅集中于以碳为核心的生源要素和某些微量元素(宋金明等,1996;宋金明,1997),至今稀土元素在海水中垂直转移过程研究尚未见报道。珊瑚礁生态系是最重要的海洋生态系之一,研究珊瑚礁生态系中稀土元素的垂直通量,即热带海域稀土元素在海水中垂直转移过程,继而椎测对全球气候变化的影响,为研究海洋在全球气候变化中的作用提供了新课题。 本文首次报道用沉积物捕捉器(ST)收集南沙珊瑚礁潟湖中颗粒物质,研究稀土元素的垂直通量和不同形态稀土的垂直通量,以及稀土元素垂直转移的控制因素。

VERTICAL TRANSFORMATION PROCESSES OF RARE EARTH ELEMENTS IN THE CORAL REEF ECOSYSTEM OF NANSHA ISLANDS WATERS, SOUTH CHINA SEA

The vertical fluxes, vertical transformation forms and the controlling factors of rare earth elements in the coral reef ecosystem of Nansha Islands waters, South China Sea, were studied in 1993 to 1994 by using sediment trap and neutron active analysis. The main results were as follows: La has the highest vertical flux, accounting for 90% of the total flux of rare earth elements. The second is Nd or Ce. The vertical fluxes of rare earth elements are higher in Yongshu reef than in Zhubi reef. The transformations of light rare earth elements is easier than those of heavy rare earth elements. The main transformation forms of rare earth elements in Yongshu reef are carbonate, exchangeable-ion and Fe-Mn oxides,accounting for 73%, 11.3% and 10.3%, respectively. Organic matter+Sulfide and silicate amounted to 2.4% and 2. 37%, respectively. Carbonate and organic matter+sulfide are the main vertical removal forms of light rare earth elements. Fe-Mn oxides and silicate are the main vertical removal forms of heavy rare earth elements. Biogeochemical Process, distribution of biocoenose and geographic location of coral reef etc. are the main controlling factors of vertical transformation of rare earth elements in the coral reef ecosystem of Nansha Islands waters, South China Sea.