南沙珊瑚礁生态系中元素的垂直转移途径

PATHS OF ELEMENT VERTICAL TRANSPORT IN THE NANSHA CORAL REEF ECOSYSTEM, SOUTH CHINA SEA

于1993年和1994年用沉积物捕捉器采集南沙永暑礁和诸碧礁内的沉降颗粒物，用中干活化法分析兀素的含量并计算通量，通过对生源要素的统计相关分析、垂直沉降颗粒物中的元素比、非生源要素在泻湖中的停留时间的探讨，研究了南沙珊瑚礁生态系中元素的垂直转移途径。结果表明，在南沙珊瑚礁泻湖中元素的停留时间较海水中短，元素的循环速率高，且尤以与生物作用有关的元素为甚；颗粒物中非生源要素的垂直转移主要是通过生物过程完成的，其转移量可达80％以上，表明珊瑚礁生态系中非生源元素与生源元素有相似的垂直转移机制。

Settling particulates were sampled by sediment traps deployed in the lagoons of Zhubiand Yongshu reefs in 1993 and 1994, Nansha Islands waters, the South China Sea. The elementriconcentrations in particles were determined with the method of neutron active analysis. Statisticalrelahonship between biogenic and abiogenjc elements, elemental rahos in settling partjcles and theresidence hme of abiogenic element-S in coral reef lagoons show that=1) most of abiogenic elementsare direchy propohional to biogenic elements (such as organic carbon, nitrogen or phosphorus) interms of concentrations or vetucal fluxes of settling par-ticles, the correlation coefficientS being morethan | 0.85J; 2) a number of e1emental rahos can be used to illustrate the origin of material e. g.by using the ratios of Co / La, the origin of settling panicles can be studied, the authigenic biogenicparts accounts for 95.7% and 94.3%, during the chose 93- 5 and 94 4 in Zhubi reef lagoon respectively, and 83.7% during the cruise 1993- 1994 in Yongshu reef lagoon, indiating that the vertical transport magnitude by biological process accounts for more than 8O% of abiogenic elements,3) the residence time was smaller in coral reef lagoons than in seawaters, the residence time of Zr,Ti, Fe, Al, La, Ce, Nd, Sm, Eu, Tb, Yb, Lu in Nansha cora1 reef lagoons are from several daysto hundred days, and from severa1 years to thousands years for the other abiogenic elements, as aresult, the abiogenic element cycling rates are high in lagoons.According to the above results, the vertical transport mechanism of abiogenic elements is thesame as biogenic elen1ents.