【摘要】 地球化学家通常用A l对其它重金属进行归一化以校正沉积物来源、粒度、矿物组成等方面的影响,因此现代海洋沉积物样品中A l、Ti含量的结果主要用于定量描述陆源输送的贡献。近期研究结果发现,在受陆源物质输送影响较小,沉降颗粒主要以生源颗粒物为主的赤道大洋区,沉积物中出现明显的“过剩铝”信号,“过剩铝”约占沉积物中总铝含量的50%。因此,用沉积物中A l的含量来估算陆源碎屑的比例会导致过高的结果,建议用Ti、Sc作为参比元素校正陆源物质的影响。沉积物中的A l/Ti比值可用来示踪水体中颗粒物的沉降通量和初级生产的改变。综述了近期以A l/Ti比值这种新的地球化学示踪剂反演古生产力的最新研究进展,提出了在我国陆架边缘海开展此项工作可能存在的问题与挑战。更多还原

【Abstract】 Accordingly,Aluminum is always used as the normalized element by geochemists to minimize the natural variability of heavy metals in the sediments,which includes the effect of sedimentary origin,grainsize and mineral composition.Thus,measurements of Al in marine sediments are always used to determine quantitatively the amount of terrestrial material in a given sample.However,this normalized method met problems in the open ocean.The results indicate that there exists significant non-detritus Al(excess Al) component in the sediments of open ocean near the equator,where the sediments were composed mainly by biogenic compositions other than terrestrial matter.Excess Al can account for nearly 50% of the total Al in the sediments.Therefore,using Al abundance to estimate the terrestrial matter abundance in marine sediments,which is generally used in the previous studies,may give over-estimated results.It is suggested that Ti and Sc be used as normalized elements to minimize the effects of terrestrial matter in the open oceans.The results show that Al/Ti ratio can be used to reconstruct the biogenic sediment accumulation and hence productivity through time in the biogenic regimes where terrestrial input is only slight.The newest progresses in the geochemical proxy of Al/Ti ratio to reconstruct the paleoproductivity are presented.Problems may appear when this geochemical proxy is applied in the coastal and shelf regions,which is also discussed in the paper.更多还原