Pathways of Essential Trace Elements in Land and Coastal Sedimentary Environments: Past, Present, Future

本研究主要对镉(Cd)、钴(Co)、铬(Cr)、铜(Cu)、铁(Fe)、锰(Mn)、钼(Mo)、镍(Ni)、钒(V)和锌(Zn)这10种生物必需的微量元素进行提纯和循环分析。这些元素在不同程度上对陆地和水生植物的生长至关重要，土壤和大陆水域中单个元素的缺乏或过剩不仅可能影响其自身生物地球化学循环的功能，而且还可能影响与其耦合的其他元素的循环。总体而言，地表环境不同区块中必需微量元素的不足或过剩可能是由人为释放、剥蚀率的历史变化、气候变化、植被覆盖类型的变化等过程造成的，也可能是地质历史上陨石撞击的释放。在我们关于十个基本要素的工作的第一步，我们计划建立和完善大陆、水生和近岸海洋环境中的物质平衡和通量值。第二步是对控制这十种元素的通量的主要机制以及导致它们的循环与全球碳(C)和磷(P)循环耦合的因素进行理论分析。第三步是在碳和磷循环的一般参照系内，为这些微量元素的单独循环和耦合循环建立概念和数学模型，并进行它们的敏感性分析，这是我们和其他研究人员在早期研究中提出的。拟议工作的目标是了解全球生物圈变化中十种基本微量元素的基线图景，它们作为地质过去的环境指标的潜在意义，并获得它们在不同环境条件下的通量和储存率的上限。

The research concentrates on the refinement and analysis of the pathways and cycles of ten biologically essential trace elements: cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), vanadium (V), and zinc (Zn). These elements are to a variable extent essential to land and aquatic plant growth, and a deficiency or excess of the individual elements in soils and continental waters may affect not only the functioning of their own biogeochemical cycles, but the cycles of other elements coupled to them as well. In general, the deficiencies or excesses of the essential trace elements in different compartments of the surficial environment can be caused by such processes as anthropogenic releases, historical changes in the rates of denudation, climatic changes, changes in the types of vegetation cover, and possibly, releases from meteorite impacts in the geologic past. In the first step of our work on the ten essential elements we plan to establish and refine the mass balance and flux values in the continental, aquatic and near-shore oceanic environments. The second step is theoretical analysis of the main mechanisms that control the fluxes of the ten elements, and of the factors responsible for the coupling of their cycles to the global cycles of carbon (C) and phosphorus (P). Third step is development of conceptual and mathematical models, and their sensitivity analysis, for the individual and coupled cycles of these trace elements, within a general frame of reference of the carbon and phosphorus cycles, as has been worked out in our, and other investigators', earlier research. The goals of the proposed work are understanding of the baseline picture of the ten essential trace elements in the global biospheric change, their potential significance as environmental indicators for the geologic past, and obtainment of the upper bounds on their fluxes and storage rates under different sets of environmental conditions.