The Geochemistry of Rare-Earth Elements in Estuarine and Coastal Waters

本更新提案的主要重点是河口和沿海水域、沉积物和孔隙水中稀土元素的地球化学。切萨皮克湾和亚马逊河陆架将是主要的研究区域。根据P.I.S洋流的研究结果，稀土元素的通量、循环和分馏在河口带经历了重大的生物地球化学扰动。切萨皮克湾的研究结果表明，在深部盆地缺氧条件的形成过程中，轻稀土As在溶解相中得到了富集。在拟议的研究中，将在切萨皮克湾季节性缺氧盆地(水柱和沉积物)进行时间序列研究，以量化这种通量和分馏的程度和动力学。孵化实验还将跟踪稀土的成岩作用。还提议与亚马逊货架的大型多学科研究(“AmasSeds”项目)合作。亚马逊河口的季节性研究将集中于河口水域中稀土的再矿化和迁移，以及与铁和有机质的动态循环有关的沉积物中的稀土成岩作用。亚马逊河河口研究将为一个主要河流/河口系统提供亟需的稀土元素数据。

The geochemistry of rare earth elements (REE) in estuarine and coastal waters, sediments, and pore waters in the main focus of this renewal proposal. The Chesapeake Bay and Amazon River shelf will be the main study areas. Based on the P.I.'s current grant, the flux, cycling and fractionation of REE undergo major biogeochemical perturbations in the estuarine zone. Results from the Cheseapeake Bay show that light REE as being enriched in the dissolved phase during the development of anoxic conditions in the deep basins. In the proposed research, a time-series study in a Chesapeake Bay seasonally anoxic basin (water column and sediments) will be carried out to quantify the extent and kinetics of such fluxes and fractionation. Incubation experiments will also follow the diagenesis of REE. Collaboration with a large multi-disciplinary study ("AmasSeds" project) of the Amazon shelf is also proposed. A seasonal study of the Amazon estuary will focus on the remineralization and removal of REE in the estuarine waters and REE diagenesis in the sediments associated with dynamic cycling of Fe and organic matter. The Amazon River estuary study will provide much needed data on REE for a major river/estuary system.