Processes Controlling the Export of Trace Metals from Contrasting Watersheds

小行星9630277 流域对水质有重大影响。 对金属对受纳沃茨的影响的关注强调了需要关于控制从集水区输出的金属的形式和数量的因素以及极端水文事件和土地使用变化的影响的信息。我们的前提是，流中的金属的形式，浓度和负载可以用来辨别控制金属出口的流域过程。我们还假设，溶解有机碳（DOC）和悬浮颗粒物（SPM）的性质和数量从流域输运的主要地球化学因素控制金属输出。 我们的目标是确定和量化关键的地球化学和水文过程控制的形式和数量的微量金属出口流域代表不同的地质，水文，土壤类型和土地利用/覆盖。具体目标是确定（1）水文事件在控制地质和土地利用不同流域的金属输出方面的重要性;（2）控制流域内基流和事件期间金属水平、分区和产量差异的因素;（3）控制溶解相和颗粒相中金属形态的关系;控制流域关键金属运输阶段交付的因素和过程。 将比较六个相对同质流域的矩阵。（将表示流DOC中的辐射、SPM和离子强度。出口将通过同时测量排放和金属浓度来确定。将采用“超净”取样和分析方法对金属进行量化。形态将包括颗粒、胶体和“不稳定”部分，以及游离和DOC相关的“溶解”形式。我们将模拟地球化学过程调节溶解的金属浓度和负载。形态分析技术包括超滤、选择性树脂分配、电化学/伏安测量、固相分配实验、化学提取和氧化态测量。一组金属（Ag，Al，As，Be，Cd，Cr，Co，Cu，Hg，Mo，Ni，Pb，Sb，Tl，U，V，Zn）的性质将被用来探讨流域特征和控制金属输出的地球化学过程。期望为评估和预测两种金属的出口提供依据。形态将被量化和建模为地球化学因素的函数。金属出口预测能力将以流域特征和排放-地球化学关系为基础。 该提案已提交给环境地球化学和生物地球化学招标，该项目正在由地球科学（地球科学）和化学和运输系统（工程）部门联合支持。

9630277 Armstrong Watersheds have a major influence on water quality. Concern over the impacts of metals on receiving waters emphasizes the need for information on the factors controlling the forms and amounts of metals exported from watersheds and the influences of extreme hydrologic events and changes in land use. Our premise is that the forms, concentrations, and loadings of metals in streams can be used to discern the watershed processes controlling metal export. We also postulate that the nature and amounts of dissolved organic carbon (DOC) and suspended particulate matter (SPM) transported from watersheds are the main geochemical factors controlling metal export. Our goal is to identify and quantify key geochemical and hydrologic processes controlling the forms and amounts of trace metals exported from watersheds representing diverse geology, hydrology, soil type, and land use/cover. Specific objectives are to determine (1) The importance of hydrologic events in controlling metal export from watersheds of contrasting geology and land use; (2) Factors controlling within-watershed differences between base flow and event periods in metal levels, partition, and yields; (3) Relationships controlling metal speciation in dissolved and particulate phases and (4) Factors and processes controlling delivery of key metal transport phases from watersheds. A matrix of six relatively homogenous watersheds will be compared. (iradients in stream DOC, SPM, and ionic strength will be represented. Export will be determined by concurrent measurements of discharge and metal concentrations. "Ultra clean" sampling and analysis methods will be employed to quantify metals. Speciation will include particulate, colloidal, and "labile" fractions, and free and DOC-associated "dissolved" forms. We will model geochemical processes regulating dissolved metal concentrations and loadings. Speciation techniques include ultrafiltration, selective resin partitioning, electrochemical/voltammetric measurements, solid -phase partitioning experiments, chemical extractions, and oxidation state measurements. The properties of a suite of metals (Ag, Al, As, Be, Cd, Cr, Co, Cu, Hg, Mo, Ni, Pb, Sb, Tl, U, V, Zn) will be used to probe the watershed characteristics and geochemical processes controlling metal export. We expect to provide a basis for assessment and prediction of both metal export. Speciation will be quantified and modeled as a function of geochemical factors. Predictive capability for metal export will be based on watershed characteristics and discharge-geochemistry relationships. This proposal was submitted to the Environmental Geochemistry and Biogeochemistry solicitation, and the project is being jointly supported by the Divisions of Earth Sciences (Geosciences) and Chemical and Transport Systems (Engineering).