Dissolved Metal Sulfides in Fully Oxygenated River Waters: Sources, Distribution, Composition and Bioavailability

全氧化河水中溶解的金属硫化物：来源、分布、成分和生物利用度

• 批准号: 9909278
• 负责人: Gaboury Benoit
• 金额: $ 23.18万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-15 至 2004-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9909278&HistoricalAwards=false
• 关键词: Dissolved; Metal; Sulfides; Fully; Oxygenated

9909278BenoitIntroduction: This proposal is for research to investigate complexation of heavy metals (Cu, Cd, Zn, Pb, Ag) by dissolved, reduced sulfur compounds in fully oxygenated surface waters. This project will be the first systematic investigation of dissolved reduced sulfides in oxic freshwater environments. Preliminary research suggests that metal-sulfide complexes may be the dominant form of many metals in rivers. Yet, almost nothing is known about the identity, distribution, sources, and cycling of dissolved reduced sulfur compounds and metal-sulfide complexes in this environment. While the research builds on what is known about in the marine realm, fresh waters constitute a different, and possibly more complex, biogeochemical system containing groundwater, anoxic sediments, wetlands, and pollution. Research Overview: Little is known about sulfides and their interaction with metals in oxic fresh waters. Consequently, the research strategy proceeds in two distinct stages, first, basic, then, more process oriented. In the first stage, extensive field sampling will be used to document the spatial and temporal variability of sulfides, and new analytical methods will be developed in the laboratory. In the second stage, the refined analytical techniques will be applied to samples collected from two carefully selected sites, to clarify the biogeochemical cycle of sulfides and their metal complexes in this new environment. Goals are to identify sources, elucidate composition, and better understand processes that control the behavior, transport, and fate of the dissolved reduced sulfur compounds and the complexes that they form with heavy metals in fresh oxic surface waters. The following objectives will be achieved: (1) identification of pools and pathways of interconversion of dissolved reduced sulfur in oxic fresh waters, (2) evaluation of the relative magnitude of sulfide complexation compared to other ligands, especially DOM, (3) appraisal of the nature and magnitude of dissolved reduced sulfur sources, (4) assessment of levels of total dissolved sulfides in 20 rivers and lakes covering a broad range of biogeochemical characteristics, and (5) development and refinement of analytical techniques to identify and quantify a spectrum of reduced sulfur and sulfide-metal species.Methods: Multiple analytical methods will be used to provide reliable identification and quantification of several classes of sulfur compounds, including: (1) five sulfides and individual metal-sulfide complexes (voltammetry), (2) free sulfides, precursor volatile reduced sulfur species, and dissolved acid-volatile metal sulfides (gas chromatography), (3) dissolved reduced sulfur associated with DOM (HPLC with combined polarographic/spectroscopic detection), and (4) total dissolved sulfides (preconcentration and methylene blue spectrophotometry). Clean techniques will be used at all stages of sample collection, pretreatment, and analysis to avoid contamination artifacts.Significance: Complexation can greatly reduce the reactivity of metals, thereby decreasing their bioavailability and tendency to function as micronutrients or toxins. Dissolved sulfides may dominate metal speciation in many rivers and lakes, playing a greater role than even DOM.

9909278 Benoit简介：本提案旨在研究在完全氧化的表层沃茨中溶解的还原硫化合物对重金属（Cu、Cd、Zn、Pb、Ag）的络合作用。 该项目将是第一个系统的调查溶解还原硫化物在好氧淡水环境。 初步研究表明，金属硫化物络合物可能是河流中许多金属的主要形式。 然而，几乎没有什么是已知的身份，分布，来源，并在这种环境中溶解的还原硫化合物和金属硫化物络合物的循环。 虽然这项研究建立在海洋领域的已知基础上，但淡水沃茨构成了一个不同的、可能更复杂的地球化学系统，包括地下水、缺氧沉积物、湿地和污染。研究概述：关于硫化物及其与含氧淡水沃茨中金属的相互作用知之甚少。 因此，研究策略分为两个不同的阶段，首先是基础阶段，然后是更面向过程的阶段。 在第一阶段，将使用广泛的实地取样来记录硫化物的空间和时间变异性，并将在实验室开发新的分析方法。 在第二阶段，将对从两个精心挑选的地点收集的样品应用改进的分析技术，以澄清硫化物及其金属络合物在这一新环境中的地球化学循环。 目标是确定来源，阐明组成，并更好地了解控制的行为，运输和命运的溶解还原硫化合物和配合物，他们形成的新鲜氧化表面沃茨中的重金属过程。 将实现以下目标：（1）确定好氧淡水沃茨中溶解还原硫的池和相互转化途径，（2）评价与其他配体，特别是DOM相比，硫化物络合的相对大小，（3）评价溶解还原硫源的性质和大小，（4）评估了20个河流和湖泊中的总溶解硫化物水平，涵盖了广泛的地球化学特征，以及（5）开发和改进分析技术以鉴定和量化还原硫和硫化物-金属物种的光谱。将使用多种分析方法对几类硫化合物进行可靠的鉴定和定量，包括：（1）五种硫化物和单个金属硫化物络合物（伏安法），（2）游离硫化物，前体挥发性还原硫物质，和溶解的酸挥发性金属硫化物（气相色谱法），（3）与DOM相关的溶解还原硫（HPLC结合极谱/光谱检测），和（4）总溶解硫化物（预浓缩和亚甲蓝分光光度法）。 清洁技术将用于样品采集、预处理和分析的所有阶段，以避免污染假象。意义：络合作用可以大大降低金属的反应活性，从而降低其生物利用度和作为微量营养素或毒素的倾向。 溶解的硫化物可能主导许多河流和湖泊中的金属形态，甚至比DOM发挥更大的作用。