Sulfur isotope study of sulfide oxidation products: Great Marsh of Delaware and Green Lake NY

研究目标：研究将集中于描述硫化物氧化产物（聚硫化物、聚硫酸盐、硫代硫酸盐、亚硫酸盐和硫酸盐）在两个发生硫化物氧化的水系统案例研究中的硫同位素效应的表达。我们将于2009年3月、6月和8月从特拉华大沼泽和2009年夏季从绿湖（一个微生湖）收集样本。本研究的目的是对硫化物氧化产物进行分离和同位素表征。这项研究将涉及对收集这些化合物的技术进行调整，以便对四种硫同位素进行测量，并以表征和探索中间产物的同位素组成、pH值和生物活性之间的联系为目的。这项研究工作的总体目标是制定一项基于四种硫同位素的协议，对天然水生系统和沉积物中硫化物氧化的生物和非生物途径进行定量限制。这项工作植根于一个基本的前提，即产物和反应物之间以及各种氧化产物之间的小同位素效应将以不同的方式表达，这取决于硫的形态和反应途径。这项研究是我们小组和其他人正在进行的更大努力的一部分，并扩展了我们最近在硫酸盐还原剂，硫中间化合物歧化剂和生物硫化物氧化方面的实验室培养工作。拟议活动的更广泛影响：本研究的结果将准备在同行评议的期刊上发表。我们预计这项研究的结果将对地球化学系统中硫循环的其他研究产生影响，并提供一个背景，可用于告知我们对硫循环（现在和过去）中与硫化物氧化相关的同位素效应的重要性的理解。拟议的活动将包括本科生的参与，并将纳入PI的更广泛的活动。

Research Goals: Research will focus on describing the expression of sulfur isotope effects of sulfide oxidation products (polysulfides, polythionates, thiosulfate, sulfite, and sulfate) in two aqueous system case studies where sulfide oxidation occurs. We will collect samples from the Delaware Great Marsh during March, June, and August of 2009 and from Green Lake (a meromictic lake) during summer 2009. The aim of the study will be the isolation and isotopic characterization of the products of sulfide oxidation. The research will involve the adaptation of techniques for collection of these compounds so that measurements of the four sulfur isotopes can be made and with the purpose of characterizing and exploring the connections between the isotopic composition of the intermediates, pH, and biological activity. The overarching goal of this research effort is to develop a protocol based on four sulfur isotopes to place quantitative constraints on biological and abiotic pathways for sulfide oxidation in natural aquatic systems and in sediments. The work is rooted in the underlying premise that small isotope effects between products and reactants as well as between the variety of oxidation products will be expressed in different ways depending on the speciation of sulfur and the reaction pathways. This research is part of a larger effort underway by our group and others and extends our recent laboratory culture work with sulfate reducers, sulfur intermediate compound disproportionators, and biological sulfide oxidation.Broader Impacts of Proposed Activity: The results of this research will be prepared for publication in peer-reviewed journals. We anticipate that the outcomes of this research will carry implications for other studies of cycling of sulfur in geochemical systems and provide a context that can be used to inform our understanding of the significance of isotopic effects associated with sulfide oxidation in the sulfur cycle (present and past). The proposed activity will include involvement of undergraduates and will be incorporated into the broader activities of the PI.