Collaborative Research: Oxygen Isotope Tracers of Bacterial Manganese Oxidation

导致地质金属形成的反应 矿床复杂，微生物的潜在作用 在一些低温矿床的形成中， 尚未得到充分评估。 在过去的9个月里， 研究人员开发了测量18 O的技术， 锰氧化物，并使用这些测量来比较 微生物和非生物锰氧化机制。 他们 假设氧同位素组成测量 锰的氧化物可作为微生物的地质示踪剂 锰矿床的起源或作为溶解的古指示剂 氧含量，因此Eh条件，水从 形成存款的地方。 取得了进展 确定这一方法的技术可行性。 他们 将继续使用氧同位素来研究 化学和生物Mn（II）氧化，并确定是否 锰氧化物同位素特征在环境中持续存在 条件 首先，他们将评估氧气的稳定性 通过一系列的交换实验， 具有生物沉淀的不同的锰氧化物矿物， 化学上 第二，他们将确定细菌是否会破裂， 通过测量Mn（II）氧化过程中的18 O， 初始和残余反应物（O2）以及Mn氧化物 产品 第三，微生物机制的多样性将 通过培养多种Mn（ii）氧化细菌进行研究 并测定了它们的氧化物的~（18）O。 最后，关系 溶解氧浓度和18 O之间的关系 锰氧化物将在缺氧水中进行现场试验 从黑海的初步研究开始， 最后两次航行到缺氧的海洋峡湾。 这 研究对古环境具有重要意义 问题研究

The reactions leading to the formation of geological metal ore deposits are complex, and the potential role of microorganisms in the formation of some low-temperature ore deposits, while recognized, has not been fully assessed. In the past 9 months the investigators developed techniques for measuring the 18O of manganese oxides and are using these measurements to compare microbial and nonbiological manganese oxidation mechanisms. They hypothesize that measurements of the oxygen isotopic composition of Mn oxides can be used as geologic tracers for the microbial origin of Mn deposits or as a paleoindicator of the dissolved oxygen content, and there fore Eh conditions, of the water from which the deposit was formed. Progress has been made in establishing the technical feasibility of this approach. They will continue using oxygen isotopes to examine mechanisms of chemical and biological Mn(II) oxidation and determine if the isotopic signature of Mn oxides persist under environmental conditions. First, they will assess the stability of the oxygen tracer in the manganese oxide by a series of exchange experiments with different Mn oxide minerals precipitated biologically and chemically. Second, they will determine if bacteria fractionate oxygen isotopes during Mn(II) oxidation by measuring the 18O of the initial and residual reactant (O2) as well as the Mn oxide product. Third, the diversity of microbial mechanisms will be investigated by culturing a variety of Mn(ii) oxidizing bacteria and measuring the 18O of their oxides. Last, the relationship between dissolved oxygen concentration and the 18O of the manganese oxides will be tested in the field in anoxic water columns beginning with initial studies in the Black Sea and culminating in two cruises to an anoxic marine fjord. This research has significant implications for paleoenvironmental studies.