Expanded Calibrations and Standardization of the Phosphate Oxygen Isotope System

为了更好地分析和解释磷酸盐氧同位素比值值，从目前正在研究的范围广泛且不断扩大的自然系统和未来计划研究的更极端的环境中获得，在这里，我们提出了一系列全面的受控实验室校准和标准化的磷酸盐？水o同位素系统，涵盖与自然系统和栖息在这些系统中的微生物（如嗜热菌、嗜酸菌）相关的温度、pH值和离子强度范围。拟议研究的主要目标是：(1)改进和扩展po4 -水O同位素分馏的校准，以涵盖与目前正在调查的广泛自然系统和微生物（例如，极端微生物，古细菌）相关的环境条件（例如，温度，pH）；(2)直接比较不同已发表的溶解无机PO4 （DIP）氧同位素组成分析方法；3)准备一套磷酸银氧同位素分析标准，以补充2002年准备的逐渐减少的库存，这些标准将分发给各实验室和科学界成员，用于实验室间比较和各种同位素分析方法的标准化。此外，我们建议跨主要生命领域（细菌，古细菌）和与常见代谢（例如BSR，甲烷生成）和地质生物学重要群体（微生物席形成的缺氧光养生物-紫色和绿色硫细菌；铁氧化和铁还原细菌）相关的磷酸盐-水o同位素系统研究。拟议研究的一般方法将是进行受控的实验室实验，以校准PO4和水之间的氧同位素分馏作为温度、pH和离子强度的函数，并根据先前发表的和完善的实验方案合成新的磷酸银O同位素分析标准。智力优势：拟议的研究将主要解决磷酸盐氧同位素系统校准方面的缺陷，以及社区对磷酸盐氧同位素标准和最近开发的分析方法的标准化/比较日益增长的需求。这些研究对于氧同位素方法在低温地球化学中的许多正在进行和未来的应用以及P的地球生物学研究至关重要。研究应用将受益于拟议研究的结果，包括研究PO4 d18OP生物特征和P在环境和样品中的生物地球化学循环，范围从海洋水柱、土壤、沉积物、热液系统和污染含水层到海底深层生物圈；以及细菌对PO4代谢的一般研究，特别是古细菌对P的代谢尚未进行详细研究。更广泛的影响：作为拟议研究的一部分，将合成PO4的O同位素分析的磷酸银标准将通过耶鲁大学稳定同位素分析中心提供给更广泛的科学界。同时，对天然水体中溶解无机PO4分析方法的比较也将有利于当前和未来利用d18OP进行磷循环研究的研究人员。拟议中的研究将培养两名女性博士后助理：Lisa Stout博士和Saejung Chang博士，以及参与耶鲁皮博迪博物馆赞助的K-12教育项目的本科生暑期实习生和大学预科学生，共同赞助人Ruth Blake是该博物馆的定期贡献者。拟议研究的结果将纳入耶鲁大学PI Blake和博士后Lisa Stout教授的地球微生物学研究生和本科课程；以及在国内和国际会议上的公开演讲。这项研究也将用于通过耶鲁皮博迪博物馆的进化项目赞助的K-12教师培训实习。

To better facilitate analyses and interpretations of phosphate oxygen isotope ratio values obtained from the wide and growing range of natural systems currently under study and more extreme environments planned for future study, here we propose a series of comprehensive controlled laboratory calibrations and standardizations of the phosphate?water O-isotope system covering the range of temperature, pH and ionic strength relevant to natural systems and the microorganisms that inhabit these systems (e.g., thermophiles, acidophiles). The primary objectives of the proposed research are to:(1) Refine and extend calibrations of PO4-water O isotope fractionations to encompass environmental conditions (e.g., temperature, pH) relevant to the wide range of natural systems and microorganisms (e.g., extremophiles, archaea) currently under investigation;(2) Make direct comparisons among different published methods for analysis of the oxygen isotope composition of dissolved inorganic PO4 (DIP); and3) Prepare a suite of silver phosphate standards for PO4 oxygen isotope analysis to replenish waning stocks prepared in 2002 that will be distributed to various laboratories and members of the scientific community for inter-laboratory comparisons and standardization of various methods of isotopic analysis.Furthermore, we propose investigations of phosphate-water O-isotope systematics across major domains of life (bacteria, archaea) and associated with common metabolisms (e.g., BSR,methanogenesis) and geobiologically important groups (microbial mat-forming anoxygenicphototrophs--purple and green sulfur bacteria; iron-oxidizing and iron-reducing bacteria). The general approach to proposed research will be to conduct controlled laboratory experiments to calibrate oxygen isotope fractionations between PO4 and water as a function of temperature, pH, and ionic strength, and to synthesize new silver phosphate standards for O isotope analysis following previously published and well -established experimental protocols.Intellectual Merit: The proposed research will primarily address deficiencies in calibrations of the phosphate oxygen isotope system, and a growing community-wide need for phosphate oxygen isotopic standards and standardization/comparison of recently developed analytical methods. These studies are crucial to many ongoing and future applications of oxygen isotope methods in low-temperature geochemistry as well as to studies of the geobiology of P. Research applications that will benefit from results of the proposed research include research on PO4 d18OP biosignatures and the biogeochemical cycling of P in environments and samples ranging from the marine water column, soils, sediments, hydrothermal systems and contaminated aquifers to the sub-seafloor deep biosphere; as well as general research on the metabolism of PO4 by bacteria and especially archaea whose P metabolism has not been studied in detail.Broader impacts: The silver phosphate standards for O isotope analysis of PO4 that will synthesize as part of the proposed research will be made available to the wider scientific community through the Yale Center for Stable Isotope Analysis. Also the comparison of methods of analysis of dissolved inorganic PO4 in natural waters will benefit current and future researchers employing d18OP in studies of P cycling. The proposed research will train 2 female postdoctoral associates: Dr. Lisa Stout and Dr. Saejung Chang as well as undergraduate summer interns and pre-college students involved in K-12 educational programs sponsored by the Yale Peabody Museum to which Co-PI Ruth Blake is a regular contributor. Results from the proposed studies will be incorporated into graduate and undergraduate courses in Geomicrobiology taught by PI Blake and postdoctoral associate Lisa Stout at Yale University; as well as into public presentations given at both national and international meetings. This research will also be used in K-12 teacher training internships sponsored through the EVOLUTIONS program at the Yale Peabody Museum.