Development of a Programmed-temperature Pyrolysis/Combustion Reactor System for Radiocarbon Applications

0929752 Rosenheim该提案将导致开发一种仪器，用于分离沉积物中酸不溶性有机物质（AIOM）的组分并对其进行年龄测定。成岩稳定或预老化的AIOM可能比新鲜的AIOM更能抵抗完全热解。虽然沉积物年代可以通过一系列测量来评估，但在某些情况下，AIOM年龄测定可能是唯一的选择。拟议的仪器将利用热解和燃烧产生足够数量的二氧化碳，用于放射性碳测年。广泛的应用是地质年代学和碳循环。在不同温度下的热解有差别地从复杂基质中“去除”有机物质。为了捕获热解产生的二氧化碳，已经开发了原型流通式热解系统。热谱图揭示了基于样品类型和位置的不同温度相关的二氧化碳演变。PI建议开发一种捕集系统来收集二氧化碳的“部分”。“该系统不同于任何现有的设计，因为它有一个流通配置和一个渐进的温度斜坡能力。流通系统在铂催化剂氧化炉中“终止”，以将热解部分燃烧成二氧化碳。这些二氧化碳馏分经过低温纯化，冷冻在氧化铜和粒状银上，并密封，以便在525 °C下进行冗余燃烧。这一步骤避免了任何不完全燃烧，并在AMS分析之前去除了任何干扰硫化合物。基本的科学问题要解决的成功开发的仪器，包括了解罗斯和韦德尔海冰盖的历史将估计使用热解AIOM，可以区分“新鲜”的原地和成岩碳。该设备还将用于更好地了解圭亚那泥滩中亚马逊沉积有机质的氧化情况。PI旨在确定哪些比例的OM是难降解的-即使在再氧化条件下（沉积物周转）。方法也将适用于鳗鱼河和密西西比河沉积物。该系统将用于评估富含干酪根的恒河/布拉穆帕特拉河系统沉积物的特征。初步数据显示，河流与大陆架环境的组成部分之间存在不同的年龄。将对包括与堤坝相关的区域在内的密西西比三角洲沉积物进行分析，以确定沉积事件的年代。还将评估向湿地输送的沉积物和有机物。该系统将在杜兰建造和维护。需要为反应堆部件和3个外部反应堆外壳（用于维护和减少停机时间）提供资金。要求使用红外二氧化碳分析仪进行“实时”二氧化碳量化。系统清洁需要一台真空炉。需要为阀门、LabView、数据采集硬件、继电器、真空泵和真空泵提供资金。还为放射性碳分析寻求资金。这项工作将资助一名女博士研究生助学金。仪器开发将使学生获得宝贵的仪器和电子技能。PI参与NolaSMILE（新奥尔良，洛杉矶，科学和数学探究，学习和探索），这是培训和教育当地教师的工具。该项目将包括一名来自泽维尔大学（历史上的黑人大学）的志愿者。

0929752RosenheimThis proposal will lead to the development of an instrument to separate and age date components of acid insoluble organic material (AIOM) in sediments. Diagenetically-stable or pre-aged AIOM may be more resistant to complete pyrolysis than fresh AIOM. While sediment chronologies can be assessed by a suite of measurements, in certain instances, age dating AIOM may be the only option. The proposed instrument would use both pyrolysis and combustion to generate sufficient quantities of carbon dioxide for radiocarbon dating. The broad applications are to geochronology and carbon cycling. Pyrolysis at varying temperatures differentially "removes" organic matter from a complex matrix. In order to capture pyrolysis-generated carbon dioxide, a prototype flowthrough pyrolysis system has been developed. Thermograms reveal differential temperature-related carbon dioxide evolution based on sample type and location. The PI proposes to develop a trapping system to collect carbon dioxide "fractions." The system differs from any existing design in that it has a flowthrough configuration and a gradual temperature ramp capability. The flowthrough system "ends" in a platinum catalyst oxidation furnace to combust pyrolyzed moieties into carbon dioxide. These carbon dioxide fractions are cryogenically purified, frozen onto copper oxide and granulized silver and sealed for a redundant combustion at 525 °C. This step obviates any incomplete combustion and removes any interfering sulfur compounds before AMS analysis. Basic science questions to be addressed with successful development of this instrumentation include understanding the history of the Ross and Wedell Sea ice sheets will be estimated using pyrolized AIOM which can distinguish between "fresh" autochthonous and diagenetic carbon. The device will also be employed to better understand the oxidation of Amazon-deposited OM in Guianas mud banks. The PI intends to determine which proportions of OM are refractory - even under re-oxidized conditions (sediment turnover). Methods will also be applied to Eel River and Mississippi River sediments. The system will be used to assess the characteristics of kerogen-rich Ganges/Brahmupatra river system deposits. Preliminary data show different ages amongst components of riverine vs shelf environments. Mississippi delta deposits including areas associated with levees will be analyzed in order to age date deposition events. Sediment and organic matter delivery to wetlands will also be assessed. The system will be built and maintained at Tulane. Funds are sought for reactor components and 3 external reactor housings (for maintenance and reducing downtime). An IR carbon dioxide analyzer is requested for "real-time" carbon dioxide quantization. A muffle furnace is requested for system cleaning. Funds are requested for valves, LabView, DAQ hardware, relays, vacuum solenoids and a vacuum pump. Funds are also sought for radiocarbon analysis. This effort will fund a female PhD graduate student assistantship. The instrument development will allow the student to gain valuable instrumentation and electronics skills. The PI participates in NolaSMILE (New Orleans, LA, Science and Mathematics Inquiry, Learning, and Exploring) which is a vehicle for training and educating local teachers. The project will include a volunteer undergraduate from Xavier University (historically black college).***