Field Evaluation of New pH and pCO2 Microelectrodes and an In Situ Profiler

清楚地了解海洋沉积物中有机物的微生物再矿化对于我们理解全球O2、碳和营养物质的质量平衡是至关重要的。然而，由于微生物和化学反应的结果，通常在沉积物-海水界面附近建立了O2、pH、PCO2、NO3-、Mn2+、Fe2+、NH4+和HS-的陡峭孔隙水剖面，因此很难确定有机质的再矿化率。这些陡峭的孔隙水梯度很难用传统的采样技术来量化，这些采样技术按厘米和毫米的沉积物间隔进行采样(即。通过离心法或挤压法收集孔隙水)以及压力、温度和其他环境条件施加的限制。微电极具有提供可靠的、非常精细的测量和现场测量的潜力，并且对系统的干扰最小。为此，PI建议对新开发的中性载体聚合物膜pH和PCO2微电极和剖面仪系统进行现场测试。拟议工作的主要目标将是确定组合微电极和剖面仪的分析精密度和准确度，以便它们可用于研究各种海洋环境中有机碳成岩作用和CaCO3的速率和机制。

ABSTRACTOCE-9911786A clear understanding of microbial remineralization of organic matter in marine sediments is critical to our understanding of global O2, carbon and nutrient mass balances. However, establishing remineralization rates of organic matter are difficult because steep porewater profiles of O2, pH, pCO2, NO3-, Mn2+, Fe2+, NH4+ and HS- are generally established near the sediment-seawater interface as a result of both microbial and chemical reactions. These steep porewater gradients are hard to quantify using conventional sampling techniques that sample over cm versus mm sediment intervals (ie. collecting porewater via centrifugation or squeezing) and limitations imposed by pressure, temperature and other environmental conditions. Microelectrodes have the potential to provide reliable, very fine scale and in-situ measurements with minimum disturbance of the system. For this reason, the PI proposes to field test newly developed neutral carrier-based polymeric membrane pH and pCO2 microelectrodes and a profiler system. The primary objective of the proposed work will be to determine the analytical precision and accuracy of the combined microelectrodes and profiler such that they can be used to study the rates and mechanisms of organic carbon diagenesis and CaCO3 in a variety of marine environments.