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

海洋沉积物中有机物的微生物矿化作用对于我们理解全球O2、碳和营养物质平衡至关重要。 然而，由于微生物和化学反应的结果，在沉积物-海水界面附近通常建立O2、pH、pCO 2、NO3-、Mn 2+、Fe 2+、NH 4+和HS-的陡峭孔隙水剖面，因此很难确定有机质的矿化速率。 这些陡峭的孔隙水梯度很难量化使用传统的采样技术，采样超过厘米与毫米沉积物间隔（即。通过离心或挤压收集孔隙水）以及压力、温度和其它环境条件的限制。 微电极具有提供可靠的、非常精细的尺度和原位测量的潜力，并且对系统的干扰最小。 因此，PI建议现场测试新开发的中性载体聚合物膜pH和pCO 2微电极以及轮廓仪系统。 拟议工作的主要目标是确定组合微电极和剖面仪的分析精度和准确度，以便它们可以用于研究各种海洋环境中有机碳成岩作用和CaCO 3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.