Benthic O2 and Carbonate Fluxes: Microelectrode Studies

表层深海沉积物中有机质的降解和碳酸盐的溶解控制着底栖向海水的通量以及海洋中有机碳和碳酸钙的保存程度。这些过程是用微电极测量沉积物-水界面上的电导率、氧和pH的梯度来研究的。迄今为止对某些pH结果的模拟研究表明，方解石的就地溶解速度与压力有关，速度常数比实验室测定的值小几个数量级。最近根据微电极氧和pH数据计算的通量之间的现场比较在着陆器的通量中没有观察到。这一结果与目前对海底碳酸钙溶解机制的看法不同，正在并将通过探索可能解释这种差异的机制来检验。这项研究将集中在赤道大西洋东部塞拉隆起饱和地平线上的微电极剖面和着陆器通量。这项研究是理查德·扬克博士(OCE-9201896)的合作实验，他正在进行这一领域的海底通量实验。成岩作用机制和pH测定的完整性将通过使用过去一年建造的光纤传感器测量沉积物-水界面上的二氧化碳来进行测试。

Organic matter degradation and carbonate dissolution in surficial deep-sea sediments control benthic fluxes to sea water and the extent of organic carbon and calcium carbonate preservation in the ocean. These processes are studied using microelectrodes to measure gradients of conductivity, oxygen and pH across the sediment-water interface. A modelling study of certain pH results to date reveals that the rate the in situ of calcite dissolution is pressure-dependent and the rate constant is several orders of magnitude less than laboratory-determined values. A recent field comparison between fluxes calculated from microelectrode oxygen and pH data, was not observed in the lander fluxes. This result departs from present perceptions about the mechanisms of CaCo3 dissolution on the sea floor, is and will be tested by exploring mechanisms that might explain the discrepancy. The research will focus on a transect of microelectrode profiles and lander fluxes across the saturation horizon on the Ceara Rise in the eastern equatorial Atlantic Ocean. The study is a collaborative experiment with Dr. Richard Jahnke (OCE-9201896) who is carrying out a benthic flux experiment in this area. Diagenesis mechanisms and the integrity of pH determinations will be tested by measuring pCO2 across the sediment-water interface using a fiber-optic sensor constructed during the past year.