Mineralization of Organic Matter and Dissolution of CaCO3 atthe Deep Sea Floor

9617297 Jahnke对控制CaCO3溶解和保存的因素的了解，对于解释CaCO3沉积记录和预测沉积CaCO3、海洋化学和过程以及未来气候之间的联系至关重要。最近的结果表明，碳酸钙溶解的几个方面，特别是由沉积物孔隙水中二氧化碳的代谢产物驱动的溶解，限制得很差。这已从以下方面得到证明：1.在原位海底通量舱培养中观察到的新陈代谢溶解程度的区域差异，2.通过饱和水层的原位孔隙水研究计算的溶解速度没有显著变化，以及3.被不饱和底水覆盖的表层沉积物中文石的存在。以前研究过的三个地区中的两个，即佛得角高原、安通爪哇高原和哈特拉斯角大陆隆起，将被重新研究，以进一步限制CaCO3的溶解机制。具体地说，将在现场温度和压力下对细小规模的孔隙水样本进行钙离子和痕量金属的分析。这些结果将扩大以前已经为这些地区获得的数据集。此外，将进行现场海底通量室内培养：1.检查室内人工制品是否影响了先前的结果；2.确定细微尺度的孔隙水钙梯度是否支持目前的溶解模型并与室内测量结果一致；3.检查其他酸碱反应是否正在影响预测的代谢溶解速率；4.评估研究地点之间的矿物学和碳酸盐相反应性的变化；以及5.确定碳酸盐矿物表面的交换反应是否可以解释观察到的代谢溶解的变化。***

9617297 Jahnke Knowledge of the factors that control dissolution of CaCO3 and hence, preservation, is critical to the interpretation of the CaCO3 sedimentary record and to the prediction of the linkages between sedimentary CaCO3 , ocean chemistry and processes, and future climates. Recent results indicate that several aspects of CaCO3 dissolution, especially dissolution driven by the metabolic production of CO2 in sediment pore waters, are poorly constrained. This has been demonstrated by: 1. regional variations in the extent of metabolic dissolution observed in in situ benthic flux chamber incubations, 2. the lack of significant change in the rate of dissolution calculated from in situ pore water studies across the saturation horizon, and 3. the presence of aragonite in surface sediments that are overlain by undersaturated bottom waters. Two of the three regions, the Cape Verde Plateau, Ontong Java Plateau and Cape Hatteras continental rise, that have been studied previously will be revisited to further constrain CaCO3 dissolution mechanisms. Specifically, fine- scale pore water samples at in situ temperature and pressure will be analyzed for Ca2+ and trace metals. These results will augment the data sets already obtained for these regions previously. In addition, in situ benthic flux chamber incubations will be conducted to: 1. examine whether chamber artifacts have influenced previous results, 2. determine if fine-scale pore water Ca2+ gradients support present dissolution models and agree with chamber measurements, 3. examine whether other acid base reactions are influencing predicted metabolic dissolution rates, 4. assess variations in the mineralogy and reactivity of the carbonate phases between the study sites, and 5. determine whether exchange reactions at the carbonate mineral surface can account for the variations in metabolic dissolution observed. ***