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

了解控制CaCO3溶解和保存的因素，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。最近的研究结果表明，沉积物孔隙水中CaCO3溶解的几个方面，特别是由CO2代谢产生驱动的溶解，受到的约束很差。这已被证明：1。在原位底栖生物通量室孵育中观察到的代谢溶解程度的区域差异，2。2 .饱和度水平上，通过原位孔隙水研究计算出的溶蚀速率没有显著变化；文石存在于被不饱和底水覆盖的表层沉积物中。之前研究过的三个区域中的两个，佛得角高原、Ontong爪哇高原和Cape Hatteras大陆隆起，将被重新研究，以进一步限制CaCO3的溶解机制。具体来说，在原位温度和压力下，将分析细尺度孔隙水样品中的Ca2+和微量金属。这些结果将增强之前已经获得的这些地区的数据集。此外，将进行底栖生物通量室原位孵育，以：1。检查室内人工制品是否影响了先前的结果，2。确定精细尺度孔隙水Ca2+梯度是否支持目前的溶解模型，并与腔室测量结果一致；检查其他酸碱反应是否影响预测的代谢溶解率。评估研究地点之间碳酸盐相的矿物学和反应性的变化；确定碳酸盐矿物表面的交换反应是否可以解释所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. ***