Benthic Mineralization of Organic Matter on the Continental Rise and the Dissolution of CaCO 3 at the Deep Sea Floor

该项目是对海底有机质循环和成岩作用研究的继续。需要了解沉积物中生物成因元素的沉积通量、循环速率和埋藏率，以评估海洋过程对全球气候的影响，并适当解释沉积记录。该项目的最新结果提出了关于海底沉积物中碳酸钙的溶解问题，这是由于二氧化碳在孔隙水中代谢释放的结果。海底通量舱中碱度变化的模型预测了沉积物中的碱度通量，但试验室数据显示，在海底部署过程中，碱度通量很少。本研究的目标是：1.确定代谢释放的CO2对深海沉积物中CaCO_3溶解的影响；2.确定在DEA底板上准确表示CaCO_3溶解的动力学表达式。该项目的第一部分包括前往北卡罗来纳州外的大陆坡测试新的高压沉积物采样器的短途邮轮，以及P.I.对海底洞室进行的一些改造。该项目正在与Sayles和Martin(使用钢丝绳原位整体岩心挤压机)以及Reimers(使用二氧化碳微电极)在同一主题上的工作进行协调。短途测试巡航提供了测试所有设备的机会，此外，还可能提供碳酸盐溶解数据，该地区的有机碳流向海底的流量预计很高，但底层水中含有碳酸钙。这项工作的主要部分将集中在Ceara Rise-Guiana盆地地区，在该地区，含有不饱和CaCO3的南极底水的存在应会造成相当大的溶解。通过现场海底通量室(本项目)测量的碳酸盐系统参数的海底通量将与其他技术的结果进行比较。

This project is a continuation of a study of the cycling and diagenesis of organic matter at the sea floor. Knowledge of the deposition flux, cycling rate and burial rate of biogenic elements in sediments is required to assess the influence of ocean processes on global climate and to properly interpret the sedimentary record. Recent results from this project have raised questions about the dissolution of CaCO3 from sea floor sediments as a result of CO2 metabolically released in the pore water. Models of the alkalinity change in benthic flux chambers predict an alkalinity flux from the sediments, but the chamber data show little if any alkalinity flux during sea floor deployments. The goals of the present research are 1. To determine the influence of metabolically released CO2 on the dissolution of CaCO3 in deep sea sediments; 2. To determine the kinetic expression that accurately represents CaCO3 dissolution on the dea floor. The first part of the project consists of a short cruise to the continental slope off North Carolina to test a new High Pressure Sediment Sampler and some alterations to the benthic chambers by the P.I. The project is being coordinated with work on the same topic by Sayles and Martin (using a wire-line in situ whole core squeezer) and by Reimers (using PCO2 microelectrodes. The short test cruise provides an opportunity to test all the equipment and in addition may provide date on carbonate dissolution in an area where flux of organic carbon to the sea floor is predicted to be high, but bottom waters are saturated with CaCO3. The major portion of the work will be focussed on the Ceara Rise- guiana Basin region where the presence of Antarctic Bottom Water undersaturated with CaCO3 should cause significant measurable dissolution. The sea floor fluxes of carbonate system parameters measured by the in situ benthic flux chambers (this project) will be compared to the results from the other techniques.