Da Silva R, Mazumdar A, Mapder T, Peketi A, Joshi R K, Shaji A, Mahalakshmi P, Sawant B, Naik B G, Carvalho M A, Molletti S K
CSIR, National Institute of Oceanography, Donapaula, Goa, 403004, India.
ACEMS, Queensland University of Technology, Brisbane, QLD4000, Australia.
Sci Rep. 2017 Oct 31;7(1):14439. doi: 10.1038/s41598-017-14781-3.
The unique hydrographic setting of the Bay of Bengal (BoB) makes it an ideal tropical marine system to study the influence of regional and global forcings on productivity and [CO] through the late quaternary. Enormous fresh water flux into the BoB and consequent salinity stratification significantly weaken the convective mixing and wind driven processes which are commonly responsible for transport of nutrients to the euphotic zone driving primary productivity. Here we present a high resolution organic carbon-CaCO MAR and δC records for the last 300 ky from the BoB. The results show significant productivity variation at marine isotope sub-stages and millennial timescales. Colder sub-stages and stadials (Dansgard-Oeschger cycle) show a boost in productivity which may be attributed to thinning of low salinity cap, thereby facilitating efficient nutrient transport across the euphotic zone by the combination of wind driven processes (entrainment and upwelling), convective mixing and cold core eddies. The [CO] was a net result of global pCO variation and regional processes. Our long term high-resolution data indicates a possibility of marked change in productivity/biogeochemistry of BOB in the future due to global warming, thus affecting the coastal economy.
孟加拉湾独特的水文环境使其成为研究区域和全球作用力对晚第四纪生产力和[CO]影响的理想热带海洋系统。大量淡水流入孟加拉湾以及随之而来的盐度分层显著削弱了对流混合和风驱动过程，而这些过程通常负责将营养物质输送到透光层，驱动初级生产力。在此，我们展示了来自孟加拉湾过去30万年的高分辨率有机碳 - 碳酸钙 MAR 和 δC 记录。结果表明，在海洋同位素亚阶段和千年时间尺度上生产力存在显著变化。较冷的亚阶段和冰期（丹斯加德 - 厄施格循环）显示生产力有所提高，这可能归因于低盐度层变薄，从而通过风驱动过程（夹带和上升流）、对流混合和冷核涡旋的组合，促进了营养物质在透光层的有效输送。[CO]是全球pCO变化和区域过程的综合结果。我们长期的高分辨率数据表明，由于全球变暖，未来孟加拉湾的生产力/生物地球化学可能会发生显著变化，从而影响沿海经济。
