Despite nutrients supply through river discharge, atmospheric deposition and eddy-driven mixing, low primary production in the Bay of Bengal (BoB) is attributed to light limitation and non-availability of nutrients during summer monsoon. We report here the first ever measurements of release of significant fraction of primary production as dissolved organic carbon (DOC) in the BoB through isotopic tracer experiments. Our results suggested that about half of the primary production is released as DOC due to existence of oligotrophic conditions, warm waters and dominance of picophytankton biomass during the summer monsoon. The mean Percentage of Extracellular Release (PER) ranged between 30 and 60% (mean of 45 ± 8%) suggesting that primary production through particulate organic matter measurements were significantly underestimated total primary production in the BoB. Higher DOC release compared to particulate organic carbon (POC) production was noticed in the cyclonic eddy (CE) regions, where high nutrients were found, than anticyclonic eddy (ACE) region, where balanced POC production and DOC release observed associating with warm waters and nutrient deplete conditions. This study suggests that primary production, including the DOC release, is not low than hitherto hypothesized due to lack of measurements on DOC and this study explains the paradox between low production and high sinking carbon fluxes to the deep BoB and underestimation of sequestration of atmospheric carbon dioxide through biological pump in the BoB.

尽管通过河流排泄，大气沉积和涡流驱动的混合来提供养分，但孟加拉湾（BoB）的初级产量较低是由于夏季季风期间光的限制和养分的缺乏。我们在此报告通过同位素示踪剂实验首次测量BoB中主要产物释放的大部分作为溶解有机碳（DOC）的释放。我们的结果表明，由于夏季季风期间存在贫营养条件，温水和皮克坦克顿生物量的优势，约有一半的初级产品以DOC的形式释放。细胞外释放（PER）的平均百分比介于30％和60％之间（平均值为45±8％），这表明通过测量颗粒有机物而产生的一次生产被大大低估了BoB的总一次生产。在旋风涡（CE）区域发现了较高的DOC释放量，而其颗粒有机碳（POC）的养分含量要高于反气旋涡（ACE）区域，在该区域中，POC产生的平衡和DOC释放与温水和高铁相关。营养耗尽的条件。这项研究表明，包括DOC版本在内的主要产品，