ABSTRACT: Nitrogen (N) and phosphorus (P) determine the strength of the ocean’s biological carbon (C) pump, and variation in the N:P ratio is key to phytoplankton growth. A fixed C:N:P ratio (106:16:1) in organic matter and deep-water nutrients was observed by Alfred C. Redfield. However, recent studies have challenged the concept of the Redfield Ratio, and its veracity remains to be examined in oceanic basins like the Bay of Bengal. For this purpose, we sampled the water in the Bay of Bengal for C, N, and P content in the organic and inorganic pools from the surface to 2000 m. Overall, the C:N:P ratio deviated greatly from the Redfield Ratio. The C:N:P ratio in particulate organic matter varied from 232:25:1 in the top layer (surface to the depth of the chlorophyll maximum) to 966:72:1 in the deep water (300-2000 m). In dissolved organic matter, the ratio varied from 357:30:1 in the top layer to 245:66:1 in the deep water. The N:P ratio in nutrients varied from 3 in the top layer to 12 in the deep water. The nutrient-depleted top layer (average NO₃^- + NO₂^- ~ 0.7 µmol l^-1) with a low N:P ratio coupled with reported low primary production rates in the Bay suggested that the production was N limited. Concurrent N₂ fixation rates were not sufficient to alter the observed C:N:P ratio. Eddies showed a mixed effect on the C:N:P ratio. Our C:N:P ratios in particulate organic matter are comparable to other tropical basins and supports the nutrient supply hypothesis for low latitude ecosystems.

中文翻译：

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夏季季风期间孟加拉湾无机和有机池中的非Redfieldian C：N：P比

摘要：氮（N）和磷（P）决定海洋生物碳（C）泵的强度，N：P比的变化是浮游植物生长的关键。阿尔弗雷德·C·雷德菲尔德（Alfred C.Redfield）观察到有机物和深水养分中的C：N：P比例固定（106：16：1）。但是，最近的研究对“红场比率”的概念提出了挑战，其准确性是否仍需在孟加拉湾等海洋盆地中进行研究。为此，我们对孟加拉湾从地表到2000 m的有机池和无机池中的C，N和P含量进行了采样。总体而言，C：N：P比率与Redfield比率有很大差异。颗粒有机物中的C：N：P比值从顶层（表面到叶绿素最大深度）的232：25：1变化到深水（300-2000 m）中的966：72：1。在溶解的有机物中 比例从顶层的357：30：1到深水的245：66：1不等。养分中的N：P比例从顶层的3到深水中的12不等。营养耗尽的顶层（平均NON：P比低的₃ ^-- NO ₂ ^-〜0.7 µmol l ^-1）以及海湾中报道的较低的初次生产率表明该产量受到氮的限制。同时的N ₂固定率不足以改变观察到的C：N：P比率。涡流对C：N：P比率显示出混合的影响。我们在颗粒状有机质中的C：N：P比值可与其他热带盆地相媲美，并支持低纬度生态系统的养分供应假设。