Dry and wet deposition of nutrients from the tropical Atlantic atmosphere: Links to primary productivity and nitrogen fixation
Dry and wet deposition of nutrients from the tropical Atlantic atmosphere: Links to primary productivity and nitrogen fixation
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DOI：
10.1016/j.dsr.2007.07.001
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发表时间：
2007-10-01
影响因子：
2.4
通讯作者：
Cape, J. N.
中科院分区：
文献类型：
--
作者：
Baker, A. R.;Weston, K.;Cape, J. N.
在德国海上人命安全公约方案M55巡航期间，测定了可溶性营养物（N、P、Si、Fe、Co、Zn）向热带北大西洋的大气沉降通量。养分通量最高的东部部分沿沿着10度N，由于在西非和欧洲的源区附近，最低的西部，干和湿沉积模式。与其他最近的研究一样，在M55期间大气P和Si的输入相对于浮游植物Fe，N，P和Si的化学计量需求强烈耗尽。大气氮输入相当于0.1-4.7%的观测初级生产力在巡航。大气养分供应也进行了比较，在M55期间观察到的固氮率。虽然大气Fe供应可能已经足以支持N固定（取决于我们简单的Fe浸出实验和气溶胶Fe在海水中的溶解之间的关系），大气P供应远低于所需的速率。还测定了气溶胶和雨水中硝态氮的稳定氮同位素组成。一个简单的模型的结果表明，大气沉降和固氮引入类似数量的同位素轻氮到研究区域的表面沃茨。这意味着，氮同位素为基础的方法将高估固氮在这里的一个因素2，如果不考虑大气输入。(C)2007爱思唯尔有限公司保留所有权利。
Atmospheric deposition fluxes of soluble nutrients (N, P, Si, Fe, Co, Zn) to the tropical North Atlantic were determined during cruise M55 of the German SOLAS programme. Nutrient fluxes were highest in the east of the section along 10 degrees N, owing to the proximity of source regions in West Africa and Europe, and lowest in the west, for both dry and wet deposition modes. In common with other recent studies, atmospheric P and Si inputs during M55 were strongly depleted relative to the stoichiometry of phytoplankton Fe, N, P and Si requirements. Atmospheric N inputs were equivalent to 0.1-4.7% of observed primary productivity during the cruise. Atmospheric nutrient supply was also compared to observed nitrogen fixation rates during M55. While atmospheric Fe supply may have been sufficient to support N fixation (depending on the relationship between our simple Fe leaching experiment and aerosol Fe dissolution in seawater), atmospheric P supply was well below the required rate. The stable nitrogen isotope composition of nitrate-N in aerosol and rain was also determined. Results of a simple model indicate that atmospheric deposition and nitrogen fixation introduce similar amounts of isotopically light nitrogen into surface waters of the study region. This implies that nitrogen isotope-based methods would overestimate nitrogen fixation here by a factor of 2, if atmospheric inputs were not taken into account. (C) 2007 Elsevier Ltd. All rights reserved.