Phosphorus cycling in the North and South Atlantic Ocean subtropical gyres
Phosphorus cycling in the North and South Atlantic Ocean subtropical gyres
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DOI：
10.1038/ngeo232
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发表时间：
2008-07-01
影响因子：
18.3
通讯作者：
Achterberg, Eric P.
中科院分区：
文献类型：
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作者：
Mather, Rhiannon L.;Reynolds, Sarah E.;Achterberg, Eric P.
尽管物理性质相似，北方和南大西洋副热带环流具有不同的地球化学体系。北方亚热带环流受撒哈拉沙尘的铁沉积影响（1），营养磷酸盐减少，这可能是铁增强固氮作用的结果（2）。虽然磷酸盐耗尽，但北大西洋亚热带环流真光层的碳固定率与南大西洋亚热带环流的碳固定率相当（3），后者不受磷酸盐限制。在这里，我们使用磷特异性酶碱性磷酸酶的活性，以显示潜在的提高利用溶解有机磷发生在北大西洋亚热带环流。我们发现，在北方春季，北大西洋环流高达30%的初级生产力是由溶解的有机磷支持的。我们的诊断和复合地图的溶解有机磷在亚热带大西洋的表面分布揭示了较短的停留时间在北大西洋环流比南大西洋环流。我们将两个环流中溶解有机磷循环的不对称性解释为北大西洋固氮作用增强的结果（4），这迫使系统限制磷。我们认为，溶解有机磷的利用可能有助于初级生产在其他磷有限的海洋环境以及。
Despite similar physical properties, the Northern and Southern Atlantic subtropical gyres have different biogeochemical regimes. The Northern subtropical gyre, which is subject to iron deposition from Saharan dust(1), is depleted in the nutrient phosphate, possibly as a result of iron-enhanced nitrogen fixation(2). Although phosphate depleted, rates of carbon fixation in the euphotic zone of the North Atlantic subtropical gyre are comparable to those of the South Atlantic subtropical gyre(3), which is not phosphate limited. Here we use the activity of the phosphorus-specific enzyme alkaline phosphatase to show potentially enhanced utilization of dissolved organic phosphorus occurring over much of the North Atlantic subtropical gyre. We find that during the boreal spring up to 30% of primary production in the North Atlantic gyre is supported by dissolved organic phosphorus. Our diagnostics and composite map of the surface distribution of dissolved organic phosphorus in the subtropical Atlantic Ocean reveal shorter residence times in the North Atlantic gyre than the South Atlantic gyre. We interpret the asymmetry of dissolved organic phosphorus cycling in the two gyres as a consequence of enhanced nitrogen fixation in the North Atlantic Ocean(4), which forces the system towards phosphorus limitation. We suggest that dissolved organic phosphorus utilization may contribute to primary production in other phosphorus-limited ocean settings as well.