Enhanced Southern Ocean marine productivity due to fertilization by giant icebergs
Enhanced Southern Ocean marine productivity due to fertilization by giant icebergs
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DOI：
10.1038/ngeo2633
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发表时间：
2016-03-01
影响因子：
18.3
通讯作者：
Wilton, David J.
中科院分区：
文献类型：
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作者：
Duprat, Luis P. A. M.;Bigg, Grant R.;Wilton, David J.
由于冰山融化期间陆源营养物和微量元素的输入，威德尔海（1、2）冰山几公里范围内的初级生产力得到提高。然而，对长度超过18公里的巨型冰山对南大洋海洋初级生产的影响研究较少（1、3）。在这里，我们分析了2003年至2013年期间17座巨型冰山通过之前和之后的175张海洋颜色卫星图像。我们检测到叶绿素水平大幅提高，通常在至少4-10倍冰山长度的半径范围内，在巨型冰山通过后可以持续一个多月。这一影响范围比千米以下规模的冰山（2）或对巨型冰山的船基调查（1）大一个数量级以上。假设碳输出在影响区域内增加5-10倍，我们估计南大洋向下的碳通量中有多达五分之一来自巨型冰山施肥。我们认为，如果巨型冰山崩解在本世纪如预期的那样增加（4），这种对碳循环的负反馈可能会变得更加重要。
Primary productivity is enhanced within a few kilometres of icebergs in the Weddell Sea(1,2) owing to the input of terrigeneous nutrients and trace elements during iceberg melting. However, the influence of giant icebergs, over 18 km in length, on marine primary production in the Southern Ocean is less well studied(1,3). Here we present an analysis of 175 satellite images of open ocean colour before and after the passage of 17 giant icebergs between 2003 and 2013. We detect substantially enhanced chlorophyll levels, typically over a radius of at least 4-10 times the iceberg's length, that can persist for more than a month following passage of a giant iceberg. This area of influence is more than an order of magnitude larger than that found for sub-kilometre scale icebergs(2) or in ship-based surveys of giant icebergs(1). Assuming that carbon export increases by a factor of 5-10 over the area of influence, we estimate that up to a fifth of the Southern Ocean's downward carbon flux originates with giant iceberg fertilization. We suggest that, if giant iceberg calving increases this century as expected(4), this negative feedback on the carbon cycle may become more important.