Greenland meltwater as a significant and potentially bioavailable source of iron to the ocean
Greenland meltwater as a significant and potentially bioavailable source of iron to the ocean
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DOI：
10.1038/ngeo1746
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发表时间：
2013-04-01
影响因子：
18.3
通讯作者：
Charette, Matthew A.
中科院分区：
文献类型：
--
作者：
Bhatia, Maya P.;Kujawinski, Elizabeth B.;Charette, Matthew A.
微量营养素铁被认为限制了全球海洋大区域的初级生产力（1）。冰盖和冰川已被证明可以将生物可利用的铁以从冰山底部释放的沉积物（2，3）和冰川衍生的灰尘（4）的形式提供给沿海和公海。从冰川径流中进行更直接的测量是有限的，但铁浓度被认为是在纳摩尔范围内（5）。在这里，我们提出的测量溶解和颗粒铁浓度的冰川融水从格陵兰冰盖的西南边缘。我们报告微摩尔浓度的溶解和颗粒铁。颗粒铁浓度平均比溶解铁的浓度高一个数量级，根据实验浸出，约50%的颗粒铁被认为是潜在的生物可利用的。如果我们的观测可扩展到整个冰盖，那么溶解的和潜在的生物可利用的颗粒铁到北大西洋的年通量约为0.3 Tg。这是可比的灰尘衍生的可溶性铁输入到北大西洋。我们认为，冰川径流作为一个重要的来源，生物可利用铁周围的沿海海洋，这是可能增加的格陵兰冰盖融化加剧气候变暖。
The micronutrient iron is thought to limit primary productivity in large regions of the global ocean(1). Ice sheets and glaciers have been shown to deliver bioavailable iron to the coastal and open ocean in the form of sediment released from the base of icebergs(2,3) and glacially derived dust(4). More direct measurements from glacial runoff are limited, but iron concentrations are thought to be in the nanomolar range(5). Here we present measurements of dissolved and particulate iron concentrations in glacial meltwater from the southwest margin of the Greenland ice sheet. We report micromolar concentrations of dissolved and particulate iron. Particulate iron concentrations were on average an order of magnitude higher than those of dissolved iron, and around 50% of this particulate iron was deemed to be potentially bioavailable, on the basis of experimental leaching. If our observations are scalable to the entire ice sheet, then the annual flux of dissolved and potentially bioavailable particulate iron to the North Atlantic Ocean would be approximately 0.3 Tg. This is comparable to dust-derived soluble iron inputs to the North Atlantic. We suggest that glacial runoff serves as a significant source of bioavailable iron to surrounding coastal oceans, which is likely to increase as melting of the Greenland ice sheet escalates under climate warming.