Elevated Fe(II) and dissolved Fe in hypoxic shelf waters off Oregon and Washington: an enhanced source of iron to coastal upwelling regimes.
Elevated Fe(II) and dissolved Fe in hypoxic shelf waters off Oregon and Washington: an enhanced source of iron to coastal upwelling regimes.
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DOI：
10.1021/es800144j
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发表时间：
2008-07
影响因子：
11.4
通讯作者：
M. Lohan;K. Bruland
中科院分区：
文献类型：
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作者：
M. Lohan;K. Bruland
人们对被称为“死亡区”的缺氧区的原因和影响越来越感兴趣，这些缺氧区越来越多地出现在美国西海岸，并对这一上升流地区的螃蟹和渔业造成了广泛的破坏。在这里，我们提出的结果表明，在低氧条件下，大陆架上方的水柱导致铁(II)浓度显著增加，这有助于提高溶解的和不稳定的颗粒铁浓度。这些升高的溶解铁(II)浓度是由两个因素造成的：(1)低氧水柱允许还原孔隙水中极高的铁(II)浓度存在于靠近沉积物水界面的地方，导致沉积物中铁(II)的通量增加；(2)低氧、低pH值和底部边界层内的低温共同作用显著减缓了Fe(11)的氧化速率。在上升流条件下，这一过程可能导致可用于上升流到地表水的铁源大大增加，潜在地增加浮游植物的生产力，这反过来可能导致出口通量增加，将系统进一步推向低氧或亚低氧条件。
There has been a growing interest in the cause and impact of hypoxic regions known as "dead zones" that have increasingly appeared along the west coast of the United States and have caused widespread destruction to the crab and fishing industry in this upwelling region. Here, we present results that demonstrate that the hypoxic conditions in the water column over the continental shelf result in a marked increase in iron(II) concentrations, which contribute to elevated dissolved and labile particulate iron concentrations. These elevated dissolved iron(II) concentrations result from two factors: (1) the hypoxic water column allows extremely elevated iron(II) concentrations in reducing porewaters to exist close to the sediment water interface, leading to an increased flux of iron(II) from the sediments; (2) the low oxygen, low pH, and low temperatures within the bottom boundary layer act in concert to markedly slow down the oxidation rate of Fe(ll). During upwelling conditions, this process can result in a greatly enhanced source of Fe available to upwell to surface waters, potentially increasing phytoplankton productivity, which can, in turn, lead to enhanced export flux, driving the system further into hypoxic or suboxic conditions.