The Distribution and Redox Speciation of Iodine in the Eastern Tropical North Pacific Ocean
The Distribution and Redox Speciation of Iodine in the Eastern Tropical North Pacific Ocean
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DOI：
10.1029/2019gb006302
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发表时间：
2020-02-01
影响因子：
5.2
通讯作者：
Moffett, James W.
中科院分区：
文献类型：
--
作者：
Moriyasu, Rintaro;Evans, Natalya;Moffett, James W.
测定了2018年东热带北太平洋（ETNP） 2个纬向样带和1个经向样带上碘酸盐（IO3-）、碘化物（I-）、亚硝酸盐（NO2-）和氧（O-2）的分布。碘是原位氧化还原转化和大陆边缘水柱输入的有用示踪剂。在含氧水中，碘主要以氧化碘酸盐的形式存在。在ETNP的缺氧区（ODZ），很大一部分被还原为碘化物，碘化物的最高浓度与次级亚硝酸盐的最大值一致。这些特征类似于阿拉伯海和东热带南太平洋（ETSP）的odz。碘化物和亚硝酸盐的最大值与特定的水质量有关，即13摄氏度的水，在ETSP中含有最高浓度的碘化物的水质量。相对于其他水团，导致13℃水体斑块的物理过程可以解释在碘化物和亚硝酸盐中经常观察到的斑块，可能反映了地下中尺度特征，如漩涡。在ETNP ODZ的大部分地区，碘浓度高于海洋平均值。这种“过量碘”归因于沉积边缘的侧向输入。过量碘的最大值集中在26.2-26.6 kg/m(3)的潜在密度范围内，该密度范围与还原性陆架沉积物相交，几乎与ETSP相同。显然，边缘输入过程在整个盆地中都很重要，并且可以影响氮和铁的循环，就像在ETSP中一样。
The distributions of iodate (IO3-), iodide (I-), nitrite (NO2-), and oxygen (O-2) were determined on two zonal transects and one meridional transect in the Eastern Tropical North Pacific (ETNP) in 2018. Iodine is a useful tracer of in situ redox transformations and inputs within the water column from continental margins. In oxygenated waters, iodine is predominantly present as oxidized iodate. In the oxygen deficient zone (ODZ) in the ETNP, a substantial fraction is reduced to iodide, with the highest iodide concentrations coincident with the secondary nitrite maxima. These features resemble ODZs in the Arabian Sea and Eastern Tropical South Pacific (ETSP). Maxima in iodide and nitrite were associated with a specific water mass, referred to as the 13 degrees C Water, the same water mass that contains the highest concentrations of iodide within the ETSP. Physical processes leading to patchiness in the 13 degrees C Water relative to other water masses could account for the patchiness frequently observed in iodide and nitrite, probably reflecting subsurface mesoscale features such as eddies. Throughout much of the ETNP ODZ, iodine concentrations were higher than the mean oceanic value. This "excess iodine" is attributed to lateral inputs from sedimentary margins. Excess iodine maxima are centered within a potential density of 26.2-26.6 kg/m(3), a density range that intersects with reducing shelf sediments and is almost identical to the ETSP. Evidently, margin input processes are significant throughout the basin and can influence the nitrogen and iron cycles as well, as in the ETSP.