Processes controlling the distribution and cycling of manganese in the oxygen minimum zone of the Arabian Sea
Processes controlling the distribution and cycling of manganese in the oxygen minimum zone of the Arabian Sea
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DOI：
10.1016/s0967-0645(99)00153-8
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发表时间：
2000-01-01
影响因子：
3
通讯作者：
Luther, GW
中科院分区：
文献类型：
--
作者：
Lewis, BL;Luther, GW
在1995年春季季风期间（3 - 4月;美国JGOFS过程巡航2; TN 045），在阿拉伯海（西北印度洋）的溶解和颗粒锰的垂直和水平分布进行了调查。该地区的特点是强烈的，全流域的氧气最小区（OMZ），强烈影响锰的分布。在OMZ？分别在200-300 m和600 m深度处观察到两个不同的溶解Mn（d-Mn）最大值。后一个峰值显示浓度最大值约为6纳摩尔，主要局限于北纬19度以北的站点（站点N2-N7）。这中间深度最大值与低氧气核心的OMZ（[O-2] <类似于2 μ M），并且似乎是由高度还原的巴基斯坦边缘沉积物中溶解锰的向南水平平流-扩散通量维持的，而不是像Saager等人先前提出的那样来自阿曼边缘的输入。（1989，Geochimica ct Cosmochimica Acta，53，2259-2267）。这个信号在很大程度上是不存在的站点沿着南部样带，可能是由于氧化清除d-Mn的悬浮颗粒相。在一些南部站点（站点S4-S11）的中深度微粒Mn最大值似乎是这一特征的残余。上部d-Mn最大值（200-300 m深度）比600 m峰值分布更广，在东经62度以东的大多数站点，d-Mn浓度接近3至高达8 nm。在Naqvi（1991）划定的主要反硝化区内的站点，信号到处都与次级亚硝酸盐最大值相关。类星云层，可能是细菌，也与这个深度间隔。颗粒锰配置文件显示相应的浓度最小值和低Mn/Al和活性/耐火Mn比为同一深度的间隔，这表明还原溶解锰羟基氧化物。这些观察结果意味着，在原位微生物介导的过程可能是主要来源的d-Mn在上OMZ，而水平平流是更重要的更深的水柱。(C)2000爱思唯尔科技有限公司版权所有。
Vertical and horizontal distributions of dissolved and particulate manganese were investigated in the Arabian Sea (Northwestern Indian Ocean) during the 1995 Spring Intermonsoon period (March-April; US JGOFS Process Cruise 2; TN045). The region is characterized by an intense, basin-wide oxygen minimum zone (OMZ) that strongly influences the manganese distribution. In the OMZ? two distinct dissolved Mn (d-Mn) maxima were observed, at depths of 200-300 m and 600 m, respectively. The latter peak displayed concentration maxima of approximately 6 nanomolar and was largely confined to stations north of 19 degrees N latitude (Stations N2-N7). This mid-depth maximum was associated with the low oxygen core of the OMZ ([O-2] < similar to 2 mu M), and appears to be maintained by a southward horizontal advective-diffusive flux of dissolved manganese from highly reducing Pakistan margin sediments, rather than input from the Oman Margin as previously suggested by Saager et al. (1989, Geochimica ct Cosmochimica Acta, 53, 2259-2267). This signal was largely absent at stations along the southern transect, likely due to oxidative scavenging of d-Mn to the suspended particulate phase. Mid-depth particulate Mn maxima at some southern stations (Stations S4-S11) appear to be remnants of this feature. The upper d-Mn maximum (200-300 m depth) was more widely distributed than the 600 m peak, with d-Mn concentrations of similar to 3 to as high as 8 nm at most stations east of about 62 degrees E longitude. The signal was everywhere correlated with the secondary nitrite maximum, at stations within the main denitrification zone delineated by Naqvi (1991). Nepheloid layers, presumably bacterial, also were associated with this depth interval. Particulate Mn profiles displayed corresponding concentration minima and low Mn/Al and reactive/refractory Mn ratios for this same depth interval; suggesting reductivedissolution of Mn-oxyhydroxides. These observations imply that in situ microbially mediated processes may be the predominant source of d-Mn in the upper OMZ, while horizontal advection is more important deeper in the water column. (C) 2000 Elsevier Science Ltd. All rights reserved.