The Distribution of Arsenic Compounds in the Ocean: Biological Activity in the Surface Zone and Removal Processes in the Deep Zone
The Distribution of Arsenic Compounds in the Ocean: Biological Activity in the Surface Zone and Removal Processes in the Deep Zone
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海洋中砷化合物的分布：表层生物活动和深部去除过程
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
Shigeru Tanaka
中科院分区：
文献类型：
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作者：
S. J. Santosa;Hiroshige Mokudai;Miho Takahashi;Shigeru Tanaka
研究了太平洋4个采样站和南塔斯曼海1个采样站的无机砷[As(III) + As(V)]、一甲基larsonic酸（MMAA）和二甲基larsinic酸（DMAA）的垂直剖面。此外，还测定了太平洋和塔斯曼海表层水中这些化合物的浓度。垂直剖面上无机砷在地表和深/底带均呈低浓度分布。表层的耗竭浓度在1000 ~ 1700 ng dm -3之间，深层/底部的耗竭浓度在1300 ~ 2050 ng dm -3之间。通常在约2000 m的深度观察到最大浓度在1500至2450 ng dm -3之间。在太平洋西北和赤道地区取样站的整个水柱中都观测到MMAA和DMAA。在北太平洋中部环流的采样站，DMAA是在整个水柱中观察到的唯一甲基化砷化合物。相反，在南塔斯曼海采样站，整个水柱中唯一检测到的甲基化砷化合物是MMAA。它们的垂直剖面显示，地表水的浓度最大值随深度从0到200 m突然下降。地表水中MMAA的浓度接近10 ng dm -3， DMAA的浓度在27 ~ 185 ng dm -3之间变化。在大于100 m的深度，MMAA和DMAA的浓度在0.7 ~ 14 ng dm -3之间变化。表层无机砷浓度低是由于生物活性所致。这种活性导致As(V)的摄取和随后的MMAA和DMAA的还原和甲基化。DMAA是地表水生物活性产生的主要优势砷化合物。深层和底部的低无机砷浓度可能是由于溶解的无机砷吸附在富含铁和锰氧化物的下沉颗粒上所致。
The vertical profies of inorganic arsenic [As(III) + As(V)], monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) were investigated at four sampling stations in the Pacific Ocean and a sampling station in the southern Tasman Sea. In addition, the concentrations of those compounds in surface waters of the Pacific Ocean and Tasman Sea have been determined. The vertical profiles of inorganic arsenic showed the low concentrations in both the surface and deep/bottom zones. The depleted concentrations in the surface zone varied from 1000 to 1700 ng dm -3 and that in the deep/bottom zone varied from 1300 to 2050 ng dm -3 . The maximum concentrations that varied from 1500 to 2450 ng dm -3 were usually observed at a depth of about 2000 m. Both MMAA and DMAA were observed throughout the water column at sampling stations in the north-western and equatorial regions of the Pacific Ocean. At the sampling station in the central northern Pacific gyre, DMAA was the only methylated arsenic compound observed throughout the water column. On the contrary, at the sampling station in the southern Tasman Sea, the only detected methylated arsenic compound throughout the water column was MMAA. Their vertical profiles showed maximum concentrations in the surface water which abruptly dropped with depth from 0 to 200 m. The concentration in the surface water was close to 10 ng dm -3 for MMAA and varied from 27 to 185 ng dm -3 for DMAA. At depths greater than 100 m, MMAA and DMAA were at comparable concentrations which varied from 0.7 to 14 ng dm -3 . The low inorganic arsenic concentration in the surface zone was due to biological activity. This activity resulted in the uptake of As(V) and subsequent reduction and methylation to MMAA and DMAA. DMAA was the main predominant arsenic compound resulting from biological activity in surface waters. The low inorganic arsenic concentrations in the deep and bottom zones were likely to be caused by the adsorption of dissolved inorganic arsenic onto sinking particulates rich in iron and manganese oxides.