Isotopic evidence of contaminant lead in the South Atlantic troposphere and surface waters
Isotopic evidence of contaminant lead in the South Atlantic troposphere and surface waters
复制标题
DOI：
10.1016/s0967-0645(01)00019-4
复制
发表时间：
2001-01-01
影响因子：
3
通讯作者：
Flegal, AR
中科院分区：
文献类型：
--
作者：
Alleman, LY;Church, TM;Flegal, AR
政府间海洋学委员会第三次基线污染物考察（1996年5月至6月）首次确定了赤道和南大西洋表层水和大气中的铅同位素组成。这些比率证明了沿着巡航样带（从33 degreesS到10 degreesN）铅的人为和自然来源。同位素梯度已试探性地归因于风成以及地表水平流输入从一套相当本地和远程源南半球。相对较低的Pb-206/Pb-207比值（x +/- sd）在南赤道流内17 degreesS和5 degreesS之间（1.156 +/- 0.003）。在南半球（南纬33度至23度）、巴西海流和副热带环流（1.163 +/- 0.003）以及北方半球（北纬0度至10度）（1.165 +/- 0.005）的高纬度地区，这些都被更高的放射性比率所包围。后者与北大西洋赤道洋的地表水比率（1.169 +/- 0.006）相当，受到北美西风（1.19-1.20）和欧洲东风（1.155-1.165）的综合污染影响。污染物铅的这种优势与赤道海洋表面沃茨中可测量的天然铅的存在形成对比，后者归因于撒哈拉尘埃的风成输入。在南大西洋较高纬度的表面沃茨中的铅的比例是在南极冰中也检测到的人为铅气溶胶的特征，并且也可以证实远南半球海水喷雾排放的铅的假设气溶胶再循环。大气铅同位素组成（Pb-206/Pb-207）在整体沉积物（1.171 +/- 0.006）、降水（1.171 +/- 0.006）和气溶胶（1.168 +/- 0.011）中一般比地表沃茨（1.162 +/- 0.005）更具有放射性。除了短期大气采样的代表性差之外，这种差异可能反映了大气铅排放的近期演变，而这尚未反映在海洋表面沃茨中。这也可能是由于，部分，平流铅输入从表面海洋环流的南赤道电流。(C)2001爱思唯尔科技有限公司版权所有。
The third Intergovernmental Oceanographic Commission (IOC) Baseline Contaminant cruise (May-June 1996) has established the first lead isotopic compositions in the surface water and the atmosphere of the Equatorial and South Atlantic Ocean. These ratios have evidenced both anthropogenic and natural origins of lead along the cruise transect (from 33 degreesS to 10 degreesN). The isotopic gradients tentatively have been, attributed to aeolian as well as surface-water advective inputs from a suite of rather local and remote sources to the Southern Hemisphere. Relatively low Pb-206/Pb-207 ratios (x +/- sd) were encountered within the South Equatorial Current between 17 degreesS and 5 degreesS (1.156 +/- 0.003). Those were bracketed by more radiogenic ratios at higher latitudes in the Southern Hemisphere (33 degreesS to 23 degreesS), within the Brazil Current and the Subtropical Gyre (1.163 +/- 0.003), and in the Northern Hemisphere (0 degrees to 10 degreesN) (1.165 +/- 0.005). The latter were comparable to ratios of surface water in the North Atlantic Equatorial Ocean (1.169 +/- 0.006), under a combined contaminant influence of both North American westerlies (1.19-1.20) and European easterlies (1.155-1.165). That predominance of contaminant lead contrasts with the measurable presence of natural lead in surface waters of the Equatorial Ocean, which are attributed to aeolian inputs of Saharan dust. The ratios of lead in surface waters at higher latitudes in the South Atlantic are characteristic of anthropogenic lead aerosols also detected in Antarctic ice, and could substantiate as well the hypothesized aerosol recycling of lead by sea-spray emission in the far Southern Hemisphere. The atmospheric lead isotopic compositions (Pb-206/Pb-207) in bulk depositions (1.171 +/- 0.006), precipitation (1.171 +/- 0.006) and aerosols (1.168 +/- 0.011) were, generally, more radiogenic than the surface waters (1.162 +/- 0.005). Beside a poor representation of a short term atmospheric sampling, this difference could reflect a recent evolution in atmospheric lead emissions, which have not yet been reflected in oceanic surface waters. It may also be due, in part, to advective lead inputs from surface oceanic circulation of the South Equatorial Current. (C) 2001 Elsevier Science Ltd. All rights reserved.