Saharan dust inputs to the western Mediterranean Sea: Depositional patterns, geochemistry and sedimentological implications
Saharan dust inputs to the western Mediterranean Sea: Depositional patterns, geochemistry and sedimentological implications
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DOI：
10.1016/s0967-0645(96)00096-3
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发表时间：
1997-01-01
影响因子：
3
通讯作者：
Chester, R
中科院分区：
文献类型：
--
作者：
Guerzoni, S;Molinaroli, E;Chester, R
在撒丁岛的一个站收集的气溶胶和雨水的参数的数据。研究结果进行了解释，特别提到撒哈拉沙尘暴，并与其他数据相比，这些沙尘暴从地中海周围的各种网站。在撒丁岛网站的撒哈拉爆发的粒度分布呈现双峰结构，两种模式之间的2和4 μ m和15和30 μ m。巨大粒子的存在强烈影响撒哈拉气溶胶的沉积速度。撒哈拉沙尘的来源标志是坡缕石、高岭石、方解石、白云石和圆形石英颗粒。撒哈拉沙尘的输入对地中海气溶胶的化学性质有重要影响。其中包括：（i）增加的大气浓度和海表通量的地壳控制的微量金属（如铝，铁）;（ii）在EFcrust值的非地壳控制的微量金属（如铜，锌和铅）的气溶胶中的减少，和（iii）在固体的铜，锌，铅的形态变化，这降低了它们在海水中的溶解度。撒哈拉沙尘也影响雨水的组成，通过提高pH值，钙的溶解，并通过减少微量金属，如铜，锌和铅的溶解度。湿沉降控制撒哈拉沙尘的流量到地中海，但干沉降也很重要。沙尘输送以“脉冲”的形式发生，每年的沙尘通量可以由撒哈拉沙漠的几次爆发控制，例如，有时一次爆发可以占通量的40-80%。在北纬39度至42度之间的西地中海，撒哈拉的尘埃沉降通量范围为2至25 g m（-2）（平均值为10），东地中海为6至46 g m（-2）（平均值为20），欧洲大陆阿尔卑斯山为0.4至1.0 g m（-2）。目前撒哈拉的尘埃通量（约为1 mg cm（-2）年（-1））约占西地中海近期深海沉积（3-15 mg cm（-2）年（-1））的10-20%。(C)1997 Elsevier Science Ltd.
Data are presented for a number of parameters for aerosols and rainwaters collected at a station on Sardinia. The findings are interpreted with special reference to Saharan dusts, and are compared to other data on these dusts obtained from a variety of sites around the Mediterranean Sea. At the Sardinia site the particle size distribution of the Saharan outbreaks exhibits a bimodal structure, the two modes being between 2 and 4 mu m and 15 and 30 mu m. The presence of giant particles strongly affects the deposition velocities of the Saharan aerosols. Source markers for the Saharan dusts are palygorskite, kaolinite, calcite, dolomite and rounded quartz grains.The input of Saharan dust has important effects on the chemistry of the Mediterranean aerosols. These include: (i) increases in the atmospheric concentrations arid sea surface fluxes of crust-controlled trace metals (e.g. Al, Fe); (ii) decreases in the EFcrust values of non-crust-controlled trace metals (e.g. Cu, Zn and Pb) in the aerosols, and (iii) changes in the solid stare speciation of Cu, Zn, and Pb, which decrease their solubilities in seawater. The Saharan dusts also affect the composition of rainwater by raising the pH, following the dissolution of calcium,and by decreasing the solubility of trace metals such as Cu, Zn and Pb.Wet deposition controls the flux of Saharan dust to the Mediterranean Sea, but dry deposition can also be important. The dust transport occurs in the form of ''pulses'', and the annual dust flux can be controlled by a few episodes of Saharan outbreaks, e.g. sometimes a single outbreak can account for 40-80% of the flux. Saharan dust deposition fluxes range from 2 to 25 g m(-2) (average congruent to 10) in the west Mediterranean between 39 degrees and 42 degrees N, from 6 to 46 g m(-2) (average congruent to 20) in the east Mediterranean, and from 0.4 to 1.0 g m(-2) over the Alps on continental Europe. The present day Saharan dust fluxes (approximate to 1 mg cm(-2) year(-1)) account for about 10-20% of the recent deep-sea sedimentation in the western Mediterranean (3-15 mg cm(-2) year(-1)). (C) 1997 Elsevier Science Ltd.