Low colloidal associations of aluminium and titanium in surface waters of the tropical Atlantic
Low colloidal associations of aluminium and titanium in surface waters of the tropical Atlantic
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热带大西洋表层水中铝和钛的低胶体缔合
DOI：
10.1016/j.gca.2012.07.032
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发表时间：
2012
影响因子：
5
通讯作者：
P. L. Croot
中科院分区：
文献类型：
--
作者：
Dammshäuser;P. L. Croot
通过超滤研究了热带北大西洋东部上层水柱中Al和Ti的溶解、可溶和胶体部分的分布。两种金属的溶解部分均以小于10 kDa的可溶相为主。Al的胶体缔合率很低(0.2-3.4%)，而钛则检测不到。这些发现与之前对钛的估计以及这两种金属在海水中作为水解态的主要赋存状态形成了一定的对比。然而，可以预期形成无机胶体的倾向很低，因为在海水中，溶解的铝和溶解的钛存在于其无机溶解度水平内。此外，这两种金属都不太可能与胶体相中的官能团发生缔合。溶解组分的垂直分布显示出表面最大值，Al的最大值为43 nm，Ti的最大值为157pm，反映了它们主要来自大气来源向开阔海洋的供应。在表层水体中，与地壳来源相比，存在过量的溶解铝而不是溶解的钛，这表明更高的溶解度，从而增加了大气矿物颗粒对溶解铝的输入。在大多数测站，铝和钛的次表层极小值被观察到，并可归因于清除过程和/或生物吸收。溶解铝浓度从表层最大值到次表层最小值下降了80-90%。据估计，溶解铝在水柱上部100米处的停留时间为1.6至4年，溶解钛为14至17年。较短的停留时间与铝和钛的低胶体缔合以及胶体在清除过程中作为中间体的作用形成了一定的对比。这表明，这两种金属的去除主要是通过将水解物直接转移到颗粒组分中发生的，或者是胶体相在上层水柱中迅速翻转。
The distribution of dissolved, soluble and colloidal fractions of Al and Ti was assessed by ultrafiltration studies in the upper water column of the eastern tropical North Atlantic. The dissolved fractions of both metals were found to be dominated by the soluble phase smaller than 10kDa. The colloidal associations were very low (0.2–3.4%) for Al and not detectable for Ti. These findings are in some contrast to previous estimations for Ti and to the predominant occurrence of both metals as hydrolyzed species in seawater. However, low tendencies to form inorganic colloids can be expected, as in seawater dissolved Al and dissolved Ti are present within their inorganic solubility levels. In addition, association with functional organic groups in the colloidal phase is unlikely for both metals. Vertical distributions of the dissolved fractions showed surface maxima with up to 43nM of Al and 157pM of Ti, reflecting their predominant supply from atmospheric sources to the open ocean. In the surface waters, excess dissolved Al over dissolved Ti was present compared to the crustal source, indicating higher solubility and thus elevated inputs of dissolved Al from atmospheric mineral particles. At most stations, subsurface minima of Al and Ti were observed and can be ascribed to scavenging processes and/or biological uptake. The dissolved Al concentrations decreased by 80–90% from the surface maximum to the subsurface minimum. Estimated residence times in the upper 100m of the water column ranged between 1.6 and 4years for dissolved Al and between 14 and 17years for dissolved Ti. The short residence times are in some contrast to the low colloidal associations of Al and Ti and the assumed role of colloids as intermediates in scavenging processes. This suggests that either the removal of both metals occurs predominantly via direct transfer of the hydrolyzed species into the particulate fraction or that the colloidal phase is rapidly turned over in the upper water column.
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影响因子：
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作者：
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DOI：
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影响因子：
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DOI：
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发表时间：
1997
期刊：
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作者：
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DOI：
--
发表时间：
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期刊：
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