Dissolved input of manganese to the ocean: Aerosol source
Dissolved input of manganese to the ocean: Aerosol source
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锰溶解进入海洋：气溶胶来源
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
R. Arimoto
中科院分区：
文献类型：
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作者：
C. Guieu;R. Duce;R. Arimoto
在海洋区域收集了代表污染空气、多尘空气和清洁海洋空气的气溶胶颗粒样本，并用于一系列溶解研究。这些样品暴露在不同时间的海水和不同pH值的去离子(Milli-Q®)水中。在pH值为8到2之间，污染气溶胶中溶解于Milli-Q®水中的气溶胶锰的百分比从55%增加到80%。矿物气溶胶颗粒的溶解作用较小，在pH值为8~2之间，溶解的锰从25%增加到50%。与清洁海洋空气中采集的颗粒类似，我们得出结论，偏远海洋地区的气溶胶颗粒的溶解过程受背景矿物含量的控制。所有样品的海水中锰的溶解动力学都很快：暴露10min或更短的时间就达到了浓度平台。海水中受污染的气溶胶释放的溶解锰大约是矿物颗粒释放的两倍(分别为55%和30%)。显然，当雨水进入海洋时，除了明显发生在雨水中的锰溶解外，没有额外的锰溶解。气溶胶中总锰浓度与暴露在海水中的溶解浓度呈显著正相关。根据已有数据外推的关系式表明，溶解饱和值约为60nmoL L−1。考虑到不同类型颗粒的不同行为，在评估物质平衡或计算大气中锰向海洋的通量时，至少必须考虑两种情况。根据我们的溶解研究结果，在撒哈拉沙尘脉冲期间产生的大气来源的锰的溶解通量在脉冲持续时间内从0.16到0.33μ−2d−1。北欧西部人为来源的总溶解锰通量估计为0.3molmolm−2d−1。这两个实例中矿物和人为来源的溶解锰通量具有相同的数量级。为了定量估计大气输入对水柱中锰浓度的影响，必须考虑到这些不同来源的时空格局和上层水柱的动态。
Aerosol particle samples representative of polluted air, dust-laden air, and clean marine air were collected in marine regions and used in a series of dissolution studies. These samples were exposed to seawater for varying lengths of time and to deionized (Milli-Q®) water at various values of pH. The percentage of aerosol Mn dissolved in Milli-Q® water increased from 55 to 80% between pH 8 and pH 2 for pollution aerosols. Less dissolution occurred with the mineral aerosol particles, for which the dissolved Mn increased from 25 to 50% between pH 8 and pH 2. As similar behavior is found for particles collected in clean marine air, we conclude that the dissolution process for aerosol particles from a remote marine area, where crustal Mn dominates pollution Mn, is controlled by the background mineral content. The kinetics of Mn dissolution in seawater are rapid for all the samples: a concentration plateau is reached after 10 min or less of exposure. Release of dissolved Mn from polluted aerosols in seawater was approximately twice the value obtained with mineral particles (55 and 30%, respectively). Apparently, no additional Mn dissolution beyond that which has clearly taken place in rain occurs when rainwater enters the ocean. A positive relationship evidently exists between the total Mn concentration of the aerosol and the dissolved concentration after exposure in seawater. Extrapolating the relationship from the available data suggests that the dissolved saturation value is approximately 60 nmol L−1. Considering the different behavior found for the different types of particles, at least two cases must be considered when assessing mass balances or calculating atmospheric fluxes of Mn to the ocean. Based on the results of our dissolution studies, the resulting dissolved fluxes of Mn of atmospheric origin during a pulse of Saharan dust range from 0.16 to 0.33 μmol m−2d−1 over the duration of the pulse. The total dissolved Mn flux from anthropogenic sources in western North Europe is estimated to be 0.3 μmol m−2d−1. Fluxes of dissolved Mn of mineral and anthropogenic origin resulting from this calculation in the two examples selected are of the same order of magnitude. The spatial and temporal patterns of these different sources and the dynamics of the upper water column have to be taken into account to estimate quantitatively the impact of atmospheric input on Mn concentrations in the water column.