O'Dowd Colin D, Facchini Maria Cristina, Cavalli Fabrizia, Ceburnis Darius, Mircea Mihaela, Decesari Stefano, Fuzzi Sandro, Yoon Young Jun, Putaud Jean-Philippe
Department of Experimental Physics and Environmental Change Institute, National University of Ireland, Galway, Ireland.
Nature. 2004 Oct 7;431(7009):676-80. doi: 10.1038/nature02959.
Marine aerosol contributes significantly to the global aerosol load and consequently has an important impact on both the Earth's albedo and climate. So far, much of the focus on marine aerosol has centred on the production of aerosol from sea-salt and non-sea-salt sulphates. Recent field experiments, however, have shown that known aerosol production processes for inorganic species cannot account for the entire aerosol mass that occurs in submicrometre sizes. Several experimental studies have pointed to the presence of significant concentrations of organic matter in marine aerosol. There is some information available about the composition of organic matter, but the contribution of organic matter to marine aerosol, as a function of aerosol size, as well as its characterization as hydrophilic or hydrophobic, has been lacking. Here we measure the physical and chemical characteristics of submicrometre marine aerosol over the North Atlantic Ocean during plankton blooms progressing from spring through to autumn. We find that during bloom periods, the organic fraction dominates and contributes 63% to the submicrometre aerosol mass (about 45% is water-insoluble and about 18% water-soluble). In winter, when biological activity is at its lowest, the organic fraction decreases to 15%. Our model simulations indicate that organic matter can enhance the cloud droplet concentration by 15% to more than 100% and is therefore an important component of the aerosol-cloud-climate feedback system involving marine biota.
海洋气溶胶对全球气溶胶负荷有显著贡献，因此对地球反照率和气候都有重要影响。到目前为止，对海洋气溶胶的研究大多集中在海盐和非海盐硫酸盐产生的气溶胶上。然而，最近的实地实验表明，已知的无机物气溶胶产生过程无法解释亚微米尺寸下出现的全部气溶胶质量。几项实验研究指出，海洋气溶胶中存在大量有机物。关于有机物的组成有一些可用信息，但有机物对海洋气溶胶的贡献，作为气溶胶尺寸的函数，以及其亲水性或疏水性的特征，一直缺乏相关研究。在这里，我们测量了北大西洋浮游生物从春季到秋季繁殖期间亚微米海洋气溶胶的物理和化学特征。我们发现，在繁殖期，有机部分占主导地位，对亚微米气溶胶质量的贡献为63%（约45%为水不溶性，约18%为水溶性）。在冬季，当生物活动处于最低水平时，有机部分降至15%。我们的模型模拟表明，有机物可使云滴浓度提高15%至100%以上，因此是涉及海洋生物群的气溶胶-云-气候反馈系统的重要组成部分。
