Chemistry of iron in marine aerosols
Chemistry of iron in marine aerosols
复制标题
DOI：
10.1029/92gb00756
复制
发表时间：
1992-06
影响因子：
5.2
通讯作者：
G. Zhuang;Zhen Yi;R. Duce;P. Brown
中科院分区：
文献类型：
--
作者：
G. Zhuang;Zhen Yi;R. Duce;P. Brown
抽象。远程海洋气溶胶收集在四个太平洋岛屿站（中途岛，奥陶纪，埃尼威托克，和范宁），并在四个太平洋巡航中用于确定海洋大气气溶胶中的铁的化学形式。用同样的方法研究了西安市区的气溶胶。用酸性去离子水在pH2.0 -5.6范围内淋洗中国海洋和城市气溶胶样品和黄土样品，以测定铁在大气沃茨中的溶解程度。结果表明：（1）北太平洋远海气溶胶中90%以上的大气铁以2N酸性溶液形式释放，平均约50%的大气铁以Fe（II）形式释放;在相同pH值下，海洋气溶胶中铁的溶解度比中国黄土中铁的溶解度大5-17倍，这可能是由于Fe（III）的光还原作用所致Fe（II）在其长距离运输过程中。在总铁浓度小于20 nmol/kg时，大气中约55%的铁溶解在pH为3.8的溶液中，25-30%溶解在pH为4.8的溶液中。我们认为：（1）矿物粉尘与硫酸盐/硫酸气溶胶的混合是云内凝聚过程的结果，可能是增加大气铁在云水或雨水中溶解度的一种机制;（2）Fe（III）光化学还原为Fe（II）可能是增加铁溶解度的重要机制，铁会迅速释放到雨、雾或者当气溶胶颗粒在远海上空长距离传输时与它们接触时形成云滴。整个北太平洋的大气铁输入总量估计为15 - 25 × 1012 g/年。
Abstract. Remote marine aerosols collected at four Pacific island stations (Midway, Oahu, Enewetak, and Fanning) and during four Pacific cruises were used in determining the chemical form of iron in marine atmospheric aerosols. Aerosols collected from an urban area, Xian, near the Chinese loess plateau were also studied using the same procedures. Marine and urban Chinese aerosol samples and Chinese loess samples were leached by acidic deionized water over a pH range of 2.0–5.6 to determine the extent of dissolution of iron in atmospheric waters. The results indicated that (1) more than 90% of the atmospheric iron in remote marine aerosols over the North Pacific is released in 2 N acidic solutions, and in the mean ~50% of the atmospheric iron in remote marine aerosols was in the form of Fe(II); and (2) the solubility of iron in the marine aerosols was 5–17 times greater than that of iron in Chinese loess at the same pH. This may be largely due to the photoreduction of Fe(III) to Fe(II) during its long-range transport. At a total iron concentration of less than 20 nmol/kg, ∼55% of the atmospheric iron dissolves in solutions with a pH of 3.8 and 25–30% dissolves at a pH of 4.8. We postulate that (1) the mixing of mineral dust with sulfate/sulfuric acid aerosols as a result of coalescence processes within clouds might be a mechanism to increase the solubility of atmospheric iron in cloud water or rainwater; and (2) photochemical reduction of Fe(III) to Fe(II) may be an important mechanism increasing the solubility of iron, which would be rapidly released to rainwater, fog, or cloud droplets when the aerosol particles contact them during long-range transport over the open ocean. The total atmospheric iron input was estimated to be ∼15 - 25 × 1012 g/yr for the entire North Pacific Ocean.