Atmospheric occurrence and deposition of polycyclic aromatic hydrocarbons in the northeast tropical and subtropical Atlantic Ocean
Atmospheric occurrence and deposition of polycyclic aromatic hydrocarbons in the northeast tropical and subtropical Atlantic Ocean
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DOI：
10.1021/es0707660
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发表时间：
2007-08-15
影响因子：
11.4
通讯作者：
Dachs, Jordi
中科院分区：
文献类型：
--
作者：
Del Vento, Sabino;Dachs, Jordi
尽管热带海洋占全球海洋的35%，但热带海洋多环芳烃（PAHs）的大气传输和沉积尚未得到研究。在这里，我们显示的结果，从测量的气体和气溶胶相多环芳烃和干沉积样品在东北热带大西洋的大气中，一个区域之间的26度和21度N，关闭撒哈拉沙漠的海岸。结果表明，近岸海域多环芳烃的浓度较高（27种气相单环芳烃之和为15-20 ng M ~（-3）），而在远海（26' W）则降低2-3倍。观察到的空间变异性与运输过程中的稀释、反应和沉积一致。大气干沉降速度范围为0.1和0.3厘米秒（-1）与更高的沉积速度为更挥发性的多环芳烃。撒哈拉沙尘暴的爆发显著增加了多环芳烃的沉积速率。多环芳烃在热带地区的发生和沉积是复杂的，是一系列过程相互作用的结果，如风速、气溶胶负荷、来自西非的重要来源、控制昼夜变化的过程以及由高初级生产力地区驱动的封存。测得的平均大气停留时间的气体和气溶胶相多环芳烃分别为3.7和3.5天。
Atmospheric transport and deposition of polycyclic aromatic hydrocarbons (PAHs) over tropical oceans has not yet been studied even though tropical oceans account for 35% of the global oceans. Here we show the results from measurements of gas- and aerosol-phase PAHs and dry deposition samples in the NE tropical Atlantic Ocean atmosphere, a region between 26 degrees and 21 degrees N, off shore of the Saharan desert. The results show that PAHs concentrations are high at the coastal ocean (15-20 ng M-3 for sum of 27 gas-phase individual PAHs) and decrease by a factor of 2-3 at open ocean (26' W). The spatial variability observed is consistent with dilution, reaction, and deposition during transport. Atmospheric dry deposition velocities ranged between 0.1 and 0.3 cm s(-1) with higher deposition velocities for the more volatile PAHs. Outbreaks of Saharan Dust significantly increase the deposition rates of PAHs. The occurrence and deposition of PAHs in tropical regions is complex and results from the interplay of a number of processes, such as wind speed, aerosol loads, important sources from West Africa, processes controlling the diurnal variability, and sequestration driven by high primary productivity regions. The measured average atmospheric residence times of gas- and aerosolphase PAHs are 3.7 and 3.5 days, respectively.