Characterisation of water-soluble organic aerosols at a site on the southwest coast of India
Characterisation of water-soluble organic aerosols at a site on the southwest coast of India
复制标题
印度西南海岸某地点水溶性有机气溶胶的特征
DOI：
10.1007/s10874-015-9322-4
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
I. A and Prabha R. Nair
中科院分区：
文献类型：
--
作者：
Prashant Hegde;Kimitaka Kawamura;Girach;I. A and Prabha R. Nair
对在印度最南端西海岸的一个热带地区Thumba采集的气溶胶样本进行了分析，以检测同系物二元酸(C2至C12)、氧羧酸(ωC2至ωC9，丙酮酸)、α-二羰基(乙二醛和甲基乙二醛)、有机碳和元素碳的丰度。在所检测的有机物中，草酸是最丰富的物种，其次是琥珀酸和/或丙二酸。在含氧酸和α-羰基中，乙二醛和乙二醛分别占主导地位。平均而言，二元酸占气溶胶总有机碳的2.1%±50.7%。在Thumba上空的气溶胶中，草酸的形成途径有两种。在季风过后和冬季，生物和人为挥发性有机化合物的光氧化通过乙二醛、甲基乙二醛、丙酮酸和乙醛酸的连锁反应形成草酸。相反，在季风前，生物不饱和脂肪酸的氧化降解产生琥珀酸，琥珀酸可以分解为丙二酸，然后分解为草酸。观察到的酸浓度的季节变化与光化学产生和随后在该区域普遍存在的有利气象条件下的积累相一致。
Aerosol samples collected over a tropical location, Thumba, southernmost West Coast of India were analyzed for the abundance of homologous dicarboxylic acids (C2to C12), oxocarboxylic acids (ωC2to ωC9, pyruvic acid), α-dicarbonyls (glyoxal and methylglyoxal), organic and elemental carbon. Among the measured organics, oxalic acid was found to be the most abundant species followed by succinic and/or malonic acids. As oxoacid and α-carbonyl groups, glyoxylic acid and glyoxal, respectively, were observed to be dominant. On average, dicarboxylic acids accounted almost 2.1 ± 0.7 % of the aerosol total organic carbon. Among the aerosols over Thumba, two types of formation pathways were noticed for oxalic acid. During the post-monsoon and winter periods, the photo-oxidation of biogenic and anthropogenic volatile organic compounds lead to the formation of oxalic acid through a chain reaction involving glyoxal, methylglyoxal, pyruvic and glyoxylic acids. In contrast, during the pre-monsoon, the oxidative degradation of the biogenic unsaturated fatty acids give rise to succinic acid, which can be decomposed to malonic acid and then to oxalic acid. The observed seasonal variations in acid concentrations are consistent with photochemical production and the subsequent accumulation under favourable meteorological conditions prevailing over the region.