资源环境科技发展态势分析平台

Aerosol samples (TSP) were collected during a cruise in the North (3 degrees 05'N-34 degrees 02'N) and South (6 degrees 59'S-25 degrees 46'S) Pacific to investigate the spatio-temporal distributions of water-soluble dicarboxylic acids and related compounds. The molecular distributions of diacids were characterized by the predominance of oxalic (C-2) acid followed by malonic (C-3) and then succinic (C-4) acid. However, we found a predominance of C-4 over C-3 in the aerosol sample that was collected in the western North Pacific Rim with a heavy influence from continental air masses. Atmospheric abundances of short chain diacids (C-2-C-4) are 2-3 times higher in the North Pacific than in the South Pacific. During the cruise, abundances of C-2 in the western North Pacific are 5 times higher than those in the rest of the samples collected. Moreover, the aerosol samples collected in the western North Pacific demonstrated that glyoxylic (omega C-2) acid and methylglyoxal (MeGly) were dominant together with C-2. We found a strong correlation between C-2 and omega C-2 (r = 0.87) and C-2 and MeGly (r = 0.97) in the western North Pacific aerosols but the correlations are significantly weak in the samples from the central North Pacific and Southern Ocean. Diacids were found to account for 1.6 to 14% of organic carbon with higher values in the western North Pacific. These results, together with 7-day backward air mass trajectories, indicate that omega C-2 and MeGly are both originated from the photochemical oxidation of continent-derived organic precursors including isoprene, which can serve as precursors for the production of C-2 during long-range atmospheric transport. (C) 2016 Elsevier B.V. All rights reserved.