Characteristics of water-soluble inorganic and organic ions in aerosols over the Southern Ocean and coastal East Antarctica during austral summer

摘要

To characterize the concentrations and size distributions of water-soluble organic and inorganic aerosol species, including Na~+, non-sea-salt sulfate (nss SO_4~(2-)), methane sulfonate (MSA), oxalate, and succinate, over the Southern Ocean (SO) and coastal East Antarctica (CEA), bulk and size-segregated aerosols were collected from 40°S, 100°E to 69°S, 76°E and between 69°S, 76°E and 66°S, 110°E during a cruise from November 2010 to March 2011. Results show that sea salt was the major component of the total aerosol mass, accounting for 72% over the SO and 56% over CEA. The average concentrations of nss SO_4~(2-) varied from 420 ngm~(-3) over the SO to 480 ngm~(-3) over CEA. The concentrations of MSA ranged from 63 to 87 ngm~(-3) over the SO and from 46 to 170 ngm~(-3) in CEA. The average concentrations of oxalate were 3.8 ngm~(-3) over the SO and 2.2 ngm~(-3) over CEA. The concentrations of formate, acetate, and succinate were lower than those of oxalate. A bimodal size distribution of aerosol mass existed over CEA, peaking at 0.32–0.56 μm and 3.2–5.6 μm. MSA was accumulated in particles of 0.32–0.56 μm over CEA. High chloride depletion was associated with fine-mode particles enriched with nss SO_4~(2-), MSA, and oxalate. Higher cation-to-anion and NH_4~+ss SO_4~(2-) ratios in aerosols over CEA compared to that over the SO imply the higher neutralization capacity of themarine atmosphere over CEA.