Chemical characterization of aerosols over the Atlantic Ocean and the Pacific Ocean during two cruises in 2007 and 2008

Abstract

To help understand the chemical properties of marine aerosols and the long‐distance transport of continental aerosols to remote oceanic regions, total suspended particulates (TSP) samples were collected over the Atlantic Ocean and the Pacific Ocean during two cruises in September–December 2007 (cruise I) and March–April 2008 (cruise II) aboard the M/V Oceanic II. Data were analyzed and interpreted with the aid of back trajectory, principal component, and multiple linear regression analyses. Compared with the results over the South Pacific from 2 decades ago, the non‐sea‐salt sulfate (NSS‐SO42−) concentrations over the South Pacific have increased by a factor of ∼1.5, while the NO3− concentration has remained constant. On average, NSS‐SO42− accounted for 30–52% of the total SO42− during the two cruises. Chloride deficit was observed in all samples, with NSS‐SO42− being the preferred species for acid displacement over the South Pacific and the Mediterranean Sea. Persistent clean marine air masses were only observed over the northern Atlantic and South Pacific during cruise I, while more frequent impacts of continental air (dust, biomass burning, and industrial plumes) were observed during cruise II. Combined with the NAAPS aerosol maps, these results indicate that during cruise II, (1) southern Atlantic was influenced by Southern Africa and the interhemisphere transport of biomass burning plumes in Central Africa, (2) northern Atlantic was under the combined pollution plumes of Sahara dust intrusion and biomass burning, and (3) the Mediterranean Sea was affected by the mixed pollution from biomass burning and industrial contamination, as well as Saharan dust.

Atmospheric aerosol compositions over the South China Sea: temporal variability and source apportionment

“…The annual average TSP concentrations at Yongxing Island is also lower than the annual average value over the northern Yellow Sea (123.2 µg m −3 ), another Chinese marginal sea (L. . However, the mean TSP concentrations at Yongxing Island are not lower than those at other remote islands or other seas, such as the Indian Ocean (21.1 µg m −3 ), Pacific Ocean (36.7 µg m −3 ), Mediterranean Sea (46.9 µg m −3 ), South Atlantic (39.1 µg m −3 ) and three islands of Okinawa (22.6 µg m −3 in summer and 44.5 µg m −3 in spring) (Arakaki et al, 2014;Balasubramanian et al, 2013;Zhang et al, 2010). The aforementioned annual average TSP and ionic concentrations are comparable to those reported in many remote oceans ( Fig.…”

“…Large contributions of NSS Ca 2+ were also found in the Mediterranean Sea, South Atlantic and North Atlantic 2, being at 88.4, 90.3 and 90.0 %, respectively (Zhang et al, 2010). The relatively high NSS-Ca 2+ concentrations in those oceans were potentially from the crust or dust from some deserts (Zhang et al, 2010). Comparing Yongxing Island with all locations, average Mg 2+ concentrations were higher at Yongxing Island than most reported values among all locations ( Fig.…”

“…5), such as the Indian Ocean (3.0 and 4.4 µg m −3 , respectively), Arabian Sea (1.9 and 2.2 µg m −3 , respectively), Oki (3.3 and 4.3 µg m −3 , respectively) and Rishiri islands (1.2 and 2.7 µg m −3 , respectively) in the Sea of Japan, Amsterdam Island (1.4 and 2.3 µg m −3 , respectively) in the Southern Ocean, Bermuda (3.3 and 4.8 µg m −3 , respectively) in the Atlantic Ocean and Hawaii (0.5 and 0.4 µg m −3 , respectively) in the Pacific (Kumar et al, 2008;Okuda et al, 2006;Claeys et al, 2010;Moody et al, 2014;Carrillo et al, 2002). However, Na + and Cl − concentrations were lower than samples from cruises, such as over the North Atlantic 2 (7.0 and 9.6 µg m −3 , respectively) and Pacific (5.8 and 9.0 µg m −3 , respectively) (Zhang et al, 2010). The Ca 2+ concentration was the highest among all locations and contributes 10 % of major ions (Fig.…”

“…NSS Ca 2+ accounted for 93 % of total Ca 2+ , ranging from 0.14 to 9.31 µg m −3 with an annual average of 1.99 µg m −3 . Large contributions of NSS Ca 2+ were also found in the Mediterranean Sea, South Atlantic and North Atlantic 2, being at 88.4, 90.3 and 90.0 %, respectively (Zhang et al, 2010). The relatively high NSS-Ca 2+ concentrations in those oceans were potentially from the crust or dust from some deserts (Zhang et al, 2010).…”

“…Globally, sea salt ions (Na + and Cl − ) were the most important components in marine atmospheric aerosol, with higher concentration of Cl − than Na + , except over the Mediterranean and northern seas (Fig. 5;Zhang et al, 2010;Ebert et al, 2000). In the marine atmosphere, sea salt aerosol (NaCl) can react with sulfuric acid and nitric acid to release HCl, which results in a deficit of Cl − relative to Na + (Zhang et al, 2010).…”