Fine particulate matter (PM2.5) pollution, dominated by secondary inorganic aerosols (SIA), remains a critical environmental issue in China's Yangtze River Delta. In this study, we utilized hourly high-resolution measurements of water-soluble ions and precursor gases collected in suburban Nanjing from January to March 2021. By coupling these observations with the ISORROPIA-II and WRF-Chem models, we elucidated how aerosol liquid water content (ALWC) and pH govern SIA formation in ammonia (NH3)-rich environments, and further established quantitative policy thresholds for emission mitigation. Observations revealed that SIA accounted for nearly half (49.55%) of the PM2.5 mass (mean: 34.4 μg/m3), with nitrate being the dominant species. Continuous ammonia-excess conditions provided sufficient NH3 to generate ammonium (NH4+) for complete anion neutralization, driving continuous SIA accumulation. Mechanistically, rising ALWC significantly enhanced aqueous-phase oxidation and promoted the partitioning of nitrate and ammonium into the particle phase. Meanwhile, aerosol pH strictly regulated both the gas-particle partitioning equilibrium of semi-volatile species and the sulfate production pathways, with transition metal ion (TMI)-catalyzed oxidation acting as the dominant pathway. Thermodynamic sensitivity analysis indicated that local conditions were strictly total nitrate (TNO3)-limited. Simulations from both the ISORROPIA-II and WRF-Chem models revealed that due to the strong buffering effect of the substantial gaseous NH3 pool, PM2.5 mass responds minimally to moderate NH3 reductions, requiring emission cuts of over 60% to drive significant PM2.5 mitigation. In contrast, reducing nitric acid (HNO3) alone yielded a mitigation efficiency comparable to joint HNO3 and NH3 controls. Therefore, mitigating PM2.5 pollution in such NH3-rich regions requires prioritizing nitrogen oxide (NOx) emission controls, supplemented by ammonia regulations tailored to local aerosol thermodynamics.

Despite the growing anthropogenic influence on marine atmospheric composition, aerosol characterization over marginal seas lags behind urban research due to logistical challenges. This study presents a ship-based characterization of springtime PM2.5 over the Yellow Sea and the East China Sea, integrating water-soluble ions, trace metals, iron speciation, and nitrate dual isotopes (δ15N and δ18O). Secondary inorganic ions dominated aerosol composition (85.87%), while over 60% of heavy metals showed anthropogenic enrichment. A moderate positive correlation between water-soluble iron (WS-Fe) and NO3- (R2 = 0.54) indicated that nitrate-related atmospheric processes may facilitate iron dissolution, or that NO3- and WS-Fe are co-transported within the same air masses. Bayesian isotope modeling identified vehicle emissions (31.0 ± 15.8%; 95% CI: 3.0%-62.5%) and ship emissions (18.2 ± 11.1%; 95% CI: 1.2%-41.8%) as dominant NOX sources. Nighttime pathways accounted for 52.5% of nitrate formation, nearly equal to daytime hydroxyl radical (·OH) oxidation (47.5%). This work extended compound-specific isotope analysis beyond traditional source apportionment by linking isotope-constrained NOX sources to aerosol iron solubility, thereby providing a uniquely integrated dataset for China's marginal seas. The results underscored the critical role of anthropogenic nitrogen emissions in modulating marine aerosol composition and acidity, carrying profound implications for iron bioavailability and toxic metal deposition in marginal sea ecosystems.

The Southern Ocean (SO) and Antarctica play important roles in the global climate. The new particle formation (NPF) alters the availability of cloud condensation nuclei (CCN), leading to impacts on the cloud reflectance and global radiative budget. In this review, we introduce the common instruments for measuring particle number concentration (PNC) and particle number size distribution (PNSD). Based on the observations over the Antarctic and some Antarctic research stations, we explored spatial and temporal characteristics of PNCs and PNSDs. From the SO to the interior of the Antarctic, the total PNCs show a decreasing trend, and the total PNCs present an obvious seasonal cycle, with the low concentration in winter (June–August) and the high concentration in summer (December–February). By summarizing the research progress over the SO and Antarctica, we discuss possible precursors of the NPF: sulfuric acid (H2SO4, SA), methanesulfonic acid (CH3S(O)2OH, MSA), dimethyl sulfide ((CH3)2S, DMS), iodic acid (HIO3, IA), iodous acid (HIO2), ammonia (NH3), dimethylamine ((CH3)2NH, DMA), highly oxygenated organic molecules (HOMs) and other organics with low vapor pressure. We also explore several possible nucleation mechanisms: ion-induced nucleation of H2SO4 and NH3, H2SO4-amines, H2SO4-DMA-H2O, H2SO4-MSA-DMA, IA-MSA, IA-DMA, heterogeneous IA-organics nucleation mechanisms and environmental conditions required for the NPF. NPF is one of the main sources of CCN in the remote marine boundary layer, such as the SO and Antarctica. Thus, we discuss the contribution of NPF to CCN and the indirect impacts of NPF on climate. Through this review, we could better understand the PNC and NPF over the SO and Antarctica and their impacts on the global climate.

In this study, the water-soluble inorganic ions (WSIIs) composition of fine particulate matter (PM2.5) was measured in the northern Nanjing city from 2015 to 2021. NH4+, NO3− and SO42− concentrations dominated in total WSIIs (Na+, NH4+, K+, Mg2+, Ca2+, Cl−, NO3− and SO42−), accounting for 87.8%. The nitrate with highest average concentration among all ions was 11.0 μg·m−3. Total WSIIs concentrations were higher in winter and lower in summer, with the highest levels in December (45.6 μg·m−3) and the lowest levels in August (15.1 μg·m−3). NO3−/SO42− was higher than 1, indicating the important contribution of mobile sources. The aerosols exhibited a weak acidic by the molar ratio of water-soluble anions and cations. Positive matrix factorization (PMF) analysis results showed that secondary nitrate and sulfate were the major pollution sources in December 2016 and 2020. The contribution of secondary nitrate in 2020 increased by 47.6% compared to 2016, while that of secondary sulfate decreased by 42.4%. The potential source contribution results demonstrated that for secondary aerosol concentrations, the contribution of regional transport from north of Anhui increased, while the contribution of local emissions decreased. The results from this study could contribute to the better prevention and control of regional air pollution in the future.

The composition of marine aerosol is quite complex, and its sources are diverse. Across the East China Sea (ECS) and the Yellow Sea (YS), multi-dimensional analysis of marine aerosols was conducted. The characteristics of carbonaceous aerosols and gaseous pollutants were explored through in situ ship-based observation, MERRA-2 reanalysis datasets and TROPOMI data from Sentinel-5P satellite. Black carbon (BC)’s average concentration is 1.35 ± 0.78 μg/m3, with high-value BC observed during the cruise. Through HYSPLIT trajectory analysis, sources of BC were from the northern Eurasian continent, the Shandong Peninsula, the ECS and Northwest Pacific Ocean (NWPO). The transport of marine sources like ship emissions cannot be ignored. According to the absorption Angstrom exponent (AAE), BC originates from biomass burning (BB) in the shortwave band (~370 nm) and from fossil fuel combustion in the longwave band (~660 nm). Organic carbon (OC), sulfate (SO42−) and BC report higher Angstrom exponent (AE) while dust and sea salt reveal lower AE, which can be utilized to classify the aerosols as being fine- or coarse-mode, respectively. OC has the highest AE (ECS: 1.98, YS: 2.01), indicating that anthropogenic activities could be a significant source. The process of biomass burning aerosol (BBA) mixed with sea salt could contribute to the decline in BBA’s AE. Ship emissions may affect the distribution of tropospheric nitrogen dioxide (NO2) in the ECS, especially during the COVID-19 pandemic. Tropospheric NO2 over the YS has the highest value (up to 12 × 1015 molec/cm2). Stratospheric NO2 has a ladder-like distribution from north to south, and the variation gradient was lower than that in the troposphere. Carbon monoxide (CO) accumulates in the south and east of the ECS and the east of the YS, while the variation over the eastern YS is relatively frequent. Seas near the Korean Peninsula have extremely high CO concentration (up to 1.35 × 1017 molec/cm2).

To investigate mass size distributions of water-soluble ions in aerosols in the marine boundary layer (MBL) over the Southern Ocean, size-segregated (0.056-18 μm in aerodynamic diameter) aerosols were collected on the 28th Chinese National Antarctic Research Expedition (CHINARE) cruise from November 2011 to March 2012. Major water-soluble inorganic and organic species in aerosols were analyzed by ion chromatography (IC). Results showed that high loadings of aerosol mass were observed over the western sector of the Southern Ocean, attributed to the high mass loadings of Na+ and Cl- in the particles >1.0 μm in diameter and high mass loadings of non-sea-salt (nss) SO42- and methanesulfonate (MSA) in the particles <1.0 μm in diameter. Nss-SO42- and MSA accounted for ∼40% of the total mass in aerosols with particle size <0.56 μm over the eastern sector of the Southern Ocean, while it was elevated to more than 60% over the western sector of the Southern Ocean that could be linked with high marine productivity reflected by high chlorophyll-a occurrence in surface waters in that region. MSA/nss-SO42- ratios showed an increasing trend as latitude increased in the southern hemisphere with a dramatic increase south of 60 °S and the variation of MSA may shape the spatial distribution of the ratios. High MSA concentration and MSA/nss-SO42- ratios were observed in west Antarctica, especially in the supermicron particles. A bimodal mass size distribution of total Ca2+ with a small peak in the 0.18-0.32 μm size range was observed, suggesting different sea spray aerosol (SSA) production mechanisms. Nss-SO42-, MSA was mainly enriched in the particle size range of 0.18 μm to 0.56 μm. The concentrations of formate and oxalate were low and detected only in certain size particles, mainly in the range <0.56-1.8 μm. Further studies should be conducted over the remote Southern Ocean to reveal marine ecosystem-aerosol-climate interactions.

Environmental context The ocean-produced dimethyl sulfide (DMS) molecule is thought to affect cloud formation and the solar radiation budget at the Earth’s surface, hence playing an important role in regulating climate. In this study, we calculated the DMS sea-to-air flux across the Southern Ocean, south-east Indian Ocean and north-west Pacific Ocean, and analysed the influence of DMS fluxes on sulfate aerosols. These results improved our understanding of the effects of DMS emissions on sulfate compounds in the atmosphere over the global ocean. Abstract Oceanic dimethyl sulfide (DMS) is the most abundant biogenic sulfur compound emitted into the atmosphere and could indirectly regulate the global climate by impacting end product sulfate aerosols. DMS emissions and their influence on sulfate aerosols, i.e. methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO42–), were investigated over the Atlantic Ocean and Indian Ocean sectors of the Southern Ocean (SO), the south-east Indian Ocean, and the north-west Pacific Ocean from February to April 2014 during the 30th Chinese National Antarctic Research Expedition. We found a strong large-scale DMS source in the marginal sea ice zone from 34 °W to 14 °E of the SO (south of 60 °S), in which the mean flux was 49.0 ± 65.6 μmol m−2 d−1 (0.6–308.3 μmol m−2 d−1, n = 424). We also found a second large-scale DMS source in the South Subtropical Front (~40 °S, up to 50.8 μmol m−2 d−1). An inconsistency between concentrations of atmospheric sulfate compounds and DMS emissions along the cruise track was observed. The horizontal advection of air masses was likely the main reason for this discrepancy. Finally, the biological exposure calculation results also indicated that it is very difficult to observe a straightforward relationship between oceanic biomass and atmospheric MSA.

To characterize ionic composition and trace elements in the coastal Antarctic, more than 100 bulk aerosol samples were collected at the Chinese Zhongshan Station from February 2005 to November 2008. Major water-soluble species, including Na+, NH4+, K+, Mg2+, Ca2+, Cl−, NO3−, SO42−, and methane sulfonic acid (MSA), were analyzed by ion chromatography (IC). Trace metals, including Al, V, Cr, Fe, Cu, Zn, and Pb, were measured by inductively coupled plasma mass spectrometry (ICP-MS). Results showed that sea salt was the major component in aerosols at the Zhongshan Station in coastal East Antarctica. Sea salt ions Na+, Mg2+, Ca2+, and Cl− exhibited the maximum concentration in March, and the highest average concentration in September. NH4+, NO3−, SO42−, and MSA exhibited obvious seasonal variations, with higher concentrations in austral summer than in austral winter. During the 4-year observations, the highest aerosol composition loading was showed in 2008, and the high variation and average concentrations of trace metals appeared in January. Based on high NH4+/(Cl− + NO3− + 2 × SO42−) molar ratios, atmospheric aerosol was not that acidic in the austral summer. Sulfate depletion was found by the low SO42−/Na+ ratio in samples collected in the austral winter, especially from May to October. Enrichment factor (EF) and multivariate statistical analysis were utilized to explore potential emission sources of aerosols over the Zhongshan station. Na+, Cl−, K+, Mg2+, and Ca2+ were mainly from sea salt sources, and Al, Fe, Cu, Cr, Pb, and V were mainly from crustal and anthropogenic pollution sources, while S-cycle compounds non-sea-salt sulfate (nss-SO42−) and MSA originated from marine biogenic emissions.

To characterize atmospheric dissolved iron over Newark, a large metropolitan city on US east coast, size-segregated (0.056–18 μm in aerodynamic diameter) aerosols were collected in downtown Newark, New Jersey during August to October 2012. Aerosols samples were analyzed for Fe(II) and total dissolved iron (Fe(TD)) by UV/Visible spectroscopy, and water soluble compounds were analyzed by ion chromatograph (IC). Results from this study showed that Fe(II) concentrations were 2.1 ng m−3 (range: 1.2–4.2 ng m−3), Fe(TD) concentrations were 2.4 ng m−3 (range: 1.3–4.9 ng m−3). Dissolved iron (Fe(II) and Fe(TD)) in general appeared as bi-modal size distribution, was mainly accumulated in the fine mode. The highest concentration of dissolved iron displayed in the fine mode, which was associated with high concentrations of sulfate, oxalate and nitrate, suggesting the potential for Fe–acids interactions. Dissolved iron presented positive correlations with sulfate in the coarse mode, and with nitrate in the fine mode, further suggesting the importance of acid processing in aerosol iron solubility. However, as the oxalate concentration was so low, a good correlation between dissolved iron and oxalate in both the fine and coarse mode was not found.

Oil mining activities may link to the air quality in Athabasca Oil Sands Region (AOSR) in Alberta, Canada. Polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, dibenzothiophenes (DBTs), and trace metals in aerosol samples at three near source sites (AMS11, AMS05 and AMS13) in the Fort MacKay and Fort McMurray area during January 2011 to December 2014, were collected and analyzed. Concentrations of total PAHs, total alkylated PAHs, DBTs decreased as the distance from the geographical reference point increased. Average concentrations of Benzo[a]pyrene (B(a)P) and Vanadium (V) were from 0.42 to 0.68 ng m(-3), and from 1.14 to 136 ng m(-3) respectively at AMS11, from 0.10 to 0.14 ng m(-3), and from 0.79 to 1.45 ng m(-3) respectively at AMS05, and from 0.03 to 0.06 ng m(-3), and from 0.56 to 0.80 ng m(-3) respectively at AMS13 during 2011-2014. High V, B(a)P, total PAHs, total alkylated-PAHs, DBTs and Alkylated DBTs were observed in AMS11, especially in the south and south-eastern wind direction, suggesting that V and polycyclic aromatic compounds (PACs) could come from the same pollution source. High positive correlation between V and B(a)P only appeared at the AMS11 site, especially in the prevailing wind sector. Together with the principal component analysis (PCA) results and Fluoranthene/(Fluoranthene Pyrene) ratio, all further confirmed the common petrogenic source, that was petroleum coke dust, contributing to atmospheric PAHs and metals. (C) 2017 Elsevier Ltd. All rights reserved.

Multiple year-round aerosol samplings were conducted from February 2005 to October 2008 at Zhongshan Station, a research base in East Antarctica, to study methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO42-). The concentrations of atmospheric sulfur species exhibited a seasonal cycle; the maximum and minimum concentrations occurred in austral summer and austral winter, respectively. Significant correlations between chlorophyll a (Chl a) in offshore polynyas and both MSA (r = 0.726, n = 52, and p < 0.01) and nss-SO42- (r = 0.724, n = 48, and p < 0.01) were found, indicating that the phytoplankton activity had a crucial effect on the sulfur aerosols. The sea ice dynamics in the polynyas and the variations in the polynya area may indirectly influence the sulfur aerosols in austral spring and summer. In austral winter, the sulfur compounds in the atmosphere are primarily originating in long-range transported by-products from remote regions because nearly no phytoplankton activity occurred in the offshore polynyas.

To characterize the chemical composition, size distributions, and fractional Fe solubility of atmospheric particles over Asian marginal seas, South Indian Ocean and Australian coast, selected water–soluble inorganic and organic species in aerosols and precipitation, trace metals and soluble Fe in aerosols were analyzed by multi–instruments. Results showed that sea salt and non–sea–salt sulfate (nss–SO42–) were the main components in aerosols. Over Asian marginal seas, Cl– and Na+ were the dominant ions in precipitation, accounting for ˜;72% of the total ions. Both SO42– and NO3– accounted for −26% of the total anions, controlling the acidity of the precipitation. Non–sea–salt Ca2+ (nss–Ca2+) accounted for 6.9% of the total cations, dominating the neutralizing component in rainwater. Observed methane sulfonate (MSA) concentrations and MSA/nss–SO42– increased southward. The concentrations of sea salt were affected by wind speeds, which was mainly accumulated in particle size >10 μm. Particle size distributions of nss–SO42– and NH4+ mainly peaked in the fine mode, while NO3– was mainly accumulated in the coarse mode. Oxalate presented a bimodal size distribution pattern in both fine and coarse modes. Based on the air mass back trajectories, enrichment factors and Fe/Al, V/Al ratios, aerosol samples collected over Asian marginal seas could be affected by both long–range transported dust and anthropogenic emissions. Good relationship was found between total dissolved iron and nss–SO42–, indicating that acid processing during long–range transport could play an important role in fractional iron solubility in aerosols. The inverse relationship between atmospheric total Fe and fractional Fe solubility fitted in the global–scale trend. This study implicates that dust and acidic air pollutants from continental sources can interact and affect iron solubility in aerosols in the marine atmosphere. However, due to the small size of samples in this study, more investigations need to be conducted in future.

Atmospheric aerosol samples were collected over the Southern Ocean (SO) and coastal East Antarctica (CEA) during the austral summer of 2010/11. Samples were analysed for trace elements, including Na, Mg, K, Al, Fe, Mn, Ni, Cd and Se, by inductively coupled plasma mass spectrometry (ICP-MS). The mean atmospheric concentrations over the SO were 1100 ng m−3 for Na, 190 ng m−3 for Mg, 150 ng m−3 for Al, 14 ng m−3 for Fe, 0.46 ng m−3 for Mn and 0.25 ng m−3 for Se. Over CEA, the mean concentrations were 990 ng m−3 for Na, 180 ng m−3 for Mg, 190 ng m−3 for Al, 26 ng m−3 for Fe, 0.70 ng m−3 for Mn and 0.29 ng m−3 for Se. Particle size distributions, enrichment factors (EFs) and correlation analysis indicate that Na, Mg and K mainly came from the marine source, while Al, Fe and Mn were mainly from the crustal source, which also contributed to Mg and K over CEA. High EFs were associated with Ni, Cd and Se, suggesting likely contributions from mixed sources from the Antarctic continent, long-range transport, marine biogenic emissions and anthropogenic emissions. Sea-salt elements (Na, Mg, K) were mainly accumulated in the coarse mode, and crustal elements (Al, Fe, Mn) presented a bimodal size distribution pattern. Bioactive elements (Fe, Ni, Cd) were enriched in the fine mode, especially with samples collected over the SO, possibly affecting biogeochemical cycles in this oceanic region.

To characterize the concentrations and size distributions of water-soluble organic and inorganic aerosol species, including Na+, non-sea-salt sulfate (nss SO42-), 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 degrees S, 100 degrees E to 69 degrees S, 76 degrees E and between 69 degrees S, 76 degrees E and 66 degrees S, 110 degrees 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 SO42- varied from 420ngm(-3) over the SO to 480ngm(-3) over CEA. The concentrations of MSA ranged from 63 to 87ngm(-3) over the SO and from 46 to 170ngm(-3) in CEA. The average concentrations of oxalate were 3.8ngm(-3) over the SO and 2.2ngm(-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 mu m and 3.2-5.6 mu m. MSA was accumulated in particles of 0.32-0.56 mu m over CEA. High chloride depletion was associated with fine-mode particles enriched with nss SO42-, MSA, and oxalate. Higher cation-to-anion and NH4+/nss SO42- ratios in aerosols over CEA compared to that over the SO imply the higher neutralization capacity of the marine atmosphere over CEA.

We analyzed the N 2 O content of surface seawater sampled from Prydz Bay, Antarctica, on a cruise track between 30°S and 30°N during the twenty-second Chinese National Antarctic Research Expedition during austral summer, 2006. The surface water showed an average p N 2 O value of 311.9±7.6 nL·L -1 (14.1±0.4 nmol·L -1 ), which was slightly undersaturated. The air-sea N 2 O flux in the region was -0.3±0.8 μmol·m -2 ·d -1 ; however, N 2 O in the surface water was oversaturated in most stations along the cruise track. Saturation anomalies were greater than 10%, with a maximum of 54.7% being observed at the Equator, followed by 31% at 10°N in the Sulu Sea. The air-sea fluxes at these locations were 12.4 and 4 μmol·m -2 ·d -1 , respectively. Overall, the results indicated that surface water in Prydz Bay was near equilibrium with atmospheric N 2 O, and that ocean waters in lower latitudes acted as a N 2 O source. Physical processes such as stratification, ice-melt water dilution, and solar radiation dominate the factors leading to N 2 O saturation of surface water of Prydz Bay, while biological production and upwelling are primarily responsible for the N 2 O oversaturation of surface water observed in subtropical and tropical regions along the cruise track.

OF THE DISSERTATION Characterization of Atmospheric Aerosols over the Southern Ocean and Coastal East Antarctica

比较从30°N西太平洋至30°S东印度洋等热带海域与南大洋至东南极普里兹湾等南极海域的大气和表层海水N2O分压分布特征,表层海水pNO2饱和异常,分析引起异常差异性的主要影响因子。南极海域普里兹湾表层水中N2O分压（pN2O）平均为311.9±7.6 nL.L-1（14.1±0.4 nM）,与大气中N2O混合比（318.5 nL.L-1）相比显略不饱和,融冰水的输入是导致不饱和的主要原因。海气N2O通量为-0.3±0.8μmol.m-2.d-1。而热带海域多数表层海水中N2O饱和度异常值都高于10%,在赤道海域发现最高值达54.7%,次高值则位于10°N的苏禄海为31%,计算出在赤道和苏禄海的海气通量分别为～12.4μmol.m-2.d-1和～4μmol.m-2.d-1。表明高纬度的普里兹湾是大气中N2O的弱汇,而低纬度热带海域表现为大气中N2O的源。造成热带与南极海域海洋N2O饱和度异常的影响因素,可能是低纬度的热带海域由于海气间的气体交换较弱、上升流影响强,而高纬度的南极海域由于融冰分层和强偏西风的影响;而海表面风速是影响N2O的海气交换和N2O通量的重要因素。

To characterize the spatial distributions of methane‐sulfonic acid (MSA) as represented by measured aerosol methane sulfonate (MS) and its relationships with non‐sea‐salt (nss) sulfate (SO42−) in the marine atmospheric boundary layer over high‐latitude regions, bulk aerosol samples were collected during eight cruises during the Chinese National Antarctic and Arctic Research Expeditions from 1998 to 2008. The concentrations of MSA (an indicator of marine biogenic sulfur production), sulfate, sodium and chloride in samples were analyzed using ion chromatography. Increases in the aerosol MSA concentrations and MSA/nss‐SO42− ratios were observed as functions of latitudes in the Pacific Ocean, more abruptly near high southern latitudes as compared to those in high northern latitudes. The MSA concentrations increased from 0.011 μg m−3 near the equator to 0.26 μg m−3 at 63°S, 23°W and from 0.0013 μg m−3 at northern midlatitudes to 0.19 μg m−3 at 58°N, 175°E. However, MSA decreased in the latitudes north of 58°N in the Pacific, where air temperature was lower. MSA/nss‐SO42− ratios increased from 0.024 near the equator to 0.93 at 62°S, 4°E and from 0.0031 around northern midlatitudes to 0.39 at 68°N, 169°W. The MSA concentrations were more correlated with MSA/nss‐SO42− (R2 = 0.43, n = 60) in Southern Hemisphere than Northern Hemisphere (R2 = 0.091, n = 40). No significant correlation was found between MSA/nss‐SO42− and air temperature at high latitudes, indicating latitudinal temperature variations were not a main factor responsible for the MSA/nss‐SO42− variation in those regions. Substantial increases in the concentrations of MSA in coastal Antarctica may indicate additional sources of biogenic S besides the emissions of dimethylsulfide from the sea.

The ionic compositions of aerosol samples collected during the 26th Chinese National Antarctic Re-search Expedition were analyzed and the sources of ions were distinguished. Cl - Na + , SO 4 2- , NO 3 - , and Mg 2+ were the most abundant ionic components in the marine aerosols. Cl - and Na + contributed over 70% in thetotal ionic composition, indicating the sea salt is still the primary composition in marine aerosols, followed bythe sulfate as the secondary ionic component existed as NH 4 NO 3 , NH 4 HSO 4 , (NH 4 ) 2 SO 4 . The maximal seasalt concentrations were found at around 40°S and could be attributed to greater winds. The concentrations ofmethane sulfonic acid (MSA) appeared increasing trend from the low to high latitudes, possibly caused by lowertemperature in air and higher marine biological processes in the marginal waters in Antarctica. The correlationand factor analyzes were used to investigate possible sources of these ions. Cl - Br - Na + , K + , Mg 2+ and Ca 2+ had predominantly marine sources; while F - NO 3 - and NH 4 + had mostly anthropogenic sources; MSA had marinebiogenic sources. The concentrations of SO 4 2- were inflenced by both marine and anthropogenic sources.