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Observations of atmospheric methane-sulfonic acid (MSA) and non-sea-salt sulfate (nss-SO42-) from December 2010 to November 2011 at Zhongshan Station are presented in this paper. MSA and nss-SO42- average concentrations were 24.2 ± 37.9 ng·m-3 (0.5–158.3 ng·m-3 ) and 53.0 ± 82.6 ng·m-3 (not detected [n.d.]) – 395.4 ng·m-3 ), respectively. Strong seasonal variations of MSA and nss-SO42-, with maxima in austral summer and minima in winter, were examined. The high concentrations of sulfur compounds in December may be attributed the dimethyl sulfide (DMS) emissions from the marginal ice zone, when open water near the sampling site was important in impacting the sulfur species of January and February at Zhongshan Station. In austral winter, there was almost no phytoplanktonic activity in offshore waters, and atmospheric sulfur compounds likely had long-range transport sources.
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High volume aerosol samplersat Great Wall Station in Antarctica were used to collect 73 aerosol samples between January 2012 and November 2013. The main ions in these aerosol samples, Cl−., NO3−,SO 2−, Na+, K+, Ca2+, Mg2+, NH4+,as well as methane sulfonic acid, were analyzed using ion chromatography. Trace metals in these samples, including Pb, Cu, Cd, V, Zn, Fe, and Al, were determined by inductively-coupled plasma mass spectrometry. Results showed that sea salt was the main component in aerosols at Great Wall Station. Most ions exhibited significant seasonal variations, with higher concentrations in summer and autumn than in winter and spring. Variations in ions and trace metals were related to several processes (or sources), including sea salt emission, secondary aerosol formation, and anthropogenic pollution from both local and distant sources. The sources of ions and trace metals were identified using enrichment factor, correlation, and factor analyses. Clearly, Na+, K+, Ca2+, and Mg2+were from marine sources, while Cu, Pb, Zn, and Cd were from anthropogenic pollution, and Al and V were mainly from crustal sources.
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Atmospheric trace metals (Cu, Zn, Cd, Pb, Fe, V, and Cr), As, Al and Na in marine aerosols were studied over the Southern Ocean during the 28th Chinese National Antarctic Research Expedition. Fe was the most abundant of the analyzed trace metals, with an average concentration of 28.824 ng·m-3. V and Zn concentrations were also high, and their average concentrations were 5.541 ng·m-3 and 2.584 ng·m-3, respectively. Although sea spray significantly influenced the marine aerosol particles measured (Na had the highest concentrations of the analyzed elements, with an average concentration of 2.65 μg·m-3), multivariate analyses (enrichment factor and principal components analysis) indicated that most of the elements were not associated with oceanic sources. Over the Southern Ocean, Fe, Cd, As, Al and Cr in the aerosols mainly originated from crustal sources, while Cu, Pb, V and Zn originated from crustal sources and anthropogenic emissions. The enrichment factors (EFcrust) for most elements (Fe, Al, As, Cr, Cd, Cu and V) were much lower in the northern latitudes, indicating that when the sampling occurred closer to land the concentrations of these elements in aerosols were strongly affected by terrestrial crustal sources.
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Iodine species collected by an onboard PM10 particle sampling system during the Second Chinese National Arctic Research Expedition (July–September 2003) were measured using inductively coupled plasma mass spectrometry and ion chromatography-inductively coupled plasma mass spectrometry. Iodine (I-) was detected in all samples over the Arctic Ocean, whereas additional iodine species including insoluble iodine, soluble organic iodine plus I- were detected over the northwestern Pacific Ocean. The results suggest that the main form of iodine is different within the Arctic Ocean than it is outside. Enrichment factor values showed moderate enrichment of iodine in the northwestern Pacific, whereas a high enrichment factor was found in polar regions, implying sources other than sea salt. A potential explanation was ascribed to the role of sea ice melt in the Arctic and rapid growth of algae in seawater, which enhances the production of iodocarbon and air-sea exchange. This was confirmed by the larger values of total iodine in 2008 than in 2003, with greater sea ice melt in the former year. In comparison with earlier reports, ratios of iodate to iodide (IO3-/I-) were much smaller than 1.0. These ratios were also different from modeling results, implying more complicated cycles of atmospheric iodine than are presently understood.
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Methanesulphonic acid (MSA) may play an important role in the climate change occurring in response to the warming of the Arctic Ocean. However, the spatial and temporal distributions of MSA in this region are poorly understood. We report on the MSA content of aerosols over oceans measured during the 3rd Chinese National Arctic Research Expedition (CHINARE2008) from July to September, 2008. Results show that the aerosol MSA content can be influenced by multiple processes in different areas. In coastal regions, airborne pollutants, especially nitric oxide, may strongly influence the oxidation of dimethyl sulfide (DMS) and increase the concentration of aerosol MSA. In remote areas of the Pacific and Arctic oceans, changes in plankton will indirectly influence the airborne MSA concentration. Moreover, we found fairly similar trends in the variation of the concentrations of total iodine (TI) and MSA in the Arctic during CHINARE2008, suggesting that iodine and MSA may come from similar sources in the Arctic. Compared with the findings from other two cruises, CHINARE1999 and CHINARE2012, we found that sea ice is an extremely important factor that influences the aerosol MSA content in the Arctic. In addition, MSA concentrations may increase in the Arctic in the future caused by sea ice melting due to global warming.
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Atmospheric aerosol samples were collected from July to September 2008 onboard a round-trip cruise over the Eastern China Sea, Japan Sea, Western North Pacific Ocean, and the Arctic Ocean (31.1°N–85.18°N, 122.48°E–146.18°W). Total phosphorus (TP) and total inorganic phosphorus (TIP) were analyzed. The organic phosphorus (OP) was calculated by subtracting TIP from TP. Average concentrations of TP in the East Asia, Western North Pacific and Arctic Ocean were 7.90±6.45, 6.87±6.66 and 7.13±6.76 ng.m-3, while TIP levels were 6.67±5.02, 6.07±6.58, and 6.23±5.96 along the three regions. TP and TIP levels varied considerably both spatially and temporally over the study extent. TIP was found to be the dominant species in most samples, accounting for 86.6% of TP on average. OP was also a significant fraction of TP due to the primary biogenic aerosol (PBA) contribution. The phosphorus in the atmospheric aerosol over the Arctic Ocean had a higher concentration than previous model simulations. Source apportionment analysis indicates that dust is an important phosphorus source which can be globally transported, and thus dust aerosol may be an important nutrient source in some remote regions.
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From July to September 2008, air samples were collected aboard the R/V XUE LONG icebreaker (Snow Dragon) as part of the 2008 Chinese National Arctic Research Expedition program. Σ20PCBs in the atmosphere ranged from 6.20 to 365 pg.m.3 with average concentration 117±107 pg.m-3. Congener profiles in all samples showed a prevalence of tri- and tetrachlorobiphenyls, dominated by PCB-18, PCB-28, PCB-44 and PCB-52. Along the cruise, the highest concentration was observed over the Sea of Japan and the lowest over the high-latitude Arctic Ocean. Air mass backward trajectories indicated that samples with relatively high levels of PCBs might have been influenced by atmospheric transport of these chemicals from primary and/or secondary sources. PCB-18 displayed a significant correlation between vapor pressure and ambient temperature along the cruise, but there was no such correlation between gas-phase concentration and latitude. This suggests that atmospheric PCB-18 was related to volatilization from the earth surface during summer 2008, during which temperatures were relatively high. PCB-52 presented a significant correlation between gas-phase concentration and latitude, but no such correlation was found between vapor pressure and ambient temperature, indicating that atmospheric PCB-52 detected during the cruise might be attributed directly to atmospheric transport from source regions. In the Arctic, levels of PCB-52 in the floating sea ice region were higher than those measured in the open sea area and pack ice region. Intense ice retreat during summer 2008 might have enhanced the volatilization of previously accumulated PCBs from sea ice, especially those with heavier molecular weight and lower vapor pressure such as PCB-52.
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The concentrations of carbon monoxide and ozone in the marine boundary layer were measured during the 6th Chinese National Arctic Research Expedition (from July to September, 2014). Carbon monoxide concentration ranged between 47.00 and 528.52 ppbv with an average of 103.59 ± 40.37 ppbv. A slight decrease with increasing latitude was observed, except for the extremely high values over the East China Sea which may be attributed to anthropogenic emissions. Ozone concentration ranged between 3.27 and 77.82 ppbv with an average of 29.46±10.48 ppbv. Ozone concentration decreased sharply with increasing latitude outside the Arctic Ocean (during both the northward and the southward course), while no significant variation was observed over the Arctic Ocean. The positive correlation between carbon monoxide and ozone in most sections suggests that the ozone in the marine boundary layer mainly originated from photochemical reactions involving carbon monoxide.
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Stratosphere ozone depletion above the Arctic region has drawn increased attention recently. Here we present stratospheric ozone column densities above Ny-Åesund in the Arctic during summer 2010 and 2011, based on a self-developed passive differential optical absorption spectroscopy (DOAS) technique. By analyzing the received scattered solar spectrum, daily variations of ozone vertical column densities (VCDs) were obtained and correlated with satellite-borne ozone monitoring results and ozone sonde data. The comparisons showed good correlation, confirming the feasibility of DOAS in high-latitude Arctic regions. The preliminary analysis also demonstrated that abnormal low-level ozone columns found in spring 2011 had negative impacts on total ozone column densities over the entire year. The loss of stratospheric ozone may be correlated with low stratospheric temperatures, where heterogeneous atmospheric reactions were active.
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