Marine Aerosol Samples Research Articles

Molecular compositions of marine organic aerosols over the Bohai and Yellow Seas: Influence of primary emission and secondary formation

To understand the influences of continental emissions on marine aerosols from East Asia, the total suspended particle (TSP) samples were collected from the Yellow Sea (YS) and Bohai Sea (BS) of China through a cruise campaign during the spring of 2018. >100 individual organic compounds were identified and determined in the samples, and they were classified into 6 major groups according to the functionality and sources. The mass concentrations of total quantified organic compounds in BS (307.6 ± 268.3 ng m−3) was approximately 3 times those of YS (111.0 ± 97.3 ng m−3). Organic compounds from biomass burning (23.2 ± 34.2 ng m−3), marine/microbial source (23.1 ± 6.2 ng m−3) and fossil fuel combustion (21.4 ± 11.3 ng m−3) were the most abundant in the YS samples, whereas primary biological origins (90.0 ± 107.1 ng m−3), biomass burning (52.1 ± 39.1 ng m−3) and fossil fuel combustion (41.9 ± 20.1 ng m−3) were the most important organic species in BS marine aerosols. The concentrations of total biogenic secondary organic aerosol (BSOA) tracers including six isoprene SOA (SOAI), three monoterpene SOA (SOAM), and one β-caryophyllene SOA (SOAC) were 2.4 ± 1.5 ng m−3 and 7.3 ± 4.4 ng m−3 in the YS and BS samples, respectively. A strong correlation between BSOA tracers and levoglucosan was shown in the marine aerosol samples, indicating that biomass burning emissions could also promote BSOA formations. The spatial distribution of chemical and source characteristics suggests a relatively large impacts of continental emissions to the BS aerosols. Based on the tracer-based method, the biomass burning (YS: 4.9 ± 6.8%; BS: 8.8 ± 8.0%) was the largest contributor to OC, followed by primary biogenic OC (YS: 0.59 ± 0.44%; BS: 2.9 ± 3.0%) and biogenic secondary OC (YS: 0.45 ± 0.23%; BS: 1.0 ± 0.59%). This study suggests important contributions of biomass burning emissions to organic aerosols in the YS and BS marine atmosphere, although marine source, fossil fuel combustion and secondary formation was also substantial.

Spatial and Longitudinal Distributions of Total Carbon, Nitrogen and Sulfur Together With Water‐Soluble Major Ions in Marine Aerosols Collected From the Western Pacific and Southern Ocean

AbstractTo explore the latitudinal distributions, sources and formation mechanisms of total carbon (TC), nitrogen (TN), sulfur (TS) and water‐soluble major ions (Na+, Cl−, SO42−, K+, nss‐SO42−, NH4+, NO3−, and MSA−), marine aerosol samples were collected over the Western Pacific (WP) and Southern Ocean (SO) from November 1994 to February 1995. Concentrations of TC ranged 30–390 ng m−3 (av. 190 ng m−3) over the SO, which are six times lower than those (1,200 ng m−3) over the WP, whereas concentrations of TN (av. 83 ng m−3) in the SO are three times lower than those (av. 232 ng m−3) over the WP. The highest concentrations of TC and TN were observed near New Zealand (7,000 and 720 ng m−3, respectively), suggesting a continental influence over the marine atmosphere. NO3−, tracer of anthropogenic sources, showed higher concentrations over the WP, whereas NH4+ concentrations over the SO are higher than the WP. The latter may be associated with penguin‐derived guano droppings from Antarctica. The concentration trends and statistical analysis demonstrate that the formation mechanisms of MSA− over the SO and WP is different. We found a strong correlation between MSA− and liquid water content (LWC) over the WP, suggesting the heterogenous aqueous phase production of MSA−, whereas aqueous phase reaction is less important over the SO. The strong correlation (R2 = 0.97) between nss‐Ca2+ and ss‐Ca2+ together with their similar relative abundances demonstrates an influence of CaCO3 eroded from coral reefs and shells and subsequent emission to the atmosphere by bubble bursting process.

Suppressor and calibration standard limitations in cation chromatography of ammonium and 10 alkylamines in atmospheric samples.

Ammonia (NH3) and alkylamines are ubiquitous in the atmosphere and have been suggested to play important global roles through new particle formation and aerosol growth. In this work, we optimized an ion-chromatographic (IC) method to separate and quantify the ten most abundant atmospheric alkylamines with high selectivity and separation efficiency, using 4 μm packed columns and resin-based suppressors, alongside stabilizing amine standards. Modern resin suppressors operating on a gradient elution program affected the linear response of this IC technique. Calibration statistical analyses found a loss of analytes in these cation-exchange devices. Suppressor operational longevity was optimized by using a stepped current and an external water supply, which improved precision, accuracy, and LODs compared to other suppression modes. When this new method was applied to real samples, amines were found ubiquitously in size-resolved marine aerosol samples; monopropylamine, isomonopropylamine, and monobutylamine were detected and quantified, which have not been reported before. The molar ratio of the sum of aminium to ammonium ranged from 0.02 to 0.2, showcasing the application of the developed method towards studying the diversity and importance of alkylamines in coastal marine particle composition. The new analytical method also found NH3 present in a suite of new homes with a mean mixing ratio of 25 ± 15 ppbv; a common level reached between homes across the study during the first year of occupation which can then be transported outdoors.

The Sources, Molecular Compositions, and Light Absorption Properties of Water‐Soluble Organic Carbon in Marine Aerosols From South China Sea to the Eastern Indian Ocean

AbstractWater‐soluble organic carbon (WSOC) is a substantial component of carbonaceous aerosols in South/East Asia. However, the poorly constrained sources, molecular compositions, and light absorption properties of WSOC over South/East Asian marine regions lead to large uncertainty in climate effects. Herein, we collected marine aerosol samples from South China Sea to the eastern Indian Ocean to investigate the sources, molecular compositions, and light absorption properties of WSOC. The δ13C of Marine‐influenced WSOC (−20.6 ± 1.4‰) was higher than those in Continent‐influenced (South Asia‐influenced: −24.4 ± 1.1‰ and Southeast Asia‐influenced: −22.7 ± 1.0‰, p < 0.01) regions. Additionally, combining with 5‐day back trajectories and the relationships of δ13C‐WSOC with chemical tracers (Cl−/Na+ and nonsea salt K+/K+), we found that the Marine‐influenced WSOC was mostly related to oceanic emissions, which was more enriched in saturated primary marine biological compounds with lower oxidation level. In contrast, the Continent‐influenced WSOC was significantly affected by C3 biomass burning and secondary organic aerosols formation, and it has a higher fraction of aromatic and highly oxidized compounds. Moreover, the high aromatic level of Continental‐influenced WSOC may result in high mass absorption efficiency at 365 nm (MAE365) but low absorption Ångström exponent (AAE) values. Taken together with previous WSOC light absorption properties studies, we found that the MAE365 of WSOC in urban, rural and background, and marine regions correlated well with AAE. However, the response and correlation coefficients of MAE365 to AAE were highest in urban regions, followed by rural and background and marine regions, which is likely associated with different aromatic compound contents. Therefore, in the future, more attention should be paid to the sources and atmospheric processes of condensed aromatic compounds.

Distribution Characteristics and Seasonal Variations of Arsenic in Atmospheric Aerosols over the Yellow Sea and Bohai Sea

Marine aerosol samples of total suspended particulates (TSP) were collected in winter (2017) and spring and summer (2018) over the Yellow Sea and Bohai Sea. These samples were analyzed for total arsenic (As), As(Ⅴ) and As(Ⅲ), and water soluble ions to investigate the distribution and seasonal variation of As in atmospheric aerosols, as well as the dry deposition flux. Results showed that As concentrations in winter, spring, and summer were 6.6, 5.5, and 4.4 ng·m-3, respectively. The highest As concentrations occurred in the winter. Obvious differences in the spatial distribution of As were observed in different seasons. The highest concentrations of As were observed over the Bohai Sea in winter and the northern Yellow Sea in spring, with an average of 8.8 and 11.3 ng·m-3, respectively. As concentrations exhibited a relatively uniform spatial pattern in summer over the Yellow Sea and Bohai Sea, which may have been affected by the different sources of As. As(Ⅴ) was the main species of As, while As(Ⅴ)/As(Ⅲ) ratios were 0.41 in winter and 0.21 in summer, respectively. Average As/TSP ratios in the winter, spring, and autumn were 95.4, 83.9, and 81.4 μg·g-1, respectively. Obviously higher As/TSP ratios, indicating higher intensity, occurred in winter. Air masses carry pollutants released over the Bohai Rim Region by the winter monsoon, resulting in higher As concentrations in winter. In summer, As concentrations are also higher, because air masses bring pollutants to the southeast coastal economic zone via the northeast monsoon. In spring, most air masses arriving in this region originate from Siberia and the southeast ocean with high rate, resulting in lower As concentrations. The significant correlation between K+/TSP and As/TSP (r=0.78, P<0.05) in winter indicates that As is affected by the combustion of land biomass. No significant correlation in summer reveals the difference in As sources between winter and summer. The dry deposition flux of As over the Yellow Sea and Bohai Sea was 1.15 μg·(m2·d)-1 in winter, 0.77 μg·(m2·d)-1 in spring, and 0.97 μg·(m2·d)-1 in summer, with an annual mean value of 0.95 μg·(m2·d)-1.

Molecular and spatial distributions of dicarboxylic acids, oxocarboxylic acids, and &amp;lt;i&amp;gt;α&amp;lt;/i&amp;gt;-dicarbonyls in marine aerosols from the South China Sea to the eastern Indian Ocean

Abstract. Marine aerosol samples collected from the South China Sea (SCS) to the eastern Indian Ocean (EIO) during a cruise from 10 March to 26 April 2015 were studied for diacids and related compounds. In view of air mass backward trajectories, source regions, and geographical features, the cruise area was categorized into the South China Sea (SCS), the eastern Indian Ocean off the coast of western Indonesia (EIO-WI), the EIO off the coast of Sri Lanka (EIO-SL), Malacca, and the Sri Lanka docking point (SLDP). Total concentrations of diacids, oxoacids, and α-dicarbonyls were high at the SLDP, followed by the SCS and Malacca, and they were the low in the EIO-WI. In this study, oxalic acid (C2) was the dominant diacid during the cruise, followed by malonic acid (C3) in the SCS, EIO-WI, EIO-SL, and Malacca, and succinic acid (C4) was relatively more abundant than C3 diacid at the SLDP. Except for SLDP, C3∕C4 mass ratios were always greater than 1, and no significant difference was observed during the cruise. The C2∕C4 and C2∕total diacid ratios also showed similar trends. The average mass ratios of adipic acid (C6) to azelaic acid (C9) were less than unity except for in the EIO-WI; the mass ratios of phthalic acid (Ph) to azelaic acid (C9) were less than 2 except for in the SCS. The concentrations of diacids were higher when the air masses originated from terrestrial regions than when they originated from remote oceanic regions. Based on the molecular distributions of organic acids, the mass ratios, and the linear correlations of selected compounds in each area, we found that the oxidation of biogenic volatile organic compounds (BVOCs) released from the ocean surface and subsequent in situ photochemical oxidation was the main contributor to diacids, oxocarboxylic acids, and α-dicarbonyls from the SCS to the EIO. In addition, the continental outflow, which is enriched in anthropogenic VOCs and their aged products, influenced the organic aerosol loading, particularly over the SCS. Emissions from Sri Lanka terrestrial vegetation as well as fossil fuel combustion and subsequent photochemical oxidation also played a prominent role in controlling the organic aerosol loading and the molecular distribution of diacids and related compounds at the SLDP.

Molecular Distributions and Compound-Specific Stable Carbon Isotopic Compositions of Plant Wax n-Alkanes in Marine Aerosols along a North–South Transect in the Arctic–Northwest Pacific Region

A geographical source of n-alkanes in marine aerosols was assessed along a North–South transect in the Arctic–Northwest Pacific region. Marine aerosol samples were collected during the ARA08 cruise with the R/V Araon between 28 August and 28 September 2017. We investigated molecular distributions of n-alkanes (homologous series of C16 to C34) and compound-specific stable carbon isotopes (δ13C) of n-C27, n-C29, and n-C31. Unresolved complex mixtures (UCM) showed a latitudinal trend from the Arctic Ocean to the northwest Pacific Ocean, highlighting an increasing influence of the plume of polluted air exported from East Asian countries. The anthropogenic input was further evidenced by high U/R ratios (&gt;5) and low CPI17–23 (0.6–1.4). The occurrence of high molecular weight (HMW) n-alkanes with high CPI27–31 (&gt;3) indicated the biogenic input of terrestrial higher plant leaf waxes in all studied samples. The δ13C of HMW n-alkanes was influenced by both the relative contributions from the C3/C4 plant sources and from fossil fuel combustions. The back-trajectory analyses provided evidence that changes in molecular distributions and δ13C of n-alkanes were due to the long-range atmospheric transport of anthropogenic and biogenic organic materials from North American and East Asian countries to the Arctic Ocean and the remote northwest Pacific Ocean, respectively.

Characteristics of methanesulfonic acid, non-sea-salt sulfate and organic carbon aerosols over the Amundsen Sea, Antarctica

Abstract. To investigate the characteristics of particulate methanesulfonic acid (MSA(p)), non-sea-salt sulfate (nss SO42-) and organic carbon (OC) aerosols, aerosol and seawater samples were collected over the Southern Ocean (43–70∘ S) and the Amundsen Sea (70–75∘ S) during the ANA06B cruise conducted in the austral summer of 2016 aboard the Korean icebreaker IBR/V Araon. Over the Southern Ocean, the atmospheric MSA(p) concentration was low (0.10±0.002 µg m−3), whereas its concentration increased sharply up to 0.57 µg m−3 in the Amundsen Sea where Phaeocystis antarctica (P. antarctica), a producer of dimethylsulfide (DMS), was the dominant phytoplankton species. Unlike MSA(p), the mean nss SO42- concentration in the Amundsen Sea was comparable to that in the Southern Ocean. Water-soluble organic carbon (WSOC) concentrations over the Southern Ocean and the Amundsen Sea varied from 0.048 to 0.16 and 0.070 to 0.18 µgC m−3, with averages of 0.087±0.038 and 0.097±0.038 µgC m−3, respectively. For water-insoluble organic carbon (WIOC), its mean concentrations over the Southern Ocean and the Amundsen Sea were 0.25±0.13 and 0.26±0.10 µgC m−3, varying from 0.083 to 0.49 and 0.12 to 0.38 µgC m−3, respectively. WIOC was the dominant organic carbon species in both the Southern Ocean and the Amundsen Sea, accounting for 73 %–75 % of the total aerosol organic carbon. WSOC/Na+ and WIOC/Na+ ratios in the fine-mode aerosol particles were higher, especially in the Amundsen Sea where biological productivity was much higher than the Southern Ocean. The fluorescence properties of water-soluble organic aerosols investigated using a fluorescence excitation–emission matrix coupled with parallel factor analysis (EEM–PARAFAC) revealed that protein-like components were dominant in our marine aerosol samples, representing 69 %–91 % of the total intensity. Protein-like components also showed a significant positive relationship with the relative biomass of diatoms; however, they were negatively correlated with the relative biomass of P. antarctica. These results suggest that the protein-like component is most likely produced as a result of biological processes of diatoms in the Amundsen Sea.

Shipborne measurements of Antarctic submicron organic aerosols: an NMR perspective linking multiple sources and bioregions

Abstract. The concentrations of submicron aerosol particles in maritime regions around Antarctica are influenced by the extent of sea ice. This effect is two ways: on one side, sea ice regulates the production of particles by sea spray (primary aerosols); on the other side, it hosts complex communities of organisms emitting precursors for secondary particles. Past studies documenting the chemical composition of fine aerosols in Antarctica indicate various potential primary and secondary sources active in coastal areas, in offshore marine regions, and in the sea ice itself. In particular, beside the well-known sources of organic and sulfur material originating from the oxidation of dimethylsulfide (DMS) produced by microalgae, recent findings obtained during the 2015 PEGASO cruise suggest that nitrogen-containing organic compounds are also produced by the microbiota colonizing the marginal ice zone. To complement the aerosol source apportionment performed using online mass spectrometric techniques, here we discuss the outcomes of offline spectroscopic analysis performed by nuclear magnetic resonance (NMR) spectroscopy. In this study we (i) present the composition of ambient aerosols over open-ocean waters across bioregions, and compare it to the composition of (ii) seawater samples and (iii) bubble-bursting aerosols produced in a sea-spray chamber onboard the ship. Our results show that the process of aerosolization in the tank enriches primary marine particles with lipids and sugars while depleting them of free amino acids, providing an explanation for why amino acids occurred only at trace concentrations in the marine aerosol samples analyzed. The analysis of water-soluble organic carbon (WSOC) in ambient submicron aerosol samples shows distinct NMR fingerprints for three bioregions: (1) the open Southern Ocean pelagic environments, in which aerosols are enriched with primary marine particles containing lipids and sugars; (2) sympagic areas in the Weddell Sea, where secondary organic compounds, including methanesulfonic acid and semivolatile amines abound in the aerosol composition; and (3) terrestrial coastal areas, traced by sugars such as sucrose, emitted by land vegetation. Finally, a new biogenic chemical marker, creatinine, was identified in the samples from the Weddell Sea, providing another confirmation of the importance of nitrogen-containing metabolites in Antarctic polar aerosols.

Ice Nucleation by Marine Aerosols Over the North Atlantic Ocean in Late Spring

AbstractHere we report the ice nucleating temperatures of marine aerosols sampled in the subarctic Atlantic Ocean during a phytoplankton bloom. Ice nucleation measurements were conducted on primary aerosol samples and phytoplankton isolated from seawater samples. Primary marine aerosol samples produced by a specialized aerosol generator (the Sea Sweep) catalyzed droplet freezing at temperatures between −33.4 °C and − 24.5 °C, with a mean freezing temperature of −28.5 °C, which was significantly warmer than the homogeneous freezing temperature of pure water in the atmosphere (−36 °C). Following a storm‐induced deep mixing event, ice nucleation activity was enhanced by two metrics: (1) the fraction of aerosols acting as ice nucleating particles (INPs) and (2) the nucleating temperatures, which were the warmest observed throughout the project. Seawater samples were collected from the ocean's surface and phytoplankton groups, including Synechococcus, picoeukaryotes, and nanoeukaryotes, were isolated into sodium chloride sheath fluid solution using a cell‐sorting flow cytometer. Marine aerosol containing Synechococcus, picoeukaryotes, and nanoeukaryotes serves as INP at temperatures significantly warmer than the homogeneous freezing temperature of pure water in the atmosphere. Samples containing whole organisms in 30 g L−1 NaCl had freezing temperatures between −33.8 and − 31.1 °C. Dilution of samples to representative atmospheric aerosol salt concentrations (as low as 3.75 g L−1 NaCl) raised freezing temperatures to as high as −22.1 °C. It follows that marine aerosols containing phytoplankton may have widespread influence on marine ice nucleation events by facilitating ice nucleation.

Aeolian transport and deposition of carbonaceous aerosols over the Northwest Pacific Ocean in spring

The present study provides insight into the long-range transport of carbonaceous aerosols over the Northwest Pacific Ocean (NWP) based on marine aerosol samples collected onboard a research vessel in the spring of 2015. Organic carbon (OC) and elemental carbon (EC) concentrations showed maxima in proximity to land, with high levels also observed in advective air masses. The decoupled spatial variations in OC and EC levels in relatively pristine air masses from the Pacific, in which aerosol n-alkanes of marine origin were relatively high in abundance, revealed the influence of heterogeneity in air masses and suggested the release of n-alkanes from local marine environments. This was confirmed by the enhanced particle-bound fraction of marine organic matter-sourced n-alkanes, resulting in non-significant relationships between the gas–particle partition coefficient of n-alkanes and the corresponding sub-cooled liquid vapor pressure in some marine air masses. High OC/EC ratios over the NWP indicated secondary organic aerosol formation, possibly as a result of marine emissions followed by gas-to-particle conversion and/or aerosol aging during long-range transport from East Asia. Similar molecular profiles of n-alkanes were found in air and seawater particles in regions dominated by either marine or continental influence, reflecting the strengths of continental and/or marine input and more importantly, suggesting the occurrence of air–sea exchange through wind-induced marine emissions or atmospheric deposition. Relative to the East China Sea, dry particle deposition after long-range transport acted as a more important source for terrestrial lipids in the open NWP.

Analysis of levoglucosan and its isomers in atmospheric samples by ion chromatography with electrospray lithium cationisation - Triple quadrupole tandem mass spectrometry

Biomass burning (BB) emissions are a significant source of particles to the atmosphere, especially in the Southern Hemisphere, where the occurrence of anthropogenic and natural wild fires is common. These emissions can threaten human health through increased exposure, whilst simultaneously representing a significant source of trace metals and nutrients to the ocean. One well known method to track BB emissions is through monitoring the atmospheric concentration of specific monosaccharide anhydrides (MAs), specifically levoglucosan and its isomers, mannosan and galactosan. Herein, a new method for the determination of levoglucosan and its isomers in marine and terrestrial aerosol samples is presented, which delivers both high selectivity and sensitivity, through the coupling of ion chromatography and triple quadrupole tandem mass spectrometry. Optimal chromatographic conditions, providing baseline separation for target anhydrosugars in under 8 min, were obtained using a Dionex CarboPacⓇ PA-1 column with an electrolytically generated KOH gradient. To improve the ionisation efficiency for MS detection, an organic make-up solvent was fed into the IC column effluent before the ESI source, and to further increase both sensitivity and selectivity, cationisation of levoglucosan was investigated by adding salts into the make-up solvent, namely, sodium, ammonium and lithium salts. Using positive lithium cationisation with 0.5 mM lithium chloride in methanol as the make-up solvent, delivered at a flow rate of 0.02 mL min–1, the levoglucosan response was improved by factors of 100 and 10, comparing to negative ionisation and positive sodium cationisation, respectively. Detection was carried out in SRM mode for quantitation and identification, achieving an instrumental LOD of 0.10, 0.12 and 0.5 µg L−1 for levoglucosan, mannosan and galactosan, respectively. Finally, the method was applied to the analysis of 41 marine and terrestrial aerosol samples from Australia, its surrounding coastal waters and areas within the remote Southern Ocean, covering a large range of BB marker concentrations.

Characteristics and sources of organic carbon in coastal and marine atmospheric particulates over East China

To understand the influences of emission sources, transport and environmental factors on the characteristics of organic carbonaceous aerosols in the marine area, organic carbon (OC) and water-soluble organic carbon (WSOC) were measured in atmospheric samples collected from the coastal region and over the Bohai and Yellow Seas from 2015 to 2016. Compared with the averages of 19.28 and 10.61 μg·m−3 in the coastal samples, the average concentrations of OC and WSOC decreased to 2.17 and 1.54 μg·m−3 in the marine aerosol samples, respectively. WSOC contributed 60% to OC in Qingdao, while 68.4% to OC over the ocean, suggesting that WSOC is likely influenced by the dissolved organic carbon (DOC) in surface seawater. The highest OC/EC ratios (6.56) were observed in the samples collected from the air masses originating from the north land source, indicating that OC mainly comes from anthropogenic sources. The OC concentrations in the air mass samples from marine sources were only 50% of those in the samples from terrestrial sources. A negative correlation between the WSOC and transport distance over the sea and decreased OC/EC ratios were observed, which indicated that the contribution of secondary organic carbon (SOC) to OC decreased during the transport from land to sea. OC increased by 88.5% under the influence of Asian dust, while WSOC did not exhibit substantial changes. The positive matrix factorization (PMF) model showed that anthropogenic sources were the major source of carbonaceous aerosols, contributing 70% of the OC in Qingdao. The positive correlation between OC and particulate matter (PM) suggested that the OC affected the air quality.

Impact of a Dust Event on the Size Distribution of Metal Elements in Atmospheric Aerosols at a Coastal Region and over the Ocean

Size-segregated aerosol samples were collected in the Qingdao coastal region and over the East Sea and the Pacific Northwest from March to April in 2016, and the concentration of metal elements (Al, Na, Fe, Mg, K, Cu, Pb, and Cd) were analyzed. The characteristics and the variation in the size distribution of the metal elements in the samples during dusty weather were discussed, as well as the sources and factors that influence the metals. The results indicated that the concentration of Al, Fe, K, Na, Cu, and Pb in the aerosols in the Qingdao coastal samples increased significantly by 85%-1400%, while the concentration of Cd decreased by 8%; the concentrations of Al, Fe, K, Cu, Pb, and Cd in the samples over the ocean increased by 163%-4580%, while the concentration of Na decreased by 62% during dusty weather. In addition, the size distribution of K changed from a double-peak to a coarse peak mode; that of Pb and Cd changed from a fine peak mode to a double-peak distribution. Cu still presented a double-peak distribution in which the proportion of coarse particles increased; Al, Fe, Mg, and Na showed little variation in their size distribution with a single peak in coarse mode. The dust event had different effects on the size distributions of the metal elements in the coastal and marine aerosol samples. The size distribution of the metal elements (Al, Fe, Mg, Na, and K) in the aerosols collected at the Qingdao coastal site had one peak of 2.1-3.3 μm during dusty weather; the peak moved to 3.3-4.7 μm for marine samples. In addition, the proportion of Al, Fe, Mg, Na, K, Pb, and Cd in the coarse mode decreased by 1%-35% for dust aerosol samples collected in Qingdao coastal region, whereas the proportion of these metals in coarse mode increased by 4%-33% for samples collected over the East Sea. This difference may be related to the hygroscopic growth, transport path, and height of the dust.

Mixed-mode SPE followed by GC-MS analysis to determine water soluble organic compounds in aerosol and historical mortars affected by marine atmosphere: The case of Punta Begoña Galleries (Getxo, North of Spain)

This work describes the development of an analytical procedure for the determination of short chain dicarboxylic acids (C2-C10) both in aqueous and solid matrices such as aerosols and mortars. The developed and validated methodology was based on the preconcentration of compounds by means of mixed-mode solid phase extraction and gas chromatography-mass spectrometry, regardless the analyzed samples. In the case of solid samples, a prior extraction of target compounds using ultrasonic probe-assisted solid-liquid extraction was required. In general terms, the developed procedure rendered good results in terms of accuracy (apparent recoveries in the range 90–130% and 86–98% for marine aerosol and mortar samples, respectively) and repeatability (%RSD < 25%) except for those compounds interacting more strongly with the solid matrix and being more reactive. The method was applied to detect dicarboxylic acids in marine aerosol water samples and in mortars of a 20th century historical building (Punta Begoña Galleries, Getxo) located in a coastal environment (Biscay Gulf, Basque Country, Northern Spain) with industrial activity. According to the results, harbor activities may have effect on the concentrations of dicarboxylic acids found in both matrices since the façade of the building exposed to the industrial harbor (southwest orientation) appears to be more contaminated than the one oriented to the northwest.

Impact of northern and southern air mass transport on the temporal distribution of atmospheric (210)Po and (210)Pb in the east coast of Johor, Malaysia.

Concentration activities of (210)Pb and (210)Po in the PM10 were determined to discuss their distribution and chemical behavior in relation to meteorological parameters especially in air mass transport during monsoon events. Marine aerosol samples were collected between January 2009 and December 2010 at the coastal region of Mersing, which is located in the southern South China Sea and is about 160km northeast of Johor Bahru, as part of the atmosphere-ocean interaction program in Malaysia. About 47 PM10 samples were collected using the Sierra-Andersen model 1200 PM10 sampler over a 2-year sampling campaign between January 2009 and December 2010. Samples were processed using acid digestion sequential extraction techniques to analyze various fractions such as Fe and Mn oxides, organic matter, and residual fractions. While, (210)Pb and (210)Po activities were measured with the Gross Alpha/Beta Counting System model XLB-5 Tennelec® Series 5 and the Alpha Spectrometry (model Alpha Analyst Spectroscopy system with a silicon-surface barrier detector), respectively. The distribution activities of (210)Pb and (210)Po in the PM10 samples were varied from 162 to 881μBq/m(3) with mean value of 347±170μBq/m(3) and from 85 to 1009μBq/m(3) with mean value of 318±202μBq/m(3), respectively. The analysis showed that (210)Po activity in our samples lies in a border and higher range than global distribution values due to contributions from external sources injected to the atmosphere. The speciation of (210)Pb and (210)Po in marine aerosol corresponds to transboundary haze; e.g., biomass burning especially forest fires and long-range air mass transport of terrestrial dust has enriched concentrations of particle mass in the local atmosphere. The monsoon seems to play an important role in transporting terrestrial dust from Indo-China and northern Asia especially during the northeast monsoon, as well as biogenic pollutants originating from Sumatra and the southern ASEAN region during southwest monsoon events.

Identification of hydroxy- and keto-dicarboxylic acids in remote marine aerosols using gas chromatography/quadruple and time-of-flight mass spectrometry.

The identification of hydroxy- and keto-dicarboxylic acids (diacids) in remote marine aerosol samples is important for a better understanding of the composition of organic particulate matter, as this chemical composition is essential for predicting the effects on climate, air quality, and human health. Molecular characterization of these compounds provides insights into sources and formation pathways of organic aerosols. The method of chemical derivatization followed by gas chromatography-flame ionization detection (GC-FID), gas chromatography/quadruple mass spectrometry (GC/QMS) and gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) was used to identify hydroxy- and keto-diacids in remote marine aerosols. Atmospheric samples were collected at Chichijima Island in the western North Pacific and the diacids and related compounds were extracted with organic-free ultrapure water. A two-step derivatization technique was employed, using 14% BF3 /n-butanol for the butylation of carboxyl groups and acidic ketones followed by N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) for the trimethylsilylation of hydroxyl groups. Several new peaks were detected in the gas chromatogram after trimethylsilylation of the dibutyl ester fraction. Based on mass spectral interpretation with authentic standards, we successfully identified and quantified a homologous series of hydroxydiacids, including tartaric and oxaloacetic acids. In addition, transformation of oxaloacetic acid into its enol form was elucidated. Utilizing GC-FID, GC/QMS and GC/TOFMS, hydroxy- and keto-diacids were identified in the remote marine aerosols. A complete structural characterization was achieved with extensive mass spectral analysis. Molecular distributions of hydroxydiacids generally showed the predominance of malic acid followed by tartronic acid. We consider that these hydroxydiacids are important intermediates in the atmospheric oxidation of organic aerosols to result in smaller diacids. Copyright © 2016 John Wiley & Sons, Ltd.

Longitudinal distributions of dicarboxylic acids, ω‐oxoacids, pyruvic acid, α‐dicarbonyls, and fatty acids in the marine aerosols from the central Pacific including equatorial upwelling

AbstractRemote marine aerosol samples (total suspended particles) were collected during a cruise in the central Pacific from Japan to Mexico (1°59′N–35°N and 171°54′E–90°58′W). The aerosol samples were analyzed for dicarboxylic acids (C2–C11), ω‐oxoacids, pyruvic acid, α‐dicarbonyls, and fatty acids as well as organic and elemental carbon, water‐soluble organic carbon, and total nitrogen (WSTN). During the study, diacids were the most abundant compound class followed by fatty acids, ω‐oxoacids, and α‐dicarbonyls. Molecular compositions of diacids showed a predominance of oxalic (C2) acid followed by malonic (C3) and succinic (C4) acids. Oxalic acid comprises 74% of total diacids. This result suggests that photochemical production of oxalic acid is significant over the central Pacific. Spatial distributions of diacids, ω‐oxoacids, pyruvic acid, α‐dicarbonyls, and fatty acids together with total carbon and WSTN showed higher abundances in the eastern equatorial Pacific where the upwelling of high‐nutrient waters followed by high biological productivity is common, indicating that their in situ production is important in the warmer central Pacific through photochemical oxidation from their gaseous and particulate precursors. This study demonstrates that there is a strong linkage in biogeochemical cycles of carbon in the sea‐air interface via ocean upwelling, phytoplankton productivity, sea‐to‐air emissions of organic matter, and formation of secondary organic aerosols in the eastern equatorial Pacific.

Aerosol water soluble organic matter characteristics over the North Atlantic Ocean: Implications for iron-binding ligands and iron solubility

Aerosol water soluble organic carbon (WSOC) and iron (Fe) loadings were examined in aerosols collected during the 2011 US GEOTRACES cruise in the North Atlantic Ocean to explore the feasibility of a role for water soluble organic matter (WSOM) organic complexation in determining the higher fractional solubility of Fe (%FeS) observed in North American-influenced relative to North African-influenced aerosols. Proton nuclear magnetic resonance spectroscopy (1H NMR) was employed to characterize the WSOM, and principal component analysis was then applied to differentiate North American-influenced from North African-influenced aerosol WSOM and provide clues to the molecular identities of organic ligands. As has been found in previous studies, North African-influenced samples had orders of magnitude higher total Fe (FeT) loadings (8.9–101nmol Fe m−3 air) and orders of magnitude lower %FeS (0.12–0.29%) than those found in North American-influenced (FeT: 0.03–1.4nmol Fe m−3 air; %FeS: 0.67–3.62%) and Marine (minimal recent continental influence; FeT: 0.02–0.25nmol Fe m−3 air; %FeS: 1.1–10.7%) samples. Aerosol %FeS values were positively correlated with WSOC/FeT ratios with North American combustion-influenced (39–540) and Marine (30–850) aerosol samples having orders of magnitude more moles of WSOC per mole of FeT than North African (0.42–3.8) aerosol samples. The high WSOC/FeT ratios in the North American combustion-influenced samples suggest a realistic role for organic ligands binding with Fe and accounting for some portion of the higher aerosol %FeS also observed for these samples. Principal component analyses of 1H NMR spectra show North American-influenced aerosol WSOM to have higher contributions from hydrogens in aliphatic carbon chains attached to heteroatomic functional groups such as those in nitrate, amine, ether, ester, and carboxylate compounds compared to North African mineral dust-influenced aerosol WSOM. These multifunctional aliphatic WSOM compounds are suggested as candidate Fe binding ligands to be explored with future work.

Using Raman Microspectroscopy to Determine Chemical Composition and Mixing State of Airborne Marine Aerosols over the Pacific Ocean

Chemical composition and mixing state of aerosols collected over an 11,000 km latitudinal cruise in the Pacific Ocean are reported here as determined by a new application of Raman spectroscopy. The Raman microspectroscopy technique employs a Raman spectrometer coupled to an optical microscope to identify the chemical composition and internal mixing state of single particles. By analyzing multiple particles in a collected ensemble, the degree of external mixing of particles was also determined. To lend context to the Pacific aerosol population sampled, atmospheric aerosol concentration, and the critical supersaturation required for the aerosols to activate as cloud condensation nuclei, and chlorophyll a concentration in the underlying water (a metric for phytoplankton biomass in the ocean) were also obtained. Our results indicate that long chain organic molecules were prevalent in the marine aerosol samples throughout the cruise, including during coastal and open ocean locations, in both hemispheres, and i...