Methanesulfonic Acid Concentrations Research Articles

Compositions and Structures of Methanesulfonic Acid Complexes with Acetonitrile According to IR Spectroscopic Data

IR spectra of solutions of methanesulfonic acid in acetonitrile are recorded and analyzed at 30°C at methanesulfonic acid concentrations ranging from 0 to 100%. Molecular 1 : 1 complexes with the coordination of the acid proton at the nitrogen atom of the acetonitrile molecule are formed over a wide range of acid concentrations. When the base is in excess, the whole amount of the acid is bound in these complexes. In solutions with excess acid, the solvation of the 1 : 1 complexes by several methanesulfonic acid molecules produces associates containing a structure fragment in which the acetonitrile molecule acts as both the donor and acceptor of hydrogen bonds. Hydrogen bonds involving CH3 groups of acetonitrile can be formed when the 1 : 1 complexes are solvated by several acid molecules.

Properties of aqueous methanesulfonic acid: complex index of refraction and surface tension.

The complex index of refraction of aqueous methanesulfonic acid (MSA) at room temperature and at concentrations of 1-70 wt. % is presented. The complex index of refraction is obtained in the entire wave-number region from the mid infrared to the ultraviolet-visible regions. An analysis of the infrared spectra reveals a single absorption band, which makes it possible to identify MSA in aqueous H2SO4. The surface tension of 1-99-wt. % aqueous MSA from room temperature to approximately 263 K, depending on the concentration of MSA, is reported. A polynomial parameterization of the surface tension in terms of acid weight fraction and temperature is presented.

Biogenic emission of dimethylsulfide from a highly eutrophicated coastal region, Masan Bay, South Korea

Abstract Atmospheric dimethylsulfide (DMS), water-soluble ionic species in aerosol such as non-seasalt sulfate and methanesulfonic acid (MSA), and seawater DMS were measured in highly eutrophicated Masan Bay, Korea in July–August 1997. Mean (median) concentrations of atmospheric DMS, seawater DMS, non-seasalt sulfate, and MSA during the experiment were 188 pptv (49 pptv), 6.3 nM (5.3 nM), 3.0 μg m −3 (2.3 μg m −3 ), and 0.010 μg m −3 (0.008 μg m −3 ), respectively. The vertical profiles of seawater, especially in inner bay, reveal that DMS concentrations were enhanced near the bottom coincidently with extremely low levels of chlorophyll- a and depleted oxygen. There were several episodes of high DMS mixing ratios up to a few ppbv, which was associated with strong wind and elevated DMS but very low chlorophyll- a and relatively low dissolved oxygen contents in the surface water. It indicates that DMS accumulated in anoxic bottom water was often transferred to the overlying water column, consequently leading to elevated DMS in the atmosphere. The mean (median) molar ratio of MSA to non-seasalt sulfate was 0.41% (0.30%), which implies the major contribution of anthropogenic SO 2 to sulfur budget in the study area. The median flux of DMS from sea to air was estimated to 3.2 μm m −2 d −1 .

A novel flow battery: A lead acid battery based on an electrolyte with soluble lead(ii)

This series of papers will describe the chemistry, electrochemistry and performance of a flow battery with no separator and a single electrolyte, lead(II) in methanesulfonic acid. Voltammetry at rotating disc electrodes is used to define the conditions for the high rate deposition and dissolution of lead and lead dioxide in aqueous methanesulfonic acid. The determination of lead methanesulfonate solubility and solution conductivity as a function of lead methanesulfonate and methanesulfonic acid concentrations was carried out in order to aid the selection of the electrolyte for the battery.

Seed layer corrosion of damascene structures in copper sulfonate electrolytes

The influence of sulfonic acid concentrations in copper methanesulfonate, Cu(CH 3SO 3) 2:CH 3SO 3H, plating solutions on the stability of a 1000 Å seed layer in Damascene structures is presented. Immersion of a seeded wafer into the plating solutions shows little tendency to corrode up to 3600 s. Anodic current density steps initiate seed layer corrosion resulting in exposure of the underlying TaN barrier layer. Large current density steps (>300 μA cm −2) or high free methanesulfonic acid concentration causes a slightly more rapid dissolution of the seed layer. The anodic dissolution efficiency is greater than 100% indicating chemical dissolution of copper is slow leading to a stable seed layer in these media.

Highlights of OH, H2SO4, and methane sulfonic acid measurements made aboard the NASA P‐3B during Transport and Chemical Evolution over the Pacific

Measurements of hydroxyl radical (OH), sulfuric acid (H2SO4), and methane sulfonic acid (MSA) were performed aboard the NASA P‐3B using the selected ion chemical ionization mass spectrometry technique during the Transport and Chemical Evolution over the Pacific (TRACE‐P) study. Photochemical box model calculations of OH concentrations yielded generally good agreement with an overall tendency to overestimate the measured OH by ∼20%. Further analysis reveals that this overestimation is present only at altitudes greater than ∼1.5 km, with the model underestimating OH measurements at lower altitudes. Boundary layer H2SO4 measurements, performed in a volcanic plume off the southern coast of Japan, revealed some of the largest marine boundary layer H2SO4 concentrations ever observed and were accompanied by new particle formation. Nighttime measurements of OH, H2SO4, and MSA in the remote pacific off Midway Island revealed significant boundary layer concentrations of H2SO4 and MSA, indicating evidence of nighttime boundary layer oxidation processes but in the absence of OH. A cursory exploration of the sources of production of the H2SO4 and MSA observed at night is presented.

Measurement of Halogenated Dicarboxylic Acids in the Arctic Aerosols at Polar Sunrise

Halogenated dicarboxylic acids, such as bromomalonic (Br-C3), chlorosuccinic (Cl-C4) and bromosuccinic (Br-C4) acids, have been measured, for the first time, in the arctic aerosols during the polar sunrise experiment ALERT2000 (February to May). They were detected in the light spring, but not in the dark winter. Concentration ranges of halogenated diacids in the spring were 0.11–0.68 ng m−3 for Br-C3 diacid, 0.04–0.10 ng m−3 for Cl-C4 diacid and 0.12–0.20 ng m−3 for Br-C4 diacid. Those of Br-C3 diacid increased from late April to early May, whereas Cl-C4 diacid decreased. In contrast, Br-C4 diacid showed maximum concentrations in the middle of the experiment. A strong negative correlation (R = −0.98) was obtained between Br-C3 and Cl-C4 diacids. Concentrations of methanesulfonic acid (MSA) also increased from late April to early May whereas those of Cl− ion decreased. A strong positive correlation was found between Cl-C4 diacid and Cl− ion (R = 0.99) and between Br-C3 diacid and MSA (R = 0.96). These results suggest that Br-C3 diacid is primarily derived from marine biogenic source, whereas Cl-C4 diacid is secondarily formed by heterogeneous reaction involving halogen chemistry on sea salt. Satellite images of sea ice concentrations and backward air mass trajectories suggest that the aerosols containing halogenated diacids were transported over the sampling sites from the Arctic Ocean covered with sea ice.

The sulfur cycle at high‐southern latitudes in the LMD‐ZT General Circulation Model

This modeling study was motivated by the recent publication of year‐round records of dimethylsulfide (DMS) and dimethylsulfoxide (DMSO) in Antarctica, completing the available series of sulfate and methanesulfonic acid (MSA). Sulfur chemistry has been incorporated in the Laboratoire de Météorologie Dynamique‐Zoom Tracers (LMD‐ZT) Atmospheric General Circulation Model (AGCM), with high‐resolution and improved physics at high‐southern latitudes. The model predicts the concentration of six major sulfur species through emissions, transport, wet and dry deposition, and chemistry in both gas and aqueous phases. Model results are broadly realistic when compared with measurements in air and snow or ice, as well as to results of other modeling studies, at high‐ and middle‐southern latitudes. Atmospheric MSA concentrations are underestimated and DMSO concentrations are overestimated in summer, reflecting the lack of a DMSO heterogeneous sink leading to MSA. Experiments with various recently published estimates of the rate of this sink are reported. Although not corrected in this work, other defects are identified and discussed: DMS concentrations are underestimated in winter, MSA and non‐sea‐salt (nss) sulfate concentrations may be underestimated at the South Pole, the deposition scheme used in the model may not be adapted to polar regions, and the model does not adequately reproduces interannual variability. Oceanic DMS sources have a major contribution to the variability of sulfur in these regions. The model results suggest that in a large part of central Antarctica ground‐level atmospheric DMS concentrations are larger in winter than in summer. At high‐southern latitudes, high loads of DMS and DMSO are found and the main chemical sink of sulfur dioxide (SO2) is aqueous oxidation by ozone (O3), whereas oxidation by hydrogen peroxide (H2O2) dominates at the global scale. A comprehensive modeled sulfur budget of Antarctica is provided.

Gas‐aerosol relationships of H2SO4, MSA, and OH: Observations in the coastal marine boundary layer at Mace Head, Ireland

Atmospheric concentrations of gaseous sulfuric acid (H2SO4), methane sulfonic acid (MSA), and hydroxyl radicals (OH) were measured by chemical ionization mass spectrometry (CIMS) during the second New Particle Formation and Fate in the Coastal Environment (PARFORCE) campaign in June 1999 at Mace Head, Ireland. Overall median concentrations in marine background air were 1.5, 1.2, and 0.12 × 106 cm−3, respectively. H2SO4 was also present at night indicating significant contributions from nonphotochemical sources. A strong correlation was found between daytime OH and H2SO4 levels in clean marine air suggesting a fast local production of H2SO4 from sulfur precursor gases. Steady state balance calculations of ambient H2SO4 levels agreed with measured concentrations if either very low H2SO4 sticking coefficients (0.02–0.03) or sources in addition to the SO2 + OH reaction were assumed. Overall, variations in ambient H2SO4 levels showed no correlation with either the tidal cycle or ultrafine particle (UFP) concentrations. However, on particular days an anticorrelation between H2SO4 and UFP levels was occasionally observed providing evidence for the contribution of H2SO4 to new particle formation and/or particle growth. Gaseous MSA concentrations were inversely correlated with dew point temperature reflecting a highly sensitive gas‐particle partitioning equilibrium of this compound. The present observations seriously question the general use of MSA as a conservative tracer to infer the relative production yield of H2SO4 from dimethylsulfide (DMS) oxidation. MSA/H2SO4 concentration ratios typically ranged between 0.06 and 1.0 in marine air at ground level. Measured diel OH profiles showed a significant deviation from concurrent variations of the ozone photolysis frequency. They also showed up to 1 order of magnitude lower values compared to OH concentrations calculated with a simple photochemical box model. These differences were most pronounced during particle nucleation events occurring on sunny days around noon and at low tide. The present results suggest that both the oxidation capacity and the particle formation potential in the coastal boundary layer were significantly affected by reactions of unknown compounds prevailing in this type of environment.

Chemical Assessment of Oceanic and Terrestrial Sulfur in the Marine Boundary Layer over the Northern North Pacific during Summer

Dimethylsulfide (DMS) in surface seawater and the air, methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO4 2−) in aerosol, and radon-222 (Rn-222) were measured in the northern North Pacific, including the Bering Sea, during summer (13 July – 6 September 1997). The mean atmospheric DMS concentrations in the eastern region (21.0 ± 5.8 nmole/m3 (mean ± S.D.), n=30) and Bering Sea (19.9 ± 9.8 nmole/m3, n=10) were higher than that in the western region (11.1 ± 6.4 nmole/m3, n=31) (p<0.05), although these regions did not significantly differ in the mean DMS concentration in surface seawater. Mean sea-to-air DMS flux in the eastern region (21.0 ± 10.4 μ mole/m2/day, n=19) was larger than those in the western region (11.3 ± 16.9 μ mole /m2/day, n=22) and Bering Sea (11.2 ± 7.8 μ mole/m2/day, n=7) (p<0.05). This suggests that the longitudinal difference in atmospheric DMS was produced by that in DMS flux owing to wind speed, while the possible causes of the higher DMS concentrations in the Bering Sea include (1) later DMS oxidation rates, (2) lower heights of the marine boundary layer, and (3) more inactive convection. The mean MSA concentrations in the eastern region (1.18 ± 0.84 nmole/m3, n=35) and Bering Sea (1.17 ± 0.87 nmole/m3, n=13) were higher than that in the western region (0.49 ± 0.25 nmole/m3, n=28) (p < 0.05). Thus the distribution of MSA was similar to that of DMS, while the nss-SO4 2− concentrations were higher near the continent. This suggests that nss-SO4 2− concentrations were regionally influenced by anthropogenic sulfur input, because the distribution of nss-SO4 2− was similar to that of Rn-222 used as a tracer of continental air masses.

Seasonal variation of dimethylsulfide in the gas phase and of methanesulfonate and non-sea-salt sulfate in the aerosols phase in the Eastern Mediterranean atmosphere

The seasonal variation of gaseous dimethylsulfide (DMS) and its oxidation products (non-sea-salt sulfate (nss-SO 4 2−) and methanesulfonic acid (MSA) have been investigated at a remote coastal location in the Eastern Mediterranean. Daytime atmospheric DMS concentrations were measured in the range 0.3–8.9 nmol m −3 (with an average of 2.35±1.38 nmol m −3, 1 σ uncertainty) and present a well distinguished seasonal cycle with higher values in summer. The seasonal variation of atmospheric DMS is in line with that of seawater DMS concurrently measured in the Cretan Sea. Monthly atmospheric DMS concentrations are significantly correlated with sea-surface temperature. By the mean of a 0-D model based on atmospheric DMS observations, the DMS flux calculated for spring and summer is in reasonable agreement with the fluxes deduced from the seawater DMS data and the wind speed. The diurnal variation of atmospheric DMS was investigated during a 4-day intensive campaign in September 1997 and shows a nighttime minimum, which could be explained by the presence of NO 3 radicals, which are highly reactive towards DMS. Aerosol MSA concentrations varied seasonally from below detection limit (0.04) to 0.99 (average of 0.27±0.15 nmol m −3, 1 σ uncertainty). Similarly aerosol nss-SO 4 2− varied from 0.6 to 123.9 (average of 41.0±17.4 nmol m −3, 1 σ uncertainty). Based on the measured MSA, nss-SO 4 2− and their ratio, the biogenic contribution to nss-SO 4 2− was found to exhibit a well-established seasonal pattern ranging from 1% during winter to 17% during summer.

RECOVERY OF NICKEL VIA LIQUID EMULSION MEMBRANE PROCESS USING METHANE SULFONIC ACID AS A STRIPPANT

A liquid emulsion membrane (LEM) process is considered for the enrichment of nickel ions from dilute aqueous solutions. The liquid emulsion membrane consisted of a carrier di-2 ethylhexyl phosphoric acid (D2EHPA), an organic diluent, an emulsifying agent, and an aqueous stripping agent thereby having water in oil emulsion. Various stripping agents (hydrochloric, sulfuric, nitric, and methane sulfonic acid) were tested for the stability of membrane. The swelling, breakage, osmotic pressure, and particle size of LEM containing various stripping acids were compared. Methane sulfonic acid (MSA) outperformed the other acids as a stripping agent. The recovery of nickel depends on pH of aqueous feed phase. The other important variables affecting the LEM process of nickel such as acid strength, speed of agitation, organic diluent, and treat ratio were systematically investigated by using methane sulfonic acid as a strippant. It was found that nickel extraction was maximum when concentration of MSA was 1M and treat ratio was 1:3. It was also observed that dodecane as a diluent resulted in better extraction of nickel as compared to other diluents such as heptane, toluene, and xylene.

Influence of aromatic reactants and products involved in the two stage electrochemical oxidation on the voltammetric behaviour of Ce(IV)/Ce(III) redox couple

The redox behaviour of the Ce(IV)/Ce(III) couple in 1.0 M nitric acid, 1.0 M sulfuric acid, 1.0 M perchloric acid and in different concentrations of methane sulfonic acid was investigated on a glassy carbon electrode using cyclic voltammetry. Quasi reversible redox behaviour with low ΔEp value of 200 mV and below were observed in 1.0 M sulfuric acid and high concentrations of methane sulfonic acid. Anionic complexes apparently exist in this media. The reactants and products involved in the indirect oxidations are found to influence cerous/ceric redox behaviour in 2.0 M methane sulfonic acid in three distinct ways: (i) in the presence of cerous methane sulfonate organic compounds such as toluene, benzaldehyde and naphthaquinone do not exhibit substantial inhibitive effects; (ii) compounds such as p-xylene and p-tolualdehyde exhibit some inhibitive effect at higher concentrations; and (iii) compounds like naphthalene, p-ethoxy toluene and p-ethoxy benzaldehyde exhibit a fairly high level of inhibitive effect.

Chemical composition of aerosol during particle formation events in boreal forest

Size-segregated chemical aerosol analysis of a total 5 integrated samples has been performed for the atmospheric aerosol during events of new particle formation. The experiments were conducted during the BIOFOR 3 measurement campaign at a boreal forest site in southern Finland in spring 1999. Aerosol samples collected by a cascade low-pressure impactor were taken selectively to distinguish particle formation event aerosol from non-event aerosol. The division into “event” and “non-event” cases was done “in situ” at field, based on the on-line submicron number size distribution. The results on the chemical ionic composition of the particles show only small differences between the event and non-event sample sets. The event samples show lower concentrations of total sulfate and ammonium as well as light dicarboxylic acids such as oxalate, malonate and succinate. In the event samples, nucleation mode particle MSA (methanesulphonic acid) was found to be present exceeding the concentrations found in the non-event samples, but at larger particle sizes the sample sets contained rather similar concentrations of MSA. The most significant difference between the event and non-event sets was found for dimethylammonium, ionic component of dimethylamine ((CH3)2NH), which seems to be present in the particle phase during the particle formation periods and/or during the subsequent particle growth. The absolute event sample dimethylamine concentrations were more than 30-fold greater than the non-event concentrations in the accumulation mode size range. On the other hand, the non-event back-up filter stage for sub-30 nm particles contained more dimethylamine than the event samples. This fractionation is probably a condensation artifact of the impactor sampling. A simple mass balance estimate is performed to evaluate the quality and consistency of the results for the overall mass concentration.

Methanesulfonic acid in a Svalbard Ice Core as an indicator of ocean climate

Methanesulfonic acid (MSA) is an atmospheric oxidation product of dimethyl sulfide, produced by marine biota. MSA preserved in a Svalbard glacier between 1920 and 1996 is compared with the sea surface temperature (SST) and sea‐ice extent of the surrounding ocean over the same period. On decadal timescales high MSA concentrations are found to be associated with warm SST and reduced sea‐ice extent. MSA appears to be influenced by climatic changes related to variations in the import of warm Atlantic Water to the Barents Sea. Atlantic Water plays an important role in the Arctic climate system, therefore MSA concentrations may indirectly reflect larger‐scale changes in the region and may be useful as a proxy for past climate.

Sulfur-containing species in a snow pit in the Lambert Glacier basin, East Antarctica

AbstractA 2.7 m snow pit was sampled in the Lambert Glacier basin, about 650 km from the coast. Concentrations of methanesulfonic acid (MSA) and non-sea-salt SO42- (nssSO42-) show distinct variation with depth in the snow pit. The seasonal variation of MSA is used to date the snow-pit samples. MSA concentration is in the range 1.922.0 μgkg−1 with a mean of 7.0 μgkg-1. The mean nssSO42- concentration is 41.5 μgkg−1 with a range of 0-87 μgkg−1. The nssSO42- ∼ concentration was calculated by subtracting the sea-salt sulfate contribution using Nai as a conservative tracer. The nssSO42– contributes about 80% of the total sulfate in the snow pit. The mean mass ratio of MSA to nssSO42- 0.176, is much higher than that measured in the low to mid-latitudes, but is very close to the ratio in snow at the South Pole. El Chichon and Hudson volcanic eruptions do not significantly perturb the nssS042- concentrations at this site. MSA concentrations are anticorrelated with sea-ice area for the South Indian Ocean sector between 40° and 90° E, suggesting enhanced MSA production accompanying low sea-ice coverage.

Methane sulfonic acid to non‐sea‐salt sulfate ratio in coastal Antarctic aerosol and surface snow

Multiple‐year time series of the weight ratio R of methane sulfonic acid (MSA) to non‐sea‐salt sulfate (nss SO4) in aerosols collected at three coastal Antarctic stations Neumayer (70°39′S, 8°15′W), Halley (75°35′S, 26°19′W), and Dumont D'Urville (66°40′S, 140°1′E) are presented here. Discarding the November 1991 to October 1992 time period, during which the Antarctic atmosphere is thought to have been contaminated by volcanic plumes (Pinatubo and Cerro Hudson), the multiple‐year data sets indicate mean annual R values of 17.9 ± 10.7% at Neumayer (1983–1995) and 11.7 ± 6.7% at Dumont D'Urville (1991–1996). On the basis of a more limited time series (February 1991/February 1992), which partly overlaps the volcanic time period, the Halley data had R values of 25.6 ± 11.9% from October to April. The R seasonal variations are broadly consistent at the three sites, with maxima in mid to late summer (from December to April) ranging from 18.2 ± 4.6% at Dumont d'Urville to 29.2 ± 6.5% at Neumayer and 32.2 ± 6.9% at Halley. Minima are lower than 10% during winter (from May to September) at Neumayer (8.5 ± 2.5%) and Dumont d'Urville (6.0 ± 3.0%). The interpretation of these R values in terms of relative abundance of MSA and nss SO4 produced by the oxidation of dimethylsulfide (DMS) at high southern latitudes is not straighforward. In winter, nss sulfate present at coastal Antarctic sites is likely originating in long‐range transported by‐products from marine DMS emissions taking place at 50°S and non‐DMS sulfate from the continental free troposphere. Midwinter R values show a mean ratio of up to 20% for the pure marine input. From September to November, both MSA and nss sulfate concentrations increase in relation to enhanced marine DMS emissions from 50° to 60°S. R values are only weakly enhanced. In summer, the further increase of MSA and nss sulfate concentrations is related to increased biogenic activity south of 60°S and is characterized by R values in the range of 25 to 35%. The mean ratio for DMS marine emissions south of 60°S is close to 62% at Neumayer and 32 to 38% at Dumont d'Urville. These baseline data obtained at coastal Antarctic sites allow us to investigate the role of various parameters that modulate seasonal variations of R at high southern latitudes including the oxidative capacity of the atmosphere, the temperature of the atmospheric oxidation of DMS, and the aging of marine air masses during their transport from source regions toward coastal Antarctic regions.

Changes in climate, ocean and ice-sheet conditions in the Ross embayment, Antarctica, at 6 ka

Evidence from the Ross embayment, Antarctica, suggests an abrupt cooling and a concomitant increase in sea-ice cover at about 6000 BP (6 ka). Stable-isotope (δD) concentrations in the Taylor Dome ice core, at the western edge of the Ross embayment, decline rapidly after 6 ka, and continue to decline through the late Holocene. Methanesulfonic acid concentrations at Taylor Dome show opposite trends to δD Sediment cores from the western Ross Sea show a percentage minimum for the sea-ice diatom Fragilariopsis curta between 9 and 6 ka, whenTaylor Dome δD values are highest, followed by an increase through the late Holocene. Radiocarbon dates from raised beach deposits indicate that the retreat of ice shelves in the Ross embayment ceased at about 6 ka, coincident with the environmental changes inferred from the sediment and ice-core records. The similarity in timing suggests an important role for climate in controlling the evolution of ice-shelf margins following the end of the last glaciation.

Dimethylsulfide chemistry in the remote marine atmosphere: Evaluation and sensitivity analysis of available mechanisms

A box model of the marine boundary layer is used to simulate the oxidation products of dimethylsulfide, including non‐sea‐salt (nss) sulfate, sulfur dioxide (SO2), methane sulfonic acid (MSA), dimethylsulfoxide (DMSO), methane sulfinic acid (MSEA), and dimethylsulfone (DMSO2). The gas phase oxidation schemes of Yin et al. [1990], Koga and Tanaka [1993], Hertel et al. [1994], Pham et al. [1995], and Benkovitz et al. [1994] are compared with field measurements using nine scenarios. Heterogeneous oxidation of SO2 in cloud droplets and sea‐salt particles is also simulated. A sensitivity analysis is performed to evaluate which atmospheric parameters require the greatest attention in future field studies. Results indicate that the variations among the gas phase mechanisms are small with the parameterized mechanisms performing as accurately as the comprehensive ones. Among the nine scenarios tested, nss‐sulfate is predicted without bias. Predicted MSA and SO2 concentrations depend more on the gas phase mechanism, with the mechanisms tending to underpredict SO2 concentrations. Compared to differences in MSA and SO2 predictions, DMSO, MSEA, and DMSO2 predictions by the various mechanisms are similar. Sulfate predictions are sensitive to the uncertain parameterizations of heterogeneous processes. The interaction of the marine boundary layer with the free troposphere can explain much of the discrepancy between the model predictions and measurements.

Atmospheric dimethylsulfide and sulfur species in aerosol and rainwater at a coastal site in New Zealand

Aspects of the atmospheric speciation of sulfur were investigated at a coastal site on the North Island of New Zealand between December 1990 and November 1992. Gaseous dimethylsulfide (DMS) as well as methanesulfonic acid (MSA) and non‐sea‐salt sulfate (NSSS) in aerosol and rainwater samples were determined. Atmospheric DMS concentrations exhibited seasonal variations in the range 0.25 nmole m−3 to 14.9 nmole m−3, with a median of 3.75 nmole m−3. Also, DMS levels varied diurnally and with meteorological variables such as wind speed and cloud coverage. Aerosol MSA concentrations similarly ranged seasonally from 0.02 to 1.40 nmole m−3 (median 0.36 nmole m−3). Aerosol NSSS concentrations varied from −1.04 to 15.9 nmole m−3, with a median value of 7.92 nmole m−3. MSA and NSSS concentrations in “clean” rainwater samples ranged from 0.03 to 0.31 μeq L−1 (median 0.04 μeq L−1) and 0.83 to 5.44 μeq L−1 (median 1.37 μeq L−1), respectively. The MSA:NSSS molar ratios varied seasonally from 0.44 to 21.4% (median 3.28%) in aerosols of marine character and from 2.38 to 22.3% (median 6.40%) for rainwater samples. Atmospheric DMS and MSA concentrations at this coastal location in New Zealand are comparable to those observed at other remote southern hemisphere sites. In contrast, NSSS concentrations are somewhat elevated, possibly incorporating an unknown contribution from heterogeneous SO2 oxidation. With respect to DMS flux calculations an oceanic emission rate of 83 mg S m−2 yr−1 would be required to account for oxidative losses (70 mg S m−2 yr−1) and leakage out of the marine boundary layer. The sum of wet and dry deposition for MSA and NSSS amounts to 65 mg S m−2 yr−1. The small difference between DMS oxidative losses and total MSA + NSSS deposition likely stems from an underestimate of the wet deposition rate for NSSS.