Comment on acp-2022-454

<strong class="journal-contentHeaderColor">Abstract.</strong> Understanding chemical processes leading to the formation of atmospheric aerosol particles is crucial to improve our capabilities in predicting the future climate. However, those mechanisms are still inadequately characterized, especially in polar regions. In this study, we report observations of neutral and charged aerosol precursor molecules and chemical cluster composition (qualitatively and quantitatively), as well as air ions and aerosol particle number concentrations and size distributions from the Marambio research station (64<span class="inline-formula">^∘</span>15<span class="inline-formula">^′</span> S, 56<span class="inline-formula">^∘</span>38<span class="inline-formula">^′</span> W), located north of the Antarctic Peninsula. We conducted measurements during the austral summer, between 15 January and 25 February 2018. The scope of this study is to characterize new particle formation (NPF) event parameters and connect our observations of gas-phase compounds with the formation of secondary aerosols to resolve the nucleation mechanisms at the molecular scale. NPF occurred on 40 % of measurement days. All NPF events were observed during days with high solar radiation, mostly with above-freezing temperatures and with low relative humidity. The averaged formation rate for 3 nm particles (<span class="inline-formula"><i>J</i>₃</span>) was 0.686 cm<span class="inline-formula">^−3</span> s<span class="inline-formula">^−1</span>, and the average particle growth rate (GR<span class="inline-formula">_{3.8–12 nm}</span>) was 4.2 nm h<span class="inline-formula">^−1</span>. Analysis of neutral aerosol precursor molecules showed measurable concentrations of iodic acid (IA), sulfuric acid (SA), and methane sulfonic acid (MSA) throughout the entire measurement period with significant increase in MSA and SA concentrations during NPF events. We highlight SA as a key contributor to NPF processes, while IA and MSA likely only contribute to particle growth. Mechanistically, anion clusters containing ammonia and/or dimethylamine (DMA) and SA were identified, suggesting significant concentration of ammonia and DMA as well. Those species are likely contributing to NPF events since SA alone is not sufficient to explain observed nucleation rates. Here, we provide evidence of the marine origin of the measured chemical precursors and discuss their potential contribution to the aerosol phase.

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.

In general, sediments in nature comprise populations of various diameters. Accurate information regarding the sources and depositional mechanisms of the populations can be obtained through their temporal and spatial comparisons. In this study, the grain size distribution of surface sediments from the Bering Sea and western Arctic Ocean were fitted and partitioned into populations using a log-normal distribution function. The spatial variations in the populations indicate differences in their sources and deposition mechanisms. The sediments on most of the Bering Sea Shelf originated from the Yukon River, and were transported westward by waves and currents. However, the presence of a coarser population outside Anadyr Bay was the result of Anadyr River transport. Additionally, a northward transport trend of fine suspended particles was observed on the west side of the Bering Sea Shelf. The sediments in Hope Valley in the south Chukchi Sea also originated from the Yukon River. The coarser population on the central Chukchi Sea Shelf originated from coast of Alaska to the east, not the Yukon River, and was transported by sea ice and bottom brine water. The populations of sediments from the Chukchi Basin and the base of the Chukchi Sea Slope are the result of sea ice and eddy action. Surface sediments from the western high Arctic Ocean predominantly comprised five populations, and two unique populations with mode diameters of 50–90 µm and 200–400 µm, respectively, were ubiquitous in the glacial and interglacial sediments. It was difficult to distinguish whether these two populations originated from sea ice or icebergs. Therefore, caution should be exercised when using either the > 63 µm or > 250 µm fractions in sediments as a proxy index for iceberg and ice sheet variation in the high Arctic Ocean. Citation: Wang W G, Yang J C, Zhao M W, et al. Spatial variation in grain-size population of surface sediments from northern Bering Sea and western Arctic Ocean: implications for provenance and depositional mechanisms. Adv Polar Sci, 2020, 31(3): 192-204, doi: 10.13679/j.advps.2020.0015

The concentration of methanesulfonic acid (MSA) was determined in a shallow south central Greenland ice core (20D). This study provides a high‐resolution record of the DMS‐derived biogenic sulfur in Greenland precipitation over the past 200 years. The mean concentration of MSA is 3.30 ppb (σ = 2.38 ppb, n = 1134). The general trend of MSA is an increase from 3.01 to 4.10 ppb between 1767 and 1900, followed by a steady decrease to 2.34 ppb at the present time. This trend is in marked contrast to that of non‐sea‐salt sulfate (nss SO42−), which increases dramatically after 1900 due to the input of anthropogenic sulfur. The MSA fraction ((MSA/(MSA + nss SO42−))* 100) ranges from a mean of 15% in preindustrial ice to less than 5% in recent ice. These MSA fractions suggest that approximately 15 to 40% of the sulfur in recent Greenland ice is of biological origin. It is suggested that there is a significant low‐latitude component to the biogenic sulfur in the core and that variations in the MSA fraction reflect changes in the relative strengths of low‐ and high‐latitude inputs. The data show no evidence for a strong dependence of dimethyl sulfide (DMS) emissions on sea surface temperature during the last century. There is also no indication that the yield of MSA from DMS oxidation has been altered by increased NOx levels over the North Atlantic during this period.

Forty‐seven years of week‐long total suspended particle samples from Kevo Finland were analyzed for methane sulfonic acid (MSA) and sulfate. Kevo is located 350 km north of the Arctic Circle. MSA and non‐sea‐salt sulfate (NSS‐SO4) showed clear seasonal trends. MSA peaks from May to July, coinciding with warmer waters and increased biogenic activity in the surrounding seas. NSS‐SO4 peaks in March with a minimum during the summer, the typical pattern for Arctic haze. MSA concentrations were found to be positively correlated (p &lt; 0.001) with sea surface temperature anomalies in the surrounding seas. MSA showed a trend of 0.405 ng/m3/yr (0.680%/yr) for June and July. NSS‐SO4 concentrations at Kevo declined dramatically in the early 1990s, probably as a result of the collapse of the Soviet Union. The decline has continued since the mid‐1990s.

A study on the improvement of deposition rate for near-eutectic PbSn solder plating was performed. This research focused on (1) the effect of process parameters on the diffusion-limited current density (LCD) to extend the operating zone, (2) the process optimization at 4 /spl mu/m/min with a modified bath, and (3) the trouble-shooting procedures for abnormal and non-conformal growths. The effect of waveform on surface morphology, growth pattern, film composition and thickness uniformity was also examined. The LCD was increased by increasing metal concentration, bath temperature and agitation, or by decreasing the concentration of methane sulfonic acid (MSA). The effect of additives on LCD was not significant. No significant change in morphology and growth pattern was observed up to approximately 10 /spl mu/m/min with a modified bath. Process results obtained at optimized conditions showed smooth surfaces, conformal growth and good repeatability of thickness and composition. The probability of abnormal growth was increased with increasing deposition rate, but it was prominently suppressed by increasing MSA concentration and temperature or by decreasing duty cycle. The growth conformality along the resist was improved at a fixed deposition rate by decreasing wafer rotation speed and duty cycle or by increasing MSA concentration.

&amp;lt;p&amp;gt;One way to form aerosol particles is the condensation of oxidized atmospheric trace gases, such as sulfuric acid (SA) into small molecular clusters. After growing to larger particles by condensation of low volatile gases, they can affect the planets climate directly by scattering light and indirectly by acting as cloud condensation nuclei. Observations of low-volatility aerosol precursor gases have been reported around the world but long-term measurement series and Arctic data sets showing seasonal variation are close to non-existent. In here, we present ~7 months of aerosol precursor gas measurements performed with the nitrate based chemical ionization mass spectrometer (CI-APi-TOF). We deployed our measurements ~250 km above the Arctic Circle at the Finnish sub-Arctic field station, SMEAR I in V&amp;amp;#228;rri&amp;amp;#246;. We report concentration measurements of the most common new particle formation related compounds; sulfuric acid, methanesulfonic acid (MSA), iodic acid (IA) and highly oxygenated organic compounds, HOMs. At this remote measurement site, surrounded by a strict nature preserve, that gets occasional pollution from a Russian city of Murmansk, SA is originated both from anthropogenic and biological sources and has a clear diurnal cycle but no significant seasonal variation, while MSA as an oxidation product of purely biogenic sources is showing a more distinct seasonal cycle. Iodic acid concentrations are the most stable throughout the measurement period, showing almost identical peak concentrations for spring, summer and autumn. HOMs are abundant during the summer months and due to their high correlation with ambient air temperature, we suggest that most of HOMs are products of monoterpene oxidation. New particle formation events at SMEAR I happen under relatively low temperatures, low relative humidity, high ozone concentration, high SA concentration in the morning and high MSA concentrations in the afternoon. The role of HOMs in aerosol formation will be discussed. All together, these are the first long term measurements of aerosol forming precursor from the sub-arctic region helping us to understand atmospheric chemical processes and aerosol formation in the rapidly changing Arctic.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;&amp;amp;#160;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;&amp;amp;#160;&amp;lt;/p&amp;gt;

Successful matrix acidizing of carbonate reservoirs depends on the selection of optimal stimulation fluids. Because of the rapid reaction rate and corrosive nature of HCl in downhole conditions, other alternatives are much in demand. Organic acids, particularly methanesulfonic acid (MSA), offer a viable alternative to HCl in terms of being less reactive as well as less corrosive and environmentally benign. However, MSA is expensive. To reduce the cost, this study proposes to use blend of HCl and MSA for carbonate stimulation, while enhancing the properties of HCl. Coreflood studies were performed and the results were compared to those obtained by equivalent concentrations of the individual acids. Three different ratios of HCl and MSA were used to conduct coreflood experiments on 6-in. long Indiana Limestone cores at 250°F. The volume of acid required to reach breakthrough was recorded, and the cores were analyzed using CT scans. Wormhole structures were identified, and their tortuousities were determined. The effluent samples were analyzed for pH, calcium concentration, and unconsumed acid concentration. Coreflood studies indicated that 5:5 wt% HCl:MSA blend was the most suitable candidate for matrix acidizing among the three blends tested (2.5:7.5 and 7.5:2.5 wt% HCl:MSA being the other two blends investigated). At the optimum injection rate of 7.5 cm3/min, both 2.5:7.5 and 5:5 wt% HCl:MSA mixture required lesser pore volumes (PVs) of acid to reach breakthrough, compared to their individual acid controls. A single, straight, and dominant wormhole was observed with no branching and less tortuousity in both the cases. The control experiments with equivalent concentrations of HCl and MSA required higher PVs of acid to reach breakthrough with branching during wormhole propagation. Calcium ion dissolution was least for the 5:5 wt% mixture among the three blends tested. Higher unconsumed acid concentration was noted in case of 5:5 wt% compared to 2.5:7.5 wt% blend, thus promising greater penetration depth with the same PV of acid. On the other hand, the wormhole formed by the acid blend of 7.5:2.5 wt% HCl:MSA required almost the same PV of acid to reach breakthrough as its corresponding HCl control, and it was more enlarged and tortuous than its corresponding MSA control. 5:5 wt% HCl:MSA blend creates deeper wormholes and retards the HCl reaction with the rock matrix. Major advantages rendered by the new acid mixture include: (1) deeper wormholes that will ultimately result in enhanced well productivity, and (2) cost effectiveness in carbonate stimulation compared to standard systems currently used in the market.

Abstract. In this study, we present and analyze the first continuous time series of relevant aerosol precursor vapors from the central Arctic (north of 80° N) during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. These precursor vapors include sulfuric acid (SA), methanesulfonic acid (MSA), and iodic acid (IA). We use FLEXPART simulations, inverse modeling, sulfur dioxide (SO2) mixing ratios, and chlorophyll a (chl a) observations to interpret the seasonal variability in the vapor concentrations and identify dominant sources. Our results show that both natural and anthropogenic sources are relevant for the concentrations of SA in the Arctic, but anthropogenic sources associated with Arctic haze are the most prevalent. MSA concentrations are an order of magnitude higher during polar day than during polar night due to seasonal changes in biological activity. Peak MSA concentrations were observed in May, which corresponds with the timing of the annual peak in chl a concentrations north of 75° N. IA concentrations exhibit two distinct peaks during the year, namely a dominant peak in spring and a secondary peak in autumn, suggesting that seasonal IA concentrations depend on both solar radiation and sea ice conditions. In general, the seasonal cycles of SA, MSA, and IA in the central Arctic Ocean are related to sea ice conditions, and we expect that changes in the Arctic environment will affect the concentrations of these vapors in the future. The magnitude of these changes and the subsequent influence on aerosol processes remains uncertain, highlighting the need for continued observations of these precursor vapors in the Arctic.

The minimum brightness temperature (mBT) of seawater in the polar region is an important parameter in algorithms for determining sea ice concentration or snow depth. To estimate the mBT of seawater at 6.925 GHz for the Arctic and Antarctic Oceans and to find their physical characteristics, we collected brightness temperature and sea ice concentration data from the Advanced Microwave Scanning Radiometer 2 (AMSR2) for eight years from 2012 to 2020. The estimated mBT shows constant annual values, but we found a significant difference in the seasonal variability between the Arctic and Antarctic Oceans. We calculated the mBT with the radiative transfer model parameterized by sea surface temperature (SST), sea surface wind speed (SSW), and integrated water vapor (IWV) and compared them with our observations. The estimated mBT represents the modeled mBT emitted from seawater under conditions of 2–5 m/s SSW and SST below 0 °C, except in the Arctic summer. The exceptional summer mBT in the Arctic Ocean was related to unusually high SST. We found evidence of Arctic amplification in the seasonal variability of Arctic mBT.

Oxygen evolution on alpha-lead dioxide electrodes in methanesulfonic acid

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.

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.

How will the opening of the Northern Sea Route influence the Suez Canal Route? An empirical analysis with discrete choice models

Size‐segregated aerosol samples were collected over the western North Pacific in summer 2008 to investigate marine biological contribution to organic aerosols. The samples were analyzed for organic carbon (OC), water‐soluble organic carbon (WSOC), and water‐soluble organic compounds including diacids (C2–C9), ω‐oxocarboxylic acids, and α‐dicarbonyls as well as methanesulfonic acid (MSA). The average concentrations of OC and oxalic acid (C2) were approximately two to three times larger in marine biologically more influenced aerosols, defined by the concentrations of MSA and azelaic acid (C9), than in less influenced aerosols. WSOC, which showed a statistically significant correlation with MSA, accounted for 15–21% of total mass of the components determined in the submicrometer range of biologically more influenced aerosols. These values are comparable to those of water‐insoluble organic carbon (WIOC) (∼14–23%), suggesting that organic aerosols in this region are enriched in secondary organic aerosols (SOA) linked to oceanic biological activity. In these aerosols, substantial fractions of C2–C4 diacids were found in the submicrometer size range. Positive correlations of oxalic acid with C3–C5 diacids and glyoxylic acid suggest that secondary production of oxalic acid occurs possibly in the aqueous aerosol phase via the oxidation of longer‐chain diacids and glyoxylic acid in the oceanic region with higher biological productivity. We found similar concentration levels and size distributions of methylglyoxal between the two types of aerosols, suggesting that formation of oxalic acid via the oxidation of methylglyoxal from marine isoprene is insignificant in the study region.