Sea Salt Sulfate Research Articles

Nitrogen deposition to the eastern Atlantic Ocean. The importance of south-easterly flow

Converting measured concentrations into fluxes and using estimates of biological productivity in the coastal waters of the eastern Atlantic Ocean enables us to determine the role of the atmosphere as a source of biologically essential species, including nitrate and ammonium, to the marine biota. To understand the effects of the atmosphere as a source of nitrogen capable of promoting new production, we need to know both the seasonality of the input as well as the effects of extreme high deposition events which, while small in overall annual budget terms, maybe able to extend, or even promote, phytoplankton growth under nutrient depleted summer conditions. Aerosols and rainwater were collected at both Mace Head and at sea aboard RRS Challenger. Temporal patterns have been interpreted using airmass back trajectories which give the predicted air path prior to arrival at the sampling site. Low levels of both nitrate and ammonium are seen associated with marine westerly flow across the Atlantic and northerly air originating in the Arctic region. As expected, marine derived sodium, chloride, magnesium and seasalt sulphate are high during these periods. High concentration nitrate and ammonium events are seen associated with south-easterly flow where the airmass passes over the UK and northern Europe prior to arrival on the west coast of Ireland. In the polluted atmosphere, nitrate exists as nitric acid and as fine mode (μ1 ¼m diameter) ammonium nitrate aerosol. In the coastal zone, nitric acid reacts with coarse mode seasalt aerosols to form coarse mode (>1 μm diameter) sodium nitrate: HNO3 (g) + NaCl(s) → NaNO3(s) + HCl(g). This seasalt displacement reaction not only enhances dry nitrate deposition through more efficient gravitational settling of large particles, but also increases the efficiency of precipitational scavenging via inertial impaction. By looking at the size distribution of nitrate, we can see evidence for the seasalt displacement reaction. Under the polluted south-easterly flow, ~40-60% of the nitrate occurs in the coarse mode fraction. Under clean marine conditions, the seasalt displacement reaction results in almost complete conversion of nitrate from the fine to the coarse aerosol mode. By converting measured wet and dry nitrate, ammonium and organic nitrogen concentrations into fluxes and comparing the data with estimates of biological productivity in the surface waters, our data suggest that ˜30% of new production in eastern Atlantic surface waters off Ireland can be supported by atmospheric inputs in May 1997 and that most of the input occurs during short lived, high-concentration, south-easterly transport events.

Tracing sources of atmospheric sulphur using epiphytic lichens

The overall objective of this work was to measure the spatial variation of sulphur isotopic composition of lichens across the island of Newfoundland in order to assess the degree to which the atmosphere is being affected by long-range transport of anthropogenic sulphur from eastern North America, and/or local pollution sources. A contour map (based on over 80 composite samples of the lichen Alectoria sarmentosa) illustrates the spatial distribution of sulphur isotopic composition of the Newfoundland atmosphere. It shows a gradient of δ34S of sulphur in lichen, decreasing from the coast to the interior of the island. It also shows local anomalies corresponding to the city of St. John's, the Come-By-Chance Oil Refinery, mining areas and fossil-fuel powered pulp and paper mills in central and western Newfoundland. The study strongly suggests that the isotopic composition of sulphur in the Newfoundland atmosphere is influenced more by the ocean (sea salt sulphate) and local anthropogenic activities in the province, than by long-range transport of continental North American sulphate.

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.

Summertime characteristics of aerosol composition at Cheju Island, Korea

To understand the characteristics of air quality during summer in Northeastern Asia, an intensive field study had been carried out at Cheju Island, Korea during the period of 20 July to 10 August 1994. Total suspended particles and PM 2.5 particles were collected and their mass and ion concentrations were analyzed. Along with PM 2.5, gaseous species were collected on impregnated filters. Also, another low volume sampler collected carbonaceous species analysis. The sampling period could be classified into two distinctive periods, with a highly polluted period between 20 July and 1 August and an unpolluted period between 2 and 10 August. During the polluted period, the mean non sea-salt sulfate concentrations in TSP and PM 2.5 were 16.6 and 13.4 μg m -3, respectively. Backward trajectory analysis showed that air parcels arriving at the sampling site during the former period were mainly from Korea and Japan while air parcels during the latter period were from the North Pacific Ocean. It was suggested that the air pollutant levels during the latter period could be considered as marine background concentrations in the region during summer.

Field measurements of dimethyl sulphide and its oxidation products in the atmosphere

Dimethyl sulphide (DMS) is released into ocean waters by phytoplankton and may then cross the water–air interface into the atmosphere. Various models have been formulated to describe its behaviour in the atmosphere. Here, measurements of its concentrations and those of its major oxidation products, methane sulphonate, sulphur dioxide, non sea–salt sulphate and demethyl sulphoxide, in both the gas and aerosol phases, in Atlandtic air, are used to validate these qualitative descriptions of its oxidation. Behaviour consistent with day–time oxidation by the hydroxyl radical, with the yield of methane sulphonic acid being both temperature dependent and under the influence of the nitrogen dioxide mixing ratio, is seen. The rapid production of new particles also seems likely under certain conditions but it is not clear whether or not they enhance the concentrations of cloud condensation nuclei in the maritime troposphere. In maritime air a substantial fraction of the sulphate formed appears to be neutralized by reaction with ammonia to form ammonium aerosol.

Dimethylsulfide oxidation and the ratio of methanesulfonate to non sea-salt sulfate in the marine aerosol

A box model of DMS oxidation in the clean, low-NO x marine atmospheric boundary layer has been used to predict the latitude dependence of the aerosol methanesulfonate to non sea-salt sulfate ratio. The observed latitude dependence of this ratio in the Southern Hemisphere can be reproduced reasonably well if the full suite of reactions proposed by Yin et al. (1990a) is employed, and a strong temperature dependence is specified in the rates of decomposition of CH3SO2 and CH3SO3 radicals.

Wet deposition at the sub-20 km scale in a rural upland area of England

A network of 10 bulk precipitation collectors was established in an upland region of northern England to examine the small-scale variability of precipitation composition in a rural area. Significant spatial variability was shown for non sea-salt sulphate, calcium and hydrogen ion concentrations. Although nitrate concentrations did not show significant variability, a coherent gradient across the study area was observed. The large variability of calcium ion concentration across the area was related to limestone quarrying, which is prevalent in the south of the study area. Calcareous wind-blown soil may have also made a minor contribution to the abundance of calcium in the rain-water samples. It is likely, however, that a large fraction of the calcium was dry deposited to the funnels of the collectors in the form of particles. The network was not designed to study orographic enhancement of deposition, but it is suggested that this mechanism, along with wind-drift of scavenged cap-cloud droplets, cannot explain the spatial variation in ion concentrations. It is speculated that the variability in non-sea-salt sulphate concentrations may also be partially explained by reaction of CaCO 3 particles deposited to the funnels of the collectors with SO 2. Critical load exceedances in terms of deposited acidity from non-sea-salt sulphate were calculated using different spatially resolved deposition data. A better estimate of deposition in the study area was achieved by combining rainfall concentration data from the national network with the 5 km rainfall field, than the current methodology used for mapping of U.K. deposition which utilises a 20 km rainfall field. However, 20 km is considered to be the minimum resolution at which a procedure for parameterising orographic enhancement can be incorporated. Deposition and critical load exceedances in 2005 were calculated using a long-range transport model and significant improvements in the protection of soils were predicted from the projected emissions reductions.

Wet deposition of non sea-salt sulphate in the United Kingdom: The influence of natural sources

Because of its position to the west of Europe, much of the wet sulphur deposition in the west of the UK is background in the sense that it is not attributable to pollutants emitted within Europe less than four days previously. There are both natural and anthropogenic sources of this sulphur. An important natural source, especially during the summer, is dimethylsulphide (DMS) produced by marine phytoplankton. To identify the contribution of marine biogenic sulphur we have measured stable sulphur isotope ratios in precipitation. We show that biogenic sulphur is significant in summer but contributes little in winter and that around 5–10% of the annual background wet sulphur deposition is due to biogenic sources. During July and December 1993, airflow across the UK was predominantly westerly. The measured biogenic component of precipitation sulphate accounted for around 30 % of background sulphate in July but was negligible in December. Investigation of five day back-trajectories for the period indicated little opportunity for re-circulation of European emissions, suggesting that other (non-DMS) natural sources and non-European anthropogenic emissions were responsible for most of the background sulphur.

Sulphur isotope tests of seasalt correction factors in precipitation: Nova Scotia, Canada

Sulphate in precipitation is an index of atmospheric pollution but natural sources also contribute to its concentration. One of the dominant natural sources of sulphate is seasalt and reseachers have routinely calculated its proportion using reference species such as Cl−, Na+ and Mg2+. Such a method of estimation assumes conservatism of, and a purely marine origin for, the reference species. The stable isotopes of sulphur were utilized to assess the validity of these assumptions for a coastal area in Canada by taking advantage of the sulphur isotopic signature of seasalt sulphate (+20‰). The seaspray component (PSS) was calculated for 39 coastal rain events using Cl−, Na+ and Mg2+ as reference species and these parameters were plotted against the sulphur isotopic composition of sulphate in the sample. All three regression lines yielded a value of ≈ +4‰ for a sample containing no seasalt. The regression lines extrapolated to δ 34S≈+20, +17 and +16‰ using Cl−, Na+ and Mg2+ respectively for a theoretical sample whose sulphate was derived totally from seasalt. This observation confirms that for this locality, the marine component of precipitation sulphate utilizing Cl− is isotopically equivalent to sea spray sulphate, suggesting that Cl− is a suitable reference species. It also supports the use of δ 34SSO4 as a constraint on the selection of the correct reference species for estimation of the seasalt component in a particular study area.

硫黄同位体比を利用した大気降下物中硫黄の供給源寄与率の推定

新潟県の中央部に位置する長岡において,長期にわたり大気降下物の硫黄同位体比を測定した。それらの値を,大気への硫黄供給源である海塩やローカルな人為活動および石炭燃焼ガスの硫黄同位体比などと比較することにより,その季節変動などについて評価を行った。また,大気降下物に対する石炭燃焼ガスの寄与割合を試算した。その結果,冬季には大陸の石炭燃焼に由来すると考えられる硫黄が大気降下物中に平均で約20%程度含まれていると推定された。

The fractionation of sea salt and acids during transport across an Antarctic ice shelf

Analyses of Cl - , NO 3 - , SO 4 2- , Na and Mg made on a series of surface snow samples, collected at 4 km intervals along a 116 km traverse of the Fimbul Ice Shelf in Dronning Maud Land, show that fractionation of some of the sea salt species has taken place. There is depletion of Mg compared to Na in the coastal part of the traverse, but the bulk sea water ratio is maintained further inland. Evidence for Cl - fractionation is less clear, with a depletion in some sections and an enrichment in others compared to Na. Taken over the whole data-set of 120 samples, the bulk sea water ratio between the marine ions Na, Mg and Cl appears to be conservatively maintained. For all of the sea-salt components, the general trend in concentration was an increase from the ice shelf front to a maximum value approximately 45 km inland, before decreasing to a value of 10% of the maximum by the end of the traverse. Non sea-salt sulphate followed a similar trend to 45 km, but the subsequent decrease in concentration was less rapid, suggesting a greater residence time for sulphate derived from marine biogenic activity than for sea-salt aerosol. Relatively high concentrations of nitrate were found in all of the surface snow samples in comparison to samples taken from shallow pits at each end of the traverse. This may be an indication of a post depositional loss of nitrate from the snow surface. DOI: 10.1034/j.1600-0889.1993.00009.x

The ratio of MSA to non-sea-salt sulphate in Antarctic Peninsula ice cores

Methane sulphonic acid (MSA) in an ice core from Dolleman Island (70°35′S, 60°56′W) shows significantly high concentrations (typically 1-2 µm, but up to 5 µm) compared to values recorded in ice cores and in snowfall from elsewhere in Antarctica. MSA data from two other higher altitude Antarctic Peninsula ice cores, Dyer Plateau (70°31′S, 65°01′W) and Gomez Nunatak (74°01′S, 70°38′W), show that the high concentrations measured at Dolleman Island are not representative of the Peninsula region as a whole. However the mean molar MSA/nss-SO4 2- ratios at the three sites are similar (Dolleman Is, 0.46; Gomez, 0.37; Dyer, 0.32). Exceptionally high concentrations observed at Dolleman Island may be related to its proximity to the biologically productive Weddell Sea, an important source of dimethyl sulphide (DMS), the precursor of MSA. The MSA data from this site are further unusual in that in deeper sections of this core they demonstrate a well defined seasonal maximum in winter rather than in summer and are out of phase with non sea-salt sulphate, another product of the decomposition of DMS. In contrast, in a near-surface section, MSA variations are in phase with non sea-salt sulphate, with a maximum concentration in the summer layer. A change in the season of deposition of MSA from winter to summer in the recent past is not considered likely. An alternative explanation is that there has been a relocation of the MSA from summer to winter layers during burial.

Spatial and temporal variations of methanesulfonic acid and non sea salt sulfate in Antarctic ice

A simultaneous glaciochemical study of methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO4 -) has been conducted on the Antarctic plateau (South Pole, Vostok) and in more coastal regions. The objective was to investigate marine sulfur emissions in very remote areas. Firstly, our data suggest that MSA and nss-SO4 present in antarctic ice are mainly marine in origin and that DMS emissions have been significantly modulated by short term (eg. El Nino Southern Oscillation events) as well as long term climatic changes in the past. Secondly, our study of spatial variations of these two sulfur species seems to indicate that the atmosphere of coastal antarctic regions are mainly supplied by local DMS emissions whereas the atmosphere of the high plateau is also influenced by DMS emissions from more temperate marine latitudes. Thirdly, our study of the partitioning between MSA and nss-SO4 suggest that the temperature could have been an important parameter controlling the final composition of the high southern latitude atmosphere over the last climatic cycle; colder temperature favoring the formation of MSA. However, our data also support a possible role played by changes in the transport pattern of marine air to the high antarctic plateau.

The ratio of MSA to non-sea-salt sulphate in Antarctic Peninsula ice cores

Methane sulphonic acid (MSA) in an ice core from Dolleman Island (70°35′S, 60°56′W) shows significantly high concentrations (typically 1-2 µm, but up to 5 µm) compared to values recorded in ice cores and in snowfall from elsewhere in Antarctica. MSA data from two other higher altitude Antarctic Peninsula ice cores, Dyer Plateau (70°31′S, 65°01′W) and Gomez Nunatak (74°01′S, 70°38′W), show that the high concentrations measured at Dolleman Island are not representative of the Peninsula region as a whole. However the mean molar MSA/nss-SO 4 2- ratios at the three sites are similar (Dolleman Is, 0.46; Gomez, 0.37; Dyer, 0.32). Exceptionally high concentrations observed at Dolleman Island may be related to its proximity to the biologically productive Weddell Sea, an important source of dimethyl sulphide (DMS), the precursor of MSA. The MSA data from this site are further unusual in that in deeper sections of this core they demonstrate a well defined seasonal maximum in winter rather than in summer and are out of phase with non sea-salt sulphate, another product of the decomposition of DMS. In contrast, in a near-surface section, MSA variations are in phase with non sea-salt sulphate, with a maximum concentration in the summer layer. A change in the season of deposition of MSA from winter to summer in the recent past is not considered likely. An alternative explanation is that there has been a relocation of the MSA from summer to winter layers during burial. DOI: 10.1034/j.1600-0889.1992.t01-2-00007.x

Isotopic constraints on the origin of salts in Australian playas. 1. Sulphur

The δ 34S values of a variety of gypsum types from the moderm playa lakes of southern Australia show little relationship with underlying bedrock types or the δ 34S values of the bedrock sulphur. On a regional scale, in both Western Australia (Yilgarn Block) and South Australia, the δ 34S values of surficial gypmsum have a regular pattern over distances of 500 to 1000 km with highest values ( ≈ +21%‰) near coastlines decreasing to δ 34S values of ∼ 14% further inland. Sea-salt sulphate is the dominant source of sulphur to the lakes investigated, although the proportion decreases from ∼ 100% near coastlines to ∼ 55% in some inland areas. A secondary source of sulphate is also airborne, but derives from volatile biogenic sulphur compounds of largely marine origin. Sulphur derived from rock weathering is a minor component, except in areas where the bedrock contains abundant sulphur. Thus Lake Cadibarrawirracanna receives ∼ 10% of its sulphur from weathering of the pyritic Bulldog Shale (Cretaceous), and Lake Amadeus, possibly up to one-third of its sulphate from evaporites of the Bitter Springs Formation (Late Proterozoic). Our δ 34S measurements are the first tracers to directly establish the marine origin of components in Australian surface brines. The δ 34S analyses indicate the accession of sulphur from both sea-salt and marine biogenic sulphur and clearly support delivery of salts to the Australian landscape as aerosols following established wind patterns. The data negate the possibility of derivation of the lacustrine “seawater-like” brine chemistry from either marine transgression or weathering of connate salts from marine strata alone. The occurrence of non-marine evaporites exhibiting largely marine-like chemistry and isotopic signatures is probably common to low-latitude tectonically stable areas and will make the distinction between some marine and non-marine evaporites from the geological record more difficult. The regular pattern of δ 34S values of surficial sulphate in lakes and groundwaters in southern Australia provides an ideal baseline against which to search for anomalous δ 34S values associated with base-metal or gold mineralization.

Natural Sulfur Emissions into the Atmosphere

Natural atmospheric sulfur emission rates are reviewed for important components of the sulfur cycle. A summary of emission estimates is provided for vegetation, coastal and wetland ecosystems, inland soils, and oceanic environments. A brief discussion of sea salt sulfate, aeolian sources, volcanic activity, and biomass burning is also included. The emissions from plants and inland soils, may play a significant role in global sulfur cycling and very little work has been reported covering this subject. Large uncertainties continue to exist in the identity and the emission rates of the sulfur compounds and thus it is not reasonable to extrapolate these data in an attempt to balance the global sulfur cycle. Moreover interactions of enhanced anthropogenic activity with various components of the sulfur cycle need to be considered.

26-Year High Resolution Profile Of Major Anions In Snow From Coats Land, Antarctica

In January 1987, an 7.8 m core, with an age at the bottom of 26 years, was collected from a site approximately 150 km inland from Halley Station (77°02.2′S, 22°32′W; altitude 1862 m a.s.l.); 10 m temperature ≈ −30°C; accumulation rate ≈ 14 g cm−2 a−1). The site lies some 140 km from the coast of the Weddell Sea and within the area bounded in winter by the polar vortex. The core has been analysed at a frequency of ≈28 samples per accumulation year for sulphate, nitrate and chloride, and has been dated stratigraphically from the clear seasonal cycles in non sea salt sulphate (Mulvaney and Peel, 1988). With this resolution it is possible to examine the seasonal pattern of deposition of chemical species and their phase relationships. Of particular interest is the possibility that ice cores may preserve evidence for disturbances in tropospheric chemistry, associated with the recent spring-time depletion of stratospheric ozone. It has been proposed that this is accompanied by a denitrification of the stratosphere during the winter months, implying enhanced levels of NOX in the late winter/spring troposphere and in precipitation. Our data reveal a strong seasonal signal in nitrate deposition, apparently peaking in spring. Similar behaviour has been reported by Wagenbach and others (1988) for nitrate in the atmospheric aerosol, in a 3-year sequence (1983–86) from Georg von Neumayer Station (70°S, 8°W). There does not appear to be any evidence in our data of an increase in spring-time nitrate deposition since the appearance of the Antarctic ozone hole in 1978.

26-Year High Resolution Profile Of Major Anions In Snow From Coats Land, Antarctica

In January 1987, an 7.8 m core, with an age at the bottom of 26 years, was collected from a site approximately 150 km inland from Halley Station (77°02.2′S, 22°32′W; altitude 1862 m a.s.l.); 10 m temperature ≈ −30°C; accumulation rate ≈ 14 g cm−2 a−1). The site lies some 140 km from the coast of the Weddell Sea and within the area bounded in winter by the polar vortex.The core has been analysed at a frequency of ≈28 samples per accumulation year for sulphate, nitrate and chloride, and has been dated stratigraphically from the clear seasonal cycles in non sea salt sulphate (Mulvaney and Peel, 1988). With this resolution it is possible to examine the seasonal pattern of deposition of chemical species and their phase relationships.Of particular interest is the possibility that ice cores may preserve evidence for disturbances in tropospheric chemistry, associated with the recent spring-time depletion of stratospheric ozone. It has been proposed that this is accompanied by a denitrification of the stratosphere during the winter months, implying enhanced levels of NOX in the late winter/spring troposphere and in precipitation. Our data reveal a strong seasonal signal in nitrate deposition, apparently peaking in spring. Similar behaviour has been reported by Wagenbach and others (1988) for nitrate in the atmospheric aerosol, in a 3-year sequence (1983–86) from Georg von Neumayer Station (70°S, 8°W). There does not appear to be any evidence in our data of an increase in spring-time nitrate deposition since the appearance of the Antarctic ozone hole in 1978.

Ice-Core Evidence For Weddell Sea Ice Extent During The Past 200 Years

A continuous, detailed, 200-years record of the anionic species, chloride, nitrate and sulphate, has been measured on an ice core from Dolleman Island (70°35.2′ S, 60°55.5′ W), Antarctic Peninsula. The site lies on the east coast of the Peninsula, and the chemistry of the core is dominated by the changing pattern of sea-ice distribution and storm activity in the Wed dell Sea. Strong annual cycles in chloride and non sea salt sulphate reflect the dominance of the seasonal cycle in sea-ice distribution in the Weddell Sea, observed in time series derived from satellite imagery since the early 1970s. However, in the case of chloride there is also an exceptionally strong interannual variability, which in many parts of the core dominates the seasonal cycle.Secular variations in the sea-ice extent appear to have a strong influence on the climate of the region and may play a major role in determining how long-term climate change in the Antarctic Peninsula relates to global climate change. The paper examines documented evidence for sea-ice extent in the Weddell Sea sector, and evaluates the usefulness of ice-core data for reconstructing this parameter in the earlier period.

Ice-Core Evidence For Weddell Sea Ice Extent During The Past 200 Years

A continuous, detailed, 200-years record of the anionic species, chloride, nitrate and sulphate, has been measured on an ice core from Dolleman Island (70°35.2′ S, 60°55.5′ W), Antarctic Peninsula. The site lies on the east coast of the Peninsula, and the chemistry of the core is dominated by the changing pattern of sea-ice distribution and storm activity in the Wed dell Sea. Strong annual cycles in chloride and non sea salt sulphate reflect the dominance of the seasonal cycle in sea-ice distribution in the Weddell Sea, observed in time series derived from satellite imagery since the early 1970s. However, in the case of chloride there is also an exceptionally strong interannual variability, which in many parts of the core dominates the seasonal cycle. Secular variations in the sea-ice extent appear to have a strong influence on the climate of the region and may play a major role in determining how long-term climate change in the Antarctic Peninsula relates to global climate change. The paper examines documented evidence for sea-ice extent in the Weddell Sea sector, and evaluates the usefulness of ice-core data for reconstructing this parameter in the earlier period.