Atmospheric Sulfur Dioxide Research Articles

Geochemical Reservoirs and Timing of Sulfur Cycling on Mars

Sulfate-dominated sedimentary deposits are widespread on the surface of Mars, which contrasts with the rarity of carbonate deposits, and indicates surface waters with chemical features drastically different from those on Earth. While the Earth's surface chemistry and climate are intimately tied to the carbon cycle, it is the sulfur cycle that most strongly influences the Martian geosystems. The presence of sulfate minerals observed from orbit and in-situ via surface exploration within sedimentary rocks and unconsolidated regolith traces a history of post-Noachian aqueous processes mediated by sulfur. These materials likely formed in water-limited aqueous conditions compared to environments indicated by clay minerals and localized carbonates that formed in surface and subsurface settings on early Mars. Constraining the timing of sulfur delivery to the Martian exosphere, as well as volcanogenic H2O is therefore central, as it combines with volcanogenic sulfur to produce acidic fluids and ice. Here, we reassess and review the Martian geochemical reservoirs of sulfur from the innermost core, to the mantle, crust, and surficial sediments. The recognized occurrences and the mineralogical features of sedimentary sulfate deposits are synthesized and summarized. Existing models of formation of sedimentary sulfate are discussed and related to weathering processes and chemical conditions of surface waters. We also review existing models of sulfur content in the Martian mantle and analyze how volcanic activities may have transferred igneous sulfur into the exosphere and evaluate the mass transfers and speciation relationships between volcanic sulfur and sedimentary sulfates. The sedimentary clay-sulfate succession can be reconciled with a continuous volcanic eruption rate throughout the Noachian-Hesperian, but a process occurring around the mid-Noachian must have profoundly changed the composition of volcanic degassing. A hypothetical increase in the oxidation state or in water content of Martian lavas or a decrease in atmospheric pressure is necessary to account for such a change in composition of volcanic gases. This would allow the pre mid-Noachian volcanic gases to be dominated by water and carbon-species but late Noachian and Hesperian volcanic gases to be sulfur-rich and characterized by high SO2 content. Interruption of early dynamo and impact ejection of the atmosphere may have decreased the atmospheric pressure during the early Noachian whereas it remains unclear how the redox state or water content of lavas could have changed. Nevertheless, volcanic emission of SO2 rich gases since the late Noachian can explain many features of Martian sulfate-rich regolith, including the mass of sulfate and the particular chemical features (i.e. acidity) of surface waters accompanying these deposits. How SO2 impacted on Mars's climate, with possible short time scale global warming and long time scale cooling effects, remains controversial. However, the ancient wet and warm era on Mars seems incompatible with elevated atmospheric sulfur dioxide because conditions favorable to volcanic SO2 degassing were most likely not in place at this time.

Thirty years of erosion and declining atmospheric pollution at St Paul's Cathedral, London

The relationship between limestone deterioration (in the form of recession or erosion rates) and changing air quality has been the subject of much debate. A 30-year record of limestone erosion rates from the balustrade of St Paul's Cathedral, London, UK has been obtained from five micro-erosion meter (MEM) sites (last remeasured in September 2010) providing a unique, long-term dataset with which to examine the nature and causes of changing deterioration, particularly the existence of a memory effect. Whilst atmospheric sulphur dioxide concentrations fell from a daily average of 80 ppb in the early 1980s to less than 3 ppb by the late 2000s, erosion rates (measured as surface lowering or recession) only declined from 0.049 mm a−1 to 0.035 mm a−1 over the same period. A more conservative measure of the rate of surface change (which includes both lowering and raising of the surface) fell from 0.044 mm a−1 to 0.026 mm a−1 over the same period. The rates of surface change and erosion were significantly higher in the 1980–1990 measurement period compared to the 1990–2000 measurement period, whilst the average rates for the 1990–2000 measurement period were approximately the same as those for the 2000–2010 measurement period. There is no clear evidence for a memory effect, and rates of erosion and surface change now approach those found on natural karst surfaces.

Direct Measurement of SO2 in Air by Laser Induced Fluorescence Spectrometry Using a Nontunable Laser Source

Studies have been performed to evaluate a direct laser induced fluorescence (LIF) technique for measurements of atmospheric sulfur dioxide (SO2). The technique is novel in that it uses a nontunable laser source that is spectrally coincident with absorption of the SO2 molecule near 223 nm that allows sensitive measurements at environmentally relevant concentrations. In this report, the spectral characteristics and analytical capabilities of the nontunable LIF approach have been evaluated and preliminary measurements of ambient SO2 are reported. The current limit of detection is 0.5 ppb and compares well to other analytical spectroscopy methods used for atmospheric measurements of SO2. The results indicate strong feasibility for the nontunable LIF approach for SO2 measurements and suggest ways for method improvement.

Biomonitoring and spatial variability of sulphur dioxide in urban air (Portuguese)

Lichens are recognized as biological indicators of environmental pollution and also biomonitors of air quality due to their response capacity when exposed to polluted environments especially toxic gases such as sulfur dioxide (SO2) carbon dioxide (CO2) heavy metals fluorides ozone nitrogen oxides and peroxyacetyl nitrate. This work evaluated the sulfur dioxide concentration of in the air in Santa Maria city using lichen kind Usnea as biomarker. Extracts including their substrates were collected in an area without the influence of pollutants and exposed in regions of the city with intense automotive traffic. This procedure was repeated throughout four seasons of one year. After each exposure the analysis of sulfur accumulated was done using the turbidimetric technique. The Usnea sp species showed to be good for monitoring of the atmospheric sulfur dioxide. In spite of the fuels commercialized today show low pollutants concentration the increase in the number of automotive vehicles in the urban center in Santa Maria city contributes significantly to the high concentration of sulfur dioxide in the atmospheric air.

Mars cryosphere: A potential reservoir for heavy noble gases?

The two orders of magnitude drop between the measured atmospheric abundances of non-radiogenic argon, krypton and xenon in Earth versus Mars is striking. Here, in order to account for this difference, we explore the hypothesis that clathrate deposits incorporated into the current martian cryosphere have sequestered significant amounts of these noble gases assuming they were initially present in the paleoatmosphere in quantities similar to those measured on Earth (in mass of noble gas per unit mass of the planet). To do so, we use a statistical-thermodynamic model that predicts the clathrate composition formed from a carbon dioxide-dominated paleoatmosphere whose surface pressure ranges up to 3bars. The influence of the presence of atmospheric sulfur dioxide on clathrate composition is investigated and we find that it does not alter the trapping efficiencies of other minor species. Assuming nominal structural parameters for the clathrate cages, we find that a carbon dioxide equivalent pressure of 0.03 and 0.9bar is sufficient to trap masses of xenon and krypton, respectively, equivalent to those found on Earth in the clathrate deposits of the cryosphere. In this case, the amount of trapped argon is not sufficient to explain the measured Earth/Mars argon abundance ratio in the considered pressure range. In contrast, with a 2% contraction of the clathrate cages, masses of xenon, krypton and argon at least equivalent to those found on Earth can be incorporated into clathrates if one assumes the trapping of carbon dioxide at equivalent atmospheric pressures of ∼2.3bar. The proposed clathrate trapping mechanism could have then played an important role in the shaping of the current martian atmosphere.

A Simple and Simultaneous Measurement Method of Sulfur Dioxide and Nitrogen Dioxide in Atmosphere with Triethanolamine Cylindrical Filter Method

A Simple and Simultaneous Measurement Method of Sulfur Dioxide and Nitrogen Dioxide in Atmosphere with Triethanolamine Cylindrical Filter Method

Sulfur Dioxide: a Novel Gaseous Signal in the Regulation of Cardiovascular Functions

The atmospheric pollutant sulfur dioxide (SO(2)) is endogenously generated from the normal metabolism of sulfur-containing amino acids through the aspartate aminotransferase pathway. SO(2) is produced in cardiovascular tissues, and the aspartate aminotransferase mRNA is localized in endothelia and in vascular smooth muscle cells near the endothelial layer. Recent studies explored the physiological and pathophysiological effects of endogenous SO(2) on the cardiovascular system, and various potential mechanisms were found. These discoveries suggest a novel role of endogenous SO(2) in the modulation of the cardiovascular system and provide a basis for new treatments for cardiovascular diseases.

Modeling Soil Acidification in the Athabasca Oil Sands Region, Alberta, Canada

Industrial activities have proliferated across Canada's Athabasca Oil Sands Region in recent years, stimulating concerns over the impact of atmospheric sulfur dioxide (SO2) emissions on acid-sensitive terrain. Upland jack pine forests have been identified as possibly the most sensitive ecosystem in the region but despite high emissions of SO2, sulfur (S) deposition is relatively low across much of the region. The response of forest soils at 11 locations that exhibit low estimated weathering rates (< 10 mmol(c) x m(-2) x yr(-1)) was simulated for the period 1900-2100 using a dynamic hydrogeochemical model assuming no change or doubling of S deposition. The model predicted minimal impact on soil base saturation (BS), but a decline in soil solution base cation (BC) to aluminum (Al) ratio (BC:Al). The regional effects-based emissions management framework uses modeled changes in these two parameters relative to site-specific chemical thresholds to trigger actions to reduce S emissions. Modeled changes in BS are insufficient to invoke a response. Under base case conditions, modeled BC:Al reaches the chemical threshold at two and three sites within 15 and 30 years, respectively. Under conditions of double S deposition, seven sites are simulated to reach the threshold within 30 years. Nonetheless, the chemical thresholds are stringent relative to critical chemical criteria used elsewhere and the impacts of acidic deposition in the region are anticipated to be limited.

Atmospheric sulfur dioxide measurements during the 2005 and 2007 eruptions of the Piton de La Fournaise volcano: Implications for human health and environmental changes

Piton de La Fournaise is an active volcano located in the south-eastern part of Réunion Island, a tiny island found in the south-western Indian Ocean (21°S; 55,5°E). This volcano erupts regularly, at least once a year, with notable amount of degassing. Concerning the volcanic eruptions, the regulation of the French Ministry of Environment on the air quality is mainly focussed on the standards applicable for the sulfur dioxide (SO 2), in terms of public health and environmental changes. Air samples have been collected continuously every 10 days on passive diffusion tubes of SO 2, an atmospheric tracer of volcanic plumes, by ORA (Observatoire Réunionnais de l'Air), at 10 sites which have been located around the volcano since September 2005. The mean SO 2 concentrations measured over a 10-day period, in the absence of any volcanic eruption, range between very low values (1–15 μg/m 3) for all 10 sites. However, during the December 2005 eruption, notable SO 2 concentrations (factor ~ 5–25) have been measured at the locations situated on the north-west flanks of the volcano. The SO 2 degassing reached concentrations of 65–379 μg/m 3, which is mainly caused by the volcanic activity when coupled with the local-to-regional atmospheric circulations (land/sea breezes, easterlies, etc.). A wide range of atmospheric measurements was performed in the vicinity of Piton de La Fournaise in order to characterize the gaseous and particle emissions, during the April–May 2007 eruption. SO 2 concentrations were also measured continuously by SF-2000 analyser, at several coastal locations in the vicinity of the volcano, during and off eruption activities. In the absence of any volcanic eruption, the SO 2 concentrations showed day-to-day variations, with hourly-mean concentrations varying between 1 and 20 μg/m 3. These values correspond to the background concentrations for this coastal rural location and might as well come in part from non-volcanic origin. The SO 2 concentrations however were increased by a factor ~ 10–30 (with a maximum hourly-mean concentration of 2486 μg/m 3), during the April–May 2007 eruption. Hereby, several statutory thresholds were exceeded particularly at the Tremblet location. Indeed, the information and recommendation threshold (350 μg/m 3/h) as well as the alert threshold (500 μg/m 3 on 3 h consecutively) were exceeded 32 and 5 times respectively at this site. These measurements point out that during the times of eruptions with significant amounts of degassing, the threshold values for protecting the ecosystems and the air quality for human health were exceeded at several inhabited locations, with implications for human health and environmental changes, on local-to-regional scale.

Anomalous Fractionations of Sulfur Isotopes During Thermochemical Sulfate Reduction

Anomalously fractionated sulfur isotopes in many sedimentary rocks older than 2.4 billion years have been widely believed to be the products of ultraviolet photolysis of volcanic sulfur dioxide in an anoxic atmosphere. Our laboratory experiments have revealed that reduced-sulfur species produced by reactions between powders of amino acids and sulfate at 150 degrees to 200 degrees C possess anomalously fractionated sulfur isotopes: Delta33S = +0.1 to +2.1 per mil and Delta36S = -1.1 to +1.1 per mil. These results suggest that reactions between organic matter in sediments and sulfate-rich hydrothermal solutions may have produced anomalous sulfur isotope signatures in some sedimentary rocks. If so, the sulfur isotope record of sedimentary rocks may be linked to the biological and thermal evolution of Earth in ways different than previously thought.

Professor T J Chandler

Professor T J Chandler

A study of the total atmospheric sulfur dioxide load using ground-based measurements and the satellite derived Sulfur Dioxide Index

We present characteristics of the sulfur dioxide (SO 2) loading over Thessaloniki, Greece, and seven other selected sites around the world using SO 2 total column measurements from Brewer spectrophotometers together with satellite estimates of the Version 8 TOMS Sulfur Dioxide Index (SOI) over the same locations, retrieved from Nimbus 7 TOMS (1979–1993), Earth Probe TOMS (1996–2003) and OMI/Aura (2004–2006). Traditionally, the SOI has been used to quantify the SO 2 quantities emitted during great volcanic eruptions. Here, we investigate whether the SOI can give an indication of the total SO 2 load for areas and periods away from eruptive volcanic activity by studying its relative changes as a correlative measure to the SO 2 total column. We examined time series from Thessaloniki and another seven urban and non-urban stations, five in the European Union (Arosa, De Bilt, Hohenpeissenberg, Madrid, Rome) and two in India (Kodaikanal, New Delhi). Based on the Brewer data, Thessaloniki shows high SO 2 total columns for a European Union city but values are still low if compared to highly affected regions like those in India. For the time period 1983–2006 the SO 2 levels above Thessaloniki have generally decreased with a rate of 0.028 Dobson Units (DU) per annum, presumably due to the European Union's strict sulfur control policies. The seasonal variability of the SO 2 total column exhibits a double peak structure with two maxima, one during winter and the second during summer. The winter peak can be attributed to central heating while the summer peak is due to synoptic transport from sources west of the city and sources in the north of Greece. A moderate correlation was found between the seasonal levels of Brewer total SO 2 and SOI for Thessaloniki, Greece ( R = 0.710–0.763) and Madrid, Spain ( R = 0.691) which shows that under specific conditions the SOI might act as an indicator of the SO 2 total load.

Retrieval of large volcanic SO2 columns from the Aura Ozone Monitoring Instrument: Comparison and limitations

To improve global measurements of atmospheric sulfur dioxide (SO2), we have developed a new technique, called the linear fit (LF) algorithm, which uses the radiance measurements from the Ozone Monitoring Instrument (OMI) at a few discrete ultraviolet wavelengths to derive SO2, ozone, and effective reflectivity simultaneously. We have also developed a sliding median residual correction method for removing both the along‐ and cross‐track biases from the retrieval results. The achieved internal consistencies among the LF‐retrieved geophysical parameters clearly demonstrate the success of this technique. Comparison with the results from the Band Residual Difference technique has also illustrated the drastic improvements of this new technique at high SO2 loading conditions. We have constructed an error equation and derived the averaging kernel to characterize the LF retrieval and understand its limitations. Detailed error analysis has focused on the impacts of the SO2 column amounts and their vertical distributions on the retrieval results. The LF algorithm is robust and fast; therefore it is suitable for near real‐time application in aviation hazards and volcanic eruption warnings. Very large SO2 loadings (&gt;100 DU) require an off‐line iterative solution of the LF equations to reduce the retrieval errors. Both the LF and sliding median techniques are very general so that they can be applied to measurements from other backscattered ultraviolet instruments, including the series of Total Ozone Mapping Spectrometer (TOMS) missions, thereby offering the capability to update the TOMS long‐term record to maintain consistency with its OMI extension.

Morphology and elemental composition of dustfall particles inside emperor qin's terra-cotta warriors and horses museum

Indoor dustfall samples were collected in Pit 1 and Pit 2 of Emperor Qin's Terra-cotta Warriors and Horses Museum in Xi'an, Shaanxi Province, China. The morphological and elemental analysis for long-term (>10 years) and short-term (∼0.5 year) dustfall particles and lacquer pieces on the faces of partly assembled warriors were performed with scanning electron microscopy with energy dispersive X-ray spectrometer (SEM/EDX). The results showed that the majority of dustfall samples appeared to be composed of mineral dust particles, fly ash, and biological particles with different elemental compositions. Most of the mineral particles had irregular shapes with smooth edges. Small floccules of calcium sulfate were more frequently observed in long-term dustfall samples than in short-term samples, implying a progressive chemical reaction between continuous dustfall particles and atmospheric sulfur dioxide. Crystals of calcium sulfate were also found near pits on both inner and outer surfaces of lacquer pieces, revealing an acid chemical reaction between sulfur dioxide and lacquer material as the cause of the formation of erosion pits and cracks on surface of lacquer pieces.

Air separation using a catalytically modified mixed conducting ceramic hollow fibre membrane module

A membrane reactor module consisting of four gas-tight hollow fibre membranes made of the mixed ionic-electronic conducting perovskite La 0.6Sr 0.4Co 0.2Fe 0.8O 3 − δ has been tested for oxygen permeation in the temperature range of 650–1000 °C with air on one side and helium on the other. The module was operated under gradientless gas-phase conditions and in the absence of mass transfer limitations at lower temperatures. Also at lower temperature the rate-determining step for oxygen permeation was found to be oxygen reduction with the oxygen permeation performance of the module being significantly enhanced by deposition of a porous platinum catalyst film onto the air-side of the membranes. A stable but mass transfer limited flux of 0.56 μmol cm −2 s −1 (0.73 ml STP cm −2 min −1) was achieved after a period of 4 days of operation at 1000 °C and continued at this rate for a further 4 days. A non-mass transfer limited flux of ca 0.14 μmol cm −2 s −1 was obtained at 800 °C. The membrane module was operated for 500 h before the onset of significant leakage. Post operation qualitative analysis indicated localised changes in the stoichiometry of the membranes with no discernable trend, quantitative analysis on the other hand revealed that the perovskite had retained its starting composition. Post-operation analysis of the membranes revealed the presence of sulfur in the form of sulfates of strontium, cobalt and calcium and a change of surface microstructure for both the air- and lumen-side membrane surfaces. Possible sources of this sulfur contamination are: the glass-ceramic sealing material employed, the helium sweep gas and atmospheric sulfur dioxide. This contamination may contribute to the decrease in the long-term oxygen permeation rates. The metal cation stoichiometry of the perovskite showed changes in localised areas of the membranes following oxygen permeation studies.

The Effects of the Air Pollution On the Frequency of Visits Of Hypertensive Patients at the Emergency Unit in the City of Sao Paulo

P-009 Objective: the objective of this work was to analyze the association between the number of emergency medical services by hypertensive disease at an emergency unit and the concentrations of atmospheric pollutants in the city of São Paulo. Material and Methods: The studied group was of hypertensive patients (ICD 10), which in the period between February 2001 and December 2003 sought services at the emergency unit of the São Paulo hospital with hypertensive complications (elevation of blood pressure and its complications). All the analyzed patients were São Paulo residents. The atmospheric pollution data were collected from CETESB (Environmental Sanitation and Technology Co.) on a daily basis for every period of the study. Results: The data analyzed showed that the elevation on the atmospheric nitrogen dioxide (NO2), carbon monoxide (CO) and sulfur dioxide (SO2) are related to a greater number of services provided to patients who suffer form hypertension at the emergency unit of São Paulo hospital. The greatest effect on the elevation of the blood pressure was given at different moments after exposure for each pollutant previously mentioned. Thus for SO2 it has been observed an important impact until five days after the greatest atmospheric concentration. As for CO and the NO2 the same procedure occurred with seven and two days respectively. Conclusion: it has been concluded that there is an important relationship between a greater concentration of atmospheric pollutants and a greater number of emergency medical services of hypertensive patients at intensive care units.

Distribution and ecology of Lecanora conizaeoides (Lecanoraceae) in eastern Massachusetts

In its native Europe, the lichen Lecanora conizaeoides is an obligate acidophile: it always grows on substrates with a low pH. Its notorious, rapid spread through Europe in the 20th century followed an increase in atmospheric sulfur dioxide pollution that artificially acidified many substrates on which this lichen would normally never occur. During the last 50 years, this species has appeared in several scattered, coastal North American sites. In 2000, a new population was discovered in an Atlantic white cedar swamp in eastern Massachusetts; subsequently, three additional rural populations, as well as three suburban populations, have been found in the area. Specimens from these seven populations are morphologically and chemically indistinguishable from other North American and European specimens. Substrate pH measurements reveal that, with one exception, all substrates colonized by L. conizaeoides in eastern Massachusetts are highly acidic (pH < 4), thus demonstrating that this lichen is behaving as an acidophile, just as it does in Europe. At the four rural sites, L. conizaeoides displays an almost singular affinity for Atlantic white cedar (Chamaecyparis thyoides), growing on its wood and, less frequently, its bark. But at the three suburban sites, this lichen colonizes the bark of various tree species, most of which give pH values noticeably lower than at the rural sites. The acidification of these tree species at the suburban sites cannot be explained by high concentrations of atmospheric sulfur dioxide, however, because these concentrations have never approached the levels recorded in Europe during the spread of this lichen there. All our observations suggest that, in eastern Massachusetts, L. conizaeoides established itself first in rural Atlantic white cedar swamps, and is subsequently spreading to other, suburban sites which contain sufficiently acidic substrates. This pattern of invasion is strikingly similar to that hypothesized for Europe by Wirth (1985), who suggested that L. conizaeoides originated in Pinus mugo bogs, from which it gradually expanded into more urbanized areas.

Impact of sulfate nutrition on the utilization of atmospheric SO2 as sulfur source for Chinese cabbage

AbstractThe ability of Chinese cabbage (Brassica pekinensis) to utilize atmospheric sulfur dioxide (SO2) as sulfur (S) source for growth was investigated in relation to root sulfate (SO$ ^{2-}_4 $) nutrition. If seedlings of Chinese cabbage were transferred to a sulfate‐deprived nutrient solution directly after germination, plants became rapidly S‐deficient. Plant‐biomass production was decreased and the shoot‐to‐root ratio decreased. Sulfate deprivation resulted in a substantial decrease in total S, sulfate, organic‐S, and water‐soluble nonprotein thiol contents and in an increase in amino‐acid content of both shoot and root. The sulfate‐uptake rate of the root was strongly increased, whereas nitrate‐uptake rate was decreased. Upon resupply of sulfate, the onset of S‐deficiency symptoms was prevented, and growth was restored, whereas sulfate and nitrate‐uptake rates were quite similar to those of the sulfate‐sufficient plants. A 6‐day exposure to 0.12 µL L–1 SO2 of sulfate‐sufficient plants did not affect plant‐biomass production, shoot‐to‐root ratio, S and nitrogen (N) compounds of shoot and root, or sulfate and nitrate uptake by the root. Exposure of sulfate‐deprived plants to SO2 resulted in enhanced total S, organic‐S, and water‐soluble nonprotein thiol contents of the shoot. The contribution of SO2 as S source for biomass production depended on the duration of the sulfate deprivation. If Chinese cabbage was transferred to a sulfate‐deprived nutrient solution and simultaneously exposed to SO2, then plants benefited optimally from the foliarly absorbed S. The development of S‐deficiency symptoms was prevented, and shoot‐biomass production was quite similar to that of sulfate‐sufficient plants. However, upon SO2 exposure root‐biomass production was even higher than that of sulfate‐sufficient plants, whereas sulfate uptake was still enhanced. Evidently, upon SO2 exposure there was no strict and direct shoot‐to‐root signaling in tuning sulfate uptake by the root and its transport to the shoot to the need for growth, via down‐regulation of sulfate uptake and normalizing shoot–to–root biomass partitioning.

Ion chromatographic measurement of sulfide, methanethiolate, sulfite and sulfate in aqueous and air samples

Simultaneous measurement of sulfur species was investigated using ion chromatography. Sulfide, methanethiolate, sulfite and sulfate are representative of sulfur species. The aqueous sulfur species were simultaneously measured using a two-detector system: suppressor-type conductivity detector for sulfite and sulfate, and fluorometric or electrochemical detector for the reduced sulfur compounds. The major sulfur-containing gases, hydrogen sulfide, methyl mercaptan and sulfur dioxide are collected into aqueous solution as the species listed above. Collection of sulfur gases using a membrane-based cylindrical diffusion scrubber was investigated. Atmospheric hydrogen sulfide and sulfur dioxide are measured by the diffusion scrubber collection and subsequent measurement by ion chromatography without an enrichment column. In addition to the two gases, methyl mercaptan was also determined using a dual scrubber system.

Anthropogenic Sulfur Effects on Marshland Sulfate Sources

Human activity can have measurable impacts on sulfur levels in the world's water bodies. Atmospheric sulfur dioxide pollution and the resulting acid rain increases freshwater sulfate levels, and individual pollution sources deposit organic sulfur compounds in river sediments. Since the affected water bodies can be the primary sources of sulfur in adjacent marsh environments, anthropogenic pollution may influence the sulfur cycling of nearby marshes. Appropriate levels of plant-available sulfur are necessary for plant growth in marshes, though too much sulfur can damage plants. Saline marshes are often high-sulfur environments due to the steady sulfur inputs that come from seawater present in saline estuaries. Sulfur content is more variable in less saline environments, where primary inputs are rainfall and freshwater runoff. The link between human activity and sulfur levels in marsh soils has not yet been established, since research has not clearly demonstrated the effects of human activity on sulfur in saline water bodies and has generally not sought to link water-body sulfur levels to plant-available sulfur levels or area marsh health.