Excess Sulfate Research Articles

Effects of long-term open-air exposure to fluoride, nitrogen compounds and SO2 on visible symptoms, pollutant accumulation and ultrastructure of Scots pine and Norway spruce seedlings

Effects of SO2, aqueous fluoride (NaF) and a solution of nitrogen compounds (NH4NO3) on the visible symptoms, pollutant accumulation and ultrastructure of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst.] seedlings were studied in an open-air experiment lasting for 3 consecutive years. Visible injury symptoms were most pronounced in combination exposures and whenever F was applied. Visible symptoms correlated well with needle pollutant concentrations. Exposure to NaF increased needle F contents particularly when F was applied with SO2 or NH4NO3. This suggests that a reduction in N or SO2 emissions, in F polluted areas, could improve the condition of conifers via decreased accumulation of phytotoxic F in the needles. Norway spruce needles accumulated 2–10 times as much S and F as those of Scots pine. Microscopic observations showed various changes in the needle mesophyll cell ultrastructure. In both species, exposure to SO2 increased significantly the amount of cytoplasmic vacuoles, suggesting detoxification of excess sulphate or low pH. F treatments resulted in a significant enlargement of plastoglobuli in Scots pine and a darkening of plastoglobuli in Norway spruce. All exposures enhanced the accumulation of lipid bodies. An increased portion of translucent plastoglobuli was most pronounced in N treatments. Many of the ultrastructural changes and visible symptoms appeared only as number of years exposed increased, indicating that long-term experiments are needed. Both visible symptoms and ultrastructural changes pointed to the more pronounced sensitivity of Norway spruce compared to Scots pine. Ultrastructural results mostly supported earlier qualitative observations of F, N and SO2 effects on needle mesophyll cell ultrastructure. However, no reduction of thylakoids in SO2 containing exposure or curling of thylakoids in F exposure could be detected in the present study.

Sulfate and mineralisable organic sulfur in pastoral soils of New Zealand. II*. A soil test for mineralisable organic sulfur

Annual pasture yield responses to sulfur, at sites where no sulfur had been added for at least 1 year, correlated well with both soil sulfate and extractable organic-S. However, sulfate was far more subject to interference from external influences, particularly fertilisers, grazing animals, and rain. A soil test is advocated in which both soil sulfate and organic-S are measured. Organic-S, extracted by phosphate (20 mM), is measured to indicate the long-term supplying power of the soil (also related to total organic-C and -S); and sulfate is measured to indicate any additions from external sources, which would have a short-term effect on pasture growth. The latter is estimated as the sulfate in excess of the quasi equilibrium value, based on the organic-S value. Potassium phosphate, in contrast to calcium phosphate, did not inhibit the extraction of organic-S (and organic matter generally) at organic-C ≥ 5%. Consequently, the organic-S extracted by potassium phosphate correlated much better with pasture response to S, and is the recommended extractant. Both potassium and calcium phosphates extracted the same amount of sulfate. The sulfate mineralised during short-term incubation, and the organic-S extracted by 0.5 M sodium bicarbonate did not correlate with S response in pasture as well as organic-S extracted by potassium phosphate. The alkaline bicarbonate extracted about 5 times more organic-S than potassium phosphate, but extracted a similar amount of sulfate.* Part I. Aust. J. Soil Res. 1996, 34, 385–403.

Compositional variations of sea‐salt‐mode aerosol particles from the North Atlantic

Individual sea‐salt‐mode aerosol particles collected during the Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange (ASTEX/MAGE) experiment in June 1992 were studied using transmission electron microscopy in both imaging and analysis modes. The set of eight samples provided an opportunity to compare “clean,” “intermediate,” and “dirty” oceanic aerosols. In the clean samples, major species include NaCl, mixed‐cation (Na, Mg, K, and Ca) sulfates, and in some particles, NaNO3. The same compounds also occur in intermediate samples, but compositional groups can be distinguished that are characterized by low‐ and high‐Cl losses from sea salt. In these samples, most Cl loss is compensated by NaNO3 formation. Several compositional groups occur in the dirty samples; these include, in addition to the particle types in clean and intermediate samples, Na2SO4 (with minor Mg, K, and Ca), (NH4)2SO4, and silicates. The uniform compositions of sea‐salt‐mode particles in the clean samples suggest that the same process was acting on all particles. Their excess sulfate and nitrate probably formed through the oxidation of SO2 in the sea‐salt aerosol water and by reactions between NOx and NaCl. On the other hand, distinct compositional groups in the dirty samples reveal that long‐range transport of continental air masses resulted in the mixing of aerosols that were exposed to different conditions. In addition to O3 oxidation, cloud processing may have contributed to the formation of excess sulfate in these samples.

Biogenic sulfur emissions and aerosols over the tropical South Atlantic: 2. One‐dimensional simulation of sulfur chemistry in the marine boundary layer

Based on experimental data collected during cruise 15/3 of R/V Meteor in the tropical South Atlantic (19°S), the marine sulfur cycle has been simulated with a one‐dimensional coupled meteorological‐chemical model. The potential of sea‐spray aerosols to act as a sink for SO2 produced from dimethylsulfide (DMS) oxidation has been examined by using a simple humidity and height dependent parameterization for sea salt aerosol distribution. Simulations show significant reduction of total SO2 concentrations to 27–82% of the values found in the absence of this heterogenous process. The sulfur species concentrations calculated using a zero‐dimensional box model agree with excess sulfate measurements in aerosol samples. The DMS, SO2, H2SO4 (sulfates formed by SO2 oxidation in the gas phase), and XSO4 (sulfates formed by SO2 oxidation in sea‐spray aerosols) vertical profiles, their diurnal cycles, and turbulent fluxes have been calculated with a one‐dimensional model, based solely on shipboard chemical measurements and meteorological radiosonde soundings. Sensitivity analysis of the sea salt aerosol parameterization shows strong dependence on the assumed aerosol distribution, thus calling for a more comprehensive approach using a coupled aerosol‐meteorological model.

Interactions among sulfate reducers, acetogens, and methanogens in anaerobic propionate systems

The complex process of propionate oxidation in anaerobic systems in the presence of excess sulfate is based on combinations of six biological reactions. Laboratory batch and continuous experiments were conducted to study which of these reactions were predominant in propionate oxidation by sulfate‐reducing bacteria in the presence of acetogens and methanogens. The engineering significance of the feed propionate to sulfate ratio was studied. In batch serum bottle experiments, sulfide was more toxic to sulfate‐reducing bacteria (SRB) than to acetogens and methanogens. Acetate was the least favored substrate for sulfate reduction. Two mechanisms appear possible under sulfate‐limited conditions: (1) propionate use by both SRB and non‐SRB acetogens and acetate and hydrogen use by methanogens and (2) propionate use by non‐SRB acetogens followed by acetate use by methanogens and hydrogen use by both SRB and methanogens. In the chemostats, at a feed propionate sulfate ratio of 2.2 (sulfate‐limited condition), the acetate formed was primarily used by methanogens. With a gradual decrease in feed propionate:sulfate ratio from 2.2 to 0.44 (sulfate‐rich condition), SRB outcompeted methanogens for acetate. In the chemostat study un‐ionized H2S concentrations of up to 178 mg S/L (total sulfide 464 mg S/L) did not inhibit sulfate reduction.

Net Uptake of Sulfate and its Transport to the Shoot in Spinach Plants Fumigated with H2S or SO2: Does Atmospheric Sulfur Affect the “Inter‐Organ” Regulation of Sulfur Nutrition?*

AbstractSpinach plants (Spinacea oleracea L. cv. Estivato) were grown on nutrient solutions under deficient, normal and excess sulfate supply. In both young and mature plants net uptake of sulfate and its transport to the shoot increased with increasing sulfate supply, but both processes proceeded at a higher rate in young as compared to mature plants. The relative sulfate transport, i.e. the relative amount of the sulfate taken up that is transported to the shoot, decreased with increasing sulfate supply. Apparently, net uptake of sulfate is not strictly controlled by the sulfur demand of the shoot, but xylem loading appears to counteract excess transport of sulfate to the shoot.Fumigation with H2S or SO2 reduced net uptake of sulfate by the roots in sulfur‐deficient plants and absolute as well as relative sulfate transport to the shoot independent of the three sulfate levels supplied to the plant. At the same time thiol contents of the shoot and the root were enhanced by fumigation with H2S and SO2. These findings are consistent with the idea that thiols produced in the leaves can mediate demand‐driven control of sulfate uptake by the roots and its transport to the shoot.

The composition of rime ice as an indicator of the quality of winter deposition

Rime ice deposition and snow chemistry has been determined over a 4-year period on the summit of Cairngorm Mountain, NE Scotland. The direction of ice deposition reflected the dominant air mass movement over the summit. Sea salt concentrations in the rime ice were approximately 2·5 times greater than in snow deposited over the same period. Excess sulphate concentrations were double, and those of nitrate nearly four times higher. The direction of deposition influenced concentrations of excess sulphate and nitrogen species (nitrate and ammonium) in rime ice. The same directional effect was found in the snow chemistry indicating increased entrapment of pollutants, or a more polluted air mass, when it prevailed from a Southerly or Easterly direction. The potential surface reactions involving gaseous species of S and N may increase the ionic loading to the rime and reflect natural ionic enrichment of the rimed snowpack surface. Because of such phenomena, rime ice is proposed as a further indicator of winter air quality revealing important information on ionic interactions and total deposition flux measurement, especially at high altitudes.

Absorption of Excess Selenium and Sulfur by Plants and Animals

High concentrations of selenium (Se) and sulfur (S) often occur in overburden soils and underlying shales associated with western coal mining areas. Knowing the role of Se and S in the soil-plant-animal system is important for proper management of mine spoil reclamation. I will discuss recent findings about Se and S forms in soil, their absorption and accumulation by plants, and their subsequent toxicity to grazing animals. Selenium absorbed by the accumulating plants is metabolized to non-protein forms, while that absorbed by the non-accumulating plants occurs predominantly as selenomethionine which is readily absorbed by animals. In animals, both acute and chronic forms of selenosis are known. Death occurs when a large dose of highly-available Se is ingested. One chronic form alkali disease, produces symptoms of inappetence, hair loss, hardening and extension of nails and hooves, reduced weight gains, and poor reproductive performance. Rosenfeld and Beath identified blind staggers as another form of selenosis, but this disorder; more appropriately called polioencephalomalacia (PEM), occurs only in ruminants. However, the attribution of blind staggers (PEM) to excess Se is being questioned. Recent experimental evidence has shown that PEM is likely caused by excess sulfur. Cases of this disorder have been documented in the U.S. and Canada when ruminants have high sulfate intake from herbage and drinking water. Decisions regarding western mine reclamation should consider the potential for not only causing excess Se, but also excess sulfate in water, soil, and plants.

Study of constancy of hydrogen-consuming flora of human colon.

The constancy of the hydrogen consuming flora of the human colon was studied in 15 healthy subjects via two measurements obtained 18 to 36 months apart. Hydrogen disappearance rate and the major products of H2-consuming bacteria, methane and sulfide, were measured during incubation of fecal homogenates with excess hydrogen and sulfate. In 11/15, the hydrogen consumption rate and the predominant hydrogen-consuming pathway (methanogenesis, sulfate reduction, or neither) remained constant. However, major shifts in these pathways were observed in four subjects, with two losing and two gaining the ability to produce methane. Methanogenesis was associated with the highest hydrogen consumption rate. This study demonstrates that clinically unrecognizable, major alterations of the colonic flora occur in healthy subjects. Understanding of the factors responsible for these alterations might allow for therapeutic manipulation of the colonic flora.

The Chemistry of Precipitation in Israel

AbstractRecent concerns about the rapid deterioration in the quality of water resources in Israel, in addition to the widely documented anthropogenic acidification of precipitation in many parts of the world, have put a “state of the art” review of our knowledge of the chemistry of precipitation in Israel on the order of the day. Electrolyte content in precipitation in Israel is inversely related to average annual precipitation, and thus is 3–6 times higher in southern than in central Israel. The major reason for these differences is the differential enrichment in components of continental origin, such as Ca2+ and HCO3−. The chemical composition of precipitation is determined by the balance between components of marine and continental origin. Na+ and Cl− are the major ions contributed by sea spray, and therefore most of the precipitation exhibits Na/Cl (molar) ratios close to that of seawater. Precipitation in the southern parts of the country is an exception. Other ions of partly marine origin are Mg2+, SO42−, K+, and, to a limited extent, Ca2+. Marine contribution to precipitation decreases with distance from the sea. The most important component of continental origin in precipitation in Israel is Ca2+, similar to precipitation in other semiarid areas surrounding the Mediterranean. Calcium in precipitation is often associated with dryfall (dust) originating in North African desert areas. NH4+ concentration levels are relatively low, and thus, the importance of this ion as an acidity‐neutralizing agent is small compared to central/northern Europe. Precipitation in Israel is neutral to mildly alkaline, with an average pH of 6.5 ± 0.8. Mildly alkaline rain is the rule in central and southern Israel. In the Golan Heights, Galilee, and the northern coastal region, most of the precipitation events are acidic. On Mt. Carmel, 40% of the rain events examined during three rainy seasons were strongly acid, and in more than 65% of the events, pH was ≤5.6. Acidity in precipitation in Israel is determined primarily by excess SO42−. Nitrates have only a subordinate role. Synoptic analysis as well as sulfur isotopic data suggest that the excess sulfate is a long‐range import from over the Mediterranean Sea, either of anthropogenic European or of biogenic/marine dimethyl sulfide (DMS) origin. In southern Israel, an isotopic amount effect was observed, whereby rain in rainier years was isotopically lighter δ18O than precipitation in the less rainy years. δ34S values of precipitation were found to be in the range of 0–15‰, thus indicating that precipitation sulfate consisted of a mixture of marine and nonmarine sulfate. Cl and Sr isotope ratios in precipitation were determined as well.

Spatial variability of the major chemistry of the Antarctic ice sheet

A compilation of reliable data for sodium, nitrate, chloride and sulphate has been made. NO3 concentrations arc remarkably consistent across Antarctica, though there appears to be some correlation with altitude and accumulation rate. Post-depositional loss of NO3 - is important at low-accumulation sites. Cl concentration (either measured directly or calculated from Na+ via the sea salt ratio) decreases with distance from the coast, though the decline is less rapid if the coastal topography is not steep or mountainous. Excess sulphate (xsSO4 2) concentration (here calculated from normal sea-salt ratios with Na+ or Cl) also declines with distance from the coast, though less quickly than Cl-. Fractionation of sea-salt ions makes the calculation of SO4 2- uncertain.

Spatial variability of the major chemistry of the Antarctic ice sheet

A compilation of reliable data for sodium, nitrate, chloride and sulphate has been made. NO3 concentrations arc remarkably consistent across Antarctica, though there appears to be some correlation with altitude and accumulation rate. Post-depositional loss of NO3- is important at low-accumulation sites. Cl concentration (either measured directly or calculated from Na+ via the sea salt ratio) decreases with distance from the coast, though the decline is less rapid if the coastal topography is not steep or mountainous. Excess sulphate (xsSO42) concentration (here calculated from normal sea-salt ratios with Na+ or Cl) also declines with distance from the coast, though less quickly than Cl-. Fractionation of sea-salt ions makes the calculation of SO42- uncertain.

Anaerobic degradation of volatile fatty acids at different sulphate concentrations

The effect of sulfate on the anaerobic breakdown of mixtures of acetate, propionate and butyrate at three different sulfate to fatty acid ratios was studied in upflow anaerobic sludge blanket reactors. Sludge characteristics were followed with time by means of sludge activity tests and by enumeration of the different physiological bacterial groups. At each sulfate concentration acetate was completely converted into methane and CO2, and acetotrophic sulfate-reducing bacteria were not detected. Hydrogenotrophic methanogenic bacteria and hydrogenotrophic sulfate-reducing bacteria were present in high numbers in the sludge of all reactors. However, a complete conversion of H2 by sulfate reducers was found in the reactor operated with excess sulfate. At higher sulfate concentrations, oxidation of propionate by sulfate-reducing bacteria became more important. Only under sulfate-limiting conditions did syntrophic propionate oxidizers out-compete propionate-degrading sulfate reducers. Remarkably, syntrophic butyrate oxidizers were well able to compete with sulfate reducers for the available butyrate, even with an excess of sulfate.

Pacific marine aerosol: 2. Equatorial gradients in chlorophyll, ammonium, and excess sulfate during SAGA 3

In February and March 1990, measurements of aerosol physicochemistry were made during five transects across the equator between 15°N and 10°S. Marked equatorial gradients in both the aerosol NH4+/SO4= ratio and the strong surface water chlorophyll were associated with boundaries separating oligotrophic waters and regions of equatorial upwelling. Highest aerosol ammonium concentrations appeared to be unrelated to continental signatures but corresponded to regions of highest chlorophyll concentrations. Favorable aerosol chemistry, wind directions, and cruise tracks in conjunction with rapid aerosol sampling made it possible to estimate the flux of ammonia from the surface in these transition regions at about 10 μmol m−2 d−1 with possibly greater values in regions where higher chlorophyll concentrations exceeded about 0.25 mg m−3. Low NH4+/SO4= values in aerosol over oligotrophic regions with chlorophyll concentrations below 0.1 mg m−3 suggest the flux in these regions was about an order of magnitude lower. Aerosol sulfate concentrations were also generally elevated over the upwelling region but showed a less pronounced relationship to chlorophyll abundance, suggesting independent source mechanisms for ammonium and sulfate. Rapid variability in mass and number concentrations were evident in convective regions. Both depletion of larger aerosol (mass) through precipitation scavenging and an increase in the number of smaller aerosol in region of subsidence indicate the complex relationship among CN, CCN, and aerosol mass in the remote marine boundary layer.

Comment on “Aqueous phase chemical processes in deliquescent sea‐salt aerosols: A mechanism that couples the atmospheric cycles of S and sea salt” by W. L. Chameides and A. W. Stelson

Comment on “Aqueous phase chemical processes in deliquescent sea‐salt aerosols: A mechanism that couples the atmospheric cycles of S and sea salt” by W. L. Chameides and A. W. Stelson

Climate of the last 500 years: High resolution ice core records

Precipitation accumulating on the Earth's ice sheets and ice caps records a variety of physical and chemical information about the atmosphere and, in some cases, provides unique insight to both the history and the mechanics of the Earth's environmental system. High resolution (well-dated) dust records from both polar ice sheets suggest a linkage between increased atmospheric dust and cooler temperatures over Antarctica, but a similar relationship is not observed in ice cores from either Greenland or China. Net accumulation histories for the last 490 years reveal no discemible global pattern although interesting regional differences and similarities exist. Excess (non-sea salt) sulfate profiles provide

Precipitation chemistry in east Central Florida from 1978 to 1987

Rainfall was collected on the University of Central Florida campus and at the Kennedy Space Center over a 10 yr period between 1978 and 1987. The chemical composition has been determined and summarized by month, annual periods and for the entire ten year record at both locations. The weighted average pH at each site was 4.58; however, annual weighted average pH was above the 10 yr average during 4 of the last 5 years. Annual nitrate concentrations increased slightly during the latter half of the record while the annual excess sulfate concentrations remained below the 10 yr weighted average during 4 of the last 5 years. Stepwise regression suggests that sulfate, nitrate, ammonium ion and Ca played major roles in the description of rainwater acidity. Annual acid deposition and annual rainfall have varied from 20 to 50 meq H+ m−2 yr−1 and 100 to 180 cm yr−1, respectively. Sea salt comprises at least 25% of the total ionic composition. Trends in acidity, excess sulfate concentration and nitrate deposition have been observed in monthly data obtained at UCF.

Hydrochemical processes at a pristine site in nord-trøndelag, mid-Norway

A detailed study of hydrochemical processes associated with vegetation and soils was undertaken at a pristine site in mid-Norway. Inputs to the site during snow-free periods showed a marked seasonality with excess sulphate concentrations in rainfall only during the summer months. However, this represented a small fraction of total annual loading and there was a dominant influence of sea salt deposition. Site vegetation modified the chemistry of water reaching the soil surface, and this also showed a marked seasonal response. The pristine nature of this site results in the soils retaining acid-soluble components which may have been eluted from impacted sites. In the soils, the extractable aluminium remains largely (70%) in the organic bound forms. The contribution of different sources of water in affecting streamwater output quality at this site are discussed.

The Quality of Fog Water Collected for Domestic and Agricultural Use in Chile

Abstract One exciting new application of meteorology is the prospect of using high-elevation fogs as an and land's water resource. This has now become reality in northern Chile where a pilot project has used 50 fog collectors to generate an average of 7200 1 of water per day during three drought years. The chemical composition of the fog water is of primary importance and is examined in this paper. A small, carefully cleaned fog-water collector was used at the site (elevation 780 m) to study the incoming fog (cloud). The ion and trace-element concentrations met Chilean and the World Health Organization's (WHO) drinking-water standards. The pH values, however, were at times extremely low. Samples from 1987 and 1988 were consistent with those from the larger dataset in 1989. The lowest observed pH was 3.46. The acidity was associated with high concentrations (89%) of excess sulfate in the 15 fog-water samples (based on Cl− as the seawater tracer element). The NO3−/SO4− equivalents ratio for the fog samples ...

Anaerobic oxidation of 1,5-pentanediol, 2-butanol, and 2-propanol by a newly isolated sulfate-reducer

Abstract A strain (strain IsBd1) of anaerobic bacterium was isolated in pure culture from a sand sample of Lake Kasumigaura using 1,4-butanediol as a sole electron-donor source, and was characterized. The bacterium was motile with a single polar flagellum and stained gram-negative. Spores were never observed. Sulfate, sulfite, thiosulfate, and elemental sulfur were reduced with concomitant growth. Even in the presence of excess sulfate, 1,4-butanediol and 1,5-pentanediol were oxidized stoichiometrically to 4-hydroxybutyrate and 5-hydroxyvalerate, respectively; 2-propanol and 2-butanol were oxidized stoichiometrically to corresponding ketones. Interspecies hydrogen transfer occurred between the isolate and Methanospirillum hungatei with ethanol, 1,3-butanediol, 1,4-butanediol, 1-butanol, 2-butanol, 2-methoxyethanol, 1,5-pentanediol, 1,3-propanediol, 1-propanol, and 2-propanol. Chemolithoheterotrophic growth was possible with formate or hydrogen and acetate in the presence of sulfate. Acetoin was fermented to acetate, 2,3-butanediol, and ethanol. Fumarate and l -malate were fermented to acetate and succinate. S-1,2-Propanediol was fermented to 1-propanol and propionate, but a racemic mixture was not fermented. When formate or hydrogen was supplied, fumarate and l -malate were reduced stoichiometrically to succinate with growth. The DNA base ratio of the isolate was 53 mol% guanine plus cytosine. Strain IsBd1 was identified as a member of the genus Desulfovibrio.