Changes In SO Research Articles

A Meteorology-Based Approach to Detecting the Relationship between Changes in SO2Emission Rates and Precipitation Concentrations of Sulfate

In this paper, the authors present an analysis of correlations between SO2 emissions and wet SO4(2-) concentrations over eastern North America that includes adjustments for the impact of meteorological variability. The approach uses multiple-regression models and readily available meteorological information to analyze precipitation chemistry data collected from 1979 to 1986 at six Utility Acid Precipitation Study Program sites. On an event-to-event basis, from 25% to 50% of the variation in concentrations, depending on site, was found to be related to meteorology. Precipitation amount, temperature, upwind emissions, and upwind mean lower-tropospheric relative humidity (indicator for upwind precipitation) were related to the natural log of SO4(2-) concentrations. Inclusion of this information resulted in a decrease in the uncertainty associated with the emission change to concentration relationship at all sites, but the results were inconsistent. Year-to-year and season-to-season changes in SO2 emissions were found to be significantly related (p less than 0.033) to variations in event and seasonal concentrations at three of the sites, but not at the other three sites. Possible explanations for this discrepancy are discussed in this paper. When all sites were examined simultaneously, strong statistical correlations (p less than 0.007) were found between emissions and concentrations, indicating that SO4(2-)more » concentrations decreased in response to seasonal and annual emission changes.« less

Response pattern of nitrifying biofilm reactor to shock loading

The effects of shock loading on the performance of a nitrifying biofilm reactor were investigated over a wide range of conditions by varying the feed concentration of ammonium (SO) and dilution rate (D) respectively. It was found that variation in the effluent ammonium concentration as SO or D changes was subject to a semi-U shaped curve. The response patterns of the nitrifying biofilm reactor to one-step change in SO at a constant dilution rate, and to one-step change in D with keeping constant SO have no significant difference.

Contemporary (1979–1988) and inferred historical status of headwater lakes in North Central Ontario, Canada

Fifty-six headwater Canadian Shield lakes were repetitively sampled from 1979 to 88 to determine their response to changes in acidic deposition of the period. Annual wet sulphate loadings varied between 38 and 83 meq m −2, with highest deposition in the late 1970s followed by somewhat lower but variable deposition in the 1980s. Median pH of the lakes increased 0·42 pH units from 1979 to 1985 and decreased by 0·15 units between 1985 and 1988. Short water renewal times ( x = 1·1 y ) promoted rapid equilibration. Since lake were so responsive to changes in SO 4 2− inputs, they were at or near steady state at all times. Comparison of predicted original pH and ANC with 1979 data indicate a median decline of 0·45 pH units and a loss of 34 μeq litre −1. ANC. Four of 9 lakes were found to be historically fishless, based on the continued presence of Chaoborus americanus in sediment cores. The remaining five lakes historically had fish populations, but fish were not collected in 1979 when pH ranged betwen 4·6 and 5·3. By 1987, fish species were found in five of these lakes where pH had increased on average by 0·9 pH units. Our data indicate that water quality improvements could allow for the reinvasion or resumption of recruitment for a significant number of Ontario lakes.

Systematic Comparison of ILWAS, MAGIC, and ETD Watershed Acidification Models: 2. Monte Carlo Analysis Under Regional Variability

A combination of input mapping (Rose et al., this issue) and Monte Carlo simulation was used to quantitatively compare the predictions of the Integrated Lake Watershed Acidification Study (ILWAS), Model of Acidification of Groundwater in Catchments (MAGIC), and Enhanced Trickle Down (ETD) watershed acidification models. Monte Carlo simulation was used to impose regional variability on selected model inputs of two dissimilar watersheds resembling those found in the northeastern United States for four different SO42− deposition scenarios. Model predictions were viewed in aggregate (distributions, medians) corresponding to population‐level predictions, and on an iteration‐by‐iteration basis corresponding to watershed‐specific predictions. For each of these, predicted values of acid‐neutralizing capacity (ANC) were treated as relative scale (changes in ANC in response to changes in deposition) and absolute scale (ANC concentrations, number of acidic lakes) predictions. Aggregate and iteration‐specific predictions viewed on a relative scale were similar for three models under small to moderate changes in SO42− deposition. Aggregate and iteration‐specific predictions differed among models when viewed on an absolute scale. Absolute scale predictions were most similar under conditions of high variability in deposition. Proper interpretation of multiple model forecasts requires objective quantification of the effects of model differences on predictions.

In situ FTIR studies on the structural mechanism of zwitter - viologen system during electrochemical charge - transfer reactions

In situ Fourier transform infrared (FTIR) spectroscopic studies during electrochemical charge transfer reactions of zwitter - viologen system are reported. In formamide electrolyte two reversible redox couples in the cyclovoltammogram are observed and could be correlated to changes in the molecular structure by studying the differential FTIR spectra. In acetonitrile electrolyte besides the assymetric behaviour in the cyclovoltammogram [1] some changes in the FTIR spectra are observed in a potential regime where no electrochemical reaction occurs. This phenomenon is related to different solubility of the molecule in these two electrolytes. Furthermore different vibrational changes of SO 3 − subunits are observed in the two electrolyte systems.

The impact of changing regional emissions on precipitation chemistry in the eastern United States

From 1975 to 1987 a 19% change in SO 2 emissions a 16% change in NO x emissions have occurred over the eastern and mid-western U.S. Six continental precipitation chemistry sites from the MAP3S network, plus the Hubbard Brook Experimental Forest, NH, show a direct relationship between emission levels and precipitation H + and SO 4 2- concentrations, except for Penn State, PA. MAP3S sites at Illinois and Ohio, located closest to the major SO 2 source regions, demonstrates statiscally significant ( P <0.05) linear regressions of SO 4 2- concentrations on SO 2 emissions. Whiteface Mt., NY, shows a weaker relationship ( P <0.01), and Hubbard Brook shows the strongest relationship ( P <0.01) between SO 2 emissions and SO 4 2- concentration in precipitation. No site shows a significant relationship ( P <0.10) for NO x emissions and NO 3 − concentrations in precipitation. Illinois, Ohio, Ithaca and Hubbard Brook show significant linear regressions of H + concentrations on emissions of SO 2 + NO x ( P <0.10, 0.05, 0.01, and 0.01, respectively). Overall, for the entire region examined, decreasing SO 2 emissions levels appear to have decreased SO 4 2- concentrations with an efficiency of 74% ± 15% (s.e.). Decreasing SO 2 plus NO x emissions (18%) have been accompanied by a decreasing H + concentrations (18%) suggesting an efficiency of conversion of 100% ± 15% (s.e.) for the study region as a whole. While significant reductions in acid species have occured at Hubbard Brook, further reductions in excess of 50% of present deposition are necessary to protect acid-sensitive ecosystems.

A wall-jet conductometric detector for determination of sulphur dioxide in air after preconcentration in water in an aerodispersion unit

Sulphur dioxide is preconcentrated from air into a polydispersed aerosol of water. The aerosol condenses on impact on the detector, on the surface of which a film of the condensate is maintained. The conductance of the liquid film is measured with a pair of platinum electrodes. The calibration dependence is nonlinear but corresponds to the theoretical model. The concentration range 0.05–2.2 mg SO 2 m −3 was studied. The detection limit was 2 × 10 −3 mg m −3; the relative standard deviation for 0.38 mg m −3 was 2.4%. A steady-state response to a change in SO 2 concentration was attained within ca. 70 s. Ammonia is the only interferent.

The hot corrosion of nickel-based ternary alloys and superalloys for gas turbine applications—I. Corrosion in SO 2/O 2 atmospheres

Hot corrosion studies of IN738 superalloy, Ni-22Cr control alloy as well as Ni-20Cr-X ternary alloys containing additions in w/w 3Al, 4Mo, 0.3Si and 5V in SO 2/O 2 equilibrated atmospheres were carried out. The investigations covered two SO 2/O 2 ratios of 2:1 and 1:4 at two temperatures of 700 and 900°C. In some cases irreproducible kinetic patterns pointed to the presence of Kirkendall voids opening between metal and scale and also to voids occurring as a result of sulphide instabilities and their subsequent conversion to oxides in the prevailing gas compositions and also to metal oxide formation in the dissociation pO 2 of NiO. The change in SO 2/O 2 ratio did not alter the corrosion rate, suggestive that the pSO 3 in the gas phase (necessary for the formation of NiSO 4) or pS 2 within the NiO layer is enough for Ni 3S 2 formation (the precursor of hot corrosion). Rates at 700°C were much greater than those at 900°C. Al, Si and V were beneficial at 700°C whereas at 900°C, V additions enhanced the corrosion rate of the control alloy due to the formation of a molten phase.

Use of PET Bottles for Wine

Two separate studies, each covering a year of testing, indicated that comparison of wine bottled in polyethylene terephthalate (PET) to that bottled in glass would depend on the size of the PET container and whether a high barrier material was used as an additional layer of protection. Wine in 3-L PET containers with a Saran layer or 4-L PET containers maintained quality for 10 to 12 months when compared to the same wine in glass containers. Changes in SO₂ and color were the most obvious measurable changes. These were due to oxygen permeation. Keeping the level of free SO₂ at <i>ca</i> 30 mg/L was effective for the preservation of the samples of white wine studied. Data are presented showing the important measurable changes over the sampling period.

Metabolic Basis for Injury to Plants from Combinations of O3 and SO2

Pisum sativum L. cv Alsweet (garden pea) and Lycopersicon esculentum Mill. flacca (mutant tomato) were chosen to evaluate the metabolic basis for plant injury from combinations of O(3) + SO(2). The plants were exposed under conditions reported to specifically alter O(3) or SO(2) toxicity; light versus dark exposures, and treatment with the fungal metabolite fusicoccin (FC), the O(3) injury inhibitor N-[2-(2-oxo-1-imidazolidiny) ethyl]-N'-phenylurea (EDU), and the SO(2) injury stimulator diethyldithiocarbamate (DDTC). Plants were grown in controlled environment chambers and exposed to combinations of O(3) (0.05-0.2 microliters per liter) and SO(2) (0.1-0.3 microliters per liter) for 2 hours. Peas treated with FC had the same or greater injury (quantified by visual rating) with O(3) + SO(2) exposures compared to plants not treated with FC. For plants with open stomata in the dark as well as light, i.e. FC-treated peas and tomatoes, there was no change or an increase in foliar necrosis with O(3) + SO(2) exposures in the dark versus light. Peas treated with EDU had an almost complete absence of O(3) injury, no change in SO(2) injury, and moderate decreases in injury from combinations of O(3) + SO(2) compared to plants not treated with EDU. Tomatoes treated with DDTC showed the same or less injury compared to plants not treated with DDTC and exposed to O(3) or SO(2). The plant responses to the experimental treatments and O(3) + SO(2) resembled O(3) responses more than SO(2) responses. The evidence for O(3)-like responses are: no change or increase in injury in the light versus dark, and EDU-induced decreases in injury. Evidences for SO(2)-like responses are: incomplete protection from injury with EDU, and no change or increased injury to FC-treated versus untreated plants. Thus, a metabolic mechanism affected by both pollutants may be associated with the combination injury, e.g. effects the plasma membrane.

Effect of Soil Processes on the Acidification of Water by Acid Deposition

AbstractThe mechanism whereby acid deposition can cause acidification of surface waters via equilibrium processes in soil solution was investigated using chemical equilibrium models. These models show that for soils with low to moderately low exchangeable bases (15% Ca2+ saturation), the soil solution pH is only slightly affected by CO2 partial pressures over the range likely to be found in soils (1–5% CO2), but the alkalinity (defined as alkalinity = 2[CO32−] + [HCO3−] + [OH−] − [H+] − [Al3+] − [Al(OH)2+] − [Al(OH)22+] of the soil solution increases rapidly with increasing CO2 partial pressure (the brackets denote molar concentrations). In contrast, solutions that are not in contact with the soil's cation exchange complex maintain alkalinity independently of CO2 partial pressure. If alkalinity is positive, the pH in such solutions rapidly increases in response to decreasing CO2 pressure. Waters having positive alkalinity will undergo a rapid rise in pH when released from the soil due to CO2 degassing, while waters with negative alkalinity (net acidity) remain acid when degassed.The effect on the soil of precipitation containing H2SO4 is to increase the SO42− concentration. In acid soils, ion exchange reactions that take place in response to increasing SO42− from 25 to 250 µmol (e−) L−1 can be expected to depress soil solution pH by 0.2 to 0.4 units. This depression is sufficient to cause a switch from positive to negative alkalinity in many soil solutions and when waters with negative alkalinity are released from the soil they remain acid when degassed. This mechanism could easily account for a change in pH of surface waters from 6.25 to 5.0 or less, while the associated change in soil solution would be &lt; 0.3 units. This mechanism does not depend on soil acidification in the sense of a reduction in base saturation. It is completely reversible and responses to changes in SO42− concentration is instantaneous, so that lags in response to changes in sulfate input levels would be controlled only by processes such as soil sulfate adsorption and biological cycling that tend to buffer changes in SO42− concentration.

The importance of soot particles and nitrous acid in oxidizing SO 2 in atmospheric aqueous droplets

Soot particles catalyze the oxidation of SO 2 H 2O, HSO 3 −, and SO 2− 3 species at the same rate; however, the rate of production of sulfate is not constant at a constant partial pressure of SO 2. The rate decreases as the pH decreases because the total concentration of S(IV) in aqueous droplets decreases as the pH decreases. The sulfate production rate has a complex dependence on the concentration of S(IV) and is not very sensitive to a change in SO 2 concentration at normal atmospheric conditions. The oxidation of SO 2 by HNO 2 in atmospheric water droplets first produces hydroxylamine disulfonate, which undergoes acid-catalyzed hydrolysis to form sulfate and hydroxylamine monosulfonate. The latter can react with HNO 2 and would then end up as nitrous oxide and sulfate Model calculations have been made comparing the relative importance of the sulfate production mechanism by soot particles and nitrous acid with other mechanisms involving liquid water. The results indicate that both soot and HNO 2 mechanisms can be very important when the lifetime of the atmospheric aqueous droplets is long.

Relationships between microbial distributions and the anaerobic decomposition of organic matter in surface sediments of long Island Sound, USA

Relative rates of the anaerobic decomposition of organic matter in the upper 10 cm of sediment from two stations in central Long Island Sound, USA, were compared. Sediment samples from discrete depth intervas were incubated anoxically and changes in SO 4 = , NH 4 + , bacterial numbers, extractable adenosine triphosphate (ATP), organic matter, and organic carbon were measured as a function of time and temperature. At both stations (∼15 and ∼34 m water-depths, respectively), the calculated rates of SO 4 = reduction and NH 4 + production decreased exponentially (approximately) with depth below the sediment-water interface. Over the same depth interval, ATP concentrations dropped by a factor of ∼6 to 7 and bacterial numbers were lower by a factor of 2 to 3. These decreases in SO 4 = reduction, NH 4 + production, bacterial numbers, and ATP, reflect a change in the physiological state of microbial populations with depth in the sediment and are consistent with the conclusions that the quantity of easily utilizable organic matter changes rapidly below the sediment surface and that food limitation controls the basic depth distribution of microbial activity. The average rates of SO 4 = reduction, ∼29 to 39 mM year-1 (22°C), in the top 10 cm are similar at both stations studied here, as well as at an additional station from a previous study. In contrast, average NH 4 + production differs by a factor of ∼2 at the two stations, reflecting differences in the C:N ratio of the organic matter supplied to the sediment surface and differences in particle reworking by macrofauna at each site. The apparent activation energy of SO 4 = reduction was 19±1 kcal mole-1 and that of NH 4 + production, 18±3 kcal mole-1. The overall quantity of carbon required to support the calculated average SO 4 = reduction rate in the top 10 cm is 23 g C m-2 year-1 and represents ∼36% of all the carbon available to the benthos annually and ∼11% of the net primary production in the water column. Directly measured fluxes of NH 4 + from sediments to overlying water at both stations agree well with those predicted from production rates obtained by the incubation techniques.

Study of the oxidation of SO 2 dissolved in 0·5 M H 2SO 4 on a gold electrode—II. A rotating disc electrode

The study of the SO 2 anodic oxidation on a gold electrode in 0·5 M H 2SO 4 has been extended using the rotating disc electrode. In addition to the phenomena observed with the stationary gold electrode, the voltametric curves obtained with the rde indicate strong inhibition of the SO 2 anodic oxidation by surface oxides. Using the theory of convective diffusion and assuming the existence of two forms of adsorbed SO 2, differing in their adsorption strengths, it has been found that the results obtained with the rde agree with the mechanism proposed in part I. Comparison of the SO 2 oxidation rate constants at a constant potential shows that the rate of SO 2 oxidation increases approximately by two or three orders of magnitude in the presence of “reduced SO 2” adsorbed on the gold surface, compared to the clean gold electrode. This increase in the SO 2 oxidation rate can be explained by changes in SO 2 adsorption in the presence of adsorbed “reduced SO 2”.

The composition of the magmatic gas of Kilauea and its behavior in the near surface environment

Kilauea gas collections are used to calculate the composition of the magmatic gas from which they were derived. Atmospheric gases by four methods results in four atomic compositions; these are used to compute four equilibrium (molecular) compositions for each sample. Simultaneous consideration of atmospheric and water contaminations defines the best method of atmospheric gas removal and shows that all variations in hydrogen content are due to contaminating water. Calculations also indicate that the carbon content of the magmatic gas is not significantly changed; large differences in sulfur are due to changes in SO ₂ . When all modifying processes are considered simultaneously, all differences in sample compositions are accounted for. The changes caused by these processes are "reversed" to return each sample to its magmatic composition; all samples yield the same composition. The original analyses are then examined for the degree to which they approach equilibrium. Although none of the analyses is an equilibrium composition, each was at equilibrium at magmatic temperatures. Imperfect quenching and oxidation after collection caused nonequilibrium. Various groups of gases have different reaction rates and exhibit a "spectrum of quenching temperatures." H ₂ O contamination and SO ₂ changes occurred before cooling; atmospheric contamination occurred after quenching. Volumetric comparisons are made to assess the magnitude of compositional changes and their overall chemical effects.

CARBONATE ALKALINITY IN THE PORE WATERS OF ANOXIC MARINE SEDIMENTS1

The principal factor affecting carbonate alkalinity in pore waters of organic‐rich aluminosilicate muds from the central Connecticut coast and a Maine fjord is bacterial sulfate reduction. Measured (titration) alkalinity is equal to that calculated from measured changes in SO42−, Mg2+, Ca2+, and NH4+. As a result of alkalinity increase, pore waters of anoxic sediments can become highly supersaturated with CaCO3. Precipitation of Ca.CO3 may not occur, however, possibly because of the inhibiting effect of dissolved organic matter. No evidence is provided by these sediments for authigenic aluminosilicate formation.