Sulfate mass balance

An understanding of the transformation of SO2 and NO. into other constituents no longer measurable as SOj and is needed to explain mass balance changes from one plume cross section to another. This loss of the primary pollutant SOj has been described as being exponential, and rates up to 1% per hour have been measured (30). The secondary pollutants generated by transformation are primarily sulfates and nitrates. 

The scaling tendency of the lime or limestone processes for flue gas desulfurization is highly dependent upon the supersaturation ratios of calcium sulfate and calcium sulfite, particularly calcium sulfate. The supersaturation ratios cannot be measured directly. They are determined by measuring experimentally the molalities of dissolved sulfur dioxide, sulfate, carbon dioxide, chloride, sodium and potassium, calcium, magnesium, and pH. Then by calculation, the appropriate activities are determined, and the supersaturation ratio is determined. Using the method outlined in Section IV, the concentrations of all ions and ion-pairs can be readily determined. The search variables are the molalities of bisulfite, bicarbonate, calcium, magnesium, and sulfate ions. The objective function is defined from the mass balance expressions for dissolved sulfur dioxide, sulfate, carbon dioxide, calcium, and magnesium. This equation is... 

The correlations, Equations 1-4, are used with the mass balances, Equations 5-6, to calculate the S02 partial pressure and the total dissolved concentrations of sulfite, bisulfite, calcium, S02 (sulfite plus bisulfite), and sulfate. 

Elucidation of the origin of sulfur in volcanic systems is complicated by the fact that next to SO2, significant amounts of H2S, sulfate and elemental sulfur can also be present. The bulk sulfur isotope composition must be calculated using mass balance constraints. The principal sulfur gas in equilibrium with basaltic melts at low pressure and high temperature is SO2. With decreasing temperature and/or increasing... 

The source contributions of aerosol formed from gaseous emissions, such as sulfate, nitrate and certain organic species, cannot be quantified by chemical mass balance methods, Watson (9>) proposes a unique source type which will put an upper limit on the contributions of secondary aerosol sources, but it cannot attribute those contributions to specific emitters. 

We have also looked for the presence of increased secondary organic aerosol by calculating the fine aerosol mass balance in both summer and winter during periods of high and low sulfate concentrations. Formation of secondary sulfate aerosol can cause elevated levels of sulfates and has been linked to periods of regional scale haziness in the eastern U.S. (17). 

Harada et al. studied the TiO2 photocatalytic mineralization of trimethyl phosphate, trimethyl phosphite, and O, (9-dimethyl ammonium phosphodithioate and reported excellent mass balance based on phosphate, sulfate, and carbon dioxide produced after prolonged illumination [39]. Subsequent studies found the organophosphorus insecticides dimethyl-2,2-dichlorovinyl phosphate [Eq. (5)] and di-methyl-2,2,2-trichloro-I-hydroxyethyl phosphonate were mineralized by solar irradiation in the presence of suspended TiO2 [40] ... 

After the zinc has been removed, the sulfuric acid rich solution is returned to dissolve the next batch of sludge. Over time, the sodium concentrations will read unacceptable levels in the electrolyte. A bleed stream from the zinc cells is constantly being neutralized and filtered. The saturated sodium sulfate solution thus created is crystallized out as sodium sulfate anhydrous for sale to the pulp and paper industry. Table one shows a complete mass balance for a typical batch. 

Step 3 Mass balance. Reaction 8-16 produces 1 mole of sulfate for each mole of calcium. No matter what happens to these ions, the total concentration of all species with sulfate must equal the total concentration of all species with calcium ... 

Recommended procedure From the mass balance for sulfate, find an expression for [SO]-] in terms of [Cu2+] and fH+]. Set up a spreadsheet with pH values between 2 and 12 in column A. From pH, compute [H+] and [OH ] in columns B and C. Guess a value for [Cu2+] in column D. From [HT] and [Cu2+], calculate [S04] from the equation derived from the mass balance for sulfate. From [HT], [OH, [Cu2+], and fSO ], calculate all other concentrations by using equilibrium expressions. Find the total concentration of... 

On the basis of mass balance calculations through the first 3 years of acid additions (17), only 33% of the added acid resulted in a decrease in lake alkalinity. A second 33% was neutralized by in-lake (IAG) processes, of which sulfate reduction accounted for slightly more than half and cation production for slightly less than half. Approximately 33% of the total sulfate load (wet and dry deposition, and acid additions) was lost via outflow. Therefore, about half of the added acid remained in the water column two thirds of it was unreacted and one third was neutralized by base cations. 

Mass-balance calculations for the first 3 years of acid additions indicate that the principal IAG processes are sulfate reduction and cation production. Specifically, one-third of the total sulfate input (added acid and deposition) was neutralized by in-lake processes. Increased sulfate reduction consumed slightly more than one-sixth and production of cations neutralized somewhat less than one-sixth of the acid added. Of the remaining sulfate, one-third was lost by outflow, and one-third decreased lake alkalinity. Laboratory determinations suggest that sediment-exchange processes occurring in only the top 2 cm of surficial sediments can account for the observed increase in water-column cations. Acidification of the near-surface sediments (with partial loss of exchangeable cations) will slow recovery because of the need to exchange the sediment-bound H+ and neutralize it by other processes. Reactor-based models that include the primary IAG processes predict that... 

Direct measurement of putrefaction is problematic. In laboratory microcosms in which radiolabeled (35S) algae were allowed to settle and decay on top of lake sediments, a net release of less than 5% of the to the water column was observed, and all release occurred within the first 2 weeks (38). However, ongoing microbial uptake of sulfate from the water column may have obscured further release. Maximal potential rates of cystine degradation were estimated by Jones et al. (81) to range from 0.001 to 50 xmol/L per day in Blelham Tarn sediments and by Dunnette (82) to range from 28 to 47 xmol/L per day in sediments from two lakes. Similar measurements of potential rates of hydrolysis of sulfate esters (83) tremendously overestimated the rates calculated by mass balance to occur in sediments of Wintergreen Lake (73). A better understanding of putrefaction is needed to predict retention and concentrations of S in sediments. 

Mass balance calculations clearly show that sulfate is removed from the water column by in-lake processes. Three processes are potentially important 1) diffusion of sulfate into sediments and subsequent reduction, 2) sedimentation of seston, and 3) dissimilatory sulfate reduction in the hypolimnion. 

Atmospheric Aerosol Sulfate. Isotope measurements of non-seasalt sulfate in marine aerosols (24.52.631 require that sulfate from sea spray be either physically or mathematically removed from the sample medium. Mathematically, mass balance relationships are used to correct the value for the presence of seasalt sulfate in the sample. Physical means employ impactors or cyclone separators to segregate particles based on size so that value for non-seasalt sulfate can be directly measured. 

The profile of Mg2+ in Figure 8.25 indicates downward diffusion of this constituent into the sediments. Mass balance calculations show that sufficient Mg2+ can diffuse into the sediments to account for the mass of organogenic dolomite formed in DSDP sediments (Baker and Bums, 1985 Compton and Siever, 1986). In areas of slow sedimentation rates, the diffusive flux of Mg2+ is high, and the pore waters have long residence times. Dolomites form under these conditions in the zone of sulfate reduction, are depleted in 13c, and have low trace element contents. With more rapid sedimentation rates, shallowly-buried sediments have shorter residence times, and dolomites with depleted 13C formed in the sulfate-reduction zone pass quickly into the underlying zone of methanogenesis. In this zone the DIC is enriched in 13C because of the overall reaction... 

No magnesium sulfate was added to the system for run MG-3. The objective of this run was to evaluate the system performance with decreasing Mg2+ concentration. The mass balance indicated that the total Mg2 concentration should drift down to below 500 ppm. During the run, the total Mg2+ concentration decreased from 1000 ppm to about 625 ppm toward its end. A leak was discovered at the scrubber bleed/quench recirculation pump inlet which introduced air into the process stream and therefore caused high oxidation. The high oxidation, as confirmed by solids analysis results in Table 3, was reflected by increases of the sulfate-to-sulfite ratio to above 2.5. After the air leak problem was corrected, the sulfate-to-sulfite ratio decreased, but the test average was 2.4. 

An interesting case in mineral equilibria is the presence in a soil-water system of two minerals with a common ion. An example of such a case is barium sulfate (BaS04) plus calcium sulfate (CaSO. Which mineral would be controlling SOj- in the system Two conditions would need to be met in such a system one is mass-balance while the second is charge balance. The mass-balance is given by... 

Of particular importance is the contamination of soil, because it receives pollutants from the atmosphere (e.g., sulfates and nitrates resulting from oxidation of nitrogen and sulfur oxides, and metals from smelters) and from the hydrosphere (e.g., sediments that concentrate heavy metals from aqueous bodies and mining operations). In multimedia mass-balance models, soil is an important sink as well as a conduit for mass transfer to vegetation and shallow groundwater. 

The computerized aqueous chemical model of Truesdell and Jones (, 3), WATEQ, has been greatly revised and expanded to include consideration of ion association and solubility equilibria for several trace metals, Ag, As, Cd, Cu, Mn, Ni, Pb and Zn, solubility equilibria for various metastable and(or) sparingly soluble equilibrium solids, calculation of propagated standard deviation, calculation of redox potential from various couples, polysulfides, and a mass balance section for sulfide solutes. Revisions include expansion and revision of the redox, sulfate, iron, boron, and fluoride solute sections, changes in the possible operations with Fe (II, III, and II + HI), and updating the model s thermodynamic data base using critically evaluated values (81, 50, 58) and new compilations (51, 26 R. M. Siebert and... 

Dissolution of feldspars is a logical source of dissolved silica, calcium, sodium, and potassium in groundwater. Similarly, the reaction of carbon dioxide-charged water with silicate minerals is a logical source of bicarbonate. Rogers (1987) examined these and other hypotheses using a mass-balance approach. In these calculations, chloride and sulfate were not considered, and the beginning concentrations were considered to be... 

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