Janja D. Husar

Estimating historical anthropogenic global sulfur emission patterns for the period 1850-1990

Abstract It is important to establish a reliable regional emission inventory of sulfur as a function of time when assessing the possible effects of global change and acid rain. This study developed a database of annual estimates of national sulfur emissions from 1850 to 1990. A common methodology was applied across all years and countries allowing for global totals to be produced by adding estimates from all countries. The consistent approach facilitates the modification of the database and the observation of changes at national, regional, or global levels. The emission estimates were based on net production (i.e., production plus imports minus exports), sulfur content, and sulfur retention for each countrys production activities. Because the emission estimates were based on the above considerations, our database offers an opportunity to independently compare our results with those estimates based on individual country estimates. Fine temporal resolution clearly shows emission changes associated with specific historical events (e.g., wars, depressions, etc.) on a regional, national, or global basis. The spatial pattern of emissions shows that the US, the USSR, and China were the main sulfur emitters (i.e., approximately 50% of the total) in the world in 1990. The USSR and the US appear to have stabilized their sulfur emissions over the past 20 yr, and the recent increases in global sulfur emissions are linked to the rapid increases in emissions from China. Sulfur emissions have been reduced in some cases by switching from high- to low-sulfur coals. Flue gas desulfurization (FGD) has apparently made important contributions to emission reductions in only a few countries, such as Germany.

SULFUR BUDGET OF A POWER PLANT PLUME

As part of the Midwest Interstate Sulfur Transformation and Transport (MISTT) study, the summer sulfur budget of the plume of the 2400 MW coal-fired Labadie power plant near St. Louis, Missouri is assessed via aircraft data, ground monitoring network data and a two-box model. The paniculate sulfur (Sp) formation rate is obtained from three-dimensional plume mapping combined with a high time-resolution Sp sampling technique. During noon hours the SO2 conversion rate is found to be 1–4% per hour, compared to night rates below 0.5% per hour. Plume excess light scattering coefficient (bscat) and excess Sp correlated well (r = 0.87), indicating most Sp is formed in the light-scattering size range. During daytime the well-mixed plume is transported at 5ms−1 on the average; at night the July average wind speed at plume height is 12ms−1 due to the low-level jet The nocturnal plume is less than 100 m thick at 400 m above ground and is decoupled from the surface until morning. Ground monitoring data from the Regional Air Pollution Study (RAPS) show that plume entrainment into the rising mixing layer is completed by 1000 Central Daylight Time (CDT). Due to daytime vertical mixing and nocturnal decoupling, the dry removal rate for the elevated plume is highest near noon. In a daily cycle, the plume sequentially passes through a reservoir regime, dissociated from delivery to the ground and then enters the mixing-removal regime. A two-box model representing the two regimes, with diurnally periodic rate constants for transformation and removal, is employed to estimate plume sulfur budgets. Ignoring wet removal, 30–45% of the SO2 is estimated to be converted to Sp, half within the first day. Particulate sulfur is formed unevenly: the afternoon plume contributes more than its share because it rises so high that it has more time to react before removal begins. In short: transformation and removal occur mainly during the daytime, while transport is fastest at night. After a hard day of convection, reaction and deposition, the lower atmosphere relaxes at dusk while the midwestern plume takes off overnight on a jetstream and begins the next days work 300–400 km from the stack.

Continuous in situ monitoring of ambient particulate sulfur using flame photometry and thermal analysis

Abstract The sulfur component of the St. Louis ambient aerosol has been continuously monitored using a flame photometric detector (FPD) to measure particulate sulfur concentration, and in situ thermal analysis to chemically analyze the aerosol for H 2 SO 4 and its ammonium salts, NH 4 SO 4 , (NH 4 ) 3 H(SO 4 ) 2 , and (NH 4 ) 2 SO 4 . During the sixteen day monitoring period, the sulfate aerosol varied with respect to chemical composition, but tended to be in the form of the ammonium salts rather than in the form of sulfuric acid. Comparison of particulate sulfur levels with the light scattering coefficient during the monitoring period indicates that particulate sulfur was a significant constituent of the light scattering aerosol, but its mass accounted for less than half of the mass of the light scattering aerosol.

Project mistt: Kinetics of particulate sulfur formation in a power plant plume out to 300 km

Abstract As part of the 1976 field program of Project MISTT, the plume of the coal-fired Labadie power plant near St Louis was positively identified and sampled from aircraft over a range exceeding 300 km and 10 h of transport during day and night on July 9 and July 18. Measurements were made of SO 2 , NO x , ozone, particulate sulfur and various other pollutant and meteorological parameters. For both days, it is found that the gas-to-particle conversion of sulfur occurred mostly during daylight hours. The ratio of particulate to total sulfur was related linearly with the total solar radiation dose experienced by the plume. The maximum rate of paniculate sulfur formation was less than 3%h −1 on both days. Production of ozone was also observed within the plume on both occasions. Ground removal of total sulfur was found to be about 25% in the first 200 km, and its magnitude is compared to that of the gas-to-particle conversion.

General Motors Sulfate Dispersion Experiment: Summary of EPA Measurements

In October 1975, General Motors sponsored a study of sulfate exposures utilizing a fleet of catalyst equipped motor vehicles in controlled, simulated, highway driving conditions. This paper reports some EPA sponsored measurements. Sulfuric acid aerosol, in the Aitken nuclei mode, geometric mean diameter (GMD) of about 0.02 µm, is emitted in the exhaust of catalyst equipped vehicles. Measurement of sulfuric acid 20 m downwind of the roadway indicated a lack of complete neutralization by ammonia. When the wind was perpendicular to the roadway there was little coagulation of sulfuric acid into the accumulation mode, GMD of about 0.24 µm From measurement of the mass flow rate of aerosol sulfur from the simulated freeway, the aerosol sulfur emission rate per car was determined to be 3.5 ± 0.8 µg/m (5.6 ±1.3 mg/mile) corresponding to a 12 ± 3% conversion of fuel sulfur into emitted aerosol sulfur.

Intercomparison of concentration results from fine particle sulfur monitors

A one week intercomparison study was carried out to evaluate the ability of selected analytical instruments to measure fine paniculate sulfur concentrations. The instruments compared included five modified flame photometric detection systems and an automated dichotomous sampler that was coupled to an on-line, wavelength dispersive X-ray fluorescence analyzer tuned to measure sulfur on fine particle filters. All instruments were connected to a common duct. Concentrations were obtained in periods ranging from 1 to 30 min, but data were reported and intercompared on an hourly basis. Paniculate sulfur concentrations varied from 1 to 9 μg m −3. Results at all concentration levels from four of the six systems agreed to better than ± 5 % throughout the study; while all six agreed within ± 25 % of their composite-mean concentration values at the higher concentrations measured. Linear regression between the composite means and each sampler systems data set showed that the standard estimate of errors ranged from 0.2 to 0.6μgm−3, correlation coefficients from 0.979 to 0.994, and slopes ranged from 0.88 to 1.22. Sulfate concentrations were also determined every 6 h from the fine particle stage of another dichotomous sampler. They were 26 % lower than expected relative to the aerosol sulfur concentrations; thus it appears that either the aerosol sulfur was not entirely in sulfate form, or sulfate was not completely extractable by conventional procedures.

Particulate sulfur analysis: Application to high time resolution aircraft sampling in plumes

Abstract Application of vaporization flame-photometric detector (FPD) method for analysis of submicrogram amounts (> 0.3 μg) of atmospheric particulate sulfur for samples collected in plumes is described. Aerosol is deposited on a portion (0.3 cm2) of a light weight, low pressure drop glass-fiber filter with a consistent, low sulfur blank of 0.36–0.5μg cm−2. Water extracts are analyzed for sulfur with a precision of 2.5%, while the precision of the entire analytical procedure is estimated to be 5%. The aerosol sampling is performed with a sequential two-stage tape sampler which separates the ambient aerosol in coarse (>3 μm) and fine (