Dan Golomb

Carbon Capture and Storage from Fossil Fuel Use

Glossary Carbon sequestration: capture and secure storage of carbon that would otherwise be emitted to or remain in the atmosphere. Carbon sources: for this chapter, we are concerned with large stationary sources of CO2, e.g. fossil fueled power plants, cement manufacturing, ammonia production, iron and non-ferrous metal smelters, industrial boilers, refineries, natural gas wells. Carbon capture: the separation and entrapment of CO2 from large stationary sources. CO2 storage: the injection of CO2 into geologic or oceanic reservoirs for timescales of centuries or longer.

Wet sulfate and nitrate deposition patterns in eastern North America

Abstract Four year (1982–1985) averaged acid deposition (sulfate and nitrate ion) data obtained at 77 stations of the Acid Deposition System in Eastern North America (ENA) are analyzed for seasonal and spatial variations. Average sulfate concentrations over most of ENA range from 1.5–3 mgl−1. Highest sulfate depositions (>35kg ha−1y−1) occur over west Pennsylvania, the Virginias, east Michigan, and southern Ontario between Lakes Huron and Erie. Sulfate isopleths generally stretch along a SW-NE axis. In the northeast quadrant of ENA, 65–70% of the annual sulfate depositions occur in the April–September half year; some regions in southern Canada experience as much as 75% in that period. Average nitrate concentrations range from 1–2mgl−1 throughout much of ENA. Peak nitrate depositions (>20kg ha−1 y−1) fall between Lakes Michigan and Ontario; 15 kg ha−1y−1 or more cover most of the Midwest, New York, New England and south Ontario. Nitrate depositions are more evenly distributed throughout the year, with 55–65% occurring in the April-September half year. The average annual molar ratio of SO42− to NO3− varies from 0.8–1.5 over ENA. The ratio is highest at south-central receptors and lower at northern latitudes. Implications of these findings on strategies to mitigate acid deposition are discussed.

Source apportionment of wet sulfate deposition in eastern North America

Abstract An analytical model of long distance transport of air pollutants (Fay and Rosenzweig, 1980. Atmospheric Environment 14, 355–365) has been adapted for the estimation of long term (e.g. annual) wet sulfate deposition in eastern N America. The model parameters have been optimized for best agreement with 1980–1982 measurements at 109 monitoring sites in this region. The root mean square residual of the model and measurement comparison is 4 kg ha −1 y −1 ( 17% of the mean measured value). Transfer coefficients were found to decrease exponentially with source-receptor distance, having length scales between 1100 and 400 km depending upon whether the source is upwind or downwind of the receptor. Source apportionment calculated for four sites from this model shows that about half of the deposition is due to 7–8 of the largest source contributors to each site (aggregated to the state and sub-province level). A 17-year record of precipitation sulfate measured at Hubbard Brook, New Hampshire, compares favourably with the model calculation. Calculated U.S.-Canada transboundary fluxes differ from previous estimates. Isopleths of 1980–1982 yearly depositions were determined. A proposed 45 % reduction in U.S. sulfur emissions was found to produce about a 35% reduction of deposition at environmentally sensitive areas in the U.S. and Canada.

Anthropogenic nitrogen oxide transport and deposition in Eastern North America

Abstract A long-range atmospheric transport and transformation model is presented for nitrogen oxides emitted by man-made sources. The model parameters are optimized by matching the model output—annual average nitrate (NO−3) wet deposition—to observed deposition at 109 precipitation sampling stations in eastern N America that operated continuously in the years 1980–1982. The root-mean-square residual between observations and predictions is 2.9 kg NO−3 ha−1 y−1 or 19.7% of the root-mean-square observed value. The trend of estimated annual average NO−3 concentrations in precipitation at Hubbard Brook, New Hampshire compares well with the observations from 1964 to 1981. Transfer coefficients decay nearly exponentially with distance with length scales of 200–800 km, depending on source-receptor orientation with respect to the resultant annual wind direction. The model is used for source apportionment of NO−3 wet deposition at several receptors and for estimating a nitrogen budget for eastern N America, including the transboundary fluxes between the U.S. and Canada.

Seasonal, episodic and targeted control of sulfate deposition

The large differences in seasonal rates of wet sulfate deposition observed at many receptors in eastern North America imply that reducing SO2 emissions only in the summer half of the year (April-September) would bring about greater annual wet sulfate deposition reductions than reducing emissions by the same amount year-round. Targeting the emission reductions to those source areas which contribute the bulk of summer depositions in ecologically sensitive areas would increase further the gain factor, defined as the ratio of annual fractional deposition decrement to annual fractional emission decrement. In the northeastern U.S., between 10 and 15 rain episodes deposit about 60 percent of the annual wet sulfate; reducing emissions in the dry periods preceding these heavy deposition episodes could further increase the gain factor. However, it is difficult to predict these episodes, and they do not occur simultaneously over large regions of the country.

Sensitivity analysis of the kinetics of acid rain models

Abstract The great number of variables in acid rain modeling makes it difficult to pinpoint those parameters to which the model output (rain acidity) is most sensitive. The approach taken here separates the kinetic and dynamic parts, and analyzes the sensitivity of the kinetic module alone. Further simplifications and linearizations are introduced, however, the essential steps of the transformation processes are believed to be preserved. The major conclusions are: 1. (a) rain acidity is most sensitive to both the oxidation rates of SO2 to SO2−4 and NOx., to NO3−; 2. (b) dry deposition of the emitted gases, but not the formed anions, is important in determining the wet-deposited fraction; 3. (c) wet deposition is much faster than oxidation, and acidic matter is removed very rapidly from the air, but it is the oxidation rate that determines the total amount of acidity in rain and 4. (d) for similar initial concentrations of SO2 and NOx, nitrate ions may be the predominant species in wet deposition due to the faster oxidation and slower dry deposition of NOx compared to SO2.

Acid deposition-precursor emission relationship in the northeastern U.S.A.: The effectiveness of regional emission reduction

Abstract About 20% of each of the emitted SO2 and NOx are wet-deposited as sulfate and nitrate ions over the northeastern U.S.A. This leads to a mean regional precipitation acidity of 67 μmol l−1 (pH = 4.2), in good agreement with observation. Assuming a constant emission/deposition ratio, the average rain acidity can be predicted for various emission reduction scenarios.

Annual and semi-annual anthropogenic sulfur budget for Eastern North America

Abstract A balance of sulfur emissions with deposition and effluxes in eastern North America is obtained for both annual and semi-annual periods using a previously reported regional transport model. Of the total regional sulfur emissions, 60% is deposited (wet and dry) and 40% flows out of the region. U.S.A. sulfur transboundary export to Canada is eight times the reverse flow. The respective transboundary flows are apportioned among the states and provinces.

Observed and modeled trend of sulfate and nitrate in precipitation in eastern North America

Abstract The trend of annual average sulfate and nitrate ion concentrations in precipitation at 17 stations in eastern North America over 7 years 1979–1985 is estimated and compared with a modeled trend. The observed concentrations fluctuate from year-to-year about a mean value with a standard deviation of 12.7% on average. The average slope of a linear regression line at the 17 stations is −2.8% a−1 for sulfate and −0.4% a−1 for nitrate. The modeled trend at these stations, which assumes constant meteorology but a year-to-year varying emission inventory, is −2.4% a−1 for sulfate and −0.9% a−1 for nitrate.

Modeling of the 1900–1980 trend of precipitation acidity at Hubbard Brook, New Hampshire

Abstract Sulfate and nitrate concentrations in precipitation from 1900 to 1980 at Hubbard Brook, New Hampshire are modeled using constant meteorology but annually varying emission strength. The contribution of U.S. emissions to the annual average SO 2− 4 concentration increased steadily from 0.8 to 2.0 mgl −1 between 1900 and 1920 but remained fairly constant afterwards. The NO − 3 concentration increased steadily from 0.25 to 1.3mg l −1 over the eight decades. Canada emissions in 1980 added about 17% to the sulfate and 7% to the nitrate concentrations. The estimated annual average pH of precipitation decreased from 4.7 in the beginning of the century to about 4.2 at present. These calculations are in good agreement with the measurements for the period 1964–1981.