Atmospheric Environment (v.35, #11)

Atmospheric nitrogen compounds II: emissions, transport, transformation, deposition and assessment by Viney P Aneja; Paul A Roelle; George C Murray; James Southerland; Jan Willem Erisman; David Fowler; Willem A.H Asman; Naveen Patni (1903-1911).
The Atmospheric Nitrogen Compounds II: Emissions, Transport, Transformation, Deposition and Assessment workshop was held in Chapel Hill, NC from 7 to 9 June 1999. This international conference, which served as a follow-up to the workshop held in March 1997, was sponsored by: North Carolina Department of Environment and Natural Resources; North Carolina Department of Health and Human Services, North Carolina Office of the State Health Director; Mid-Atlantic Regional Air Management Association; North Carolina Water Resources Research Institute; Air and Waste Management Association, RTP Chapter; the US Environmental Protection Agency and the North Carolina State University (College of Physical and Mathematical Sciences, and North Carolina Agricultural Research Service). The workshop was structured as an open forum at which scientists, policy makers, industry representatives and others could freely share current knowledge and ideas, and included international perspectives. The workshop commenced with international perspectives from the United States, Canada, United Kingdom, the Netherlands, and Denmark. This article summarizes the findings of the workshop and articulates future research needs and ways to address nitrogen/ammonia from intensively managed animal agriculture. The need for developing sustainable solutions for managing the animal waste problem is vital for shaping the future of North Carolina. As part of that process, all aspects of environmental issues (air, water, soil) must be addressed as part of a comprehensive and long-term strategy. There is an urgent need for North Carolina policy makers to create a new, independent organization that will build consensus and mobilize resources to find technologically and economically feasible solutions to this aspect of the animal waste problem.
Keywords: Ammonia; Nitrogen compounds; Emissions; Effects; Transport; Transformation; Swine operations and abatement;

Instrument development and application in studies and monitoring of ambient ammonia by Jan Willem Erisman; Rene Otjes; Arjan Hensen; Piet Jongejan; Pim van den Bulk; Andrey Khlystov; Han Möls; Sjaak Slanina (1913-1922).
During recent years, it has become clear that ammonia is an important gas in relation to different environmental issues, such as acidification, eutrophication, human health and climate change (through particle formation). Therefore, there is a growing need to develop and apply instrumentation suitable for research into emission, dispersion, conversion and deposition of ammonia and ammonium. Recently, several instruments were developed suitable for measuring concentrations in ambient conditions even at very low levels, such as ammonia sensors suitable for monitoring and research, deposition measuring systems and aerosol samplers for on-line measurement of aerosol composition. These instruments have been tested and applied in a number of field studies. These studies include dry deposition measurements, ammonium nitrate studies in relation to the (in)direct aerosol effect, emission studies and policy evaluation with concentration and deposition monitoring data. The policy evaluation study showed that the measures to reduce ammonia emissions were not as successful as projected beforehand by statistical studies.
Keywords: Ammonia; Monitoring; Instruments; Dry deposition; Emission;

Multi-pollutant concentration measurements around a concentrated swine production facility using open-path FTIR spectrometry by J.W. Childers; E.L. Thompson; D.B. Harris; D.A. Kirchgessner; M. Clayton; D.F. Natschke; W.J. Phillips (1923-1936).
Open-path Fourier transform infrared (OP/FTIR) spectrometry was used to measure the concentrations of ammonia, methane, and other atmospheric gases around an integrated industrial swine production facility in eastern North Carolina. Several single-path measurements were made over an 8-day period from 11 to 22 January 1999. Nine different monitoring paths were configured to determine the concentration ranges of ammonia and methane throughout this facility, with an emphasis on isolating the emissions from the farrowing/nursery barns, the finishing barns, and the waste lagoon. A series of sequential measurements was made on 13 January 1999, to estimate the target gas concentrations downwind from each of these sources and at an upwind background site under similar meteorological conditions. The path-averaged concentration (mean±standard deviation) of ammonia during these measurements was below the estimated method detection limit of 0.003 ppm at the background site, 0.328±0.044 ppm between the farrowing/nursery and finishing barns, 2.063±0.140 ppm perpendicular to the airflow from the exhaust fans of the finishing barns, 0.488±0.110 ppm along the western berm of the lagoon, and 0.722±0.659 ppm along the eastern berm of the lagoon. The mean-path-averaged concentration of methane during this same time period was 1.89±0.03 ppm at the background site, 2.58±0.11 ppm between the farrowing/nursery and finishing barns, 2.70±0.05 ppm perpendicular to the airflow from the exhaust fans of the finishing barns, 2.27±0.06 ppm along the western berm of the lagoon, and 11.02±9.69 ppm along the eastern berm of the lagoon as the prevailing westerly winds died down. The concentration measurements made along different monitoring paths during this study indicate that the confinement barns can be a significant source of ammonia, while the lagoon is a major source of methane. Attempts to apply tracer-based dispersion modeling techniques to the single-path OP/FTIR data to estimate emission rates of ammonia and methane from the different sources present at this facility were met with limited success.
Keywords: Ammonia emissions; Methane emissions; Open-path Fourier transform infrared; Swine wastes;

Measuring chemical emissions using open-path Fourier transform infrared (OP-FTIR) spectroscopy and computer-assisted tomography by Lori A. Todd; Mallika Ramanathan; Kathleen Mottus; Robert Katz; Ashley Dodson; Gary Mihlan (1937-1947).
This paper reports on a field study that was part of a large-scale, multi-seasonal research study with the North Carolina Department of Environment, Health, and Natural Resources, to measure nitrogen emissions from an intensive swine confinement facility. The study measured emission rates using tracer gases and a horizontal network of open-path Fourier transform infrared (FTIR) optical rays placed less than a meter above the surface of an approximately 6 acre intensive swine waste lagoon in Eastern North Carolina. This network of rays simultaneously monitored the ammonia and the tracer gases every 2 min. The open-path measurements were combined with the mathematical mapping techniques of computer-assisted tomography (CAT) to create two-dimensional concentration maps of the gases for the entire lagoon surface. For this study, a ratioing technique was applied to the tomographic concentration maps to estimate the nitrogen emission rates (from ammonia) using known tracer emission rates. The average concentrations of ammonia measured in August, November, and May were 0.81, 0.25, and 0.74 ppm, respectively. In general, ammonia concentrations were lowest at the center of the lagoon and could vary across a lagoon from 2 to 4 times depending upon the time of the day and the meteorological conditions. Emission rates were only calculated for November and May, up until midnight. In November 1997, the average flux was 1910 μg N m−2-min−1 (range 542–4695 μg N m−2-min−1) and in May the average flux was 4775 μg N m−2-min−1 (range 2572–8499 μg N m−2-min−1). This study was important because it not only provided nitrogen emission rate measurements using a new technology which can measure concentrations over large areas in real time, it was the first large-scale outdoor field study using this application.
Keywords: Tomography; Ammonia; Swine waste;

Measurement and analysis of atmospheric ammonia emissions from anaerobic lagoons by V.P. Aneja; B. Bunton; J.T. Walker; B.P Malik (1949-1958).
Ammonia-nitrogen flux (NH3-N=(14/17)NH3) was determined from six anaerobic swine waste storage and treatment lagoons (primary, secondary, and tertiary) using the dynamic chamber system. Measurements occurred during the fall of 1998 through the early spring of 1999, and each lagoon was examined for approximately one week. Analysis of flux variation was made with respect to lagoon surface water temperature (∼15 cm below the surface), lagoon water pH, total aqueous phase NH x (=NH3+NH4 +) concentration, and total Kjeldahl nitrogen (TKN). Average lagoon temperatures (across all six lagoons) ranged from approximately 10.3 to 23.3°C. The pH ranged in value from 6.8 to 8.1. Aqueous NH x concentration ranged from 37 to 909 mg N l−1, and TKN varied from 87 to 950 mg N l−1. Fluxes were the largest at the primary lagoon in Kenansville, NC (March 1999) with an average value of 120.3 μg N m−2  min−1, and smallest at the tertiary lagoon in Rocky Mount, NC (November 1998) at 40.7 μg N m−2  min−1. Emission rates were found to be correlated with both surface lagoon water temperature and aqueous NH x concentration. The NH3-N flux may be modeled as ln(NH3-N flux)=1.0788+0.0406T L+0.0015([NH x ]) (R 2=0.74), where NH3-N flux is the ammonia flux from the lagoon surface in μg N m−2  min−1, T L is the lagoon surface water temperature in °C, and [NH x ] is the total ammonia-nitrogen concentration in mg N l−1.
Keywords: Ammonia; Ammonia emission; Swine waste lagoon; Dynamic chamber;

A detailed ammonia emission inventory for Denmark by N.J Hutchings; S.G Sommer; J.M Andersen; W.A.H Asman (1959-1968).
This paper describes the method used to create an ammonia inventory for Denmark and presents the emission factors used and their justification. The total Danish emission for 1996 was 92,700 t NH4 +–N, with agriculture accounting for nearly 99%. Emissions from animal manure accounted for 76% of agricultural emissions. We conclude that there will be a continued demand for inventories based on emission factors, despite their lack of physical and chemical realism, but that they will become more complex. This will place increased demands on the statistical information available and on the knowledge of the underlying science.
Keywords: Manure; Fertiliser; Crop; Emission map; Legislation;

Requirements for NH x models are discussed. It is very important that such models can describe the dry deposition of NH3 close to sources well. A description is given of all processes that should be included as well as references to relevant literature. For the calculation of long-term average depositions, some of these processes must be parameterized in order to keep the cpu time within reasonable bounds. Which processes should be parameterized depends on the purpose of the model calculations. A Langrangian plume model using a Gaussian plume description or a K-model with many layers can be used to model NH x deposition to nature areas embedded in agricultural areas in northern Europe (spatial resolution <5×5 km2). On the other hand long-range transport of NH x can be modelled with Lagrangian or Eulerian models with correction factors to calculate dry deposition of NH3 close to the source correctly (spatial resolution of 1-layer models >50×50 km2). TREND, a statistical atmospheric transport model was applied to calculate the concentrations and depositions of NH3 and its reaction product NH4 + aerosol to Denmark and surrounding sea areas on a 5×5 km2 grid. The model is able to reproduce measured NH3 and NH4 + aerosol concentrations reasonably well, as well as NH x wet deposition. It was found that dry deposition constitutes about 66% to the NH x total deposition to the land area of Denmark. Wet deposition, however, is relatively more important at sea and constitutes 64–67% of the NH x total deposition to the Kattegat and Southern Belt sea areas.
Keywords: Ammonia; Ammonium; Air; Precipitation; Deposition; Model; Denmark; Sea;

A methodology is presented for estimating emissions of passenger cars and light commercial vehicles complying with future European Union emission standards, which introduces appropriate reductions over the emission factors of existing vehicle technologies. For three-way catalyst gasoline vehicles, future real-world emissions are assumed to decrease by the same ratio as emission standards. Additionally, distinction is made between emissions during the thermally stabilised emission control system operation and emissions during the cold-start phase, where reductions are mainly due to the decreasing light-off time of future catalyst technologies. In case of diesel vehicles, some of the emission standards, such as 1993 CO, did not represent the actual emission level of vehicles at the time. Therefore, reductions brought over the 1993 emission factor are based both on relevant emission standards reductions and on technological considerations. In a second step, the derived emission factors are corrected to account for vehicle age and fuel quality effects. Vehicle age is introduced in the calculation via emission degradation functions of the total vehicle-accumulated mileage. The impact of improved fuels on the emissions of existing and future vehicle technologies is also modelled by applying correction factors depending on fuel specifications. A number of examples are given by applying the methodology on forecast activity data for different European countries to illustrate the expected effects of future vehicle technologies and fuels.
Keywords: Emission factor; Emission standard; Emission forecast; Passenger cars; Light commercial vehicles;

Removal of formaldehyde from indoor air by passive type air-cleaning materials by Yoshika Sekine; Atsushi Nishimura (2001-2007).
We have developed a board-like air-cleaning material consisting of activated carbon particles and manganese oxides, by which HCHO gas is decomposed into carbon dioxide even at room temperature. In this study, we investigated removal efficiencies of the air-cleaning board in a passive mode using a kinetic approach. First-order removal rate constant, k, corresponding to air change rate was characterized for the board as a function of the ratio of applied board area to space volume, S/V, and was found directly proportional to S/V with a slope of 25 at 25°C. The performance of the board was evaluated in a full-size laboratory with a constant gas generation. The board suppressed the increase of indoor HCHO concentration and the time course fitted to a theoretical curve. Then, field tests of the air-cleaning board were conducted in newly constructed multi-family houses in Japan from May 1998 to January 1999. The board not only reduced indoor HCHO concentration from 0.21 to 0.04 ppm for more than 7 months, but also enhanced the loss of HCHO gas from building materials in apartments.
Keywords: Formaldehyde; Indoor air quality; Manganese; Air exchange rate;

Urban ozone concentrations are determined by the balance between ozone destruction, chemical production and supply through advection and turbulent down-mixing from higher levels. At high latitudes, low levels of solar insolation and high horizontal advection speeds reduce the photochemical production and the spatial ozone concentration patterns are largely determined by the reaction of ozone with nitric oxide and dry deposition to the surface. A Lagrangian column model has been developed to simulate the mean (monthly and annual) three-dimensional structure in ozone and nitrogen oxides (NO x ) concentrations in the boundary-layer within and immediately around an urban areas. The short-time-scale photochemical processes of ozone and NO x , as well as emissions and deposition to the ground, are simulated. The model has a horizontal resolution of 1×1  km and high resolution in the vertical. It has been applied over a 100×100  km domain containing the city of Edinburgh (at latitude 56°N) to simulate the city-scale processes of pollutants. Results are presented, using averaged wind-flow frequencies and appropriate stability conditions, to show the extent of the depletion of ozone by city emmisions. The long-term average spatial patterns in the surface ozone and NO x concentrations over the model domain are reproduced quantitatively. The model shows the average surface ozone concentrations in the urban area to be lower than the surrounding rural areas by typically 50% and that the areas experiencing a 20% ozone depletion are generally restricted to within the urban area. The depletion of the ozone concentration to less than 50% of the rural surface values extends only 20  m vertically above the urban area. A series of monitoring sites for ozone, nitric oxide and nitrogen dioxide on a north–south transect through the city – from an urban, through a semi-rural, to a remote rural location – allows the comparison of modelled with observed data for the mean diurnal cycle of ozone concentrations. In the city centre, the cycle is well reproduced, but the ozone concentration is consistently underestimated.
Keywords: Tropospheric ozone; Lagrangian column model; Urban; Nitrogen oxides; Vertical exchange;

Ammonia volatilization from sows on grassland by S.G. Sommer; H.T. Søgaard; H.B. Møller; S. Morsing (2023-2032).
According to regulations, sows with piglets on organic farms must graze on pastures. Volatilization of ammonia (NH3) from urine patches may represent a significant source of nitrogen (N) loss from these farms. Inputs of N are low on organic farms and losses may reduce crop production. This study examined spatial variations in NH3 volatilization using a movable dynamic chamber, and the pH and total ammoniacal nitrogen (TAN) content in the topsoil of pastures with grazing sows was measured during five periods between June 1998 and May 1999. Gross NH3 volatilization from the pastures was also measured with an atmospheric mass balance technique during seven periods from September 1997 until June 1999. The dynamic chamber study showed a high variation in NH3 volatilization because of the distribution of urine; losses were between 0 and 2.8 g NH3–N m−2  day−1. Volatilization was highest near the feeding area and the huts, where the sows tended to urinate. Ammonia volatilization rate was linearly related to the product of NH3 concentration in the boundary layer and wind speed. The NH3 in the boundary layer was in equilibrium with NH3 in soil solution. Gross NH3 volatilization was in the range 0.07–2.1 kg NH3–N ha−1  day−1 from a pasture with 24 sows ha−1. Ammonia volatilization was related to the amount of feed given to the sows, incident solar radiation and air temperature during measuring periods, and also to temperature, incident solar radiation and rain 1–2 days before measurements. Annual ammonia loss was 4.8 kg NH3–N sow−1.
Keywords: Nitrogen; Emission; Grazing sows; Model;

Pollutant dispersion in urban street canopies by Jiyang Xia; Dennis Y.C. Leung (2033-2043).
The effects of building configurations on pollutant dispersion around street canopies were studied numerically. The dispersion of pollutants emitted from ground sources was simulated by continuously discharging large number of particles into the computation domain. The mean wind velocities at each time-step were firstly computed by solving the time-dependent incompressible Navier–Stokes equations, while the fluctuated velocities were determined using a statistical procedure. The trajectories of the discharged particles were obtained from a Lagrangian particle model. Three categories of numerical simulation were conducted to study the effect of different canopy geometries on the pollutant dispersion. The computed wind field data were consistent with the wind field characteristics described in the previous wind tunnel studies. A counter-clockwise vortex was found resulting in high pollutant concentration at the windward side of the downstream building of the street canopy and low pollutant concentration at the leeward side of the upstream building. The increase in height of the urban roughness buildings would facilitate the pollutant dispersion in urban street canopy under certain building configurations. Two or more vortices stacked vertically in a street canopy were found when height of the upstream and downstream buildings of a street canopy was increased, preventing pollutants from escaping out of the canopy.
Keywords: Street canyon; Lagrangian particle model; Multi-buildings; Digital tunnel; Numerical simulation;

Comparability of three spectrometers for monitoring urban aerosol by A Khlystov; G.P.A Kos; H.M ten Brink; A Mirme; Th Tuch; Ch Roth; W.G Kreyling (2045-2051).
The comparability was tested of three aerosol “spectrometers”, used in a program for monitoring the spectra of fine and ultrafine particles in three European cities. Droplets of sebacate, solid ammonium sulfate and agglomerates of elemental carbon were used in the tests, representing the major chemical and structural types of particles encountered in urban aerosol. Particles in the ultrafine range (10–100 nm) are sized by electrical mobility (SMPS, DMPS and EAS) and the “spectrometers” gave very similar size distributions for these aerosols. The integrated number concentrations were on average within 20% of the directly measured total number concentrations. Particles with a size between 0.1 and 2.5 μm, in which most of the volume/mass is concentrated, are being differently classified in the three “spectrometers”, respectively, with a low- and a high-flow LAS-X, and field charging in the EAS. The agreement between the three instruments in this size range was less good, which was partly caused by signal overload in the high-flow optical sizer, which was solved using a larger threshold. A complication occurred with the elemental carbon, which was composed of highly agglomerated entities. Particles, sized by the mobility instrumentation as being in the range of 100–400 nm, were not detected by the optical sizers. Volume (spectra) for ammonium sulfate deduced from the number spectra were compared with the mass (spectra) obtained with cascade impactors. The comparison was good for the LAS-Xs; the EAS overestimated volume/mass.
Keywords: Ultrafine aerosol; Monitoring; Optical size; Mobility;