Publications Published in Chemosphere Global Change Science

1. Atmospheric nitrous oxide: patterns of global change during recent decades and centuries. Khalil, M A K; Rasmussen, R A; Shearer, M J.
   Chemosphere Global Change Science: 2002
   Notes
   Nitrous oxide is one of the major non-CO2 greenhouse gases. It is steadily increasing in the atmosphere at a rate of about 0.2% per year. Since the increasing trend is tied to agricultural processes, it is likely to continue to rise in the future and become more important in global warming. Yet very little is known about the budget of nitrous oxide. Here we present comprehensive atmospheric data that are the foundation for a better understanding of this environmentally important atmospheric constituent.
   
   
   
2. Contribution of vehicle exhaust to the global N2O budget. Becker, K H; Lorzer, J C; Kurtenbach, R; Wiesen, P; Jensen, T E; Walllington, T J.
   Chemosphere Global Change Science: 2000
   Notes
   N2O is an important greenhouse gas and accurate emission data are required to assess its impact on global climate. It is well established that automobiles, particularly those equipped with three-way catalysts, emit N2O. However, the vehicle contribution to the global N2O budget is uncertain. We report results of N2O emission measurements performed in a road tunnel in Germany and using a chassis dynamometer system in the USA. We estimate that the global vehicle fleet emits (0.12±0.06) Tg yr−1 of N2O.
   
   
   
3. Cross road and moblie tunable infrared laser measurements of nitrous oxide emissions from motor vehicles. Jimenez, J L; McManus, J B; Shorter, J H; Nelson, D D; Zahniser, M S; Koplow, M; McRae, G J; Kolb, C E.
   Chemosphere Global Change Science: 2000
   Notes
   Nitrous oxide (NO2) is a potent greenhouse gas whose atmospheric budget is poorly constrained. One known atmospheric source is the formation of N2O on three-way motor vehicle catalytic converters followed by emission with the exhaust. Previous estimates of the magnitude of this N2O source have varied widely. Two methods employing tunable infrared lasers to measure N2O/CO2 ratios from a large number of on-road motor vehicles have been developed. Both methods add support to lower estimates of N2O emissions from the US motor vehicle fleet, although significant uncertainty remains. Main Abstract: Two tunable infrared laser differential absorption spectroscopy (TILDAS) techniques have been used to measure the N2O emission levels of on-road motor vehicle exhausts. Cross road, open path laser measurements were used to assess N2O emissions from 1361 California catalyst equipped vehicles in November, 1996 yielding an emission ratio of (8.8±2.8)×10−5 N2O/CO2. A van mounted TILDAS sampling system making on-road N2O measurements in mixed traffic in June, 1998 in Manchester, New Hampshire yielded a mean N2O/CO2 ratio of (12.8±0.3)×10−5, based on correlated N2O and CO2 concentration peaks attributed to motor vehicle exhaust plumes. The correlation of N2O emissions with vehicle type, model year and NO emissions are presented for the California data set. It is found that the N2O emission distribution is highly skewed, with more than 50% of the emissions being contributed by 10% of the vehicles. Comparison of our results with those from four European tunnel studies reveals a wide range of derived N2O emission indices, with the most recent studies (including this study) finding lower values.
   
   
   
4. Effect of liquid manure on the mole fraction of nitrous oxide evolved from soil containing nitrate. Stevens, R James; Laughlin, Ronald J.
   Chemosphere Global Change Science: 2001
   Notes
   The same emission factor is applied to fertilizer N and manure N when calculating national N
   
   
   
5. Factors affecting ammonia volatilisation from a rice–wheat rotation system . Tian, G. M.; Cai, Z. C.; Cao, J. L.; Li, X. P..
   Chemosphere Global Change Science: 2001
   Notes
   Some of the major factors influencing ammonia volatilization in a rice-wheat rotation system were studied. A continuous airflow enclosure method was used to measure NH
   
   
   
6. Influence of catalyst deactivation on N20 emissions from automobiles. Odaka, Matsuo; Koike, Noriyuki; Suzuki, Hisakazu.
   Chemosphere Global Change Science: 2000
   Notes
   Though estimates of the total N2O emitted by automobiles differ widely, automobiles are believed to be a significant source of non-agricultural anthropogenic N2O emissions. At the Third Conference of the Parties (COP-3) UN Framework Convention on Climate Change, held in Kyoto in 1997, N2O was designated as a greenhouse gas whose release into the atmosphere must be reduced. This action increased the need for more accurate estimates of automotive N2O emissions. The wide variation in estimates may be attributed to differences in emission test modes, types of catalysts, and levels of catalyst deactivation involved in the tests. In this study, we examined the influence of automotive catalyst deactivation on N2O emissions from the perspective of catalyst temperature frequency distribution. Using a model gas and deactivated three-way catalysts (TWCs), we applied the exhaust emission test modes of various countries. The results indicate that the factor behind the increase of N2O emissions following catalyst deactivation is not growth in N2O generation, but a decline in the N2O decomposition capability of the catalyst. It was also found that the effect of catalyst deactivation differs according to the catalyst composition and the emission test mode.
   
   
   
7. Landfill CH4: Rates, Fates, and role in global carbon cycle. Bogner, J; Spokas, K.
   Chemosphere Global Change Science: 1993
   Notes
   Published estimates for worldwide landfill methane emissions range from 9 to 70 Tg yr−1. Field and laboratory studies suggest that maximum methane yields from landfilled refuse are about 0.06 to 0.09 m3 (dry kg)−1 refuse, depending on moisture content and other variables, such as organic loading, buffering capacity, and nutrients in landfill microenvironments. Methane yields may vary by more than an order of magnitude within a given site. Fates for landfill methane include (1) direct or delayed emission to the atmosphere through landfill cover materials or surface soils; (2) oxidation by methanotrophs in cover soils, with resulting emission of carbon dioxide; or (3) recovery of methane followed by combustion to produce carbon dioxide. The percent methane assigned to each pathway will vary among field sites and, for individual sites, through time. Nevertheless, a general framework for a landfill methane balance can be developed by consideration of landfill age, engineering and management practices, cover soil characteristics, and water balance. Direct measurements of landfill methane emissions are sparse, with rates between 10−6 and 10−8 g cm−2 s−1; very high rates of 400 kg m−2 yr−1 have been measured at a semiarid unvegetated site. The proportion of landfill carbon that is ultimately converted to methane and carbon dioxide is problematical; the literature suggests that, at best, 25% to 40% of refuse carbon can be converted to biogas carbon. Cellulose contributes the major portion of the methane potential. Routine excavation of nondecomposed cellulosic materials after one or two decades of landfill burial suggests that uniformly high conversion rates are rarely attained at field sites. For a longer-term viewpoint, considering archaeologic and geologic preservation of organic carbon through anaerobic burial, one can speculate that widespread landfilling practices in developed and developing countries may be providing a measurable sink for organic carbon, as well as increasing the atmospheric methane burden.
   
   
   
8. Methane production and theoretical consumption in UK livestock production: is a realistic balance possible?. Reay, David S.
   Chemosphere Global Change Science: 2001
   Notes
   Context abstract: Methane is an important greenhouse gas. Livestock production constitutes a large part of total UK methane emission. By comparing livestock derived methane production with three theoretical sinks, the possibility of balancing methane production with direct consumption is assessed. Ruminant livestock production contributes up to 40% of methane emission in the UK. With the increasing environmental and economic costs of greenhouse gas release, ways in which emission can be balanced with consumption must be explored. Three hypothetical sinks for ruminant livestock derived methane were examined. Only one sink appeared at all practicable in the context of modern farming. Under optimal conditions, high capacity methane oxidation in soil could conceivably reduce methane emissions where high concentrations of methane (>1%) were consistently supplied.
   
   
   
9. Nitrous oxide and dinitrogen emissions from soil under different water regimes and straw amendment. Cai, Z.; Laughlin, R. J.; Stevens, R. J..
   Chemosphere Global Change Science: 2001
   Notes
   In a laboratory study, soil amended with and without wheat straw (2.8 g kg(-1) soil) was incubated under 70% water holding capacity (WHC), continuously flooded and flooded/drained cycle conditions at 30 degrees C for 51 days. Dinitrogen and N2O evolution and ammonia volatilisation were measured during the incubation. Extractable NH4+-N and NO3--N were determined at the end of the incubation. Entrapped N-2, N2O, and dissolved NH4+-N and NO3--N in drainage water were measured in the flooded/drained cycle treatment when the floodwater was drained. The results indicated that N loss through ammonia volatilisation was undetected in all treatments due to the low soil pH value (pH(H2O) = 5.87) and no air movement. The recovery of urea-N-15 as N-2 was lowest in the continuously flooded treatments (0.75% and 0.96% with and without straw amendment, respectively), highest in the 70% WHC treatments (5.65% and 4.41%, respectively), and intermediate in the flooded/drained cycle treatments (1.79% and 2.65%, respectively). The recovery of urea-15N as N2O was in the same order as that of N2, negligible in the continuously ¯ooded treatments, 0.01% and 0.07% in the ¯ooded/drained cycle treatments, and 1.29% and 2.23% in the 70% WHC treatments, respectively. Peak N2O evolution rates were observed after the ¯oodwater was drained but no substantial evolution was found after the soil was re-flooded following drained periods. However, peak N2 evolution rates were observed after the onset of both drainage and re-flooding. Considerable quantities of N2 but no detectable N2O were entrapped in the flooded soil.
   
   
   
10. Nitrous oxide production in riparian zones and its importance to national emission invetories. Groffman, P M.
    Chemosphere Global Change Science: 2000
    Notes
    Riparian zones, which sit at the interface between terrestrial and aquatic components of the landscape, often receive and process large amounts of excess nitrogen (N) that moves out of agricultural fields towards streams. These areas thus have the potential to be "hotspots" of nitrous oxide (N2O) production in the landscape. However, current Intergovernmental Program on Climate Change (IPCC) methodologies for calculating national N2O emission inventories do not explicitly account for riparian N2O production. In this paper, we examine the nature and extent of N2O production in riparian zones, present some new data on N2O production in these areas, and propose a modification to the current IPCC methodology for quantifying N2O emissions from agriculture. We also present an example of how large-scale riparian restoration efforts to achieve agricultural water quality objectives could cause significant changes in regional N2O budgets. Although current data are inadequate to propose a quantitative emission factor for riparian N2O emissions, they suggest that these emissions are likely to be significant in many regions. Specific data on riparian N2O emissions should be collected in association with detailed watershed mass balance studies that allow for evaluation of several aspects of the IPCC methodology at once and provide constraints on the magnitude of fluxes that are difficult to measure, e.g. N2O flux, N2O:N2 ratio. Riparian and wetland restoration projects to reduce NO3− delivery to coastal waters are being considered in many areas of the world. These projects may affect regional and global N2O budgets, but only if they alter the N2O:N2 ratio during denitrification.