Total Direct Emissions Research Articles

Fertilizer-induced emission factors and background emissions of N2O from vegetable fields in China

The estimation of nitrous oxide (N2O) emissions based on specific cropping systems is important for accurate national N2O budgets. Intensively managed vegetable cultivation is responsible for large N2O emissions in mainland China. However, little information can be obtained on the nationwide estimation of direct N2O emissions from vegetable fields. Estimates of fertilizer-induced direct N2O emissions from vegetable fields in mainland China were thus obtained by compiling and analyzing reported data in peerreviewed journals and research reports. The results indicated that the seasonal N2O emissions from vegetable fields significantly increased with nitrogen (N) fertilizer application (p 100 and � 200 d. Comparable results were obtained by the maximum likelihood (ML) model, with an EF of 0.49 � 0.06% and background N2O emissions of 1.228 � 0.189 kg N ha � 1 yr �1 . Based on the OLS-derived parameters, the fertilizer-induced direct emissions and background emissions of N2O were estimated to be 66.95 Gg N and 19.63 Gg N, respectively, in 2009, and the annual N2O emissions were much higher in the provinces of Shandong, Henan, Hebei and Sichuan. The estimated N2O emissions from vegetable fields accounted for 21.4% of the total direct N2O emissions from Chinese croplands, with large uncertainties. Therefore, the EF and background emissions of N2O for each cropping system, particularly for intensively managed vegetable fields, should be specifically determined for accurate national N2O inventories. 2011 Published by Elsevier Ltd.

Greenhouse gas emissions in China 2007: Inventory and input–output analysis

For greenhouse gas (GHG) emissions by the Chinese economy in 2007 with the most recent statistics availability, a concrete inventory covering CO 2, CH 4, and N 2O is composed and associated with an input–output analysis to reveal the emission embodiment in final consumption and international trade. The estimated total direct GHG emission amounts to 7456.12 Mt CO 2-eq by the commonly referred IPCC global warming potentials, with 63.39% from energy-related CO 2, 22.31% from non-energy-related CO 2, 11.15% from CH 4 and 3.15% from N 2O. Responsible for 81.32% of the total GHG emissions are the five sectors of the Electric Power/Steam and Hot Water Production and Supply, Smelting and Pressing of Ferrous and Nonferrous Metals, Nonmetal Mineral Products, Agriculture, and Coal Mining and Dressing, with distinctive emission structures. The sector of Construction holds the top GHG emissions embodied in both domestic production and consumption, and the emission embodied in gross capital formation is prominently more than those in other components of the final consumption characterized by extensive investment in contrast to limited household consumption. China is a net exporter of embodied GHG emissions, with emissions embodied in exports of 3060.18 Mt CO 2-eq, in magnitude up to 41.04% of the total direct emission.

Methane emissions by Chinese economy: Inventory and embodiment analysis

Concrete inventories for methane emissions and associated embodied emissions in production, consumption, and international trade are presented in this paper for the mainland Chinese economy in 2007 with most recent availability of relevant environmental resources statistics and the input–output table. The total CH 4 emission by Chinese economy 2007 estimated as 39,592.70 Gg is equivalent to three quarters of China's CO 2 emission from fuel combustion by the global thermodynamic potentials, and even by the commonly referred lower IPCC global warming potentials is equivalent to one sixth of China's CO 2 emission from fuel combustion and greater than the CO 2 emissions from fuel combustion of many economically developed countries such as UK, Canada, and Germany. Agricultural activities and coal mining are the dominant direct emission sources, and the sector of Construction holds the top embodied emissions in both production and consumption. The emission embodied in gross capital formation is more than those in other components of final demand characterized by extensive investment and limited consumption. China is a net exporter of embodied CH 4 emissions with the emission embodied in exports of 14,021.80 Gg, in magnitude up to 35.42% of the total direct emission. China's exports of textile products, industrial raw materials, and primary machinery and equipment products have a significant impact on its net embodied emissions of international trade balance. Corresponding policy measures such as agricultural carbon-reduction strategies, coalbed methane recovery, export-oriented and low value added industry adjustment, and low carbon energy polices to methane emission mitigation are addressed.

Nitrous oxide (N 2O) in the Seine river and basin: Observations and budgets

In the Seine basin (71 730 km 2) intensive use of N fertilizers in agriculture and the release of reduced N in urban wastewater, not fully eliminated in treatment plants, have deeply perturbed the regional nitrogen cycle, namely by promoting intense nitrification and denitrification, two key microbial processes involved in N 2O emission. Sampling surveys in the whole Seine drainage network have shown that N 2O water concentrations are always far above saturation with respect to atmospheric concentrations. Highest values are found in 1st order streams (1–4 μg N l −1), decrease by out-gazing down to 4th order rivers (0.5 μg N l −1) and increase again in polluted higher order rivers (4 μg N l −1). Calculated values of gas transfer velocities and the observed N 2O supersaturation by stream order was used to estimate N 2O emissions for the whole water surface area of the Seine drainage network to 100–200 × 10 3 kg N-N 2O yr −1. The results show that a major fraction of the emission occurs in head-water streams. On the basis of previous work, the emission by wastewater treatment plants – WWTPs – has been estimated at the scale of the Seine basin, to 150–260 × 10 3 kg N-N 2O yr −1, i.e. to be in the same range as N 2O emissions from the entire water surface. Using an emission factor approach, based on an intensive literature survey considering grassland, cropland and forest soils distribution, the total direct emissions of N 2O of the Seine basin was estimated to 10 400 × 10 3 kg N-N 2O yr −1 among which 2500 × 10 3 kg N-N 2O yr −1 are issued from the forested soils and 7900 × 10 3 kg N-N 2O yr −1 from agricultural land. The latter figure agrees well with the [Intergovernmental Panel on Climate Change (IPCC), 2006. AFOLU, N 2O Emissions from Managed Soils, and CO 2 Emissions from Lime and Urea Application, vol. 4, 54 pp (Chapter 11)] estimate of 8250 × 10 3 kg N-N 2O yr −1. The quantified indirect emissions (from the river-atmosphere interface and from the WWTPs) thus represent 3–6% of the direct agricultural emissions of the Seine basin. However, N 2O indirect emissions from ‘riparian zones’ have only been roughly calculated and, thus, are remaining uncertain. A conservative estimate might increase the indirect emissions to about 13–17% of the direct ones.

Quantification of greenhouse gas emissions from a beef feedlot system in south-east Australia during summer conditions

Feedlot management systems for beef cattle are becoming a more common practice in Australia reflecting opportunities to ensure quality of product whilst maintaining cost efficiencies within production. However, feedlot systems have been identified as point sources of greenhouse gases emissions (GGE: methane, nitrous oxide and the indirect greenhouse gas ammonia). It has been estimated that feedlot systems contribute 3.5% of total direct methane emissions (Alford et al. 2006), and 30% of total emissions from livestock wastes. Furthermore, approximately 1% of total N2O emissions from agriculture are attributed to livestock. This paper reports methane, N2O and NH3 emissions from an Australian feedlot system managed under summer climatic conditions. It compares actual measured emissions with estimated from three recognised models used by national governments to estimate total GGE per annum from livestock agriculture.

Estimation of N2O emissions from agricultural soils in Canada. II. 1990–2005 inventory

International initiatives such as the United Nations Framework Convention on Climate Change and the Kyoto Protocol require that countries conduct national inventories of their greenhouse gas emissions. The primary objective of the present study was to apply a country-specific (Tier II) methodology at the regional (≈150 000 ha) scale to estimate direct N2O emissions from agricultural soils in Canada for the period 1990–2005. Other N2O sources such as manure management and indirect emissions were estimated using the Tier I Intergovernmental Panel on Climate Change (IPCC) methodology and were included to provide a complete assessment of agricultural N2O emissions. Total N2O emissions from agricultural sources averaged 58.1 Gg N2O-N yr-1 between 1990 and 2005 (from 48.9 in 1990 to 71.6 Gg N2O-N yr-1 in 2004). Of these mean emissions, 39.3 Gg N2O-N yr-1 or 68% were direct emissions from soils, 8.7 Gg N2O-N yr-1 or 15% were direct emissions from animal waste management systems and 10.1 Gg N2O-N yr-1 or 17% were from indirect emissions. Application of synthetic N fertilizers was the largest direct source of soil N2O with average emissions during the inventory period of 13.7 Gg N2O-N yr-1 or 35% of direct emissions. Crop residues (9.3 Gg N2O-N yr-1; 24%), grazing animals (6.8 Gg N2O-N yr-1; 17%) and manure applied to soils (4.1 Gg N2O-N yr-1; 10%) were the other major direct soil N2O sources. New non-IPCC N2O sources/offsets included in the Tier II methodology accounted for 10% of total direct soil emissions. Emissions occurring during summerfallow (2.2 Gg N2O-N yr-1; 6%), in lower portions of the landscape (2.2 Gg N2O-N yr-1; 6%), and following irrigation (0.7 Gg N2O-N yr-1; 2%) were partially offset by changes in tillage practices (-1.2 Gg N2O-N yr-1; -3%) and in coarse-textured soils (-0.2 Gg N2O-N yr-1; -1%). Differences in N2O estimates between Tier I and Tier II approaches mainly arise from the use of lower fertilizer-induced emission factors in the dry Prairie region and the addition of several new N2O sources/offsets in the Tier II methodology. Key words: Nitrous oxide, soils, greenhouse gases, inventory

Quantification of N2O fluxes from soil–plant systems may be biased by the applied gas chromatograph methodology

With regard to measuring nitrous oxide (N2O) emissions from biological sources, there are three most widely adopted methods that use gas chromatograph with an electron capture detector (GC–ECD). They use: (a) nitrogen (N2) as the carrier gas (DN); (b) ascarite as a carbon dioxide (CO2) trap with DN (DN-Ascarite); and (c) a mixture gas of argon and methane as the carrier (AM). Additional methods that use either a mixture of argon and methane (or of CO2 and N2) as a make-up gas with the carrier nitrogen or soda lime (or ascarite) as a CO2 trap with the carrier helium have also been adopted in a few studies. To test the hypothesis that the use of DN sometimes considerably biases measurements of N2O emissions from plants, soils or soil–plant systems, experiments were conducted involving DN, AM and DN-Ascarite. When using DN, a significant relationship appeared between CO2 concentrations and the apparent N2O concentrations in air samples. The use of DN led to significantly overestimated N2O emissions from detached fresh plants in static chamber enclosures. Meanwhile, comparably lower emissions were found when using either the DN-Ascarite or AM methods. When an N2O flux (from a soil or a soil–plant system), measured by DN in combination with sampling from the enclosure of a static opaque chamber, was greater than 200 μg N m−2 h−1, no significant difference was found between DN and DN-Ascarite. When the DN-measured fluxes were within the ranges of <−30, −30–0, 0–30, 30–100 and 100–200 μg N m−2 h−1, significant differences that amounted to −72, −22, 5, 38 and 64 μg N m−2 h−1, respectively, appeared in comparison to DN-Ascarite. As a result, the DN measurements in rice–wheat and vegetable fields overestimated both annual total N2O emissions (by 7–62%, p < 0.05) and direct emission factors for applied nitrogen (by 6–65%). These results suggest the necessity of reassessing the available data determined from DN measurements before they are applied to inventory estimation. Further studies are required to explore appropriate approaches for the necessary reassessment. Our results also imply that the DN method should not be adopted for measuring N2O emissions from weak sources (e.g., with intensities less than 200 μg N m−2 h−1). In addition, we especially do not recommend the use of DN to simultaneously measure N2O and CO2 with the same ECD.

Estimating fire emissions and disparities in boreal Siberia (1998–2002)

In the biomass, soils, and peatlands of Siberia, boreal Russia holds one of the largest pools of terrestrial carbon. Because Siberia is located where some of the largest temperature increases are expected to occur under current climate change scenarios, stored carbon has the potential to be released with associated changes in fire regimes. Our concentration is on estimating a wide range of current and potential emissions from Siberia on the basis of three modeled scenarios. An area burned product of Siberia is introduced, which spans from 1998 through 2002. Emissions models are spatially explicit; therefore area burned is extracted from associated ecoregions for each year. Carbon consumption estimates are presented for 23 unique ecoregions across Siberia, which range from 3.4 to 75.4 t C ha−1 for three classes of severity. Total direct carbon emissions range from the traditional scenario estimate of 116 Tg C in 1999 (6.9 M ha burned) to the extreme scenario estimate of 520 Tg C in 2002 (11.2 M ha burned), which are equivalent to 5 and 20%, respectively, of total global carbon emissions from forest and grassland burning. Our results suggest that disparities in the amount of carbon stored in unique ecosystems and the severity of fire events can affect total direct carbon emissions by as much as 50%. Additionally, in extreme fire years, total direct carbon emissions can be 37–41% greater than in normal fire years, owing to increased soil organic matter consumption. Mean standard scenario estimates of CO2 (555–1031 Tg), CO (43–80 Tg), CH4 (2.4–4.5 Tg), TNMHC (2.2–4.1 Tg), and carbonaceous aerosols (4.6–8.6 Tg) represent 10, 15, 19, 12 and 26%, respectively, of the global estimates from forest and grassland burning. Accounting for smoldering combustion in soils and peatlands results in increases in CO, CH4, and TNMHC and decreases in CO2 emitted from fire events.

Life cycle emission distributions within the economy: implications for life cycle impact assessment.

Refinements of methods for life cycle impact assessment (LCIA) are directed at removing unjustified simplifications and quantifying and reducing uncertainties in results. The amount of uncertainty reduction that is actually achieved through LCIA method refinement depends on the structure of the life cycle inventory model. We investigate the general structure of inventory models using an economic input/output (I/O) life cycle assessment model of the U.S. economy. In particular, we study the results of applying a streamlining algorithm to the I/O LCA model. The streamlining algorithm retains only those "branches" of the process tree that are jointly required to account for a specified fraction of the total impacts upstream of each point in the tree. We examine the implications of these "tree pruning" results for site-informed LCIA. Percentiles are presented for U.S. commodities and several important pollutants, for the share of total upstream emissions contributed by the set of processes in each supply tier, that is, each set of processes that directly supply inputs to another set of processes Capturing at least 90% of the total direct plus upstream emissions for criteria air pollutants and toxic releases for at least 75% of the commodities in the U.S. economy requires full modeling of direct emissions plus the first five supply tiers. The requirements for capturing a high percentage (e.g., >80%) of total emissions vary widely across products or commodities. To capture more than 60% of total emissions for more than half of all commodities requires models with more than 4,000 process instances. To well characterize the total impacts of products, life cycle impact assessment methods must characterize foreground process impacts in a site-informed way and mean impacts of far-removed processes in an unbiased way.

Concentrated Solar Energy as a Diagnostic Tool to Study Materials Under Extreme Conditions

This paper deals with the material testing under extreme conditions, mainly around space programs, using the French CNRS (Centre National de la Recherche Scientifique) solar facilities for planetary entry (Earth, Mars), solar corona in situ exploration, and cryogenic propulsion. For these purposes, different facilities were developed around the various solar concentrators: MESOX (Moyen d’Essai Solaire d’OXydation), for the study of the atomic oxygen recombination at the surface of heated materials and the oxidation kinetics of ceramics under plasma atmospheres up to 2300 K. (Some results are given for several materials.); MEDIASE (Moyen d’Essai et de DIagnostic en Ambiance Spatiale Extre^me), for the thermophysical characterization of thermal shield materials up to 2400°K under high vacuum: mass-loss kinetics, mass spectrometry (neutral and ionic species) and thermo-radiative properties (total or spectral directional emissivity). (Results are presented for various carbon/carbon composite materials.); and DISCO (DISpositif de Caracte´risation Optique), for the measurement of changes in the reflectivity of materials at temperatures up to 2500°K and its correlation with the surface behavior (aging, ablation and oxidation). Results concerning a copper alloy used for the combustion chamber of cryogenic motors are given.

A Simple High-Sensitivity Radiometer in the Infrared for Measurements of the Directional Total Emissivity of Opaque Materials at Near-Ambient Temperatures

A novel device for direct determination of the total directional emissivity of solid surfaces at near-ambient temperatures is described. The method of operation is based on comparing the radiation emitted by the surface with that emitted by a reference. The primary sensor is a solid-state, thermopile detector, and the signal recovery is achieved by phase-sensitive detection techniques, using a mechanical chopper. The device is simple and does not use any cooling. Experimental results are presented using a test sample of clear float glass, kept at 323 K (50°C), with black paint on a float glass substrate as the reference. These results, likely the first for the directional total emissivity of float glass at such low temperatures obtained without cooling, compare well with values in the literature.

Surface EMG-mapping of low back region during different load and investigation conditions

The greenhouse gas (GHG) emissions embodied in 61 different categories of food are used, with information on the diet of different groups of the population (omnivorous, vegetarian and vegan), to calculate the embodied GHG emissions in different dietary scenarios. We calculate that the embodied GHG content of the current UK food supply is 7.4 kg CO2e person−1 day−1, or 2.7 t CO2e person−1 y−1. This gives total food-related GHG emissions of 167 Mt CO2e (1 Mt=106 metric tonnes; CO2e being the mass of CO2 that would have the same global warming potential, when measured over 100 years, as a given mixture of greenhouse gases) for the entire UK population in 2009. This is 27% of total direct GHG emissions in the UK, or 19% of total GHG emissions from the UK, including those embodied in goods produced abroad. We calculate that potential GHG savings of 22% and 26% can be made by changing from the current UK-average diet to a vegetarian or vegan diet, respectively. Taking the average GHG saving from six vegetarian or vegan dietary scenarios compared with the current UK-average diet gives a potential national GHG saving of 40 Mt CO2e y−1. This is equivalent to a 50% reduction in current exhaust pipe emissions from the entire UK passenger car fleet. Hence realistic choices about diet can make substantial differences to embodied GHG emissions.

Nitrous oxide emission from dairy farming systems in the Netherlands

A large part of the nitrogen (N) input in dairy farming systems in the Netherlands is lost from the system via N leaching and volatilization of gaseous N compounds, including the greenhouse gas nitrous oxide (N2O). The aim of the present study was to quantify N2O emission from dairy farming systems in the Netherlands, using a whole-farm approach. A total of 14 N2O sources was identified and emission factors were derived for each of these using the literature. Figures are presented for the amounts of N2O produced/kg herbage N produced (ranging from 4 to 89 g N2O-N kg-1 herbage N), depending on soil type and grassland management. Using Monte Carlo simulations, variations in mean total N2O emissions from the different sources were calculated for 3 model dairy farming systems differing in nutrient management. These different farming systems were chosen to assess the effect of improved nutrient management on total N2O emission. The total direct annual N2O emissions ranged from 15.4 +or-9.4 kg N2O-N/ha for the average dairy farming system in the 1980s to 5.3 +or-2.6 kg N2O-N/ha for a prototype of an economically feasible farming system with acceptable nutrient emissions. Leaching-derived, grazing-derived and fertilizer-derived N2O emissions were the major N2O sources on dairy farming systems. The total direct N2O emissions accounted for 3.2 to 4.6% of the N surplus on the dairy farming systems, suggesting that only a small amount of N was lost as N2O. Total N2O emissions from dairy farming systems in the Netherlands were 13.7+or-5.1 Gg N/year, which is about 35% of the estimated total N2O emission in the Netherlands. It is concluded that improvement of nutrient management of dairy farming systems will significantly decrease the N2O emissions from these systems, and thus the total N2O emission in the Netherlands.

Total emissivity measurements without use of an absolute reference

Total emissivity measurement by ordinary steady state radiometric methods are difficult at low temperature; besides, those methods require an emissivity reference. In this paper, several new periodic methods suitable for total emissivity measurements are presented. First it is shown that the thermal modulation of a sample allows direct emissivity measurements, even at low temperature, with an ordinary equipment involving no cooled vessel. Very accurate measurements have been performed within a few minutes at room temperature, on reflective materials. Second, it is shown that indirect total emissivity measurements are also feasible, provided source and sample temperatures are equal. This condition can be fulfilled with a modulated temperature hemispherical gray surface as IR source, or in a simpler way, with a mobile part of a hemisphere. Third, it is shown that if both sample and source temperatures are modulated, simultaneous direct and indirect measurements can be carried out. This results in an absolute emissivity measurement without reference. As an experimental validation, simultaneous direct and indirect measurements of the total directional emissivity are carried out on three samples at room temperature. Periodic radiometry methods are found to be reliable and accurate, emission and reflection measurements giving the same result.

Method and apparatus for determination of the total directional emissivity of opaque materials in the temperature range 300 to 600 K

A novel device for measurements of the normal and directional total emissivity of solid surfaces in the range 300–600 K is described. The measurements were performed using the radiation comparison method. A novel black-body radiation source is used as a standard. The detection system consists of a pyroelectric head, a preamplifier, a chopper, and a matching lock-in amplifier with analog recorder ourput. The device is simple and well suited for routine measurements. Comparison of our results with those of previous investigations shows a good agreement.