| 1. |
- Andersen, J. K., et al.
(författare)
-
Quantification of Greenhouse Gas Emissions from Windrow Composting of Garden Waste
- 2010
-
Ingår i: Journal of Environmental Quality. - : Wiley. - 0047-2425. ; 39:2, s. 713-724
-
Tidskriftsartikel (refereegranskat)abstract
- Microbial degradation of organic wastes entails the production of various gases such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and carbon monoxide (CO). Some of these gases are classified as greenhouse gases (GHGs), thus contributing to climate change. A study was performed to evaluate three methods for quantifying GHG emissions from central composting of garden waste. Two small-scale methods were used at a windrow composting facility: a static flux chamber method and a funnel method. Mass balance calculations based on measurements of the C content in the in- and out-going material showed that 91 to 94% of the C could not be accounted for using the small-scale methods, thereby indicating that these methods significantly underestimate GHG emissions. A dynamic plume method (total emission method) employing Fourier Transform Infra Red (FTIR) absorption spectroscopy was found to give a more accurate estimate of the GHG emissions, with CO2 emissions measured to be 127 +/- 15% of the degraded C. Additionally, with this method, 2.7 +/- 0.6% and 0.34 +/- 0.16% of the degraded C was determined to be emitted as CH4 and CO. In this study, the dynamic plume method was a more effective tool for accounting for C losses and, therefore, we believe that the method is Suitable for measuring GHG emissions from composting facilities. The total emissions were found to be 2.4 +/- 0.5 kg CH4-C Mg-1 wet waste (ww) and 0.06 +/- 0.03 kg N2O-N Mg-1 ww from a facility treating 15,540 Mg of garden waste yr(-1), or 111 +/- 30 kg CO2-equivalents Mg-1 ww.
|
|
| 2. |
- Börjesson, Gunnar, et al.
(författare)
-
A national landfill methane budget for Sweden based on field measurements, and an evaluation of IPCC models
- 2009
-
Ingår i: Tellus, Series B: Chemical and Physical Meteorology. - : Stockholm University Press. - 1600-0889 .- 0280-6509. ; 61:2, s. 424-435
-
Tidskriftsartikel (refereegranskat)abstract
- Seven Swedish landfills were investigated from 2001 to 2003. On each landfill, a measure of the total methane production was calculated from data on: (1) methane emissions (leakage); (2) methane oxidation and (3) from gas recovery. Methane emissions were determined via a tracer gas (N2O) release-based remote sensing method. N2O and CH4 were measured with an Fourier Transform infrared detector at a distance of more than 1 km downwind from the landfills. Methane oxidation in the landfill covers was measured with the stable carbon isotope method. The efficiency in gas recovery systems proved to be highly variable, but on an average, 51% of the produced landfill gas was captured. A first-order decay model, based on four fractions (waste from households and parks, sludges and industrial waste), showed that the use of a degradable organic carbon fraction (DOCf) value of 0.54, in accordance with the default value for DOCf of 0.50 in the latest IPCC model, gave an emission estimate similar to the official national reports.
|
|
| 3. |
- Börjesson, Gunnar, et al.
(författare)
-
Methane oxidation in Swedish landfills qnantified with the stable carbon isotope technique in combination with an optical method for emitted methane
- 2007
-
Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 41:19, s. 6684-6690
-
Tidskriftsartikel (refereegranskat)abstract
- Methane budgets (production = emissions + oxidation + recovery) were estimated for six landfill sites in Sweden. Methane oxidation was measured in downwind plumes with a stable isotope technique (Chariton, J. P., et al., Environ. Sci. TechnoL 1999, 33, 3755-3760.) Positions in plumes for isotope sampling as well as methane emissions were determined with an optical instrument (Fourier Transform InfraRed) in combination with N2O as tracer gas (Galle, B., et al., Environ. Sci. TechnoL 2001, 35,21-25.) Two landfills had been closed for years prior to the measurements, while four were active. Measurements at comparable soil temperatures showed that the two closed landfills had a significantly higher fraction of oxidized methane (38-42% of emission) relative to the four active landfills (4.6-15% of emission). These results highlight the importance of installing and maintaining effective landfill covers and also indicate that substantial amounts of methane escape from active landfills. Based on these results we recommend that the IPCC default values for methane oxidation in managed landfills could be set to 10% for active sites and 20% for closed sites. Gas recovery was found to be highly variable at the different sites, with values from 14% up to 65% of total methane production. The variance can be attributed to different waste management practices.
|
|
| 4. |
|
|
| 5. |
- de Foy, B., et al.
(författare)
-
Modelling constraints on the emission inventory and on vertical dispersion for CO and SO2 in the Mexico City Metropolitan Area using Solar FTIR and zenith sky UV spectroscopy
- 2007
-
Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 7, s. 781-801
-
Tidskriftsartikel (refereegranskat)abstract
- Emissions of air pollutants in and around urban areas lead to negative health impacts on the population. To estimate these impacts, it is important to know the sources and transport mechanisms of the pollutants accurately. Mexico City has a large urban fleet in a topographically constrained basin leading to high levels of carbon monoxide ( CO). Large point sources of sulfur dioxide (SO2) surrounding the basin lead to episodes with high concentrations. An Eulerian grid model (CAMx) and a particle trajectory model ( FLEXPART) are used to evaluate the estimates of CO and SO2 in the current emission inventory using mesoscale meteorological simulations from MM5. Vertical column measurements of CO are used to constrain the total amount of emitted CO in the model and to identify the most appropriate vertical dispersion scheme. Zenith sky UV spectroscopy is used to estimate the emissions of SO2 from a large power plant and the Popocatepetl volcano. Results suggest that the models are able to identify correctly large point sources and that both the power plant and the volcano impact the MCMA. Modelled concentrations of CO based on the current emission inventory match observations suggesting that the current total emissions estimate is correct. Possible adjustments to the spatial and temporal distribution can be inferred from model results. Accurate source and dispersion modelling provides feedback for development of the emission inventory, verification of transport processes in air quality models and guidance for policy decisions.
|
|
| 6. |
- De Gouw, J. A., et al.
(författare)
-
Airborne Measurements of Ethene from Industrial Sources Using Laser Photo-Acoustic Spectroscopy
- 2009
-
Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 43:7, s. 2437-2442
-
Tidskriftsartikel (refereegranskat)abstract
- A laser photoacoustic spectroscopy (LPAS) instrument was developed and used for aircraft measurements of ethene from industrial sources near Houston, Texas. The instrument provided 20 s measurements with a detection limit of less than 0.7 ppbv. Data from this instrument and from the GC-FID analysis of air samples collected in flight agreed within 15% on average. Ethene fluxes from the Mt. Belvieu chemical complex to the northeast of Houston were quantified during 10 different flights. The average flux was 520 +/- 140 kg h(-1) in agreement with independent results from solar occultation flux (SOF) measurements, and roughly an order of magnitude higher than regulatory emission inventories indicate. This study shows that ethene emissions are routinely at levels that qualify as emission upsets, which need to be reported to regional air quality managers.
|
|
| 7. |
|
|
| 8. |
- Johansson, John, 1982, et al.
(författare)
-
Emission measurements of alkenes, alkanes, SO2, and NO2 from stationary sources in Southeast Texas over a 5 year period using SOF and mobile DOAS
- 2014
-
Ingår i: Journal of Geophysical Research. - : American Geophysical Union (AGU). - 0148-0227 .- 2156-2202 .- 2169-897X. ; 119:4, s. 1973-1991
-
Tidskriftsartikel (refereegranskat)abstract
- A mobile platform for flux measurements of VOCs (alkanes and alkenes), SO2, and NO2 emissions using the Solar Occultation Flux (SOF) method and mobile differential optical absorption spectroscopy (DOAS) was used in four different studies to measure industrial emissions. The studies were carried out in several large conglomerates of oil refineries and petrochemical industries in Southeast and East Texas in 2006, 2009, 2011, and 2012. The measured alkane emissions from the Houston Ship Channel (HSC) have been fairly stable between 2006 and 2011, averaging about 11,500kg/h, while the alkene emissions have shown greater variations. The ethene and propene emissions measured from the HSC were 1511kg/h and 878kg/h, respectively, in 2006, while dropping to roughly 600kg/h for both species in 2009 and 2011. The results were compared to annual inventory emissions, showing that measured VOC emissions were typically 5-15 times higher, while for SO2 and NO2 the ratio was typically 0.5-2. AP-42 emission factors were used to estimate meteorological effects on alkane emissions from tanks, showing that these emissions may have been up to 35-45% higher during the studies than the annual average. A more focused study of alkene emissions from a petrochemical complex in Longview in 2012 identified two upset episodes, and the elevation of the total emissions during the measurement period due to the upsets was estimated to be approximately 20%. Both meteorological and upset effects were small compared to the factor of 5-15, suggesting that VOC emissions are systematically and substantially underestimated in current emission inventories.
|
|
| 9. |
- Johansson, John, 1982, et al.
(författare)
-
Quantitative measurements and modeling of industrial formaldehyde emissions in the Greater Houston area during campaigns in 2009 and 2011
- 2014
-
Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 119:7, s. 4303-4322
-
Tidskriftsartikel (refereegranskat)abstract
- A sensitive Mobile differential optical absorption spectroscopy (DOAS) system with real-time evaluation capability and HCHO detection limit of 3 ppb over 100 m has been developed. The system was operated together with a Solar Occultation Flux system for large-scale vertical flux measurements of HCHO, NO2, SO2, and VOCs in the Houston-Galveston-Brazoria area during two studies, in 2009 (Study of Houston Atmospheric Radical Precursors campaign) and in 2011 (Air Quality Research Program study). Both in 2009 and 2011, HCHO plumes from five separate local sources in Texas City, Mont Belvieu, and Houston Ship Channel (HSC) were repeatedly detected using Mobile DOAS with emissions varying between 6 and 40 kg/h. In many cases significant alkene emissions were detected simultaneously with the HCHO plumes. Furthermore, in 2011 two additional sources were observed in Texas City and in HSC, with 10 kg/h and 31 kg/h HCHO, respectively. A plume chemistry model was applied to 13 cases to investigate whether the detected HCHO was emitted directly from the industries or was produced by photochemical degradation of VOCs. The model results showed that on average 90% of the detected HCHO was of primary origin and the photochemical production contributed more than 10% in only three cases. Based on the repeatability, it is likely that the most significant HCHO sources in the area are included in this study with an overall emission of 120 kg/h. On a regional scale, this emission is small compared to the secondary HCHO formed from oxidation of reactive VOCs emitted from the same industries, estimated to be an order of magnitude higher.
|
|
| 10. |
- Mellqvist, Johan, 1965, et al.
(författare)
-
Characterization of Air Toxics and Greenhouse Gas Emission Sources and Their Impacts on Community-Scale Air Quality Levels in Disadvantaged Communities
- 2021
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Methane (CH4) is an important short-lived climate pollutant and contributes roughly 9 percent to California's statewide GHG emissions. California has passed several climate legislations, including AB 1383 (Lara, 2015-16) and AB 1496 (Thurmond, 2015-16), which require CARB to use the best available scientific and technical methods to monitor and measure high-emission CH4 hotspots within the State, to use the information to update relevant programs and policies, and to implement a climate mitigation program to reduce statewide CH4 emissions by 40 percent below the 2013 levels. Furthermore, certain industrial emissions sources of CH4, such as oil and gas facilities, are known to co-emit air toxics that have adverse health effects, and their impacts are more pronounced in communities near those sources than they are regionally. Therefore, it is important to understand these emissions, and conduct enhanced community-scale monitoring for air toxics in near-source communities, many of which may be disadvantaged. Additionally, scientific studies have suggested that national and statewide CH4 emissions inventories may be underestimated, and real-world emissions measurements may be useful to evaluate source-level emission estimates and understand emission behaviors. The objectives of this research study are to characterize air toxics and GHG emission behavior from a variety of complex emission sources, and to study the impact of these sources on air quality levels in disadvantaged communities. The project utilized a state-of-the-art research-grade mobile monitoring laboratory equipped with advanced monitoring instruments to characterize and quantify the air toxics and GHG emission behavior from complex air pollution sources, as well as their air pollution impacts on nearby communities. Through four regional campaigns across California, the project measured facility-level emissions of CH4, alkanes, benzene, BTEX (benzene, toluene, ethylbenzene and xylene), ammonia (NH3), and sulfur and nitrogen oxides (SOX and NOX) from a variety of sources, including refineries, petrochemical facilities, oil storage, port activities, landfills, oil and gas production and dairy farms, and tracked the air pollution impact of the emission plumes in neighboring communities. This study found that the observed emissions, which are representative of emissions at a single point in time, were greater than inventory factors and models, representative of overall averages, for many of the volatile organic compounds (VOC). Alkane emissions from five large refinery areas in the Bay Area were on average 2.5 times the reported emission, and CH4 emissions were roughly 3 times the reported emissions, while total NOX emissions were comparable to the inventory estimates. Similarly, alkane and CH4 emissions from oil and gas fields in the San Joaquin Valley, which accounts for more than 70 percent of California's oil and gas production capacity, were 10 and 2 times higher than production-based emission factors, respectively. On the other hand, CH4 and NH3 emissions from roughly 20 dairy farms were 50 percent and 100 percent higher than annual emission factor, respectively, some of which were due to diurnal variations. These discrepancies suggest more work is needed to ascertain whether these point-in-time measurements are representative of annual averages, and if emissions are indeed higher than standard methods suggest. The measurements in the Richmond community showed VOC concentrations dominated by alkanes from the port area. Community-scale ground-level concentrations of BTEX were on average low in all studies. The research study demonstrated the use of advanced techniques for facility-wide emission measurements and community monitoring of air toxics, and suggests that a combination of mobile and fixed continuous measurements may provide useful information to understand source emissions, and their impacts on communities. The source-level emission data may be useful to understand emissions from complex emission sources (including large point sources, distributed emission sources, area sources). The community-scale measurement effort will provide the ability to conduct community-scale air toxics measurements in real-time, with information on air pollution hotspots in various disadvantaged communities and useful screening information to identify potential sources for prioritizing air pollution mitigation efforts. https://ww3.arb.ca.gov/research/single-project.php?row_id=67028
|
|
