Monitoring agricultural burning in the Mississippi River Valley region from the moderate resolution imaging spectroradiometer (MODIS)

The 2003 active fire observations from the Moderate Resolution Imaging Spectroradiometer (MODIS), on board NASA's Terra and Aqua satellites, were analyzed to assess burning activity in the cropland areas of the Mississippi River Valley region. Agricultural burning was found to be an important contributor to fire activity in this region, accounting for approximately one-third of all burning. Agricultural fire activity showed two seasonal peaks: the first, smaller peak, occurring in June during the spring harvesting of wheat; and the second, bigger peak, in October during the fall harvesting of rice and soy. The seasonal signal in agricultural burning was predominantly evident in the early afternoon MODIS Aqua fire detections. A strong diurnal agricultural fire signal was prevalent during the fall harvesting months, as suggested by the substantially higher number (approximately 3.5 times) of fires detected by MODIS Aqua in the early afternoon, compared with those detected by MODIS Terra in the morning. No diurnal variations in agricultural fire activity were apparent during the springtime wheat-harvesting season. The seasonal and diurnal patterns in agricultural fire activity detected by MODIS are supported by known crop management practices in this region. MODIS data provide an important means to characterize and monitor agricultural fire dynamics and management practices.     

Ambient air quality changes after stubble burning in rice–wheat system in an agricultural state of India

Ground-based ambient air monitoring was conducted to assess the contribution of crop residue burning of wheat (Triticum aestivum) and rice (Oriza sativa) at different locations in three districts (Kaithal, Kurukshetra, and Karnal) of the agricultural state of Haryana in India for two successive years (2016 and 2017). The Air Quality Index (AQI) and concentration of primary pollutants (SO_x, NO_x, and PM_2.5) were determined in rice and wheat crop season, for burning and non-burning periods. During crop residue burning periods, concentrations of SO_x, NO_x, and PM_2.5 were exceeded the NAAQS values by 78%, 71%, and 53%, respectively. A significant increase in SO_x (4.5 times), NO_x (3.8 times), and PM_2.5 concentration (3.5 times) was observed in stubble burning periods as compared to pre-burning (p < 0.05). A positive and significant correlation among the three pollutant concentrations was observed (p < 0.01). The AQI of KA site in Karnal district fell in severely polluted category during 2016 for rice as well as wheat residue burning period, and of KK site in Kaithal during wheat residue burning in year 2017. Results of present study indicate a remarkable increase in pollutant concentration (SO_x, NO_x, and PM_2.5) during the crop residue burning periods. To the best of our knowledge, the outcomes of present study in this region have not been reported in earlier reports. Hence, there is an urgent need to curb air pollution by adopting sustainable harvesting technologies and management of residues.

     

Annual and seasonal variability of ambient aerosols over an urban region in western India

Annual and seasonal variabilities in source contribution to total suspended particles (TSP) measured over an urban location in western India, Ahmedabad between May 2000 and January 2003 are examined in this study. Positive matrix factorization (PMF) resolved six factors including airborne regional dust, calcium carbonate rich dust, biomass burning/vehicular emissions, secondary nitrate/sulfate, marine aerosol, and smelter. In this study, non-parametric statistical tests including the Kruskal–Wallis analysis of variance (K–W ANOVA) and Spearman rank correlation (ρ) test were used to assess the annual and seasonal variations in factor contributions, and the influence of meteorology on these contributions, respectively. None of the factor contributions exhibited annual variations except airborne regional dust, and biomass burning/vehicular emissions factors. All of the factors exhibited seasonal variations. Several factor monsoon (July–September) median concentrations were significantly different from one or more of the other season medians. In general, it appeared that meteorological factors played a role in establishing the seasonal behavior of factor contributions. Factor contributions exhibited low to moderate correlations with meteorological parameters such as temperature, relative humidity, wind direction, and wind speed. Amongst all of the relationships, marine aerosol factor was reasonably well correlated with relative humidity (ρ = 0.73) and wind direction (ρ = 0.73) during the pre-monsoon season (March–May). This observation suggests that the aerosol transported by moisture laden winds from the Arabian sea contribute to this factor. The airborne regional dust factor was also moderately correlated with wind speed (ρ = 0.70) during the post-monsoon season. This relationship indicates that high regional dust concentrations are favored by high wind speeds and the resultant increase in dispersion.     

Ambient air quality during wheat and rice crop stubble burning episodes in Patiala

Open crop stubble burning events were observed in and around Patiala city, India. A ground level study was deliberated to analyze the contribution of wheat (Triticum aestivum) and rice (Oriza sativa) crop stubble burning practices on concentration levels of aerosol, SO₂ and NO₂ in ambient air at five different sites in and around Patiala city covering agricultural, commercial and residential areas. Aerosols were collected on GMF/A and QMF/A (Whatman) sheets for a 24 h period throughout the year in 2007. Simultaneously, sampling of SO₂ and NO₂ was conducted and results obtained during stubble burning periods were compared to the non-stubble burning periods. Results clearly pointed out a distinct increase in aerosol, SO₂ and NO₂ levels during the crop stubble burning periods.     

Direct emission factor for N2O from rice–winter wheat rotation systems in southeast China

A field experiment was conducted in a rice–winter wheat rotation agroecosystem to quantify the direct emission of N₂O for synthetic N fertilizer and crop residue application in the 2002–2003 annual cycle. There was an increase in N₂O emission accompanying synthetic N fertilizer application. Fertilizer-induced emission factor for N₂O (FIE) averaged 1.08% for the rice season, 1.49% for the winter wheat season and 1.26% for the whole annual rotation cycle. The annual background emission of N₂O totaled 4.81 kg N₂O–N ha⁻¹, consisting of 1.24 kg N₂O–N ha⁻¹ for rice, 3.11 kg N₂O–N ha⁻¹ for wheat seasons. When crop residue and synthetic N fertilizer were both applied in the fields, crop residue-induced emission factor for N₂O (RIE) was estimated as well. When crop residue was retained at the rate of 2.25 and 4.50 t ha⁻¹ for each season, the RIE averaged 0.64% and 0.27% for the whole annual rotation cycle, respectively. Based on available multi-year data of N₂O emissions over the whole rice–wheat rotation cycle at 3 sites in southeast China, the FIE averaged 1.02% for the rice season, 1.65% for the wheat season. On the whole annual cycle, the FIE for N₂O ranged from 1.05% to 1.45%, with an average of 1.25%. Annual background emission of N₂O averaged 4.25 kg ha⁻¹, ranging from 3.62 to 4.87 kg ha⁻¹. It is estimated that annual N₂O emission in paddy rice-based agroecosystem amounts to 169 Gg N₂O–N in China, accounting for 26–60% of the reported estimates of total emission from croplands in China.     

Aerosol radiative forcing over the Indo-Gangetic plains during major dust storms

Indo-Gangetic (IG) alluvial plains, one of the largest river basins in the world, suffers from the long range transport of mineral dust from the western arid and desert regions of Africa, Arabia and Rajasthan during the summer (pre-monsoon season, April–June). These dust storms influence the aerosol optical depth (AOD) across the IG plains. The Kanpur AERONET (Aerosol Robotic Network) station and Moderate Resolution Imaging Spectro-radiometer (MODIS) data show pronounced effect on the aerosol optical properties and aerosol size distribution during major dust storm events over the IG plains that have significant effect on the aerosol radiative forcing (ARF). The multi-band AOD, from AERONET and MODIS, show contrasting changes in wavelength dependency over dust affected regions. A time collocated (±30 min) validation of AERONET AOD with MODIS Terra (level 2 swath product) over Kanpur, at a common wavelength of 550 nm for the period 2001–2005 show moderate correlation (R²∼0.6) during the summer season. The average surface forcing is found to change by −23 W m⁻² during dust events and the top of the atmosphere (TOA) forcing change by −11 W m⁻² as compared to the non-dusty clear-sky days. A strong correlation is found between AOD at 500 nm and the ARF. At surface, the correlation coefficient between AOD and ARF is found to be high (R²=0.925) and is found to be moderate (R²=0.628) at the TOA. The slope of the regression line gives the aerosol forcing efficiency at 500 nm of about −46±2.6 W m⁻² and −17±2.5 W m⁻² at the surface and the TOA, respectively. The ARF is found to increase with the advance of the dry season in conjunction with the gradual rise in AOD (at 500 nm) from April (0.4–0.5) to June (0.6–0.7) over the IG plains.     

Residues and dynamics of pymetrozine in rice field ecosystem

The fate of pymetrozine was studied in rice field ecosystem, and a simple and reliable analytical method for determination of pymetrozine in soil, rice straw, paddy water and brown rice was developed. Pymetrozine residues were extracted from samples, cleaned up by solid phase extraction (SPE) and then determined by high-performance liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS). The average recovery was 81.2-88.1% from soil, 83.4-88.6% from rice straw, 87.3-94.1% from paddy water and 82.9-85.3% from brown rice. The relative standard deviation (RSD) was less than 15%. The limits of detection (LODs) of pymetrozine calculated as a sample concentration were 0.0003 mg kg⁻¹ (mg L⁻¹) for soil and paddy water, 0.001 mg kg⁻¹ for brown rice and rice straw. The results of kinetics study of pymetrozine residue showed that pymetrozine degradation in water, soil, and rice straw coincided with C = 0.194e^−0.986t, C = 0.044e^−0.099t, and C = 0.988e^−0.780t, respectively; the half-lives were about 0.70 d, 7.0 d and 0.89 d, respectively. The degradation rate of pymetrozine in water was the fastest, followed by rice straw. The highest final pymetrozine residues in brown rice were 0.01 mg kg⁻¹, which was lower than the EU’s upper limit of 0.02 mg kg⁻¹ in rice. Therefore, a dosage of 300-600 g a.i.hm⁻² was recommended, which could be considered as safe to human beings and animals.     

Seasonal and monthly variations of columnar aerosol optical properties over east Asia determined from multi-year MODIS,LIDAR, and AERONET Sun/sky radiometer measurements

Multi-year records of MODIS, micro-pulse lidar (MPL), and aerosol robotic network (AERONET) Sun/sky radiometer measurements were analyzed to investigate the seasonal, monthly and geographical variations of columnar aerosol optical properties over east Asia. Similar features of monthly and seasonal variations were found among the measurements, though the observational methodology and periods are not coincident. Seasonal and monthly cycles of MODIS-derived aerosol optical depth (AOD) over east Asia showed a maximum in spring and a minimum in autumn and winter. Aerosol vertical extinction profiles measured by MPL also showed elevated aerosol loads in the middle troposphere during the spring season. Seasonal and spatial distributions were related to the dust and anthropogenic emissions in spring, but modified by precipitation in July–August and regional atmospheric dispersion in September–February. All of the AERONET Sun/sky radiometers utilized in this study showed the same seasonal and monthly variations of MODIS-derived AOD. Interestingly, we found a peak of monthly mean AOD over industrialized coastal regions of China and the Yellow Sea, the Korean Peninsula, and Japan, in June from both MODIS and AERONET Sun/sky radiometer measurements. Especially, the maximum monthly mean AOD in June is more evident at the AERONET urban sites (Beijing and Gwangju). This AOD June maximum is attributable to the relative contribution of various processes such as stagnant synoptic meteorological patterns, secondary aerosol formation, hygroscopic growth of hydrophilic aerosols due to enhanced relative humidity, and smoke aerosols by regional biomass burning.     

Characterization of atmospheric aerosols for organic tarry matter and combustible matter during crop residue burning and non-crop residue burning months in Northwestern region of India

Aerosol (total suspended particulate) samples collected at three diverse locations (urban-commercial, semi-urban and rural-agricultural) in Patiala, India were analyzed for loss on ignition (LOI) and organic tarry matter (OTM) content in ambient air during crop residue burning (CRB) episodes and non-crop residue burning (NCRB) months in 2006–2007. Results showed high levels of LOI and OTM during wheat and rice crop residue-burning periods at all the sites. Higher levels were obtained during rice crop residue-burning period as compared to the wheat residue-burning period. At semi-urban site, LOI varied between 53 ± 36 μg m^?3 and 257 ± 14 μg m^?3 constituting 38–78% (w/w) part of the aerosols whereas levels of OTM varied between 0.98 ± 0.11 μg m^?3 and 7.93 ± 2.76 μg m^?3 comprising 0.42–3.28% (w/w) fraction. At rural-agricultural area site, levels of LOI varied between 86 ± 40 μg m^?3 and 293 ± 70 μg m^?3 comprising 27–84% (w/w), whereas OTM levels varied between 1.31 ± 0.64 μg m^?3 and 10.09 ± 6.56 μg m^?3 constituting 0.83–2.42% (w/w) fraction of the aerosols. At urban-cum-commercial site, levels of LOI and OTM varied between 48 ± 23 μg m^?3 and 281 ± 152 μg m^?3 and 2.53 ± 1.23 μg m^?3 and 17.40 ± 8.50 μg m^?3, constituting 24–62% (w/w) part of the aerosols, respectively. Results also indicated that OTM and LOI were integral parts of aerosols and their concentrations were influenced by the crop residue burning practices with incorporated effect of vehicular activities in Patiala.     

Aerosol optical and physical properties during winter monsoon pollution transport in an urban environment

We analysed aerosol optical and physical properties in an urban environment (Kolkata) during winter monsoon pollution transport from nearby and far-off regions. Prevailing meteorological conditions, viz. low temperature and wind speed, and a strong downdraft of air mass, indicated weak dispersion and inhibition of vertical mixing of aerosols. Spectral features of WinMon aerosol optical depth (AOD) showed larger variability (0.68–1.13) in monthly mean AOD at short-wavelength (SW) channels (0.34–0.5 μm) compared to that (0.28–0.37) at long-wavelength (LW) channels (0.87–1.02 μm), thereby indicating sensitivity of WinMon AOD to fine aerosol constituents and the predominant contribution from fine aerosol constituents to WinMon AOD. WinMon AOD at 0.5 μm (AOD _{0. 5}) and Angstrom parameter ( α) were 0.68–0.82 and 1.14–1.32, respectively, with their highest value in December. Consistent with inference from spectral features of AOD, surface aerosol loading was primarily constituted of fine aerosols (size 0.23–3 μm) which was 60–70 % of aerosol 10- μm (size 0.23–10 μm) concentration. Three distinct modes of aerosol distribution were obtained, with the highest WinMon concentration at a mass median diameter (MMD) of 0.3 μm during December, thereby indicating characteristics of primary contribution related to anthropogenic pollutants that were inferred to be mostly due to contribution from air mass originating in nearby region having predominant emissions from biofuel and fossil fuel combustion. A relatively higher contribution from aerosols in the upper atmospheric layers than at the surface to WinMon AOD was inferred during February compared to other months and was attributed to predominant contribution from open burning emissions arising from nearby and far-off regions. A comparison of ground-based measurements with Moderate Resolution Imaging Spectroradiometer (MODIS) data showed an underestimation of MODIS AOD and α values for most of the days. Discrepancy in relative distribution of fine and coarse mode of MODIS AOD was also inferred.     

Remote sensing-based estimates of annual and seasonal emissions from crop residue burning in the contiguous United States

Crop residue burning is an extensive agricultural practice in the contiguous United States (CONUS). This analysis presents the results of a remote sensing-based study of crop residue burning emissions in the CONUS for the time period 2003-2007 for the atmospheric species of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), nitrogen dioxide (NO2, sulfur dioxide (SO2), PM2.5 (particulate matter [PM] < or = 2.5 microm in aerodynamic diameter), and PM10 (PM < or = 10 microm in aerodynamic diameter). Cropland burned area and associated crop types were derived from Moderate Resolution Imaging Spectroradiometer (MODIS) products. Emission factors, fuel load, and combustion completeness estimates were derived from the scientific literature, governmental reports, and expert knowledge. Emissions were calculated using the bottom-up approach in which emissions are the product of burned area, fuel load, and combustion completeness for each specific crop type. On average, annual crop residue burning in the CONUS emitted 6.1 Tg of CO2, 8.9 Gg of CH4, 232.4 Gg of CO, 10.6 Gg of NO2, 4.4 Gg of SO2, 20.9 Gg of PM2.5, and 28.5 Gg of PM10. These emissions remained fairly consistent, with an average interannual variability of crop residue burning emissions of +/- 10%. The states with the highest emissions were Arkansas, California, Florida, Idaho, Texas, and Washington. Most emissions were clustered in the southeastern United States, the Great Plains, and the Pacific Northwest. Air quality and carbon emissions were concentrated in the spring, summer, and fall, with an exception because of winter harvesting of sugarcane in Florida, Louisiana, and Texas. Sugarcane, wheat, and rice residues accounted for approximately 70% of all crop residue burning and associated emissions. Estimates of CO and CH4 from agricultural waste burning by the U.S. Environmental Protection Agency were 73 and 78% higher than the CO and CH4 emission estimates from this analysis, respectively. This analysis also showed that crop residue burning emissions are a minor source of CH4 emissions (< 1%) compared with the CH4 emissions from other agricultural sources, specifically enteric fermentation, manure management, and rice cultivation.     

Development of the crop residue and rangeland burning in the 2014 National Emissions Inventory using information from multiple sources

Biomass burning has been identified as an important contributor to the degradation of air quality because of its impact on ozone and particulate matter. One component of the biomass burning inventory, crop residue burning, has been poorly characterized in the National Emissions Inventory (NEI). In the 2011 NEI, wildland fires, prescribed fires, and crop residue burning collectively were the largest source of PM_2.5. This paper summarizes our 2014 NEI method to estimate crop residue burning emissions and grass/pasture burning emissions using remote sensing data and field information and literature-based, crop-specific emission factors. We focus on both the postharvest and pre-harvest burning that takes place with bluegrass, corn, cotton, rice, soybeans, sugarcane and wheat. Estimates for 2014 indicate that over the continental United States (CONUS), crop residue burning excluding all areas identified as Pasture/Grass, Grassland Herbaceous, and Pasture/Hay occurred over approximately 1.5 million acres of land and produced 19,600 short tons of PM_2.5. For areas identified as Pasture/Grass, Grassland Herbaceous, and Pasture/Hay, biomass burning emissions occurred over approximately 1.6 million acres of land and produced 30,000 short tons of PM_2.5. This estimate compares with the 2011 NEI and 2008 NEI as follows: 2008: 49,650 short tons and 2011: 141,180 short tons. Note that in the previous two NEIs rangeland burning was not well defined and so the comparison is not exact. The remote sensing data also provided verification of our existing diurnal profile for crop residue burning emissions used in chemical transport modeling. In addition, the entire database used to estimate this sector of emissions is available on EPA’s Clearinghouse for Inventories and Emission Factors (CHIEF, http://www3.epa.gov/ttn/chief/index.html).Implications: Estimates of crop residue burning and rangeland burning emissions can be improved by using satellite detections. Local information is helpful in distinguishing crop residue and rangeland burning from all other types of fires.     

Factors affecting ammonia volatilisation from a rice-wheat rotation system

Some of the major factors influencing ammonia volatilisation in a rice wheat rotation system were studied. A continuous airflow enclosure method was used to measure NH3 volatilisation in a field experiment at an agricultural college in Jiangsu Province. The five treatments comprised application rates of 0, 100, 200 or 300 kg N ha(-1) as urea, per growing season with rice straw amendment when wheat was sown, and 200 kg N ha(-1) without rice straw amendment. There were three replicates in a randomised block design. Ammonia volatilisation was measured immediately after urea application in the three consecutive years 1995 to 1997. The results show that N losses through NH3 volatilisation accounted for 4-19% of N applied during the wheat growing season and for 5-11% during the rice growing season. Ammonia volatilisation was affected significantly by soil moisture and temperature before and after fertiliser application during the wheat growing season. The ratio of volatilised NH3-N to applied N after urea application during the rice growing season was as follows: top-dressing at the onset of tillering > top-dressing at the start of the booting stage > basal fertilization. The results also show that the amount of N lost through NH3 volatilisation increased with increasing N application rate, but the ratio to applied N was not affected significantly by N application rate. Amendment with rice straw had no significant effect on NH3 volatilisation.     

Size distribution of particles emitted from grass fires in the Northern Territory,Australia

This study investigated particle size distributions from the burning of several grass species, under controlled laboratory conditions, and also in the field, conducted during the dry season in the Northern Territory, Australia. The laboratory study simulated conditions such as burning phases and burning rate, and particle diameter differed depending on the burning conditions. Under fast burning conditions, smaller particles were produced with a diameter in the range of 30–60 nm, while larger particles, with a diameter between 60 and 210 nm, were produced during slow burning. The airborne field measurements of biomass particles found that under the boundary layer most of the early dry season (EDS) particles came from fresh smokes with a count median diameter (CMD) of 83±13 nm, and most of the late dry season (LDS) particles came from aged smokes with a CMD of 127±6 nm. Vertical profiles of CMD showed that smaller particles were found higher within the atmosphere. These measurements provide insight into the scientific understanding of the properties of biomass burning particles in the Northern Territory, Australia.     

Methane emission from fields with three various rice straw treatments in Taiwan paddy soils

Flooded rice fields are one of the major biogenic methane sources. In this study, the effects of straw residual treatments on methane emission from paddy fields were discussed. The experimental field was located at Tainan District Agricultural Improvement Station in Chia-Yi county (23 degrees 25'08'N, 120degrees16'26'E) of southern Taiwan throughout the first and the second crop seasons in 2000. The seasonal methane fluxes in the first crop season with rice stubble removed, rice straw burned and rice straw incorporated were 4.41, 3.78 and 5.27 g CH4 m(-2), and the values were 32.8, 38.9 and 75.1 g CH4 m(-2) in the second crop season, respectively. In comparison of three management methods of rice straw residue, the incorporation of rice straw residue should show a significant tendency for enhancing methane emission in the second crop season. Moreover, stubble removed and straw burned treatments significantly reduced CH4 emissions by 28 approximately 56% emissions compared to straw incorporated plot. Concerning for air quality had led to legislation restricting rice straw burning, removing of rice stubble might be an appropriate methane mitigation strategy in Taiwan paddy soils.     

Potential of conservation agriculture modules for energy conservation and sustainability of rice-based production systems of Indo-Gangetic Plain region

Rice-based cropping systems are the most energy-intensive production systems in South Asia. Sustainability of the rice-based cropping systems is nowadays questioned with declining natural resource base, soil degradation, environmental pollution, and declining factor productivity. As a consequence, the search for energy and resource conservation agro-techniques is increasing for sustainable and cleaner production. Conservation agriculture (CA) practices have been recommended for resource conservation, soil health restoration and sustaining crop productivity. The present study aimed to assess the different CA modules in rice-based cropping systems for energy conservation, energy productivity, and to define energy-economic relations. A field experiment consisted of four different tillage-based crop establishment practices (puddled-transplanted rice followed by (fb) conventional-till maize/wheat (CTTPR-CT), non-puddled transplanted rice fb zero-till maize/wheat (NPTPR-ZT), zero-till transplanted rice fb zero-till maize/wheat (ZTTPR-ZT), zero-till direct-seeded rice fb zero-till maize/wheat (ZTDSR-ZT)), with two residue management treatments (residue removal, residue retention) in rice–wheat and rice–maize rotations were evaluated for energy budgeting and energy-economic relations. Conservation-tillage treatments (NPTPR-ZT, ZTTPR-ZT, and ZTDSR-ZT) reduced the energy requirements over conventional tillage treatments, with the greater reduction in ZTTPR-ZT and ZTDSR-ZT treatments. Savings of energy in conservation-tillage treatments were attributed to reduced energy use in land preparation (69–100%) and irrigation (23–27%), which consumed a large amount of fuel energy. Conservation-tillage treatments increased grain and straw/stover yields of crops, eventually increased the output energy (6–16%), net energy (14–26%), energy ratio (25–33%), and energy productivity (23–34%) as compared with CTTPR-CT. For these energy parameters, the treatment order was ZTDSR-ZT ≥ ZTTPR-ZT > NPTPR-ZT > CTTPR-CT (p < 0.05). Crop residue retention reduced net energy, energy ratio, and energy productivity when compared with residue removal. Our results of energy-economic relations favored the “conservative hypothesis,” which envisages that energy and monetary investments are not essentially the determinants of crop productivity. Thus, zero tillage-based crop establishments (ZTTPR-ZT, ZTDSR-ZT) in rice-based production systems could be the sustainable alternative to conventional tillage-based agriculture (CTTPR-CT) as they conserved non-renewable energy sources, reduced water requirement, and increased crop productivity.

     

Pollution influences on atmospheric composition and chemistry at high northern latitudes: Boreal and California forest fire emissions

We analyze detailed atmospheric gas/aerosol composition data acquired during the 2008 NASA ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) airborne campaign performed at high northern latitudes in spring (ARCTAS-A) and summer (ARCTAS-B) and in California in summer (ARCTAS-CARB). Biomass burning influences were widespread throughout the ARCTAS campaign. MODIS data from 2000 to 2009 indicated that 2008 had the second largest fire counts over Siberia and a more normal Canadian boreal forest fire season. Near surface arctic air in spring contained strong anthropogenic signatures indicated by high sulfate. In both spring and summer most of the pollution plumes transported to the Arctic region were from Europe and Asia and were present in the mid to upper troposphere and contained a mix of forest fire and urban influences. The gas/aerosol composition of the high latitude troposphere was strongly perturbed at all altitudes in both spring and summer. The reactive nitrogen budget was balanced with PAN as the dominant component. Mean ozone concentrations in the high latitude troposphere were only minimally perturbed (<5 ppb), although many individual pollution plumes sampled in the mid to upper troposphere, and mixed with urban influences, contained elevated ozone (ΔO₃/ΔCO = 0.11 ± 0.09 v/v). Emission and optical characteristics of boreal and California wild fires were quantified and found to be broadly comparable. Greenhouse gas emission estimates derived from ARCTAS-CARB data for the South Coast Air Basin of California show good agreement with state inventories for CO₂ and N₂O but indicate substantially larger emissions of CH₄. Simulations by multiple models of transport and chemistry were found to be broadly consistent with observations with a tendency towards under prediction at high latitudes.     

Biomass burning losses of carbon estimated from ecosystem modeling and satellite data analysis for the Brazilian Amazon region

To produce a new daily record of gross carbon emissions from biomass burning events and post-burning decomposition fluxes in the states of the Brazilian Legal Amazon (Instituto Brasileiro de Geografia e Estatistica (IBGE), 1991. Anuario Estatistico do Brasil, Vol. 51. Rio de Janeiro, Brazil pp. 1–1024). We have used vegetation greenness estimates from satellite images as inputs to a terrestrial ecosystem production model. This carbon allocation model generates new estimates of regional aboveground vegetation biomass at 8-km resolution. The modeled biomass product is then combined for the first time with fire pixel counts from the advanced very high-resolution radiometer (AVHRR) to overlay regional burning activities in the Amazon. Results from our analysis indicate that carbon emission estimates from annual region-wide sources of deforestation and biomass burning in the early 1990s are apparently three to five times higher than reported in previous studies for the Brazilian Legal Amazon (Houghton et al., 2000. Nature 403, 301–304; Fearnside, 1997. Climatic Change 35, 321–360), i.e., studies which implied that the Legal Amazon region tends toward a net-zero annual source of terrestrial carbon. In contrast, our analysis implies that the total source fluxes over the entire Legal Amazon region range from 0.2 to 1.2 Pg C yr⁻¹, depending strongly on annual rainfall patterns. The reasons for our higher burning emission estimates are (1) use of combustion fractions typically measured during Amazon forest burning events for computing carbon losses, (2) more detailed geographic distribution of vegetation biomass and daily fire activity for the region, and (3) inclusion of fire effects in extensive areas of the Legal Amazon covered by open woodland, secondary forests, savanna, and pasture vegetation. The total area of rainforest estimated annually to be deforested did not differ substantially among the previous analyses cited and our own.     

Characterization of aerosols from biomass burning--a case study from Mizoram (Northeast), India

Physical and optical properties of biomass burning aerosols in Northeastern region, India analyzed based on measurements made during February 2002. Large spatial extent of Northeastern Region moist tropical to moist sub-tropical forests in India have high frequency of burning in annual dry seasons. Characterization of resultant trace gases and aerosols from biomass burning is important for the atmospheric radiative process. Aerosol optical depth (AOD) observed to be high during burning period compared to pre- and post-burning days. Peak period of biomass burning is highly correlated with measured AOD and total columnar water vapor. Size distribution of aerosols showed bimodal size distribution during burning day and unimodal size distribution during pre- and post-burning days. Size distribution retrievals from biomass burning aerosols show dominance of accumulation mode particles. Weighted mean radius is high (0.22 microm) during burning period. Columnar content of aerosols observed to be high during burning period in addition to the drastic reduction of visibility. During the burning day Anderson sampler measurements showed dominance of accumulation mode particles. The diurnal averaged values of surface shortwave aerosol radiative forcing af biomass burning aerosols varies from -59 to -87 Wm(-2) on different days. Measured and modeled solar irradiances are also discussed in the paper.     

Cereal waste burning pollution observed in the town of Vitoria (northern Spain)

Agricultural waste burning is a widespread practice throughout the world but there is little information about its pollutant impact. This paper deals with a preliminary study of the pollution observed in Vitoria (Northern Spain) caused by cereal waste burning. The mean hourly flux of pollutants produced by cereal waste burning fires can reach values of 1.4 kt of CO₂, 13 t of TPM and 3 t of NO_x in the area around Vitoria. Measurements obtained in the area of emission and inside fire plumes show high ratios (NO₂/NO_x) indicating that nitrogen oxides emitted by the source undergo a rapid transformation in the same area of emission. Results relating to aerosol composition collected in Vitoria during burning periods show an increase in the concentration of K⁺, NO₃⁻ and Cl⁻ ions, that are inter-correlated. The modification of the ionic composition of aerosols also affects the chemistry of the rain collected in Vitoria. During the burning period, it is particularly noticeable that anthropogenic pollution (usually identifiable by the correlation between SO₄²⁻ and NO₃⁻ concentrations) disappears, indicating the existence of an independent source of NO₃⁻ not linked to the SO₄²⁻ source. Similar results were deduced studying BAPMON data collected in Spain during cereal waste burning. Finally, we note that ozone concentration measured at Vitoria is not affected by the pollution generated by the burning fires.