Estimating emissions from crop residue open burning in China based on statistics and MODIS fire products

With the objective of reducing the large uncertainties in the estimations of emissions from crop residue open burning, an improved method for establishing emission inventories of crop residue open burning at a high spatial resolution of 0.25°× 0.25° and a temporal resolution of1 month was established based on the moderate resolution imaging spectroradiometer（MODIS） Thermal Anomalies/Fire Daily Level3 Global Product（MOD/MYD14A1）. Agriculture mechanization ratios and regional crop-specific grain-to-straw ratios were introduced to improve the accuracy of related activity data. Locally observed emission factors were used to calculate the primary pollutant emissions. MODIS satellite data were modified by combining them with county-level agricultural statistical data, which reduced the influence of missing fire counts caused by their small size and cloud cover. The annual emissions of CO2, CO, CH4,nonmethane volatile organic compounds（NMVOCs）, N2O, NOx, NH3, SO2, fine particles（PM2.5）,organic carbon（OC）, and black carbon（BC） were 150.40, 6.70, 0.51, 0.88, 0.01, 0.13, 0.07, 0.43,1.09, 0.34, and 0.06 Tg, respectively, in 2012. Crop residue open burning emissions displayed typical seasonal and spatial variation. The highest emission regions were the Yellow-Huai River and Yangtse-Huai River areas, and the monthly emissions were highest in June（37%）.Uncertainties in the emission estimates, measured as 95% confidence intervals, range from a low of within ±126% for N2O to a high of within ± 169% for NH3.

Primary and secondary organic aerosol in an urban/industrial site: Sources, health implications and the role of plastic enriched waste burning

PM_(1)0 samples were collected from an urban/industrial site nearby Athens,where uncontrolled burning activities occur.PAHs,monocarboxylic,dicarboxylic,hydroxycarboxylic and aromatic acids,tracers from BVOC oxidation,biomass burning tracers and bisphenol A were determined.PAH,monocarboxylic acids,biomass burning tracers and bisphenol A were increased during autumn/winter,while BSOA tracers,dicarboxylic-and hydroxycarboxylic acids during summer.Regarding aromatic acids,different sources and formation mechanisms were indicated as benzoic,phthalic and trimellitic acids were peaked during summer whereas p-toluic,isophthalic and terephthalic were more abundant during autumn/winter.The Benzo[a]pyrene-equivalent carcinogenic power,carcinogenic and mutagenic activities were calculated showing significant(p<0.05)increases during the colder months.Palmitic,succinic and malic acids were the most abundant monocarboxylic,dicarboxylic and hydrocarboxylic acids during the entire sampling period.Isoprene oxidation was the most significant contributor to BSOA as the isoprene-SOA compounds were two times more abundant than the pinene-SOA(13.4±12.3 and 6.1±2.9 ng/m^3,respectively).Ozone has significant impact on the formation of many studied compounds showing significant correlations with:isoprene-SOA(r=0.77),hydrocarboxylic acids(r=0.69),pinene-SOA(r=0.63),dicarboxylic acids(r=0.58),and the sum of phthalic,benzoic and trimellitic acids(r=0.44).PCA demonstrated five factors that could explain sources including plastic enriched waste burning(30.8%),oxidation of unsaturated fatty acids(23.0%),vehicle missions and cooking(9.2%),biomass burning(7.7%)and oxidation of VOCs(5.8%).The results highlight the significant contribution of plastic waste uncontrolled burning to the overall air quality degradation.

Influence of fuel mass load,oxygen supply and burning rate on emission factor and size distribution of carbonaceous particulate matter from indoor corn straw burning

The uncertainty in emission estimation is strongly associated with the variation in emission factor （EF）,which could be influenced by a variety of factors such as fuel properties,stove type,fire management and even methods used in measurements.The impacts of these factors are complicated and often interact with each other.Controlled burning experiments were conducted to investigate the influences of fuel mass load,air supply and burning rate on the emissions and size distributions of carbonaceous particulate matter （PM） from indoor corn straw burning in a cooking stove.The results showed that the EFs of PM （EFPM）,organic carbon （EFOC） and elemental carbon （EFEC） were independent of the fuel mass load.The differences among them under different burning rates or air supply amounts were also found to be insignificant （p 〉 0.05） in the tested circumstances.PM from the indoor corn straw burning was dominated by fine PM with diameter less than 2.1 μm,contributing 86.4%±3.9% of the total.The size distribution of PM was influenced by the burning rate and air supply conditions.On average,EF PM,EF OC and EF EC for corn straw burned in a residential cooking stove were （3.84±1.02）,（0.846±0.895） and （0.391±0.350） g/kg,respectively.EF PM,EF OC and EF EC were found to be positively correlated with each other （p 〈 0.05）,but they were not significantly correlated with the EF of co-emitted CO,suggesting that special attention should be paid to the use of CO as a surrogate for other incomplete combustion pollutants.

Compositional characteristics and toxicological responses of human lung epithelial cells to inhalable particles (PM_(10)) from ten typical biomass fuel combustions

As the primary component of haze,atmospheric inhalable particulate matters(PMio)are highly detri-mental to human health.Biomass combustion is one of China's most pivotal sources to aerosols pollution,inducing non-negligible emissions and uncertain risks.PMio samples directly from 10 representative biomass fuel combustion sources(2 groups covering the reality widely:straws of rice,wheat,corn,corncob,soybean,peanut,rape,sesame;and branches of pine,peach)were collected using the dilution channel sampler and analyzed for chemical compositions and in vitro cytotoxicity to human lung epithelial cell lines A549.The components of PMio are dominated by organic carbon(OC),followed by Water-soluble K+and Cl,and rich in metals Fe,Zn,Cr,and Ni.Generally,PMio emitted from biomass fuel combustions can weaken the antioxidant capacity of cells,and straws emissions,especially rape and peanut straws,show stronger ability to further induce oxidative stress and inflammatory damage than fuelwoods,owing to the key toxic roles of Cr,Ni,and Co.Therefore,reducing the specific source emis--sions of PMio from crop straw combustions rich in heavy metals could be an effective oriented strategy to improve environmental air quality and control aerosols pollution precisely for protecting public health.

Local PM_(10) and PM_(2.5) emission inventories from agricultural tillage and harvest in northeastern China

Mineral particles or particulate matters（PMs） emitted during agricultural activities are major recurring sources of atmospheric aerosol loading.However,precise PM inventory from agricultural tillage and harvest in agricultural regions is challenged by infrequent local emission factor（EF） measurements.To understand PM emissions from these practices in northeastern China,we measured EFs of PM_（10） and PM_（2.5） from three field operations（i.e.,tilling,planting and harvesting） in major crop production（i.e.,corn and soybean）,using portable real-time PM analyzers and weather station data.County-level PM_（10） and PM_（2.5） emissions from agricultural tillage and harvest were estimated,based on local EFs,crop areas and crop calendars.The EFs averaged（107 ± 27）,（17 ± 5） and 26 mg/m^2 for field tilling,planting and harvesting under relatively dry conditions（i.e.,soil moisture 〈15%）,respectively.The EFs of PM from field tillage and planting operations were negatively affected by topsoil moisture.The magnitude of PM_（10） and PM_（2.5） emissions from these three activities were estimated to be 35.1 and 9.8 kilotons/yr in northeastern China,respectively,of which Heilongjiang Province accounted for approximately45%.Spatiotemporal distribution showed that most PM_（10） emission occurred in April,May and October and were concentrated in the central regions of the northeastern plain,which is dominated by dryland crops.Further work is needed to estimate the contribution of agricultural dust emissions to regional air quality in northeastern China.