Agricultural Fires Research Articles

Isotope constraints of the strong influence of biomass burning to climate-forcing Black Carbon aerosols over Southeast Asia

Black Carbon (BC) deteriorates air quality and contributes to climate warming, yet its regionally- and seasonally-varying emission sources are poorly constrained. Here we employ natural abundance radiocarbon (14C) measurements of BC intercepted at a northern Malaysia regional receptor site, Bachok, to quantify the relative biomass vs. fossil source contributions of atmospheric BC, in a first year-round study for SE Asia (December 2015–December 2016). The annual average 14C signature suggests as large contributions from biomass burning as from fossil fuel combustion. This is similar to findings from analogous measurements at S Asian receptors sites (~50% biomass burning), while E Asia sites are dominated by fossil emission (~20% biomass burning). The 14C-based source fingerprinting of BC in the dry spring season in SE Asia signals an even more elevated biomass burning contribution (~70% or even higher), presumably from forest, shrub and agricultural fires. This is consistent with this period showing also elevated ratio of organic carbon to BC (up from ~5 to 30) and estimates of BC emissions from satellite fire data. Hence, the present study emphasizes the importance of mitigating dry season vegetation fires in SE Asia.

Characterizing Weekly Cycles of Particulate Matter in a Coastal Megacity: The Importance of a Seasonal, Size‐Resolved, and Chemically Speciated Analysis

AbstractWe present the first study of the weekly cycles (WCs) of chemically speciated and size‐resolved particulate matter (PM) in Metro Manila, Philippines, a coastal megacity located within a highly complex meteorological environment that is subject to both anthropogenic and natural sources. To measure PM, Micro‐Orifice Uniform Deposit Impactors (MOUDIs) were deployed in Metro Manila from August 2018 to October 2019 and samples were analyzed for ionic and elemental species, including black carbon (BC). The WC in Metro Manila varied remarkably across seasons, linked to shifts in meteorology, transport, and aerosol source. Identified aerosol sources were traffic, local and regional burning, dust, sea salt, and secondary aerosol formation. Direct emissions induced a late workweek peak, while secondary aerosol formation led to a weekend peak in response to precursor buildup mainly from traffic. Seasonal analysis revealed that local burning from solid waste management and agricultural fires induced a strong WC peak while regional burning emissions from the Maritime Continent (MC) and possibly the Asian continent elevated seasonal baseline concentrations of the WC. BC showed a seasonally persistent WC, consistent in magnitude, weekly peak timing, and particle size. The dominant submicrometer WC and the contribution of BC across seasons have important ramifications on public health and policymaking, which are also discussed. As many of the observed WC patterns are undetectable when using only bulk PM, this study demonstrates that a seasonal, size‐resolved, and chemically speciated characterization is required to more fully understand the driving mechanisms governing WCs.

Ландшафтні пожежі в Україні: поточна ситуація та аналіз чинної системи охорони природних територій від пожеж

In the last decade, the problem of fires in the natural landscapes of Ukraine has aggravated due to climate change, changes in society and land use. Catastrophic wildfires in 2014, 2015 and 2020 indicate that Ukraine is now in the new climate conditions in terms of the level of fire danger. It is clear that in such conditions departmental forest and landscapes fire protection system is incapable of control over the situation. Such situation requires an analysis of the effectiveness of the existing forest and landscapes fire protection system and its improvement in accordance with new risks and challenges. Based on the methods of RS with the help of modern software products, it was established that in Ukraine over the past 19 years wildfires have damaged 38.4 million hectares of natural areas, an average of 2.0 million hectares annually. The most severe problem of wildfires is observed in the southern and eastern parts of Ukraine, where forest cover is low, part of agricultural lands is large (over 70%), which indicates, first of all, a problem of agricultural fires. In comparison to fires (burnings) on agricultural lands, the problem of forest fires does not seem very significant. Yet, taking into the account especially large forest fires in Ukraine during 2007 – 2020 that have led to human deaths, destruction of residential buildings, manufacture and social infrastructure, which has resulted in enormous ecological and economical losses, it is clear that forest fire protection system requires deep analysis and appropriate decisions for its improvement. The article is devoted to the study of fires in the natural landscapes of Ukraine, analysis of the current forest and landscapes fire protection system and ways to improve it. The first step towards establishing a modern fire management system in Ukraine should aim at establishing a reliable national fire statistics system, which would highlight the real problem and include all type of landscape fires - in open lands and in forests. The scientific article represents analyzes the landscape fires for the period 2001-2019 according to the global products of the MODIS system. Also in the article, performed the analysis of the components of the current fire management system and the main shortcomings and key recommendations for its improvement are formulated.

Effects of Anthropogenic Chlorine on PM2.5 and Ozone Air Quality in China.

China has large anthropogenic chlorine emissions from agricultural fires, residential biofuel, waste incineration, coal combustion, and industrial processes. Here we quantify the effects of chlorine on fine particulate matter (PM2.5) and ozone air quality across China by using the GEOS-Chem chemical transport model with comprehensive anthropogenic emissions and detailed representation of gas-phase and heterogeneous chlorine chemistry. Comparison of the model to observed ClNO2, HCl, and particulate Cl- concentrations shows that reactive chlorine in China is mainly anthropogenic, unlike in other continental regions where it is mostly of marine origin. The model is successful in reproducing observed concentrations and their distributions, lending confidence in the anthropogenic chlorine emission estimates and the resulting chemistry. We find that anthropogenic chlorine emissions increase total inorganic PM2.5 by as much as 3.2 μg m-3 on an annual mean basis through the formation of ammonium chloride, partly compensated by a decrease of nitrate because ClNO2 formation competes with N2O5 hydrolysis. Annual mean MDA8 surface ozone increases by up to 1.9 ppb, mainly from ClNO2 chemistry, while reactivities of volatile organic compounds increase (by up to 48% for ethane). We find that a sufficient representation of chlorine chemistry in air quality models can be obtained from consideration of HCl/Cl- thermodynamics and ClNO2 chemistry, because other more complicated aspects of chlorine chemistry have a relatively minor effect.

Estimating the air quality and health impacts of biomass burning in northern South America using a chemical transport model

Biomass burning (BB) emissions significantly deteriorate air quality in many regions worldwide, impact human health and perturbing Earth's radiation budget and climate. South America is one of largest contributors to BB emissions globally. After Amazonia, BB emissions from open and agricultural fires of Northern South America (NSA) are the most significant. Recent evidence shows a strong correlation between fire counts in NSA and Brown Carbon in some Colombian cities, suggesting a substantial seasonal contribution of regional BB sources to air pollution levels in the densely populated areas of NSA. In this work we use the atmospheric regional chemical transport model WRF-Chem to assess the contribution of open BB events to pollutant concentration and to estimate potential health impacts associated with wildfire events in NSA. Three nested domains are used to simulate atmospheric composition in the Northern part of South America and the Caribbean. Simulations included biogenic and anthropogenic emissions from a global emission inventory merged with local emissions for the city of Bogotá. Two modelling scenarios were considered, a base case without BB emissions (NO_FIRE) and a sensitivity scenario with BB emissions. Simulations were carried out for periods of strong BB activity in NSA. In the NO_FIRE scenario, aerosol concentrations are unrealistically low. When BB emissions are is included background PM2.5 concentrations increase 80%. The increment in aerosol concentrations is mainly driven by Secondary Organic Aerosols. In the case of Bogotá, the most densely populated city in the domain, monthly mean increase in PM2.5 is 3.3 μg m−3 and 4.3 ppb for O3. Modeled meteorological and air pollution fields are in better agreement with observations when high spatial resolution (3 × 3 km) is used in the simulations. The total estimated short-term all-cause mortality associated to BB during February in the region is 171 cases, 88 PM2.5-related and 83 O3-related mortality.

Downward cloud venting of the central African biomass burning plume during the West Africa summer monsoon

Abstract. Between June and September large amounts of biomass burning aerosol are released into the atmosphere from agricultural fires in central and southern Africa. Recent studies have suggested that this plume is carried westward over the Atlantic Ocean at altitudes between 2 and 4 km and then northward with the monsoon flow at low levels to increase the atmospheric aerosol load over coastal cities in southern West Africa (SWA), thereby exacerbating air pollution problems. However, the processes by which these fire emissions are transported into the planetary boundary layer (PBL) are still unclear. One potential factor is the large-scale subsidence related to the southern branch of the monsoon Hadley cell over the tropical Atlantic. Here we use convection-permitting model simulations with COSMO-ART to investigate for the first time the contribution of downward mixing induced by clouds, a process we refer to as downward cloud venting in contrast to the more common process of upward transport from a polluted PBL. Based on a monthly climatology, model simulations compare satisfactory with wind fields from reanalysis data, cloud observations, and satellite-retrieved carbon monoxide (CO) mixing ratio. For a case study on 2 July 2016, modelled clouds and rainfall show overall good agreement with Spinning Enhanced Visible and InfraRed Imager (SEVIRI) cloud products and Global Precipitation Measurement Integrated Multi-satellitE Retrievals (GPM-IMERG) rainfall estimates. However, there is a tendency for the model to produce too much clouds and rainfall over the Gulf of Guinea. Using the CO dispersion as an indicator for the biomass burning plume, we identify individual mixing events south of the coast of Côte d'Ivoire due to midlevel convective clouds injecting parts of the biomass burning plume into the PBL. Idealized tracer experiments suggest that around 15 % of the CO mass from the 2–4 km layer is mixed below 1 km within 2 d over the Gulf of Guinea and that the magnitude of the cloud venting is modulated by the underlying sea surface temperatures. There is even stronger vertical mixing when the biomass burning plume reaches land due to daytime heating and a deeper PBL. In that case, the long-range-transported biomass burning plume is mixed with local anthropogenic emissions. Future work should provide more robust statistics on the downward cloud venting effect over the Gulf of Guinea and include aspects of aerosol deposition.

Black carbon in spring aerosols of Moscow urban background

Air quality in megacities is recognized as the most important environmental problem. Aerosol pollution by combustion emissions is remaining to be uncertain. Measurements of particulate black carbon (BC) were conducted at the urban background site of Meteorological Observatory (MO) MSU during the spring period of 2017 and 2018. BC mass concentrations ranged from 0.1 to 10 μg m–3, on average 1.5±1.3 and 1.1±0.9 µg/m3 , in 2017 and 2018, respectively. Mean BC concentrations displayed significant diurnal variations with poorly prominent morning peak and minimum at day time. BC mass concentrations are higher at night time due the shallow boundary layer and intensive diesel traffic which results in trapping of pollutants. Wind speed and direction are found to be important meteorological factors affected BC concentrations. BC pollution rose identifies the North as the direction of the preferable pollution. A negative correlation between BC concentrations and wind speed confirms the pollution accumulation preferably in stable weather days. Relation of BC pollution to a number of agriculture fires is distinguishable by air mass transportation from South and South-Est of Russia and Western Europe. Mean season ВС concentrations at rural and remote sites in different world locations are discussed.

Bird Diversity and Community Composition in Kafta Sheraro National Park, Tigray, Northern Ethiopia

Birds are one of the most important components of biodiversity that has huge ecological, economical, and esthetic values. The main objective of this study was to assess diversity and species composition of bird community in Kafta Sheraro National Park, Northern Ethiopia. Data were collected from August 2017 to March 2018 in the national park. Point count method was employed to collect data on bird species diversity and species composition. Direct observations of birds and discussion with local people and scouts to assess potential threats of avifauna in the park were made. Shannon diversity index was used to calculate the species diversity. A total of 158 bird species belonging to 52 different families and 20 orders were identified. Of the recorded species, there were 76.6% residents, 15.8% Palaearctic migrants (PM), 5.7% Intra-African migrants (IM), and 1.9% partial migrants. Accipitiridae (11.4%) had the highest species followed by Columbidae, Estrilidae, and Ploceidae with 7%, 5.7%, and 4.4% species, respectively. The highest Shannon–Weiner diversity index (H′ = 4.50) was recorded during February while the lowest (H′ = 2.18) was recorded during March. Species richness of the park showed no significance difference among the study months (χ2 = 10.046, df = 5, P>0.05). Agricultural expansions, fire, livestock grazing, mining, and poaching were the major threats of the park bird species. Kafta Sheraro National Park is one of the areas with high avian composition in Ethiopia. In the park, wildlife watching in general and ornithological tourism in particular should be developed. Anthropogenic disturbances should also be minimized to conserve avian diversity of the park.

Case Study to Determine the Causes of Fire in Agriculture

Case Study to Determine the Causes of Fire in Agriculture

Land Use and Land Cover Change Within and Around the Greater Serengeti Ecosystem, Tanzania

Land use and land cover (LULC) changes can pose profound impacts on wildlife habitats, abundance and distribution and on human-dominated landscapes. We investigated LULC changes in the Greater Serengeti ecosystem, Tanzania, for a period of 41 years from 1975 to 2015. Specifically, we mapped LULC types for 1975, 1995 and 2015 and assessed the corresponding changes during 1975-1995, 1995-2015 and 1975-2015. We used the random forest classification algorithm to classify Multispectral Scanner (MSS), Thematic Mapper (TM), Enhanced Thematic Mapper Plus (+ETM) and Operational Land Imager (OLI) into eight main classes. We obtained accuracies of 88.4%, 90.6% and 93.4% with Kappa Indices of Agreement (KIA) of 0.86, 0.87 and 0.91 for 1975, 1995 and 2015, respectively. Grassland, shrubland and woodland were the major LULC types throughout 1975-2015 with percentage coverages of 50.6%, 23.7% and 20.9% for 1975; 54.2%, 23.5% and 15.9% for 1995; and 57.0%, 23.8% and 8.9% for 2015, respectively. Overall, woodland cover (-11.1%) was converted to most of the other cover types during 1975-2015. The loss of woodland cover is due to increasing human population size, agriculture, settlements and policy changes fires and elephant browsing. Effective conservation policies and regulation of socio-economic activities in the ecosystem and its buffer area are essential to ameliorate declining vegetation cover, especially along the protected areas boundaries.

Spring Aerosol in Urban Atmosphere of Megacity: Analytical and Statistical Assessment for Source Impacts

In the complex situation with the plurality of emissions, the important research task of assessing the air quality and potential sources through aerosol composition analyses remains for Moscow’s megacity environment. The light absorption, PM10 mass concentration, aerosol composition, and meteorological parameters in this urban background were measured during spring 2017, a period characterized by significant changes in the air temperature, mass advection, and solar radiation. The organic and elemental carbon (OC and EC) and 76 organic compounds, e.g., alkanes, polycyclic aromatic hydrocarbons (PAHs), oxidized PAHs, hopanes, anhydrosugars, polyols, primary and secondary saccharides, and HULIS, as well as 13 ions, including K+, a marker of biomass burning, have been quantified to determine the carbonaceous and inorganic chemical profiles of the aerosol. The correlation between the absorption Ångström exponent (AAE) and the levoglucosan concentration reveals the relative contributions of agricultural fires and residential biomass burning (BB) nearby to the urban aerosol composition. Combining detailed analytical and statistical approaches, we have identified and analyzed the specific chemical compounds that most accurately represent the variability of the aerosol composition. Principal component analysis (PCA) highlights the main factors for marker species related to gasoline/diesel traffic, BB, biogenic activity, and secondary formation in the atmosphere. Distinguishing the BB-affected periods allows us to evaluate daily changes in the aerosol composition in relation to the transported air masses and detected fires in the areas surrounding Moscow.

Analysis of Spatio-Temporal Dynamics of Land Use in the Bouba Ndjidda National Park and Its Adjacent Zone (North Cameroun)

We evaluated the dynamics of land use in the Bouba Ndjidda National Park (BNNP) and adjacent areas, in northern Cameroon. Using a maximum likelihood supervised classification of satellite images from 1990 to 2016, coupled with field and a socio-economic survey, we performed a robust land-use classification. Between 1990 and 2016, the area included eight classes of land use, with the largest in 1990 being the woody savannah (42.9%) followed by the gallery forest (20.2%) and the clear forest (16.3%). Between 1990 and 1999, the gallery forest lost 64.8% of its area mostly to the benefit of woody savannahs. Between 1999 and 2016, the largest loss of area was that of the clear forest, which decreased generally by 43.2% in favor of woody savannah. Rates of increase of crop field areas were 59.6% and 78.8% respectively for the periods of 1990 to 1999 and 1999 to 2016 to the detriment of woody savannahs. We attribute the changes in land use observed mainly to the increasing human population and associated agriculture, overgrazing, fuelwood harvesting and bush fires. The exploitation of non-timber forest products and climatic factors may also have changed the vegetation cover. We recommend the implementation of farming techniques with low impact on the environment such as agroforestry.

Connecting Crop Productivity, Residue Fires, and Air Quality over Northern India

Northwestern India is known as the “breadbasket” of the country producing two-thirds of food grains, with wheat and rice as the principal crops grown under the crop rotation system. Agricultural data from India indicates a 25% increase in the post-monsoon rice crop production in Punjab during 2002–2016. NASA’s A-train satellite sensors detect a consistent increase in the vegetation index (net 21%) and post-harvest agricultural fire activity (net ~60%) leading to nearly 43% increase in aerosol loading over the populous Indo-Gangetic Plain in northern India. The ground-level particulate matter (PM2.5) downwind over New Delhi shows a concurrent uptrend of net 60%. The effectiveness of a robust satellite-based relationship between vegetation index—a proxy for crop amounts, and post-harvest fires—a precursor of extreme air pollution events, has been further demonstrated in predicting the seasonal agricultural burning. An efficient crop residue management system is critically needed towards eliminating open field burning to mitigate episodic hazardous air quality over northern India.

Space and time regularities and development factors of grass fires in the Volga-Urals region

The author generalizes the results of the studies devoted to obtaining reliable information on the long-term dynamics of grass fires in Volga-Urals region and analyzing the data to identify space and time regularities of their development. The results indicate a widespread and considerable extension of an area of fire propagation and frequency starting from the middle of the 1990th - the beginning of the 2000th. The primary precondition for activation of fires in steppe regions is a sharp reduction of agricultural production accompanied by a decrease in pasture load and formation of fallow lands. The modern stage of fire development is characterized by the increased impact of the weather and climate factor. The primary reasons for steppe fires is an ongoing practice of agricultural uncontrolled fires and careless handling of fire. The fire impact brings steppe ecosystems in the condition of long-term stress and has a negative nature as a whole. The conducted studies allowed obtaining actual data on the dynamics of grass fires, revealing seasonal distinctions and peculiar features of development in different natural zones, as well as evaluating the factors of their occurrence and spread. The results indicate a necessity of optimizing the steppe management of natural resources.

Agricultural Fires and Health at Birth

AbstractFire has long served as a tool in agriculture, but the practice's link with economic activity has made its health consequences difficult to study. Drawing on data from satellite-based fire detection systems, air monitors, and vital records in Brazil, we study how in utero exposure to smoke from sugarcane harvest fires affects health at birth. Exploiting daily changes in fire location and wind direction for identification, we find that late-pregnancy smoke exposure decreases birthweight, gestational length, and in utero survival. Fires less associated with smoke exposure predict improved health, highlighting the importance of disentangling pollution from its economic correlates.

The short-term associations of particular matters on non-accidental mortality and causes of death in Chiang Mai, Thailand: a time series analysis study between 2016-2018

ABSTRACT Open burnings, agricultural and forest fires, are the major sources of particulate matters (PM) in Chiang Mai during dry season. We aim to determine the association of an increased daily PM (PM10, PM2.5) and daily non-accidental mortality and causes of death in Chiang Mai. The association between PM and daily non-accidental mortality including causes of death were analyzed using a generalized linear model with Poisson distribution. The results showed that PM10 and PM2.5 were associated with daily non-accidental mortality on different lag days (adjusted RR range from 1.009–1.018 and 1.016 for each 10 µg/m3 increment of PM10 and PM2.5, respectively). The causes of death associated with PM10, PM2.5 found on different lag days were chronic obstructive pulmonary disease (COPD), coronary artery disease (CAD), and sepsis. We concluded that PM10 and PM2.5 are associated with daily non-accidental mortality and causes of death were COPD, CAD, and sepsis.

Extreme smoke event over the high Arctic

The intense western Canadian fires of August 2017 resulted in a (10-year) extreme, high-Arctic smoke event. The primary measurements employed to monitor smoke events were fine mode (FM) aerosol optical depths (AODs) derived from the measured AOD spectra of two AEROCAN/AERONET (CIMEL) sunphotometers at Eureka, Nunavut, Canada. The FM AOD attribution is argued to be a necessary condition for the presence of smoke. Various supporting information, including the correlation with smoke proxy (CO) retrievals, the high frequency (rapid diurnal variation) and the high amplitude nature of the FM AODs, ground-based backscatter lidar profiles, the redundancy of the double CIMEL retrievals, satellite remote sensing, aerosol modeling and backtrajectories indicated that the peak event was likely due to smoke from extreme pyroCb fires in British Columbia.The hypothesis that the FM AOD peak event was an extreme event was tested for a derived ensemble of fine mode events and their peaks over the 10-year sampling period. The results confirmed the hypothesis at the 0.001 level of significance. Important indicators that the 10-year ensemble of FM AOD events did indeed represent smoke were their high frequency and high amplitude FM nature, their occurrence during the Boreal forest fire and agricultural fire seasons in Canada and Asia, and their strong correlation with CO abundances retrieved from FTIR measurements (when sufficient FM AOD and CO statistics were available).In the process of accumulating climatological-scale, monthly-binned fine mode AOD statistics, we found moderate correlations with forest fire or agricultural fire emissions from the Boreal North American, Boreal Asia or Central Asia regions as well as with CO retrievals at Eureka. We argued that confounding factors constraining the monthly binned fine mode AOD vs emissions correlations were associated with the monthly-binned meteorological dynamics (with notable, event-level, exceptions) while confounding factors constraining fine mode AOD vs CO correlations included the different physio-optical nature of those smoke proxies (solar attenuation by fine mode particle scattering versus solar attenuation by molecular absorption). We also employed historic (2005-2010) AHSRL (Arctic High Spectral Resolution Lidar) profiles to estimate an optically averaged smoke plume height of ~3 to 3 ½ km during the spring and summer seasons.

Smoke emissions from agricultural fires in Mexico and Central America

Agricultural burning in Mexico and Central America is a common practice to remove crop residues. Characterization of the spatial and temporal distribution of burning emissions is essential to evaluate their environmental impacts. For this reason, smoke emissions from agricultural fires were calculated using two methods: direct and indirect. The direct method calculates the rate of smoke emission by multiplying the smoke emission coefficient by the fire radiative energy (FRE) release rate. The smoke emission coefficient was calculated from satellite measurements of aerosol optical depth and FRE made by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. The indirect method calculates the rate of smoke emissions by using FRE observations from MODIS to parameterize a diurnal fire cycle based on a Gaussian equation for each ecoregion. Fire emission estimates from each of these methods were compared with each other and with the Global Fire Emissions Database, version 4.1. A total of 482,506 and 233,660 fire pixels were detected by MODIS from 2003 to 2014 in Mexico and Central America, respectively. Active fires concentrate in the tropical forests with maximum frequencies from March to May. Agricultural fires account for 40% of total detected burns from 2003 to 2014. Considerable interannual variability is observed, with 2003, 2005, and 2011 the most active years and 2008 and 2014 the least active years. Our calculations show that agricultural smoke emissions estimated by the indirect method are lower than those estimated by the direct method by a factor of 1.4 to 4, depending on the ecoregion, although the total smoke emissions are similar between both methods. Finally, average annual smoke emissions in Mexico are the greatest in tropical humid forests and least in tropical dry forests, whereas in Central America, average annual smoke emissions are very similar for both humid and dry tropical forests.

The characteristics and local-regional contributions of atmospheric black carbon over urban and suburban locations in Shanghai, China

Black carbon (BC), produced from the incomplete combustion of carbonaceous fuels, has emerged as a major contributor to global climate change with adverse health effects. Based on one-year (2016.06.01–2017.06.30) equivalent black carbon (eBC) measurements, this study analyzed the characteristics of eBC concentrations and the local-regional contributions at an urban site (Pudong, PD) and a suburban site (Qingpu, QP) in Shanghai, China. The results showed that the annual average eBC concentrations were 1.17 ± 0.61 μg m−3 and 2.09 ± 0.97 μg m−3 at PD and QP, respectively. The high eBC concentrations occurred in winter and at weekends both for PD and QP. There were significant negative correlation coefficients between the daily eBC, the daily wind speed (WS) and the daily boundary layer height (BLH) at PD (rws: 0.45, rblh = −0.35, p < 0.01) and QP (rws: 0.49, rblh = −0.32, p < 0.01). And the relative higher eBC concentrations coincided with southerly, southwesterly and westerly winds although these winds had lower frequencies. This could be related to the agricultural fire in these directions during summer harvesttime. The significant partial correlation coefficients of eBC-CO (ru:0.37–0.64, rs:0.18–0.44, p < 0.01) and eBC-NO2 (ru:0.49–0.74, rs:0.38–0.75, p < 0.01) could suggest that eBC mainly come from vehicular exhaust emissions in Shanghai. Besides, the higher eBC/PM2.5 (5.29% ± 1.94%) and eBC/CO(0.30% ± 0.14%) at QP indicated the more combustion activities and diesel-powered vehicle emissions in suburban areas. The concentration weighted trajectory (CWT) analysis indicated that the surrounding areas at the junction of Shanghai, Jiangsu, and Zhejiang provinces seemed to be relatively the most important sources outside of Shanghai.

Amazonian farmers' response to fire policies and climate change

Fires are a major threat to the conservation of the Amazon forest. Despite a large decline in deforestation in the Brazilian Amazon between 2004 and 2012, frequency and extent of forest fires have been increasing over the last two decades. Fires cause huge carbon emissions, biodiversity losses and local economic costs. Fires are anthropogenic and mostly due to the accidental spread of agricultural fires. Yet, there is little data and knowledge about fire mitigation policies' effectiveness. We experimentally assess the impact of two policies under varying drought risk scenarios among Brazilian smallholders. Command and control is more effective than payments for environmental services. We conjecture that the first policy operates through participants' risk aversion (to the fine) and local demand for justice, while payments seem to switch farmers' motivation from normative to monetary payoffs. We also find evidence of a human-mediated, self-reinforcing loop of droughts and fires: droughts increase the exogenous component of fire risk, reducing farmers' incentives to control own fires and to invest in fire-free techniques.