Open Biomass Burning Research Articles

Hourly emissions of air pollutants and greenhouse gases from open biomass burning in China during 2016–2020

Open biomass burning (OBB) is a significant source of air pollutants and greenhouse gases that have contributed to air pollution episodes in China in recent years. An accurate emission inventory is critical for the precise control of OBB. Existing OBB emission datasets are commonly based on MODIS observations, and most only have a daily-scale temporal resolution. Daily OBB emissions, however, might not accurately represent diurnal variations, peak hours, or any open burning processes. The China Hourly Open Biomass Burning Emissions (CHOBE) dataset for mainland China from 2016 to 2020 was developed in this study using the spatiotemporal fusion of multiple active fires from MODIS, VIIRS S-NPP and Himawari-8 AHI detections. At a spatial resolution of 2 km, CHOBE provided gridded CO, NOx, SO2, NH3, VOCs, PM2.5, CO2, CH4 and N2O emissions from OBB. CHOBE will enhance insight into OBB spatiotemporal variability, improves air quality and climate modelling and forecasting, and aids in the formulation of precise OBB preventive and control measures.

Characteristics of atmospheric black carbon and its wet scavenging in Nanning, South China

Based on in-situ measurement of black carbon (BC) and carbon monoxide (CO), the characteristics of BC emissions and wet scavenging were comprehensively investigated in Nanning, South China. The average annual BC concentration was 1.02 ± 0.53 μg m−3 with higher pollution levels during winter. In winter, a higher net BC/CO (ΔBC/ΔCO) ratio of 3.3 ± 0.3 ng m−3 ppb−1 along with an increased absorption Ångström exponent (AAE) and BC mass from biomass burning (BCbb), indicated a significant contribution of biomass burning to BC emissions. However, emissions from the traffic sector consistently exerted a dominant influence throughout the year. Cluster analysis of backward trajectories identified three types of air masses with distinct origins. Cluster #1 originated from Guangxi province and its vicinity, intermittently influencing the sampling site throughout the year with varying effects between winter and summer. This air mass brought in clean sea breeze in summer whereas transported a higher proportion of BCbb to the site during wintertime due to local open biomass burning. Cluster #3 primarily arrived in autumn and winter (October–December) from polluted central China, resulting in substantially high BC mass at the site. Cluster #2 coincided with the period (January–March) when extensive surface open biomass burning events occurred in Southeast Asia (SEA) regions. These BC aerosols in cluster#2 initially rose to higher altitudes above SEA before being regionally transported, but were significantly scavenged by clouds and precipitation during vertical uplift. The remaining BC exhibited a notably lower BC loss rate on relative humidity (RH) of −0.01 ng m−3 ppb−1 %−1 compared to cluster #1 (−0.03) and cluster #3 (−0.06), corresponding to an average BC transport efficiency of 0.85, 0.73, and 0.53, respectively. Nonetheless, air masses in cluster #2 could still transport considerably high BC mass to Nanning due to dry conditions and less wet scavenging along trajectory pathways. These findings provide valuable insights for policymakers and government officials in regulating and mitigating BC pollution in South China.

Enhanced open biomass burning detection: The BranTNet approach using UAV aerial imagery and deep learning for environmental protection and health preservation

Open biomass burning (OBB) in agriculture presents a significant and well-documented challenge, posing severe consequences for both environmental and human health. OBB releases air pollutants that degrade air quality and contribute to climate change, leading to premature deaths in regions with high concentrations of open crop straw burning (OCSB) emissions. Although policies aimed at prohibiting OBB are in place, the efficacy of these regulations in mitigating OCSB emissions remains ambiguous. Consequently, early prevention and monitoring of open biomass combustion are imperative for environmental preservation. Traditional monitoring techniques, reliant on fixed-position cameras, are constrained by their location and monitoring intensity, making concealed fire recognition a complex problem. To address this limitation and monitor the human living environment more flexibly and accurately, we propose a new method to identify straw fires in UAV Aerial Image Using CNN Branch Reinforce Transformer which named BranTNet, enabling early detection and rapid response to crop straw fires. By integrating computer vision technology and deep learning algorithms, straw fires in UAV-acquired aerial survey images can be detected and categorized. In the realm of artificial intelligence algorithms, we skillfully merge convolution and attention mechanisms, harnessing the full potential of both methodologies. Moreover, we seamlessly incorporate transfer learning, skillfully unifying self-training convolution modules with pre-trained transformer modules. This strategic amalgamation not only minimizes time costs but also ensures optimal experimental outcomes. Regarding data, we meticulously collected a substantial number of authentic samples, ensuring the sufficiency of our experimental dataset. The experimental results demonstrate that our proposed method exhibits exceptional accuracy and robustness in detecting and identifying straw fires in UAV aerial survey images. Our approach outperforms the use of convolution or attention mechanisms alone. By integrating this approach with drone technology, we unlock the potential for developing more versatile and precise monitoring solutions, expanding the application of drones to diverse domains. This progress contributes significantly to the early detection and prevention of crop straw fires, fundamentally reducing environmental pollution, curbing carbon emissions, and advancing the cause of carbon neutrality. This innovative technique for monitoring and preventing OBB holds substantial promise in mitigating the adverse effects of OBB on the environment and human health.

Improved biomass burning pollution in Beijing from 2011 to 2018

The prohibition of open straw burning and clean energy transitions, implemented in the last 10 years, resulted in remarkable reductions in ambient biomass burning pollution in Beijing. Here, we present the reduction of biomass burning molecular tracer (i.e., levoglucosan) concentrations using year-long filter sample results collected in Beijing respectively during 2010–2011 and 2017–2018. The annual mean concentrations (95% CI) of levoglucosan during 2010–2011 and 2017–2018 were 0.34 (0.29–0.38) μg m−3 and 0.11 (0.09–0.13) μg m−3, respectively, with a 67% decrease. Compared to 2011, the two traditional open biomass burning episodes in early summer and during the fall post-harvest season disappeared in 2018. Meanwhile, the intensity and duration of biomass burning episodes during the heating season in 2017–2018 was much weaker and shorter than that in 2010–2011. Our results indicate that the implemented clean air action plans were effective in reducing open biomass burning, but the control of biofuel combustion activities during the heating season remains a major challenge in China.

High-resolution atmospheric mercury emission from open biomass burning in China: Integration of localized emission factors and multi-source finer resolution remote sensing data

Mercury (Hg) emissions from open biomass burning represent one of the largest Hg inputs to the atmosphere, with considerable effects on the atmospheric Hg budget. However, there is currently large uncertainty in the inventory of Hg emissions from open biomass burning in China due to limitations on the coarse resolution of burned area products, rough biomass data, and the unavailability of suitable emission factors (EFs). In this study, we developed high tempo-spatial resolution (30 m) and long time-series (2000–2019) atmospheric Hg emission inventories from open biomass burning using the Global Annual Burned Area Map (GABAM) product, high-resolution biomass map, Landsat-based tree cover datasets as well as local EFs in China. The results showed that the average annual Hg emission from open biomass burning in China amounted to 172.6 kg during 2000–2019, with a range of 63–398.5 kg. The largest Hg emissions were found in cropland (72%), followed by forest (25.9%), and grassland (2.1%). On a regional level, Northeast China (NE) and Southwest China (SW) were the two main contributors, together accounting for more than 60% of total Hg emissions. The temporal distribution of Hg emissions showed that the peaks occurred in 2003 and 2014. This is a comprehensive estimation of Hg emissions from open biomass burning in China by integrating various high-resolution remotely sensed data and nationwide localized EFs, which has important implications for understanding the role of open biomass burning in China in regional and global atmospheric Hg budget.

Source apportionment of PM2.5 in Thailand's deep south by principal component analysis and impact of transboundary haze.

Atmospheric particulate matter smaller than 2.5 micron (PM2.5) was evaluated at four sites in the lower southern part of Thailand during 2019-2020 to understand the impact of PM2.5 transport from peatland fires in Indonesia on air quality during the southwest monsoon season. Mass concentration and chemical bound-PM, including carbon composition, e.g., organic carbon (OC) and elemental carbon (EC), polycyclic aromatic hydrocarbons (PAHs), and inorganic elements, were analyzed. The PM2.5 emission sources were identified by principal components analysis (PCA). The average mass concentrations of PM2.5 in the normal period, which represents clean background air, from four sites was 3.5-5.1µg/m3, whereas during the haze period, it rose to 5.4-13.5µg/m3. During the haze period, both OC and EC were 3.5 times as high as in the normal period. The average total PAHs and BaP-TEQ of PM2.5 during the haze period were ~ 1.3-1.7 and ~ 1.2-1.9 times higher than those in the normal period. The K concentrations significantly increased during haze periods. SO42- dominated throughout the year. The effects of external sources, especially the transboundary haze from peatland fires, were significantly enhanced, because the background air in the study locations was generally clean. PCA indicated that vehicle emission, local biomass burning, and secondary particles played a key role during normal period, whereas open biomass burning dominated during the haze phenomena. This was consistent with the OC/EC and PAH diagnostic ratios. Backward trajectories confirmed that the sources of PM during the haze period were predominantly peatland fires in Sumatra, Indonesia, due to southwest wind.

The evolution of open biomass burning during summer crop harvest in the North China Plain

Open biomass burning (OBB) negatively impacts air quality by discharging abundant fine particulate matter (PM2.5, aerodynamic diameter ≤2.5 µm) and trace gases. The statistical methods and numerical simulations have been used to estimate emissions from OBB. The former is poor in producing reliable distributions and transport of emissions, while studies with the latter have focused on cases analysis over short periods. This study investigates the multi-year evaluation of OBB and its contribution to PM2.5 and black carbon (BC) based on satellite observations and numerical modeling over the North China Plain. The number of fires increased by 206% from 2008 to 2012, and decreased by 84% from 2012 to 2016, indicating that the implementation of straw burning ban policy had achieved significant positive effects. The simulation from Weather Research and Forecasting model coupled with chemistry showed that the surface concentrations of PM2.5 and BC emitted by OBB in the burning source area increased from 22 and 3.22 μg/m3, respectively, in 2008 to 45.77 and 6.47 μg/m3, respectively, in 2012, and then decreased to 1.41 and 0.22 μg/m3, respectively, in 2016. The differentiated impacts on air quality of policies across provinces are also investigated. Open crop straw burning was banned early in Shandong and Henan provinces, but they suffer from poor air quality due to open straw burning until the effective straw burning ban in Anhui and Jiangsu provinces, which suggests the need for interregional collaboration for pollution control.

A study of the effect of open biomass burning aerosol on rainfall event over Malaysia by using EOF analysis

Significant biomass burning aerosols resulted from biomass burning activities from Sumatra and Kalimantan Island transported to Malaysia every year from August to October by the southeast monsoon. These transboundary haze changes the precipitation pattern by aerosol interaction with radiation and cloud which affects the solar radiation budget and cloud condensation nuclei properties. In this work, empirical orthogonal function (EOF) was used to assess the effect of biomass burning aerosol on rainfall pattern over Malaysia from both a spatial and a temporal perspective. Over Peninsular Malaysia, regional rainfall activities tend to be suppressed by concentrated biomass burning aerosols and produce another heavy rain over the downwind areas after 30-60 days (60 days) under highly (less) populated condition. Similar precipitation pattern has been indicated over Sarawak and Sabah where biomass burning aerosols suppress rainfall in the southwestern area while leads to a more intensified rainfall event in the northeast area with 30-60 days (60 days) interval under highly (less) populated condition.

Short-term effects of biomass open burning related air pollution on outpatient department visits for cardiovascular and respiratory diseases in Thailand

Short-term effects of biomass open burning related air pollution on outpatient department visits for cardiovascular and respiratory diseases in Thailand

The Effects of Trash, Residential Biofuel, and Open Biomass Burning Emissions on Local and Transported PM2.5 and Its Attributed Mortality in Africa.

Long-term exposure to ambient fine particulate matter (PM2.5) is the second leading risk factor of premature death in Sub-Saharan Africa. We use GEOS-Chem to quantify the effects of (a) trash burning, (b) residential solid-fuel burning, and (c) open biomass burning (BB) (i.e., landscape fires) on ambient PM2.5 and PM2.5-attributable mortality in Africa. Using a series of sensitivity simulations, we excluded each of the three combustion sources in each of five African regions. We estimate that in 2017 emissions from these three combustion sources within Africa increased global ambient PM2.5 by 2%, leading to 203,000 (95% confidence interval: 133,000-259,000) premature mortalities yr-1 globally and 167,000 premature mortalities yr-1 in Africa. BB contributes more ambient PM2.5-related premature mortalities per year (63%) than residential solid-fuel burning (29%) and trash burning (8%). Open BB in Central Africa leads to the largest number of PM2.5-attributed mortalities inside the region, while trash burning in North Africa and residential solid-fuel burning in West Africa contribute the most regional mortalities for each source. Overall, Africa has a unique ambient air pollution profile because natural sources, such as windblown dust and BB, contribute strongly to ambient PM2.5 levels and PM2.5-related mortality. Air pollution policies may need to focus on taking preventative measures to avoid exposure to ambient PM2.5 from these less-controllable sources.

Mapping the Contribution of Biomass Burning to Persistent Organic Pollutants in the Air of the Indo-China Peninsula Based on a Passive Air Monitoring Network.

Biomass burning (BB) is an important source of atmospheric persistent organic pollutants (POPs) across the world. However, there are few field-based regional studies regarding the POPs released from BB. Due to the current limitations of emission factors and satellites, the contribution of BB to airborne POPs is still not well understood. In this study, with the simultaneous monitoring of BB biomarkers and POPs based on polyurethane foam-based passive air sampling technique, we mapped the contribution of BB to polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in the Indo-China Peninsula. Spearman correlations between levoglucosan and 16 PCBs (rs = 0.264-0.767, p < 0.05) and 2 OCPs (rs = 0.250-0.328, p < 0.05) confirmed that BB may facilitate POP emissions. Source apportionment indicated that BB contributed 9.3% to the total PCB and OCP mass. The high contribution of positive matrix factorization-resolved BB to PCBs and OCPs was almost consistent with their concentration distributions in the open BB season but not completely consistent with those in the pre-monsoon and/or monsoon seasons. Their contribution distributions may reflect the use history and geographic distribution in secondary sources of POPs. The field-based contribution dataset of BB to POPs is significant in improving regional BB emission inventories and model prediction.

Enhanced aerosols over the southeastern Tibetan Plateau induced by open biomass burning in spring 2020

The Tibetan Plateau is the third pole of the world, with an essential role in regulating Northern Hemisphere climate. Previous studies showed that atmospheric aerosols over the Tibetan Plateau are influenced by biomass burning (BB) products from South and Southeast Asia. In fact, open biomass burning (OBB) is also an important form of BB in Southeast Asian countries, causing serious springtime air pollution yearly. However, there are still scientific gaps in the contribution of OBB to surrounding regional aerosols, especially on the Tibetan Plateau. In order to quantify this contribution, we collected samples of fine particulate matter and derived the concentrations of major water soluble ion, water soluble organic carbon (WSOC), and total carbon (TC) and total nitrogen (TN) as well as the dual isotopic compositions of carbon and nitrogen (δ13C and δ15N) during March–June on the southeastern Tibetan Plateau. δ13C and δ15N showed no significant difference (p > 0.05) between the OBB and non-OBB periods. Furthermore, both δ13C and δ15N (−25.7 ± 0.7 ‰ and 8.0 ± 3.6 ‰) values calculated during the whole sampling period were similar to the BB value, indicating that the primary source of TC and TN in aerosols was BB, whether OBB or non-OBB burning periods. TC and TN concentrations during the OBB period (6.5 ± 2.9 μg m−3 and 1.2 ± 0.4 μg m−3, respectively) were significantly higher than during the non-OBB period (4.1 ± 1.7 μg m−3, with p = 0.014, and 0.7 ± 0.3 μg m−3, with p = 0.013, respectively). Active fire data and surface smoke concentrations further indicated that BB emissions from Southeast Asia were higher during the OBB period. This suggests that OBB-related high BB emissions significantly enhanced atmospheric aerosols concentrations on the southeastern Tibetan Plateau.

The Effects of Trash, Residential Biofuel, and Open Biomass Burning Emissions on Local and Transported PM2.5 and its Attributed Mortality in Africa

The Effects of Trash, Residential Biofuel, and Open Biomass Burning Emissions on Local and Transported PM2.5 and its Attributed Mortality in Africa

Strategy Design of PM2.5 Controlling for Northern Thailand

The emission of fine particulate matter (PM2.5) in dry season from the open biomass burning has caused a long-term negative impact on residents’ health in Northern Thailand. This study takes Chiang Mai and Chiang Rai provinces in Northern Thailand as the study areas to identify pollution episodes, analyze PM2.5 source trajectories, and finally propose pollution control strategies accordingly. PM2.5 levels during 2019–2021 of three representative air pollution monitoring stations (i.e., Chaing Mai-35T, Chiang Rai-57T, and Mae Sai-73T) in these two provinces were collected and analyzed. The Air Quality Index (AQI) defined by PM2.5 level higher than 91 µg m-3 causing serious adverse health effects was adopted to define periods having pollution levels, and the days of the air pollution episodes were identified. Based on these episodes, we applied the backward trajectory model to identify the sources of pollutants. Results showed that PM2.5 levels were significantly higher between February to April compared with other months during 2019–2021 at all three monitoring stations, indicating the severity of PM2.5 episode during the dry season. The backward trajectory demonstrated that air mass transported through the Northern Thailand or nearby mountain areas (categorized as long- or short-transport-distance) contributed up to 21.6% and 75.9% of the total air mass, respectively. Although residents in these mountainous areas are accustomed to the biomass burning, we suggested that there should be urgent needs for the improvement of the long-term air quality in these two provinces. Therefore, this study proposes some control strategies including improvement of prevention knowledge, increase of the risk perception, cultivation of the protection behavior, and intensification of the social influence. In addition to reducing biomass burning pollution, this improvement plan also has a co-benefit of achieving resources recycling concomitantly. Providing effective management strategies may reduce the adverse health effects to Thai residents.

Evaluation of combustion characteristics in biomass residues open burning

Open burning of biomass residues is known as major source of atmospheric pollutant in agricultural areas. Biomass open burning released several toxic compounds that endanger not only human health but also enhance global warming effect. This paper aims to evaluate the characteristics of combustion in bagasse, rice straw and leaf litter open burning. Experimental furnace is designed to mimic the open burning condition with controlled observation system of combustion parameters i.e., temperature, gas composition, and particulate concentration. It is obtained that bagasse produced the lowest emission factor compared to other biomasses combustion i.e., 35 g CO/kg biomass and 0.2 g PM/kg biomass. High temperature level is obtained to be the main factor of low emission emitted in open burning.

Impact of satellite AOD data on top-down estimation of biomass burning particulate matter emission

Particulate matter emitted from open biomass burning affects climate, air quality and public health. In the development of remote sensing techniques, top-down methods using satellite observations have become an effective way to estimate particulate matter emissions, but different spatial resolution and coverage of satellite aerosol optical depth (AOD) products introduce great uncertainties. In this work, we assess the differences in total particulate matter (TPM) emission when calculated using different satellite AOD data. To do this, we derive top-down biomass burning TPM emission coefficients (Ce) of Australia based on 1 km and 10 km MODIS AOD products, and compare the results of emission estimation. Using high spatial resolution AOD data, a 90 % decrease of Ce mean value is found in Australia, and the quality of Ce improves by 290 %. When we use 1 km AOD data in place of 10 km AOD data, the estimation of biomass burning TPM emissions in Australia during 2012–2020 drops from 1.08Tg to 0.11Tg; the temporal trends of the two products remain the same. The TPM emission estimates for biome based on higher spatial resolution AOD data in this study are lower than Fire Energetics and Emissions Research (FEERv1) inventories by factors of 0.08–0.2. Our work shows that using satellite AOD products of higher spatial resolution avoids overestimation of biomass burning TPM emissions, and improves the quality of final estimates, providing a possible way to understand biomass burning emission more accurately.

Environmental impact assessment of VOC emissions from biomass gasification power generation system based on life cycle analysis

The control of volatile organic compounds (VOC) is one of the key challenges in biomass combustion. This study aims to establish a process-based model to assess the life cycle VOC emissions of a biomass gasification power plant in China. In this study, the life cycle assessment (LCA) method was used for the first time to evaluate the direct VOC emissions and indirect VOC emissions from biomass gasification power generation. The whole system consists of three parts: biomass waste feedstock system, gasification power generation system and waste treating system. And waste treatment mainly includes waste water treatment and waste gas treatment. Results show that the life cycle VOC emissions intensity from the biomass gasification power generation process as a whole are calculated as 57.05 g/MWh, without considering the influence of air pollution control devices’ (APCDs). With the implementation of APCDs, this value will be reduced to 7.08 to 22.83 g/MWh, reducing by 12.41 to 40.02 %. In the scenario analysis, APCDs with different combinations of installations are evaluated by applying the practical engineering applications. The scenario of selective catalytic reduction (SCR) and wet electrostatic precipitation (WESP) can achieve the best removal effect, under which VOC emissions intensity can achieve 34.22 g/MWh, and the indirect emissions account for 46.15 % of life cycle VOC emissions, which are mainly from wastewater treatment process. The photochemical ozone generation potential and ozone layer depletion potential from emitted VOC are the two largest in this scenario, accounting for 17.71 % and 8.59 % respectively. If all open burning and indoor combustion of biomass in China can be replaced by the biomass gasification power generation technology, the relevant national VOC emissions reduction potential could reach up to 1.95 Mt/year. Among all the provinces, Heilongjiang, Anhui, Henan, Shandong and Jilin are the five provinces with the highest VOC emissions reduction potential. The influence of key input variables on overall VOC emission is also analyzed in this study. Based on the results, the optimal direction and possible measures to reduce VOC emission are put forward. This study is of great significance for the accurate control of VOC emissions in biomass gasification power generation technology.

Transboundary haze from peatland fires and local source-derived PM2.5 in Southern Thailand

This study characterizes impacts on PM2.5 of transboundary haze from peatland fires in Indonesia and local emission sources during 2019–2020 to a large and densely populated city, Hat Yai in southern Thailand. Organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC), water soluble ions (WSI: Cl−, NO3−, SO42− and NH4+), element tracers (K, Na, Mg and Ca), heavy metals (Cr, Co, Pb, Cd, Ni, Mn) and As, and 16 polycyclic aromatic hydrocarbon (PAHs) components from PM2.5 samples (n = 18) were measured to identify local and regional emission sources using a chemical mass balance (CMB) model. We used a combination of air mass backward trajectories and CMB source apportionment to identify PM2.5 sources. An increase of PM2.5 and chemical component concentrations, during the transboundary haze period, were clearly influenced by aerosols from open biomass burning in Indonesia: PAH concentrations were 2 times higher and OC concentrations, 5 times higher. Secondary organic carbons were predominant during transboundary haze periods, accounting for 52–58% of total OC, indicating higher secondary organic aerosol formation. High K levels demonstrated that the dominant source during this period was biomass burning. Whereas a high level of Ca in the background air came from urban road dust, as well as local biomass burning. Moreover, the increased concentration of SO42−, NH4+ and NO3− during the wet season, as well as transboundary haze periods, was mainly derived the secondary inorganic aerosol formation. Effect on PM2.5 concentration from a volcanic eruption near the air mass trajectory during the sampling period was minimal. However, it may have contributed slightly to an increase of SO42− concentration in PM2.5. Sources of PM2.5 in Hat Yai were clearly influenced by local emission sources, e.g. diesel combustion and biomass burning (rubber wood and rice straw), transboundary haze and also secondary organic and inorganic aerosols.

Introducing the VIIRS-based Fire Emission Inventory version 0 (VFEIv0)

Abstract. A new open biomass burning inventory is presented that relies on the fire radiative power data from the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi NPP satellite. This VIIRS-based Fire Emission Inventory (VFEI) provides emission data from early 2012 to 2019 for more than 40 species of gases and aerosols at spatial resolutions of around 500 m. We found that VFEI produces similar results when compared to other major inventories in many regions of the world. Additionally, we conducted regional simulations using VFEI with the Weather Research and Forecasting (WRF) model with chemistry (WRF-Chem) for Southern Africa (September 2016) and North America (July–August 2019). We compared aerosol optical depth (AOD) from the model against two observational datasets: the MODIS Multi-Angle Implementation of Atmospheric Correction (MAIAC) product and AErosol RObotic NETwork (AERONET) stations. Results showed good agreement between both simulations and the datasets, with mean AOD biases of around +0.03 for Southern Africa and −0.01 for North America. Both simulations were not only able to reproduce the AOD magnitudes accurately, but also the inter-diurnal variations of smoke concentration. In addition, we made use of the airborne data from the ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES; Southern Africa) and the Fire Influence on Regional to Global Environments Experiment and Air Quality (FIREX-AQ; North America) campaigns to evaluate the simulations. In Southern Africa, results showed correlations higher than 0.77 when comparing carbon monoxide and black carbon. In North America, correlations were lower and biases higher. However, this is because the model was not able to reproduce the timing, shape, and location of individual plumes over complex terrain (Rocky Mountains) during the FIREX-AQ campaign period.

Polybrominated dibenzo-p-dioxins/furans and their chlorinated analogues in sediments from a historical hotspot for both brominated flame retardants and organochlorine pesticides

Polybrominated dibenzo-p-dioxin/furans (PBDD/Fs) and polychlorinated dibenzo-p-dioxin/furans (PCDD/Fs) in the environment are closely related to their precursors, brominated flame retardants (BFRs) and organochlorine pesticides (OCPs). However, their change trends following the regulation of BFRs and OCPs remain incompletely characterized. Here, we examined PBDD/Fs and PCDD/Fs in sediments from a historical hotspot for both BFRs and OCPs, namely the Pearl River Delta (PRD), China. PBDD/Fs showed ubiquity in these samples but significantly lower concentrations than PCDD/Fs. Spatially, the occurrence of PBDD/Fs was positively correlated with local development levels and sediments from highly urbanized/industrialized areas showed higher and increasing PBDD/F concentrations. Polybrominated diphenyl ether (PBDE)-related products/industries were the greatest PBDD/F contributors to the PRD, followed by bromo-phenol/benzene-related products/industries. PCDD/Fs in PRD sediments showed significant positive correlations with local grain planting area, yield, and pesticide consumption. The historical use of pentachlorophenol (PCP)/PCP-Na and biomass open-burning were the leading PCDD/F sources of the PRD agricultural/rural areas, where the concentrations and toxic equivalent quantities (TEQs) of PCDD/Fs in sediments changed very little over the past decade. Anthropogenic thermal processes involved in metallurgy, waste incineration, and vehicles were the greatest PCDD/F contributors in the PRD urban/industrial areas, where the PCDD/F concentrations in sediments almost doubled over the last decade. This finding indicates the increasing PCDD/F contributions of industrial and municipal activities in the PRD, despite the implementation of strict emission standards. Over sixty percent of the samples showed TEQs that surpassed the low-risk threshold specified for mammalian life by the U.S. EPA (2.5 pg TEQ g−1) and warrant continuous attention.