Emissions Of Hazardous Air Pollutants Research Articles

Geographic information system-based determination of priority monitoring areas for hazardous air pollutants in an industrial city.

Industrial cities are hotspots for many hazardous air pollutants (HAPs), which are detrimental to human health. We devised an identification method to determine priority HAP monitoring areas using a comprehensive approach involving monitoring, modeling, and demographics. The methodology to identify the priority HAP monitoring area consists of two parts: (1) mapping the spatial distribution of selected categories relevant to the target pollutant and (2) integrating the distribution maps of various categories and subsequent scoring. The identification method was applied in Ulsan, the largest industrial city in South Korea, to identify priority HAP monitoring areas. Four categories related to HAPs were used in the method: (1) concentrations of HAPs, (2) amount of HAP emissions, (3) the contribution of industrial activities, and (4) population density in the city. This method can be used to select priority HAP monitoring areas for intensive monitoring campaigns, cohort studies, and epidemiological studies.

Economical Operation and Hazardous Air Pollutant Emissions of Biodegradable Sludge Combustion Process in Commercial Fluidized Bed Plant

Waste sludge is characterized by high moisture, volatile compounds, toxic compounds, and ashes. The efficient operation of a commercial fluidized bed combustion (FBC) plant is important for reducing operational costs. We selected a commercial FBC plant for industrial waste sludge combustion to investigate the mass balance of the FBC process and the performance of the air pollution control device. Based on fuel analysis, the flow rate of incineration air was calculated as 4567 Nm3/h. After FBC combustion, the flow rate of the incineration gas increased to 8493.8 Nm3/h. Analysis of the heat balance showed that some heat potential was lost through leakage during the combustion process. The temperature of the incineration gas decreased to 200 °C at the inlet of the air pollution control device. According to the hazardous air pollutant emission testing of sampling points, the operation factors of lime slurry injection for SOx and HCl in the semi-dry reactor were 64.20 and 4.81 kg/h, respectively. In the wet scrubber, the operation factors of NaOH for SOx and HCl were 23.88 and 3.14 kg/h, respectively. At these operation factors, the available waste generation in the semi-dry reactor and wet scrubber was optimized to 76.6 and 42.57 kg/h, respectively.

Spatiotemporally resolved emissions and concentrations of styrene, benzene, toluene, ethylbenzene, and xylenes (SBTEX) in the US Gulf region

Abstract. Styrene, benzene, toluene, ethylbenzene, and xylenes (SBTEX) are established neurotoxicants. SBTEX contains hazardous air pollutants (HAPs) that are released from the petrochemical industry, combustion process, transport emission, and solvent usage sources. Although several SBTEX toxic assessment studies have been conducted, they have mainly relied on ambient measurements to estimate exposure and limit their scope to specific locations and observational periods. To overcome these spatiotemporal limitations, an air quality modeling system over the US Gulf region was created, predicting the spatially and temporally enhanced SBTEX modeling concentrations from May to September 2012. Due to the incompleteness of SBTEX in the official US Environmental Protection Agency (EPA) National Emission Inventory (NEI), the Hazardous Air Pollutions Imputation (HAPI) program was used to identify and estimate the missing HAP emissions. The improved emission data were processed to generate the chemically speciated hourly gridded emission inputs for the Comprehensive Air Quality Model with Extensions (CAMx) chemical transport model to simulate the SBTEX concentrations over the Gulf modeling region. SBTEX pollutants were modeled using the Reactive Tracer feature in CAMx that accounts for their chemical and physical processes in the atmosphere. The data show that the major SBTEX emissions in this region are contributed by mobile emissions (45 %), wildfire (30 %), and industry (26 %). Most SBTEX emissions are emitted during daytime hours (local time 14:00–17:00), and the emission rate in the model domain is about 20–40 t h−1, which is about 4 times higher than that in the nighttime (local time 24:00–04:00, about 4–10 t h−1). High concentrations of SBTEX (above 1 ppb) occurred near the cities close to the I-10 interstate highway (Houston, Beaumont, Lake Charles, Lafayette, Baton Rouge, New Orleans, and Mobile) and other metropolitan cities (Shreveport and Dallas). High styrene concentrations were co-located with industrial sources, which contribute the most to the styrene emissions. The HAPI program successfully estimated missing emissions of styrene from the chemical industry. The change increased total styrene emissions by 22 %, resulting in maximum ambient concentrations increasing from 0.035 to 1.75 ppb across the model domain. The predicted SBTEX concentrations with imputed emissions present good agreement with observational data, with a correlation coefficient (R) of 0.75 (0.46 to 0.77 for individual SBTEX species) and a normalized mean bias (NMB) of −5.6 % (−24.9 % to 32.1 % for the individual SBTEX species), suggesting their value for supporting any SBTEX-related human health studies in the Gulf region. The SBTEX data were published at Zenodo (https://doi.org/10.5281/zenodo.7967541) (Wang et al., 2023), and the HAPI tool was also published at Zenodo (https://doi.org/10.5281/zenodo.7987106) (Wang and Baek, 2023).

Effect of the Method Detection Limit on the Health Risk Assessment of Ambient Hazardous Air Pollutants in an Urban Industrial Complex Area

Hazardous air pollutants (HAPs) significantly impacted environmental air quality and were widely studied to determine human health risks. Kaohsiung is Taiwan’s second-largest city, known for its heavily industrialized and densely populated development. The Linhai industrial park, located in this region, contains roughly 500 industrial facilities that contributed to the emission of HAPs. The purpose of this study was to identify the volatile organic compound (VOCs) and particulate matter (PM)-bounded heavy metals and to examine the effects of the method detection limit (MDL) for analyzed species and the sampling program on health risk assessments. This study identified formaldehyde, 1,2-dichloroethane, acetaldehyde, benzene, and vinyl chloride. As, ethylbenzene, Ni, Cr(VI), Cd, Pb, and 1,3-butadiene were defined as high-risk species and VOCs accounted for more than 95% of respiratory-related health risks, this study proposes that the MDL for analysis methods and the sampling frequency for different species (and the species of interest) would eventually affect the results of health risk assessments. In other words, the current control strategies for reducing health risks may be ineffective. This research output can be used to comprehend the effects of MDL on the health risk assessments of HAPs better while also providing a reliable method to determine the major sources of air pollutants in urban industrial areas.

Hazardous air pollutant emissions estimates from wildfires in the wildland urban interface.

Fires that occur in the wildland urban interface (WUI) often burn structures, vehicles, and their contents in addition to biomass in the natural landscape. Because these fires burn near population centers, their emissions may have a sizeable impact on public health, necessitating a better understanding of criteria and hazardous air pollutants emitted from these fires and how they differ from wildland fires. Previous studies on the toxicity of emissions from the combustion of building materials and vehicles have shown that urban fires may emit numerous toxic species such as hydrogen cyanide, hydrogen fluoride, hydrogen chloride, isocyanates, polycyclic aromatic hydrocarbons (PAHs), dioxins and furans, and a range of toxic organic compounds (e.g. benzene toluene, xylenes, styrene, and formaldehyde) and metals (e.g. lead, chromium, cadmium, and arsenic). We surveyed the literature to create a compendium of emission factors for species emitted from the combustion of building and vehicle materials and compared them with those from wildland fires. Emission factors for some toxic species like PAH and some organic compounds were several orders of magnitude greater than those from wildfires. We used this emission factor compendium to calculate a bounding estimate of the emissions from several notable WUI fires in the western United States to show that urban fuels may contribute a sizeable portion of the toxic emissions into the atmosphere. However, large gaps remain in our understanding of the fuel composition, fuel consumption, and combustion conditions in WUI fires that constrain our ability to estimate the impact of WUI fires.

Heterogeneous Variations on Historical and Future Trends of CO2 and Multiple Air Pollutants from the Cement Production Process in China: Emission Inventory, Spatial-Temporal Characteristics, and Scenario Projections.

Cement production is a major contributor to carbon dioxide (CO2) and multiple hazardous air pollutant (HAP) emissions, threatening climate mitigation and urban/regional air quality improvement. In this study, we established a comprehensive emission inventory by coupling the unit-based bottom-up and mass balance methods, revealing that emissions of most HAPs have been remarkably controlled. However, an increasing 6.0% of atmospheric mercury emissions, as well as 14.1 and 23.7% of fuel-related and process-related CO2 emission growth were witnessed unexpectedly. Industrial adjustment policies have imposed a great impact on the spatiotemporal changes in emission characteristics. Monthly emissions of CO2 and multiple HAPs decreased from December to February due to the "staggered peak production," especially in northern China after implementing the intensified action plan for air pollution control in winter. Upgrading environmental technologies and adjusting capacity structures are identified as dominant driving forces for reducing HAP emissions. Besides, energy intensity improvement can help offset some of the impact caused by the increase in clinker/cement production. Furthermore, scenario analysis results show that ultra-low emission and low-carbon technology transformation constitute the keys to achieve the synergic reduction of CO2 and multiple HAP emissions in the future.

Air pollutant emissions from sludge-bituminous briquettes as a potential household energy source

To promote the sustainable and clean use of sewage sludge (SS) and bituminous coal (BC), BC was mixed with SS at 2%, 4% and 16% as sludge-coal briquettes (named by SBC1, SBC2 and SBC3) which were characterized in this study to evaluate combustion performance and emissions of hazardous air pollutants in an advanced residential stove. Fuel burning rate and modified combustion efficiency (MCE) were similar among the three fuels, while the emission factors of carbon monoxide (CO) and mercury (Hg) were significantly different ( p < 0.05), with the highest emissions from the biomass-coal briquette with the sludge content of 4%. Ash content is a key factor affecting the emission factors (EFs) of CO and Hg. EFs of particulate matter with aerodynamic equivalent diameter ≤2.5 μm (PM 2.5 ) was significantly correlated with the EFs of nitrogen oxides (NO x ), cadmium (Cd) and total polycyclic aromatic hydrocarbons (tPAHs). It appears that by mixing sludge with briquettes at 16%, there were insignificant changes in emissions of most hazardous pollutants including Hg and PAHs compared with mixing sludge at 2%. This study suggested possibilities in support of high-efficient co-utilization of sludge and briquette coals especially in the residential sector.

A comprehensive emission inventory of hazardous air pollutants from municipal solid waste incineration in China

The Hazardous air pollutants (HAPs) released from increasing municipal solid waste incineration (MSWI) plants have drawn great concerns in China. However, a full picture of their emission characteristics is still urgently needed, especially after the implementation of stricter emission limits on MSWI. In this study, a comprehensive historical emission inventory of HAPs emitted from MSWI plants in China during the period of 2006–2017 was dedicatedly established by integrating with detailed plant-level activity data and renewed localized emission factors. Overall, HAPs emissions initially increased with years, then peaked or slowed increase in the year 2014, but leveled off after 2016 due to the gradually and fully implementing of newly revised national emission standard (GB18485–2014) applied to mainland China and much stricter local standards for several provinces and cities. It was estimated that totally 50,716 tons (t) of NOx, 13,026 t of CO, 7988 t of SO2, 4399 t of PM, 1943 t of HCl, 9916 kg of Pb, 5901 kg of Mn, 4805 kg of Cu, 3574 kg of Cr, 3329 kg of Ni, 2154 kg of Hg, 1168 kg of Cd, 862 kg of As, 409 kg of Co, 216 kg of Sb, 13 kg of Tl, and 19 g toxic equivalent quantity of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans were emitted from 337 MSWI plants scattered in 30 provinces of mainland China in 2017, respectively. HAPs emissions were heavily concentrated in developed coastal provinces and cities. Scenario analysis highlighted the importance of continuous improvement and upgrade on advanced air pollution control devices and MSWI management to meet the future ultra-low emission limits and minimize the harmful impacts of HAPs on atmospheric environment and public health.

Design of step grate firing by utilizing palm empty-fruit-bunch fuel for industrial steam boiler construction

To achieve desired performance of steam boiler and low emission of hazardous air pollutants for generating electric power from palm oil industry, combustion characteristics of grate firing should be optimal for difficult biomass fuels. This article aims to present a design of step grate firing with high thermal efficiency for combustion of selected palm empty fruit bunch (EFB) fuel with moisture content of 38.4% and ash content of 3.39%. The proposed grate firing is not only specially designed for continuous 3-month operation but also particularly suited to construction of an industrial boiler rated at 80 tons/h, 45 bar, and 430 °C. The reciprocating step grate as well as air distribution for optimized combustion characteristics is specified based on computational fluid dynamics (CFD) analysis and practical experience. The required boiler can be successfully constructed and smoothly operated by installing the designed step grate firing as part of a whole system at a biomass power plant in Thailand.

Estimation of Emission Factors for Hazardous Air Pollutants from Petroleum Refineries

The hazardous air pollutants (HAPs) group is composed of 187 chemicals that are known to be potentially carcinogenic and dangerous for human health. Due to their toxicological impact, HAPs are an increasingly studied class of compounds. Of the different HAPs sources, refineries are one of the major sources. In order to obtain a preliminary assessment of the impact of a refinery in terms of emissions, a useful instrument is the determination of the emission factor (EF). For this reason, this work, focusing on the USA refining scenario, aims to provide evidence for a generic trend in refinery emissions to evaluate a correlation between the plant size and the amount of its emissions, in particular the HAPs emissions. Based on the analysis of the data collected from the U.S. Environmental Protection Agency (US EPA), a general trend in the emissions from refinery plants was established, showing a positive correlation between the HAPs emissions and the refinery size, represented by a value of the Pearson correlation coefficient r close to 1. Once this correlation was highlighted, a purpose of this work became the estimation of an organic HAPs emission factor (EF): from a whole refining plant, the EF of the total organic HAPs is equal to 10 g emitted for each ton of crude oil processed. Moreover, it was also possible to undertake the same evaluation for two specific HAP molecules: benzene and formaldehyde. The benzene and formaldehyde EFs are equal to, respectively, 0.8 g and 0.2 g for each ton of processed crude oil. This work provides a simple rule of thumb for the estimation of hazardous substances emitted from petroleum refineries in their mean operating conditions.

Balanced and sustainable development of ‘green’ business in regions, using the instruments of economic security

Subject. This article considers the development of ‘green’ entrepreneurship in the context of ensuring the economic security of Russian regions. Objectives. We focus on developing a conceptual and instrumental basis for sustainable development of entrepreneurial segments of the ‘green’ economy, using the economic security tools for rapid identification and ranking of new threats and risks. Methods. The study rests on the methodology for determining the confidence interval to create threshold values of indicators of economic security and "green" entrepreneurship, supplemented by trend analysis to justify the priority of introducing ‘green’ entrepreneurship mechanisms in a particular region of the Russian Federation. Results. We underpin the priority of introducing mechanisms for ‘green’ entrepreneurship development, through modeling upper and lower boundaries of permissible values for indicator of air pollutant emissions from stationary sources, in the Moscow, Leningrad, Sverdlovsk, and Novosibirsk Oblast, and the Altai and Krasnodar Territory. Conclusions. Based on generalization and systematization of Russian and foreign experience, we provide a theoretical rationale for the content, role, classification, and interdependence of tools for sustainable development of business segments of the ‘green’ economy, clarify the concept of ‘sustainable development’ for the purposes of this study. We prove the hypothesis that priority support need those regions that incur the greatest risks in the environmental sphere, including large volumes of hazardous air pollutant emissions.

Estimating future industrial emissions of hazardous air pollutants in the United States using the National Energy Modeling System (NEMS)

Retrospective studies such as the National Air Toxics Assessment have focused on modeling hazardous air pollutant (HAP) concentrations and exposures in the near past; however, future projections of HAPs emissions are relatively unexplored compared to those for greenhouse gases or criteria pollutants, and HAPs are typically not included in energy systems optimization or integrated assessment modeling. In this study, we demonstrate a method that harnesses sector-based emissions data from the US environmentally extended input-output (USEEIO) model and scenario results from the National Energy Modeling System (NEMS) to project HAPs emissions from industrial sectors in United States, disaggregated to 9 regions. The results show that most HAPs have higher projected emissions in 2050 compared to the baseline year when assuming constant emissions intensities per unit of economic output, but lower emissions when trend values for pollution control and technology improvements are incorporated. Regional and temporal patterns are diverse among the 237 HAPs considered. Using formaldehyde as a prominent example, the oil and gas sector is the largest national contributor (49%-77%) to future formaldehyde emissions across scenarios. Overall, this method enables projections of industrial HAPs emissions, aligned with official NEMS scenarios, that can be used in assessments of future air quality and potential health impacts from HAPs.

Atmospheric emission inventory of hazardous air pollutants from biomass direct-fired power plants in China: Historical trends, spatial variation characteristics, and future perspectives

The agricultural and forestry biomass direct-fired power generation represents an important technology to promote the low-carbon energy transition and agricultural waste reuse in China. In recent years, emissions of hazardous air pollutants (HAPs) caused by the rapid biomass industrialization have attracted increasing attention. To investigate the characteristics of HAPs emitted from biomass power plants in China, a multiple-year comprehensive emission inventory including NOx, SO2, PM, PM10, PM2.5, and trace elements (As, Cd, Cr, Cu, Hg, Pb, Zn) has been established for the period of 2006–2017. As a result of the emission standard (GB13223-2011), emissions of conventional HAPs have declined since 2014. The results show that national total emissions in 2017 were estimated at 29,516.0 t of NOx, 14,192.1 t of SO2, 4100.7 t of PM, 2353.9 t of PM10, 1630.6 t of PM2.5, 3057.2 kg of As, 1622.8 kg of Cd, 8285.8 kg of Cr, 54,443.4 kg of Cu, 132.9 kg of Hg, 66,325.8 kg of Pb, and 175,587.9 kg of Zn, respectively. The majority of HAPs emissions have been concentrated in eastern, northeastern, and central areas of mainland China. Shandong, Heilongjiang, and Anhui represent the top three provinces with the highest HAPs emissions from 2012 to 2017. Besides, the future emissions in 2025 and 2035 under the ultra-low emission policy are predicted with scenario analysis.

Microalgae Cultivation Technologies as an Opportunity for Bioenergetic System Development—Advantages and Limitations

Microalgal biomass is currently considered as a sustainable and renewable feedstock for biofuel production (biohydrogen, biomethane, biodiesel) characterized by lower emissions of hazardous air pollutants than fossil fuels. Photobioreactors for microalgae growth can be exploited using many industrial and domestic wastes. It allows locating the commercial microalgal systems in areas that cannot be employed for agricultural purposes, i.e., near heating or wastewater treatment plants and other industrial facilities producing carbon dioxide and organic and nutrient compounds. Despite their high potential, the large-scale algal biomass production technologies are not popular because the systems for biomass production, separation, drainage, and conversion into energy carriers are difficult to explicitly assess and balance, considering the ecological and economical concerns. Most of the studies presented in the literature have been carried out on a small, laboratory scale. This significantly limits the possibility of obtaining reliable data for a comprehensive assessment of the efficiency of such solutions. Therefore, there is a need to verify the results in pilot-scale and the full technical-scale studies. This study summarizes the strengths and weaknesses of microalgal biomass production technologies for bioenergetic applications.

Air quality status during 2020 Malaysia Movement Control Order (MCO) due to 2019 novel coronavirus (2019-nCoV) pandemic

An outbreak of respiratory illness which is proven to be infected by a 2019 novel coronavirus (2019-nCoV) officially named as Coronavirus Disease 2019 (COVID-19) was first detected in Wuhan, China and has spread rapidly in other parts of China as well as other countries around the world, including Malaysia. The first case in Malaysia was identified on 25 January 2020 and the number of cases continue to rise since March 2020. Therefore, 2020 Malaysia Movement Control Order (MCO) was implemented with the aim to isolate the source of the COVID-19 outbreak. As a result, there were fewer number of motor vehicles on the road and the operation of industries was suspended, ergo reducing emissions of hazardous air pollutants in the atmosphere. We had acquired the Air Pollutant Index (API) data from the Department of Environment Malaysia on hourly basis before and during the MCO with the aim to track the changes of fine particulate matter (PM2.5) at 68 air quality monitoring stations. It was found that the PM2.5 concentrations showed a high reduction of up to 58.4% during the MCO. Several red zone areas (>41 confirmed COVID-19 cases) had also reduced of up to 28.3% in the PM2.5 concentrations variation. The reduction did not solely depend on MCO, thus the researchers suggest a further study considering the influencing factors that need to be adhered to in the future.

Hazardous air pollutant emissions implications under 2018 guidance on U.S. Clean Air Act requirements for major sources

ABSTRACT On January 25, 2018, the United States Environmental Protection Agency withdrew a 1995 policy that mandates the use of maximum achievable control technology (MACT) to regulate emissions from major sources of hazardous air pollutants (HAPs), a category of toxic chemicals that may be carcinogenic, mutagenic, or cause other adverse health effects. To better understand the implications and scope of the change in regulatory guidance for HAP emissions of major sources that may reclassify as area sources, the increase in emissions that could legally occur under the new policy is assessed here. Based on facility-level data from a 2014 HAP national emissions inventory, it is estimated that 70% of major sources of HAPs qualify for reclassification as area sources, which could result in a maximum of 35,030 tons per year (tpy) of additional HAP emissions if all sources successfully reclassified. This amount would nearly triple the total volume of HAPs that qualifying major sources emitted in 2014. On average, qualifying sources could emit individually an additional 18.4 tpy. In the 21 states and territories that follow only federal guidelines for controlling HAPs, it is more likely that the estimates presented here could materialize compared to states that have additional guidelines for area sources of HAPs. The quantitative analysis of the potential emission changes resulting from regulatory change is instructive for industry, state and federal decisionmakers, and interested members of the public looking to understand and anticipate how relevant stakeholders will be affected by this policy change. Implications: Withdrawal of a U.S. Environmental Protection Agency policy that mandates the use of maximum achievable control technology (MACT) to regulate emissions from major sources of hazardous air pollutants (HAPs) could result in higher emissions of toxic chemicals that may be carcinogenic, mutagenic, or cause other adverse health effects. Analysis of potential emission changes resulting from regulatory change is instructive for industry, state, and federal decisionmakers, and interested members of the public looking to understand and anticipate how relevant stakeholders will be affected by this policy change.

Understanding the emission pattern and source contribution of hazardous air pollutants from open burning of municipal solid waste in China

The open burning of municipal solid waste (MSW) is common in China. Therein, low–temperature anoxic combustion results in the emission of hazardous air pollutants. This study employed a dilution sampling system to conduct open burning testing on MSW samples from different functional urban areas. Additionally, modified combustion efficiency was used to distinguish smoldering and flaming combustion in two of the most common open burning practices in China: pile–up burning and barrel burning. The sampled pollutants included gaseous pollutants (e.g., CO2, CO, SO2, and NOx) and fine particles (PM2.5). This study also analyzed the carbonization compounds, 9 water–soluble ions, and 8 toxic heavy metals in PM2.5. Emission factors of air pollutants from open burning of different MSW compositions and burning modes were determined. The composition of PM2.5 from MSW open burning comprised average 43.9%, 22.5%, and 0.4% of organic carbon (OC), water–soluble ions, and toxic heavy metals (THMs), respectively. OC was found to be the primary component of PM2.5. Based on localized emission factor database, the emissions and source contribution of open burning of MSW in China were quantified. The open burning of MSW can contribute averaged 8.7%, 16.7%, 3.8%, 1.3% of PM2.5, OC, THMs, and gaseous air pollutants of reported emissions of anthropogenic sources, respectively. This work can complement current anthropogenic emission inventory and assist policy–making.

Hazardous air pollutants emission characteristic and environmental effect of typical petrochemical incinerators

In this study, the emission of some hazardous pollutants including CO, CxHy, H2S, SO2, NOx and CO2 from six petrochemical incinerators (A to F) was studied in two different seasons, hot season (July 2015) and cold season (January 2016). The incinerators with various feeds and operating conditions are located in Petrochemical Special Economic Zone (PSEZ), south of Iran. Air pollutant dispersion model was implemented in this study to predict dispersion of each pollutant around the PSEZ. Measurement results showed that incinerators C and F had the lowest and the highest emission rate in hot and cold seasons, respectively. Also, according to the height of incinerator stacks, the incinerator F is the shortest incinerator that emits remarkable NOx with low flow rate which is an environmental issue. The air modeling indicated the influence of wind direction and also the effect of each incinerator on the concentration distribution of gasses. Almost all the pollutants specially CxHy were seen at high concentrations in the residential area around the PSEZ and affected the surrounding air quality. Since the wind direction in the whole year is mostly toward the north, east and south directions, most of the pollutants moved toward the residential areas.

Landfill reactions to society actions: The case of local and global air pollutants of Cerro Patacón in Panama

This paper studies landfill emissions and the related environmental and health risks in Panama City, with the aim to sensitize the population about the harmful effects of irresponsible resource consumption and non-deliberate solid waste generation that it is disposed of in an uncontrolled manner in landfills. Empirical data on Cerro Patacón, Panama City's landfill was obtained to describe the status of municipal waste disposal. Ten known methane generation models were used to estimate the yearly emission rate of methane from the landfill for a 100-year period starting from its inception in 1986. From the models used, the GasSIM model was chosen to estimate emission rates of six long-term hazardous air pollutants. The AERMOD source dispersion model was used to simulate their atmospheric downwind dispersion by levels of concentration over nearby affected communities; results were mapped in Google Earth. The relative contributions by population of the 32 towns making up Panama City to the forecasted waste generation in 2022 and related hazardous air pollutants emission rates from the landfill were assessed. It was found that Cerro Patacón will generate 45% of the countrywide methane generation by 2022; an average of 47 Gg. The solid waste generated by the 1.5 million inhabitants of Panama City impacts the health of ~73,600 inhabitants in nearby communities through the dispersion of hazardous atmospheric pollutants derived from the landfill. The highest emission rates were from hydrogen sulfide and dichloromethane, which can be largely attributed to the waste generated by the communities of Juan Diaz and Tocúmen. The concentration of hydrogen sulfide and benzene was over the reference concentration (uncertainty factor spanning three orders of magnitude) for all communities and years simulated. The concentration of vinyl chloride was over the RfC for all communities and years simulated, except in 2018 for 12 communities.

Atmospheric change as a driver of change in the Canadian boreal zone1

Global anthropogenic emissions of greenhouse gases and hazardous air pollutants have produced broad yet regionally disparate changes in climatic conditions and pollutant deposition in the Canadian boreal zone (the boreal). Adapting boreal resource management to atmospheric change requires a holistic understanding and awareness of the ongoing and future responses of terrestrial and freshwater ecosystems in this vast, heterogeneous landscape. To integrate existing knowledge of and generate new insights from the broad-scale impacts of atmospheric change, we first describe historical and present trends (∼1980–2015) in temperature, precipitation, deposition of hazardous air pollutants, and atmospheric-mediated natural disturbance regimes in this region. We then examine their associations with ecosystem condition and productivity, biological diversity, soil and water, and the carbon budget. These associations vary considerably among ecozones and likely undergo further changes under the emerging risks of atmospheric change. We highlight the urgent need to establish long-term, boreal-wide monitoring for many key components of freshwater ecosystems to better understand and project the influences of atmospheric change on boreal water resources. We also formulate three divergent future scenarios of boreal ecosystems in 2050. Our scenario analysis reveals multiple undesirable changes in boreal ecosystem structure and functioning with more variable atmospheric conditions and frequent land disturbances, while continuing business-as-usual management of natural resources. It is possible, though challenging, to reduce unwanted consequences to ecosystems through management regimes focussed on socio-ecological sustainability and developing resilient infrastructure and adaptive resource-management strategies. We emphasize the need for proactive actions and improved foresight for all sectors of society to collaborate, innovate, and invest in anticipation of impending global atmospheric change, without which the boreal zone will face a dim future.