Average Annual Emissions Research Articles

Economic and environmental pollutant impact of Maternal-Fetal Telemedicine.

The global issue of greenhouse gas emissions has significant implications for the environment and human health. Telemedicine provides a valuable tool for delivering healthcare while reducing gas emissions by limiting the need for patient travel. However, the environmental effects of telemedicine in high-risk pregnancy populations remain unassessed. The aim of this study was to estimate the economic and environmental impact of an outpatient teleMFM program. This retrospective cohort study examined all visits at 3 teleMFM clinics more than 90 miles away from the nearest in-person MFM office between 10/1/2021 and 6/1/2022. Travel distances and times were calculated for each appointment between the patient's home, telemedicine clinic, and nearest in-person clinics, using zip code data and Google Maps web-based map calculator tools. Travel cost savings and environmental impact were calculated by determining differences in mileage reimbursement rate and emissions between those incurred in attending telemedicine appointments and those that would have been incurred if in-person using inflation-adjusted Internal Revenue Service annual standard mileage reimbursement rate ($0.58 per mile), and the U.S. Environmental Protection Agency Office of Transportation and Air Quality's average annual emissions and fuel consumption for gasoline-fueled passenger vehicles. During the study period a total number of 2,712 appointments were scheduled, of which 2,454 were kept (cancellations removed) and analyzed. Visiting a teleMFM clinic resulted in 204 miles, 200 minutes and 118.32 dollars saved per patient visit compared to visiting the nearest in-person clinic. Over a 7 month period a total of 96.6 metric tons of emissions were saved. This study demonstrates the positive economic and environmental impact of teleMFM utilization in communities remote from in-person care. Given the contribution of greenhouse gas emissions to climate change, such findings may provide strategies for our specialty make informed policy, advocacy, and business decisions.

Development of 1 ×1 km gridded emission inventory for air quality assessment and mitigation strategies from open biomass burning in Karnataka, India

In this work, we have developed a high-resolution (1 ×1 km grid) emission inventory of greenhouse gases and air pollutants from open biomass burning (OBB) in Karnataka for 2000, 2005, 2010, 2015, 2020, and 2022. Secondary and field datasets were used to validate the emission inventories. The GIS-based statistical model and activity data were used to estimate greenhouse and air pollutant gas emissions from OBB (Forest, grassland, and crop fires). The uncertainty analysis of the emissions were done using the Monte Carlo Simulation (MCS) model and Low Emission Analysis Platform (LEAP) tool was used for projecting the emissions to 2050 based on the annual average growth rate. According to our results, the total OBB burned areas (%) in Karnataka during the aforementioned years were 24.43, 15.69, 15.95, 11.41, 26.73, and 5.78. The results showed that total annual average OBB emissions in Karnataka for 2000–2022 in Gg were SO2 (6.67), NOx (9.48), NH3(9.80), CO (670.12), OC (59.78), BC (5.09), CO2 (11071 .11), CH4(33.68), PM10(84.29), PM2.5(81.08), NMVOC (74.13), and NO2 (4.80) respectively. The districts of Kalburgi, Raichur, Bagalkot, Uttara Kannada, and Shivamogga have the highest emissions from OBB in Karnataka from 2000 to 2022. The emission uncertainty results showed ±26.92, ±28.17, and ±30.27 % for the crop, grassland, and forest fires, respectively. Under the business-as-usual (BAU) scenarios, the CH4 emissions from forest, grassland, and crop fires are projected at 8823, 2.64, and 5262 metric tonnes by 2030 and 58046, 10, and 30700 metric tonnes by 2050, respectively. The developed high-resolution inventories are the most up-to-date surface emission datasets with hotspots in Karnataka from OBB emission. National Clean Air Programme (NCAP) and India’s Net-Zero Emission target by 2070, our high-resolution emission inventories and mitigation strategies may be helpful for air quality monitoring, health benefits analysis, and policy-making studies in Karnataka, India.

Applying trade mechanisms to quantify dynamic GHG emissions of electricity consumption in an open economy - The case of Switzerland

Quantifying greenhouse gas (GHG) emissions from electricity consumption presents a significant challenge due to the variable nature of the generation mix throughout the year and the complex dynamics of cross-border electricity trade. In this paper, we introduce an innovative methodology designed to accurately capture the hourly GHG emissions linked to electricity imports, and thus electricity consumption. Contrary to conventional approaches, our methodology identifies the relevant generation technologies in exporting countries which are activated for export. This selection is based on (i) the classification of the technologies according to their dispatch cost (merit order), and (ii) considers trade mechanisms from economic theory.We apply this methodology to Switzerland, a country characterized by a low-carbon electricity generation mix, which however heavily relies on imports from neighbouring countries, particularly during the winter months. Over the period from 2017 to 2021, we find that 88 % of Switzerland's domestic electricity demand is met by its own generation—primarily hydro and nuclear—while the remaining 12 % is imported, mainly from fossil-fuel-based sources. Consequently, the average annual GHG emission factor for electricity consumption in Switzerland is 98 g-CO2eq/kWh, with 29 % attributed to domestic generation and 71 % to imports. This figure is 40 % higher than the 70 g-CO2eq/kWh estimated using a conventional approach, which typically underestimates the specific impacts of electricity imports.The disparity between these approaches becomes even more pronounced when considering the seasonal and hourly variations in the electricity mix and the resulting emission factors. These insights are particularly crucial in the context of emerging electricity demands, such as heat pumps and electric vehicles, where accurate GHG accounting can significantly influence policy and investment decisions.

Life cycle carbon emission assessment and carbon payback period analysis for the regeneration of old residential areas in cold regions: Case study in Qingdao, China

Communities urgently need to explore green and low-carbon transformation pathways due to high energy consumption and carbon emissions. However, existing studies lack a comprehensive assessment of carbon emissions and analysis regarding carbon reduction during renovation of old residential areas in cold regions. Therefore, this study employs a Life Cycle Assessment (LCA) and the payback period method to evaluate carbon emissions throughout the life cycle comprehensively. It constructs a carbon-emission calculation model based on LCA, specifically tailored to the retrofitting of old residential areas in cold cities. Additionally, it investigates the effectiveness of three typical retrofit measures undertaken in Qingdao, a region located in the cold A zone, focusing on whole-life-cycle energy savings and carbon reduction. The findings reveal that the average annual carbon emission intensity per unit area for Cases 1, 2, and 3 is 12.59 kg-CO2 e/(m2·a), 27.05 kg-CO2 e/(m2·a), and 23.39 kg-CO2 e/(m2·a), respectively. Their corresponding carbon payback periods were 6.06, 7.23, and 16.00 years, respectively, which could be further shortened through material recycling. The environmental impact assessment of typical retrofitting measures contributes to the promotion of sustainable development. Furthermore, this study offers guidance for establishing an effective assessment system that supports the design of energy-saving retrofits.

Heat-integrated extractive distillation for separating tetrahydrofuran/methanol/water with ionic liquid-based mixed entrainer: Molecular mechanism and process integration

Tetrahydrofuran (THF) and methanol (MeOH) are commonly used raw materials and reagents in the chemical industry, but the azeotropic phenomenon between the two components makes it challenging to achieve high-purity separation. This study separated THF/MeOH/H2O mixtures by heat-integrated extractive distillation using an ionic liquid-based mixed entrainer (ILME). The dimethyl sulfoxide (DMSO) was determined by relative volatility analysis, and IL [EMIM][AC] was screened from 240 ionic liquids according to the COSMOtherm 2021 software. The separation mechanism was investigated at the molecular level (i.e., IGM analysis, polarisation charge density (σ-profile), electrostatic potential (ESP), interaction energy, and quantum chemical theory), which demonstrated that the rationality and strength of the interaction between the entrainer and the separated system were conducive for the separation to proceed. Single DMSO, ILME indirect extractive distillation (IED) and direct extractive distillation (DED) were designed and optimized, and further heat-integrated optimization (HI-DED) was performed on the ILME direct extractive distillation process. The results showed that HI-DED reduced the average annual total energy consumption, energy utilization and CO2 emissions by 23.23%, 26.24% and 26.24%, respectively, compared to the conventional direct extraction distillation process. The HI-DED process using ILME significantly reduces economic, energy consumption and CO2 emissions compared to conventional extractive distillation and has great potential for industrial applications.

Exploring Synergistic GHG Emissions Mitigation Potential and Costs of Room Air Conditioners.

This study explores the potential of synergistically reducing direct (refrigerant) and indirect (electricity) greenhouse gas (GHG) emissions in the global room air conditioning (RAC) sector, based on 80% of global RAC manufactured in China. Three scenarios are evaluated: Business-as-usual (BAU) based on maintaining refrigerant and energy efficiency levels from 2021 China RAC sales shares, Kigali Amendment compliant with 10% energy efficiency improvement by 2025 (KAE), and accelerated refrigerant transition and energy efficiency improvement (ATE). Each scenario considers the costs of refrigerant and efficiency measures for export market groups based on Kigali Amendment classifications. BAU predicts around 1 Gt CO2-eq average annual global RAC emissions (2022-2060). Cumulative emission reductions in China's RAC manufacturing under KAE and ATE are 12.2 and 17.2 Gt CO2-eq A5II and A5I (except China), presenting cost-effective abatement measures, with average costs of -$51.4 and -$68.8/t CO2-eq in KAE and ATE. Cumulative average abatement costs are around $18 and $4/t CO2-eq globally. KAE and ATE scenarios would avoid surface temperature rises of 0.023 (±0.002) °C and 0.027 (±0.003) °C, respectively, versus BAU. Collaboration between China and importing countries is urged to enhance energy efficiency in RACs traded, ensuring sustainable mitigation aligned with the Kigali Amendment.

High-resolution satellite estimates of coal mine methane emissions from local to regional scales in Shanxi, China

Coal mines are significant anthropogenic sources of methane emissions, detectable and traceable from high spatial resolution satellites. Nevertheless, estimating local or regional-scale coal mine methane emission intensities based on high-resolution satellite observations remains challenging. In this study, we devise a novel interpolation algorithm based on high-resolution satellite observations (including Gaofen5-01A/02, Ziyuan-1 02D, PRISMA, GHGSat-C1 to C5, EnMAP, and EMIT) and conduct assessments of annual mean coal mine methane emissions in Shanxi Province, China, one of the world's largest coal-producing regions, spanning the period 2019 to 2023 across various scales: point-source, local, and regional. We use high-resolution satellite observations to perform interpolation-based estimations of methane emissions from three typical coal-mining areas. This approach, known as IPLTSO (Interpolation based on Satellite Observations), provides spatially explicit maps of methane emission intensities in these areas, thereby providing a novel local-scale coal mine methane emission inventory derived from high-resolution top-down observations. For regional-scale estimation and mapping, we utilize high-resolution satellite data to complement and substitute facility-level emission inventories for interpolation (IPLTSO+GCMT, Interpolation based on Satellite Observations and Global Coal Mine Tracker). We evaluate our IPLTSO and IPLTSO+GCMT estimation with emission inventories, top-down methane emission estimates from TROPOMI observations, and TROPOMI's methane concentration enhancements. The results suggest a notable right-skewed distribution of methane emission flux rates from coal mine point sources. Our IPLTSO+GCMT estimates the annual average coal mine methane emission in Shanxi Province from 2019 to 2023 at 8.9 ± 0.5 Tg/yr, marginally surpassing top-down inversion results from TROPOMI (8.5 ± 0.6 Tg/yr in 2019 and 8.6 ± 0.6 Tg/yr in 2020). Furthermore, the spatial patterns of methane emission intensity delineated by IPLTSO+GCMT and IPLTSO closely mirror those observed in TROPOMI's methane enhancements. Our comparative assessment underscores the superior performance and substantial potential of the developed interpolation algorithm based on high-resolution satellite observations for multi-scale estimation of coal mine methane emissions.

Study on the establishment of air pollutant and carbon emission inventory and collaborative emission reduction potential of China's coking industry from 2012 to 2022

Coking industry is usually regarded as a high pollution and high energy consumption industry. China is accelerating its efforts to reduce pollution and carbon emissions in the industrial sector, which has received little attention as the world's largest producer of coke. Therefore, in this study, the trend of air pollution and carbon emissions in China's coking industry and the path of coordinated emission reduction were studied. The results indicate that the average annual emissions of PM, SO2, NOx, VOCs, and CO2 in China's coking industry from 2012 to 2022 amount to 205.98, 69.47, 193.45, 599.80 Gg and 191.10 Tg, respectively. The main sources of PM, SO2, NOx, VOCs and CO2 in coking industry were coal preparation (51.5 %), charge and pushing (39.5 %), coke oven gas (99.8 %), byproduct recovery (47.0 %) and fuel combustion (87.5 %). The emissions from coking plants in central and southern Shanxi, eastern and southern Hebei, and central Shandong are the most concentrated. Ultra-low emission transformation and deep treatment of VOCs have greatly reduced pollutant emissions in key areas of air pollutant control, but the actual emission reduction effect of these measures has been weakened by the additional emissions caused by the increase of coke production in other non-key areas. The research on synergetic emission reduction path shows that there is a great synergistic benefit between air pollutants and CO2 emission reduction in coking industry. It is estimated that the APeq (air pollutants and carbon equivalent) of China's coking industry in 2025, 2028 and 2030 will decrease by 38.2 %, 63.5 % and 70.8 % respectively compared with 2022. With the continuous promotion of pollution reduction and carbon reduction measures, the emission reduction potential of China's coking industry will gradually shift from key areas to non-key areas.

Potential assessment of CO2 source/sink and its matching research during CCS process of deep unworkable seam

It is of great significance for the engineering popularization of CO2-ECBM technology to evaluate the potential of CCUS source and sink and study the matching of pipeline network of deep unworkable seam. In this study, the deep unworkable seam was taken as the research object. Firstly, the evaluation method of CO2 storage potential in deep unworkable seam was discussed. Secondly, the CO2 storage potential was analyzed. Then, the matching research of CO2 source and sink was carried out, and the pipe network design was optimized. Finally, suggestions for the design of pipe network are put forward from the perspective of time and space scale. The results show that the average annual CO2 emissions of coal-fired power plants vary greatly, and the total emissions are 58.76 million tons. The CO2 storage potential in deep unworkable seam is huge with a total amount of 762 million tons, which can store CO2 for 12.97 years. During the 10-year period, the deep unworkable seam can store 587.6 million tons of CO2, and the cumulative length of pipeline is 251.61 km with requiring a cumulative capital of $ 4.26 × 1010. In the process of CO2 source-sink matching, the cumulative saving mileage of carbon sink is 98.75 km, and the cumulative saving cost is $ 25.669 billion with accounting for 39.25% and 60.26% of the total mileage and cost, respectively. Based on the three-step approach, the whole line of CO2 source and sink in Huainan coalfield can be completed by stages and regions, and all CO2 transportation and storage can be realized. CO2 pipelines include gas collection and distribution branch lines, intra-regional trunk lines, and interregional trunk lines. Based on the reasonable layout of CO2 pipelines, a variety of CCS applications can be simultaneously carried out, intra-regional and inter-regional CO2 transport network demonstrations can be built, and integrated business models of CO2 transport and storage can be simultaneously built on land and sea. The research results can provide reference for the evaluation of CO2 sequestration potential of China's coal bases, and lay a foundation for the deployment of CCUS clusters.

Mercury Discharge Inventory Based on Sewage Treatment Process in China

Mercury pollution is a serious public health problem. China’s extensive use and reliance on mercury has led to water pollution, particularly the presence of methylmercury in water. Estimating total mercury emissions from wastewater in China is challenging due to the large amount and wide range of emissions. An estimation model for total mercury content in sewage in China was established by establishing a relationship between sewage treatment volume, mercury content in effluent after sewage treatment, and the data of sludge production and mercury content in the sewage treatment plant. It was determined that only 3% of mercury entered the air during sewage treatment, 27.5% of mercury entered the effluent, and about 69.5% of mercury entered the sludge, based on the treatment of existing wastewater treatment plants in China. From 2002 to 2021, the average annual sewage mercury emission in China was 32.07 Mg, and the emissions were higher in densely populated and economically developed provinces such as Beijing, Shandong, Hebei, and Guangdong. By 2025, China’s mercury emissions are projected to reach 55.41 Mg. By 2035, China’s mercury emissions are projected to reach 49.3 Mg.

Estimation of Potential Nitrous Oxide Emissions from Landfills in the United States: 2010–2020

Nitrous oxide (N2O), a major greenhouse gas, has the potential to be emitted from waste landfills. Previous studies have demonstrated the propensity of landfilling facilities to emit significant quantities of N2O, a fact underscored by the IPCC Guidelines, which emphasize the importance of researching this phenomenon. However, due to the absence of established international guidelines for quantifying N2O emissions from landfills, many countries, including the United States, have excluded N2O from greenhouse gas inventories. Therefore, this study aims to estimate N2O emissions from landfills in the United States, a country with a significant landfill waste volume. In this study, N2O emissions from U.S. landfills over an 11-year period (2010–2020) are estimated by using the emission estimation formula provided in CDM AM0083 and emission factors from the 2006 IPCC Guidelines. Additionally, emissions were calculated spatially for each state and individual landfill facility. As a result, the impact of integrating N2O emissions from landfills into the national greenhouse gas inventory was assessed. The average annual landfill N2O emission in the United States over the 11-year period was estimated to be 3,214,693 ton-CO2-equivalent/year, with an overall decreasing trend. In 2020, Indiana, Michigan, and Oregon exhibited high landfill N2O emissions per capita, while the Virgin Islands, Connecticut, and Massachusetts demonstrated lower emissions. When incorporated into the U.S. greenhouse gas inventory, landfill N2O emissions represent 10.41% of the total sector N2O emissions. Although N2O emissions are declining alongside reduced waste landfilling in the United States, the quantity remains significant and should be factored into greenhouse gas inventory calculations and emission scenarios for the next CMIP6. Further research investigating N2O emission coefficients across different regions and waste types is necessary. Ultimately, this study aims to support the United Nations (UN)’s Sustainable Development Goals (SDGs), particularly SDG 11 (Sustainable Cities and Communities), 12 (Responsible Consumption and Production), and 13 (Climate Action), by enhancing the tools for accurate greenhouse gas inventory and promoting sustainable waste management.

Can China's carbon generalized system of preferences reduce urban residents' carbon emissions? Evidence from a quasi-natural experiment

The carbon generalized system of preferences (CGSP) is an innovative incentive mechanism implemented by the Chinese government, which has also become an important part of carbon emission reduction at the living end, and it is of great significance to study whether the Pilot Policy can reduce the carbon emissions of residents. This study firstly accounts for the total carbon emissions and per capita carbon emissions of the residents of 284 cities in China, and on this basis, adopts the SCM method to quantitatively study and analyze the overall and local implementation effects of CGSP in China by taking the first batch of CGSP pilots in China as an example, and further applies the mediation effect model to test the pathways of the role of CGSP. The main findings of the study are as follows: (1) During the period of 2010–2020, the total carbon emissions from urban residents' living in China showed a yearly growth trend, from 36,623.98 ×10−2Mt in 2010–85,241.20 ×10−2Mt in 2020, an increase of 8.83%. Total carbon emissions present a structural difference of "electricity consumption > central heating > private transport > gas (oil, natural gas) consumption". (2) Overall, the implementation of the CGSP had a robust positive impact on the overall carbon emission reduction in the pilot cities, with an average annual emission reduction effect value of 36.53 ×10−2Mt. Locally, the annual net policy effect values of Dongguan, Zhongshan, Heyuan, and Guangzhou are 6169.79 ×10−2, 26,600.17 ×10−2, 17,081.34 ×10−2 and 9393.36 ×10−2Mt respectively. (3) CGSP has a good carbon emission reduction effect by suppressing the impact on residents' carbon emissions through enhancing the city's innovation capacity and promoting electricity saving and consumption reduction, while the mediating effect played by the promotion of green and low-carbon travel in the pilot policy is not significant. Finally, based on the research findings, relevant suggestions are targeted.

A holistic life cycle assessment of steel bridge deck pavement

Transportation serves as a cornerstone of economic development and is a significant contributor to carbon emissions. This study established a life cycle assessment model that incorporates refined carbon emission calculation parameters, streamlining the computation process while maintaining precision. A case study was conducted to quantify the life-cycle CO2 emissions of steel bridge deck pavements, a pivotal component within the transport network. The study suggests using the average annual CO2 emissions as a metric to gauge the carbon emission potential of steel bridge deck pavements with different service lives. This study addresses a void in the existing work by standardizing the grading of typical pavement diseases and quantifying the carbon emissions of the corresponding maintenance measures. It reveals that the pivotal determinant of life-cycle CO2 emissions for steel bridge deck pavements is the service performance of the paving material. Comparative analysis indicates that epoxy asphalt concrete could be deemed a low-carbon material, achieving a 77.6% reduction in life-cycle carbon emissions compared to gussasphalt concrete. Emissions during the maintenance phase constitute 66.7%–71.4% of the total life-cycle emissions, predominantly due to end-of-life and traffic delay units. The methodology and calculated data presented herein can inform subsequent carbon reduction strategies in transportation and promote the development of resilient infrastructure, thus making a substantial contribution towards carbon neutrality and climate change mitigation.

Enhanced efficiency nitrogen fertilizers (EENFs) can reduce nitrous oxide emissions and maintain high grain yields in a rain-fed spring maize cropping system

ContextEnhanced efficiency nitrogen fertilizers (EENFs) have provided opportunities for the simultaneous mitigation of nitrous oxide (N2O) emissions and increases in crop productions. However, the practice of combining EENFs with optimal fertilization under conditions of misaligned water and fertilizer inputs in rain-fed spring maize systems remains inadequately understood. ObjectiveThis study aims to determine the factors controlling N2O emissions under the soil climatic conditions in rain-fed plastic mulching cropping systems treated with different nitrogen (N) fertilization rates and EENFs, and to determine the most effective N fertilization measure to reduce N2O emissions while maintaining crop yields. MethodsA 3-year field experiment was conducted in a spring maize system located in the semiarid rain-fed region of the Loess Plateau, applying two types of EENFs: a nitrification inhibitor dicyandiamide (DCD) and a slow-release fertilizer (SRF). It comprised five fertilization treatments: unfertilized (CK), conventional N rate (CON, 200 kg N ha−1), optimal N rate (OPT, 160 kg N ha−1), OPT with the addition of DCD (OPT+DCD), and OPT using SRF (OPT-SRF). ResultsThe average annual cumulative N2O emissions over the 3-year experimental period ranged from 0.74 to 1.87 kg N2O-N ha–1. Fertilizer N contributed 26−60% to annual N2O emissions. The highest N2O fluxes (50–161 μg N2O-N m–2 h–1) typically occurred within the initial 10 days following fertilization, likely induced by strong nitrification processes, constituting 12–19% of the annual N2O emissions during this brief period. In comparison to the CON treatment, the OPT, OPT+DCD, and OPT-SRF treatments resulted in significant reductions in annual N2O emissions of 24%, 46%, and 34%, respectively, without causing any significant decrease in maize grain yields. The application of DCD led to increased ammonium (NH4+-N) concentrations while reducing nitrate (NO3–-N). Conversely, using SRF resulted in a decrease in both NH4+-N and NO3–-N concentrations. ConclusionsUsing EENFs at the ideal fertilization rate significantly curtailed yearly N2O emissions without adversely affecting maize yields in a rain-fed plastic mulching spring maize system prevalent in the Loess Plateau. Most N2O emissions occurred post-fertilization, with rainfall events further influencing these emissions. ImplicationsOur findings recommend the incorporation of nitrification inhibitors, such as DCD, as the most effective fertilizer measure for reducing N2O emissions in the rain-fed region of the Loess Plateau.

Assessment of the CO2 sequestration and emission potential of the Kari classified forest, Burkina Faso

ABSTRACT The aim of this study was to assess changes in the CO2 sequestration and emission capacities of the Kari classified forest. To this end, a study of land use dynamics was carried out using Landsat images from 2000, 2010 and 2019. To assess wood potential and CO2 emissions, a forest inventory was carried out by sampling. The data on vegetation dynamics and wood potential show that more than 90% of the vegetation in this forest has remained stable from 2000 to 2019. However, significant degradation of the vegetation has been recorded in shrub savannahs, tree savannahs and gallery forests. The assessment of wood potential indicates that the forest is stable, balanced and in full recovery. The forest constitutes a carbon dioxide reservoir, with approximately 2.35 MtCO2eq sequestered in 2019. The assessment also reveals that the degradation of the vegetation has led to significant CO2 emissions. Between 2000 and 2010, the study area emitted an average of 94,566 tCO2eq, i.e., an average annual emission of 9,456.6 tCO2eq. The results of this study confirm that the conservation actions carried out by the various stakeholders are making an effective contribution to protecting nature and the services it provides.

Ammonia distribution and ecological risk assessment in nine fresh lakes in China.

With the development of industry and economy, ammonia nitrogen pollutions in surface water are of great concern worldwide. This study investigated the historical contents of total ammonia nitrogen (TAN) and unionized ammonia molecules (NH3) in nine fresh lakes in China during 2014-2022. Three different classification methods (flood season, season, and geographical distribution) were used to analyze the concentration variation of TAN and NH3. The concentration of TAN first decreased and then increased in the flood season, showing a lower concentration in summer and a higher concentration in winter. The variation trend of NH3 was in an opposite way with TAN. Correlation analysis between ammonia and 10 water quality parameters and 4 pollution emission and treatment parameters showed that the correlation coefficient between TAN and total phosphorus (total nitrogen) was 0.44 (0.43), respectively. The correlation coefficients between average annual TAN concentration and total emissions (waste water treatment input) were 0.35 (0.53), respectively. Combined with ecotoxicity data from a series of aquatic species, the ecological risks of TAN and NH3 in lakes were evaluated using hazard quotient and joint probability curve methods. From 2014 to 2022, the probability of 5% species affected in the acute ecological risk of TAN and NH3 is lower than 0.01, but for the chronic ecological risk of TAN and NH3, the probabilities of 5% species affected are 0.003-0.030 and 0.04-0.14, respectively. The chronic ecological risks were higher than the acute ecological risks, and high risks in plateau lakes like Dianchi Lake should be paid more attention to.

Regional to global distributions, trends, and drivers of biogenic volatile organic compound emission from 2001 to 2020

Abstract. Biogenic volatile organic compounds (BVOCs) are important precursors to ozone and secondary organic aerosols in the atmosphere, affecting air quality, clouds, and climate. However, the trend in BVOC emissions and driving factors for the emission changes in different geographic regions over the past 2 decades has remained unclear. Here, regional to global changes in BVOC emissions during 2001–2020 are simulated using the latest Model of Emission of Gases and Aerosols from Nature (MEGANv3.2) with the input of time-varying satellite-retrieved vegetation and reanalysis meteorology data. Comparison of model simulations with the site observations shows that the model can reasonably reproduce the magnitude of isoprene and monoterpene emission fluxes. The spatial distribution of the modeled isoprene emissions is generally comparable to the satellite retrievals. The estimated annual average global BVOC emissions are 835.4 Tg yr−1 with the emissions from isoprene, monoterpenes, sesquiterpenes, and other BVOC comprised of 347.7, 184.8, 23.3, and 279.6 Tg yr−1, respectively. We find that the decrease in global isoprene emissions (−0.07 % per year) caused by the increase in CO2 concentrations (−0.20 % per year) is stronger than that caused by changes in vegetation (−0.03 % per year) and meteorological factors (0.15 % per year). However, regional disparities are large. Isoprene emissions increase significantly in Europe, East Asia, and South Asia (0.37 % per year–0.66 % per year). Half of the increasing trend is contributed by increased leaf area index (LAI) (maximum over 0.02 m2 m−2 yr−1) and tree cover. Changes in meteorological factors contribute to another half, with elevated temperature dominating in Europe and increased soil moisture dominating in East and South Asia. In contrast, in South America and Southeast Asia, shifts in vegetation type associated with the BVOC emission capacity, which partly results from the deforestation and agricultural expansion, decrease the BVOC emission and offset nearly half of the emission increase caused by changes in meteorological factors. Overall, isoprene emission increases by 0.35 % per year and 0.25 % per year in South America and Southeast Asia, respectively. In Central Africa, a decrease in temperature dominates the negative emission trend (−0.74 % per year). Global monoterpene emissions show a significantly increasing trend (0.34 % per year, 0.6 Tg yr−1) compared to that of isoprene (−0.07 % per year, −0.2 Tg yr−1), especially in strong greening hotspots. This is mainly because the monoterpene emissions are more sensitive to changes in LAI and are not subject to the inhibition effect of CO2. The findings highlight the important roles of vegetation cover and biomass, temperature, and soil moisture in modulating the temporal variations of global BVOC emissions in the past 2 decades.

Greenhouse gas emissions trends and drivers insights from the domestic aviation in Thailand

Domestic aviation is a swiftly expanding contributor to global greenhouse gas (GHG) emissions. Presently, economic volatility and the Coronavirus disease (COVID-19) crisis have resulted in the decline of domestic aviation, but domestic aviation is rapidly recovering in many countries. However, from a GHG emissions viewpoint, the domestic aviation sector is largely unenforced even though the International Civil Aviation Organization's (ICAO) Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) provision for international aviation is currently in place. Accordingly, the knowledge base on emissions and their drivers from domestic aviation is weak, especially in developing countries, thus hindering an evidence-based policy debate. In this context, we have estimated and analyzed the pre-COVID-19 GHG emissions and their trends from commercial domestic aviation in Thailand; and provided insights on the role of key drivers that influence GHG emissions that are expected to be useful not only for Thailand but also for other developing countries. Emissions are estimated following Intergovernmental Panel on Climate Change (IPCC) Tier-II. Specifically, activity-based landing/take-off (LTO) cycle and cruise. This is compared to the Tier-I method, and key drivers were analyzed using an index decomposition method. The total annual average GHG emissions for all LTO cycles and cruises of commercial domestic aviation for 2015–2020 was 2254 Th. tonnes of CO2-eq. During the LTO cycle of the aircraft, GHG emissions were at an average of 983 Th. tonnes of CO2-eq. Additionally, during the cruise stage, emissions averaged 1270 Th. tonnes of CO2-eq. The choice of accounting methods (i.e., IPCC Tier II vs. Tier I) seems to have had only nominal implications. Our analysis showed that, in the 2008–2020 period, the aviation activity effect and economic growth were the key decisive factors in this sector's GHG emissions growth. It was followed by the fuel energy intensity levels and the population effect in descending order of impact. These findings have significant ramifications for present and future policies aimed at decreasing GHG emissions, aiding Thailand in achieving its climate targets by 2050, and enhancing energy efficiency as the domestic aviation market adapts.

Two years of satellite-based carbon dioxide emission quantification at the world's largest coal-fired power plants

Abstract. Carbon dioxide (CO2) emissions from combustion sources are uncertain in many places across the globe. Satellites have the ability to detect and quantify emissions from large CO2 point sources, including coal-fired power plants. In this study, we routinely made observations with the PRecursore IperSpettrale della Missione Applicativa (PRISMA) satellite imaging spectrometer and the Orbiting Carbon Observatory-3 (OCO-3) instrument aboard the International Space Station at over 30 coal-fired power plants between 2021 and 2022. CO2 plumes were detected in 50 % of the acquired PRISMA scenes, which is consistent with the combined influence of viewing parameters on detection (solar illumination and surface reflectance) and unknown factors (e.g., daily operational status). We compare satellite-derived emission rates to in situ stack emission observations and find average agreement to within 27 % for PRISMA and 30 % for OCO-3, although more observations are needed to robustly characterize the error. We highlight two examples of fusing PRISMA with OCO-2 and OCO-3 observations in South Africa and India. For India, we acquired PRISMA and OCO-3 observations on the same day and used the high-spatial-resolution capability of PRISMA (30 m spatial/pixel resolution) to partition relative contributions of two distinct emitting power plants to the net emission. Although an encouraging start, 2 years of observations from these satellites did not produce sufficient observations to estimate annual average emission rates within low (<15 %) uncertainties. However, as the constellation of CO2-observing satellites is poised to significantly improve in the coming decade, this study offers an approach to leverage multiple observation platforms to better quantify and characterize uncertainty for large anthropogenic emission sources.

Double-battery configuration method for electric bus operation in cold regions

Managing the energy supply of electric buses (EBs) is critical to balance operational reliability and cost reduction. However, ambient temperature significantly affects energy consumption, posing challenges in providing adequate energy supply, especially in cold regions. In this study, we propose a double-battery configuration approach for EBs operating in cold regions with substantial temperature variations between seasons. The method involves utilizing a higher-capacity battery during winter months and a lower-capacity battery for summer operations. To determine the optimal fleet size, battery capacities, and EB scheduling plans in both winter and summer seasons, we formulate an integer programming model, focusing on minimizing the fleet's average annual operating costs (OC) and carbon emissions (CE). The model is solved using the branch and bound method. A case study is conducted, examining EB routes in 11 cold cities. Results reveal that the double-battery configuration method effectively reduces the fleet's average annual OC and CE. Specifically, the reduction ratio range for OC is from 3.34% to 5.18%, while the reduction ratio for CE ranges from 4.06% to 5.16%.