Anthropogenic Emission Sources Research Articles

Capture of CO2 at Thermal Power Stations as One of the Main Trends towards Reducing Anthropogenic Carbon Dioxide Emissions

The power industry, primarily its branch based on fossil fuel resources, is the major source of anthropogenic carbon dioxide emissions into the atmosphere of the planet. Based on direct measurements and some paleogeophysical data, it is shown that the carbon dioxide content in the atmosphere is currently increasing at a rate that exceeds by an order of magnitude its increase over the last several thousand years. Some methods for solving the global problem of reducing CO2 emissions caused by combustion of fossil fuels and basic technologies used for this purpose are considered. The main CO2 emission sources are identified. Based on the analysis of international statistical data, it is shown that large-scale fossil-coal-fired power-generating plants account for the greater part of the emissions. The existing CO2 capture technologies and those under development and intended for use in industrial power generation are compared and the prospects of their practical implementation are evaluated. The increase in the cost of the electric power generated within the full cycle of capturing CO2 from flue gases of large-scale power stations and storing it using the best-established technologies ready for introduction has been assessed. The basic factors that increase the cost of the power generated using the technologies for carbon dioxide emission sequestration have been determined and potential change in the prices in the future have been considered. The presented results suggest that the problem of drastic reduction in CO2 emissions requires a comprehensive approach and cannot be solved by efforts of only a limited number of industrially developed countries. The necessity of coordinated introduction of measures aimed at carbon dioxide emission sequestration not only in the “large-scale” power generation but also in other industries is shown.

Effect of different forage-to-concentrate ratios on ruminal bacterial structure and real-time methane production in sheep.

Emission from ruminants has become one of the largest sources of anthropogenic methane emission in China. The structure of the rumen flora has a significant effect on methane production. To establish a more accurate prediction model for methane production, the rumen flora should be one of the most important parameters. The objective of the present study was to investigate the relationship among changes in rumen flora, nutrient levels, and methane production in sheep fed with the diets of different forage-to-concentration ratios, as well as to screen for significantly different dominant genera. Nine rumen-cannulated hybrid sheep were separated into three groups and fed three diets with forage-to-concentration ratios of 50:50, 70:30, and 90:10. Three proportions of the diets were fed according to a 3 × 3 incomplete Latin square, design during three periods of 15d each. The ruminal fluid was collected for real-time polymerase chain reaction (real-time PCR), high-throughput sequencing and in vitro rumen fermentation in a new real-time fermentation system wit. Twenty-two genera were screened, the abundance of which varied linearly with forage-to-concentration ratios and methane production. In addition, during the 12-hour in vitro fermentation, the appearance of peak concentration was delayed by 26-27min with the different structure of rumen bacteria. The fiber-degrading bacteria were positively correlated with this phenomenon, but starch-degrading and protein-degrading bacteria were negative correlated. These results would facilitate macro-control of rumen microorganisms and better management of diets for improved nutrition in ruminants. In addition, our findings would help in screening bacterial genera that are highly correlated with methane production.

Tracing anthropogenic cadmium emissions: From sources to pollution

Cadmium (Cd), a widely concerned heavy metal, is toxic to humans and ecosystems. In this paper, a Cd-polluted town in southeast China was selected to estimate the Cd emissions of human activities into surface water, soil and atmospheric environment. The analysis shows that the total amount of Cd emitted into the environment in 2015 was approximately 43.5 kg, and the majority of those emissions were discharged into the water, accounting for approximately 90.4% of the total Cd emissions. The remaining Cd emissions into the soil and atmosphere accounted for 9.5% and 0.1%, respectively. The industrial production (IP) is the dominant source of anthropogenic Cd emissions, which contributes to 62.1% of the total emissions. The other contributors include aquaculture (AQ), wastewater treatment (WT), living consumption (LC), crop farming (CF) and animal breeding (AB); each accounted for less than 10% of the total emissions. Pigment production is the largest source of IP emissions. According to the results of correlation analysis, the pigment enterprises are responsible for the heavy Cd pollution in local soil. By comparing the spatial position and combing with the local watercourses, the study reveals that the irrigated watercourse is the transmission channels of soil Cd pollution. This study contributes to the analysis of connecting the emission inventory, environmental media and transmission channels of the heavy metal Cd and provides policy supports for the local governments to adopt a life cycle Cd management approach.

Contribution and uncertainty of sectorial and regional emissions to regional and global PM<sub>2.5</sub> health impacts

Abstract. In this work we couple the HTAP_v2.2 global air pollutant emission inventory with the global source receptor model TM5-FASST to evaluate the relative contributions of the major anthropogenic emission sources (power generation, industry, ground transport, residential, agriculture and international shipping) to air quality and human health in 2010. We focus on particulate matter (PM) concentrations because of the relative importance of PM2.5 emissions in populated areas and the well-documented cumulative negative effects on human health. We estimate that in 2010, depending on the region, annual averaged anthropogenic PM2.5 concentrations varied between ca. 1 and 40 µg m−3, with the highest concentrations observed in China and India, and lower concentrations in Europe and North America. The relative contribution of anthropogenic emission sources to PM2.5 concentrations varies between the regions. European PM pollution is mainly influenced by the agricultural and residential sectors, while the major contributing sectors to PM pollution in Asia and the emerging economies are the power generation, industrial and residential sectors. We also evaluate the emission sectors and emission regions in which pollution reduction measures would lead to the largest improvement on the overall air quality. We show that air quality improvements would require regional policies, in addition to local- and urban-scale measures, due to the transboundary features of PM pollution. We investigate emission inventory uncertainties and their propagation to PM2.5 concentrations, in order to identify the most effective strategies to be implemented at sector and regional level to improve emission inventories, knowledge and air quality modelling. We show that the uncertainty of PM concentrations depends not only on the uncertainty of local emission inventories, but also on that of the surrounding regions. Countries with high emission uncertainties are often impacted by the uncertainty of pollution coming from surrounding regions, highlighting the need for effective efforts in improving emissions not only within a region but also from extra-regional sources. Finally, we propagate emission inventory uncertainty to PM concentrations and health impacts. We estimate 2.1 million premature deaths per year with an uncertainty of more than 1 million premature deaths per year due to the uncertainty associated only with the emissions.

Towards a low CO2 emission building material employing bacterial metabolism (1/2): The bacterial system and prototype production.

The production of concrete for construction purposes is a major source of anthropogenic CO2 emissions. One promising avenue towards a more sustainable construction industry is to make use of naturally occurring mineral-microbe interactions, such as microbial-induced carbonate precipitation (MICP), to produce solid materials. In this paper, we present a new process where calcium carbonate in the form of powdered limestone is transformed to a binder material (termed BioZEment) through microbial dissolution and recrystallization. For the dissolution step, a suitable bacterial strain, closely related to Bacillus pumilus, was isolated from soil near a limestone quarry. We show that this strain produces organic acids from glucose, inducing the dissolution of calcium carbonate in an aqueous slurry of powdered limestone. In the second step, the dissolved limestone solution is used as the calcium source for MICP in sand packed syringe moulds. The amounts of acid produced and calcium carbonate dissolved are shown to depend on the amount of available oxygen as well as the degree of mixing. Precipitation is induced through the pH increase caused by the hydrolysis of urea, mediated by the enzyme urease, which is produced in situ by the bacterium Sporosarcina pasteurii DSM33. The degree of successful consolidation of sand by BioZEment was found to depend on both the amount of urea and the amount of glucose available in the dissolution reaction.

Agricultural and forestry trade drives large share of tropical deforestation emissions

Deforestation, the second largest source of anthropogenic greenhouse gas emissions, is largely driven by expanding forestry and agriculture. However, despite agricultural expansion being increasingly driven by foreign demand, the links between deforestation and foreign demand for agricultural commodities have only been partially mapped. Here we present a pan-tropical quantification of carbon emissions from deforestation associated with the expansion of agriculture and forest plantations, and trace embodied emissions through global supply chains to consumers. We find that in the period 2010–2014, expansion of agriculture and tree plantations into forests across the tropics was associated with net emissions of approximately 2.6 gigatonnes carbon dioxide per year. Cattle and oilseed products account for over half of these emissions. Europe and China are major importers, and for many developed countries, deforestation emissions embodied in imports rival or exceed emissions from domestic agriculture. Depending on the trade model used, 29–39% of deforestation-related emissions were driven by international trade. This is substantially higher than the share of fossil carbon emissions embodied in trade, indicating that efforts to reduce greenhouse gas emissions from land-use change need to consider the role of international demand in driving deforestation. Additionally, we find that deforestation emissions are similar to, or larger than, other emissions in the carbon footprint of key forest-risk commodities. Similarly, deforestation emissions constitute a substantial share (˜15%) of the total carbon footprint of food consumption in EU countries. This highlights the need for consumption-based accounts to include emissions from deforestation, and for the implementation of policy measures that cross these international supply-chains if deforestation emissions are to be effectively reduced.

Background Conditions Influence the Estimated Cloud Radiative Effects of Anthropogenic Aerosol Emissions From Different Source Regions

AbstractUsing the Community Earth System Model, with the Community Atmosphere Model version 5.3, we investigate the cloud radiative effects of anthropogenic aerosols emitted from different source regions and global shipping. We also analyze aerosol burdens, cloud condensation nuclei concentration, liquid water path, and ice water path. Due to transboundary transport and sublinearity in the response of clouds to aerosols, the cloud radiative effects of emissions from a given source region are influenced by emissions from other source regions. For example, the shortwave cloud radiative effect of shipping is −0.39 ± 0.03 W/m2 when other anthropogenic emissions sources are present (the “present‐day background” assumption) compared with −0.60 ± 0.03 W/m2 when other anthropogenic emissions sources are absent (the “natural background” assumption). In general, the cloud radiative effects are weaker if present‐day background conditions are assumed compared with if natural background conditions are assumed. Assumptions about background conditions should be carefully considered when investigating the climate impacts of aerosol emissions from a given source region.

Characterizing Spatiotemporal Dynamics of CH₄ Fluxes from Rice Paddies of Cold Region in Heilongjiang Province under Climate Change.

Paddy fields have become a major global anthropogenic CH4 emission source, and climate change affects CH4 emissions from paddy ecosystems by changing crop growth and the soil environment. It has been recognized that Heilongjiang Province has become an important source of CH4 emission due to its dramatically increased rice planting area, while less attention has been paid to characterize the effects of climate change on the spatiotemporal dynamics of CH4 fluxes. In this study, we used the calibrated and validated Long Ashton Research Station Weather Generator (LARS-WG) model and DeNitrification-DeComposition (DNDC) model to simulate historical and future CH4 fluxes under RCP 4.5 and RCP 8.5 of four global climate models (GCMs) in Heilongjiang Province. During 1960–2015, the average CH4 fluxes and climatic tendencies were 145.56 kg C/ha and 11.88 kg C/ha/(10a), respectively. Spatially, the CH4 fluxes showed a decreasing trend from west to east, and the climatic tendencies in the northern and western parts were higher. During 2021–2080, the annual average CH4 fluxes under RCP 4.5 and RCP 8.5 were predicted to be 213.46 kg C/ha and 252.19 kg C/ha, respectively, and their spatial distributions were similar to the historical distribution. The average climatic tendencies were 13.40 kg C/ha/(10a) and 29.86 kg C/ha/(10a), respectively, which decreased from west to east. The simulation scenario analysis showed that atmospheric CO2 concentration and temperature affected CH4 fluxes by changing soil organic carbon (SOC) content and plant biomass. This study indicated that a paddy ecosystem in a cold region is an important part of China’s greenhouse gas emission inventory in future scenarios.

Trends in the global cement industry and opportunities for long-term sustainable CCU potential for Power-to-X

In order to achieve targets set by the Paris Agreement and limit global average temperature increase to well below 2 °C above pre-industrial levels, an assessment and a low carbon transformation is needed for all types of human activities. Cement production is associated with high levels of CO2 emissions, with an average of 866 kg of CO2 emitted per ton of cement produced. This positions the cement industry as one of the main sources of anthropogenic greenhouse gas emissions accounting for about 5% of the total, right after the chemical industry and more relevant than the iron and steel industry. About 50% of the emissions are caused by burnt fuel, related transport and other inputs, which can be currently substituted by other measures. However, the CO2 emissions which originate from input limestone cannot be avoided. These process CO2 emissions present a potential for carbon capture and utilisation. This research proposes a global potential analysis of CCU as a possible solution for the CO2 emissions of cement production. Cement CCU may establish a substantial route to use CO2 for synthetic hydrocarbons production and thus contribute towards mitigating the non-substitutable CO2 content of the limestone-based raw material. The production of renewable electricity based synthetic hydrocarbon fuels by CO2 captured from cement plants, counts for a potential to produce between 3639 TWhth and 7355 TWhth of liquid hydrocarbons, or 6298 TWhth and 12723 TWhth of synthetic natural gas, or a mix of both at the expected global cement peak production in 2040.

Investigate the impact of local iron-steel industrial emission on atmospheric mercury concentration in Yangtze River Delta, China.

Mercury is a global neurotoxic pollutant, which can be globally transported and bioaccumulated in the food chain. Iron-steel production is one of the most significant sources of anthropogenic atmospheric mercury emission, while information on this source is scarce. Hourly gaseous elemental mercury (GEM) and particle bound mercury (PBM) were studied inside (IP) and at the boundary (BP) of a typical iron-steel plant in the Yangtze River Delta (YRD), China from September 2016 to August 2017. The GEM concentrations were 0.97-503.1 and 0.05-112.6ng/m3 at the IP and BP sites, respectively, while PBM concentrations were one to four orders of magnitude higher than urban and suburban ambient levels. Several lines of evidences indicated that PBM was mainly originated from the iron-steel manufacturing process, especially from sintering and coke-making processes in this iron-steel plant. However, a combined emission effect contributed to GEM variation. The receptor model of positive matrix factorization (PMF) showed that local direct emissions (coal combustion, industrial activity, vehicle exhaust, and secondary evaporation from polluted soil) contributed 51.3% of the total GEM concentration variation. Potential source contribution function (PSCF) and concentration weighted trajectory (CWT) models clearly showed that air masses moving from areas surrounding YRD had the highest concentrations of atmospheric mercury. These results provided evidence that iron-steel manufacturing emissions have a considerable effect on regional atmospheric mercury concentrations, especially PBM.

Evaluation of Practicable Subsurface CO2 Storage Capacity and Potential CO2 Transportation Networks, Onshore North America

Carbon Capture, Utilization and Storage (CCUS) is considered to be a potentially important technology for reducing the amount of carbon dioxide (CO2) released into the atmosphere from anthropogenic emission sources. With recent progress on capture technologies, attention is increasingly turning to the identification of key challenges associated with CO2 transportation and storage at the scale being considered for the CCUS industry. Decades of oil and gas production have provided experience in application of technologies required for CO2 transportation and storage, but the challenges unique to CO2 storage still need to be evaluated. This paper describes a scoping-level assessment of practicable subsurface geologic CO2 storage capacity and a potential Carbon Capture, Utilization, and Storage (CCUS) industry in the US and Canada, leveraging publically available data/information, publications, and methodologies. Likely subsurface CO2 storage sites and distribution of storage capacity relative to major anthropogenic sources are first characterized using a probabilistic methodology previously developed by the US Geologic Survey (USGS), which was modified to account for several practical factors affecting storage capacity. Major factors considered include 1) subsurface lateral accessibility restrictions imposed by faulting and/or stratigraphic pinch-outs, 2) the proportion of net storage-quality sand comprised of thin sands unlikely to be good injection candidates, 3) surface access restrictions, and 4) dynamic injectivity/storage efficiency considerations. Potential regional CCUS networks are then modeled using a transportation cost framework to map CO2 sources to storage sinks. The USGS assessment and most other existing assessments of storage capacity are based on the premise that all engineering approaches and hardware required to achieve the highest possible storage efficiency would be employed, and that injection rate and timeframe are not issues, with perhaps hundreds to thousands of years of injection permitted to achieve full storage efficiency. We explore the impact of dynamic injectivity considerations on practical storage efficiency by using reservoir simulation models to account for subsurface pressure limitations and the impact of permeability differences and lateral accessibility on CO2 injectability, and then use the results of the modeling to derive a debiting function that reduces the range of static storage capacity estimated by the USGS. Debiting functions accounting for lateral accessibility, thin sands, and surface access restrictions were also applied to obtain practicable storage estimates. Key conclusions from the study include: 1) Although the modified storage capacity estimates are lower than previously published estimates, the estimated subsurface storage capacity in the US onshore is sufficient to sustain a large-scale CO2 storage industry. We estimate that about 500 Gt of potential US subsurface storage capacity is potentially available (excluding federal offshore capacity) even after accounting for dynamic injectibility considerations, thin sands, surface and lateral access issues. Dynamic injectability factors had the largest impact on the reduction in estimated storage capacity. 2) Significant geographic misalignment exists between current high-volume CO2 emission sources and storage availability in North America. This could affect evolution of CO2 transportation networks with time. Detailed site-specific assessments of subsurface storage capacity are required for site selection and actual project implementation. These efforts could change some of the conclusions of this study. In particular, consideration of legacy wells and geomechanical factors such as induced seismicity, ground surface deformation, and fault activation may further reduce storage capacity relative to the estimates presented here. Nevertheless, the methodology described in this paper may be useful for initial assessment of CO2 storage capacity and matching of CO2 emission sources to storage sinks in geographic locations other than those considered in this study.

Current state of atmospheric air pollution in Ukraine based on Sentinel-5P satellite data

Introduction. Industrial development and increasing traffic emissions cause air quality problems. The most accurate for air pollution analysis are ground-based data; however, it is very limited in space. Modelling could solve this problem, but huge amount of input information and limits of computational power make it difficult to analyze big territories with high resolution. Sentinel-5P satellite with TROPOMI instrument nowadays gives opportunities to monitor the air pollution with good spatial resolution. The purpose of the study is to analyse nitrogen dioxide, sulfur dioxide, carbon monoxide and formaldehyde spatial and temporal distribution over Ukraine and Black Sea and Azov Sea. Methods and raw data. There were selected Sentinel-5P data of NO2, SO2, CO and HCHO for the period from first data release in 2018 to June, 2019. Data processing implemented in Google Earth Engine using JavaScript programming in The Earth Engine Code Editor. Results and discussion. Joint analysis of NO2 tropospheric, stratospheric and total columns showed the prevailing of tropospheric NO2 content and therefore crucial role of anthropogenic emission sources. While background NO2 total column varies from 4·10-5 mol/m2 to 7·10-5 mol/m2, in the most polluted cities content exceeds 1·10-4 mol/m2. The highest values are observed in Kyiv and industrial cities in Donbas region. Some of them are situated in the area of Joint Forces Operation outside the demarcation line. Sentinel-5P data catch the large emissions from the local industries; however, no official confirmations about production volume are available. NO2 dispersion increase during winter with the values range from 1·10-5 mol/m2 to 3·10-5 mol/m2 over clean territories and 8·10-5 mol/m2 to 1·10-3 mol/m2 in industrial cities. Seasonal maximal observed during warm period in unpolluted regions and during winter in the cities. Cold seasonal NO2 content outbreaks in the mountains are the result of its transportation from industrial cities. Spatial distribution of CO total column over Ukraine is rather homogeneous because of CO lifetime in the atmosphere up to several months. It could be transported on the long distances, which makes identification of polluted regions difficult. However, several cities with maximal average values of more than 0.037mol/m2 prove the existence of extreme anthropogenic emissions. Overall background CO contents vary within 0.033–0.035 mol/m2. Coastal regions of the Black Sea and Azov Sea are more polluted by CO compared to the mainland, which could be the consequences of ships emissions. Temporal analysis of CO total column found 4 powerful emissions: three of them are anthropogenic in industrial cities and one is natural, connected with forest fires in Belarus and northern part of Rivne region in April, 2019. There is one location with huge SO2 emission in Ukraine, observed in Novyi Svit (Donetsk region) outside the demarcation line of Joint Forces Operation, which corresponds to Starobeshivska thermal power station. In general, higher SO2 contents are observed over Donetsk, Zaporizhia and Dnipro regions; also over the Black Sea and Azov Sea. For HCHO spatial distribution minimal values are typical for the Carpathians. It is well seen that SO2 content are higher in the Southern part of Ukraine than in the Western part. The research finds regularities in spatial distribution of pollutants over the sea area. During cold season higher concentrations could be observed over the main merchant vessels tracks in the Black Sea. In summer months, which coincide with the main tourist season, most polluted are shoreline area because of emissions from cabotage and fishing vessels. The study updates information about most polluted cities in Ukraine, especially in the regions with absence of ground-based measurements. Some of them are mentioned for the first time among other research. Air quality analysis in many industrial cities significantly changed over the last two years. It shows difficulties of long-term pollution forecast and scenarios based on historical data and observed trends. It is recommended to use ensemble modelling for this purpose with scenarios of emission reduction, increasing and temporal stability. Sentinel-5P data confirm the conclusions of previous research about dependence of NO2 annual cycle and seasonality phases shift from the level of anthropogenic load. Prospects for further research. Sentinel-5P spatial resolution expands the horizons for air pollution research. The most relevant are monitoring of short-term anthropogenic and natural emissions, pollutants’ seasonality changes in different macroclimatic conditions, research of ships emissions in Black Sea and Azov Sea, combination of satellite air pollution data with methods of “artificial intelligence” for individual emissions detection.

New insights in sources of the sub-micrometre aerosol at Mt. Zeppelin observatory (Spitsbergen) in the year 2015

In order to evaluate the potential impact of the Arctic anthropogenic emission sources it is essential to understand better the natural aerosol sources of the inner Arctic and the atmospheric processing of the aerosols during their transport in the Arctic atmosphere. A 1-year time series of chemically specific measurements of the sub-micrometre aerosol during 2015 has been taken at the Mt. Zeppelin observatory in the European Arctic. A source apportionment study combined measured molecular tracers as source markers, positive matrix factorization, analysis of the potential source distribution and auxiliary information from satellite data and ground-based observations. The annual average sub-micrometre mass was apportioned to regional background secondary sulphate (56%), sea spray (17%), biomass burning (15%), secondary nitrate (5.8%), secondary marine biogenic (4.5%), mixed combustion (1.6%), and two types of marine gel sources (together 0.7%). Secondary nitrate aerosol mainly contributed towards the end of summer and during autumn. During spring and summer, the secondary marine biogenic factor reached a contribution of up to 50% in some samples. The most likely origin of the mixed combustion source is due to oil and gas extraction activities in Eastern Siberia. The two marine polymer gel sources predominantly occurred in autumn and winter. The small contribution of the marine gel sources at Mt. Zeppelin observatory in summer as opposed to regions closer to the North Pole is attributed to differences in ocean biology, vertical distribution of phytoplankton, and the earlier start of the summer season.

Occurrence and fate of methane leakage from cut and buried abandoned gas wells in the Netherlands

Methane leakage caused by well integrity failure was assessed at 28 abandoned gas wells and 1 oil well in the Netherlands, which have been plugged, cut and buried to below the ground surface (≥3 mbgl). At each location, methane concentrations were thoroughly scanned at the surface. A static chamber setup was used to measure methane flow rates from the surface as well as from 1 m deep holes drilled using a hand auger. An anomalously high flow rate from 1 m depth combined with isotopic confirmation of a thermogenic origin revealed ongoing leakage at 1 of the 29 wells (3.4%), that had gone undetected by surficial measurements. Gas fluxes at the other sites were due to shallow production of biogenic methane. Detailed investigation at the leaking well (MON-02), consisting of 28 flux measurements conducted in a 2 × 2 m grid from holes drilled to 1 and 2 m depth, showed that flux magnitude was spatially heterogeneous and consistently larger at 2 m depth compared to 1 m. Isotopic evidence revealed oxidation accounted for roughly 25% of the decrease in flux towards the surface. The estimated total flux from the well (443 g CH4 hr−1) was calculated by extrapolation of the individual flow rate measurements at 2 m depth and should be considered an indicative value as the validity of the estimate using our approach requires confirmation by modelling and/or experimental studies. Together, our findings show that total methane emissions from leaking gas wells in the Netherlands are likely negligible compared to other sources of anthropogenic methane emissions (e.g. <1% of emissions from the Dutch energy sector). Furthermore, subsurface measurements greatly improve the likelihood of detecting leakage at buried abandoned wells and are therefore essential to accurately assess their greenhouse gas emissions and explosion hazards.

Limited potential of harvest index improvement to reduce methane emissions from rice paddies.

Rice is a staple food for nearly half of the world's population, but rice paddies constitute a major source of anthropogenic CH4 emissions. Root exudates from growing rice plants are an important substrate for methane-producing microorganisms. Therefore, breeding efforts optimizing rice plant photosynthate allocation to grains, i.e., increasing harvest index (HI), are widely expected to reduce CH4 emissions with higher yield. Here we show, by combining a series of experiments, meta-analyses and an expert survey, that the potential of CH4 mitigation from rice paddies through HI improvement is in fact small. Whereas HI improvement reduced CH4 emissions under continuously flooded (CF) irrigation, it did not affect CH4 emissions in systems with intermittent irrigation (II). We estimate that future plant breeding efforts aimed at HI improvement to the theoretical maximum value will reduce CH4 emissions in CF systems by 4.4%. However, CF systems currently make up only a small fraction of the total rice growing area (i.e., 27% of the Chinese rice paddy area). Thus, to achieve substantial CH4 mitigation from rice agriculture, alternative plant breeding strategies may be needed, along with alternative management.

Global CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; emissions from cement production, 1928–2017

Abstract. Global production of cement has grown very rapidly in recent years, and after fossil fuels and land-use change, it is the third-largest source of anthropogenic emissions of carbon dioxide. The availability of the required data for estimating emissions from global cement production is poor, and it has been recognised that some global estimates are significantly inflated. Here we assemble a large variety of available datasets, prioritising official data and emission factors, including estimates submitted to the UNFCCC plus new estimates for China and India, to present a new analysis of global process emissions from cement production. We show that global process emissions in 2017 were 1.48±0.20 Gt CO2, equivalent to about 4 % of emissions from fossil fuels. Cumulative emissions from 1928 to 2017 were 36.9±2.3 Gt CO2, 70 % of which have occurred since 1990. Emissions in 2016 were 28 % lower than those recently reported by the Global Carbon Project. The data associated with this article can be found at https://doi.org/10.5281/zenodo.831454.

The importance of cylinder passivation for preparation and long-term stability of multicomponent monoterpene primary reference materials

Abstract. Monoterpenes play an important role in atmospheric chemistry due to their large anthropogenic and biogenic emission sources and high chemical reactivity. As a consequence, measurements are required to assess how changes in emissions of monoterpenes impact air quality. Accurate and comparable measurements of monoterpenes in indoor and outdoor environments require gaseous primary reference materials (PRMs) that are traceable to the international system of units (SI). PRMs of monoterpenes are challenging to produce due to the high chemical reactivity and low vapour pressures of monoterpenes and also their propensity to convert into other compounds, including other terpenes. In this paper, the long-term stability of gravimetrically prepared static monoterpene PRMs produced in differently passivated cylinders, including sampling canisters, was assessed. We demonstrate that static PRMs of multiple monoterpenes can be prepared and used as a suitable long-term standard. For the first time the effect of cylinder pressure and decanting from one cylinder to another on the chemical composition and amount fraction of monoterpenes was also studied. Gravimetrically prepared PRMs of limonene in high pressure cylinders were compared to a novel portable dynamic reference gas generator based on dilution of pure limonene vapour emitted from a permeation tube.

Spatial and temporal distribution of total mercury in atmospheric wet precipitation at four sites from the Nepal-Himalayas

The studies on global pollutant mercury (Hg), which is of public concern due to its high toxicity and capacity to long-range transport via atmospheric circulation, is poorly characterized in wet deposition over the Nepal-Himalayas region. Therefore, in order to understand the concentration levels, spatial distribution and seasonal variation of total Hg, 333 precipitation samples were collected from south to north: Kathmandu (1314 m a.s.l.), Dhunche (2065 m a.s.l.), Dimsa (3078 m a.s.l.) and Gosainkunda (4417 m a.s.l.) characterized as urban, rural, remote forest and remote alpine sites, respectively, for over one-year period. The highest Hg concentration was found in Kathmandu comparable to the urban sites worldwide, and significantly lower concentrations at other three sites demonstrated similar levels as in rural and remote alpine sites worldwide. Higher wet deposition fluxes of 34.91 and 15.89 μg m−2 year−1 were found in Kathmandu and Dhunche respectively, due to higher precipitation amount. Clear and distinct seasonal differences were observed with higher concentrations in non-monsoon and lower values in monsoon periods due to less scavenging and high pollutant concentration loadings during the dry period. The positive correlation of Hg flux and precipitation amount with Hg concentration suggested that both precipitation amount and Hg concentration plays a vital role in Hg deposition in the central Himalayan region. Enrichment factor (EFHg) indicated that the anthropogenic emission sources play a significant role for Hg enrichment and a high ratio of EFmonsoon to EFnon-monsoon (>2.18) suggested that the anthropogenic atmospheric mercury could likely be long-range transported from south Asian regions to the Himalayas during the monsoon season. In addition, our results showed that the major ionic compositions (e.g., SO42−, NO3−, NH4+, K+, Ca2+) could influence Hg concentration in wet precipitation. The anthropogenic sources of Hg such as biomass and fossil fuel combustion, crustal aerosols may contribute to the Hg concentration in wet precipitation over the central Himalayas.

The importance of small artificial water bodies as sources of methane emissions in Queensland, Australia

Abstract. Emissions from flooded land represent a direct source of anthropogenic greenhouse gas (GHG) emissions. Methane emissions from large, artificial water bodies have previously been considered, with numerous studies assessing emission rates and relatively simple procedures available to determine their surface area and generate upscaled emissions estimates. In contrast, the role of small artificial water bodies (ponds) is very poorly quantified, and estimation of emissions is constrained both by a lack of data on their spatial extent and a scarcity of direct flux measurements. In this study, we quantified the total surface area of water bodies &lt; 105 m2 across Queensland, Australia, and emission rates from a variety of water body types and size classes. We found that the omission of small ponds from current official land use data has led to an underestimate of total flooded land area by 24 %, of small artificial water body surface area by 57 % and of the total number of artificial water bodies by 1 order of magnitude. All studied ponds were significant hotspots of methane production, dominated by ebullition (bubble) emissions. Two scaling approaches were developed with one based on pond primary use (stock watering, irrigation and urban lakes) and the other using size class. Both approaches indicated that ponds in Queensland alone emit over 1.6 Mt CO2 eq. yr−1, equivalent to 10 % of the state's entire land use, land use change and forestry sector emissions. With limited data from other regions suggesting similarly large numbers of ponds, high emissions per unit area and under-reporting of spatial extent, we conclude that small artificial water bodies may be a globally important missing source of anthropogenic greenhouse gas emissions.

Impacts of global carbon pricing on international trade, modal choice and emissions from international transport

Transportation is one of the significant sources of global anthropogenic emissions, generating about 14% of global Greenhouse Gas Emissions (GHG) with the largest contribution from ground transportation followed by air and water transport. However, international climate agreements such as the Kyoto Protocol or Paris Agreement focused mostly on the regulation of production emissions without considering transport emissions in policy regulations. In this paper I analyze the effects of global carbon pricing on international trade and modal choice in the transportation of goods between countries, and resulting changes in international transport emissions. For this purpose I modify the Energy-environmental version of the Global Trade Analysis Project (GTAP-E) model to allow for substitution among different modes of transport.I find that a global GHG tax increases the competitiveness of transport services exports from the most developed countries which exhibit relatively low economic emissions intensities, while having a negative effect of services exports from most developing regions, which have relatively higher emissions rates per dollar of transport services. The findings also indicate that when international transport emissions and modal substitution are considered in global emissions regulation policies there is significant impact on the expected reduction in global emissions and global warming.