Search Results (45)

The global energy sector is aiming to substantially reduce CO₂ emissions to meet the UN climate goals. Among the proposed strategies, underground storage solutions such as radioactive disposal, CO₂, NH₃, and underground H₂ storage (UHS) have emerged as promising options for mitigating anthropogenic emissions. These approaches require rigorous research and development (R&D), often involving laboratory-scale experiments to establish their feasibility before being scaled up to pilot plant operations. Microorganisms, which are ubiquitous in laboratory environments, can significantly influence geochemical reactions under variable experimental conditions of porous media and a salt cavern. We have selected a consortium composed of Bacillus sp., Enterobacter sp., and Cronobacter sp. bacteria, which are typically present in the laboratory environment. These microorganisms can contaminate the rock sample and develop experimental artifacts in UHS experiments. Hence, it is pivotal to sterilize the rock prior to conduct experimental research related to effects of microorganisms in the porous media and the salt cavern for the investigation of UHS. This study investigated the efficacy of various disinfection and sterilization methods, including ultraviolet irradiation, autoclaving, oven heating, ethanol treatments, and gamma irradiation, in removing the microorganisms from silica sand. Additionally, the consideration of their effects on mineral properties are reviewed. A total of 567 vials, each filled with 9 mL of acid-producing bacteria (APB) media were used to test killing efficacy of the cleaning methods. We conducted serial dilutions up to 10⁻⁸ and repeated them three times to determine whether any deviation occurred. Our findings revealed that gamma irradiation and autoclaving were the most effective techniques for eradicating microbial contaminants, achieving sterilization without significantly altering the mineral characteristics. These findings underscore the necessity of robust cleaning protocols in hydrogeochemical research to ensure reliable, reproducible data, particularly in future studies where microbial contamination could induce artifacts in laboratory research. Full article

Reservoirs are hotspots for emissions of the greenhouse gas nitrous oxide; however, the nitrite cycling processes associated with nitrous oxide production therein remain poorly understood, limiting a better assessment of the potential for reservoirs to emit nitrous oxide. Accordingly, this study presents the application of the natural abundance isotope technique combined with a geochemical model to elucidate the nitrite cycling in the freshwater aquaculture and non-aquaculture zones of a large artificial reservoir in eastern China. We employed nitrite dual isotopes to identify nitrite transformation processes. Additionally, a steady-state model was used to estimate the rates of these processes as well as the residence time of nitrite. Our findings indicate that nitrite production in this reservoir may be primarily driven by ammonia oxidation. However, the pathways of nitrite removal differ notably between the aquaculture and non-aquaculture zones, suggesting a significant impact of the aquaculture activities. The steady-state model calculations revealed that nitrification may be more pronounced in the aquaculture zones compared to the non-aquaculture zones, which may be related to the altered balance of competition for substrates between phytoplankton and microbes induced by aquaculture activities. Moreover, we observed a latitude-dependent increase in the significance of nitrite oxidation in natural environments, highlighting potential implications for regional and global nitrogen cycling. Our study highlights the complexity of the nitrite cycle and emphasizes the roles of both natural and anthropogenic factors in shaping nitrogen dynamics within freshwater reservoirs. This understanding contributes to a more accurate assessment of the greenhouse gas emission potential of reservoirs, offering valuable implications for the adoption of sustainable aquaculture practices to mitigate climate impacts and support global sustainable development goals. Full article

Gaseous air pollutants emitted primarily by anthropogenic sources form secondary products through photochemical reactions, complicating the regulatory analysis of anthropogenic emissions in the atmosphere. We used an environmental chassis dynamometer and a photochemical smog chamber to conduct a parameter sensitivity experiment to investigate the formation of secondary products from a gasoline passenger car. To simulate the mitigation of ammonia emissions from gasoline vehicle exhausts assuming future emission controls and to allow photochemical oxidation and aging of the vehicle exhaust, ammonia was selectively removed by a series of five denuders installed between the vehicle and photochemical smog chamber. Overall, there were no differences in the formation of secondary organic aerosols and ozone with or without ammonia mitigation. However, the potential for ammonium nitrate particle formation was significantly reduced with ammonia mitigation. In addition, ammonia mitigation resulted in increased aerosol acidity due to nitric acid in the gas phase not being neutralized by ammonia and condensing onto the liquid particle phase, indicating a potentially important secondary effect associated with ammonia mitigation. Thus, we provide new insights into the effects of ammonia mitigation on secondary emissions from gasoline vehicle exhaust and into a potentially useful experimental approach for determining primary and secondary emissions. Full article

Carbon sequestration by photosynthetic organisms is the principal mechanism for the absorption of atmospheric CO₂. Since the 1950s, however, the global carbon cycle has been distorted as increased anthropogenic CO₂ emissions have greatly outstripped rates of carbon sequestration, with a 50% increase in atmospheric CO₂ levels in less than a century, leading to perturbation of global climate systems and threatening food production and social stability. In order to address the current imbalance in CO₂ flux, it is important to both reduce net emissions and promote sequestration. To address the latter issue, we need to better understand the roles of systems, such as natural forests, coastal wetlands, and tropical croplands, in carbon sequestration and devise strategies to facilitate net CO₂ uptake. Carbon sequestration by tropical trees and crops already removes in excess of 1000 million tonnes of atmospheric CO₂ annually but is threatened by anthropogenic activities such as deforestation and the drainage of carbon-rich peatland. Improvements in carbon sequestration can be achieved by policies such as growing tropical crops as part of agroforestry systems, enforcing limitations on deforestation and the use of peatland, and auditing the carbon impact of major cropping systems in order to focus on those crops that deliver both high yields and carbon efficiency. As an initial step in this process, a detailed case study is presented on the tropical tree crop, the African oil palm, Elaeis guineensis. This analysis includes a comparison of the carbon sequestration potential of oil palm with that of tropical forests and other oil crops, the biomass sequestration potential of oil palm and current and future strategies aimed at achieving net-zero carbon targets for oil palm and related crops. Full article

Greenhouse gases (GHGs) like nitrous oxide (N₂O), carbon dioxide (CO₂), and methane (CH₄) are both emitted and removed by soils. Accurate worldwide allocations of carbon budget are essential for land use planning, global climate change, and climate-related research. Precise measurements, drivers, and mitigation strategies are necessary, given agricultural soil’s significant potential storage and emission capacities. Different agricultural management practices cause greenhouse gas (GHG) emissions into the atmosphere and contribute to anthropogenic emissions. Agricultural soils can generate 70% of the world’s manmade N₂O emissions and also behave as a CO₂ sink and a source of organic carbon and as producers and consumers of CH₄. When it comes to agronomic management, the source and sink of all these GHGs are distinct. Therefore, several approaches to measuring GHG emissions from agricultural soils are available and can be categorized into chamber systems and remote sensing approaches. Sustainable agriculture stands out as a viable and transformative approach to increase agricultural efficiency while addressing the challenge of GHG emissions. Incorporating advanced technologies, precise data analytics, and site-specific management practices can offer a pathway to mitigate GHG emissions, thereby reducing the global warming potential (GWP). Therefore, this review paper focuses solely on the drivers influencing and involving soil emissions and on quantification approaches for GHG emissions. In addition, mitigation practices aimed at optimizing GHG emissions from agricultural soils are highlighted. Full article

In the global carbon cycle, atmospheric carbon emissions, both ‘natural’ and anthropogenic, are balanced by carbon uptake (i.e., sequestration) that mostly occurs via photosynthesis, plus a much smaller proportion via geological processes. Since the formation of the Earth about 4.54 billion years ago, the ratio between emitted and sequestered carbon has varied considerably, with atmospheric CO₂ levels ranging from 100,000 ppm to a mere 100 ppm. Over this time, a huge amount of carbon has been sequestered due to photosynthesis and essentially removed from the cycle, being buried as fossil deposits of coal, oil, and gas. Relatively low atmospheric CO₂ levels were the norm for the past 10 million years, and during the past million years, they averaged about 220 ppm. More recently, the Holocene epoch, starting ~11,700 years ago, has been a period of unusual climatic stability with relatively warm, moist conditions and low atmospheric CO₂ levels of between 260 and 280 ppm. During the Holocene, stable conditions facilitated a social revolution with the domestication of crops and livestock, leading to urbanisation and the development of complex technologies. As part of the latter process, immense quantities of sequestered fossil carbon have recently been used as energy sources, resulting in a particularly rapid increase in CO₂ emissions after 1950 CE to the current value of 424 ppm, with further rises to >800 ppm predicted by 2100. This is already perturbing the previously stable Holocene climate and threatening future food production and social stability. Today, the global carbon cycle has been shifted such that carbon sequestration is no longer keeping up with recent anthropogenic emissions. In order to address this imbalance, it is important to understand the roles of potential biological carbon sequestration systems and to devise strategies to facilitate net CO₂ uptake; for example, via changes in the patterns of land use, such as afforestation, preventing deforestation, and facilitating agriculture–agroforestry transitions. Full article

Particulate-bound mercury (PBM) has a large dry-deposition rate and removal coefficient, both of which import mercury into terrestrial and marine ecosystems, causing global environmental problems. In order to illustrate the concentration characteristics, main sources, and health risk of PBM in the atmospheric environment during the spring dust storm period in Xi’an in 2022, PM_2.5 samples were collected in Xi’an in March 2022. The concentration of PBM and the PM_2.5 composition, including water-soluble ions and elements, were analyzed. The input of dust caused a significant increase in the concentration of PBM, Ca²⁺, Na⁺, Mg²⁺, SO₄²⁻, and metal elements in the aerosol. The research results revealed that the dust had a strong enrichment influence on the atmospheric PBM in Xi’an. Anthropogenic mercury emissions and long-distance migration in the sand source area promote the rise in PBM concentration and should be included in the mercury inventory. The values of the risk index for a certain metal (E_rⁱ) (572.78–1653.33) and the geo-accumulation index (Igeo) (2.47–4.78) are calculated during this study, showing that atmospheric PBM has a strong pollution level with respect to the ecological environment and that Hg mainly comes from anthropogenic mercury emissions. The non-carcinogenic health risk of atmospheric PBM in children (8.48 × 10⁻²) is greater than that in adults (1.01 × 10⁻²). The results show that we need to pay more attention to children’s health in the process of atmospheric mercury pollution control. This study discusses the distribution characteristics of PBM during spring sandstorms and the effects of atmospheric mercury on residents’ health, providing a basis for studying the sustainable development of environmental health and formulating effective strategies for mercury emission control. Full article

Due to anthropogenic emissions, the global CO₂ concentration increases at a rate of approximately 2 ppm per year. With over 130 countries and regions committing to carbon neutrality goals and continuously reducing anthropogenic CO₂ emissions, understanding how atmospheric CO₂ concentrations will change globally and in other regions has become an intriguing question. Examining different regions’ efforts to reduce anthropogenic CO₂ emissions through atmospheric CO₂ observations is also meaningful. We used prior and posterior fluxes to drive the TM5 model. The posterior fluxes were based on the China Carbon Monitoring, Verification and Support System for Global (CCMVS-G), which assimilated the atmospheric CO₂ concentration data from ground-based observation and satellite observation. We found that the CO₂ concentration obtained using the posterior fluxes was more in line with the actual situation. Then, we presented some experiments to estimate how global and regional CO₂ concentrations would change if certain key regions and the whole world achieved net zero emissions of anthropogenic CO₂. After removing carbon fluxes from China, North America, and Europe, global CO₂ concentrations decreased by around 0.58 ppm, 0.22 ppm, and 0.10 ppm, respectively. The most significant decrease occurred in the regions where fluxes were removed, followed by other areas at the same latitude affected by westerly winds. This indicates that fossil fuel flux is the main factor affecting CO₂ concentrations, and that meteorological-driven transportation also significantly impacts CO₂ concentrations. Most importantly, using this method, it is possible to quantitatively estimate the impact of achieving carbon neutrality in one region on CO₂ concentrations in local regions as well as globally. Full article

In order to achieve global climate goals, it is necessary to estimate greenhouse gas (GHG) fluxes from ecosystems. To obtain a comprehensive assessment of CO₂, CH₄, and N₂O natural fluxes for the Russian Federation, we used the “bottom-up” method and updated estimates for forest ecosystems based on State Forest Inventory data and satellite monitoring of forest disturbances. For grassland ecosystems, it was based on the correct distribution of areas between steppe and non-steppe zones. The estimated net uptake of natural ecosystems in Russia was 1.1 ± 1.8 billion tons of CO₂-eq./year. The study shows that if only CO₂ is taken into account, the net absorption of terrestrial ecosystems in Russia corresponds to more than −2.5 billion tons of CO₂ (35% of forests’ contribution). However, given the emissions of non-CO₂ GHGs, total net absorption in Russia’s natural ecosystems is reduced to about −1 billion tons of CO₂-eq (with the forests’ contribution increasing to 80%). With regard to anthropogenic fluxes, the overall balance of GHGs in Russia corresponds to net emissions of 1 billion tons of CO₂-eq/year into the atmosphere. To improve reporting under the Paris Agreement, countries should aim to include only anthropogenic (“manageable”) GHG fluxes on managed land. Full article

The prevalent high-energy, high-pollution and high-emission economic model has led to significant air pollution challenges in recent years. The industrial sector in the Beijing–Tianjin–Hebei (BTH) region is a notable source of atmospheric pollutants, with industrial heat sources (IHSs) being primary contributors to this pollution. Effectively managing emissions from these sources is pivotal for achieving air pollution control goals in the region. A new three-stage model using multi-source long-term data was proposed to estimate atmospheric, delicate particulate matter (PM_2.5) concentrations caused by IHS. In the first stage, a region-growing algorithm was used to identify the IHS radiation areas. In the second and third stages, based on a seasonal trend decomposition procedure based on Loess (STL), multiple linear regression, and U-convLSTM models, IHS-related PM_2.5 concentrations caused by meteorological and anthropogenic conditions were removed using long-term data from 2012 to 2021. Finally, this study analyzed the spatial and temporal variations in IHS-related PM_2.5 concentrations in the BTH region. The findings reveal that PM_2.5 concentrations in IHS radiation areas were higher than in background areas, with approximately 33.16% attributable to IHS activities. A decreasing trend in IHS-related PM_2.5 concentrations was observed. Seasonal and spatial analyses indicated higher concentrations in the industrially dense southern region, particularly during autumn and winter. Moreover, a case study in Handan’s She County demonstrated dynamic fluctuations in IHS-related PM_2.5 concentrations, with notable reductions during periods of industrial inactivity. Our results aligned closely with previous studies and actual IHS operations, showing strong positive correlations with related industrial indices. This study’s outcomes are theoretically and practically significant for understanding and addressing the regional air quality caused by IHSs, contributing positively to regional environmental quality improvement and sustainable industrial development. Full article

The shipping industry is the most fuel-efficient means of transporting goods, carrying more than 90% of the global freight task. Ships generally use low quality fuel to reduce costs and, as a result, the sulfur content in the exhaust gas stream is high. Emissions of sulfur oxides (SO_x) and nitrogen oxides (NO_x) from ships represent about 13% and 12%, respectively, of the global anthropogenic SO_x and NO_x emissions. In total, 95% of the total maritime NOx emissions are NO (nitric oxide) and 5% are NO₂ (nitrogen dioxide). The present work focuses on the development and pilot operation of an advanced novel Selective Catalytic Reduction of NO_x with H₂ (H₂-SCR) technology for the elimination of Nitrogen Oxides (NO_x) emitted from ship exhaust gases. For the proper operation of the novel H₂-SCR de-NO_x unit, two additional conventional technologies were employed for the removal of SO₂ and Particulate Matter (PM). In particular, the proposed novel H₂-SCR de-NO_x technology was combined with a Sea Water Absorption (SWA) unit and an oxidative catalytic system. A pilot unit has been successfully designed, assembled and implemented on a cruise ship for the abovementioned purposes. This effort is considered to be pioneering and is here attempted for the first time worldwide. It was proven, for the first time ever, that the Selective Catalytic Reduction of NO_x with the use of H₂ as a reducing agent in combination with a suitable catalyst can be considered a suitable NO_x-pollution control technology for ships. In particular, it was found that more than 80% of NO_x (to N₂), 99.8% of SO₂ and 72% of PM can be reduced by using the present combined SWA and H₂-SCR technologies. Full article

In the context of climate change, the questions of the sustainability of peat soil use are particularly relevant. The evaluation of changes in the properties of soils (including histosols) using chemical methods is expensive, thus, their application possibilities are limited. Analyzing the morphology of histosol profiles would provide effective spatial analysis opportunities for assessing the extent of their anthropogenic transformation and impact on climate change. The key diagnostic horizons and their sequences for the identification of the risk group are the main results of the study. The analysis included 12 soil profiles, whose morphological structure was characterized using the WRB 2022 system of master symbols and suffixes for soil profile horizon descriptions. The analyzed profiles were excavated in forested (relatively natural), agricultural (agrogenized) and peat mining (technogenized) areas. The insights of this article in the discussion are based on the chemical analyses (pH KCl, N, P and K, soil organic carbon, dissolved organic carbon, mobile humus substance, humic and fulvo acids, C:N ratio and humification degree) of three histosol profiles. The main discussion is based on the results of the morphological analysis of the profiles. The results of this research allowed for the identification of a different structure of the histosol profile. The upper part of the histosol profile, which consists of O–H(a,e,i) horizons, indicates its naturalness. The murshic horizon (Hap) is the classic top horizon of the agricultural histosol profile, which is most affected by mineralization. The technogenized histosols have a partially destroyed profile, which is represented by the Ahτ/Haτ or only Haτ horizons at the top. The morphology of the histosol profile and the identification of the relevant horizons (Hap, Haτ and Ahτ) indicate its risks and presuppose a usage optimization solution. The most dangerous in the context of sustainable land use principles and climate change is the murshic horizon (Hap), which is uncovered after removing the horizon O. The risks of sustainable use of histosol are caused by measures that promote its microbiological activity, which is the maintenance of a drained state and cultivation. In the context of GHG emissions and sustainable use, the most favorable means would be the formation of the horizon O by applying perennial plants. Rewetting should be applied to those histosols whose removal from the agricultural or mining balance would provide maximum ecological benefits. Full article

The growing population, intensified anthropogenic pressures and climate variability have increased the demands on available water resources, and water reuse has become a high priority, particularly in areas of the world suffering from water stress. The main objectives of this review paper are to consider and identify the potential opportunities and challenges in the implementation of water reuse schemes worldwide by considering and analyzing different fields of interest in water reuse, the current and future global drivers of water reuse policies, the existing advances in treatment and reuse technologies promising elimination of environmental footprint and human health risk, an analysis of the trends in potable and non-potable reuse, and the development of quality criteria and issues related to transition circular economy. Moreover, the major knowledge gaps in critical issues on different domains of water reuse schemes are discussed. For this study, a thorough analysis of the current literature was conducted, using research and review articles, technical reports, specific national (and EU) proposals, guidance documents, and legislative initiatives and actions, as well as any validly disseminated findings by scientists around the world in the wider scientific area of (alternative) water resources, water supply, water management, sustainable development, and protection of public health. Water reuse practices are expected to increase in the future, mainly in developed countries and climate-vulnerable areas of the planet. Current advances in wastewater treatment and water reuse technologies can provide the opportunity for the foul exploitation of alternative water resources, increasing the potential of potable and non-potable water reuse systems worldwide, relying on pollutant/contaminant elimination, and improving economic and energy performances. Moreover, paradigmatic and technological switches based on an improved understanding of the relationships between the water cycle and the Water–Energy–Food (WEF) Nexus will increase the perspective of water reuse schemes. The benefits of the recovery of nutrients through sewage wastewater treatment are also highlighted, arising from reduced costs associated with their sheer removal and the supplement of fertilizers to the WEF Nexus. On the other hand, reduced nutrient removal may promote agricultural or landscape reuse practices, contributing to less energy consumption and reducing GHGs emissions. Regarding the management of water use schemes, a holistic approach (integrated management) is proposed, incorporating regulatory actions, actions increasing public awareness, interconnection among actors/stakeholders, and efficient control and monitoring. The establishment of quality criteria is paramount to preventing undesirable impacts on humans and the environment. The study considers the “one water” concept, which means equal water quality criteria independent of the origin of water, and instead differentiates among different types of water reuse as a means to facilitate implementation and management of potable and non-potable water reuse. Finally, it highlights the need to understand the impacts of water reuse systems on ecosystem services (ESs) and the consequences of achieving the global sustainable development goals (SDGs). Full article

The cement industry is one of the primary sources producing anthropogenic CO₂ emissions. The significant increase in the demand for cement in years has significantly contributed to the increase in carbon emissions. Among numerous CO₂ treatment technologies, calcium looping (CaL) is a practical approach to mitigating CO₂ emissions. This paper used calcium looping (CaL) to capture CO₂ from flue gas in a cement pre-calciner kiln system. The raw material exiting the lowest stage of the preheater is used as a calcium-based adsorbent, and the carbonation reactor is built between the tertiary and secondary preheaters, using the high-temperature flue gas exiting the tertiary preheater to provide heat for the reaction. The CFD (Computational Fluid Dynamics) simulation technology was used to evaluate the rationality of the carbonation reactor and the key factors affecting the carbon removal efficiency of the carbonation reactor. The results indicate that the velocity and pressure fields of the carbonation reactor conform to the general operating rules and are reasonable. The optimal operating speed of particles in the carbonation reactor is 15 m/s, with a separation efficiency of particles of 92.5%, ensuring the smooth discharge of reaction products. The factor analysis of the carbonation reactor shows that when the temperature is 911 K, the mass flow rate of CaO is 2.07 kg/s, and the volume fraction of CO₂ is 0.28, the carbonation reaction reaches a chemical equilibrium state, and the carbon removal efficiency is 90%. It should be noted that this carbon removal efficiency is the optimal carbon removal efficiency based on a combination of economic factors. In addition, the influencing factors show a precise sequence: CO₂ volume fraction > CaO addition amount > temperature. Finally, we investigated the impact of the addition of the carbonation reactor on the preheater system. The results show that adding the carbonation reactor causes an increase in the flue gas velocity at the outlet of the preheater and a decrease in pressure, reducing the separation efficiency. Although the separation efficiency decreases slightly, the impact on the pre-calciner system is minimal. Full article

Mercury is considered one of the most harmful ecotoxic elements. A main source of its anthropogenic emissions is fuel combustion. For fuels with a high mercury content, costly methods are required to remove mercury from the flue gases. The solution to this problem is to remove mercury from the fuel before combustion. This can be achieved by a mild pyrolysis process. Solid fuel samples with relatively high mercury content were examined. These included waste (refuse-derived fuel, paper, sewage sludge, and rubber), waste wood biomass (hornbeam leaves, pine and spruce bark), and six coal. The mild pyrolysis process was performed at 300 °C in an argon flow of 500 cm³/min. The residence time was 30 min. Proximate and ultimate analysis (including mercury content) was conducted for raw fuels and chars. The process allowed a significant reduction in mercury content from 36 to 97%. Mercury was most easily removed from biomass and waste with the most difficult being from coal. The effectiveness of mercury removal was determined by the type of fuel and its mercury content. The mercury content in the obtained chars was 0.05–3.4 µg Hg/MJ. The use of such chars will meet current EU emission standards and those to be introduced in the future. Full article