Contribution of prokaryotes and eukaryotes to CO2 emissions in the wastewater treatment process

Reduction of the greenhouse effect is primarily associated with the reduction of greenhouse gas (GHG) emissions. Carbon dioxide (CO₂) is one of the gases that increases the greenhouse effect - it is responsible for about half of the greenhouse effect. Significant sources of CO₂ are wastewater treatment plants (WWTPs) and waste management, with about 3% contribution to global emissions. CO₂ is produced mainly in the aerobic stage of wastewater purification and is a consequence of activated sludge activity. Although the roles of activated sludge components in the purification process have been studied quite well, their quantitative contribution to CO₂ emissions is still unknown. The emission of CO₂ caused by prokaryotes and eukaryotes over the course of a year (taking into account subsequent seasons) in model sequencing batch reactors (SBR) is presented in this study. In this work, for the first time, we aimed to quantify this contribution of eukaryotic organisms to total CO₂ emissions during the WWTP process. It is of the order of several or more ppm. The contribution of CO₂ produced by different components of activated sludge in WWTPs can improve estimation of the emissions of GHGs in this area of human activity.

Emission Characteristics of Air Pollutants and CO2 from 11 Cities with Different Economic Development around the Bohai Sea in China from 2008-2017

Cities around the Bohai Sea are one of the main population cluster areas in China, which are characterized by high levels of sustainability performance and human capital, as well as resource-intensive industries. In this study, levels of economic development metrics and emissions of air pollutants (BC, CO, NH₃, NO_x, OC, PM_2.5, PM₁₀, and SO₂) and CO₂ across eleven cities around the Bohai Sea from 2008 to 2017 were compared to illustrate the potential relationships between air pollutants/carbon emissions and socioeconomic developments. Meanwhile, the associations between the levels of economic development metrics (GDP per capita), emissions, and energy use per GDP have also been examined. Large differences across these 11 cities presenting different economic development levels and energy consumption characteristics have been observed. Cities with development dependable on the consumption of fossil fuels and the development of resource-intensive industries have emitted large amounts of air pollutants and CO₂. Furthermore, the emissions and energy use per GDP for all the cities follow environmental Kuznets curves. The comparison results suggested that the developing cities dependable on resource-intensive industries around the Bohai Sea would obtain greater socioeconomic benefits owing to the interregional cooperation policies under top-down socioeconomic development plans and bottom-up technology development, accompanied by reduced emissions of air pollutants and CO₂.

The impact of economic and environmental factors and tourism policies on the sustainability of tourism growth in China: evidence using novel NARDL model

Recently, sustainability of tourism growth has become an international issue due to environmental and economic uncertainty that needs recent researchers' focus and also requires the policymakers' attention. Therefore, the present research has examined the role of economic and environmental factors and tourism policy related to tourist arrival on the sustainability of tourism growth in China. The economic factor includes the gross domestic product (GDP), national income, and foreign direct investment (FDI), while environmental factors include carbon dioxide (CO₂) emission, greenhouse gas (GHG) emission, and nitrous oxide emission. The study has extracted the data from World Development Indicators (WDI) from 1990 to 2020. The present research has employed nonlinear autoregressive distributed lagged (NARDL) to check the linkage among variables. The current study also examines the unit root using Augmented Dickey-Fuller (ADF) and Phillips-Perron (PP) tests. The results revealed that GDP, national income, tourism policy related to tourist arrival, and FDI have a positive linkage with the sustainability of tourism growth. The results also exposed that environmental factors such as CO₂ emission, GHG emission, and nitrous oxide emission have a negative linkage with the sustainability of tourism growth. This study provides the guidelines to the relevant authorities and regulators in developing and implementing the regulators regarding the sustainability of tourism growth by promoting economic and environmental conditions and effective tourism policies in the country.

Emergy-based environmental accounting of one mining system

Metal production from mineral resources is crucial for economic development. However, most mining activities usually target short-term financial benefits, rather than long-term consideration on ecological sustainability. To better understand the impact of metal production, systematic evaluation methods should be applied to complement current economic accounting tools. Under such a circumstance, this study proposes an emergy-based metal production evaluation framework, taking a life cycle perspective from the formation of mineral deposit to the final production of metal. Ecosystem service loss, CO₂ emissions, and emissions' impact are quantified, evaluating the comprehensive performance of a lead and zinc production system in Yunnan Province of China. The results show that minerals contribute significantly to the formation of lead and zinc production; however, emergy received in terms of money substantially undervalues environmental work associated with production. Such a metal production system relies heavily on nonrenewable resources and put enormous pressures on local ecosystems. The beneficiation subsystem generates the highest negative impact per emergy output, followed by the smelting and refining subsystem and the underground mining subsystem. From climate change point of view, producing 1 ton of lead bullion leads to 1.79E+03 kg CO₂eq. Electricity use contributes a dominated share to the total CO₂ emission of all subsystems. In addition, lead recycling can greatly reduce the overall CO₂ emission, indicating that it is necessary to build up a regional lead collection and recycling system. Finally, several policy suggestions are raised by considering the local realities, aiming to promote sustainable development of this industry.

Volume and rate of volcanic CO2 emissions governed the severity of past environmental crises

The emplacement of large igneous provinces (LIPs) has been linked to catastrophic mass extinctions in Earth's history, but some LIPs are only associated with less severe oceanic anoxic events, and others have negligible environmental effects. Although it is widely accepted that massive magma outpouring can affect the environment through volatile degassing, it remains debated what controls the severity of environmental crises. Here, we demonstrate that the second-most-voluminous Phanerozoic LIP, the Kerguelen LIP, may have contributed to the early Aptian oceanic anoxic event 1a, a global event previously believed to have been caused by the Ontong Java LIP. Geochronological data show that the earliest eruptions of the Kerguelen LIP preceded the onset of oceanic anoxic event 1a by at least ∼5 million years. Analyses of CO₂ abundances in melt inclusions combined with Monte Carlo simulations reveal that the volume and degassing rate of CO₂ emissions from the Kerguelen LIP are an order of magnitude lower compared to LIPs that caused severe mass extinctions. We propose that the severity of volcanism-related environmental and biotic perturbations is positively correlated with the volume and rate of CO₂ emissions. Our results highlight the significant importance of reducing and slowing down CO₂ emission in preventing future disastrous environmental consequences.

Interrelationship among environmental policy stringency, financial globalization in OECD countries, and CO2 emission with the role of technological innovation and financial development

The study examines the nexus between financial globalization (FG), environmental policy stringency (EPS), financial development (FD), and technological innovation (INV) on CO2 emission with moderating effect of technological innovation on financial development and environmental degradation in 36 OECD countries with an updated dataset from the period of 1990 to 2020 using PMG (Pooled mean group) panel ARDL method. The results of stationarity tests; (Levin, Lin, and Chu test; ADF Fisher test) demonstrate that selected variables are stationary at level I(0) and first difference I(I); this confirms that PMG estimator can be employed. Cointegration tests indicate that cointegration exist among the variables. The empirical findings of the PMG estimator indicate that financial globalization and CO2 are negatively associated with each other. While financial development, environmental policy stringency, and technological innovation have positive impact on environmental degradation in OECD countries. Furthermore, technological innovation strengthens the association between financial development (FD) and environmental degradation (CO2 emission). In order to accelerate economic growth, the study recommends that policymakers should implement environmental policies to achieve low-carbon mechanisms, such as green infrastructure and renewable energy systems, which reduce energy consumption and greenhouse gas emissions. Therefore, it is crucial that the selected OECD countries should develop programs that increase awareness of the risks of carbon emissions.

Decomposition of Cameroon's CO2 emissions from 2007 to 2014: an extended Kaya identity

To effectively combat global warming, an enormous reduction in CO₂ emissions is required. Cameroon, which is currently the largest emitter of CO₂ in the CEMAC subregion, has committed to reducing its greenhouse gas emissions by 32% by 2035. However, previous studies in Cameroon have only addressed the relationship between economic growth, energy consumption, and CO₂ emissions without estimating all causal relationships at the same time. Moreover, no study has yet decomposed this country's CO₂ emissions to date. To fill these research gaps and further assess the determinants of these CO₂ emissions, an extended Kaya identity and the Logarithm Mean Divisia Index (LMDI I) have been applied in this paper to identify, quantify, and explain the main drivers of Cameroon's CO₂ emissions from 2007 to 2014. Seven effects were measured and the main findings show that carbon intensity and the emission factor increased by 0.57% and 107.50% respectively. Regarding contributions to the increase of CO₂ emissions, the population effect was the most positive followed by the activity effect, whereas the energy intensity, the substitution of fossil fuels and the penetration of renewable energies have contributed to reduce the CO₂ emission. To enable Cameroon to not only achieve the goals of its vision but also develop a low-carbon economy, this paper provides some proposed avenues that should be considered by policymakers.

Renewable energy, industrial upgradation, and import-export quality: green finance and CO2 emission reduction nexus

There has been a steady decline in carbon dioxide emissions in the world's 19 most industrialized nations even as GDP has increased. These nations' efforts to reduce emissions of carbon dioxide, therefore, to reduction of CO₂ and development of renewable energy are the objective of this research. With the years 1995-2019 as a point of reference, we have selected gross domestic product, GDP, RE, industrial upgrading, and import and export as our independent variables. A panel nonlinear autoregressive distributed lag (NARDL) method is utilized to investigate the links between carbon dioxide emission and these independent variables. For the purpose of determining the direction of causation, the panel heterogeneous causality test is used. RE and standards of export and import were shown to be contributing variables in the decrease of carbon dioxide emissions. The environmental Kuznets curve hypothesis was validated by the estimated findings. Increased carbon dioxide emissions are countered by the positive impulses of technological progress, such as R&D development spending and standards of import and export index. Industrial upgrading and emissions of carbon dioxide, gross domestic product and RE, and industrial upgrading and emissions of carbon dioxide, all have a bidirectional causal link. In particular, a one-way causality between gross domestic product and emissions of carbon dioxide, standards of imports and exports, and industrial upgrading, and industrial upgrading and standards of imports and exports is demonstrated. Following the results, policy suggestions are put out.

Carbon Emission and Biodiversity of Arctic Soil Microbial Communities of the Novaya Zemlya and Franz Josef Land Archipelagos

Cryogenic soils are the most important terrestrial carbon reservoir on the planet. However, the relationship between soil microbial diversity and CO₂ emission by cryogenic soils is poorly studied. This is especially important in the context of rising temperatures in the high Arctic which can lead to the activation of microbial processes in soils and an increase in carbon input from cryogenic soils into the atmosphere. Here, using high-throughput sequencing of 16S rRNA gene amplicons, we analyzed microbial community composition and diversity metrics in relation to soil carbon dioxide emission, water-extractable organic carbon and microbial biomass carbon in the soils of the Barents Sea archipelagos, Novaya Zemlya and Franz Josef Land. It was found that the highest diversity and CO₂ emission were observed on the Hooker and Heiss Islands of the Franz Josef Land archipelago, while the diversity and CO₂ emission levels were lower on Novaya Zemlya. Soil moisture and temperature were the main parameters influencing the composition of soil microbial communities on both archipelagos. The data obtained show that CO₂ emission levels and community diversity on the studied islands are influenced mostly by a number of local factors, such as soil moisture, microclimatic conditions, different patterns of vegetation and fecal input from animals such as reindeer.

Modeling Impacts of Highway Circular Curve Elements on Heavy-Duty Diesel Trucks' CO2 Emissions

Heavy-duty trucks contribute a significant component of all transportation in cargo terminals, such as Shaanxi Province, China. The emissions from these vehicles are the primary source of carbon emissions during highway operations. While several studies have attempted to address emission issues by improving traffic operations, a few focused on the relationship between emissions and highway geometric design, especially for heavy-duty trucks. The primary goal of this research was to understand the impact of circular curve on carbon dioxide (CO₂) emissions produced by heavy-duty diesel trucks. Firstly, appropriate parameters were specified in MOVES (motor vehicle emission simulator) model according to the geometrical characteristics. Fuel consumption, speed and location data were collected by hiring five skilled drivers on the automotive proving ground located at Chang’an University, Shaanxi Province. The associated carbon emission data were derived from fuel consumption data by applying the IPCC (Intergovernmental Panel on Climate Change) method. After this, the applicability of MOVES model was verified by the field experiment. Moreover, a multiple regression model for CO₂ emissions incorporated with roadway segment radius, circular curve length, and initial vehicle speed was established with data generated by the MOVES model. The proposed CO₂ emission model was also verified by field experiment with relative error of 6.17%. It was found that CO₂ emission had monotone decreasing property with radius increasing, and the minimum radius that influenced diesel CO₂ emission was 550 m. The proposed quantitative CO₂ emission model can provide a reference for low-carbon highway design, leading to environment-friendly transportation construction.

Measuring Atmospheric CO2 Enhancements From the 2017 British Columbia Wildfires Using a Lidar

During the summer 2017 ASCENDS/ABoVE airborne science campaign, the NASA Goddard CO₂ Sounder lidar overflew smoke plumes from wildfires in the British Columbia, Canada. In the flight path over Vancouver Island on 8 August 2017, the column XCO₂ retrievals from the lidar measurements at flight altitudes around 9 km showed an average enhancement of 4 ppm from the wildfires. A comparison of these enhancements with those from the Goddard Global Chemistry Transport model suggested that the modeled CO₂ emissions from wildfires were underestimated by more than a factor of 2. A spiral-down validation performed at Moses Lake airport, Washington showed a bias of 0.1 ppm relative to in situ measurements and a standard deviation of 1 ppm in lidar XCO₂ retrievals. The results show that future airborne campaigns and spaceborne missions with this type of lidar can improve estimates of CO₂ emissions from wildfires and estimates of carbon fluxes globally.

Variation of centennial precipitation patterns in Kuwait and their relation to climate change

The impact of climate change could be inferred by observing long-term climate variables like temperature, precipitation, and evapotranspiration. A local study on the climatic factors such as temperature, precipitation, CO₂ emissions, and population was carried out. The temperature records of the study period reflected an increase of 1.3 °C, higher than the global average. The relationship between the climatic factors from statistical analysis inferred that local factors did not influence the precipitation in Kuwait but showed an interrelationship among temperature, CO₂ emissions, and, population. Therefore, Kuwait's precipitation concerning regional atmospheric processes like sea surface temperature, volcanic eruption, wind direction, and El Nino and La Nina events were studied. The pragmatic change in wind direction in Kuwait from northwest to north after 2005 has enforced to study the effect of the volcanic eruption of Mount Etna on the precipitation in Kuwait. A marked correlation between the precipitation trends and post-eruptive periods of Mount Etna was observed. Similarly, El Nino and La Nina events were correlated, especially with the monthly temperature and total rainfall. Thus, the increase in sea surface temperature and volcanic events influenced the Hadley cell circulation and the shift of the Intertropical Convergence Zone, affecting the rain events in Kuwait.

Assessment of the Emission of Pollutants from Public Transport Based on the Example of Diesel Buses and Trolleybuses in Gdynia and Sopot

The present study attempts to examine the research gap in terms of comparing the environmental impact of trolleybuses and diesel buses in the conditions of a country with an unfavourable energy mix. The analysed example concerns the trolleybus transport system in Gdynia, in northern Poland, which also partially serves the neighbouring city of Sopot. In the last few years, two bus lines have been electrified with trolleybuses in the In-Motion-Charging technology, which enables operation on sections without an overhead network. Using the actual operational data, a comparative analysis of the emissivity of diesel buses and trolleybuses used on the same lines in an identical operating regime was conducted. Moreover, an attempt was made to estimate the damage costs of the emission of air pollutants for the above-mentioned means of transport. Research has shown that trolleybuses significantly help to reduce emissions of nitrogen oxides, non-methane volatile organic compounds and particulate matter, while increasing sulphur dioxide emissions on the served lines. They also generate lower specific emissions of carbon dioxide compared to diesel buses. However, taking into account the differences in the number of seats in these vehicles, the length of routes resulting from a need to provide access to the necessary infrastructure and the total amount of kilometres covered on a given route, they may cause higher emissions per year and per the product life cycle than diesel buses. This is related to the unfavourable structure of energy production in Poland, which is dominated by coal sources. The research results clearly show that the use of trolleybuses in public transport contributes to a reduction of the damage costs of the emission of pollutants that amount to approximately EUR (€) 30,000-60,000 per year for the analysed lines.

Waste Originating from the Cleaning of Flue Gases from the Combustion of Industrial Wastes as a Lime Partial Replacement in Autoclaved Aerated Concrete

This paper aims to study the suitability of partial replacement of lime by waste originating from the cleaning of flue gases from the combustion of industrial wastes in the production of autoclaved aerated concrete (AAC). The compressive strength, bulk density, pore structure, phase composition, and microstructure of hydration products of the AAC were analyzed. According to the results, the addition of the waste can effectively enhance the mechanical properties of AAC due to the differences in morphology of hydration product—1.1 nm tobermorite and related dense microstructure. The pore size distribution was significantly influenced by waste addition, which was one of the main reasons for the increase in thermal conductivity. The XRD and SEM results showed that foreign ions introduced with the wastes affect the synthesis of 1.1 nm tobermorite. Moreover, it was shown that waste containing a high content of CaO can be used as lime replacement, which allows reducing CO₂ emissions during the AAC production process.

Using an asymmetrical technique to assess the impacts of CO2 emissions on agricultural fruits in Pakistan

Human activities such as deforestation and cultivation contribute to the accumulation of carbon dioxide in the environment. Methane is emitted by energy exploration, coal mining, natural gas spills, waste, and waste dumps. Methane generated by such greenhouse gases has significantly contributed to the climate change and global warming. However, the most significant contributor to climate change and global warming is the use of fossil fuels. These fuels contribute to ozone depletion and global warming by emitting greenhouse gases into the atmosphere. The current study key objective was to determine the CO₂ emission effect to key fruit production in Pakistan by taking time series annual data varies from 1970 to 2019. A non-linear autoregressive distributed lag model (NARDL) was employed to check the variables linkages. The consequences of short- and long-run estimates expose that the positive and adverse shocks of citrus fruit create expressively to upsurge the CO₂ emission. Similarly, the positive and negative shocks of mango fruit expose an adverse interaction to CO₂ emission. The positive shock of apple fruit has constructive but negative shock expose and adverse linkage to CO₂ emission. Further, banana fruit also exposes a negative but constructive via positive shock linkage to CO₂ emission. Moving towards the apricot fruit production that exposed a constructive linkage via positive and negative shocks to CO₂ emission. The almond fruit productivity via positive and negative shocks exposed an adverse relation to carbon dioxide emission. Grape fruit via positive shock shows a construct, but negative shock exposed an adverse association to carbon emission in Pakistan. Finally the guava fruit production exposed a construct linkage to CO₂ emission via positive and negative shocks. Since agricultural activities and CO₂ emissions are essential to resolving the pollution problem, a series of practicable steps must be taken by the Pakistani authorities to tackle this issue.

Soil Water Capacity, Pore Size Distribution, and CO2 Emission in Different Soil Tillage Systems and Straw Retention

The long-term implementation of crop rotation and tillage has an impact on the soil environment through inputs and soil disturbance, which in turn has an impact on soil quality. Tillage has a long-term impact on the agroecosystems. Since 1999, a long-term field experiment has been carried out at the Experimental Station of Vytautas Magnus University. The aim of this experiment is to investigate the effects of long-term various-intensity tillage and straw retention systems on soil physical properties. The results were obtained in 2013 and 2019 (spring rape was growing). According to the latest edition of the International Soil Classification System, the soil in the experimental field was classified as Endocalcaric Stagnosol (Aric, Drainic, Ruptic, and Amphisiltic). The treatments were arranged using a split-plot design. In a two-factor field experiment, the straw was removed from one part of the experimental field, and the entire straw yield was chopped and spread at harvest in the other part of the field (Factor A). There were three different tillage systems as a subplot (conventional deep ploughing, cover cropping with following shallow termination, and no-tillage) (Factor B). There were four replications. The long-term application of reduced tillage significantly increased soil water retention and improved the pore structure and CO₂ emissions. Irrespective of the incorporation of straw, it was found that as the amount of water available to plants increases, CO₂ emissions from the soil increase to some extent and then start to decrease. Simplified tillage and no-tillage in uncultivated soil reduce CO₂ emissions by increasing the amount of water available to plants from 0.151 to 0.233 m³·m^-3.

Nexus among biomass consumption, economic growth, and CO2 emission based on the moderating role of biotechnology: evidence from China

This study seeks to dissect the basic factors that can elucidate the efficiency and innovation in biomass utilization to control carbon dioxide (CO₂) emission and economic growth nexus particularly at the time that the worldwide CO₂ emission is at an all-time high and COVID-19 is ravaging the word. We use data principally from the World Bank Indicators covering the period 1990-2016 to study the nexus among biomass utilization, economic growth, and CO₂ emission based on the moderating role of biotechnology in China. On the basis of the results of our preliminary tests, we apply the autoregressive distributed lag (ARDL) for this analysis and employ the nonlinear autoregressive distributed lag (NARDL) as a robust check and also deploy the vector error correction model (VECM) to determine the direction of causality. We find that long-run relationship exists among the factors in this study. We additionally find that biotechnology has a critical but negative relationship with CO₂ emission in China. Through hierarchical multiple regression analysis and PROCESS macro for mediation, moderation, and conditional process, we establish that biotechnology significantly moderates the relationship between biomass utilization and CO₂ emission in China. Again, we discover that biomass utilization significantly decreases CO₂ emission in China. Through the ARDL, NARDL, and VECM, we find empirical support for the growth hypothesis in China. We conduct a series of diagnostic tests that prove the robustness of our estimates. Based on our empirical evidence, this study recommends that China seeks sustainable economic development and environmental sustainability simultaneously by prioritizing biomass utilization and biotechnological innovation in the country.

The driving factors and future changes of CO2 emission in China's nonferrous metal industry

As an energy-intensive industry in China, it is critical to promote energy conservation and carbon emission reduction in the nonferrous metal industry (NMI). This study first applies the Tapio decoupling model to explore the relationships between the industrial output and CO₂ emission in China's NMI. Then, the Generalized Divisia Index Model (GDIM) is adopted to uncover the factors driving the changes in CO₂ emission from 2000 to 2019, and based on the decomposition results, scenario analysis is used to predict potential CO₂ emission during 2021-2035. The results show that (1) the CO₂ emission in China's NMI increases by 397.93 million tons (Mt) during 2000-2019, and the decoupling state between the industrial output and CO₂ emission is characterized by the weak decoupling status; (2) overall, the output scale is the dominant factor promoting the CO₂ emissions increase, followed by the investment scale and energy consumption scale, while the carbon intensity of output and the carbon intensity of investment are the two most important abatement factors; (3) the scenario analysis indicates that the CO₂ emission from NMI will peak around 2030 under the low-carbon scenario while 2026 under the enhanced low-carbon scenario. Policy suggestions are further put forward for carbon emission reduction in China's NMI.

Analysis of the decoupling state and driving forces of China's construction industry under the carbon neutrality target

The essential to achieving the 2060 carbon neutrality target in China lies in the performance of the construction industry. Decoupling economic development from CO₂ emissions is the main strategy for reducing emissions in the construction industry. This paper is based on panel data for China and its 30 provinces during 2009-2019. A Tapio decoupling model is constructed to analyze the decoupling state of economic development and CO₂ emissions in the construction industry. The logarithmic mean Divisia index model is constructed to continue the decomposition of the drivers of the decoupling state and CO₂ emissions. The results show that (1) the economic development level of most provinces is positively correlated with their CO₂ emissions; (2) Beijing and Jiangsu reach the ideal strong decoupling state, and Heilongjiang has the worst decoupling state. The same type of decoupling state shows a certain aggregation phenomenon in space; (3) economic output plays a critical role in promoting CO₂ emissions and decoupling of the construction industry in China and the provinces. The main driver of decoupling is indirect carbon intensity; (4) energy intensity has a greater impact on CO₂ emissions reduction in regions with more developed economic levels. Understanding the drivers of the decoupling state in China's construction industry provides a valuable basis for energy efficiency and emission reduction efforts in China and other countries.

Effect of Ornamental Stone Waste Incorporation on the Rheology, Hydration, Microstructure, and CO2 Emissions of Ordinary Portland Cement

The ornamental stone industry generates large amounts of waste thus creating environmental and human health hazards. Thus, pastes with 0–30 wt.% ornamental stone waste (OSW) incorporated into ordinary Portland cement (OPC) were produced and their rheological properties, hydration kinetics, and mechanical properties were evaluated. The CO₂ equivalent emissions related to the pastes production were estimated for each composition. The results showed that the paste with 10 wt.% of OSW exhibited similar yield stress compared to the plain OPC paste, while pastes with 20 and 30 wt.% displayed reduced yield stresses up to 15%. OSW slightly enhanced the hydration kinetics compared to plain OPC, increasing the main heat flow peak and 90-h cumulative heat values. The incorporation of OSW reduced the 1-, 3-, and 28-days compressive strength of the pastes. Water absorption results agreed with the 28 days compressive strength results, indicating that OSW increased the volume of permeable voids. Finally, OSW incorporation progressively reduced the CO₂ emission per m³ of OPC paste, reaching a 31% reduction for the highest 30 wt.% OSW content. Overall, incorporating up to 10 wt.% with OSW led to pastes with comparable fresh and hardened properties as comported to plain OPC paste.

Research on the economic abatement pathway of carbon peaking in China based on marginal abatement costs and abatement tasks allocation

China needs to achieve its carbon peaking target with minimal economic costs. This paper proposes a framework for achieving the carbon peaking target that emphasizes economic effects. Based on the prediction, the parametric directional distance function (DDF) is adopted to calculate the total factor carbon emission efficiency and marginal carbon abatement cost in each region of China before 2030, and the allocation scheme of the abatement tasks necessary for carbon peaking is optimized from the perspective of least cost. The empirical results show the following: (1) The predicted rapid growth of China's economy from 2020 to 2030 will lead to a rapid increase in marginal abatement costs, with the average marginal carbon abatement cost increasing from 8,833 yuan/ton to 15,077 yuan/ton. The cost of carbon emission reduction in the future is very expensive. (2) The measured marginal abatement costs in China are positively correlated with carbon emission efficiency. In order to ensure economic development, developed regions should try to maintain the development trend, while the central and western regions take on more emission reduction tasks. (3) The emission efficiency is improved by optimizing the allocation scheme of the abatement tasks required to reach the peak, and the scientific and orderly path to reach the peak of each province and the corresponding lowest economic cost are obtained. This paper are of great theoretical and practical significance for the initial quota allocation in carbon trading market and ensuring the achievement of carbon peaking target under economic effect.

Carbon Mitigation Pathways of Urban Transportation under Cold Climatic Conditions

Climate heterogeneity has enormous impacts on CO₂ emissions of the transportation sector, especially in cold regions where the demand for in-car heating and anti-skid measures leads to high energy consumption, and the penetration rate of electric vehicles is low. It entails to propose targeted emission reduction measures in cold regions for peaking CO₂ emissions as soon as possible. This paper constructs an integrated long-range energy alternatives planning system (LEAP) model that incorporates multi-transportation modes and multi-energy types to predict the CO₂ emission trend of the urban transportation sector in a typical cold province of China. Five scenarios are set based on distinct level emission control for simulating the future trends during 2017–2050. The results indicate that the peak value is 704.7–742.1 thousand metric tons (TMT), and the peak time is 2023–2035. Energy-saving–low-carbon scenario (ELS) is the optimal scenario with the peak value of 716.6 TMT in 2028. Energy intensity plays a dominant role in increasing CO₂ emissions of the urban transportation sector. Under ELS, CO₂ emissions can be reduced by 68.66%, 6.56% and 1.38% through decreasing energy intensity, increasing the proportion of public transportation and reducing the proportion of fossil fuels, respectively. Simultaneously, this study provides practical reference for other cold regions to formulate CO₂ reduction roadmaps.

Nitrapyrin Addition Mitigated CO2 Emission from a Calcareous Soil Was Closely Associated with Its Effect on Decreasing Cellulolytic Fungal Community Diversity

Application of nitrification inhibitors (NIs) has been widely used to inhibit nitrification and reduce N₂O emissions. However, the impacts of NI addition on soil carbon transformation and carbon-degrading microbial communities have not been well explored. Here, a microcosm experiment was carried out, and four treatments were designed: (i) unfertilized control, (ii) urea alone, (iii) urea plus cattle manure, and (iv) urea plus cattle manure with nitrapyrin. The influence of nitrapyrin on soil CO₂ emissions, carbon-degrading extracellular enzyme activities, and the abundance and diversity of the cbhI community was investigated. Compared to the treatment of urea plus cattle manure, nitrapyrin significantly decreased cumulative CO₂ emissions by 51.8%. Moreover, cbhI community gene copies and their α-diversities (P < 0.05) were also significantly reduced by nitrapyrin application. A partial least squares path model showed that CO₂ emission was positively associated with cbhI community α-diversity but negatively associated with nitrapyrin addition. We conclude that the mitigation of soil CO₂ emissions by nitrapyrin can be ascribed to its effects on decreasing of cellulose-degrading gene community diversity. Our findings provide new insights into the side-effects of nitrapyrin on abating CO₂ emission.

Heavy Metal Pollution in the Ganga River Enhances Carbon Storage Relative to Flux

This study evaluated the relationships between metal pollution and carbon production at six sites along a 285 km length of the Ganga River. Metal contaminated sites did show a significant reduction in microbial biomass, substrate induced respiration, fluorescein diacetate hydrolytic assay (FDAase) and β-D-glucosidase. Concordantly, despite a high concentration of total organic carbon at these sites, CO₂ emission at the land-water interface remained low. We found a strong positive correlation between CO₂ emission and TOC (r = 0.92; p < 0.001). However, this relationship weakens when the sum of total heavy metal (∑THM) exceed 400 µg g^-1. Also, CO₂ emission did show a positive correlation (r = 0.85; p < 0.001) with FDAase. The study shows that metal accumulation in riverbed sediment could potentially lead to better carbon sequestration on account of reduced microbial/enzyme activities. This carries significance for riverine carbon budget and modeling.

Growth-corruption-health triaca and environmental degradation: empirical evidence from Indonesia, Malaysia, and Thailand

This study examines the impact of economic growth, corruption, health, and poverty on environmental degradation for three countries from ASEAN, namely Indonesia, Malaysia, and Thailand using annual data over the period of 1994-2014. The relationship between environmental degradation (pollution) by carbon dioxide (CO₂) emissions and economic growth is examined along with some other variables, namely health expenditure, poverty, agriculture value added growth, industrial value added growth, and corruption. The ordinary least squares (OLS) method is applied as an analytical technique for parameter estimation. The empirical results reveal that almost all variables are statistically significant at the 5% level of significance, whereby test rejects the null hypotheses of non-cointegration, indicating that all variables play an important role in affecting the environment across countries. Empirical results also indicate that economic growth has significant positive impact, while health expenditures show significantly negative impact on the environment. Corruption has significant positive effect on environment in the case of Malaysia; while in the case of Indonesia and Thailand, it has insignificant results. However, for the individual analysis across countries, the regression estimate suggests that economic growth has a significant positive relationship with environment for Indonesia, while it is found insignificantly negative and positive in the case of Malaysia and Thailand, respectively, during the period under the study. Empirical findings of the study suggest that policy-makers require to make technological-friendly environment sequentially to surmount unregulated pollution, steady population transfers from rural areas to urban areas are also important, and poverty alleviation and better health provision can also help to improve the environment.