Regional Greenhouse Gas Research Articles

Spatial and Temporal Variability and Driving Factors of Carbon Dioxide and Nitrous Oxide Fluxes in Alpine Wetland Ecosystems.

Plants regulate greenhouse gas (GHG) fluxes in wetland ecosystems, but the mechanisms of plant removal and plant species that contribute to GHG emissions remain unclear. In this study, the fluxes of carbon dioxide (CO2) and nitrous oxide (N2O) were measured using the static chamber method from an island forest dominated by two different species, namely Betula platyphylla (BP) and Larix gmelinii (LG), in a marsh wetland in the Great Xing'an Mountains. Four sub-plots were established in this study: (1) bare soil after removing vegetation under BP (SBP); (2) bare soil after removing vegetation under LG (SLG); (3) soil with vegetation under BP (VSBP); and (4) soil with vegetation under LG (VSLG). Additionally, the contributions of the dark respiration from plant aerial parts under BP (VBP) and LG (VLG) to GHG fluxes were calculated. We found that the substantial spatial variability of CO2 fluxes ranged from -25.32 ± 15.45 to 187.20 ± 74.76 mg m-2 h-1 during the study period. The CO2 fluxes decreased in the order of SBP > VSLG > VSBP > SLG > VLG > VBP, indicating that vegetation species had a great impact on CO2 emissions. Particularly, the absence of vegetation promoted CO2 emission in both BP and LG. Additionally, CO2 fluxes showed dramatically seasonal variations, with high CO2 fluxes in late spring (May) and summer (June, July, and August), but low fluxes in late summer (August) and early autumn (September). Soil temperatures at 0-20 cm depth were better predictors of CO2 fluxes than deeper soil temperatures. N2O fluxes were varied in different treatments with the highest N2O fluxes in SLG and the lowest N2O fluxes in VBP. Meanwhile, no significant correlation was found between N2O fluxes and air or soil temperatures. Temporally, negative N2O fluxes were observed from June to October, indicating that soil N2O fluxes were reduced and emitted as N2, which was the terminal step of the microbial denitrification process. Most of the study sites were CO2 sources during the warm season and CO2 sinks in the cold season. Thus, soil temperature plays an important role in CO2 fluxes. We also found that the CO2 flux was positively related to pH in a 10 cm soil layer and positively related to moisture content (MC) in a 50 cm soil layer in VSBP and VSLG. However, the CO2 flux was negatively related to pH in a 30 cm soil layer in SBP and SLG. Our findings highlight the effects of vegetation removal on GHG fluxes, and aid in the scientific management of wetland plants.

Development and feasibility assessment of on-board catalytic reforming system for LPG engine to produce hydrogen in the transient state

Despite tightening greenhouse gas regulations and the trend of electrification of power train, if hybrid systems are considered, internal combustion engines are expected to be used consistently. Therefore, research on low-emission engines that can be instantly applied should be continued. Liquefied petroleum gas is a low pollutant fuel applicable to spark ignition engines as an alternative fuel. In this study, to maximize the advantages of liquefied petroleum gas, a catalytic reforming system was applied to an internal combustion engine and tested under actual operating conditions. A catalytic reforming system is a technology that reforms a part of the fuel supplied to the engine through a reforming catalyst and supplies it to the intake manifold. When properly controlled, fuel efficiency and pollutant emissions can be improved. To effectively operate the system, the engine was controlled by dividing operating conditions into a general driving zone, a lean burn zone, and a catalytic reforming zone. finally, the fuel efficiency and NOx emissions were evaluated. As a result of the evaluation under the modified FTP-72 condition, NOx emission was reduced by 22.83%, and fuel efficiency was improved by 3.01%.

Mahuika‐Auckland: A spatially and temporally resolved fossil fuel CO2 emissions data product for Auckland, New Zealand

AbstractAccurate, high‐resolution and sector‐specific greenhouse gas emissions information is increasingly needed for the development of local, targeted mitigation policies. We describe a detailed, spatially and temporally resolved CO2 emissions data product, Mahuika‐Auckland, for Auckland, New Zealand, based on Auckland's regional greenhouse gas and air emissions inventories. Emissions are provided at 500 m spatial resolution and at a 1‐hr time step, a level of detail not previously available for any New Zealand city. We divide fossil fuel emissions into six sectors that comprise the majority of Auckland Region's CO2 emissions profile: on‐road transport, industrial non‐point buildings and point sources, commercial non‐point buildings, residential non‐point buildings, air transport and sea transport. We also include separate layers representing biogenic CO2 emissions (primarily waste and wood burning), as these are significant sources in Auckland. We distribute emissions spatially and temporally based on activity data, energy and fuel consumption patterns, and population statistics. The code to generate Mahuika‐Auckland has been designed to be flexible so that updated information and/or data from more recent years can easily be incorporated. This data product improves upon New Zealand's current inventories that are only resolved at the regional and annual scale, providing a new level of detail that can be used as a prior estimate for atmospheric inversions, to inform emissions reduction policies and to guide the development of zero carbon pathways.

Response of Soil Respiration Rates to Soil Temperature and Moisture at Different Soil Depths of Caragana korshinskii Plantation in the Loess-Hilly Region

It is of great significance to clarify the influence of soil temperature and moisture on soil respiration rate and its characteristics in ecologically fragile regions under the background of climate change for the accurate assessment and prediction of carbon budgets in this region. The average CO2 concentration and soil temperature and moisture at different soil depths (10, 50, and 100 cm) were measured using a CO2 analyzer and temperature and moisture sensors. The soil respiration rate was calculated using Fick's first diffusion coefficient method. The dynamic characteristics of soil temperature, soil moisture, and soil respiration rate in different soil depths were explored, and the response of soil respiration rate to soil temperature and moisture were further analyzed. The results showed that the diurnal variation in soil respiration rate decreased significantly with the increase in soil depth (P<0.05), and the peak time lagged behind. Soil respiration rate in adjacent soil depths (10, 50, and 100 cm) lagged 1 h from top to bottom. The monthly variation in soil respiration rate was a multi-peak curve, in which the maximum soil respiration rates of 10, 50, and 100 cm soil depths were on July 25th, August 6th, and August 10th, reaching 13.96, 2.96, and 1.47 μmol·(m2·s)-1, respectively. The effect of soil temperature on soil respiration rate decreased with the increase in soil depth. Soil temperature at 50 cm and below had no significant effect on soil respiration rate (P>0.05). The fitting index of 10 cm soil depth was the best (R2=0.96), but the fitting indexes of 50 cm and 100 cm soil depths were poor (R2=0.00 and R2=0.01, respectively). The temperature sensitivity coefficient Q10 decreased with the increase in soil depth. Soil moisture in different soil depths had significant effects on soil respiration rate (P<0.05), and the quadratic fitting indicated that 50 cm (R2=0.35)>10 cm (R2=0.22)>100 cm (R2=0.31). The combined effects of soil temperature and moisture in different soil depths could explain 96%, 6%-50%, and 22%-24% of soil respiration rate, respectively. In summary, the effects of soil temperature and moisture at different soil depths of the Caragana korshinskii plantation in the loess-hilly region on soil respiration rate differed. The soil respiration rate of the 10 cm soil depth was affected by the comprehensive effect of soil temperature and moisture; however, the relative contribution of soil temperature was higher, and soil moisture at and below a soil depth of 50 cm was the key factor. These results could help improve predictions on the impact of future climate change on the carbon cycle of terrestrial ecosystems in the region and provide a theoretical basis for greenhouse gas regulation in the future.

Does the US regional greenhouse gas initiative affect green innovation?

This study measures the impact of the implementation of the Regional Greenhouse Gas Initiative (RGGI) on firms’ green innovation initiatives. We used 20 years of panel data from the Fortune 500 list of the US largest companies. Based on DID, a benchmark regression, the RGGI has a significant adverse effect on the green innovation of Fortune 500 companies, and we verified these findings with multiple robustness tests. As we investigate how energy-intensive industries were affected by RGGI, we found that it slowed down green innovation, but it was not statistically significant. This study provides a novel perspective on how the RGGI influences green innovation in firms and how different types of sectors respond to the policy. The findings indicate that the “weak” Porter Hypothesis has not been confirmed in the present carbon trading market (particularly the RGGI) for Fortune 500 firms in the USA. In terms of policy, we believe that a well-covered and differentiated legislation that fosters green innovation while being realistic about the policy’s goal and the firm’s environmental attitude, like emissions reduction through green innovation, is essential.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-022-23189-0.

Estimating Regional Methane Emission Factors from Energy and Agricultural Sector Sources Using a Portable Measurement System: Case Study of the Denver-Julesburg Basin.

Methane (CH4), a powerful greenhouse gas (GHG), has been identified as a key target for emission reduction in the Paris agreement, but it is not currently clear where efforts should be focused to make the greatest impact. Currently, activity data and standard emission factors (EF) are used to generate GHG emission inventories. Many of the EFs are globally uniform and do not account for regional variability in industrial or agricultural practices and/or regulation. Regional EFs can be derived from top–down emissions measurements and used to make bespoke regional GHG emission inventories that account for geopolitical and social variability. However, most large-scale top–down approaches campaigns require significant investment. To address this, lower-cost driving surveys (DS) have been identified as a viable alternative to more established methods. DSs can take top–down measurements of many emission sources in a relatively short period of time, albeit with a higher uncertainty. To investigate the use of a portable measurement system, a 2260 km DS was conducted throughout the Denver–Julesburg Basin (DJB). The DJB covers an area of 8000 km2 north of Denver, CO and is densely populated with CH4 emission sources, including oil and gas (O and G) operations, agricultural operations (AGOs), lakes and reservoirs. During the DS, 157 individual CH4 emission sources were detected; 51%, 43% and 4% of sources were AGOs, O and G operations, and natural sources, respectively. Methane emissions from each source were quantified using downwind concentration and meteorological data and AGOs and O and G operations represented nearly all the CH4 emissions in the DJB, accounting for 54% and 37% of the total emission, respectively. Operations with similar emission sources were grouped together and average facility emission estimates were generated. For agricultural sources, emissions from feedlot cattle, dairy cows and sheep were estimated at 5, 31 and 1 g CH4 head−1 h−1, all of which agreed with published values taken from focused measurement campaigns. Similarly, for O and G average emissions for well pads, compressor stations and gas processing plants (0.5, 14 and 110 kg CH4 facility−1 h−1) were in reasonable agreement with emission estimates from intensive measurement campaigns. A comparison of our basin wide O and G emissions to measurements taken a decade ago show a decrease of a factor of three, which can feasibly be explained by changes to O and G regulation over the past 10 years, while emissions from AGOs have remained constant over the same time period. Our data suggest that DSs could be a low-cost alternative to traditional measurement campaigns and used to screen many emission sources within a region to derive representative regionally specific and time-sensitive EFs. The key benefit of the DS is that many regions can be screened and emission reduction targets identified where regional EFs are noticeably larger than the regional, national or global averages.

Carbon management strategy effects on the disclosure and efficiency of carbon emissions: A study of Colombian companies’ context and inherent characteristics

The purpose of this study is to identify the contextual characteristics and the company-inherent characteristics to analyze the disclosure of carbon emissions and the efficiency of emissions from the incorporation of a Carbon Management Strategy. This study is based on two models: i) Carbon emissions disclosure and ii) Efficiency of carbon emissions. We develop the models using the relationship between A) the adoption of a Carbon Management Strategy and the disclosure of carbon emissions and B) the impact of having a Carbon Management Strategy and the efficiency of direct and indirect emissions by Colombian companies. We use an Ordinary Least Square regression model for the carbon emissions disclosure model and a robust Ordinary Least Square model on the efficiency model of carbon emissions based on a balanced panel data of Colombian listed companies for the period 2016–2019 and we take sub-samples to analyze scope 1, scope 2 and scope 3. The study includes variables in relation to the companies’ context (fiscal strategy through carbon taxation and geographical location) and company-inherent characteristics (size and sensitive industry sector). The results of the carbon emissions disclosure model suggest that, in large companies, there is a positive relationship between the adoption of a Carbon Management Strategy and the disclosure of emissions for scopes 1 and 2. Sensitive industries disclose the three scope levels. In the regional analysis, the quantitative information on the scope is scarce and suggests that companies are not willing to disclose information that sends a negative signal of their environmental actions to the stakeholders. The results of the carbon emissions efficiency model show an important connection with the indebtedness of companies as a leverage mechanism to acquire technology or manage innovation projects for a more efficient management of Greenhouse Gas emissions. Shareholders also have an impact on efficiency. This is associated with a growing interest in incorporating environmental criteria into their investment decisions and the effect of obtaining information on emissions through voluntary reports. The Carbon Management Strategy index is positive for the efficiency of controlled indirect emissions (scope 2). This finding suggests that emission reduction strategies focus on the management of electricity consumption or the use of renewable sources to improve financial costs and emission indicators. This study is innovative because it is focused on a country without established Greenhouse Gas regulations and it is in a complex scenario where political stability and the rule of law are affected. This study raises a potential topic to explore further because the topic is in a germinal stage in the academic and business field.

How Does State-Level Carbon Pricing in the United States Affect Industrial Competitiveness?

Pricing carbon emissions from an individual jurisdiction may harm the competitiveness of local firms, causing the leakage of emissions and economic activity to other regions. Past research concentrates on national carbon prices, but the impacts of subnational carbon prices could be more severe due to the openness of regional economies. We specify a flexible model to capture competition between a plant in a state with electric sector carbon pricing and plants in other states or countries without such pricing. Treating energy prices as a proxy for carbon prices, we estimate model parameters using confidential plant-level Census data, 1982–2011. We simulate the effects on manufacturing output and employment of carbon prices covering the Regional Greenhouse Gas Initiative (RGGI) in the Northeast and Mid-Atlantic regions. A carbon price of $10 per metric ton on electricity output reduces employment in the regulated region by 2.1 percent, and raises employment in nearby states by 0.8 percent, although these estimates do not account for revenue recycling in the RGGI region that could mitigate these employment changes. The effects on output are broadly similar. National employment falls just 0.1 percent, suggesting that domestic plants in other states as opposed to foreign facilities gain the most jobs from state or regional carbon pricing.

Carbon and nutrients regulate greenhouse gas fluxes from oxic stream sediments

Carbon and nutrients regulate greenhouse gas fluxes from oxic stream sediments

A new index on agricultural land greenhouse gas emissions in Africa.

Africa emits the lowest amounts of greenhouse gases (GHGs) into the global GHG budget. However, the continent remains the most vulnerable continent to the effects of climate change. The agricultural sector in Africa is among the most vulnerable sectors to climate change. Also, as a dominant agricultural sector, African agriculture is increasingly contributing to climate change through GHG emissions. Research has so far focused on the effects of GHG emissions on the agricultural and other sectors with very little emphasis on monitoring and quantifying the spatial distribution of GHG emissions from agricultural land in Africa. This study develops a new index: African Agricultural Land Greenhouse Gas Index (AALGGI) that uses scores and specific scale ranges for carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) to map the spatial variations in regional GHG emissions across Africa. The data for the three main GHGs (CO2, CH4, and N20) were downloaded from FAOSTAT. The data were analyzed through the newly developed African Agricultural Land Greenhouse Gas Index (AALGGI). This is an empirical index with scores ranging from 0 to 10, with higher scores indicating higher levels of emissions. The results show that Southern and North African regions have the lowest amounts of agricultural land GHG emissions, with AALGGIs of 3.5 and 4.5, respectively. East Africa records the highest levels of GHG emissions, with an AALGGI of 8 followed by West Africa with an AALGGI of 7.5. With the continental mean or baseline AALGGI being 5.8, East and Middle Africa are above the mean AALGGI. These results underscore the fact that though Africa, in general, is not a heavy emitter of GHGs, African agricultural lands are increasingly emitting more GHGs into the global GHG budget. The low AALGGIs in the more developed parts of Africa such as Southern and North Africa are explained by their domination in other GHG emitting sectors such as industrialization and energy. The high rates of emissions in East Africa and Middle Africa are mainly linked to intensive traditional farming practices/processes and deforestation. These findings underscore the need to further leverage climate change mitigation actions and policy in Africa and most importantly the co-benefits of mitigation and adaptations in the most vulnerable regions.

Environmental justice and power plant emissions in the Regional Greenhouse Gas Initiative states.

Policies to reduce greenhouse gases associated with electricity generation have been a major focus of public policy in the United States, but their implications for achieving environmental justice among historically overburdened communities inappropriately remains a marginal issue. In this study we address research gaps in historical and current ambient air emissions burdens in environmental justice communities from power plants participating in the Regional Greenhouse Gases Initiative (RGGI), the country's first market-based power sector emissions reduction program. We find that in RGGI states the percentage of people of color that live within 0-6.2 miles from power plants is up to 23.5 percent higher than the percent of the white population that lives within those same distance bands, and the percentage of people living in poverty that live within 0-5 miles from power plants is up to 15.3 percent higher than the percent of the population not living in poverty within those same distance bands. More importantly, the transition from coal to natural gas underway before RGGI formally started resulted in large increases in both the number of electric-generating units burning natural gas and total net generation from natural gas in environmental justice communities hosting electric-generating units, compared to other communities. Our findings indicate that power sector carbon mitigation policies' focusing on aggregate emissions reductions have largely benefitted non-environmental justice communities and have not redressed the fundamental problem of disparities in pollutant burdens between EJ and non-EJ communities. These must be directly addressed in climate change and carbon emissions mitigation policy.

The BosWash Infrastructure Biome and Energy System Succession

The BosWash corridor is a megalopolis, or large urbanized region composed of interconnected transportation, infrastructure, physiography, and sociopolitical systems. Previous work has not considered the BosWash corridor as an integrated, holistic ecosystem. Building on the emerging field of infrastructure ecology, the region is conceptualized here as an infrastructure biome, and this concept is applied to the region’s energy transition to a post-fossil fueled heating sector, in analogy to ecosystem succession. In this conception, infrastructure systems are analogous to focal species. A case study for an energy succession from an aging natural gas infrastructure to a carbon-free heating sector is presented, in order to demonstrate the utility of the infrastructure biome framework to address climate and energy challenges facing BosWash communities. Natural gas is a dominant energy source that emits carbon dioxide when burned and methane when leaked along the process chain; therefore, a transition to electricity is widely seen as necessary toward reducing greenhouse gas emissions. Utilizing an infrastructure biome framework for energy policy, a regional gas transition plan akin to the Regional Greenhouse Gas Initiative is generated to harmonize natural gas transition within the BosWash infrastructure biome and resolve conflict arising from a siloed approach to infrastructure management at individual city and state levels. This work generates and utilizes the novel infrastructure biome concept to prescribe a regional energy policy for an element of infrastructure that has not previously been explored at the regional scale—natural gas.

Characterization and mitigation option of greenhouse gas emissions from lactating Holstein dairy cows in East China

BackgroundThis study investigated greenhouse gas (GHG) emission characteristics of lactating Holstein dairy cows in East China and provided a basis for formulating GHG emission reduction measures. GreenFeed system was used to measure the amount of methane (CH4) and carbon dioxide (CO2) emitted by the cows through respiration. Data from a commercial cow farm were used to observe the effects of parity, body weight, milk yield, and milk component yield on CH4 and CO2 emissions.ResultsMean herd responses throughout the study were as follows: 111 cows completed all experimental processes, while 42 cows were rejected because they were sick or had not visited the GreenFeed system 20 times. On average, lactating days of cows was 138 ± 19.04 d, metabolic weight was 136.5 ± 9.5 kg, parity was 2.8 ± 1.0, dry matter intake (DMI) was 23.1 ± 2.6 kg/d, and milk yield was 38.1 ± 6.9 kg/d. The GreenFeed system revealed that CH4 production (expressed in CO2 equivalent, CO2-eq) was found to be 8304 g/d, {mathrm{CH}}_{4left({mathrm{CO}}_2-mathrm{eq}right)} /DMI was 359 g/kg, {mathrm{CH}}_{4left({mathrm{CO}}_2-mathrm{eq}right)} /energy-corrected milk (ECM) was 229.5 g/kg, total CO2 production (CH4 production plus CO2 production) was 19,201 g/d, total CO2/DMI was 831 g/kg, and total CO2/ECM was 531 g/kg. The parity and metabolic weight of cows had no significant effect on total CO2 emissions (P > 0.05). Cows with high milk yield, milk fat yield, milk protein yield, and total milk solids yield produced more total CO2 (P < 0.05), but their total CO2 production per kg of ECM was low (P < 0.05). The total CO2/ECM of the medium and high milk yield groups was 17% and 27% lower than that of the low milk yield group, respectively.ConclusionsThe parity and body condition had no effect on total CO2 emissions, while the total CO2/ECM was negatively correlated with milk yield, milk fat yield, milk protein yield, and total milk solids yield in lactating Holstein dairy cows. Measurement of total CO2 emissions of dairy cows in the Chinese production system will help establish regional or national GHG inventories and develop mitigation approaches to dairy production regimes.

Soil Cycles of Elements simulator for Predicting TERrestrial regulation of greenhouse gases: SCEPTER v0.9

Abstract. The regulation of anthropogenic carbon dioxide (CO2) is an urgent issue – continuously increasing atmospheric CO2 from burning fossil fuels is leading to significant warming and acidification of the surface ocean. Timely and effective measures to curb CO2 increases are thus needed in order to mitigate the potential degradation of natural ecosystems, food security, and livelihood caused by anthropogenic release of CO2. Enhanced rock weathering (ERW) on croplands and hinterlands may be one of the most economically and ecologically effective ways to sequester CO2 from the atmosphere, given that these soil environments generally favor mineral dissolution and because amending soils with crushed rock can result in a number of co-benefits to plant growth and crop yield. However, robust quantitative evaluation of CO2 capture by ERW in terrestrial soil systems that can lead to coherent policy implementation will require an ensemble of traceable mechanistic models that are optimized for simulating ERW in managed systems. Here, we present a new 1D reactive transport model – SCEPTER. The model is designed to (1) mechanistically simulate natural weathering, including dissolution/precipitation of minerals along with uplift/erosion of solid phases, advection plus diffusion of aqueous phases and diffusion of gas phases, (2) allow targeted addition of solid phases at the soil–atmosphere interface, including multiple forms of organic matter (OM) and crushed mineral/rock feedstocks, (3) implement a range of soil mixing regimes as catalyzed by soil surface fauna (e.g., bioturbation) or humans (e.g., various forms of tilling), and (4) enable calculation of solid mineral surface area based on controlled initial particle size distributions coupled to a shrinking core framework. Here we describe the model structure and intrinsic thermodynamic/kinetic data, provide a series of idealized simulations to demonstrate the basic behavior of the code, and evaluate the computational and mechanistic performance of the model against observational data. We also provide selected example applications to highlight model features particularly useful for future prediction of CO2 sequestration by ERW in soil systems.

Greenhouse gas emissions and poverty alleviation nexus in the Economic Commission of West African States

AbstractThis paper investigates the nexus between greenhouse gas emissions and poverty alleviation in the Economic Commission of West African States between 1985 and 2020 applying autoregressive distributed lag and Granger causality techniques. The results reveal that carbon dioxide non‐significantly relates to gross domestic product per capita positively while nitrous oxide and foreign direct investment impacts gross domestic product per capita positively. Methane negatively impacts gross domestic product per capita. The governments should use conventions to regulate greenhouse gas emissions’ effects on environmental degradation regionally and globally. The study underscores that countries should diversify to cleaner energy sources. This would reduce greenhouse gas emissions in the atmosphere. Massive technological investment is required to mitigate the greenhouse gas emissions’ negative impacts on the environment which create poverty. This policy implication ensures environmental sustainability and reverses the ugly trend of greenhouse gas emissions on poverty.

Environmental life cycle evaluation of prefabricated residential construction in China

Due to rapid urbanization, the construction industry in China consumes a significant quantity of material and is responsible for considerable greenhouse gas emissions. Prefabricated construction methods are promoted by the Chinese government because of their potential environmental and economic benefits towards enhancing the productivity and quality of built structures and on-site construction-related pollution. This research investigates the environmental tradeoffs offered by prefabrication methods compared to traditional cast in-situ methods using life cycle assessment (LCA), focusing on primary non-renewable energy, global warming, terrestrial acidification, human carcinogenic toxicity, fine particulate matter formation and eutrophication using a cradle-to-final construction system boundary. Primary data collected from two residential projects under construction in 2019–2020 and built by prefabrication and traditional construction methods in China were compared. This study investigates parameter uncertainty on regional greenhouse gas (GHG) emissions related to electricity production. The results reveal that except for marine eutrophication, prefabrication methods offer more environmental advantages compared to traditional methods for all impact categories. The uncertainty analysis showed that the GHG emission factor for electricity production is not significant within the system boundary. Future research should investigate uncertainty among other parameters related to the building materials in the context of Chinese production. The findings of the study can provide a basis for policy makers in promoting sustainable construction in the context of China.

Photodegradation of pyrogenic dissolved organic matter increases bioavailability: Novel insight into bioalteration, microbial community succession, and C and N dynamics

Photodegradation and biodegradation of pyrogenic dissolved organic matter (pyDOM) play crucial roles in regulating greenhouse gas emissions and stabilizing organic matter. In this study, we conducted a 56-day microbial laboratory incubation to investigate the biodegradation patterns of pristine and photobleached pyDOM leached from a thermal series of chars (300, 450, and 600 °C) based on FT-ICR-MS, gas analysis, N speciation, and 16S rDNA sequencing. As the pyrolysis temperature increased, the among of biomineralized carbon of pyDOM decreased, while the molecular diversity and aromaticity increased. Photobleaching increased the among of biomineralized carbon of pyDOM from 40%–70% to 60%–80%, but decreased the molecular diversity, molecular weight, and aromaticity, with a major removal of lignin-like compounds. Microbial incubation lowered the molecular diversity but increased the molecular weight and aromaticity of both pristine and photobleached samples. Tannin-like structures, carbohydrates, and aliphatic/protein were preferentially biodegraded, while lipid, lignin-like structures, unsaturated hydrocarbons, and condensed aromatics were more likely to be preserved or newly produced. The photobio-resistant components were mainly comprised of lignin-like and tannin-like structures. Photobleached pyDOM samples released more CO2 but less N2O, as they may possess high denitrification rate due to their high carbon reactivity. The bacterial richness and diversity in pyDOM were lower than the original inoculum. In addition, distinct differences were noted between the bacterial community structure of the original inoculum and that of pristine and photobleached pyDOM samples following various incubation times. Specifically, proteobacteria was increased and remained the predominant phylum in all pyDOM solutions compared to the original inoculum, while Actinobacteriota, Bdellovibrionota, Firmicutes, or Nitrospirota phyla were increased in several samples either after 7 or 56 days of incubation. In particular, photobleached pyDOM pyrolyzed at 600 °C exhibited the strongest filtration effects on the bacterial microflora. These results help to elucidate the biogeochemical cycling and turnover of pyDOM in sunlit and dark aquatic environments such as fluvial and groundwater networks, lakes, and the ocean.

Climate variability and change in Tibetan Plateau within a warming climate

Global warming has become a subject of concern with an increasing number of natural disasters under the excessive emission of greenhouse gasses, influencing many sectors of environment, society, and economy. Likewise, the climate of the Tibetan Plateau region (known as “the roof of the world”) is closely related to global warming. Yet, the variation and prediction of climate in Tibetan Plateau remain unresolved. The purpose of this research is to diagnose and forecast the climate change in Tibetan Plateau in China within the context of global warming based on surface temperature and precipitation data. Specifically, the results suggest that global warming closely affects the rising trend of the average temperature of the Tibetan Plateau, while the average precipitation of the Tibetan Plateau is also producing an increasing trend with the increase of temperature. In order to prevent the environmental ecosystem of the Tibetan Plateau from being destroyed by severe climate change under the future influence of global warming, the government should regulate greenhouse gas emissions to ensure that global warming does not worsen.

Toward 2030 CO2 targets – high efficiency engine with gasoline compression ignition technology on a hybrid electric vehicle simulation

The pressure to reduce CO2 and pollutants of internal combustion engine (ICE) powered vehicles is higher than ever. The existing gasoline and diesel engine vehicles face a critical challenge to adjust to these stringent demands. By combining a gasoline like clean fuel with a high efficiency thermodynamic cycle (compression ignition), it is possible to create a powertrain that is clean, both globally and locally, and so breaking the historical trade-off between decreasing CO2 versus pollutants. However, very low vehicle out CO2 cannot be achieved if ICEs are not combined with a hybrid electric powertrain. In this paper, the potential of the gasoline like fuel in compression ignition (GCI) vehicle in combination with hybridization is assessed. Three different hybrid topologies have been theoretically assessed in a first step. Afterwards, the most promising has been deeply analyzed by means of longitudinal vehicle simulation. Here, the corresponding hybrid control strategy is optimized. The battery size has been adjusted as well targeting the optimum capacity when using a HEV instead of a PHEV. The combination of highly efficient GCI engine in combination with such an optimized hybrid topology represents an extreme value regarding CO2 reduction for passenger cars. Such vehicles could contribute largely to the emission targets set for 2030 by the European Commission. In summary, this paper presents engineering solution to comply with future greenhouse gas regulations through advanced engine technology and HEV technology.

Effects of microplastics on greenhouse gas emissions and microbial communities in sediment of freshwater systems

Microplastics can regulate greenhouse gas emissions from environmental systems and affect microbes in the environment. However, the effect of microplastics in freshwater sediment system is still not well studied. In this paper, polyethylene terephthalate (PET) particles with six different diameters of 5–2000 µm were added to freshwater sediment, PET exposing for 90 days was carried out and its effect on greenhouse gas emissions, nutrients cycle and microbial communities were studied. In the 5 µm experimental group, carbon dioxide (CO2) emissions were significantly promoted in the 7–30 days and nitrogen monoxide (N2O) emissions were significantly promoted in the 7 days after cultivation. Microplastics in the range of 300–800 µm significantly promoted CO2 emissions after three days of culture. In addition, microplastics increased the total organic carbon (TOC) content in freshwater sediment and changed microbial diversity, especially increased the microorganisms capable of degrading complex organics such as Saprospiraceae. There was a positive correlation between N2O emission and nitrate (NO3-) content in sediment after 3 days of culture, while greenhouse gas emission was mainly related to TOC content after 90 days of culture. These results showed that microplastics could affect the carbon and nitrogen cycling process of shallow lake ecosystem.