Carbon Balance Analysis Research Articles

Nitrate removal by a novel aerobic denitrifying Pelomonas puraquae WJ1 in oligotrophic condition: Performance and carbon source metabolism

Reducing nitrate contamination in drinking water has become a critical issue in urban water resource management. Here a novel oligotrophic aerobic denitrifying bacterium, Pelomonas puraquae WJ1, was isolated and purified from artificial lake sediments. For the first time, excellent aerobic denitrification capabilities were demonstrated. At a carbon-to‑nitrogen ratio of 5.0, strain WJ1 achieved 100.0 % nitrate removal and 84.92 % total nitrogen removal within 24 h, with no nitrite accumulation. PCR amplification and sequencing confirmed the presence of the denitrification genes napA, nirS, and nosZ in the strain. The nitrogen balance demonstrated that approximately 74.95 % of the initial nitrogen was eliminated as gaseous products under aerobic conditions. Furthermore, carbon balance analysis showed that most electron donors from strain WJ1 were directed towards oxygen, with limited availability for nitrate reduction. A combination of bio-ECO analysis and network modeling indicated that strain WJ1 has robust metabolic capabilities for diverse carbon sources and exhibits high adaptability to complex carbon environments. Overall, Pelomonas puraquae WJ1 removed approximately 45.89 % of the nitrates in raw water, demonstrating significant potential for practical applications in oligotrophic denitrification.

Carbon balance analysis of agricultural production systems in oasis areas

China is the biggest emitter of greenhouse gases (GHGs) in the world, and agricultural GHG emission accounts for nearly a fifth of the total emission in China. To understand the carbon absorption and emission characteristics of agricultural production systems in those arid oasis areas, a typical representative city in northwestern China, Zhangye City, was selected for study.The emission factor method was used to analyze and calculate the characteristics of changing carbon emission dynamics in the whole agricultural production system in Zhangye city region (38,592 km2) from 2010 to 2021.The results revealed that carbon emissions during agricultural planting mainly come from fertilizers, which account for the highest proportion (47.9%) of total carbon emissions in agricultural planting. Animal enteric fermentation emissions from local livestock farming are the main contributor (86%) to GHG emissions. The annual average carbon absorption intensity is 4.4 t C-eq ha−1 for crop and 2.6 t C-eq ha−1 for the agricultural production system. The ratio of total carbon emissions from agricultural production to carbon sequestration of crops is 1:1.7. We find that the total carbon sequestration slightly exceeds its total carbon emissions in the study region, with an annual average of 41% for its sustainable development index. Carbon emissions of the agricultural production system in this oasis area are mainly driven by the livestock industry, mostly CH4 emissions from cattle raising.Reducing the local carbon emissions from the livestock industry, typically the cattle raising, will play a crucial role in reducing carbon emissions from this local agricultural production system and maintaining its net positive carbon balance.

The effect of UV365/Fenton process on the removal of gaseous ethylbenzene in a bubble column reactor

ABSTRACT As volatile organic compounds (VOCs), gaseous ethylbenzene has adverse effects on human health and ecology. Therefore, an effective degradation process is highly desirable. The Fenton process under UV 365 nm was selected as the first option to remove gaseous ethylbenzene in a bubble column reactor. The main parameters for the batch experiments were systematically studied, including H2O2 concentration, [H2O2]/[Fe2+], pH, UV wavelength, UV intensity, gaseous ethylbenzene concentration, gas flow rate, and process stability towards removal efficiency. The optimum conditions were found to be H2O2 concentration of 100 mmol·L−1, [H2O2]/[Fe2+] of 4, pH of 3.0, UV wavelength of 365 nm, UV power of 5 W, gas flow rate of 900 mL·min−1, and gaseous ethylbenzene concentration of 30 ppm, resulting in a removal efficiency of 76.3%. The study found that the Fenton process, when coupled with UV 365 nm, was highly effective in removing gaseous ethylbenzene. The degradation mechanism of gaseous ethylbenzene was proposed in the UV365/Fenton process based on EPR, radical quenching experiments, iron analysis, carbon balance, and GC-MS analysis. The results indicated that •OH played a crucial role in the process.

Exploring the impact of magnetic fields on biomass production efficiency under aerobic and anaerobic batch fermentation of Saccharomyces cerevisiae

In this work, the effect of moderate electromagnetic fields (2.5, 10, and 15 mT) was studied using an immersed coil inserted directly into a bioreactor on batch cultivation of yeast under both aerobic and anaerobic conditions. Throughout the cultivation, parameters, including CO2 levels, O2 saturation, nitrogen consumption, glucose uptake, ethanol production, and yeast growth (using OD 600 measurements at 1-h intervals), were analysed. The results showed that 10 and 15 mT magnetic fields not only statistically significantly boosted and sped up biomass production (by 38–70%), but also accelerated overall metabolism, accelerating glucose, oxygen, and nitrogen consumption, by 1–2 h. The carbon balance analysis revealed an acceleration in ethanol and glycerol production, albeit with final concentrations by 22–28% lower, with a more pronounced effect in aerobic cultivation. These findings suggest that magnetic fields shift the metabolic balance toward biomass formation rather than ethanol production, showcasing their potential to modulate yeast metabolism. Considering coil heating, opting for the 10 mT magnetic field is preferable due to its lower heat generation. In these terms, we propose that magnetic field can be used as novel tool to increase biomass yield and accelerate yeast metabolism.

Spatiotemporal differentiation of carbon budget and balance zoning: Insights from the middle reaches of the Yangtze River Urban Agglomeration, China

Urbanization has substantially changed land use and led to local growth and an overall imbalance in carbon emissions. Scientific analysis of carbon emissions from land use (CELU) and exploration of carbon balance zoning can provide useful references for regional low-carbon land use management in urban agglomerations. This study analyzed the spatiotemporal dynamics of CELU based on land use and socioeconomic data, and utilizing the emission coefficient method. The economic contribution coefficient of carbon emissions (ECC) and Ecological Support Coefficient of carbon emissions (ESC) was used as the basis for developing carbon balance zoning, and the main function positioning of counties was used to combine with carbon balance zoning. Subsequently carbon balance partitions with determinants across 190 counties in the Middle Reaches of the Yangtze River Urban Agglomeration (MRYRUA) was obtained. We found that the net carbon emissions from land use in MRYRUA increased from 1.242 to 4.049 million tons, showing a clear upward trend. Notably, the Gini coefficients of carbon emissions and sinks of the MRYRUA were both higher than 0.4, and the pressure on the regional carbon balance intensified. In addition, based on the carbon balance analysis, MRYRUA was divided into five types: low-carbon economic zones, low-carbon optimization zones, carbon intensity control zones and high-carbon optimization zones. These zones were used to combine with the main function positioning, and finally got 11 types of zoning results. In response, this study proposes different low-carbon land-use optimization strategies based on the carbon budget and comprehensive development characteristics of different zones.

PFAS degradation by anodic electrooxidation: Influence of BDD electrode configuration and presence of dissolved organic matter

Per- and poly-fluoroalkyl substances (PFAS) pose substantial environmental and human health risks. Electrochemical oxidation technology is a promising large-scale solution for PFAS degradation due to its simplicity and minimal waste generation. This study investigated the electrochemical performance of boron-doped diamond (BDD) electrodes in degrading PFAS using a recirculation cell with plate and mesh electrodes. The study found that increasing the current density from 6.4 mA/cm2 to 40 mA/cm2 resulted in a transition of the reaction rate from pseudo-first-order toward zero-order kinetics. The stepwise degradation mechanism and the formation of intermediate products were also explored. Carbon and fluorine molar balance analysis revealed that the missing intermediates do not contain fluoride atoms in their molecular formula. The shape and surface of the electrodes had a significant impact on their performance, in particular, improving the degradation of the most recalcitrant perfluorobutanoic acid. The influence of different fractions of dissolved organic matter (DOM) on perfluorohexanoic acid degradation shows that overall, DOM does not significantly inhibit its degradation. Some inhibition was observed in the presence of DOM enriched in carbohydrates, organics that are known to exert strong interaction properties with organic and inorganic surfaces. The synergistic effect of direct anodic oxidation and indirect degradation by reactive radical species enables the decomposition of both DOM and PFAS. Finally, high removal percentages of short (up to 96 %) and long-chain PFAS (up to 99 %) were obtained using BDD electrooxidation cells combining plate and mesh electrodes when treating reverse osmosis concentrate containing PFAS.

Elucidating the role of ferric chloride on carbon capture from low-strength municipal wastewater in high-rate activated sludge process: Parameter optimization and crucial mechanism

To enhance organics capture efficiency from low-strength municipal wastewater of China, FeCl3 enhanced high-rate activated sludge (FC-HRAS) process was established in this work. Effects of sludge concentration and FeCl3 dosage on carbon capture in FC-HRAS were investigated. The optimum sludge concentration of 2.0 g/L and FeCl3 dosage of 30 mg Fe/L were obtained, with total COD removal efficiency of 76.8%. Carbon balance analysis showed that FC-HRAS increased organics capture proportion by 91.8% while reducing loss from oxidative metabolism compared to HRAS. The potential mechanism of enhanced carbon capture for FC-HRAS was further explored. Adding Fe(III) caused coagulation of organics by increasing the Zeta potential in wastewater. Impacted by charge neutralization “compression” and coagulation floc “encirclement”, sludge particle sizes decreased, leading to increases of internal surface area and adsorption site of sludge for binding with bacteria; it facilitated the biological flocculation of FC-HRAS. Meanwhile, Fe(III) binding with proteins in EPS induced formation of “protein shell – β polysaccharides kernel” sludge structure and reduction of sludge negative charge, which intensified sludge stability and agglomeration. These factors explained the increase in organics capture proportion. The decrease in metabolism loss of organics could be attributed to the increase in organics transfer resistance in sludge EPS and selective elimination of heteromorphic bacteria (e.g., denitrifiers) in sludge. This work provided guidance for energy-neutral and cost-saving wastewater treatment in China.

Spatiotemporal characteristics and zonal analysis of carbon balance in county-level regions: case study of Jiangsu Province

In China, county-level regions play a pivotal role in achieving dual carbon goals. In this study, we analyzed the spatiotemporal characteristics of carbon balance coefficients for counties in Jiangsu Province from 2000 to 2021. The logarithmic mean Divisia index decomposition method explored the factors influencing county-level carbon balance. The findings indicated that CO2 emissions in Jiangsu Province increased from 192 million tons in 2001 to 637 million tons in 2011 and exhibited a small fluctuation from 2012 to 2021. A “higher in the south, lower in the north” distribution pattern emerged, with high CO2 emission areas concentrated in the economically developed south. Vegetative carbon sequestration increased from 142 million tons in 2000 to 171 million tons in 2021 with a “higher boundary and lower at the center” distribution pattern. High carbon sequestration areas were mainly in regions with abundant natural resources and vegetation. The number of counties experiencing carbon imbalance rose from 63 in 2000 to 95 in 2021, with a spatial distribution similar to high carbon emissions. Economic development and urbanization accelerated carbon imbalance, whereas technological advancement and reduced regional carbon fixation pressure effectively alleviated it. Pursuing of dual carbon goals can be supported by reducing emissions and increasing carbon sinks.

Spatial difference of carbon budget and carbon balance zoning based on land use change: a case study of Henan Province, China.

Land use change is one of the key reasons for the rise in global carbon emissions. Incorporating practical methods for carbon governance into the major strategic decisions of countries around the world is important for controlling carbon emissions. This study aims to carry out a regional land use carbon budget assessment and build a carbon balance zoning optimization framework. As a result, China will be better able to implement low-carbon strategies and reach carbon peaking and carbon neutrality. Using the data of land use and energy consumption for Henan Province from 2000 to 2020, a carbon budget assessment system was constructed. According to the analysis of the geographical distribution of carbon budget, an evaluation system was developed and a carbon balance partition was established from the natural, economic, ecological and resource structure. A regionally differentiated development strategy was proposed. The findings revealed that: (1) Land use carbon emissions of Henan Province reflected a significant increasing trend, while the variation in carbon absorption of land use was stable. Carbon emissions increased by 87,120.25×104 t in 2020 compared to 2000, but the carbon absorption remained at approximately 1735×104 t over the years and there was an overall state of carbon deficit. (2) The geographical distribution of carbon emissions in Henan Province was characterized by higher in the central part and lower in the surroundings, and the distribution of carbon absorption was higher in the west and lower in the east. The distribution pattern was closely related to the level of land use and the structure of energy consumption. (3) From the carbon balance analysis, the 158 counties in Henan Province were divided into four carbon balance functional areas, namely the carbon sink functional area, low-carbon development area, carbon intensity control area, and high-carbon optimization area. Different optimized development strategies were proposed for each functional area.

An appraisal of the utility of biochar in a rotation involving tobacco–rice in southern China

AbstractThe employment of biochar in crop production can not only improve soil quality, but also helps the field ecosystem to fix carbon and reduce emissions. Although the benefits of their application in crop production have been more and more confirmed, it is not clear when it comes to the acidic soil of tobacco and rice rotation. A tobacco–rice rotation experiment was conducted in southern China to probe the application value of biochar under these conditions. Three biochar application rates were employed in this experiment. BC0 (without biochar), BC25 (25 t ha−1), and BC50 (50 t ha−1). The findings show that biochar significantly boosted soil fertility and crop yields. Meanwhile, the soil organic carbon of tobacco rice rotation field with biochar increased by 31.76%. After a whole growth period of tobacco and rice, the cumulative emission reduction of CO2 and N2O from the soil by biochar were 15,944 kg ha−1 and 1810 g ha−1, respectively. The use of biochar not only significantly improved the bacterial diversity of tobacco and rice rotation soil, but also altered the original microbial community structure. The profusion of Proteobacteria and Acidobacteria was reduced and the abundance of Actinobacteria and Bacteroidetes was enhanced in the treatments with biochar. Among them, Sphingomonadales, Planctomycotes, and Ktedonobacteria, which are beneficial to plant growth and soil health, have become key phylotypes. The carbon balance analysis data show that the net carbon sequestration of the two treatments with biochar is positive, while that of the treatment without biochar is negative. In terms of economic benefit, the application of biochar increased the average of 2.055 CNY kg−1 consumed energy (CE) in the whole tobacco–rice rotation system. The ecological benefit was 0.51 kg C kg−1 CE. In conclusion, biochar can be effectively used in the practice of tobacco–rice rotation and acidic soil improvement in southern China.

Analysis and prediction of carbon balance in production-living-ecological space of Henan Province, China.

As the carrier of human economic activities, the change of territorial space affects the level of regional carbon balance. Therefore, with regional carbon balance as the goal, this paper proposed a framework from the perspective of production-living-ecological space and took Henan Province of China as a study area for empirical research. First, the study area established an accounting inventory that considers nature, society, and economic activities to calculate carbon sequestration/emission. Then, the spatiotemporal pattern of carbon balance was analyzed by ArcGIS from 1995 to 2015. Later, the CA-MCE-Markov model was used to simulate the production-living-ecological space pattern in 2035, and carbon balance in three future scenarios was predicted. The study showed that from 1995 to 2015, the living space gradually expanded, and the aggregation rose while the production space decreased. Carbon sequestration (CS) was less than carbon emission (CE) and presented an unbalanced state of negative income in 1995, while CS exceeded CE and showed a positive income imbalance in 2015. In 2035, living space has the highest carbon emission capacity under natural change scenario (NC), while ecological space has the highest carbon sequestration capacity under ecological protection scenario (EP), and production space has the highest carbon sequestration capacity under food security scenario (FS). The results are crucial for understanding the carbon balance changes in territorial space and supporting regional carbon balance goals in the future.

"National carbon source" or "national carbon sink"?Based on the carbon balance analysis of Wuyi Mountain National Park

"National carbon source" or "national carbon sink"?Based on the carbon balance analysis of Wuyi Mountain National Park

Respiratory electrogen Geobacter boosts hydrogen production efficiency of fermentative electrotroph Clostridium pasteurianum

Electrogens and electrotrophs are microorganisms that generate and consume electricity in a bioelectrochemical system, respectively. However, the influence of respiratory electrogen Geobacter on the hydrogen production efficiency of fermentative electrotroph Clostridium pasteurianum remains unclear. Herein, cocultures with Geobacter sulfurreducens and C. pasteurianum were successfully established during glucose fermentation. Compared with those in C. pasteurianum monoculture alone, the maximum rate and yield of hydrogen production in the coculture increased by 122.2% and 28.92%, respectively. Meanwhile, substrate conversation efficiency elevated by 50.6%. The acetic and butyric acid fermentation pathways in the cocultures were also promoted relative to those in the monoculture. Carbon and electron balance analysis also unraveled that acetate production in syntrophic coculture accounted for approximately-two times more carbon and electron contributions than that in the monoculture. A direct manner mediated by pili-like structures or cell contacts was built between the two electroactive bacteria during the electric syntropy. Extracellular electron inputting from G. sulfurreducens shifted the fermentative pattern of C. pasteurianum, which resulted in an enhanced acetic acid fermentation pathway accompanied by a higher hydrogen yield. These findings provide new insights into electric syntrophy between respiratory electrogenic G. sulfurreducens and fermentative electrotrophic C. pasteurianum. A new strategy for hydrogen enhancement by coculturing hydrogen-producing electrotrophic bacteria with electrogenic microorganisms is also explored.

Экологическая оценка сезонной динамики почвенных потоков CO2 и содержания гумуса дерново-подзолистых почв на склоновой катене лесопарка при разных уровнях рекреационной нагрузки

The article presents the results of monitoring the spatial and temporal variability of the main diagnostic parameters of the humus state (humus content, soil CO2 fluxes and carbon stock) of Podzoluvisols in conditions of typical for the northern part of Moscow urban forest “Forest Experimental Station” of the Russian State Agrarian University - Moscow Timiryazev Agricultural Academy, formed 160 years ago on the basis of a natural forest area, with the introduction of monocultural plantings of various tree species typical for subzones of southern taiga and mixed forests of the European part of Russia and Western Siberia. As the main unregulated and regulated factors of the spatio-temporal variability of the humus state of the studied soils, the following ones are considered: (a) their position in the mesorelief (the summit of the gentle moraine hill – the middle part of the slope – the lower part (foot) of the slope); (b) the forest composition; (c) the level of recreational load (estimated by the severity of the path network); (d) the state of the herbage (estimated by the index of the projective cover); (e) the topsoil bulk density; (e) the topsoil moisture; (g) the topsoil temperature. Three levels of recreational load are considered: minimal (background), medium and strong. Soil samples were taken during three seasons in 2021: in spring, summer and autumn – from a depth of 0-5, 5-10 and 10-15 cm. The intensity of the soil CO2 flux, temperature and soil moisture were determined 2 times a month. The content of organic carbon in the topsoil and the topsoil bulk density – once a month. A mobile infrared gas analyzer (IRGA) Li-820 was used to analyze the CO2 flux. For statistical data analysis – Excel and SPSS programs. The conducted studies revealed a pronounced seasonal dynamics of soil CO2 fluxes and the content of humus (soil organic matter) in the upper horizons of the studied soils – with a clear differentiation according to the mesorelief forms and the level of recreational load. Summer maxima of CO2 fluxes reach 35-40 g/m2 per day, and by the end of October they fall in 3-5 times. The humus content in the topsoil horizons (A1 – A1A2 – A2) within the total analyzed thickness of 15 cm in most cases after the April maximum significantly decreases (by 0.5–0.7%) to the seasonal minimum in August. With an increase in recreational load, on the contrary, there is a gradual decrease in the humus content by 10-20 relative percent. The average intensity of soil CO2 emissions increases downhill by 5-7 g/m2 per day and decreases with increasing recreational load by 5-10 g/m2 per day. The established regularities significantly clarify the existing ideas about the spatial and temporal variability of the diagnostic parameters of the humus state of Podzoluvisols in an urban forest park with a pronounced recreational load and allow for a more reasonable selection of background environmental monitoring objects with an analysis of greenhouse gases and soil carbon balance. Keywords: ECOLOGICAL ASSESSMENT, SEASONAL DYNAMICS, SOIL CO2 FLUXES, HUMUS CONTENT, PODZOLUVISOLS, SOIL SPATIAL AND TEMPORAL VARIABILITY, SOIL CARBON STOCKS, CATENA, FOREST PARK, MOSCOW, RECREATIONAL LOAD

Carbon balance analysis of sewage sludge biochar-to-soil system

Converting sewage sludge (SS) into biochar via pyrolysis is proposed as a prospective strategy for recycling nutrients and reducing environmental risks. Yet, from the perspective of carbon (C) balance the viability of pyrolyzing SS still remains unclear. Here we quantified the C footprint of the whole process from raw SS pyrolysis to final disposal of SS-derived biochar (SSB) using life cycle assessment based on a 20-tonne industrial pyrolysis furnace and field experiments. Results indicated that about 0.101 tonnes of direct CO2 equivalent (CO2e) (from N-containing organic compounds in SS) plus 1.506 tonnes of indirect CO2e (from energy consumption and dewatering agents) were emitted for each tonne of dry SS treated during its dewatering and pyrolysis processes, and at least 0.252 tonnes of CO2e were sequestered as stable C in SSB, depending on the final application route of SSB. In contrast, the net C emissions from traditional SS treatments amounted to at least 2.432 tonnes of CO2e per tonne of dry SS under the similar scenarios. Converting SS into SSB thus showed great advantages in C balance over the traditional treatments of SS. Sensitivity analyses indicated that the moisture and C contents of SS and the usage of dewatering agents were the key factors affecting C balance in the SSB-to-soil system. These findings highlight the C sequestration potential of pyrolysis and provide important support for the optimization and management of SS treatment.

Kinetic modeling of binary mixture of butyraldehyde and acetone with generated by-products in photocatalytic oxidation reactor

This research reports the development of a kinetic model to predict binary mixture degradation and by-product generation in a continuous flow Photocatalytic Oxidation (PCO) reactor. Butyraldehyde and acetone were chosen as a binary VOC mixture to validate the model using experiments conducted with a photocatalyst (TiO2 coated on silica fibers) under various concentration levels (0.1–1 ppm), concentration ratios of target compounds in the mixture (0.5–2), relative humidity levels (17–70%), irradiations (7–23.5 W/m2), and airflow rate (10–30 L/min). Formaldehyde, acetaldehyde, propionaldehyde, butyric acid, propionic acid, and acetic acid were detected as by-products, in which aldehydes had a higher quantity. Carbon balance analysis showed that butyraldehyde and binary mixtures mineralized into carbon dioxide at rates of 19% and 12.8%, respectively. Also, 24% of butyraldehyde and 10% of binary mixture were converted to by-products. Among three proposed scenarios for PCO reaction rate of butyraldehyde, the one including conversion of butyraldehyde directly towards propionaldehyde, acetaldehyde, and formaldehyde, provided the most accurate rate model (R2 = 0.98). Due to its faster reaction rate, butyraldehyde demonstrated a higher degradation efficiency than acetone in the binary mixture. At a constant butyraldehyde concentration, lowering the ratio of butyraldehyde/acetone to 0.5 resulted in the reduction of removal efficiency of butyraldehyde and an increase in concentration of acetaldehyde in air than other by-products. Conversely, enhancing this ratio to 2, led to improved removal efficiency of both butyraldehyde and acetone in the mixture and higher concentration of formaldehyde. Increases in air relative humidity level and velocity resulted in an increase in the outlet concentration of challenge compounds but reduced the formation of all by-products. However, raising the irradiation increased the degradation efficiency of butyraldehyde and binary mixture and, consequently, elevated the formation of by-products. The developed model was capable of properly predicting the concentration of the challenge compounds and their by-products in a binary mixture at different operating conditions.

基于固碳服务供需视角的河南省碳平衡研究

PDF HTML阅读 XML下载 导出引用 引用提醒 基于固碳服务供需视角的河南省碳平衡研究 DOI: 10.5846/stxb202108302449 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（42171261）；碳中和与国土空间优化重点实验室开放基金项目（2021CNLSO2001） Carbon balance from the perspective of supply and demand of carbon sequestration services in Henan Province Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:土地利用变化影响陆地系统碳循环过程。在实现碳中和目标的背景下，分析区域碳平衡，优化土地利用结构具有现实意义。以河南省为例，以1 km网格为单元，应用InVEST碳固存模块、IPCC碳排放核算、人口密度法等方法，研究1995、2005、2015年区域碳平衡的时空变化。结果表明，研究区固碳服务的供需量与土地利用类型密切相关。固碳服务的供需在空间存在错配关系，即需求高的地区通常具有较低的供给。研究时段内，研究区的总碳固量逐年下降，总碳排放量逐年增加，研究区碳平衡表现为整体向好，局部恶化的情况。在碳平衡分析的基础上提出了空间优化利用建议，可为未来国土空间规划碳平衡目标的实现提供参考。 Abstract:Land use and land cover change mainly affect the carbon cycle process in the terrestrial ecosystem. In the context of achieving carbon neutrality, it is of practical significance to analyze regional carbon balance and optimize land use structure. Taking 1 km grid as the unit and Henan Province as an example, this paper used InVEST carbon sequestration module, IPCC carbon emission accounting method, and population density method to study the spatio-temporal changes of regional carbon balance in 1995, 2005, and 2015. The results show that the supply and demand of carbon sequestration services in the study area are closely related to land use types. There is a spatial mismatch between supply and demand of carbon sequestration services, that is, areas with high demand usually have low supply. During the study period, the total carbon sequestration in the study area decreased year by year, while the total carbon emissions increased year by year. The carbon balance in the study area showed an overall positive trend, while local deterioration. Based on the analysis of carbon balance, some suggestions on spatial optimization are put forward, which can provide reference for the realization of carbon balance target of national spatial planning in the future. 参考文献 相似文献 引证文献

Relationship between lipopeptide biosurfactant and primary metabolite production by Bacillus strains in solid-state and submerged fermentation

The relationship between lipopeptide and primary metabolite production by Bacillus spp. in solid-state fermentation (SSF) and submerged fermentation (SmF) was evaluated. Four wild-type strains and one mutant strain (unable to develop biofilm) were assessed in SSF and SmF, using a defined medium and polyurethane foam as inert support for SSF. Strain ATCC 21,332 in SSF presented the highest lipopeptide production. The wild-type strains revealed higher lipopeptide and biomass production and lower synthesis of primary metabolites in SSF than in SmF. However, the mutant strain showed a slightly higher production of primary metabolites in SSF than in SmF. Carbon balance analysis showed that the carbon flux was mainly directed to lipopeptides in SSF, whereas in SmF, it was directed to the production of primary metabolites and the carbon flux to lipopeptides is inversely related to primary metabolites in both types of cultures.

Unravelling CO2 capture performance of microalgae cultivation and other technologies via comparative carbon balance analysis

Microalgae cultivation, absorption, adsorption, and membrane separation are widely applauded as promising technologies to sequester CO2 from flue gas. Herein, comparative carbon balance was used to elucidate their CO2 capture performance in the aspects of CO2 emission rates (direct, indirect, total, and net), CO2 removal efficiencies (apparent and actual), and CO2 removal rate per power input ratio. Screening criteria for effective CO2 capture system rule out energy-intensive sorption processes, put forward low energy membrane separation, and disclose alterable competency of microalgae cultivation. For CO2 capture from flue gas, microalgae (Chlorella vulgaris) cultivation in open raceway ponds was only inferior to membrane separation. To improve microalgal CO2 capture, the sensitivity analysis was performed by replacing original microalgae species (C. vulgaris) or cultivation system (open raceway pond). The microalgal CO2 capture in open raceway ponds became worse following the substitution of C. vulgaris with alternatives (Botryococcus braunii, Chlorella kessleri, Chlorella pyrenoidosa, Scenedesmus obliquus, Spirulina sp., or Tetraselmis suecica). For microalgal (C. vulgaris) CO2 capture, the competent cultivation systems included open raceway pond and airlift photobioreactor, while the bubble column, flat panel, or tubular photobioreactors were classified as non-competent systems. In short, microalgal (C. vulgaris) CO2 capture was technically feasible in open raceway pond or airlift photobioreactor; further, the use of airlift photobioreactor was preferred for better CO2 capture and microalgae biomass production. Due to the necessity of a huge working volume, the low scalability of microalgae cultivation could hamper the industrial application of microalgal CO2 capture from flue gas.

Kinetic modeling and reaction mechanism of toluene and by-products in photocatalytic oxidation reactor

Photocatalytic oxidation (PCO) is an innovative and promising technology for removing VOCs from indoor environment. However, partial oxidation of reactants generates by-products that could be more harmful to human health than parent compound. This paper presents the development of a by-products predictive model for the estimation of generated by-products based on the degradation reaction pathway of toluene in PCO. A one-dimensional mathematical model by considering the axially dispersed plug flow and Langmuir-Hinshelwood (L-H)-based reaction rate as well as linear source spherical emission (LSSE) model for the irradiation distribution on the media surface was developed for the prediction of the by-products concentration. Toluene was tested in a continuous flow PCO reactor with a commercial PCO filter under various operating conditions; concentrations (0.05–1 ppm), relative humidities (17–67%), flow rates (10–30 L/min), and irradiance (7–23.5 W/m2). Several by-products from various chemical groups, including aldehyde, ketone, alcohol and light acid, were identified by analytical instruments. Aldehydes were the major by-products of toluene in PCO, in which light aldehydes (acetaldehyde and formaldehyde) had a higher concentration among others. The result of curve fitting using the proposed model showed a high accuracy of the model (with R-squared greater than 0.98) for parameters estimation. Kinetic analysis of toluene indicated that the rate coefficients followed the order of benzaldehyde > propionaldehyde > acetaldehyde > formaldehyde. Benzaldehyde and propionaldehyde had a greater value of the kinetic coefficient in PCO because of higher adsorption tendency towards TiO2. Changes in operating conditions highly affected generation of by-products and the developed model could predict the concentration of toluene and the by-products with acceptable accuracy. The carbon balance analysis at residence time of 0.24 s showed 16.6% of toluene mineralized into carbon dioxide and it increased at longer residence time. The health risk index (HRI) analysis of toluene and its by-products was performed and found out that formaldehyde was the most influential pollutant on HRI due to very low recommended exposure limit and higher generated concentration.