Search Results (3,026)

The kinetic study of micro-electrolysis biotechnology not only determines the removal efficiency of a micro-electrolysis process but also influences the optimal design of a system. This paper investigates the relationship between electric field strength, pollutant degradation rate, and biofilm thickness by constructing a microporous biofilm model for pollutant removal. Additionally, the study derives equations linking electric field strength to reaction rate, pollutant effluent concentration, and biofilm thickness under both high and low pollutant influent concentrations. This work bridges the gap between macroscopic processes and periplasmic mechanisms, enhancing our understanding of pollutant removal mechanisms and facilitating process optimization. It also provides theoretical support for the sustainable development of micro-electrolysis biotechnology. Future research will focus on experimental validation and the optimization of model accuracy and flexibility to accommodate diverse treatment conditions. Full article

The wattle tree (Acacia mearnsii) is gaining importance as an exotic species in northwestern Ethiopia, providing ecological, environmental, and economic benefits, especially for fuelwood and charcoal production. This study aimed to investigate the effect of tree spacing on the growth and biomass of wattle trees. The study employed a randomized complete block design with three replications across three spacing treatments (0.5 m × 0.5 m, 1 m × 1 m, and 1.5 m × 1.5 m) in the Fagita district. Tree height and diameter measurements were taken at 12, 18, and 30 months post-planting from stands established in 2021. The results showed significant differences in tree height among the spacing treatments at 18 and 30 months. The closest spacing (0.5 m × 0.5 m) yielded the highest average tree heights of 32.12 cm, 84.86 cm, and 302.98 cm at 12, 18, and 30 months, respectively. At 18 months, the largest average diameter (1.22 cm) was found in the narrowest spacing (0.5 m × 0.5 m), whereas at 30 months, the widest spacing (1.5 m × 1.5 m) recorded the largest diameter (1.51 cm). Throughout the study, height, diameter, and average aboveground biomass exhibited an inverse relationship with spacing, with this effect diminishing as trees aged. Tree spacing significantly impacted average aboveground biomass at 18 months, with the densest spacing (0.5 m × 0.5 m) yielding the highest average aboveground biomass (1.97 kg at 18 months and 2.41 kg at 30 months). Average aboveground biomass increased as the trees matured. These findings suggest that closer spacing of A. mearnsii can enhance biomass production, positioning it as a promising candidate for energy generation. Leveraging these insights can optimize resource utilization while supporting global energy demands and reforestation initiatives aimed at carbon sequestration. Full article

The application of mineral fertilizers can effectively enhance crop yields. However, this potential benefit may be diminished if the use of mineral fertilizers leads to a substantial decline in soil organic carbon (SOC) and an increase in soil greenhouse gas (GHG) emissions. This study aimed to determine the optimal fertilizer combinations and rates for improving SOC and maize yield while reducing GHG emissions in the semi-arid uplands of Kenya. Data were collected from five different fertilizer treatments (N50, N100, N150, N100+manure, and N100+straw) compared to a control (N0) in a long-term experimental field, which was used to run and validate the DNDC model before using it for long-term predictions. The results showed that the combination of mineral fertilizer and straw resulted in the highest SOC balance, followed by that of fertilizer and manure. All fertilized treatments had higher maize grain yields compared to low-fertilizer treatment (N50) and control (N0). Daily CO₂ fluxes were highest in the treatment combining mineral fertilizer and manure, whereas there were no significant differences in N₂O fluxes among the three tested treatments. The findings of this study indicate that the judicious application of mineral fertilizer, animal manure, and straw has great potential in enhancing SOC and maize yields while reducing GHG emissions, thereby providing practical farming management strategies in semi-arid Kenya. Full article

Evaluating SOC lability is crucial for sustainable agriculture policies and environmental quality. This study assessed the impact of well-stocked forest cover on SOC pools and lability compared to shrubby soil. Geo-referenced soils under Red pine (Pinus brutia), Black pine (Pinus nigra), Cedar (Cedrus libani), Fir (Abies cilicia), Juniper (Juniperus excelsa), Oak (Quercus L.), Carob (Ceratonia siliqua), and degraded shrubs were collected from a depth of 0 to 30 cm in the Seyhan River Basin, Mediterranean Turkey. The analysis of soil organic carbon (SOC), soil AC (active carbon), and PC (passive carbon) were analyzed to understand soil carbon management across diverse vegetation types. Juniper forests have the highest SOC (27.98 g/kg) and PC (27.35 g/kg), followed by Cedar (SOC: 27.64 g/kg, PC: 27.05 g/kg) and Fir (SOC: 26.44 g/kg, PC: 25.85 g/kg). Shrubby areas have the lowest SOC (4.06 g/kg) and PC (3.61 g/kg). The Oak soil had the highest CLI (1.16), suggesting a relatively higher proportion of labile carbon than other forests. CPI indicates forests have a greater carbon storage capacity (1.09) compared to shrublands (0.18), with forests also having a higher CMI (0.83). The findings emphasize the critical role of forests, especially Juniper forests, in carbon sequestration and climate change mitigation within the Seyhan River Basin in Turkey. Full article

Microalgae possess the remarkable ability to autotrophically grow, utilizing atmospheric carbon dioxide (CO₂) for photosynthesis, thereby converting solar energy into chemical energy and releasing oxygen. This capacity makes them an effective tool for mitigating industrial CO₂ emissions. Mathematical models are crucial for predicting microalgal growth kinetics and thus assessing their potential as industrial CO₂ sequestration agents under controlled conditions. This study innovatively evaluated the effect of continuously supplying CO₂ from winemaking processes on microalgal cultivation and biomass production, demonstrating a novel approach to both carbon capture and the valorization of a valuable by-product. To analyze microalgal growth kinetics, three mathematical models were employed: Logistic, First Order Plus Dead Time, and Second Order Plus Dead Time. Optimal parameter values for each model were identified using a hybrid search algorithm developed by our research group. First, an integrated microvinification system was established, utilizing two microalgae species, Chlorella spp. (FAUBA-17) and Desmodesmus spinosus (FAUBA-4), in conjunction with yeast fermenters. This system facilitated a comparison of the biomass kinetics of these two microalgae species, selecting Chlorella spp. (FAUBA-17) as the most suitable candidate for subsequent cultivation. A pilot-scale vertical column photobioreactor was then constructed and installed at the Casimiro Wines boutique winery in Angaco, San Juan, Argentina. After 15 days of operation within the photobioreactor, a biomass growth of 1.04 ± 0.05 g/L and 1.07 ± 0.1 g/L was obtained in Photobioreactors 1 and 2, respectively. This novel integrated approach to CO₂ capture in the winemaking process is unprecedented. These findings highlight the potential for producing high-value microalgal biomass, promoting the establishment of a local biorefinery and fostering a circular economy and sustainable social development. Full article

Ecosystem services (ESs) are extremely important, specifically in urban areas. Urban forests, even representing a pivotal role in global sustainability, have been converted into different human-modified landscapes. This paper aims to analyze the ES provided by the urban areas of 25 cities of the Atlantic Forest in Brazil. We used i-Tree Canopy v.7.1 to classify the land use. We quantified the monetary benefits of the urban vegetation and used socioeconomic variables (i.e., total population, population density, Human Development Index (HDI), and Gross Domestic Product (GDP) per capita) to analyze if the ecosystem services or the land uses are associated with this. Our data reveal that together, the cities studied sequester a significant total of 235.3 kilotonnes of carbon and a substantial 864.82 kilotonnes of CO₂ Equivalent (CO₂ Equiv.) annually. Furthermore, together, they also store a total of 4861.19 kilotonnes of carbon and 17,824.32 kilotonnes of CO₂ Equiv. We found out that the average monetary estimate of annual carbon sequestration was USD 3.57 million, while the average stored estimate was USD 73.76 million. Spearman’s correlogram showed a strong positive correlation between density and the percentage of impervious cover non-plantable no trees (IN) in urban areas (p < 0.001). IN was also positively correlated with HDI (p = 0.01), indicating that urban areas with higher HDI tend to have larger impervious areas. Our data suggest essential insights about the ecosystem services provided by urban areas and can serve as significant findings to drive policymakers’ attention to whether they want to provide more ecosystem services in cities. Full article

Urban agriculture is increasingly recognized as a strategy for enhancing sustainability and well-being in urban areas, mainly through circular economy principles. This study investigates residents’ perspectives from three major cities in western Romania—Arad, Timișoara, and Oradea—on the implementation and benefits of urban agriculture. The main goal was to identify differences in opinions regarding urban agriculture’s potential to improve biodiversity conservation, enhance carbon dioxide retention, and reduce synthetic compound usage. The research also explored community development through circular economy practices and tools local authorities could use to promote urban agriculture. A survey of 573 respondents utilized variance analysis and the Tukey test to reveal significant opinion differences among residents. The findings showed notable variations in views on biodiversity conservation and community development benefits but no significant differences in opinions on carbon dioxide capture or synthetic chemical use. Residents of Timișoara and Oradea expressed more favorable views on urban agriculture than those in Arad. Participants emphasized the importance of free land allocation and sustainable practices for successful urban agriculture implementation. This study offers valuable insights for policymakers and contributes to the understanding of urban sustainability and the role of urban agriculture in supporting circular economy principles. Full article

Urban green spaces (UGS) are crucial urban elements that serve as direct carbon sequestration and contribute to indirect carbon emission reduction. Accurately calculating the carbon density of urban green spaces allows for scientific planning and design, thereby advancing efforts toward achieving carbon neutrality. This study has developed a workflow for estimating carbon density in urban green spaces through point cloud measurements and model simulations, using the UGS in the Beijing Main District as a case study. From the sample level, a calculation methodology was constructed based on the point cloud technology-model simulation method, which can obtain the carbon density at the plant level and the sample level. At the UGS level, remote sensing inversion was utilized to map the carbon density of urban green spaces. Ultimately, the research calculated and compared carbon density at different scales, including the carbon density of individual plants, the carbon density of sample plots, and the carbon density of various types of urban green spaces. It was found that the carbon density of trees in UGS was 9.87 kg/m², while those of shrubs and herbaceous plants were 13.20 kg/m² and 0.11 kg/m². In urban green spaces, the carbon densities of the tree and herb layers were slightly lower than those in natural ecosystems, whereas the carbon density of the shrub layer was significantly higher. This highlights the substantial potential and value of shrubs in carbon sequestration and carbon storage. The average carbon density of all UGS types was 9.76 kg/m², with the following descending order: Neighborhood Parks (10.31 kg/m²) > Attached Green Spaces (7.22 kg/m²) > Regional Parks (5.75 kg/m²). Based on these findings, the study proposed optimization strategies for different UGS types, focusing on high carbon-density plant community optimization. The goal is to provide a theoretical foundation for carbon storage calculations and plant arrangements in future UGS construction. Full article

Wood construction is often proposed to reduce the construction sector’s greenhouse gas emissions due to its carbon sequestration potential. However, forestry significantly impacts natural water flows and increases water use—a critical concern in Chile. This study evaluates the water footprint of wood construction in Chile, considering direct and indirect water consumption under various scenarios. An input–output model was developed to quantify economic interactions, incorporating a new wood-construction sector based on data from a model house. An environmental extension matrix was also created to account for blue water (groundwater and surface water extraction) and green water (rainwater absorbed from soil) consumption. Future scenarios for the residential building sector were defined based on different growth rates for wood-based construction and current construction methods, and the model was resolved using the scenarios as demand vectors. The results indicate that wood construction’s water footprint is 2.38–2.47 times higher than conventional construction methods, with over 64% linked to forestry’s green water demand. By 2050, increased wood construction could raise the sector’s total water footprint by 30.0–31.8%. These findings underscore the need to assess water consumption as a critical sustainability parameter for wood construction and highlight the value of tools like the water footprint to guide decision-making. Full article

The semi-humid evergreen broadleaved forest (SEBF) is the zonal vegetation type of western subtropical regions in China. Under human and natural disturbance, the area of SEBFs is severely shrinking, with remaining fragments scattered across mountains of the Central Yunnan Plateau. To explore the mechanisms of community assembly and species maintenance in the severely fragmented SEBFs, we selected three sites—Jinguangsi Provincial Nature Reserve, Huafoshan Scenic Area, and Qiongzhusi Forest Park—across the range of this vegetation type, and sampled a total of 42 plots of forest dominated by Castanopsis orthacantha Franch., the most widely distributed community type of SEBFs. We compared the species richness and composition of the communities of different age classes, employed the net relatedness index to characterize the phylogenetic structure of communities, and used Mantel tests and partial Mantel tests to quantify the impacts of spatial distance, age class, and habitat factors (including climate, topography, and soil) on species turnover across different spatial scales (i.e., intra- and inter-site) for trees, shrubs, and herbs, respectively. The results indicated the following: (1) In the young stage, the C. orthacantha communities exhibited a species richness statistically lower than those in middle-aged and mature communities. Notably, the difference in species richness among age classes was merely significant for shrub and herb species. Moreover, the phylogenetic structure changed towards over-dispersion with increasing community age. (2) The age class of the community played a pivotal role in determining taxonomic β diversity in the tree layer, while climate and soil factors significantly influenced β diversity in the shrub and herb layers of the communities. (3) Environmental filtering emerged as the predominant force shaping community assembly at the intra-site scale, whereas spatial distance was the primary determinant at the inter-site scale. Meanwhile, dispersal limitation versus biological interaction seemed to dominate the community dynamics of the C. orthacantha communities in the early versus middle and old ages, respectively. Our results highlight the variability in community assembly processes across different spatial and temporal scales, providing insights into the priority of the conservation and restoration of severely degraded zonal SEBFs. Expanding research to broader scales and other SEBF types, as well as considering the impacts of climate change and human activities, would provide further insights into understanding the mechanisms of community assembly and effective conservation strategies. Full article

Carbon neutrality is an important goal for addressing global warming. It can be achieved by increasing carbon storage and reducing carbon emissions. Vegetation plays a key role in storing carbon, but it is often lost or damaged, especially in areas affected by desertification. Therefore, restoring vegetation in these areas is crucial. Using advanced techniques to improve ecosystem structure can support ecological processes, and enhance soil and environmental conditions, encourage vegetation growth, and boost carbon storage effectively. This study focuses on optimizing Ecological Spatial Networks (ESNs) for revitalization and regional development, employing advanced techniques such as the MCR model for corridor construction, spatial analysis, and Gephi for mapping topological attributes. Various ecological and topological metrics were used to evaluate network performance, while the EFCT model was applied to optimize the ESN and maximize carbon sinks. In the Thal Desert, ecological source patches (ESPs) were divided into four modularity levels (15.6% to 49.54%) and five communities. The northeastern and southwestern regions showed higher ecological functionality but lower connectivity, while the central region exhibited the reverse. To enhance the ESN structure, 27 patches and 51 corridors were added to 76 existing patches, including 56 forest and 20 water/wetland patches, using the EFCT model. The optimized ESN resulted in a 14.97% improvement in carbon sink capacity compared to the unoptimized structure, primarily due to better functioning of forest and wetland areas. Enhanced connectivity between components contributed to a more resilient and stable ESN, supporting both ecological sustainability and carbon sequestration. Full article

Among the technologies for carbon neutral, CO${}_2$ geological sequestration is one of the most promising. The mechanisms of CO${}_2$ behavior within pore space are complex and influenced by multiple factors, with the geometric structure of porous formations being particularly critical to the technology’s efficiency. Among several important and challenging problems in geological sequestration, this work addresses the issue of selecting lithologies based on their geometrical structure. This study proposes a mathematical approach to characterize the geometric structure of porous rock and fluid flow using a random walk (RW) method. Our approach simulates the time evolution of particle flow through highly disordered and heterogeneous digital rock models under a pressure gradient imposed between inlet and outlet surfaces. Through RW simulations, a probabilistic model for mineralization via a clogging (pore-filling) model is introduced, to examine the accumulation of particles within porous structures over time: single-phase clogging and multiple-phase clogging. In single-phase clogging, the porosity decrease can be described as a monotonically non-increasing function of the deposition probability. However, this is no longer true in the multiple-phase strategy because large deposition probability blocks the capillaries near the inlet surface, preventing the fluid from easily invading easily the outlet. In this study, numerical studies conducted on four types of natural rocks—Bentheimer, Doddington, Estaillades, and Ketton—revealed that Ketton exhibits the highest permeability. Our results suggest that Bentheimer, Doddington, and Ketton formations are suitable candidates for CO${}_2$ sequestration, while Estaillades is less favorable from a geometric standpoint. The methods presented in this work contribute to effectively identifying natural rocks with geometric structures advantageous for CO${}_2$ storage. Full article

The area of Cunninghamia lanceolata forests in China is expansive, the soil PhytOC(phytolith-occluded organic carbon) stock of Cunninghamia lanceolata forests is a vital carbon reservoir on the global scale. Soil from the Cunninghamia lanceolata forests was collected, and the soil physicochemical indexes and phytoliths and PhytOC content were measured to explore the accumulation characteristics of PhytOC in the 0–10, 10−20, and 20−30 cm soil layers at different stand ages. The results are as follows: (1) soil phytolith content (11.98–32.60 g·kg⁻¹), PhytOC content (0.48−1.10 g·kg⁻¹), PhytOC/TSOC (1.90%−6.93%), soil PhytOC stock (0.446−1.491 t·hm⁻²), and mature forest > middle−aged forest > Huitou−sha forest > young forest. The soil PhytOC accumulation was significantly affected by stand age. Huitou−sha is not an advantageous afforestation way of Cunninghamia lanceolata. (2) the soil physicochemical properties and stand conditions had significant effects on soil PhytOC accumulation. High−silicon, carbon-rich, acidic soil environment and appropriate thinning are conducive to phytolith formation and PhytOC sequestration. (3) the accumulation potential of soil PhytOC in the Cunninghamia lanceolata forest is relatively large, and its importance as a forest carbon sink cannot be ignored. Soil PhytOC stock in Cunninghamia lanceolata forests of different stand ages will lay a foundation for accurate estimation of forest carbon sink. Full article

Soil organic carbon (SOC) is a crucial component for investigating carbon cycling and global climate change. Accurate data exhibiting the temporal and spatial distributions of SOC are very important for determining the soil carbon sequestration potential and formulating climate strategies. An important scheme of mapping SOC is to establish a link between environmental factors and SOC via different methods. The Shiyang River Basin is the third largest inland river basin in the Hexi Corridor, which has closed geographical conditions and a relatively independent carbon cycle system, making it an ideal area for carbon cycle research in arid areas. In this study, 65 SOC samples were collected and 21 environmental factors were assessed from 2011 to 2021 in the Shiyang River Basin. The linear regression (LR) method and two machine learning methods, i.e., support vector machine regression (SVR) and random forest (RF), are applied to estimate the spatial distribution of SOC. RF is slightly better than SVR because of its advantages in the comparison of classification. When latitude, slope, and the normalized vegetation index (NDVI) are used as predictor variables, the best SOC performance is shown. Compared with the Harmonized World Soil Database (HWSD), the optimal scheme improved the accuracy of the SOC significantly. Finally, the spatial distribution of SOC tended to increase, with a total increase of 135.94 g/kg across the whole basin. The northwestern part of the middle basin decreased by 2.82% because of industrial activities. The SOC in Minqin County increased by approximately 62.77% from 2011 to 2021. Thus, the variability of the spatial SOC increased. This study provides a theoretical basis for the spatial and temporal distributions of SOC in inland river basins. In addition, this study can also provide effective and scientific suggestions for carbon projects, offer a key scientific basis for understanding the carbon cycle, and support global climate change adaptation and mitigation strategies. Full article

Natural mixed forests’ carbon sequestration capacity is crucial for mitigating climate change and maintaining ecological balance. However, most of the current studies only consider the role of forest age, ignoring the influence of carbon growth grade and stand structural diversity, which leads to an increase in uncertainty in large-scale forest carbon sink assessment. The aim of this study was to quantify the effects of carbon growth grade and stand structure diversity on the carbon sink of natural mixed forests and to establish a more accurate stand carbon growth model. Based on sample data from the National Forest Inventory (NFI) of China, the stand carbon growth model was established based on Gompertz and Logistic theoretical growth models, and the forest carbon sink at the regional scale was predicted. It was found that the stand carbon growth model considering only the stand age as a single variable often had poor results, with R² less than 0.36, while R² values of the optimal model introducing carbon growth grade and stand structural diversity were 0.87 and 0.48, respectively, which significantly improved the prediction accuracy of the model, and both had significant effects on stand carbon stocks. By predicting the future forest carbon sink, it was found that the forest carbon sink of the natural coniferous–broadleaved mixed forests in Jilin Province would reach 791 (781–801) t c/a and 843 (833–852) t c/a in 2030 and 2060, respectively, which were 17% lower and 51% higher than that of the forest carbon sink estimated by considering only the age. Moreover, the model considering structural diversity predicted a more positive carbon sink trend, indicating that forest carbon stocks could be more effectively maintained and carbon sinks increased by increasing the complexity of stand diameter at breast height structure, which has important guiding significance for future forest carbon sink management. This study provides scientific support for achieving the goal of “carbon neutrality” proposed by China. Full article