Journal of Environmental Management最新文献

The global shift towards renewable energy sources highlights the urgent need for sustainable hydrogen production, with photo-fermentative hydrogen evolution (PFHP) emerging as a promising solution. This review addresses the challenges and opportunities in optimizing PFHP, specifically the role of photosynthetic bacteria (PBS) in utilizing sunlight for hydrogen production. We focus on the key factors influencing PFHP, including light intensity, reactor design, substrate selection, carbon-to-nitrogen ratio, metal ions, temperature, pH, charge transfer and genetic engineering. Additionally, we explore recent advances in techniques such as immobilization, nanoparticles, biochar, and co-culturing to enhance hydrogen production efficiency. By synthesizing the latest research, this review provides new insights into improving PFHP processes, offering strategies for more efficient biohydrogen production. This work contributes to the development of sustainable hydrogen production technologies, advancing the potential for biohydrogen as a clean energy source.

The toxicity of nitrite is an issue that cannot be overlooked in nitrogen pollution within aquaculture. A highly efficient bacterium capable of simultaneous nitrification and denitrification was screened from natto, and its 16S rRNA gene sequence was compared to existing records, confirming its identification as Bacillus subtilis sp. N4. The optimal conditions for nitrite degradation by B. subtilis sp. N4 were identified using response surface methodology as 167 rpm, pH 6.4, 1 g/8 mL feed, 0.6 OD₆₀₀, and 30 °C, with a predicted 99 % nitrite removal efficiency. The B. subtilis sp. N4 demonstrated a maximum nitrite concentration tolerance of 60 mg/L, with μ_max and Ks values calculated using a Monod model analysis of 1.67 mg/L/h and 0.29 mg/L, respectively. Immobilized B. subtilis sp. N4 could be reused for ten cycles while maintaining a nitrite degradation efficiency of >99 %, and retained a high nitrite-degrading ability after being refrigerated at 4 °C for three months. Immobilized B. subtilis sp. N4 effectively reduced ammonia nitrogen, nitrite, and nitrate concentrations in Nile tilapia aquaculture, maintaining them at consistently low levels. Therefore, free or immobilized B. subtilis sp. N4, with both nitrification and denitrification capabilities, has considerable potential for application in the aquaculture industry in the future.

Arthropods play a critical role in the functioning of grassland ecosystems, and are largely affected by herbivore grazing. However, the mechanisms of grazing affecting arthropod community, especially through modulating plant traits and soil properties, are still unclear. We investigated the variation in arthropod community variables including family richness, activity-density, biomass, and body size in typical steppe grasslands subject to grazing at four intensity levels (nil, light, moderate and heavy) in central Inner Mongolia (China), and analyzed the relationships of these variations with grazing-induced changes in plant traits, plant community attributes and soil properties. We found that (i) at the community level, arthropod family richness was lower in moderately-grazed than in both lightly- and heavily-grazed grasslands, but no significant difference was detected between grazing and no-grazing grasslands. The high arthropod community activity-density was found in plant communities with high plant leaf nitrogen content and low water content. (ii) With increasing grazing intensity, the biomass of arthropod community decreased, while the proportion of small-sized arthropods increased, and the family composition, especially the families of Coleoptera changed. (iii) The response of arthropods to grazing intensity differed among arthropod orders. The family richness of Coleoptera, Diptera and Homoptera increased with the increase of plant leaf water content and C:N ratio or the decrease of leaf nitrogen content; Orthoptera activity-density declined with increasing grazing intensity, but showed no significant correlation with plant leaf traits, community attributes, or soil water content; Hymenoptera activity-density declined with the increase of plant height, biomass and cover, and the decrease of plant individual density and family richness; a greater Lepidoptera activity-density was found in the grassland with high vegetation cover and moist soil; and Diptera exhibited larger biomass and body size in grasslands with increased plant nitrogen content. (iv) Depending on grazing conditions, some arthropod families may alter their feeding preferences and select more stable environmental conditions for survival, potentially weakening the inherent relationship between arthropods and plants. Our study implies it is necessary to incorporate the dynamics of ground arthropods into the grassland management for conservation and sustainable use of grassland ecosystems.

The growth of population and changes in dietary structure have led to a continuous increase in demand for livestock and poultry products, resulting in the increase of the gaseous reactive nitrogen (GNr) emissions from livestock and poultry breeding systems and posing a threat to the human and ecosystem health. The characteristics from GNr emissions of six livestock and poultry breeding systems at the provincial level of China in 2020 were evaluated with the framework of life cycle analysis. Additionally, this study explored the impact of silage maize replacing traditional maize as feed on reducing GNr emissions. The GNr emissions from producing 1 ton of beef were the highest, approximately 9 times higher than those from producing 1 ton of milk. The GNr emissions for production of 1 ton of pork and egg were the biggest in Zhejiang. And the biggest emissions for 1 ton of beef, mutton, chicken and milk production were in Xizang, Shaanxi, Guangdong, and Guangxi, respectively. The total GNr emissions from pork production were highest. Compared with other stages, the stages of manure management and feed production contributed the majority of GNr emissions. Assuming that all the feed crops required for the production of livestock and poultry products in 2020 were locally grown, the total GNr emissions from the production of livestock and poultry products of China in 2020 were 6143.94 kt N, indicated that local emissions in China only accounted for 57.90%. Moreover, when the substitution rate of silage maize reached 100%, the GNr emissions from livestock and poultry breeding systems would be reduced by 10.05% (324.98 kt N). This study provided a detailed and spatial overview of the GNr emissions in livestock and poultry production in China, which could support reducing GNr emissions in livestock and poultry breeding systems for decision-makers and air pollution control.

In-channel persistent surface water provides critical refuge habitat for aquatic organisms in intermittently flowing rivers. Quantifying the flows that maintain connectivity among persistent waterholes is important for managing river flows to maintain refuges, improve their quality and facilitate connectivity and nutrient and energy transport. This study aimed to quantify spatial and temporal waterhole persistence and connectivity in a 664 km reach of the Darling River in Australia's Murray-Darling Basin. A 35-year satellite imagery record and graph theory were combined to produce a time series of spatial graphs. Persistent in-channel waterholes represented nodes on the graph, with vertices reflecting connectivity during flow events. Models were developed to quantify temporal variation in connectivity in relation to environmental predictors at a reach scale and at specific waterholes. Connectivity was highly spatially variable and clearly impacted by flow interception at in-channel weirs. Several highly connected waterholes were identified as both hub and stepping stone habitats in the connectivity analysis, indicating that they may serve important ecological functions for both local and large-scale fish dispersal. Flow was the most influential predictor of reach-scale connectivity, followed by local rainfall. An analysis of specific waterholes found that following a reconnecting flow event, flow above the 75th percentile was required to maintain full connectivity of the most disconnected/isolated waterhole. This study demonstrated that connectivity can be predicted using variables including flow, rainfall, and antecedent climate conditions, thereby highlighting the usefulness of this technique for predicting connectivity under a range of flow scenarios.

The primary goal of the current work was to construct pH-sensitive nano and microcomposite hydrogel beads based on alginate (AL), carboxymethyl cellulose (CMC), biochar (BC), and two Moroccan clays: Ghassoul (swelling SW) and red (not swelling NSW) nano and microhybrid. The adsorbents, SW + AL, SW + AL + BC, SW + AL + CMC, NSW + AL, NSW + AL + BC, NSW + AL + CMC, AL, and AL + CMC were prepared for the adsorption of the antibiotic sulfadiazine (SDZ). The test samples were characterized using a variety of techniques, including X-Ray Diffraction (XRD), IR spectroscopy (FT-IR), and scanning electron microscopy (SEM), with the molecular structures of the studied additives geometrically optimized using the DFT/B3LYP method and the function 6-311G(d). Molecular electrostatic potential (MEP) and Mulliken charge analysis were utilized to estimate the adsorption sites of the additives under study, with conformational analysis using Monte Carlo (MC) simulations and Hirshfeld surface (HS) analysis to gain a better understanding of the SDZ's adsorption process on the clay and polymer surfaces through its sulfonyl, amino, and carboxylate groups. The study found that SW + AL + CMC beads had a maximum adsorption capability of 800 μmol/kg for SDZ. Furthermore, this composite demonstrated more than 100% adsorption and 0% subsequent desorption. The findings of this study point to the possibility of using SW + AL + CMC nanocomposite for SDZ removal, which would be useful for the environment and public health.

The wind-blown sand protection system in the Shapotou section of the Baotou-Lanzhou Railway is a representative artificial ecosystem in a desert region. Over the past 70 years, this system has transformed mobile dunes into fixed dunes through vegetation succession, relying solely on natural rainfall without additional irrigation. However, ecosystem sustainability has been endangered by the emergence of numerous blowouts. Therefore, understanding the status and developmental trends of these blowouts is crucial for maintaining the system and ensuring railway safety. In this study, we quantitatively analyzed the number, spatial pattern, and evolution process of blowouts using a landscape pattern index and Spatial-Temporal Analysis of Moving Polygons (STAMP) model with remote sensing images from 2009 to 2022. Currently, blowout areas account for 1.57% of the total area with a clustered distribution. The number of blowouts increased significantly from 308 to 463 between 2009 and 2022 and increased with increasing distance from the railway line. Various evolutionary events have occurred among the blowouts, with peak frequencies in the generation and disappearance events observed by 2022. The average growth rate of blowouts was 7.32% in areas with less than 40 years of sand fixation but less than 1% in areas with more than 40 years, and mid-sized blowouts predominated the overall protection system. There was little difference between the blowout wind-erosion area and the fixed area in the natural environment. However, human activities can accelerate the evolution of blowouts, leading to more frequent contraction and expansion events and significantly increasing the area of wind erosion.

Mangrove forests play an important role in climate change mitigation and adaptation, globally recognized as natural climate solution. The protection and restoration of mangrove ecosystems are especially important to Small Island Developing States, like Seychelles, due to their vulnerability to the impacts of climate change, such as sea level rise and tropical cyclones. Therefore, it is crucial for countries like Seychelles to develop baseline information on the status of their mangrove forests to guide conservation and management actions. In this study, we conducted a field campaign to collect local data on plant (i.e., aboveground and belowground) and soil carbon from representative mangrove forests in the inner and outer islands of Seychelles. We used this data to develop, for the first time, a blue carbon assessment for Seychelles' mangrove ecosystems. Seychelles holds 2195 ha of mangrove forests, with ∼80% of them found on the outer island of Aldabra Atoll. Seychelles mangrove ecosystems store 688,091 ± 18,353 tonnes of organic carbon (or 2.5 million tonnes CO₂e) and an average of 477.0 ± 16.2 tonnes of carbon per hectare, with 70% of their total carbon stocks stored in their soils. Aldabra Atoll holds the highest total carbon stocks, accounting for 67% of Seychelles' mangrove stocks, despite having a relatively shallow soil organic layer (∼40 cm) due to the dominance of limestone and 'coral champignon' below 40 cm depth. Seychelles currently protects ∼85% of its mangrove extent including the Aldabra Atoll, a UNESCO World Heritage and Ramsar site, and Port Launay, a Ramsar site. Overall, field data from this study demonstrates the important climate mitigation potential of Seychelles' mangrove forests and the important role they play in supporting Seychelles in achieving its Nationally Determined Contributions (NDCs) commitments.

Corruption involves abuse of power and increases economic inequality, which may hinder progress toward achieving the United Nations' Sustainable Development Goal 16.B. While some studies have examined the economic and environmental implications of corruption, the dynamic relationship between the environmental efficiency and different levels of corruption in different countries, while accounting for their respective geographical regions, has still not been fully explored. To address this gap, this study proposes a dynamic alternative which is meta-frontier slacks-based measure approach to investigate variations in environmental efficiency across different corruption levels while accounting for geographic regions. Empirical results reveal that the corruption perception index is associated with environmental efficiency, and that geographical region and government transparency are both determinants of environmental efficiency.

The purpose of this study is to evaluate the readiness of European inland transport companies for the European Green Deal by analyzing the causal relationships between key factors essential for EGD implementation. The research identifies six critical factors: Investment in Green Technologies, Policy Alignment and Compliance, Stakeholder Collaboration, Resource Management, Employee Training and Engagement, and Emission Reduction Initiatives. This research offers the first integrated evaluation of EGD readiness utilizing a combination of fuzzy-DEMATEL, multiple regression analysis, and Structural Equation Modeling aimed at uncovering systemic interactions among the factors in the system. The study revealed Resource Management and Employee Training as significant drivers in enhancing the readiness, highlighting the role of human capital and resource optimization in environmental sustainability. Expert panel, consisting of 19 industry representatives selected through purposive sampling, provided insights on the effective relationships which offer practical strategies for managers to prioritize resource management and employee engagement to achieve Green Deal compliance and guiding more strategic and efficient allocation of resources to enhance alignment with European Green Deal stipulations.