Environmental Science and Ecotechnology最新文献

The concentration of atmospheric CO₂ has exceeded 400 ppm, surpassing its natural variability and raising concerns about uncontrollable shifts in the carbon cycle, leading to significant climate and environmental impacts. A promising method to balance carbon levels and mitigate atmospheric CO₂ rise is through photocatalytic CO₂ reduction. Titanium dioxide (TiO₂), renowned for its affordability, stability, availability, and eco-friendliness, stands out as an exemplary catalyst in photocatalytic CO₂ reduction. Various strategies have been proposed to modify TiO₂ for photocatalytic CO₂ reduction and improve catalytic activity and product selectivity. However, few studies have systematically summarized these strategies and analyzed their advantages, disadvantages, and current progress. Here, we comprehensively review recent advancements in TiO₂ engineering, focusing on crystal engineering, interface design, and reactive site construction to enhance photocatalytic efficiency and product selectivity. We discuss how modifications in TiO₂'s optical characteristics, carrier migration, and active site design have led to varied and selective CO₂ reduction products. These enhancements are thoroughly analyzed through experimental data and theoretical calculations. Additionally, we identify current challenges and suggest future research directions, emphasizing the role of TiO₂-based materials in understanding photocatalytic CO₂ reduction mechanisms and in designing effective catalysts. This review is expected to contribute to the global pursuit of carbon neutrality by providing foundational insights into the mechanisms of photocatalytic CO₂ reduction with TiO₂-based materials and guiding the development of efficient photocatalysts.

Assessing the iron and steel industry's (ISI) impact on climate change and environmental health is vital, particularly in China, where this sector significantly influences air quality and CO₂ emissions. There is a lack of comprehensive analyses that consider the environmental and health burdens of manufacturing processes for ISI enterprises. Here, we present an integrated emission inventory that encompasses air pollutants and CO₂ emissions from 811 ISI enterprises and five key manufacturing processes in 2020. Our analysis shows that sintering is the primary source of air pollution in the ISI. It contributes 71% of SO₂, 73% of NO_x, and 54% of PM_2.5 emissions. On the other hand, 81% of total CO₂ emissions come from blast furnaces. Significantly, the contributions of ISI have resulted in an increase of 3.6 μg m⁻³ in national population-weighted PM_2.5 concentration, causing approximately 59,035 premature deaths in 2020. Emissions from Hebei, Jiangsu, Shandong, Shanxi, and Inner Mongolia provinces contributed to 48% of PM_2.5-related deaths in China. Moreover, the transportation of air pollutants across provincial borders highlights a concerning trend of environmental health inequality. Based on the research findings, it is crucial for ISI manufacturers to prioritize the removal of outdated production capacities and adopt energy-efficient and advanced techniques, along with ultra-low emission technologies. This is particularly important for those manufacturers with substantial environmental footprints. These transformative actions are essential in mitigating the environmental and health impacts in the affected regions.

Biosynthesis and biodegradation of microorganisms critically underpin the development of biotechnology, new drugs and therapies, and environmental remediation. However, most uncultured microbial species along with their metabolic capacities in extreme environments, remain obscured. Here we unravel the metabolic potential of microbial dark matters (MDMs) in four deep-inland hypersaline lakes in Xinjiang, China. Utilizing metagenomic binning, we uncovered a rich diversity of 3030 metagenome-assembled genomes (MAGs) across 82 phyla, revealing a substantial portion, 2363 MAGs, as previously unclassified at the genus level. These unknown MAGs displayed unique distribution patterns across different lakes, indicating a strong correlation with varied physicochemical conditions. Our analysis revealed an extensive array of 9635 biosynthesis gene clusters (BGCs), with a remarkable 9403 being novel, suggesting untapped biotechnological potential. Notably, some MAGs from potentially new phyla exhibited a high density of these BGCs. Beyond biosynthesis, our study also identified novel biodegradation pathways, including dehalogenation, anaerobic ammonium oxidation (Anammox), and degradation of polycyclic aromatic hydrocarbons (PAHs) and plastics, in previously unknown microbial clades. These findings significantly enrich our understanding of biosynthesis and biodegradation processes and open new avenues for biotechnological innovation, emphasizing the untapped potential of microbial diversity in hypersaline environments.

The release of emerging contaminants (ECs) into aquatic environments poses a significant risk to global water security. Advanced oxidation processes (AOPs), while effective in removing ECs, are often resource and energy-intensive. Here, we introduce a novel catalyst, CoFe quantum dots embedded in graphene nanowires (CoFeQds@GN-Nws), synthesized through anaerobic polymerization. It uniquely features electron-rich and electron-poor micro-regions on its surface, enabling a self-purification mechanism in wastewater. This is achieved by harnessing the internal energy of wastewater, particularly the bonding energy of pollutants and dissolved oxygen (DO). It demonstrates exceptional efficiency in removing ECs at ambient temperature and pressure without the need for external oxidants, achieving a removal rate of nearly 100.0%. The catalyst's structure-activity relationship reveals that CoFe quantum dots facilitate an unbalanced electron distribution, forming these micro-regions. This leads to a continuous electron-donation effect, where pollutants are effectively cleaved or oxidized. Concurrently, DO is activated into superoxide anions (O₂^•−), synergistically aiding in pollutant removal. This approach reduces resource and energy demands typically associated with AOPs, marking a sustainable advancement in wastewater treatment technologies.

Cities are increasingly vital in global carbon mitigation efforts, yet few have specifically tailored carbon neutrality pathways. Furthermore, out-of-boundary indirect greenhouse gas (GHG) emissions, aside from those related to electricity and heat imports, are often overlooked in existing pathways, despite their significance in comprehensive carbon mitigation strategies. Addressing this gap, here we introduce an integrated analysis framework focusing on both production and consumption-related GHG emissions. Applied to Wuyishan, a service-oriented city in Southern China, this framework provides a holistic view of a city's carbon neutrality pathway, from a full-scope GHG emission perspective. The findings reveal the equal importance of carbon reduction within and outside the city's boundaries, with out-of-boundary emissions accounting for 42% of Wuyishan's present total GHG emissions. This insight highlights the necessity of including these external factors in GHG accounting and mitigation strategy development. This framework serves as a practical tool for cities, particularly in developing countries, to craft effective carbon neutrality roadmaps that encompass the full spectrum of GHG emissions.

Candidatus Accumulibacter, a prominent polyphosphate-accumulating organism (PAO) in wastewater treatment, plays a crucial role in enhanced biological phosphorus removal (EBPR). The genetic underpinnings of its polyphosphate accumulation capabilities, however, remain largely unknown. Here, we conducted a comprehensive genomic analysis of Ca. Accumulibacter-PAOs and their relatives within the Rhodocyclaceae family, identifying 124 core genes acquired via horizontal gene transfer (HGT) at its least common ancestor. Metatranscriptomic analysis of an enrichment culture of Ca. Accumulibacter revealed active transcription of 44 of these genes during an EBPR cycle, notably including the polyphosphate kinase 2 (PPK2) gene instead of the commonly recognized polyphosphate kinase 1 (PPK1) gene. Intriguingly, the phosphate regulon (Pho) genes showed minimal transcriptions, pointing to a distinctive fact of Pho dysregulation, where PhoU, the phosphate signaling complex protein, was not regulating the high-affinity phosphate transport (Pst) system, resulting in continuous phosphate uptake. To prevent phosphate toxicity, Ca. Accumulibacter utilized the laterally acquired PPK2 to condense phosphate into polyphosphate, resulting in the polyphosphate-accumulating feature. This study provides novel insights into the evolutionary emergence of the polyphosphate-accumulating trait in Ca. Accumulibacter, offering potential advancements in understanding the PAO phenotype in the EBPR process.

Peracetic acid (PAA), known for its environmentally friendly properties as a oxidant and bactericide, is gaining prominence in decontamination and disinfection applications. The primary product of PAA oxidation is acetate that can serve as an electron acceptor (EA) for the biosynthesis of medium-chain fatty acids (MCFAs) via chain elongation (CE) reactions. Hence, PAA-based pretreatment is supposed to be beneficial for MCFAs production from anaerobic sludge fermentation, as it could enhance organic matter availability, suppress competing microorganisms and furnish EA by providing acetate. However, such a hypothesis has rarely been proved. Here we reveal that PAA-based pretreatment leads to significant exfoliation of extracellular polymeric substances (EPS) from sludge flocs and disruption of proteinic secondary structures, through inducing highly active free radicals and singlet oxygen. The production of MCFAs increases substantially to 11,265.6 mg COD L⁻¹, while the undesired byproducts, specifically long-chain alcohols (LCAs), decrease to 723.5 mg COD L⁻¹. Microbial activity tests further demonstrate that PAA pretreatment stimulates the CE process, attributed to the up-regulation of functional genes involved in fatty acid biosynthesis pathway. These comprehensive findings provide insights into the effectiveness and mechanisms behind enhanced MCFAs production through PAA-based technology, advancing our understanding of sustainable resource recovery from sewage sludge.

Microplastics (MPs), recognized as an emerging global environmental concern, have been extensively detected worldwide, with specific attention directed towards the Yangtze River Estuary (YRE) and East China Sea (ECS) regions. Despite their critical research significance, there remains a knowledge gap concerning the distribution of MPs in the benthic layer within this area, particularly regarding interactions governing their occurrence. Here we illuminate the distribution of MPs within the benthic layer and unravel the intricate interplay between bottom water and sediment in the YRE and ECS. We find that MPs are notably more abundant in bottom water, ranging from 8 to 175 times higher than in surface water. These MPs predominantly consist of polyester fibers, exhibit a size range between 0.5 and 5.0 mm, and display distinct coloration. Co-occurrence network analysis and Principal Coordinate Analysis confirm a robust correlation between MPs in bottom water and sediment, signifying the pivotal role of bottom water in mediating the distribution and transportation of MPs within the benthic layer. Furthermore, a positive correlation between MPs in sediment and bottom water turbidity underscores the impact of surface sediment resuspension and upwelling on MPs distribution. This study clarifies the intricate interactions within the benthic layer and highlights the crucial role of bottom water as a mediator in the vertical distribution of MPs, advancing our understanding of the “source-to-sink” transport processes governing MPs within water-sediment systems.