Journal of Environmental Management最新文献

Seagrasses such as Zostera marina are ecologically vital, providing essential habitats and ecosystem services that are increasingly threatened by global decline. A comprehensive understanding of seedling development, particularly the functional role of hypocotyls, is critical for effective seagrass restoration. This study investigates the ecological functions of hypocotyls during early Zostera marina seedling growth, with a focus on nutrient provisioning and the impact of hypocotyl removal on seedling performance. Hypocotyls play a critical role in early-stage nutrient allocation and water uptake-processes that are fundamental to successful seedling establishment. The developmental phase-defined as the interval from cotyledon emergence (1 cm in length) to emergence of the first true leaf (1 cm in length), followed by a fixed 20-day post-emergence growth period-is characterized by intense, developmentally regulated nutrient mobilization. During this phase, the daily degradation rates of total sugar and starch in the hypocotyl are 2.41% and 0.08%, respectively. A marked decrease in protein, total sugar, and starch content within the hypocotyls is observed as seedlings progress through early development, indicating active utilization of these reserves to support growth. Early removal of the hypocotyl leads to significantly reduced survival and impaired physiological condition, whereas removal after 27 or 37 days of growth has negligible effects. In these later treatments, seedling survival exceeded 50%, with no statistically significant difference from control groups, and survival trends approached stabilization. These findings underscore the essential contribution of the hypocotyl to early seedling viability and provide empirical evidence for optimizing the timing of seedling handling and transplantation in restoration initiatives, thereby enhancing the effectiveness of conservation strategies for these critical marine ecosystems.

The carboxylate platform offers a sustainable bioconversion strategy for biorefineries, utilizing anaerobic mixed cultures to produce carboxylate mixtures, including medium-chain fatty acids (MCFAs), as valuable intermediates. The effects of carbon sources (glucose, glycerol, casein) and exogenous supplied electron donors (ethanol, methanol, propanol, pyruvate) on MCFA production via chain elongation were investigated to elucidate the role of external electron donors and assess the feasibility of self-sufficient MCFA production in their absence. For this purpose, all experimental sets included corresponding control conditions without external electron donor addition. Batch experiments were conducted without active pH control, allowing pH to evolve dynamically in response to substrate type and metabolic activity. Results showed that the carbon source significantly affected carboxylic acid production and composition. Glucose primarily yielded propionate, independent of the electron donor. Casein resulted in the lowest carboxylic acid and gas production but uniquely produced the highest MCFA. Acidic pH conditions (5.0-5.5), which developed primarily in glucose- and glycerol-fed systems, favoured short-chain fatty acid production, whereas near-neutral pH conditions (6.0-6.7), observed in casein-fed systems, enhanced MCFA formation. Electron donors significantly influenced the degradation rate of glycerol. Methane production was observed in glucose and glycerol sets but was absent in casein sets. Microbial community analysis revealed methanogen dominance across most sets, irrespective of substrate. These findings highlight the complex interactions between pH, electron donor/acceptor availability, and microbial community dynamics in anaerobic digestion. Future multi-omics and flux analyses are needed to elucidate the metabolic pathways governing chain elongation and anaerobic digestion.

A high organic loading during anaerobic digestion (AD) of corn straw frequently triggers rapid volatile fatty acid (VFA) accumulation, pH decline, and process failure, partially due to inefficient syntrophic interactions and interspecies electron transfer. In this study, anthraquinone-2-sulfonate was grafted onto biochar to obtain quinone-modified biochar (QMBC), which was used to stabilize high-load AD of corn straw in a semi-continuous reactor. The results showed that during a high organic loading rate (OLR) of 2.36 g VS/L∙d, QMBC alleviated acid inhibition, reduced the total VFA concentration by 77.38 %, increased biogas production by 177.87 %, and maintained a methane concentration above 60 %. QMBC enriched electroactive bacteria, including Lentimicrobium (10.78 %) and Flexilinea (6.33 %), which were significantly and positively correlated with changes in the abundance of Methanobacterium and Methanosarcina. Functional predictions indicated significant enhancement of ccmEFGH and enzymes related to coenzyme F₄₂₀ synthesis. Overall, quinone-functionalized biochar represents a practical additive to improve the stability and biogas production of high-loading AD.

The application of nanoparticles (NPs) in microalgae-based systems has emerged as a flexible strategy to enhance wastewater treatment and biomass valorization, while promoting circular bioeconomy pathways. This critical review analyzes over one hundred studies published between 2015 and 2025, which evaluated the use of metallic, metal oxide, and carbon-based NPs in microalgal cultivation, harvesting, green synthesis, and toxicity assessment. Based on these studies, optimized NP concentrations can enhance photosynthetic efficiency, improve nutrient and organic pollutant removal, and modulate biomass composition toward biofuels and value added bioproducts, including pigments, biopolymers, and biofertilizers. Magnetically assisted harvesting and microalgae-mediated NP synthesis can be combined synergistically to reduce energy demands and separation costs. However, key challenges remain, notably the definition of safe and effective dosage ranges, the lack of standardized ecotoxicological protocols, and the scarcity of pilot- and industrial-scale validations. Additional obstacles include limited performance benchmarking against conventional technologies and uncertainties related to life cycle assessments and cost analyses. By integrating nanotechnology, microalgal biotechnology, and sustainability assessment, this review outlines strategic pathways to translate laboratory advances into scalable, economically viable, and environmentally safe applications, reinforcing the role of microalgae-NP systems in environmental sanitation and the bioeconomy.

Saltwater intrusion poses serious threats to water ecosystems, agricultural production, industrial activities, and especially drinking water safety in estuarine regions. Addressing saltwater intrusion through water resources regulation requires accurate predictions of its duration of impact, namely the hours of chloride exceedance. However, existing saltwater intrusion predictions suffer from short lead times and low accuracy. This study develops a sequence learning framework for the long-term prediction of monthly hours exceeding the chloride threshold (250 mg/L). A sequence-to-sequence prediction paradigm is developed based on the periodic characteristics of saltwater intrusion. Statistical features, particularly extreme-value features, are incorporated to enhance the representation of high-value saltwater intrusion processes. This framework enables reliable prediction of monthly hours exceeding the chloride threshold, with a lead time of 12 months. The results show that extreme-value-based statistical features have correlations with exceedance hours that are comparable to, or even higher than, those based on mean values. Under a 12-month lead time, the sequence learning framework achieved Nash-Sutcliffe Efficiency (NSE) values of 0.817 and 0.798 at the two representative stations. Compared with Random Forest, Gated Recurrent Unit, and Long Short-Term Memory models, the framework improved NSE by more than 0.5 for both the full year and the dry season evaluation. When incorporating the spatial correlation between stations, the joint prediction approach increased the annual NSE by 0.128 relative to single-station prediction. Overall, the framework effectively captured the periodic characteristics of saltwater intrusion and high-value during the dry season, demonstrating strong long-term predictive capability.

A thermotolerant, odor-suppressing microbial agent was inoculated into food-waste (FW) composting to systematically evaluate its influence on odorants, volatile organic compounds (VOCs), microbial community structure, extracellular enzyme activities, and the transcriptional profile of nitrogen- and sulfur-cycle genes. Compared with the uninoculated control, cumulative emissions of NH₃, H₂S, ethanol, and acetaldehyde declined by 73.45%, 65.30%, 40.22%, and 37.20%, respectively, in the bio-augmented reactor. NH₃ High-throughput 16S rRNA sequencing revealed that the inoculation enhanced the microbial richness and diversity, while increasing the abundance of thermophilic strains that promote compost maturation and reduce nitrogen loss. Concomitantly, the relative abundances of acid-producing and skatole-generating populations were suppressed. Quantitative PCR showed that the expression of narG, norB, nif, nrfA, nirB, aprA, and sat genes was down-regulated. This consequently reduced the production of NH₄⁺-N and inhibited the sulfate reduction process, thereby coordinating nitrogen and sulfur metabolic transformations and significantly lowering NH₃ and H₂S emissions. Overall, this study demonstrates the feasibility of microbial inoculation for mitigating odor emissions, retaining nutrients, and accelerating compost maturation, while providing mechanistic insights into how microbial formulations regulate enzyme activities and the expression of functional genes during composting.

Effective management of ecological risks in canal watersheds, crucial for sustaining ecosystem services and maintaining ecological integrity, is facing significant challenges due to complex human-environment interactions. Traditional zoning approaches rely primarily on static indicators, potentially overlooking the spatial dynamics of ecosystem services (ESs). To address this, this study integrates ecosystem service flows (ESFs), which are dynamic, spatially explicit representations of ES delivery, into ecological risk zoning within the Pinglu Canal Watershed in China. First, we quantified and mapped the spatial patterns of four key ESFs: water yield (WY), habitat quality (HQ), crop production (CP), and tourism & recreation (TR). Next, we evaluated ecological risks by building causal networks linking risk sources, exposure processes, and ES responses. Using these integrated risk-flow results, we delineated management zones through k-means clustering. The main conclusions are as follows: (1) Six ecological management zones were identified (33.93%, 7.48%, 2.62%, 32.63%, 22.28%, and 1.06% of the watershed), each characterized by distinct ecological functions and dominant risk attributes. Specifically, Cluster 6 requires integrated cross-sectoral management due to overlapping agricultural, biodiversity, and tourism pressures, while Cluster 3 highlights the need for land-use control and ecological corridor restoration. Other zones serve regulatory (Clusters 1 and 4), buffering (Cluster 5), or monitoring (Cluster 2) functions, forming a gradient governance framework. (2) While previous studies often assessed ecological risks based on static ES, this study integrates dynamic ESFs to account for spatial continuity and flow direction. This enables the identification of not only areas where ESs are under pressure but also the manners in which ecological risks spatially disrupt ES flow paths. (3) This integration provides a basis for targeted ecological risk coordinated management, applicable not only to the Pinglu Canal but also to similar watersheds globally.

The recovery and utilization of valuable resources in excess sludge from wastewater treatment plants are of considerable research interest. In this study, alkaline-extracted polymer substances (AEPS) from excess sludge were modified with phytic acid (PA) and tested as a potential flame retardant. Thermogravimetry analysis showed that treating cotton fabric with the resulting bio-based flame retardant increased the residual carbon rate to 30.3%, and scanning electron microscopy observations showed that a carbon layer was formed on the treated fabric that greatly improved the thermal stability. The treated fabric also showed an increase in the limiting oxygen index, and the total heat release decreased by 33.8%. While PA is already an excellent flame retardant, the incorporation of AEPS alleviated the damage to the mechanical properties of the cotton fabric caused by the strong acidity of PA, which increased the maximum tensile strength of the fabric. These results demonstrate the strong potential of the developed bio-based flame retardant and the synergistic effects of AEPS and PA.

Climatic and anthropogenic pressures have caused significant changes in ocean ecosystems, but the long-term impacts on phytoplankton and underlying mechanisms in the continental shelf areas remain inadequately quantified. In this study, we reconstructed century-long records of phytoplankton productivity (PP) and community structure on the northern South China Sea (SCS) shelf using a combination of sedimentary lipid biomarkers (sterols and long-chain alkyl diols) and bulk geochemical proxies. The results revealed that diatoms and dinoflagellates predominated, with PP showing a consistent increasing trend over the past century, particularly accelerating after the 1980s. However, community structure exhibited divergent spatial trajectories. The relative abundance of dinoflagellates increased in the nearshore area, whereas diatoms increased offshore in recent decades. Statistical analyses identified the 1980s as a critical transition period, which was attributed to changes in sea surface temperature (SST) and nutrient levels. The Generalized Additive Model (GAM) results further demonstrated SST and nitrogen exerted cumulative and synergistic effects on promoting PP in the anthropogenically impacted nearshore region. This synergy, characterized by ocean warming coupled with elevated nitrogen loading and N/P ratios, favored the proliferation of dinoflagellates. The findings underscore that under ongoing climate change, proactive measures to control anthropogenic nitrogen inputs are crucial to mitigate the expanding frequency and geographical coverage of dinoflagellate blooms in coastal shelf ecosystems.

The overuse of ceftriaxone has resulted in its widespread occurrence in aquatic environments, posing ecological and health risks. An anaerobic membrane bioreactor (AnMBR) was operated for 128 days to systematically investigate the anaerobic microbial transformation of CTX. The AnMBR exhibited stable and efficient performance, maintaining chemical oxygen demand removal above 90% and achieving an average CTX removal efficiency of 65.0 ± 15.2%. Several potential degradation pathways are proposed, involving β-lactam ring hydrolysis, C-S bond cleavage, and decarboxylation reactions. Toxicity assessments using ADMETlab 3.0 platform reveal that although most TPs showed reduced ecotoxicity and dermal toxicity compared to the parent compound, several intermediates exhibited elevated risks of nephrotoxicity and genotoxicity. Metagenomic analysis indicates that long-term CTX exposure reshaped the microbial community, enriching methanogens such as Methanothrix soehngenii and Methanosarcina mazei, though these taxa might not directly participate in CTX degradation. Several archaeal and bacterial MAGs carrying functional genes, including lactam hydrolase, thioesterase, and decarboxylase, were identified, suggesting a collaborative and functionally diverse microbial network involved in CTX transformation. This study offers mechanistic insights and technical foundations for advancing anaerobic biotechnologies in the treatment of antibiotic-contaminated wastewater, while highlighting the need for ongoing monitoring of potential long-term risks associated with TPs.