Journal of Environmental Management最新文献

High-concentration phosphorus in pesticide tailwater threatens ecosystem balance due to its toxicity and persistence. While abundant nanosheet structures in LDH(layered double hydroxides)-modified biomass enhance wastewater anion adsorption, optimizing LDH structures to maximize phosphate adsorption and elucidating the underlying microscopic mechanisms require further research. This study employed batch adsorption experiments combined with Response Surface Methodology (RSM) to optimize the synthesis conditions of Mg/Al-LDH modified biochar (MABC). The mechanisms underlying its efficient phosphorus adsorption were systematically investigated through XRD, XPS, FTIR, and SEM characterizations. Results show that MABC₆ optimized by RSM (Mg/Al molar ratio 4:1, biochar dosage 10 g·100 mL^-1, roasting temperature 450 °C) exhibited high crystallinity, large specific surface area, abundant surface functional groups, and maximum layer spacing, demonstrating optimal adsorption performance (54.932 mg g^-1). Chemical adsorption, multilayer adsorption, electrostatic attraction, ion exchange, inner-sphere and outer-sphere surface complexation, and ligand exchange are the main mechanisms of the MABC adsorption process. The optimized MABC₆, owing to its increased surface functional groups and expanded layer spacing, promotes multilayer adsorption and ligand exchange while strengthening ion exchange and ligand exchange. This enhances the effective binding between phosphate and adsorption sites. Additionally, soil column experiments indicated that phosphorus-enriched MABC₆ (MABC₆-P) achieved a cumulative phosphate release rate of 17.59% within 30 days, representing a 50.21% relative increase compared to the raw biochar(BC), highlighting its promising potential for slow-release fertilizer applications. In summary, this study optimized the LDHs-biochar crystalline structure via RSM to expand layer spacing, thereby enhancing adsorption capacity and extending its application in aquatic environmental remediation.

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.

How hydrological period conversions, including the water diversion period (WDP) and flood discharge period (FDP), influence microbial communities, their assembly mechanisms, and community stability remains poorly understood in large-scale water diversion systems. Herein, we conducted a comprehensive field survey of micro-eukaryotic communities across the 1045 km canal system and four impoundment lakes of the eastern route of the South-to-North Water Diversion Project (ER-SNWDP) during a complete diversion cycle. Our results showed that hydrological period conversions caused homogenization of the micro-eukaryotic communities, which was primarily driven by abundant taxa and significantly more pronounced during WDP than during FDP (p < 0.001). The underlying assembly processes behind the homogenization in WDP were ecological drift and dispersal, followed by homogeneous selection. However, the stochastic processes of ecological drift and dispersal dominated the assembly of the homogenized micro-eukaryotic community in FDP, possibly due to relatively stronger hydrological disturbances overshading the environmental filtering effects. Micro-eukaryotic biodiversity promoted network complexity and enhanced community stability, thereby counteracting the negative impacts of biotic homogenization. Network-associated communities exhibited pronounced compositional turnover across hydrological periods, with abundant taxa showing greater robustness than rare taxa. While abundant and rare taxa played comparable roles in stabilizing microbial networks during WDP, their relative contributions diverged markedly from WDP to FDP, indicating that increasing environmental pressure amplified the "Matthew effect" in the microbial world. Collectively, this study offers insights into the ecological consequences of hydrological period conversions in the ER-SNWDP, highlighting the importance of integrating microbial biodiversity conservation into multi-purpose water management.

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.

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.

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.

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.