Abstract Landfill leachate is a persistent environmental stressor, yet this study shows that seasonal hydrology and stormwater runoff, rather than leachate intrusion, primarily govern surface water chemistry and microbial community organization near engineered landfill systems in Malaysia. Multivariate analyses revealed seasonal variability in physicochemical parameters, while conservative tracer ratios and clay liner performance confirmed the absence of leachate ingress, underscoring containment effectiveness. Hydrological variability exerted primary control over microbial assemblages. 16S rRNA sequencing and PICRUSt2 inference indicated reduced α-diversity under dry-season low-flow conditions, with β-diversity analyses showing no significant seasonal separation (p > 0.05). Ternary compositional analysis revealed enhanced richness and compositional balance during the rainy season, attributable to increased hydrological mixing and dispersal. Dry-season assemblages exhibited dominance structures and enrichment of stress-adapted lineages. Phylum-level restructuring reflected seasonal gradients: Pseudomonadota and Bacteroidota prevailed during the rainy season, while Actinobacteriota and Bacillota dominated under ionic stress and reduced dilution. The persistence of core genera across seasons highlights microbial resilience and functional adaptability within dynamic biogeochemical interfaces. These results indicate that stormwater runoff, not landfill-derived leachate, drives observed microbial and hydrochemical dynamics. Findings are broadly applicable to regions with seasonal precipitation and expanding impermeable surfaces, informing global landfill performance assessments, monitoring strategies, and risk communication.
Abstract Drinking water odor pollution and pipeline corrosion seriously threaten drinking water safety. Odor-producing algae can penetrate conventional water treatment processes and enter drinking water distribution networks, causing prominent water quality risks. Taking Microcystis aeruginosa as the target alga, this study investigated the effects and underlying mechanisms of pipeline corrosion products (CPs) on the formation of algal odorants under chlorination conditions. The results show that the coexisting system of CPs and chlorine significantly promotes the release of β-cyclocitral from M. aeruginosa while reducing the rupture rate of algal cells. The underlying reason is that CPs consume chlorine in the system, lowering the actual chlorine exposure dose and alleviating oxidative damage to algal cells. Meanwhile, the coexistence of CPs and chlorine may induce oxidative stress in algal cells, potentially further affecting the synthesis and release of β-cyclocitral by M. aeruginosa. Transcriptomic analysis reveals that, in the coexistence system of chlorine and CPs, M. aeruginosa upregulates the expression of genes related to the biosynthesis of the precursor β-carotene, further driving β-cyclocitral production. This study first confirms the synergistic effect between pipeline corrosion and chlorination, which aggravates algal odor pollution. The elucidated underlying mechanism provides a new theoretical basis for the precise control of odor risks in drinking water distribution networks.
Abstract Fluoroquinolone antibiotics (FQs) are a class of antibiotics frequently detected in wastewater treatment plants. However, the response of nitrifying systems to combined FQs exposure remains unclear. This study investigated the effects of combined exposure to ciprofloxacin, norfloxacin, and enrofloxacin on a biological nitrification system, with a focus on the long-term impact of different FQs concentrations (0.12 and 1.2 mg/L). The results showed that low-concentration FQs caused slight inhibition of nitrification, followed by a rapid recovery of nitrification performance. In contrast, high-concentration FQs significantly inhibited nitrite oxidation activity, leading to the accumulation of effluent NO2−-N at 22.79 mg/L. This system maintained activated sludge stability primarily by secreting protein components and optimizing microbial community structure. High-concentration FQs disrupted the nitrification process mainly by suppressing the growth and metabolism of Nitrospira. KEGG metabolic pathway analysis revealed that FQs exposure downregulated carbon metabolism in the system, while promoting oxidative phosphorylation pathways involved in energy generation and electron transfer, which played a critical role in maintaining system stability and resisting FQs stress. This study provided a mechanistic understanding of the metabolic adaptation of biological nitrification under different stresses, which was significant for its application in actual FQ-contaminated wastewater treatment.
Abstract Microplastics (MPs) and heavy metals (HMs) have emerged as pervasive and co-occurring contaminants in aquatic ecosystems, posing escalating threats to environmental integrity, food security, and public health. This review synthesizes current knowledge on the sources, environmental distribution, interactions, bioaccumulation, and trophic transfer of MPs and HMs within aquatic food webs. Evidence indicates that MPs function not only as persistent pollutants but also as highly effective vectors for metal adsorption, transport, and release, altering metal speciation, bioavailability, and toxicity. Across multiple trophic levels, from plankton and benthic organisms to fish and apex predators, MP–metal interactions facilitate contaminant uptake, enhance trophic transfer, and increase internal exposure burdens. Mechanistic studies reveal that these complexes induce oxidative stress, inflammatory responses, cellular damage, and genotoxicity through adsorption–desorption dynamics and biological membrane interactions. Advances in spectroscopic and analytical techniques have improved contaminant detection; however, significant challenges remain regarding methodological standardization, quantification accuracy, and nanoplastic characterization. Current evidence suggests that seafood consumption represents a major pathway of human exposure, raising concerns about chronic health effects. Addressing critical knowledge gaps through harmonized methodologies, improved monitoring tools, and integrated risk assessment frameworks is essential for developing effective mitigation strategies and safeguarding aquatic ecosystems and human health.
