Efficient treatment of chemical industry park tailwater remains challenging owing to the presence of refractory and toxic pollutants with low biodegradability. Although coupling advanced oxidation with biodegradation represents a promising strategy, conventional approaches often suffer from high operational costs or limited efficiency resulting from excessive or insufficient oxidation. To overcome these limitations, a pilot-scale system for the simultaneous coupling of ozonation and biodegradation (SCOB) was developed using an inner-cycle fluidized bed with a coaxial double-tube configuration, enabling near-synchronous spatial–temporal integration of the two processes. Under optimal operating conditions (ozone dosage of 15 mg/(L·h) and hydraulic retention time of 18 h), the SCOB system achieved ~70% chemical oxygen demand removal, surpassing standalone ozonation and biological processes by ~13% and ~37%, respectively. The system also achieved substantial reductions in chroma (~87%), turbidity (~94%), and ultraviolet absorbance at 254 nm (~89%) while effectively transforming refractory aromatic and sulfur-containing dissolved organic matter into more biodegradable fractions. Fourier-transform ion cyclotron resonance mass spectrometry analysis revealed significant decreases in aromaticity and unsaturation indices, confirming efficient degradation of recalcitrant organic compounds. Toxicity assays further demonstrated marked reductions in biotoxicity toward plants, luminescent bacteria, and zebrafish. Metagenomic analysis indicated enrichment of functional microbial genera (e.g., Hyphomicrobium, Aequorivita, and Roseovarius) and metabolic genes associated with aromatic and sulfur compound degradation. These findings demonstrate that the inner-cycle fluidized SCOB system effectively integrates ozone oxidation and biodegradation, offering a robust and efficient strategy for advanced treatment of chemical industry tailwater.
Polybrominated diphenyl ethers (PBDEs) predominantly reside in solid matrices such as sediments and soil owing to their strong hydrophobicity. The use of organic solvents in pre-extraction and treatment processes to effectively eliminate PBDEs from solid matrices is not only detrimental to the environment but decreases the debromination efficiency of PBDEs. Herein, the surfactants sodium dodecylbenzenesulfonate (SDBS) is introduced for the treatment of 2,2',4,4'-tetrabromodiphenyl ether (BDE47) in water. In the catalytic system based on “Pd2+ + N2H4•H2O”, the addition of 50 mmol/L SDBS achieved complete BDE47 degradation (20 mg/L) in water within 60 s, with 100% debromination efficiency. By contrast, the debromination efficiency of BDE47 was only 8% when using pure methanol as the solvent. The introduction of SDBS increased BDE47 solubility in water, facilitating its debromination, which not only avoided the use of organic solvents but also accelerated the chemically catalytic reduction of BDE47 via active hydrogen atoms (H•) due to the higher hydrogen-bond donor capability of water compared to that of organic solvents. In addition, in situ decoration of Pd nanoparticles with SDBS improved their dispersion and amphiphilicity, promoting the surface adsorption of hydrophilic N2H4•H2O and hydrophobic BDE47, which enhanced H• generation and its transfer to BDE47.
Lakes regulate the global carbon cycle, with sediment dissolved organic matter (DOM) playing a pivotal role in organic carbon (OC) sequestration. However, the effects of imbalanced nitrogen (N) and phosphorus (P) inputs on sediment DOM dynamics and carbon sequestration remain unclear. We conducted short-term microcosm experiments using muddy (MS) and sandy (SS) lake sediments under N/P input ratios of 5:1, 15:1, and 45:1. The results revealed that MS sediments were enriched with protein-like (~50%) bioavailable DOM, whereas SS sediments were dominated by aromatic DOM (~90%), exhibiting greater humification and superior carbon retention. Protein-like components responded rapidly to nutrient changes, whereas humic-like substances exhibited greater persistence. Notably, elevated N inputs accelerated the degradation of recalcitrant humic substances (C4) according to MS. Mantel tests revealed that sedimentary organic carbon (SOC) in MS was highly significantly positively correlated with TN (p < 0.001), whereas that in SS was highly significantly positively correlated with TP (p < 0.001). PLS‒SEM analysis further revealed that the N/P input ratio inhibited carbon sequestration in both sediment types through distinct pathways: In muddy sediments, the N/P input ratio primarily altered the DOM composition, whereas in sandy sediments, the N/P input ratio regulated both the DOM properties and nutrient availability. Our results demonstrate that sediment type regulates DOM transformation and early-stage carbon retention under N/P imbalance, with muddy and sandy sediments exhibiting fundamentally different response pathways. These findings highlight the importance of incorporating sediment heterogeneity into assessments of lake carbon cycling and nutrient management under eutrophication pressure.
Alkylphenols (APs), known as endocrine-disrupting chemicals, are vital antioxidants in daily consumer products. As a municipal solid waste destination, landfilled waste might become a sink and a source of APs. In this study, we first confirmed the occurrence characteristics of 13 APs in landfilled waste from 2012 to 2020 at depths of 1–55 m. The total APs concentration in landfilled waste with different depth varied from 19.58 to 248.43 μg/g. The AP monomer concentration varied from 0.17 ± 0.24 to 146.92 ± 101.28 μg/g. From time series, the total AP concentration ranged from 19.14 ± 10.08 μg/g to 200.63 ± 88.47 μg/g. The landfilling time (p < 0.05) had a significant effect on the AP concentration. The Quantitative Structure Activity Relationships (QSAR)-based the Ecological Structure Activity Relationships (ECOSAR) tool was used to evaluate ecological risks. The results indicated that from 2012 to 2020, APs posed moderate or high risks to the landfilling area. This study highlights the prominent existence of APs in landfilled waste and draws attention to the control of APs as contaminants of emerging concern for the waste sector.
Land-use gradients altered dissolved organic nitrogen (DON) sources. However, the response of riverine DON remains unclear due to interactions between bioavailable fractions and plankton communities. This study examined DON dynamics, bioavailable components, optical properties, and plankton communities (phytoplankton and bacteria) across two hydrological seasons along a river continuum with forest-affected upstream, agricultural midstream, and urban downstream reaches. DON increased downstream from 0.14 to 0.22 mg/L during the dry season but decreased from 0.17 to 0.12 mg/L during the wet season. The proportion of bioavailable DON (urea and dissolved total amino acids) exhibited negative correlations with DON (p < 0.0001), suggesting that bioavailable fractions drive DON variation along land-use gradients. Spectral characterization showed that downstream sites contained more autochthonous DON, associated with highly bioavailable phytoplankton inputs in the wet season and less bioavailable sediment release in the dry season (p < 0.05). Bacterial community composition exhibited pronounced spatial shifts along the land-use gradient, with higher DON bioavailability characterized by an increased dominance of Pseudomonadota. Ammonification driven by Pseudomonadota primarily mediated bioavailable DON consumption (p < 0.001), and nitrate production was the dominant pathway of DON mineralization. This study revealed that land-use gradients drove DON dynamics through changes in bioavailable fractions, providing critical insights for sustainable water management.
The widespread contamination of heavy metals (HMs) in mining areas poses severe and persistent threats to ecosystem and human health, necessitating advanced tools for predictive risk assessment. In this study, we conducted quarterly sampling over one year across 62 farmland soil sites and 22 paired irrigation water and sediment sites in a mining area of South China, and measured concentrations of eight HMs (As, Cd, Pb, Zn, Cu, Ni, Hg, and Cr). A Monte Carlo-optimized Level IV fugacity model was employed to simulate HM transport and assess ecological risks across environmental compartments. The results showed that Hg and Cd posed the highest ecological risks among all HMs, with their potential ecological risk index values in sediment reaching 195.11 and 126.93, respectively. Transfer flux analysis revealed that atmospheric deposition dominated inputs to water (15.64%–95.31%) and soil (99.89%–99.99%), while water-to-sediment transfer accounted for 99% of water outputs, making sediment the predominant sink. Scenario analysis indicated that a 50% emission reduction would delay Hg risk in sediment from reaching the extremely high level (RI ≥ 320) until 2040 and maintain Cd in soil within the low risk range (RI ≤ 40). However, historical contamination would sustain Hg risk in sediment above RI ≥ 160 under all scenarios. Overall, this research establishes a crucial dynamic modeling framework for forecasting long-term ecological risks and designing targeted, metal-specific control strategies in mining-affected regions.
Cadmium (Cd) contamination in industrially polluted soils poses persistent environmental risks because of its high mobility and toxicity. In this study, a carboxymethyl chitosan (CMCS)-assisted enzyme-induced carbonate precipitation (EICP) strategy was developed to increase Cd stabilization while maintaining enzymatic activity under high Cd stress. Batch experiments optimized CMCS and urea dosages at 4 g/kg soil, achieving a > 90% reduction in extractable Cd and effectively preserving urease activity. Long-term incubation and column leaching tests further demonstrated that EICP induced a pronounced transformation of Cd from labile fractions to carbonate-associated fractions, resulting in markedly reduced Cd release under both acidic (pH 3.2) and elevated hydraulic loading conditions. Mineralogical and structural characterization provided direct evidence for in situ carbonate precipitation and concomitant improvements in soil aggregate stability. Pot experiments using Pennisetum purpureum as a model plant revealed significant increases in plant biomass and soil nitrogen availability after EICP treatment. High-throughput sequencing analyses indicated that EICP moderated deterministic community assembly processes and promoted higher microbial diversity and network connectivity. Although microbial network robustness remained comparable across treatments, Cd contamination substantially increased network vulnerability, which was effectively alleviated after EICP remediation. Overall, CMCS-assisted EICP enables effective and durable Cd stabilization while simultaneously improving soil physicochemical properties and microbial community organization, highlighting its potential as an eco-compatible remediation approach for Cd-contaminated industrial soils.