Journal of Environmental Engineering Technology•2026•DOI: 10.13205/j.hjgc.202604003
Emerging contaminants (ECs) in wastewater from urban transportation infrastructure remain poorly characterized. This study employed high-resolution mass spectrometry (HRMS)-based non-target screening to systematically identify the composition and spatial distribution of ECs in wastewater from three functional zones of a metro maintenance depot: storeroom (S1), office/residential area (S2), and final discharge outlet (S3). A total of 417 contaminants were detected, spanning eight categories including industrial materials, pharmaceuticals, pesticides, and natural products. Among these, 48 substances were identified with Level 1 confidence via spectral matching. Pesticides exhibited the highest detection frequency and concentration levels, representing the primary contaminant load. Semi-quantitative concentration heatmaps of 24 pesticides revealed significant spatial variation: S2 showed the highest number and concentration of contaminants, reflecting inputs from landscaping and vector control; S1 and S3 showed lower levels, indicating dilution, migration, and attenuation. Representative pesticide bifenox displayed a clear concentration gradient (S2 > S1 > S3), suggesting transport mechanisms such as surface runoff, hydraulic transfer, and sorption. These findings underscore the complexity and diversity of EC sources in metro depot wastewater, highlight the need to prioritize pesticides in regulatory management, and provide fundamental data for understanding EC environmental behavior and informing water environment risk assessment.
Journal of Environmental Engineering Technology•2026•DOI: 10.13205/j.hjgc.202605013
The escalating eutrophication of aquatic systems has intensified algal blooms, leading to substantial release and accumulation of algal-derived dissolved organic matter (ADOM), which profoundly influences carbon cycling and pollutant transport. Iron minerals, particularly ferrihydrite, are recognized as critical mediators of DOM sequestration, yet the adsorption fractionation of ADOM under varying environmental conditions remains poorly understood. This study systematically investigated the effects of pH (2.0–10.0) and initial dissolved organic carbon (DOC) concentration (2–100 mg C/L) on the adsorption capacity and selectivity of ADOM onto ferrihydrite, employing UV-Vis spectroscopy and excitation-emission matrix fluorescence with parallel factor analysis (EEM-PARAFAC). Results demonstrated that adsorption capacity increased with pH from 2.0 to 7.0, reaching a maximum of 21.59 mg C/g at pH 7.0, followed by a decline at pH > 7.0 due to enhanced electrostatic repulsion. Within the environmentally relevant pH range of 3.0–9.0, selective fractionation intensified with increasing pH, favoring highly aromatic, high-molecular-weight chromophoric DOM (CDOM) and protein-like/aromatic amino acid fluorescent DOM (FDOM) with high humification and autochthonous characteristics. With increasing initial DOC concentration, adsorption exhibited non-linear growth, with preferential uptake of low-aromaticity, high-molecular-weight CDOM and protein-like FDOM of lower humification and stronger autochthonous features. These findings elucidate that ferrihydrite can effectively sequester reactive ADOM components via pH- and concentration-dependent selective adsorption, potentially altering DOM composition and reactivity in eutrophic waters, thereby providing fundamental data for understanding iron mineral-mediated internal carbon sequestration.
Journal of Fuel Chemistry and Technology•2026•DOI: 10.1016/S1872-5813(26)60642-1
Inherent minerals significantly influence the thermal conversion of coal, yet the interaction mechanisms among minerals affecting tar generation during pyrolysis remain unclear. This study investigates the effect of acidic mineral components on the behavior of ion-exchangeable Ca2+ during coal pyrolysis. Coal samples were prepared via HCl and HCl-HF acid washing followed by Ca2+ ion exchange. Pyrolysis was conducted in a fixed-bed reactor. Acid washing effectively reduced ash content but also decreased organic element contents (carbon, hydrogen). Loading ion-exchangeable calcium enhanced the thermal weight loss rate in the 500–550 °C range, shifting the peak temperature from 530 °C to 514 °C. At a final pyrolysis temperature of 600 °C with slow heating, kaolinite in acidic minerals underwent dehydroxylation to form metakaolin. The content of small aromatic rings (<6 rings) in char from Ca-loaded coal was lower than that from acid-washed coal without Ca. Coexistence of acidic minerals with ion-exchangeable Ca increased aliphatic hydrocarbon content in tar: YL-HCl-Ca reached 21.98% versus 13.60% for YL-De-Ca. Acidic mineral components inhibit the adverse effect of ion-exchangeable Ca2+ on tar lightening. These findings provide insights into mineral interactions during pyrolysis, aiding in optimizing coal conversion processes for improved tar quality.
Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2026030202
High nitrogen (N) inputs, low N use efficiency, and substantial greenhouse gas emissions constrain sustainable double-cropping rice production in the middle and lower reaches of the Yangtze River. To evaluate whether humic acid urea (HAU) can reconcile yield stability with N reduction and carbon mitigation, a field experiment was conducted in a double-cropping rice system. Five treatments were established: conventional urea at the recommended N rate (U), HAU at the recommended N rate (HAU), conventional urea with a 20% reduction in N input (U-20), HAU with a 20% reduction in N input (HAU-20), and a no-N control (CK). Rice yield, N uptake and utilization, and the full life-cycle carbon footprint were quantified. Results showed that HAU significantly increased double-cropping rice yield by 6.46% (early rice) and 8.76% (late rice) compared to U (P < 0.05). HAU-20 maintained yield equivalent to U, while U-20 significantly reduced yield. HAU-20 significantly improved nitrogen fertilizer apparent utilization rate, agronomic efficiency, and partial factor productivity. Specifically, apparent utilization rate increased by 9.24 percentage points (early rice) and 7.80 percentage points (late rice); agronomic efficiency increased by 18.51% and 26.69%, and partial factor productivity by 22.79% and 25.58% for early and late rice, respectively (P < 0.05). Life-cycle carbon footprint was significantly reduced by 26.25% (early rice) and 40.38% (late rice) under HAU-20 compared to U, with per-unit product carbon footprint reduced by 0.22 t CO2-eq·t−1 and 0.86 t CO2-eq·t−1, respectively. The reduction was primarily attributed to decreased CH4 and N2O emissions: early rice CH4 and N2O cumulative emissions decreased by 28.92% and 44.34%, and late rice by 44.46% and 63.85% (P < 0.05). In conclusion, HAU with 20% N reduction sustains yield, enhances N use efficiency, and significantly lowers carbon footprint, offering a viable path for green and low-carbon double-cropping rice production.