环境•农林最新文献

Plant configuration and earthworms play an important role in water purification and greenhouse gas emissions in constructed wetlands (CWs). However, the impact of earthworm density on greenhouse gas emissions across different plant configurations has not been explored. In this study, four wetland plant species, Canna indica, Lythrum salicaria, Oenanthe javanica, and Typha orientalis, were selected for monocultures. Under each monoculture, three earthworm densities (control, low, and high densities) were conducted to explore the effects of earthworm density on greenhouse gas emissions in CWs with different plant configurations. The results showed that: (1) in systems without earthworms, the CO₂ emission from O. javanica monoculture was 69.9% lower than that from C. indica monoculture; the CH₄ emission decreased with the increasing earthworm density across all plant configurations, with high earthworm density resulting in negative CH₄ emission. (2) In systems with low and high-density earthworms, C. indica exhibited the highest biomass among four monocultures. However, earthworm density did not significantly affect plant biomass under the same plant configuration. (3) In systems without earthworms, the substrate organic carbon (SOC) of O. javanica monoculture was 18.94% and 4.93% lower than that in T. orientalis and C. indica monocultures, respectively; For L. salicaria monoculture, the SOC was 35.69% and 40.59% lower in systems without earthworms compared to those with low and high-density earthworms, respectively. (4) In systems without earthworms, the global warming potential (GWP) value, including GWP_{CH4+CO2+N2O+SOC}, GWP_{non-CO2+AGB+SOC}, and GWP_{CH4+CO2+N2O+AGB+SOC} were lowest in L. salicaria monoculture among four monocultures. Moreover, in L. salicaria monoculture, the GWP_non-CO2+SOC of systems without earthworms was 36% and 40.7% lower than in systems with low and high-density earthworms by, respectively. These results indicate that adding high-density earthworms can reduce CH₄ emissions in constructed wetlands with different plant configurations. L. salicaria monoculture without adding earthworms demonstrated a low global warming potential.

Straw return is a sustainable agricultural strategy aimed at raising soil organic carbon (SOC), but tends to stimulate nitrous oxide (N₂O) emissions, potentially counteracting gains in SOC sequestration. Nevertheless, knowledge gaps remain on how long-term different forms of straw incorporation (direct straw return or pyrolyzed to biochar) affect N₂O production and reduction, and interactions with associated key nitrogen (N)-cycling microbial communities. Here, the emission rates and proportions of N₂O and N₂ emissions were quantified using a 13-year field trial with sequential incorporation of straw or straw-derived biochar, and interactions with key functional genes were assessed by metagenomic sequencing. Results revealed that incorporation of straw and biochar increased N₂O emission rates by 2.55 and 0.54 folds, while that of N₂ by 6.41 and 9.77 folds, respectively, compared with conventional fertilization. Correspondingly, the N₂O/(N₂O + N₂) ratios were reduced by 10.75% and 39.74% with straw and biochar treatments. Higher N₂O emissions with straw incorporation were primarily driven by concurrent increase in labile C and N sources with nitrate and nitrite reducers (narG, narH, nirK, nirS, norB) outweighing the N₂O reducer (nosZ). In contrast, biochar incorporation decreased nitrate levels, increased electron conductivity and the N₂O reducer (nosZ), which accelerated N₂ emissions and reduced the N₂O/(N₂O + N₂) ratio. Moreover, reduced N₂O/(N₂O + N₂) ratios were closely associated with altered denitrifier communities, with genera belonging to Acidobacteriota being the key contributors to biochar incorporation, and Pseudomonadota being the dominant contributors to straw. Overall, biochar incorporation was more efficient in reducing global warming potential and increasing SOC sequestration, as evidenced by lower N₂O/(N₂O + N₂) ratios and higher SOC levels. This work provides valuable insights designing net-zero C strategies towards sustainable agricultural C sequestration and greenhouse gas mitigation to address the challenges posed by global climate change.

Understanding the behavior of pathogenic bacterial groups from domestic wastewater in surface water is critical to improving sanitation risk assessment and supporting effective policy implementation. Despite their importance, their behavior in freshwater environments is not fully understood. This study examined the behavior of pathogenic bacterial groups frequently found in domestic wastewater–Aeromonas, Arcobacter, and Mycobacterium—in freshwater microcosms containing domestic wastewater with different initial ammonium-nitrogen (NH₄⁺-N) concentrations (2, 5, and 15 mg N L⁻¹). Digital polymerase chain reaction (dPCR) assays with propidium monoazide (PMA) pretreatment were used to evaluate the behavior of viable targeted bacteria. Aeromonas and Arcobacter decayed quickly after the experiment began, with typical first-order decay constants of 0.718 to 0.820 day⁻¹ and 1.14 to 1.19 day⁻¹, respectively. These rates were comparable or higher than those of Escherichia coli, an indicator of fecal contamination (0.586–0.680 day⁻¹). Conversely, the abundance of Mycobacterium increased over the course of the 7-day experiment. The decay or growth of the target bacterial groups in the microcosms under aerobic conditions was not affected by varying NH₄⁺-N concentrations. Sequencing of the near-full-length 16S ribosomal ribonucleic acid (16S rRNA) gene amplicons with PMA pretreatment revealed that the primary Aeromonas and Arcobacter populations in the initial microcosms were pathogenic species relatives. Conversely, the major Mycobacterium populations thriving in the microcosms were presumably uncultured species with low 16S rRNA gene sequence similarity (< 98.65%) to the cultured species. This study provides insights to improve sanitation risk assessment and promote suitable policy implementation.

Black carbon aerosols and PM2.5 have been identified as one of the major factors responsible for the ambient air quality index in Jamshedpur. The real-time measurement of BC concentration is determined with the help of an Aethalometer (AE-33), which was analyzed from November 2022 to April 2023. In the present study, we have compared the aerosol parameters during haze (Nov-Jan) and normal days (Oct, Feb-May) periods. We estimated the average mass concentration of BC, PM2.5 and AQI during haze days (HD) and normal days (ND), respectively. BC concentrations showed significant temporal variations with around 6.25 ± 3.05 and 2.52 ± 2.75 μg m − 3 during HD and ND, respectively. While PM2.5 and AQI concentrations in HD were found to be 264.64 ± 58.8 and 267.84 ± 56.72 μg m − 3, which were double of 130.19 ± 60.1 and 141.98 ± 52.44 μg m − 3, respectively, during ND. The highest monthly concentration of BC, PM2.5 and AQI was noticed in December at 8.35, 291.9 and 298 μg m − 3, respectively. Large-scale energy production in industries can consume coal and petroleum as primary fuels, which may be a major reason for the high concentrations. Due to low mixing height during winter, these emissions are not spread properly. Hence, higher concentration was found in December. The values for BC/PM2.5 were observed as 2.37% with a range from 0.54 to 4.4% and 2.48% (0.5 to 21.78%) during HD and ND, respectively. The study determined the source apportionment of BC with biomass dominance found in HD. The % BB was obtained around 53.1% throughout haze session, which was approximately 1.57 times higher than normal day (33.77%). In winter, burning wood and other solid fuels to warm the atmosphere may increase the contribution of BB to BC emissions. Furthermore, the backward trajectories calculated that air masses were concentrated within the IGP regions at lower altitudes during the HD while there was a diverse circulation of air parcels throughout the ND. Air masses were majorly coming to the receptor site from west India in ND. GIOVANNI NASA satellite model proved that surface mass concentrations of BC and PM2.5 were observed higher over IGP areas as well as other parts of India during HD with respect to ND.

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Natural coagulants are emerging as effective alternatives to inorganic coagulants in wastewater treatment due to their high coagulation-flocculation activity, abundance, cost-effectiveness, and biodegradability. Despite their potential, research has largely been limited to laboratory-scale experiments, with few studies exploring pilot-scale applications. This study investigates pine cones, a novel and underutilized waste material, as a bio-coagulant for wastewater treatment plants (WTPs). The active coagulating agent was extracted from pine cones treated with a 0.5 M sodium chloride (NaCl) solution. Characterization was performed using Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and chemical analysis, revealing significant quantities of coagulating agents responsible for effective coagulation. A jar test was initially conducted to determine the optimal coagulant dosage, initial pH, and settling time for the coagulation-flocculation process. The process was modeled and optimized for turbidity, chemical oxygen demand (COD), and phosphate removal using response surface methodology (RSM) with a Box Behnken design (BBD). The optimal conditions identified were a 10 ml/L coagulant dosage at pH 10 and a settling time of 115 min. Experimental data and model predictions showed good agreement, with R² values of 99.12%, 93.52%, and 98.11% for turbidity, COD, and phosphate removal, respectively. Jar tests under these conditions achieved removal efficiencies of 98.81%, 72.02%, and 86.44% for turbidity, COD, and phosphate. The optimized conditions were then applied on a pilot scale, showing removal efficiencies of 97.77%, 71.35%, and 88.6% for turbidity, COD, and phosphate. Our findings highlight pine cones as an effective, cost-efficient, and eco-friendly alternative for WTPs.

Total petroleum hydrocarbon (TPH) in wastewater has attracted widespread attention for its environmental and biological health hazards. In the research, WY-4 strains with diesel degradation ability isolated from contaminated soil and response surface methodology was used to optimize the degradation conditions of WY-4. Fe-modified biochar (FPB) was used as an immobilized carrier, the environmental factors affecting the degradation of immobilized bacteria (FPBM) were explored and the degradation effect of FPBM was evaluated on real TPH-contaminated wastewater. Furthermore, the potential degradation mechanisms and possible degradation pathways of TPH were also explored. The results demonstrated that WY-4 was identified as Ochrobactrum sp., and its optimal growth conditions were pH 6.8, temperature 28.8°C and NaCl concentration 9.47 g/L. The removal efficiency by FPBM on 10,000 mg/L diesel wastewater was 72.5% and on real TPH-contaminated wastewater was 76.75% in 7 d, which was significantly higher than the degradation effect of free bacteria. The degradation pathway of two representative pollutants, naphthalene and indole, in the real TPH-contaminated wastewater was referred to be the catechol metabolic pathway. The results highlighted the potential of FPB-immobilized bacteria for the remediation of TPH-contaminated wastewater in harsh environments and provided an effective strategy for green remediation treatment of TPH contamination.

Reactive oxygen species (ROS) frequently detected in water systems require thorough investigation due to their widespread occurrence and potential health risks. This study sought to clarify the impact of ROS on zebrafish—a widely-used model organism in aquatic toxicology—and antibiotic-resistant bacteria. We explored how ROS exposure affects zebrafish brain activity, uncovering a notable increase in abnormal cognitive function, which points to possible neurological disruption. Moreover, the elevated ROS production, especially from heavy metals in natural water systems, induces 'oxidative stress,' which not only challenges antibiotic-resistant bacteria but also promotes biofilm formation and facilitates plasmid transfer. Unlike previous studies that primarily focused on heavy metal toxicity, our research highlights the role of free radical generation from metal-environment interactions. The development of innovative toxicity assessment models is imperative for accurately evaluating the ecological risks of these contaminants. This study emphasizes the critical need to understand the dual impact of ROS on zebrafish and antibiotic-resistant bacteria, guiding the development of strategies to mitigate their ecological and public health consequences in aquatic ecosystems.

This study focuses on the innovative production of Bio-Graphene Foams (BGFs) from sustainable resources, aimed at addressing the critical challenge of efficiently removing harmful chlorophenols—specifically 2,4-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP)—from wastewater. In this investigation, we present an innovative and streamlined methodology to address the constraints encountered in the fabrication of biomass-derived Graphene Foams (bGFs). Our primary focus is on customizing their extensive surface area and structural attributes to align with the specific requirements of environmental applications, particularly for the adsorption of chlorophenols. We developed a distinctive BGF with a highly porous, spongy structure and an impressive specific surface area of up to 805 m²/g through a two-step synthetic process. Our method not only enhances the environmental applicability of BGFs but also demonstrates their superior adsorptive capabilities. The adsorption performance of the BGFs was rigorously evaluated, with a focus on capacity, kinetics, and the influence of pH. Comprehensive studies on the effects of pH, contact time, adsorbent dosage, and phenolic content were conducted. The adsorption isotherms for DCP and TCP adhered to the Langmuir model, revealing an outstanding adsorption capacity of 245 mg of pollutant per gram of BGF at an optimal pH of 3–4. Remarkably, BGFs reduced the concentration of phenolic derivatives in water to levels below the World Health Organization’s acceptable limit for human use (0.050 mg/dm³). This research highlights the significant potential of Bio-Graphene Foams as highly effective adsorbents for environmental remediation. The challenges associated with synthesizing such high-performance materials and optimizing their application for wastewater treatment were successfully addressed, marking a substantial advancement in the field.