环境•农林最新文献

Denitrification in suspended sediments (SPS) plays a critical role in nitrogen removal within aquatic systems, yet the influence of pollution gradients on this process remains poorly understood. This study investigated denitrification performance and microbial metabolic adaptations across SPS from pollution-defined riparian zones (20 m near-shore/L20, 40 m mid-shore/L40, 100 m far-shore/L100) in Meiliang Bay of eutrophic Lake Taihu. Results showed a clear contamination gradient: nutrients and heavy metals decreased successively from near-shore (highest) to mid-shore to far-shore (lowest). Notably, SPS in L40 had the higher N₂ and N₂O release rates than L20 and L100, despite intermediate pollution levels, suggesting non-linear relationships between contamination magnitude and denitrification efficiency. Compared with L20 and L100, L40 sediments exhibited superior carbon metabolism (EMP/PPP), driving elevated activities of denitrifying enzymes (NAR, NIR, NOS) and higher abundances of associated functional genes (narG, nirS, nosZ). This demonstrates that SPS denitrification is governed not simply by pollution magnitude but by pollution-driven microbial metabolic reconfiguration. This study provides novel insight into SPS-denitrification performance in lakeshore zone with different offshore distances, with critical implications for managing eutrophic and metal-contaminated aquatic ecosystems.

Ground-level ozone (O₃) pollution is a major environmental challenge facing the Yangtze River Delta(YRD) region during the summer and autumn seasons. However, the vertical structure of ozone around large water bodies and its association with the planetary boundary layer (PBL) remain unclear. As a key interface between the Earth's surface and the free atmosphere, the PBL plays a crucial role in ozone formation, dispersion, and vertical transport, necessitating further investigation. This study utilized ozone, wind profilings, ozone precursor NO₂, and concurrent meteorological observation data from July to December 2023 along the eastern shore of Lake Chaohu to systematically analyze the distribution characteristics of ozone and its precursor NO₂ and their interactions with the PBL.The results indicate that: (1) The eastern shore of Chaohu Lake generally meets the standards for a Class I area. Notably, the period from August to October experiences a high incidence of ozone pollution, with daily peak concentrations occurring at 15:00. (2) Correlation analysis revealed that surface meteorological factors such as temperature, sunshine, and air pressure significantly influence ozone levels. During the transition between northeast and southeast winds, ozone-rich air masses from the YRD are advected into the airspace over Lake Chaohu, exacerbating the accumulation of pollutants and enhancing ozone production. (3) High ozone concentrations on polluted days are closely related to the vertical structure of the PBL under stable atmospheric circulation conditions. During such periods, the PBL exhibits higher temperatures, lower wind speeds, and reduced relative humidity. Additionally, the presence of a stabilization layer between 1500 and 3000 m contributes to elevated ozone concentrations below 1300 m. Furthermore, vertical transport through the pollution belt within the height range of 1000 to 1500 m significantly contributes to ozone exceedances. (4) Vertical velocity (ω) under stable weather conditions exacerbates surface pollution by vertically transporting ozone within the boundary layer downward to the surface, and there are temporal differences in the effects of vertical wind shear (VWS) on ozone: weak VWS before 09:00 promotes the accumulation of the precursor NO₂, whereas small VWS after 12:00 increases the risk of surface ozone pollution. In summary, surface ozone concentration is regulated by local photochemical reactions, PBL dynamical structure and regional weather systems at multiple scales. This study reveals for the first time the coupling mechanism between the vertical distribution of ozone and the PBL in the middle and lower reaches of the Yangtze River lakes region, which provides a key scientific basis for the optimization of cross-regional ozone pollution prevention and control strategies.

Fresh leaves of Wrightia tinctoria plant is used by traditional healers in India for wound healing. Even though few research studies conducted on the wound healing property of dry leaves, no scientific proof available for fresh leaf extract of W. tinctoria. The present work aims to analyse the phytochemical components in the fresh leaves of W. tinctoria and also to investigate the wound healing potential in excision wound model. The methanolic extract of fresh leaves possess high levels of phytochemical compounds and the GC-MS analysis indicated the presence of major phytochemicals 8-prenylnaringenin, bilobalide and trans-cinnamic acid. Methanolic extract recorded superior antioxidant, anti-inflammatory and antibacterial activities than other solvent extracts and also protected from intracellular generation of ROS in PBMC cells. Further, it induced angiogenesis in CAM model and found to be safe based on MTT assay. In vivo studies revealed that ointment prepared from methanolic extract of W. tinctoria fresh leaf healed the wound faster (100%) than betadine-treated on 13th day. Hence, methanolic extract of fresh leaves of W. tinctoria could be explored as potential candidate for the development of green and safe wound healing drug.

In this study, the adsorption of Astrazon Blue and Astrazon Red, which are cationic dyes commonly used in the textile industry, from aqueous solution onto commercial activated carbon has been investigated. The effect of various parameters, including initial dye concentration, temperature, stirring speed, contact time, adsorbent dosage, and pH, on the adsorbed dye amount has been investigated using a Taguchi experimental design. For both dyes, the maximum amount of dye adsorbed and the highest calculated signal-to-noise ratio were found to be obtained in adsorption experiments with the following conditions: initial dye concentration of 300 mg/L, contact time of 180 min, initial pH of 9, temperature of 313 K, stirring speed of 170 rpm, and adsorbent dosage of 0.05 g/100 mL. In the determined optimum experimental conditions, the means of adsorbed dye amounts for Astrazon Blue and Astrazon Red were found to be 586.0 and 583.3 mg/g, respectively. It was determined that the equilibrium adsorption data showed a good fit to the Langmuir and Redlich-Peterson adsorption isotherm models. On the other hand, thermodynamic analysis revealed that the adsorption of both dyes on the activated carbon surface occurs with negative Gibbs free energy changes and positive adsorption enthalpy and entropy changes.

Indoor air pollution from solid fuel combustion is a major health risk in developing nations. In Tanzania, over 80% of households rely on biomass and fossil fuels for cooking. While transitions to cleaner fuels are occurring, kerosene remains widely used in urban areas like Dar es Salaam. This study employed cross-sectional techniques among 59 households randomly selected from Mbagala, Dar es Salaam, to characterize indoor air quality and self-reported respiratory symptoms from kerosene and liquefied petroleum gas (LPG) cooking. Indoor concentrations of carbon monoxide (CO), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and particulate matter (PM10) were measured using portable analyzers during morning and evening cooking sessions. Questionnaires gathered data on household demographics, cooking practices, housing characteristics, and self-reported health symptoms. Compared to LPG stoves (n = 28), kerosene stoves (n = 31) emitted significantly higher indoor levels of CO (mean 56 ± 8 vs. 18 ± 1.2 ppm), NO₂ (3.6 ± 0.6 vs. 1.4 ± 0.22 ppm), and SO₂ (2.8 ± 0.4 vs. < 0.1 ppm) exceeding WHO guidelines. Poor ventilation was common. Time spent cooking and household size correlated positively with pollutant concentrations (p < 0.05). Common health issues reported included cough (65%), asthma (30%), and chest pain (25%). Kerosene use was associated with higher indoor air pollutant concentrations and a higher prevalence of self-reported respiratory symptoms than LPG. Interventions are needed to accelerate transitions to cleaner fuels and improve household ventilation. Strategic investments could help reduce exposure and disease burden from indoor air pollution in the study area and other places with similar challenges.

Co-occurrence of heavy metals and plastic-derived pollutants represents a novel challenge for agroecosystem sustainability, yet the mechanistic interplay between biochar (BC) amendments, microplastics (MPs) and cadmium (Cd) remains largely unresolved. A controlled greenhouse factorial experiment arranged in a completely randomized factorial design with six replicates per treatment was conducted to elucidate the BC-MPs-Cd interactions in a loamy slightly neutral soil cultivated with wheat (Triticum aestivum L.). Treatments included two Cd levels (0, 10 mg kg⁻¹), three MPs doses (0, 1, 2% w/w) and two BC rates (0, 1% w/w). BC application markedly increased soil pH (up to 8.11) and organic matter, while reducing DTPA-extractable Cd by up to 36% under Cd10MP2, indicative of pH-driven sorption and precipitation processes. MPs, in contrast, enhanced Cd mobility in a dose-dependent manner in BC-free soils. Elevated Cd bioavailability under Cd10 + MPs treatments resulted in substantial increases in shoot and grain Cd concentrations (20.2 and 4.00 mg kg⁻¹, respectively) and concomitant reductions in biomass and grain yield (15–26% decreases), whereas BC partially mitigated these effects by lowering tissue Cd accumulation (~ 12% reduction). Nitrogen dynamics remained largely unaffected, while Zn availability exhibited secondary yet significant shifts. PCA revealed distinct clustering along Cd mobility versus plant performance axes, reflecting the contrasting regulatory roles of BC and MPs. Overall, BC functioned as a robust chemical buffer against Cd stress even under MPs presence, whereas MPs exacerbated Cd bioavailability and phytotoxicity. These findings provide critical insights into multi-contaminant interactions and underscore the necessity of integrated remediation strategies in contaminated agricultural soils.

Graphical Abstract

In the nitrogen cycle of agricultural ecosystems, ammonia volatilization is an important way of nitrogen loss and makes a significant contribution to nitrogen deposition. In South China, high nitrogen deposition threatens both ecological balance and food security. This study assessed the effects of organic fertilizer substitution, optimized irrigation, and reduced tillage on crop yield, crop nitrogen use efficiency (NUEc), and NH₃ volatilization in rice, maize, and vegetables. We also examined the relationship between NH₃ volatilization and nitrogen deposition. Organic fertilizer substitution improved agricultural performance, increasing crop yields by 3.0–5.3%, enhancing NUEc by 2.2–3.6%, and reducing NH₃ emissions by 7.9–21.8%. Optimized irrigation resulted in a 1.8–4.2% increase in yield, a 1.4–5.1% improvement in NUEc, and an 8.4–13.7% reduction in NH₃ volatilization. Conversely, reduced tillage had no significant impact on crop productivity, yet it was associated with reduced NUEc and increased NH₃ emissions. Wet deposition accounted for 80.0–83.3% of the total nitrogen deposition flux in the experimental area, with ammonium nitrogen as the dominant form. NH₃ volatilization was positively correlated with nitrogen deposition (R² = 0.278, p < 0.05) (Fig. 7). Organic fertilizer substitution and shallow wet irrigation enhanced ammonium-to-nitrate conversion by increasing soil organic matter and prolonging water residence time, thus improving NUEc and reducing NH₃ volatilization and nitrogen deposition.It could contribute to ensuring food production safety and improving regional environmental quality in South China.