环境•农林最新文献

Fear of snakes is common not only in humans but also in other primates. Consequently, snakes are salient stimuli associated with prioritized attention, early detection and emotional significance. This has been interpreted as an adaptive evolutionary response of the primate brain to a risk of envenoming by a hidden snake. However, the struggle between mammals and snakes is not one-sided. Humans and carnivores regularly kill snakes, and thus snakes develop deterring defensive behaviour that may directly evoke enhanced fear. Here, we show that snakes depicted in threatening posture evoked on average more fear than those in resting posture. Significantly, African (Somali) and European (Czech) respondents considerably agreed on the relative fear elicited by various snakes. Nonetheless, not all defensive postures are equally efficient. Threatening cobras were perceived as top fear-evoking stimuli, even though most of them are not considered very frightening in resting posture. This effect can be attributed to their conspicuous hooding posture which evolved into an efficient warning signal for mammalian predators. Our result demonstrates that cobras are more effective than other snakes in the ability to evoke human fear by a simple behavioural display—hooding. This can be primarily explained by the behavioural evolution of cobras which successfully exploited pre-existing cognitive mechanisms of mammals. Whether human ancestors cohabiting with deadly venomous cobras further improved their fear response to hooding is uncertain, but likely.

Microplastics (MPs), recently identified as emerging contaminants in environmental and biological systems, currently lack a comprehensive ecological risk assessment in waste disposal environments. This study investigates the presence, abundance, and distribution patterns of MPs in agricultural soils and surface water near the largest waste disposal area in Dhaka, Bangladesh, mainly focusing on assessing ecological risks and identifying potential hazards. MPs were characterized using ATR-FTIR spectroscopy, stereomicroscopy, and SEM–EDX analysis. The agricultural soils were categorized into 5–2 mm, 2–1 mm, and 1–0.5 mm size fractions, concentrating on MPs less than 5 mm in surface waters. The mean abundance of MPs in surface soils was 2800 ± 696.42, 2320 ± 622.09, and 2040 ± 313.05 particles/kg, while in subsurface soil they were 2680 ± 576.19, 2200 ± 570.09, and 1760 ± 443.72 particles/kg for respective size fractions, and 376 ± 57.29 particles/liter in surface water. MPs were significantly correlated with soil moisture, pH, electrical conductivity, organic matter, nitrogen, and phosphorus. The predominant polymers were polyethylene, polypropylene, and polystyrene, mainly in fiber and film forms. The ecological risk evaluation indicated a high risk for surface soil and a medium-to-high risk for subsurface soil of agricultural land and surface water. Plastic mulch, solid waste, surface water irrigation, and organic compost were probably the potential sources of MPs, and their entrance into farmland and adjacent environments should be strictly limited. This study would provide the baseline reference for the current situation on agricultural fields and surface water near waste dumping sites, as well as emphasize the need for strong environmental regulations and effective mitigation techniques to address microplastic pollution.

Graphical abstract

Atrazine, a widely used herbicide in agriculture due to its effectiveness and low cost, is employed to eliminate broadleaf weeds. However, its persistence and mobility in aquatic environments pose significant risks to ecosystems and human health. This emphasizes the urgent need to develop effective methods for its degradation in surface and groundwater. Heterogeneous photocatalysis, activated by visible light, has emerged as a promising solution, enabling the generation of reactive species capable of efficiently degrading organic pollutants. In this study, we designed an innovative ternary photocatalytic composite, composed of g-C₃N₄, graphene, and NiFe₂O₄, to enhance atrazine degradation under visible light in the presence of potassium peroxymonosulfate (PMS). This composite leverages the synergistic properties of its components: g-C₃N₄ efficiently absorbs visible light and generates electrons and holes necessary for degradation reactions; graphene acts as an electronic mediator, facilitating the separation and mobility of photo-excited charge carriers, thereby reducing charge recombination; and NiFe₂O₄ plays a key role in PMS activation, generating sulfate (SO₄•⁻) and hydroxyl (OH•) radicals responsible for atrazine oxidation and degradation. Compared to conventional photocatalysts, this composite offers significant advantages, notably a reduction in bandgap energy to 2.42 eV, thereby enhancing visible light absorption. Irradiation was carried out using a 48 W fluorescent lamp, optimizing the composite’s activation under visible light. Our experimental results show that 97% atrazine degradation was achieved in 5 h under optimal conditions of photocatalyst loading (0.3 g/L) and PMS concentration (1 mM) at ambient temperature. These findings highlight the potential of this material for sustainable treatment of emerging organic pollutants in contaminated waters, addressing the current challenges of water purification.

TiO₂ is one of the most common and well-researched photocatalysts. However, it possesses certain limitations that hinder its research progress and practical application in the degradation of organic pollutants, particularly in the realm of (micro)plastics degradation. The modification of TiO₂ is currently a research hotspot in the photocatalytic degradation of organics. Noble metal Ag, with its unique advantages of safety, environmental friendliness, antibacterial properties, and good electrical conductivity, is an excellent modifier for TiO₂. This study first delved into the enhancement mechanism of Ag on TiO₂ photocatalytic degradation and the mechanisms of Ag/TiO₂ for degrading common organics and microplastics. It also discussed the preparation methods of Ag/TiO₂ complexes, their advantages, disadvantages, and applications of each method. Furthermore, it presented a comparative analysis of the current research status of TiO₂ and Ag/TiO₂ photocatalytic degradation of organics, particularly on (micro)plastics. Finally, it highlighted the limitations and shortcomings of current studies and proposed potential future research directions. This research serves as a guide for the large-scale production of efficient Ag/TiO₂ photocatalysts and the promotion of research on Ag/TiO₂ photocatalytic degradation of microplastics.

In the current research, ferric oxide-chitosan composite (FOCC) was synthesized by loading chitosan with ferric oxide which was obtained from a kind of ferrous sulfate waste liquid by chemical precipitation, and FOCC was used to adsorb the copper(II) ion from polluted water. The effects of copper(II) ion adsorption experimental factors including initial pH, FOCC dosage and contact time on the removal efficiency were determined, and the related copper(II) ion adsorption mechanism was discussed. The copper(II) ion adsorption optimization study was performed through Box–Behnken design (BBD), and the maximum efficiency of copper(II) ion removal reached 99.23% under the optimized adsorption conditions of initial pH = 5.57, FOCC dosage = 2.5 g/L, contact time = 15 min. The kinetics of copper(II) ion adsorption by FOCC fits well with the pseudo-second-order model (R² > 0.9920), indicating that the copper(II) ion adsorption process belongs chemisorption. The maximum adsorption capacity of FOCC for copper(II) ion is 14.81 mg/g when the temperature is 55 °C. Under the above temperature, the isothermal experiments show that the Langmuir model (R² > 0.9920) is more suitable for describing copper(II) ion adsorption process than the Freundlich model(R² > 0.9504). The adsorption of copper(II) ion onto FOCC is endothermic(({Delta H}^{^circ }<0)) and spontaneous(({Delta G}^{^circ }<0)). In general, the study demonstrates FOCC is a quite promising material for copper(II) ion removal from polluted water.

It is generally accepted that inhibitors are effective in reducing agricultural nitrous oxide (N₂O) emissions from soils irrigated by groundwater. However, it was unclear whether these inhibitors effectively regulate N₂O emissions from soils irrigated with alternative waters, like reclaimed water and livestock wastewater. To clarify this, nitrapyrin, a nitrification inhibitor, and N-(N-butyl) thiophosphoric triamide, a urease inhibitor, were added separately or jointly to the soils irrigated by groundwater, reclaimed water and livestock wastewater through two consecutive cycles of pot experiment. Both the single and combined addition of inhibitors lowered N₂O emissions from soils irrigated with alternative water, while the reduction effect of the combined application decreased relative to that of the single application. The using of combined inhibitors did reduce the enrichment level of nitrification genes and slow down the nitrification process, but the associated relatively high nirS/nosZ ratio potentially discounted its ability to prevent N₂O emissions. Whereas under groundwater irrigation, treatment with combined inhibitors only decreased N₂O emissions in the first cycle but not in the second cycle. Inhibitor application affected the composition of soil bacterial communities, and in particular, urease inhibitor application increased community differences across the two cycles. Moreover, using inhibitors led to a general reduction in the enrichment level of the denitrification genes narG and nosZ, and we speculate that inhibitors could also indirectly manipulate N₂O release by involving the denitrification process. Structural equation model results further displayed that the relative abundance of the nxrA and narG genes and NH₄⁺-N concentration played a vital role in the regulation of N₂O release from the alternative water-irrigated soils applied with inhibitors.

Graphical Abstract

Green, efficient, and cost-effective soil leaching technologies have emerged as an innovative strategy for remediating heavy metal-contaminated soils. In this study, we proposed NH₄HSO₄ and KHSO₄ as novel eluents for removing heavy metals from contaminated soils and investigated the effects of various factors, including leaching temperature, liquid to solid ratio (L/S), time, and molar concentration ratio, on their efficacy. We also examined the mineral contents and structural properties of the contaminated soil before and after leaching using the novel eluents via scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction spectroscopy, and Fourier transform infrared spectroscopy. The results indicated that the leaching rates of Zn, Pb, and Cd using NH₄HSO₄ and KHSO₄ (25 °C, 360 min, L/S = 20, and 0.075 mol/L) were 86.17%, 45.97%, and 79.92% and 89.12%, 46.185%, and 84.32%, respectively. Furthermore, these eluents improved the quality of the treated soil by slightly increasing its N and K contents without altering its structure. The leaching rates of Zn in the exchangeable and acid-soluble, reducible, and oxidizable forms by KHSO₄ were best fitted by the Avrami–Erofeev equation, diffusion via the product layer, and the new shrinking core model, respectively. The heavy metal proportion in the oxidizable and residual fraction increased after leaching. Based on these findings, NH₄HSO₄ and KHSO₄ show promise as effective agents for the rapid, efficient, cost effective, and sustainable remediation of heavy metal-polluted soils.