Water, Air, & Soil Pollution最新文献

The addition of litter may induce greenhouse gas (GHG) emissions to varying degrees depending on the mineral soil and the organic horizon. An assessment was made to deduce the impact of different litter addition rates on soil GHG emissions, physicochemical properties, and the abundance of functional genes involved in carbon and nitrogen cycles in both the organic horizon and mineral soil. Compared with soil without litter amendment, cumulative CO₂ emissions increased by 6.85% to 11.87% in organic soil and by 16.66% to 54.43% in mineral soil. However, there was no significant difference in cumulative N₂O emissions in the organic soil layers. Cumulative N₂O emissions increased by 26.03% to 172.63% in the mineral soil. Soil dissolved organic carbon (DOC) increased by 21.63% to 40.87%, while NO₃⁻ decreased by 22.03% to 57.24% with litter input. Furthermore, soil pH and dissolved organic nitrogen decreased by 1.34% to 3.19% and 13.28% to 21.51%, respectively, whereas NH₄⁺ increased by 40.28% to 81.04% in the mineral soil compared with with soil without litter addition. Following litter amendments, changes in N₂O emissions were mainly driven by variations in soil physicochemical properties in the mineral soil, whereas in the organic horizon soil, they were influenced by the amoA2 gene. In the organic horizon soil, both labile (xylA, a xylose isomerase-related gene) and recalcitrant (chiA, an endochitinase-related gene) carbon degradation genes, along with DOC, played a dominant role in soil CO₂ emissions. The recalcitrant carbon degradation related gene (lig, a lignin degradation related gene), along with DOC and pH, contributed to CO₂ emissions in the mineral soil. This study enhances our understanding of how GHG emissions respond to litter accumulation in the organic horizon and mineral soil and highlights the importance of litter management in mitigating GHG emissions in agricultural environments.

The transfer of arsenic (As) from contaminated soil to the human body through rice represents a health catastrophe in the Bengal Delta Plain (BDP), emphasizing the need for a deeper understanding of the indispensable factors influencing the mobility and retention of As in the paddy soils of BDP. This study examined the effects of temperature and rice root-secreted low-molecular-weight organic acids (LMWOAs), at field-relevant levels, on As adsorption and desorption, while evaluating the influence of silicon (Si) on As desorption in BDP paddy soil, using thermodynamic analysis and equilibrium modeling. Arsenic adsorption and desorption experiments were conducted at two temperatures (20 and 35 °C) with and without LMWOAs, and the effect of Si (0–100 mg L⁻¹) on As desorption was evaluated. The adsorption data were analyzed using a newly developed R package, “AdIsMF” for linear and nonlinear Freundlich and Langmuir isotherm models. Results revealed a considerable adsorption capacity (q_max: 698–813 mg kg⁻¹) driven by endothermic, entropy-driven adsorption processes. The q_max and adsorption affinity (K_l) increased at higher temperatures to 12.4–13.3% and 19.5–26.6%, respectively. LMWOAs had minimal impact on adsorption isotherm, slightly reducing K_l (1.14 to 0.98 L mg⁻¹) alone, but significantly impacting the energetics of As adsorption. The linear Langmuir model outperformed others in model selection criteria and accuracy measures, indicating monolayer adsorption on homogeneous surfaces. The adsorption mechanism was inferred to be predominantly chemisorption, supported by physisorption. Desorption studies revealed irreversible As binding to soil, with greater desorption at lower temperatures. Silicon concentrations above 1 mg L⁻¹ significantly enhanced As mobility, with cumulative desorption reaching 31.5% under 100 mg L⁻¹ Si. These findings underscore the importance of soil temperature, i.e. rice cultivation season, on As availability, and dose-optimization of Si amendments to mitigate As risks in paddy systems.

The enrichment of metal ions on the surface of clay particles significantly leads to the loosening of the particle surface structure, thereby weakening the macroscopic engineering properties of the clay. In this study, sodium ions (Na⁺) and potassium ions (K⁺) as monovalent metal ions, along with lead ions (Pb²⁺) and zinc ions (Zn²⁺) as divalent metal ions, were selected as metal ion contaminants. The focus was to investigate their effects on the microstructural morphology, macroscopic engineering properties, and electrical properties of the clays. The aim of the study is to clarify the relationship between the valence state and concentration of these four types of metal ions and the engineering properties of clay, and to predict the engineering properties of metal-ion-contaminated clay using resistivity parameters. The results indicate that the incorporation of metal ions reduces the average particle size, transforming the soil structure from flaky to a honeycomb form. Under the same loading conditions, metal-ion-contaminated clay exhibits a lower void ratio. As the concentration of metal ions increases, pore volume decreases, thereby enhancing soil compressibility. Alkali metal ions primarily influence the soil structure through a dispersive effect, while heavy metal ions exert a cohesive effect. Monovalent alkali metal-ion-contaminated clay demonstrates larger compression coefficients across all load levels, whereas heavy metal-contaminated soils exhibit higher compression coefficients under low loads. Furthermore, the shear strength and cohesion of metal-ion-contaminated clay are lower than those of field-state clay. At lower concentrations, the internal friction angle may exceed that of field-state clay; however, as the concentration of metal ions increases, the shear strength, internal friction angle, and cohesion significantly decrease. The presence of metal ions also reduces soil resistivity, which declines at a diminishing rate with increasing concentration. At lower ion concentrations, monovalent alkali metal ions have a slightly stronger effect on reducing resistivity compared to divalent heavy metal ions. Resistivity parameters effectively reflect the compressibility and shear characteristics of metal-ion-contaminated clay, revealing a negative linear correlation between resistivity and compression ratio under uniaxial loading, while a positive linear correlation exists with shear strength, internal friction angle, and cohesion. These insights provide a basis for the rapid evaluation of engineering characteristics in metal-ion-contaminated clay.

The novel adsorbent of KMnO₄-modified spent coffee grounds (KMnO₄-SCGS) was successfully synthesized for the adsorption of Pb(II). Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and other characterization measurements were employed to evaluate the physical and chemical properties of KMnO₄-SCGS. The results demonstrated that the adsorption behavior of Pb(II) was best fitted by the pseudo-second-order, Ritchie, and Langmuir isothermal models, indicating that the surface of KMnO₄-SCGS was composed of homogeneous adsorption. The surface complexes with manganese oxide (MnO_x) and oxygen-containing functional groups, along with electrostatic interaction, physical adsorption, and ion exchange, played significant roles in the adsorption of Pb(II). The Langmuir maximum adsorption capacity for Pb(II) was 203.8 mg/g for KMnO₄-SCGS, which was approximately 11.73 times higher than that of SCGS, and it remained over 80% after five cycles. Finally, the Box-Behnken design was utilized to optimize the results. Therefore, the modification of spent coffee grounds by KMnO₄ is a feasible approach for the adsorption of Pb(II).

Graphic Abstract

A simple-to-operate, environmentally friendly method has been developed for novel Ag sphere synthesis in NADES media to achieve spherical form and for green synthesis that was modified with MoS₂ nanoparticles. Ag@MoS₂ was designed as an adsorbent for a rapid and economical dispersive micro solid phase extraction approach at trace levels. The Analytical parameters pH (5.0), sorbent mass (10 mg), extraction time (2.5 min), eluent volume (5 mL), eluent type (acetonitrile), and sample volume (10 mL) were optimized. The detection limit was found to be 0.6 μg L^–1 and the technique’s linearity ranged from 2.1 to 250 μg L^–1. The suggested approach has several benefits, including selectivity, precision, and rapidity. It is used practically to identify ATZ in lake water, fish farming water, tap water, allspice and rosehip. The ATZ recovery was sufficient, averaging between 91 and 107%. The method had an overall score of 0.57 on the AGREE scale.

Adsorption is a pivotal process in environmental cleanup and wastewater treatment due to its simplicity, cost-effectiveness, and sustainability. The quantification of adsorption is often expressed through Adsorption Isotherms, which model the substance adsorbed by a substrate at equilibrium. Understanding single, multi-component, and competitive adsorption isotherms is crucial for designing effective water treatment systems. Experimental data modeling plays a significant role in predicting adsorption mechanisms. This review explores isotherm models'foundational knowledge and practical applications, offering insights into their conceptual framework and utility. It covers single and multi-component contexts, extensively discussing various isotherm models and their parameters. The debate over linearization in adsorption equations is addressed, highlighting factors influencing parameter determination such as linearization method, experimental error, and data range. The paper elucidates techniques like linear and nonlinear regression analysis and error functions for optimal adsorption data analysis, providing a comprehensive understanding of the subject.

Graphical Abstract

Activated coke waste (ACW), a byproduct of industrial desulfurization and denitrification, consists of fine particles (< 1 mm) with a porous structure, high specific surface area, and pH ~ 5, rendering it a candidate for saline-alkali soil remediation. However, its inherent excess salts and contaminants restrict direct agricultural application. In this study, ACW was treated with a dilute nitric acid solution to remove excess salts and contaminants, yielding the soaked activated coke waste (SACW) sample. The research systematically examined the adsorption properties and mechanisms of SACW for salt ion removal by solution experiment. Additionally, soil cultivation experiments were conducted to evaluate its potential in improving plant growth within saline-alkali soils. Compared to raw ACW, SACW exhibited reduced pH and electrical conductivity (EC), elevated oxygen-to-carbon (O/C) ratio, and expanded pore volume. SACW displayed ion adsorption selectivity in the order of SO₄²⁻ > Na⁺ > Cl⁻. Isothermal adsorption analysis revealed that Na⁺ and Cl⁻ adsorption aligned with the Langmuir model, whereas SO₄²⁻ adsorption adhered to the Freundlich model. Application of SACW (≥ 10 g kg⁻¹) effectively improved saline-alkali soil properties by lowering pH and salinity, enhancing soil aggregate stability, and promoting nutrient utilization efficiency. Notably, SACW-treated soils supported maize plants with significantly increased height and biomass (13.94% and 159.28% higher, respectively; P ≤ 0.05) compared to untreated controls. These benefits stemmed from improved nutrient availability and reduced salt stress-induced plasma membrane damage. These findings validate SACW as a sustainable, functional amendment for reclaiming saline-alkali ecosystems and boosting crop productivity.

Understanding soil carbon dynamics in climate-sensitive alpine ecosystems is critical for addressing global warming challenges. This study systematically investigated CO₂ flux patterns and drivers in cropland and grassland ecosystems (2000–2020) across China's eastern Qilian Mountains through integrated field monitoring, remote sensing and modeling. Results revealed rapid vertical CO₂ flux intensification at − 10 to − 20 cm depths, with cropland and grassland soils exhibiting 623–1,252 ppm and 690–1,133 ppm respectively, which is 4–5 times higher than atmospheric levels, driven by microbial activity and pore structure transitions. Principal Component Analysis identified soil nutrient interactions explaining 69.6% of soil biogeochemical variance, where subsequent altitude-nutrient interaction analysis revealed elevation-driven soil organic carbon (SOC, R² = 0.7253, p < 0.05) and total nitrogen (TN, R² = 0.6841, p < 0.01) correlations in cropland and total phosphorus (TP, R² = 0.4278, p < 0.01) correlation in grassland. Over two decades, 99.53% of the study area exhibited rising net primary productivity (NPP), with 72.62% showing extremely significant increases, synergistically enhanced by climate drivers (90.9% of the area) and human activities (99.5% of the area). Land-use change significantly influenced carbon storage in last two decades with an overall decrease in 0.100 Mt of C, which suggested increasing pressure on the ecosystem from human activities and climate changes. This study provides a reference for carbon cycle process and ecological protection in high-altitude regions, highlighting the need for further innovation in policies that integrate altitude-specific nutrient management with adaptive land-use planning, with methodological frameworks transferable to global mountain systems facing similar climate and anthropogenic challenges.

This study investigates the impact of domestic sewage wastewater irrigation on the cultivation of cassava (Manihot esculenta Crantz) from selected agrofields of Palakkad, Kerala with a comparison of well-water-irrigated M. esculenta from the same area. For this, the physicochemical parameters of respective water and soil samples were analysed. Further, to understand the post-harvest crop quality which includes the peeled tuber, peel, leaf and stem proximate composition, and mineral contents including heavy metal composition and in vitro antioxidant potential. The results of the physicochemical parameters of both domestic sewage wastewater and well-water irrigated samples (both water and soil) were observed within the permissible limits according to the WHO/FAO suggested pattern. Interestingly, heavy metals such as Zn, Cd, Cr, Cu, and Ni were within the admissible limit in respective samples from both fields. In general, when compared with well-water irrigated cassava crop samples, the antioxidant potential was significantly higher (p < 0.05) in sewage wastewater irrigated cassava samples. The present study demonstrated that domestic sewage water was found to have promising physicochemical properties that allow for safe use for irrigation as liquid organic fertilizers and the cassava crop residues from such agrofields could also be exploited as potential animal feed.

Graphical Abstract

The issue of plastic waste has increased substantially due to the extensive employment of man-made polymers across multiple industries. These plastics derived from fossil fuels, such as polyethylene, polystyrene, and polypropylene, are difficult for nature to break down independently. Fortuitously, some microbes have developed the potential through evolutionary adaptation to break down these long-lasting synthetic compounds. Certain microorganisms have evolved the ability to decompose these durable polymers. Some beneficial soil bacteria called plant growth-promoting bacteria have shown promise in both supporting plant growth and development and degrading plastics. Various species of Bacillus and Pseudomonas contain enzymes enabling them to metabolize polyethylene. Rhodococcus species possess similar complimentary enzyme complexes suited for polypropylene degradation. These microbes employ hydrolytic and oxidative enzymes to initiate the plastic breakdown process. Additional soil organisms then further facilitate the mineralization of the fragmented polymers. The nitrogen-fixing Rhizobium can attack polystyrene. The multi-step mechanism often starts with surface oxidation catalyzed by bacterial enzymes. Multiple studies have isolated strains like Brevibacillus borstelensis and photosynthetic Rhodopseudomonas able to consume polyethylene. Meanwhile, certain Streptomyces also have polypropylene depolymerization potential. Overall, applying plastic-eating microbes offers hope for plastic waste management while lessening environmental harm and propelling the shift to a circular economy.

Graphical Abstract