环境•农林最新文献

Global higher consumption of water resources, accompanied by increased wastewater discharge, has led to widespread water contamination and a decline in Earth's freshwater reserves. Hence, cost-effective, efficient, and environmentally friendly treatment methods are needed to obtain contaminant-free water for reuse. Chitosan, an amino polysaccharide derived from renewable sources, has recently gained prominence as a crucial component in the synthesis of hydrogels with potential and practical applications in wastewater treatment. The biodegradable and biocompatible nature, along with the chemical multifunctionality, of chitosan make it an ideal substrate for producing nature-friendly hydrogel adsorbents, provided their cons, such as mechanical weakness, easy deterioration in aqueous media, and limited regeneration capacity, are overcome. Chitosan-based hydrogels are formed by various chemical and physical modifications on chitosan, including crosslinking, grafting, blending, and interpenetration with other polymers. This review highlights recent advancements in chitosan-based hydrogels for wastewater treatment, focusing on improved adsorption capabilities, multifunctional hydrogels, and enhanced regeneration potential, and identifies areas for further research in this field. The article presents the background leading to the development of new, advanced chitosan hydrogel adsorbents, based on the fundamentals of chitosan hydrogel synthesis. It provides a comprehensive account of the mechanisms of heavy metal and dye adsorption by chitosan hydrogels. It examines the potential of advanced chitosan-based hydrogels to tackle the global pollution problem by assessing their capacities, efficiencies, regenerative abilities, as well as their weaknesses for selected pollutant removal from contaminated waters.

Plant growth is significantly impacted by the concentration of nutrients in the soil. Accurate and real-time measurement of nitrates and nitrites levels remains a significant challenge. Existing laboratory-based methods are expensive, time-consuming, and labor-intensive, highlighting the need for a rapid, on-site solution. This study proposes a rapid method for measuring nitrates and nitrite levels in water samples collected from tile drainage. We utilized Hach Nitrate and Nitrite test strips for image dataset collection as these test strips change color based on the concentration of nitrate and nitrite in the water samples. A purpose-built black box, equipped with an internal lighting arrangement for imaging test strips, was designed to collect images of the test strips. Unlike many existing smartphone-based colorimetric approaches, which are sensitive to ambient lighting variations and often rely on external calibration or offline analysis, the proposed system integrates a controlled illumination environment with real-time edge computation for robust on-site detection of nitrate and nitrite. An Nvidia Orin Nano module, connected with an IMX219 camera sensor, was used to capture images of the test strips. Image preprocessing was performed, followed by the implementation of a VGG16-based network for feature extraction. A dataset of approximately 3128 images spanning multiple nitrate and nitrite concentration levels was collected under controlled imaging conditions. Multiple machine learning models including logistic regression (LR), support vector machines (SVM), k-nearest neighbors (KNN), naïve Bayes (NB), and random forest (RF) were evaluated for classification. The nitrate detection using KNN achieved an accuracy of 99.96% training, 99.92% testing, and 99.79% cross-validation. For nitrite detection, the SVM model achieved accuracy of 99.02%, 98.04%, and 98.07% for training, testing, and cross-validation, respectively, demonstrating both systems' high reliability and practical applicability for real-time monitoring. The total system cost is approximately USD 300, highlighting the affordability and practicality of the proposed solution for on-site water quality monitoring. This technology can enable farmers, water quality researchers, and agronomists to efficiently monitor the levels of nitrates and nitrites in tile drainage samples, enabling data-driven decisions to maximize crop yields.

The release of phosphorus from sediments is a critical driver of water eutrophication, yet its dynamics and impact on surface water quality of different water layers in river systems remain understudied. As an important basin ecosystem in Northern China, the Liaohe River undertakes key functions such as regional water resource supply, agricultural irrigation, and maintenance of ecological balance, and its water quality directly affects the production and life of residents in the basin and ecological security. This study investigated the release characteristics and influencing factors of different phosphorus forms (total phosphorus, TP; phosphate, PO₄³⁻) in the Liaohe River, a typical agricultural area of Northern China, using static simulation and statistical analyses. Results revealed significant spatial and temporal variations in phosphorus release: TP exhibited rapid early release followed by stabilization, with release rates of 0.0097–0.0150 mg/(m²·d) (upstream), 0.0112–0.0223 mg/(m²·d) (downstream), and the highest 0.0316–0.0342 mg/(m²·d) (midstream), showing a "high-middle and low-ends" spatial pattern. Environmental factors—temperature (25–30 °C), pH (7–9), light, and hydrodynamic disturbances—synergistically enhanced phosphorus release, with hydrodynamic forces exerting the most pronounced effect. Correlation analysis and RDA analysis confirmed that PO₄³⁻ in pore water correlated strongly with overlying water nutrient levels (r = 0.60, p < 0.05), indicating its pivotal role in eutrophication. PO₄³⁻ in pore water can serve as a key indicator for water quality monitoring. This study underscores the necessity of addressing internal phosphorus loading alongside external controls to mitigate eutrophication in riverine ecosystems. The management approach must shift from a total phosphorus-centered method to targeted phosphate ion control, while integrating sediment remediation and hydrological regulation.

This study investigates the valorization of hydrochar generated from the hydrothermal liquefaction of butia endocarp, an agro-industrial residue, as a precursor for activated carbon (AC) applied to the removal of the emerging contaminants paracetamol and 2,4-D from aqueous solutions. The hydrochar was activated with H₃PO₄ and subjected to pyrolysis, resulting in an AC with a predominantly mesoporous structure, amorphous character, high surface area (S_BET = 1045 m² g⁻¹), and a total pore volume of 0.139 cm³ g⁻¹. Kinetic studies indicated rapid adsorption, with the General Order model providing the best fit, revealing distinct adsorption mechanisms for the contaminants. Paracetamol exhibited more complex kinetics (n ≈ 4.8), whereas 2,4-D showed behavior close to first-order kinetics (n ≈ 1). Equilibrium data were well described by the Sips isotherm, resulting in maximum adsorption capacities of 99.5 mg g⁻¹ for paracetamol and 116.0 mg g⁻¹ for 2,4-D under optimized conditions (pH 2 for paracetamol, natural pH for 2,4-D, adsorbent dosage of 1.5 g L⁻¹, initial concentration of 200 mg L⁻¹, contact time of 3 h, and 55 °C). Thermodynamic analysis demonstrated that adsorption is spontaneous (ΔG° < 0) and endothermic (ΔH° > 0), being favored by increased entropy (ΔS° > 0). The adsorbent exhibited high removal efficiency (> 90%) over a range of concentrations, good reusability, and satisfactory performance in a multicomponent effluent. These results indicate that AC derived from agro-industrial residues represents a sustainable and effective alternative for treating effluents containing emerging contaminants.

Global soil tellurium (Te) contamination requires effective and economical solutions for food safety. This research presents results from the pot trial aimed at investigating the interactive impacts of nano-biochar (NB) (NB1: 0, NB2: 1 and NB3: 2%), foliar nano-silicon (NS) (NS1: 0, NS2: 0.25 and NS3: 0.50 mM) and WM (water management) (WM1: 70% WHC and WM2: continually flooding) on tellurium impacts on microbial communities and wheat plants in Te-polluted soil (0.89 mg/kg total Te) and linked health risks. During milking stage, NB3WM2 interaction significantly affected SPAD, resulting in an 8.39% increase relative to NB1WM1. The assessed yield characteristics were markedly influenced by main impacts of WM, NB and NS, with NB2 and NB3, NS2 and NS3, and WM2 exhibiting elevated values compared to NB1, NS1 and WM1. Comparable outcomes were noted for bioavailable Te levels; nevertheless, NS exhibited no significant impact. The NB3NS3WM2 interaction markedly elevated SOD by 89.87%, whereas NB2NS3WM2 interaction demonstrated most substantial decreases in MDA and H₂O₂ (58.01%) and (30.14%) compared to NB1NS1WM1. NB2NS3WM2 interaction led to a 96% decrease in grain Te level relative to NB1NS1WM1 and improved bacterial Chao1, ACE and Shannon metrics, and fungal Chao1 and ACE metrics. Ultimately, NB1BS1WM1 interaction exhibited maximum health risk index of 0.170 and daily intake of 1.70E-03, whereas NB2NS3WM2 interaction demonstrated lowest daily intake of 9.10E-07 and health risk index of 0.009. Our findings indicate that utilization of NB2NS3WM2 can markedly reduce Te concentration and absorption in wheat, alleviate health risks, and improve soil microbial ecosystem.

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The incineration process is characteristic of reduction, resource utilization, and detoxification. However, the presence of heavy metals is one of the limiting factors for its incineration and utilization. This study used the municipal sludge (MS) from a sewage treatment plant in Tianjin as an example and employed FactSage thermodynamic simulation software to analyze the effects of sulfur (S), chlorine (Cl) and its own mineral elements on the migration and transformation of heavy metals (lead [Pb], cadmium [Cd], arsenic [As], and copper [Cu]) under different incineration temperatures (200 °C–1400 °C). Thermodynamic calculations revealed a competitive relationship between heavy metal sulfates and chlorides over the temperature range. When both S and Cl were present, Cl reduced the temperature range of PbSO₄(s) by converting it to PbCl₂(g) at 600 °C–820 °C, thus promoting Pb transfer to the flue gas. CdCl₂(s) could displace CdSO₄(s) at temperatures below 280 °C. Above 780 °C, Cd volatilization became highly temperature-dependent, and Cd was emitted into flue gas in monomeric form. S and Cl had minimal effects on the migration and transformation of As, which was predominantly immobilized by the presence of Al₂O₃. Above 600 °C, Cl promoted the volatilization of Cu as CuCl(g). These results can help predict the migration and transformation behavior of heavy metals during sludge incineration and provide theoretical guidance for emission control and utilization of heavy metals.

This study investigates the sorption mechanisms and influencing factors of fluoroquinolone veterinary antibiotics, particularly enrofloxacin (ENR), in loess soil amended with organic fertilizers. Employing a batch equilibrium test method, the research scrutinizes the impacts of sorption kinetics, thermodynamics, coexisting ionic strengths and types, pH levels, and diverse ratios of chicken manure on ENR sorption onto loess, both pre and post introduction of chicken manure as the target pollutant. The findings reveal a noteworthy extension in the sorption equilibrium time of ENR on loess, escalating from 60 to 120 min following the application of chicken manure fertilizer (CMF), resulting in a heightened sorption rate of ENR on loess through the involvement of multiple sorption mechanisms. Under laboratory conditions at 25℃and pH = 7, the application of CMF triggers a substantial rise in soil organic matter content, leading to a significant augmentation in the linear sorption equilibrium constant Kd (L/Kg) from 66–84 L/kg to 922–1264 L/kg, thereby bolstering the sorption affinity of loess for ENR. In loess, elevated concentrations of alkali metal ions (K⁺, Ca²⁺, and Mg²⁺) suppress ENR sorption through complexation or cation bridging interactions. In contrast, NH₄⁺ ion hydrolysis promotes ENR sorption by acidifying the solution and facilitating cation exchange with the soil surface. ENR manifests reduced sorption quantities with escalating pH levels, with elevated quantities and swifter rates observed under acidic conditions. Moreover, a higher percentage of CMF application amplifies the sorption effect. Following CMF application, ENR sorption tendencies exhibit stability, with accelerated sorption rates influenced by coexisting ions, pH levels, and CMF proportions. This study highlights the key role of increased organic matter content following chemical fertilizer application in enhancing the adsorption capacity of loess soils for environmental nutrients, prolonging the equilibrium time, strengthening their retention capacity in soil, and reducing the mobility risk of environmental nutrients in the soil. These findings will provide important references for assessing the migration and transformation risks of organic pollutants in loess soils after organic fertilizer application, thereby enriching environmental assessment practices in this field.