环境•农林最新文献

Ore mining and other industrial processes can release toxic elements such as zinc and cadmium into the soil, posing a potential environmental risk. Biochar produced by biomass pyrolysis is proposed to treat contaminated soils by sorption of the contaminants while boosting soil fertility, water retention, and microbial activity. Here, we propose the utilization of Carbokalk, an inexpensive byproduct (spent lime, SL) of the sugar-beet industry, as an ideal source for soil-treatment biochar. We examined the pyrolysis of SL containing up to 20% organic matter at various temperatures and in an oxidizing (air) and inert (N₂) atmosphere. Our results indicate that the pyrolysis temperatures and gas atmospheres greatly influence the physicochemical features of SL-biochar, identifying the most suitable temperature of 600 ºC for both atmospheres. SL-biochar incubation in contaminated soil has shown the potential to mitigate metal contamination in soils. However, under an oxidizing atmosphere, SL-biochar provides higher reductions in exchangeable Zn and Cd fractions. It accounts for 3% and 20%, respectively, along with increases in fractions associated with carbonate and organic matter. These findings demonstrate the effectiveness of SL-biochar in immobilizing these contaminants.

Carbon neutrality is an important goal of global energy conservation and emission reduction, and achieving the green and low-carbon technological revolution. The straw biomass in Northeast China is a potential green resource, and its pyrolysis into biochar (BC) is of great significance for carbon neutrality. This study is based on bibliometrics to conduct network co-occurrence analysis on recent BC and carbon neutrality aspects, and uses the AHP + GRA dual evaluation model for index optimization evaluation. The research direction of BC in carbon neutrality in 2023 is more focused on its carbon fixation performance for carbonaceous substances. The carbon fixation index of BC accounts for 0.314 of this layer, which exceeds 30%. GRA is used to evaluate the performance of BC, with the highest correlation between η and C₀-η (1.0), followed by pore diameter, (O + N)/C, O/C, H/C, ash, SA, pore volume, C, and pH_pzc (0.696). In the process of assisting carbon neutrality with straw BC, the focus should be on carbon sequestration performance, while also considering various factors used for preparation. The aim of this study is to optimize the carbon neutrality indicators for evaluating the resource utilization process of solid waste such as straw, in order to provide a fundamental reference for decision-makers in preparing high-value products.

Poor waste management of the products and products used in water sources becomes a problem for living organisms’ health. Using biosorbent from agro-waste materials becomes the solution for waste management and wastewater treatment. This study investigated the removal of progesterone from aqueous solutions using a biochar adsorbent derived from mixed banana and mango peels. The biosorbent shows high progesterone removal of 97.8 ± 0.02% at 700℃ preparation temperature at an optimal biosorbent concentration of 0.50 g and pH of 8. Kinetic studies showed that the adsorption followed a pseudo-second-order model. Isotherm analysis revealed that the adsorption data best fitted the Freundlich model (R² = 0.96), with a maximum adsorption capacity (q_max) of 307 mg g⁻¹, indicating multilayer adsorption with a heterogeneous surface. The Brunauer–Emmett–Teller (BET) surface area was 652 m²g⁻¹ with abundant functional groups verified by Fourier Transform Infrared Spectroscopy (FTIR). The Scanning Electron Microscopy image (SEM) indicated that the biochar is porous, contributing to its effectiveness as an adsorbent. Thermodynamics results indicate that the spontaneous nature of adsorption reveals the process. The findings proved the potential of using agricultural mixed waste-derived biochar containing various chemical and physical characteristics as an effective and sustainable adsorbent to remove endocrine disruptors. This technique addresses environmental concerns about water hormone pollution and promotes sustainable waste management practices, but the gradual decrease in adsorption efficiency highlights the importance of optimizing the biochar's chemical composition and structural reliability to maximize its performance.

Tea (Camellia sinensis) is a perennial plant and a strong fluoride (F⁻) hyperaccumulator, requiring acidic soil for optimal growth and quality. Tea plants readily absorb F⁻ from the growing medium because the soil in which tea is grown is acidic. Environmental factors (soil pH, geological sources, temperature, and rain fall) and human activities are the main contributors to F⁻ in tea. We investigated the total F⁻ content in 100 samples each of CTC and orthodox teas collected from the tea-growing regions of Northeast India. Comparatively, CTC (119.7 µg/g) tea showed higher F⁻ content than orthodox tea (76.39 µg/g), with mean fluoride concentrations below European Commission Maximum Residue Limit (400 mg/kg). The non-carcinogenic anthropogenic risk from F⁻ in tea was evaluated using Hazard Quotient (HQ) and Monte Carlo Simulation (MCS) values, which were found to be < 1 for men, women, and children, with children showing higher F⁻ intake from tea than adults. Positive Matrix Factorization (PMF) identified geogenic sources and industrial drilling as the main contributors to increased F⁻ in tea. Additionally, a geostatistical tool using Inverse Distance Weighting (IDW) and hot-spot analysis was developed to predict the spatial distribution and hot and cold spot patterns of F⁻ in tea. This study significantly enhances the understanding of F⁻ in tea from the Northeast region, indicating that contemporary Northeast Indian tea does not pose any F⁻ related health hazards, though regular monitoring for any elemental contamination remains important for tea quality and production.

Microplastics (MPs) pollution is one of the most pressing environmental problems. Rivers are important conduits for land-sea transport of materials and greatly influence the behaviour of MPs into the ocean. The Pearl River is the second largest river in China in terms of water flow and has a prosperous transport industry. Meanwhile, a large amount of MPs are transported into the South China Sea through the Pearl River. We collected water samples from the origin to the estuary of the Pearl River and studied the abundance, characteristics, ecological risks, and possible impacting factors of MPs. The results showed that the abundance of MPs in the surface water of the Pearl River Basin ranged from 0.7 to 4.5 items/L, and the distribution of abundance showed the order of: origin > estuary > downstream > midstream > upstream. MPs with sizes of 1–1000 µm were the most widely distributed, and fragments and fibers were the most prevalent MPs. The distribution of MPs showed strong spatial heterogeneity, with Polymethyl methacrylate (PMMA) dominating at the origin and upstream, polyethylene terephthalate (PET) dominating in the midstream, while polyethylene (PE) was most abundant in the downstream and estuary of the Pearl River Basin. Compared with the literature data, the concentration of MPs in the Pearl River Basin was overall low, and the pollution load index indicates that the Pearl River is at a low pollution level. However, the highly toxic PMMA could lead to significant ecological risks in the Pearl River, especially at the origin and upstream watersheds. Natural factors such as hydrological conditions, gravity, and topography can affect the migration trajectory of this MPs. Reservoirs and the concave banks of curved rivers may become new"sinks"for MPs.

Graphical Abstract

The concentration problem represents a significant challenge for membrane processes, necessitating supplementary treatment and management strategies. This study assesses the efficiency of a vacuum-assisted air gap membrane distillation/crystallization (VAGMD-C) system to addressing this issue, specifically focusing on the removal and recovery of boron, a critical raw material. Synthetic boron solutions were employed to optimize key parameters such as concentration, pH, and membrane type. Following this, real reverse osmosis (RO) concentrate was treated under optimized conditions using both commercial and custom-fabricated membranes. The experimental analyses included flux measurements, boron concentration assessments, and boron rejection rates, along with scanning electron microscope-energy dispersive spectrometry (SEM–EDS) and X-ray fluorescence (XRF) analysis of the resulting crystals. The results demonstrated that achieving up to 44.6% boron content in the crystals is feasible by utilizing the fabricated nanofiber membrane (NF) within the VAGMD-C system.

This study examines the adsorption capabilities of six types of biochars, prepared via pyrolysis of biomass materials sourced from Xinjiang, for removing pollutants from water. The results demonstrate that higher pyrolysis temperatures facilitate more complete decomposition of organic components within the feedstock, leading to increased pore size and specific surface area of the biochars. This enhancement significantly boosts the adsorption efficiency of methylene blue (MB) by the biochars. Efficient and well-structured porous biochars can be obtained at 700 °C; notably, biochars produced at 900 °C achieve MB removal efficiencies exceeding 99.5%. Furthermore, cyclic adsorption performance tests targeting MB indicate that, with the exception of corn cob biochar pyrolyzed at 900 °C, all other biochars maintain a removal rate of at least 71.4% after four cycles. The rich internal porous structure of the biochars and the presence of oxygen-containing functional groups on their surfaces enable those synthesized at 900 °C to achieve high equilibrium adsorption capacities for lead ions (Pb²⁺) in water within 30 min, averaging or surpassing 102.2 mg/g. Notably, cotton stalk biochar, which is abundant in oxygen-containing functional groups, exhibits a maximum equilibrium adsorption capacity for Pb²⁺ of up to 196.0 mg/g. Importantly, during the four cycles of reuse, both cotton stalk biochar and bamboo biochar pyrolyzed at 900 °C display relatively stable adsorption characteristics for Pb²⁺. Kinetic model analysis reveals that the adsorption processes of MB and Pb²⁺ by these biochars conform to both pseudo-first-order and pseudo-second-order kinetic models. These findings provide valuable guidance for the application of biochars in water treatment fields.

This study investigated the contents, spatial distribution, and ecological and health risks of nine metals in 19 coastal sediments from Sharm El Luli area, Red Sea. Metals followed a decreasing pattern: Fe > Ba > V > Cr > Zn > Pb > Cu > Ni > Co. Pb, Cr, and V exceeding the Canadian soil quality guidelines and earth crust backgrounds. Levels of Pb, Cr, Ni, and Zn in Sharm El Luli’s sediments have surpassed their respective Effect Range Median (ERM) values, suggesting potential adverse effects on local biota. Factor analysis results showed significant loads of Ba, Co, V, pH, and TOM% (F1: 21.3%), Cu, Cr, Sand%, and Mud% (F2: 18.6%), and Pb, Ni, Zn, Fe, and Gravel% (F3: 18%). Contamination factor values indicated low (Ba and Fe), moderate (Co, Cu, Cr, Ni, and V), considerable (Pb), and high (Zn) contamination. Geo-accumulation index of all metals indicated extremely contaminated sediments (I_geo > 5). The Potential ecological risk index of metals examined showed low risk (PERI < 150). Mean effects range median quotient (MERMQ) value (1.08) showed medium–high priority risk (0.51 < MERMQ ≤ 1.5), and Toxic risk index showed moderate toxicity risk. Non-carcinogenic risk index (HI) values indicated no chronic risk (HI < 1), and total carcinogenic risk (TCR) values were below the safe limit (1 × 10⁻⁴). The distribution of natural radioactive elements in sediments was also assessed. Mean ⁴⁰ K, ²²⁶Ra, and ²³²Th activity of sediments were 23.32, 24.57, and 241.83 Bq/kg, respectively, being lower than the recommended global limits. The heavy minerals detected are pyrite, ilmenite, and beryl. The study underscores the urgent need for comprehensive management strategies to mitigate environmental hazards from heavy metal pollution in coastal sediments, requiring ongoing scientific investigation and cooperation, which will play a crucial role in protecting the Red Sea's marine ecosystem.