Search Results (921)

Abstract: The co-contamination of nitrate nitrogen (NO₃⁻-N) and tetracycline (TC) in aquaculture water has caused serious environmental and health problems. Bioremediation is a promising approach for the removal of NO₃⁻-N and TC. However, free bacteria are sensitive to environmental variation, limiting its application. In this study, a bacterial strain with high NO₃⁻-N and TC degradation ability, Bacillus cereus W2, was isolated and immobilized on wheat straw biochar by an adsorption method. The effect of immobilization conditions, including biochar dosage, inoculum amount, and immobilization time on NO₃⁻-N and TC removal was explored. The degradation abilities of the biochar-immobilized Bacillus cereus W2 under different nitrate and TC concentrations was investigated. Results showed that the prepared biochar had abundant functional groups such as -COOH, -OH, -C=C-OH, etc., which have good affinity for microbial cell membranes and are conducive to the adhesion and proliferation of microbial cells. The highest NO₃⁻-N and TC removal efficiencies of 99.50% and 78.60% after 24 h were obtained under a biochar dosage of 4 mg·mL⁻¹, microbe inoculation amount of 40%, and immobilization time of 24 h. The immobilized Bacillus cereus W2 performed better NO₃⁻-N and TC removal than the free cells under different initial NO₃⁻-N and TC concentrations. The enhanced removal of NO₃⁻-N by the biochar-immobilized Bacillus cereus W2 may be attributed to the promoted expression level of functional genes involved in denitrification (nirS, norB, and nosZ). The biochar-immobilized Bacillus cereus W2 demonstrates potential for treating various nitrate-antibiotic co-contaminated wastewaters, including those from livestock farming, aquaculture systems, and pharmaceutical industries. Full article

The unreasonable application of nitrogen (N) fertilizer leads to high nutrient losses and severe potential of agricultural non-point source contamination, which threatens water quality in the upper Yellow River Basin. Therefore, the aim of this study is to explore the effects of N application rates and various control measures on rice yield and N leaching in paddy fields in the Yellow River irrigation area. Four treatments were employed in this study, CK (no N fertilizer application, 0 kg N∙ha⁻¹), CRU (controlled-release urea application, 180 kg N∙ha⁻¹), OPT (optimal N fertilizer application, 210 kg N∙ha⁻¹), and FP (N fertilizer application based on farmer experience, 240 kg N∙ha⁻¹), to examine paddy yield, N use efficiency (NUE), N concentrations in leaching water at various soil depths, and N contents along the 0–100 cm depth of the soil profile. The results indicated that the amount of TN leached was 25.14–48.04 kg∙ha⁻¹ after different N applications, and the TN leaching coefficients of FP, OPT, and CRU were 10.88%, 11.27%, and 7.07%. Compared to FP and OPT, the CRU significantly reduced the concentrations of TN, ammonium N (NH₄⁺-N), and nitrate N (NO₃⁻-N) in the surface and soil water, with average TN leaching decreasing by 31.55% and 27.35% in the years 2022 and 2023, respectively. NO₃⁻-N was identified as the primary form of N leached from the paddy fields. Compared to FP and OPT treatments, the CRU treatment increased the average paddy yield by 19.99–20.66% and improved the average NUE by 19.04–16.38%. This study revealed that the application of high amounts of N positively affected soil N leaching, and controlled-release urea demonstrates superior efficacy compared to conventional fertilization. The application of controlled-release urea at a rate of 180 kg N∙ha⁻¹ not only ensures a good paddy yield but also reduce N losses, which should be recommended to local farmers. Full article

Riverbank filtration (RBF) technology has been applied and investigated worldwide for water supplies due to its sustainable water quantity guarantee and reliable quality improvement. In this work, the development history, application status, research progress, and technical overview of RBF are reviewed and summarized. RBF usually uses rivers, lakes, and groundwater as raw water, with a few cases using seawater. Nitrogen removal in RBF systems primarily occurs through key geochemical processes such as adsorption, denitrification, organic nitrogen mineralization, and dissimilatory nitrate reduction to ammonium (DNRA). For the attenuation of emerging contaminants in groundwater environments, key processes such as filtration, adsorption, and biotransformation play a crucial role, and microorganisms are essential. Based on a discussion of the advantages and disadvantages, we proposed the research prospects of RBF. To further enhance the water-supply safety and security with RBF, the mechanisms of surface water and groundwater interaction, pollutant removal, and blockage; the impact of capturing surface water on the stability of river ecosystems; and the coupling and synergistic effect of RBF with other water treatment technologies should be deeply investigated. Full article

Solvents are particularly hazardous among the mixture of pollutants found in the air, as their low vapor pressure allows them to reach the atmosphere, causing damage to ecosystems, and producing secondary deleterious effects on living organisms through a wide variety of possible reactions. In response, innovative, sustainable, and ecological methods are being developed to recover solvents from industrial wastewater, which is typically contaminated with other organic compounds. This study describes the procedure for recovering acetone from a residue from the pharmaceutical industry. This compound contains a high amount of solid organic compounds, which are generated during the manufacture of medicines. The treatment consisted of performing a simple solar distillation using a single-slope glass solar still, which separated the acetone from the mother solution. Under ideal circumstances, the use of solar radiation allowed an efficiency rate of 80% using solar concentration by means of mirrors to increase the temperature and 85% without the use of mirrors in the production of distilled acetone, which was characterized to evaluate its quality using instrumental analytical techniques: NMR, IR, and GC. The results obtained indicate that the acetone recovered by this procedure has a good quality of 84%; however, due to this percentage obtained, its reuse is limited for certain applications where a high degree of purity is required, such as its reuse for pharmaceutical use; for this reason, it was proposed to use said compound to eliminate the organic impurities contained in the catalyst waste granules used in a Mexican oil refinery. The resulting material was examined by SEM and EDS, revealing a high initial carbon content that decreased by 29% after treatment. Likewise, as an additional study, a study was carried out to evaluate the characteristics of the residues obtained at the end of the distillation where rubidium, silicon, carbon, nitrogen, oxygen, and chlorine contents were observed. Full article

Although the cultivation of food crops in farmland heavily contaminated by heavy metals is prohibited in China, vegetables can still be planted on a small-scale due to their short growth cycles and flexible sale models, posing a significant threat to local consumers. In this study, a pot culture experiment was conducted to investigate the feasibility of safe production through the in-situ stabilization of heavy metals in heavily contaminated soil. The remediation efficiency of wheat straw biochar and N-doped biochar, the growth of spinach, the heavy metal accumulation in spinach, and potential health risks were also explored. The results indicated that both biochar and N-doped biochar significantly affected the soil pH, cation exchange capacity, organic matter, available phosphorus, available potassium, alkaline nitrogen content, and spinach biomass, but the trends were variable. Additionally, the diethylenetriaminepentaacetic-extractable Pb, Cd, Cu, Zn, and Ni concentrations decreased 9.23%, 7.54%, 5.95, 7.44%, and 16.33% with biochar, and 10.46%, 12.91%, 21.98%, 12.62%, and 12.24% with N-doped biochar, respectively. Furthermore, N-doped biochar significantly reduced the accumulation of Pb, Cd, and Ni in spinach by 35.50%, 33.25%, and 30.31%, respectively. Health risk assessment revealed that the non-carcinogenic risk index for adults and children decreased from 17.0 and 54.8 to 16.3 and 52.5 with biochar and 11.8 and 38.2 with N-doped biochar, respectively, but remained significantly higher than the acceptable range (1.0). The carcinogenic risk assessment revealed that the risk posed by Cd in spinach exceeded the acceptable value (10⁻⁴) for both adults and children across all treatments. These results may imply that biochar and N-doped biochar cannot achieve the safe production of vegetables in soil heavily contaminated by heavy metals through in-situ stabilization. Full article

Tramadol is a widely used pain medication detected in wastewater treatment plants, prompting concerns about its impact on the environment and the effectiveness of wastewater treatment. Nitrogen-doped carbon quantum dots (NCQDs) can be used to remove pollutants from the contaminated water sources. However, NCQDs can hardly be recovered after applications, leading to high regeneration costs. Thus, this study aims to explore the use of magnetite nitrogen-doped carbon quantum dots (magnetite NCQDs) fabricated from empty fruit bunches (EFBs) to remove tramadol from wastewater treatment. Various analytical methods were conducted to characterize the magnetite NCQDs. Magnetite NCQDs showed excellent separation and aggregate-free properties. This study investigated the effect of the initial concentration of tramadol, the dosage of magnetite NCQD adsorbent, and the contact time while keeping other parameters constant. Tramadol was efficiently adsorbed within 40 min with an adsorption efficiency of over 85.9% and further photodegraded by 4.5% after being exposed to UV light after undergoing photocatalysis for 50 min. Magnetite NCQDs exhibited outstanding properties in removing tramadol after undergoing five cycles. This research provides a promising approach for developing a highly efficient adsorbent for treating tramadol-contaminated wastewater. Full article

Microplastics (MPs) have emerged as a significant environmental threat, infiltrating livestock systems. This study presents the first in vitro investigation of the effects of low-density polyethylene (LDPE) MP contamination on rumen fermentation dynamics and feed utilization in a simulated ruminal digestive system. Concentrate feed was incubated in buffered rumen fluid collected from lambs, supplemented with LDPE MPs at concentrations of 3.3 g/L and 6.6 g/L and compared to the concentrate incubated in the buffered rumen fluid without MP contamination. The results demonstrate that both levels of LDPE MPs significantly altered rumen fermentation dynamics by reducing asymptotic gas production by 11% and 15% and increasing the constant rate of gas production by 16% and 19% at low and high addition levels, respectively, compared to the control. However, the early-stage fermentation dynamics remained unaffected. Furthermore, both levels of LDPE MPs reduced rumen protozoal populations (20% and 23%) and ammonia-nitrogen levels by 11% at both of addition levels. Despite these disruptions, rumen pH remained unaffected. Increasing the addition level of LDPE from 3.3 to 6.6 g/L did not exacerbate the disruptions. The results of this study highlight the potential risks posed by LDPE MPs in ruminal nutrition. Further in vivo investigations are essential to validate these findings and assess their impact on animal performance. Full article

One of the most important and essential components of sustainable agricultural production is biostimulants, which are emerging as a notable alternative of chemical-based products to mitigate soil contamination and environmental hazards. The most important modes of action of bacterial plant biostimulants on different plants are increasing disease resistance; activation of genes; production of chelating agents and organic acids; boosting quality through metabolome modulation; affecting the biosynthesis of phytochemicals; coordinating the activity of antioxidants and antioxidant enzymes; synthesis and accumulation of anthocyanins, vitamin C, and polyphenols; enhancing abiotic stress through cytokinin and abscisic acid (ABA) production; upregulation of stress-related genes; and the production of exopolysaccharides, secondary metabolites, and ACC deaminase. Azospirillum is a free-living bacterial genus which can promote the yield and growth of many species, with multiple modes of action which can vary on the basis of different climate and soil conditions. Different species of Bacillus spp. can increase the growth, yield, and biomass of plants by increasing the availability of nutrients; enhancing the solubilization and subsequent uptake of nutrients; synthesizing indole-3-acetic acid; fixing nitrogen; solubilizing phosphorus; promoting the production of phytohormones; enhancing the growth, production, and quality of fruits and crops via enhancing the production of carotenoids, flavonoids, phenols, and antioxidants; and increasing the synthesis of indoleacetic acid (IAA), gibberellins, siderophores, carotenoids, nitric oxide, and different cell surface components. The aim of this manuscript is to survey the effects of Azospirillum spp. and Bacillus spp. by presenting case studies and successful paradigms in several horticultural and agricultural plants. Full article

Dark septate endophytes (DSE) may facilitate plant growth and stress tolerance in stressful ecosystems. However, little is known about the response of medicinal plants to DSE, especially under heavy metal stress. This study aimed to investigate how DSE affects the growth of Dendranthema morifolium in medicinal plants under cadmium (Cd) stress. In this investigation, the sterile and non-sterile inoculations were carried out to evaluate the effect of three DSE strains on D. morifolium stressed with Cd. For the root, DSE15 sterile or non-sterile inoculation resulted in enhanced root biomass, root volume, the Cd content of roots, and the indoleacetic acid (IAA) levels in D. morifolium under Cd stress. DSE7 non-sterile inoculation significantly enhanced the Cd content of roots at 1 and 5 mg Cd/kg soil. Regarding impact stems and leaves, under sterile conditions, DSE7 and DSE15 effectively regulated the shoot biomass, plant height, chlorophyll level, and superoxide dismutase (SOD) content. Under sterile conditions, DSE15 positively influenced shoot biomass and plant height, while DSE7 had no significant effect on them when subjected to Cd stress. For effects on flowers under non-sterile conditions, DSE7 and DSE15 significantly increased the flower biomass under Cd stress, while DSE7 reduced the Cd transfer coefficient of flowers at 1 and 5 mg Cd/kg soil. Importantly, at 1 mg Cd/kg soil, DSE7 and DSE15 non-sterile inoculations promoted the 1, 5-dicaffeoylquinic acid content by 18.29% and 21.70%. The interaction between DSE and soil factors revealed that DSE species had significant effects on soil organic carbon and available nitrogen in D. morifolium non-sterile soil. The DSE15 inoculation enhanced soil organic carbon content, while the inoculation of DSE7 and DSE15 reduced soil available nitrogen content under Cd stress. These results contribute to a better understanding of DSE-plant interactions in habitats contaminated by heavy metals and demonstrate the potential utility of DSE strains for cultivating medicinal plants. Full article

This study investigates the environmental significance of ciprofloxacin as an emerging contaminant and the need for effective degradation methods. The chemical coprecipitation method was used in this study to prepare the Zn-Cu-Ni composite silicate, serving as a heterogeneous ozonation catalyst. The catalytic activity was then evaluated by degrading ciprofloxacin (CIP). Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption–desorption, and Fourier transform infrared analysis (FTIR) were used to characterize the Zn-Cu-Ni composite silicate. The catalyst had a high surface area (308.137 m²/g), no regular morphology, and a particle size of 7.6 µm and contained Si-O-Si, Ni-O-Si, and Zn-O-Si. The results showed that the CIP degradation and mineralization rates (pH 7.0, CIP 3.0 mg/L, Ozone 1.5 mg/L) were significantly enhanced in the presence of the Zn-Cu-Ni composite silicate. The CIP and total organic carbon (TOC) removal rates were increased by 51.09% and 18.72%, respectively, under optimal conditions, compared with ozonation alone. The adsorption of Zn-Cu-Ni composite silicate, ozone oxidation, and ·OH oxidation synergistically promoted the efficient removal of CIP. This study provides valuable catalytic ozone technology for degradation of antibiotics in wastewater to reduce environmental pollution with potential practical applications. Full article

Biochar is gaining recognition as a sustainable material, with several applications in soil amendment, carbon sequestration, nutrient dynamics, the remediation of organic contaminants from soil, and water filtration. However, understanding its characteristics is limited due to its intricate structure. This study used response surface methodology (RSM) and artificial neural networks (ANNs) to optimize and predict the production of biochar from the pyrolysis of palm kernel shells. To determine how residence time, nitrogen flow rate, and pyrolysis temperature affected biochar production, a Box–Behnken experimental design was employed. The prediction of the biochar yield was modeled using four different models of ANNs: narrow, medium, wide, and optimum. The physicochemical properties of the biochar produced at pyrolysis temperatures ranging from 400 to 800 °C were determined using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), nitrogen (N₂) physisorption analysis, and field emission scanning electron microscopy (FESEM). With a p-value significantly lower than 0.05, the response surface quadratic model was found to be the most suitable to optimize the biochar yield obtained from the PKS pyrolysis. Biochar production was very sensitive to the three operating parameters: pyrolysis temperature, nitrogen flow rate, and pyrolysis time. With a coefficient of determination (R²) of 0.900, root mean square error (RMSE) of 0.936, and mean absolute error (MAE) of 0.743, the optimized ANN outperformed the other three ANN models tested. When compared to the optimized ANN, the response surface quadratic model with an R² of 0.989 had better prediction of biochar yield. At optimized experimental conditions for nitrogen flow rate (150.01 mL/min), temperature (799.71 °C), and pyrolysis time (107.61 min), a biochar yield of 37.87% was obtained at a desirability function of 1. Full article

The accumulation of aniline in the natural environment poses a potential threat to crops, and thus, investigating the effects of aniline on plants holds practical implications for agricultural engineering and its affiliated industries. This study combined physiological, transcriptomic, and metabolomic methods to investigate the growth status and molecular-level response mechanisms of rice under stress from varying concentrations of aniline. At a concentration of 1 mg/L, aniline exhibited a slight growth-promoting effect on rice. However, higher concentrations of aniline significantly inhibited rice growth and even caused notable damage to the rice seedlings. Physiological data indicated that under aniline stress, the membrane of rice underwent oxidative damage. Furthermore, when the concentration of aniline was excessively high, the cells suffered severe damage, resulting in the inhibition of antioxidant enzyme synthesis and activity. Transcriptomic and metabolomic analyses indicated that the phenylpropanoid biosynthesis pathway became quite active under aniline stress, with alterations in various enzymes and metabolites related to lignin synthesis. In addition to the phenylpropanoid biosynthesis pathway, amino acid metabolism, lipid metabolism, and purine metabolism were also critical pathways related to rice’s response to aniline stress. Significant changes occurred in the expression levels of multiple genes (e.g., PRX, C4H, GST, and ilvH, among others) associated with functions such as antioxidant activity, membrane remodeling, signal transduction, and nitrogen supply. Similarly, notable alterations were observed in the accumulation of various metabolites (for instance, glutamic acid, phosphatidic acid, phosphatidylglycerol, and asparagine, etc.) related to these functions. Our research findings have unveiled the potential of compounds such as phenylpropanoids and amino acids in assisting rice to cope with aniline stress. A more in-depth and detailed exploration of the specific mechanisms by which these substances function in the process of plant resistance to aniline stress (for instance, utilizing carbon-14 isotope tracing to monitor the metabolic pathway of aniline within plants) will facilitate the cultivation of plant varieties that are resistant to aniline. This will undoubtedly benefit activities such as ensuring food production and quality in aniline-contaminated environments, as well as utilizing plants for the remediation of aniline-polluted environments. Full article

Climate change and anthropogenic nitrogen addition alter the soil physicochemical properties and microbial activity in oligotrophic forest soil. Unbalanced and non-selective nitrogen fertilizer application is lost as gas emissions (N₂O, NO) and also contributed to eutrophication through NO₃⁻ leachate. Similarly, NO₃⁻ infiltrates and contaminated drinking water sources lead to human thyroid dysfunction. In order to protect depleting timber growth due to nitrogen deficiency and increasing ecological concerns from nitrogen misapplication, we reviewed the effects of different synthetic nitrogen forms and levels on the biogeochemical process. In this review, we focused on the most recent findings from research articles, review articles, and meta-analyses on forest soil and also followed the complementary insights from agricultural soil so that we may be able to highlight how these observations contribute to the understanding of the forest soil nitrogen cycle. Firstly, we elaborated the role of nitrification and denitrification in the nitrogen transformation process. Secondly, we discussed the effect of different nitrogen forms and levels on nitrification and denitrification functional gene abundances. Thirdly, we analyzed the possible effect of gene abundances on the nitrogen conversion process. Finally, we revealed that different forms and levels of synthetic nitrogen not only alter the nitrogen conversion pathways by increasing the gene abundances through substrate availability but also shift the gene dominance, thereby modifying soil physicochemical properties, such as pH. This collectively changes the conditions, which are critical for gene expression potential involved in the nitrogen conversion process. These findings may create a direction for sustainable and eco-friendly fertilizer application in nitrogen-deficient soil. Full article

Maize double-cropping production systems in Mediterranean areas have a great nitrogen extraction capacity and high nitrogen (N) requirements. This study aims to assess whether in these farming systems, animal manure can be applied, using adequate management practices, at levels exceeding the maximum annual amount of livestock manure established in the European Nitrate Directive for vulnerable zones (170 kg N ha⁻¹) without increasing the risk of water nitrate contamination. We compare the risk of nitrate leaching under two fertilisation strategies, one with synthetic fertilisers and the second with a maximised application of pig slurry, exceeding the limits of the EU Nitrate Directive, in two soil types. Crop yields, N extraction and nitrate concentrations below the crop root zone were not affected by the fertilisation strategies at each site. The results show that pig slurry can be applied above the limit of 170 kg N ha⁻¹ under the conditions of the study, up to 360 kg N ha⁻¹, without increasing the risk for nitrate leaching. Full article

An adaptable, low-cost, and easy-to-operate biological treatment system for pollutant abatement in aquaculture water at the field pond scale needs to be developed. In this study, the pollutant removal capacity of a stable bioreactor for aquaculture wastewater was assessed, and the related mechanism was elucidated via an analysis of the microbial community’s characteristics and functions. The average removal efficiencies of chemical oxygen demand, suspended solids, total nitrogen, and total phosphorus were 40%, 86.22%, 38.62%, and 53.74%, respectively. The effluent quality meets the Requirement for Water Discharge from Freshwater Aquaculture Pond, SC/T9101-2007. The results indicate that the fillers under anaerobic conditions could attract Denitratisoma and unclassified_Rhodocyclaceae, promoting the denitrification reaction. This aligns with the characteristic that total nitrogen in aquaculture sewage mainly exists in the form of nitrate nitrogen. An anaerobic atmosphere helps degrade organic contaminants at liquid interfaces and remove nitrogen in the solid phase. The fillers under anaerobic conditions could attract Bacteroidota and promote the production of polysaccharides to form biofilms, which may be associated with phosphorus removal. The results indicate that the anaerobic stage can promote the formation of biofilm on the fillers to remove pollutants, thus achieving higher aquaculture sewage treatment efficiency. Full article