Search Results (59)

Pesticide residues pose risks to the environment and human health. Little is known about how tillage and straw management affect herbicide behavior in soil. This study investigated the effects of different tillage practices under varying straw incorporation scenarios on the degradation of five commonly used herbicides in a long-term experimental field located in the maize belt of Siping, Jilin Province. Post-harvest soil samples were analyzed for residual herbicide concentrations and basic soil physicochemical properties. A human health risk assessment was conducted, and a controlled incubation experiment was carried out to evaluate herbicide degradation dynamics under three management systems: straw incorporation with traditional rotary tillage (ST), straw incorporation with strip tillage (SS), and no-till without straw (CK). Residual concentrations of atrazine ranged from not detected (ND) to 21.10 μg/kg (mean: 5.28 μg/kg), while acetochlor showed the highest variability (2.29–120.61 μg/kg, mean: 25.26 μg/kg). Alachlor levels were much lower (ND–5.71 μg/kg, mean: 0.34 μg/kg), and neither nicosulfuron nor mesotrione was detected. Soil organic matter (17.6–20.89 g/kg) positively correlated with available potassium and acetochlor residues. Health risk assessments indicated negligible non-cancer risks for both adults and children via ingestion, dermal contact, and inhalation. The results demonstrate that tillage methods significantly influence herbicide degradation kinetics, thereby affecting environmental persistence and ecological risks. Integrating straw with ST or SS enhanced the dissipation of atrazine and mesotrione, suggesting their potential as effective residue mitigation strategies. This study highlights the importance of tailoring tillage and straw management practices to pesticide type for optimizing herbicide fate and promoting sustainable agroecosystem management. Full article

Biochar, as an emerging biotechnology, has been widely used in the remediation of soil organic pollution, mainly by promoting the abundance of related degrading bacteria in soil. In this study, we explored the influence of sewage sludge biochars pyrolyzed at different temperatures of 300–700 °C (SSB₃₀₀-SSB₇₀₀) and addition rates (1% and 5%) on the atrazine biodegradation in soils. After a 21-day incubation, the application of 5% SSB₃₀₀ significantly increased soil catalase (CAT), urease activity, dissolved organic carbon (DOC), and electrical conductivity (EC). However, biochar amendment exhibited inhibitory effects on atrazine degradation in soils. The atrazine degradation ratio decreased with decreasing pyrolysis temperature and increasing addition rates. Further analysis found that there were two possible reasons for the significant decline of atrazine biodegradation in SSB₃₀₀ groups: (1) SSB₃₀₀ demonstrated higher adsorption capacity for atrazine compared to SSB₅₀₀ and SSB₇₀₀ and reduced atrazine bioavailability due to its stronger hydrophobic nature and more abundant surface functional groups; and (2) the SSB₃₀₀ significantly decreased the abundances of dominant atrazine-degraders (Arthrobacter and Pseudomonas) and atrazine-degrading genes (atzA, atzB, and trzN). Full article

This study approaches the characterization of Ferroxite and Hematite and the test of their magnetic properties on the degradation and adsorption of Atrazine, an herbicide of the triazine class. This herbicide was compared with a sample of Ferroxite in the absence of a magnetic field and with Hematite, a non-magnetic material which should not be attracted by the magnet. In the sample, the Atrazine determination was carried out by Fenton analysis. Preliminary results were satisfactory, gathering a reduction rate up to 85% for Ferroxite in the presence of a magnetic field and 53% for Hematite. The Fenton reaction, however, showed an 87% reduction rate for Ferroxite in the presence of a magnetic field, and 56% for Hematite. These findings have shown that there is a relation between the magnetic field intensity and the adsorption capacity for these materials. Full article

Advanced oxidation processes (AOPs) based on activated persulfate (PS) are gradually being employed in the treatment of novel pollutants. In this study, an efficient and reliable CoNiFe-layered double hydroxide (LDH) was prepared by a hydrothermal method, which could effectively activate peroxomonosulfate (PMS) and cause free sulfate radical (SO₄^•−) oxidation to decompose atrazine (ATZ). The degradation rate of ATZ was greater than 99% within 60 min at pH 7 when the initial concentration of ATZ was 10 mg·L⁻¹, and the dosages of PMS and activator were 0.6 mM and 80 mg·L⁻¹. The analysis of ATZ degradation confirmed the reusability of the activator and its strong structural stability. The generation of four free radicals was analyzed and confirmed, and the influence on the degradation reaction was SO₄^•− > O₂^•− > ¹O₂ > •OH. The analytical results showed that the metal ions reacted with HSO₅⁻ in PMS to cause an oxidation–reduction cycle change in the valence state of the metal ions and generated the primary factor affecting the degradation reaction—SO₄^•−. Nine degradation intermediates with reduced toxicity were detected and possible ATZ degradation pathways were deduced, thus confirming the activation mechanism of CoNiFe-LDH. Full article

In this study, a halotolerant bacterial strain was isolated and identified. This bacterium was confirmed to efficiently degrade s-triazine herbicides under saline conditions. The optimal conditions for the metabolism and growth of this strain were determined through single-factor tests. Furthermore, the biodegradation pathways of prometryne (the target compound) by this strain were proposed based on the detection of possible degradation intermediates and genome sequencing analysis. Additionally, a possible halotolerance mechanisms of this strain were also revealed through screening halotolerance-related genes in its genome. The results demonstrated that a halotolerant bacterial strain (designated PC), which completely degraded 20.00 mg/L prometryne within 12 h under saline conditions (30.0 g/L NaCl), was isolated and identified as Paenarthrobacter ureafaciens. The optimal conditions for the metabolism and growth of the strain PC were identified as follows: yeast extract as the additional carbon source with the concentration of ≥0.1 g/L, NaCl concentration of ≤30.0 g/L, initial pH of 7.0, temperature of 35.0 °C, and shaking speed of ≥160 rpm. Furthermore, the strain PC demonstrated efficient removal of other s-triazine herbicides, including atrazine, ametryne, simetryne, and cyanazine. The strain PC might degrade prometryne through a series of steps, including demethylthiolation, deisopropylamination, deamination, dealkalation, decarboxylation, etc., relying on the relevant functional genes involved in the degradation of s-triazine compounds. Furthermore, the strain PC might tolerate high salinity through the excessive uptake of K⁺ into cells, intracellular accumulation of compatible solutes, and production of halophilic enzymes. This study is expected to provide a potentially effective halotolerant bacterium for purifying s-triazine pollutants in saline environments. Full article

The increasing presence of pollutants, including pharmaceuticals and pesticides, in water resources necessitates the development of effective remediation technologies. Zeolites are promising agents for pollutant removal due to their high surface area, ion-exchange capacity, natural abundance, and diverse tailorable porous structures. This review focuses on the efficient application of modified zeolites and mesoporous materials as photocatalysts and adsorbents for removing contaminants from water bodies. The adsorption and photodegradation of pesticides and selected non-steroidal anti-inflammatory drugs and antibiotics on various zeolites reveal optimal adsorption and degradation conditions for each pollutant. In most reported studies, higher SiO₂/Al₂O₃ ratio zeolites exhibited improved adsorption, and thus photodegradation activities, due to increased hydrophobicity and lower negative charge. For example, SBA-15 demonstrated high efficiency in removing diclofenac, ibuprofen, and ketoprofen from water in acidic conditions. Metal doped into the zeolite framework was found to be a very active catalyst for the photodegradation of organic pollutants, including pesticides, pharmaceuticals, and industrial wastes. It is shown that the photocatalytic activity depends on the zeolite-type, metal dopant, metal content, zeolite pore structure, and the energy of the irradiation source. Faujasite-type Y zeolites combined with ozone achieved up to 95% micropollutant degradation. Bentonite modified with cellulosic biopolymers effectively removed pesticides such as atrazine and chlorpyrifos, while titanium and/or silver-doped zeolites showed strong catalytic activity in degrading carbamates, highlighting their environmental application potential. Full article

Atrazine causes serious contamination of agricultural soils and groundwater. This study investigated the influence mechanism of sterilized soil (CKs), unsterilized soil (CKn), sterilized soil amended with 45 (SsV1), 60 (SsV2), 75 (SsV3) days of vermicompost (the maturity days of vermicompost), and unsterilized soil amended with 45 (SnV1), 60 (SnV2), 75 (SnV3) days of vermicompost on atrazine catabolism. The atrazine degradation experiment lasted for 40 days. The results showed that the atrazine degradation rates for CKs, CKn, SsV1, SsV2, SsV3, SnV1, SnV2, and SnV3 were 24%, 56.9%, 62.8%, 66.1%, 65.9%, 87.5%, 92.9%, and 92.3%, respectively. Indigenous microorganisms capable of degrading atrazine were present in unsterilized soil, and the addition of vermicompost enhanced atrazine degradation. The humic acid content of SnV2 was the highest, at 4.11 g/kg, which was 71.97% higher than that of CKn. The addition of the vermicompost enhanced the production of hydroxyatrazine, deethylatrazine, and deisopropylatrazine. Vermicompost increased the abundance of atrazine-degrading bacteria (Mycobacterium, Devosia, etc.), and introduced new atrazine-degrading bacteria (Mesorhizobium, Demequina). The above results showed that the best degradation of atrazine was achieved with 60 days of vermicompost addition. This study provides a new, efficient, economical, and environmentally friendly strategy for the remediation of atrazine-contaminated soil. Full article

The widespread occurrence of atrazine (ATZ) in water environments presents a considerable risk to human health and ecosystems. Herein, the performance of dielectric barrier discharge integrated with periodate (DBD/PI) for ATZ decomposition was evaluated. Results demonstrated that the DBD/PI system improved ATZ decomposition efficiency by 18.2–22.5% compared to the sole DBD system. After 10 min treatment, the decomposition efficiency attained 82.4% at a discharge power of 68 W, a PI dosage of 0.02 mM, and an initial ATZ concentration of 10 mg/L. As the PI dosage increased, the decomposition efficiency exhibited a trend of initially increasing, followed by a decrease. Acidic conditions were more favorable for ATZ removal compared to alkaline and neutral conditions. Electron paramagnetic resonance (EPR) was adopted for characterizing the active species produced in the DBD/PI system, and quenching experiments revealed their influence on ATZ decomposition following a sequence of ¹O₂ > O₂⁻• > IO₃• > OH•. The decomposition pathways were proposed based on the theoretical calculations and intermediate identification. Additionally, the toxic effects of ATZ and its intermediates were assessed. This study demonstrates that the DBD/PI treatment represents an effective strategy for the decomposition of ATZ in aquatic environments. Full article

Pesticide residues in soil, especially multiple herbicide residues, cause a series of adverse effects on soil properties and microorganisms. In this work, the degradation of three herbicides and the effect on bacterial communities under combined pollution was investigated. The experimental results showed that the half-lives of acetochlor and prometryn significantly altered under combined exposure (5.02–11.17 d) as compared with those of individual exposure (4.70–6.87 d) in soil, suggesting that there was an antagonistic effect between the degradation of acetochlor and prometryn in soil. No remarkable variation in the degradation rate of atrazine with half-lives of 6.21–6.85 d was observed in different treatments, indicating that the degradation of atrazine was stable. 16S rRNA high-throughput sequencing results showed that the antagonistic effect of acetochlor and prometryn on the degradation rate under combined pollution was related to variation of the Sphingomonas and Nocardioide. Furthermore, the potential metabolic pathways of the three herbicides in soil were proposed and a new metabolite of acetochlor was preliminarily identified. The results of this work provide a guideline for the risk evaluation of combined pollution of the three herbicides with respect to their ecological effects in soil. Full article

Understanding the degradation kinetics and mechanisms of trace organic contaminants (TrOCs) by UV-based advanced oxidation processes (UV-AOPs) are pivotal in realizing their efficient application in water treatment. However, the relevant knowledge in practical flow-through reactors remains a void, compared with that of commonly used batch reactors. To fill the knowledge gaps, the current work investigated the degradation of atrazine (ATZ) in flow-through UV-AOP systems with different light sources and chlorine additions. The results showed that UV/Cl₂ in the reactors (with a diameter of 50 mm) was not very efficient in ATZ degradation while the pseudo-first order degradation rate constant was elevated by over 2.7 times with vacuum UV (VUV)/UV. In contrast to observations in the batch reactors, the addition of chlorine to the flow-through VUV/UV system unexpectedly decreased the rate constant by about 39%. The analysis of the relative contributions of different degradation pathways revealed that the inhibitory effect of the chlorine addition arose from the transformation of HO^• to reactive chlorine species (e.g., ClO^•) which had low reaction rate constants with ATZ. The baffle implementation promoted the ATZ degradation by 12–58%, mainly due to an enhanced mixing that facilitated the radical oxidation. The energy costs of the UV-AOPs in ATZ removal ranged within 0.40–1.11 kWh m⁻³ order⁻¹. The findings of this work are helpful in guiding efficient VUV/UV and VUV/UV/Cl₂ processes in drinking water treatment. Full article

Pesticide contamination of aquatic ecosystems poses a significant threat to humans and can adversely affect fungal-driven processes in these understudied habitats. Here, we investigated the effects of four pesticides on detritus-inhabiting and plant root-associated fungi from streams, peatlands, and saltwater marshes. Additionally, we assessed the isolates’ capacities to degrade three carbon sources to understand the impact of pesticides on fungal-driven processes. Pesticide assays were conducted in 96-well glass-coated plates, with fungal growth measured using a UV-Vis spectrophotometer set to 595 nm. Assays included technical replication (n = 6), replication over time (n = 2), negative controls, and carry-over controls. In total, we assayed more than 153 isolates, representing up to 97 fungal genera. Results showed that 1.9%, 49.7%, 3.1%, and 5.6% of the isolates exhibited consistently lower growth when exposed to atrazine, mancozeb, cypermethrin, and malathion, respectively. Furthermore, 101 isolates, comprising 87 genera, were tested for cellulase, starch degradation, and tannase activity, with 41.6%, 28.7%, and 30.7% of the isolates testing positive, respectively. These findings suggest that while many species demonstrate functional redundancy, some fungal species are sensitive to current environmental pesticide levels, which affects their growth and may have broader implications on ecosystem health. Full article

In the past, the application of TiO₂ slurry reactors has faced difficulties concerning the recovery and reusability of the catalyst. In response to these challenges, immobilized photocatalyst systems have been investigated, wherein the catalyst is fixed onto a solid support, frequently with reduced photocatalytic performance. In the present study, thin TiO₂ films were developed in the anatase phase by the sol-gel process and spin-cast on laser-microstructured silicon substrates, to form photocatalytic surfaces of increased activity. The TiO₂ films were thoroughly characterized using SEM-EDX, XRD, UV–Vis spectroscopy, and Raman spectroscopy. The photocatalytic activity of these surfaces was evaluated by the degradation of atrazine in aqueous solution under UV irradiation. Their photocatalytic activity was found to be significantly enhanced (mean k_obs 24.1 × 10⁻³ min⁻¹) when they are deposited on laser-microstructured silicon compared with flat silicon (mean k_obs 4.9 × 10⁻³ min⁻¹), approaching the photocatalytic activity of sol-gel TiO₂ fortified with Degussa P25, used as a reference material (mean k_obs 32.7 × 10⁻³ min⁻¹). During the photocatalytic process, several transformation products (TPs) of atrazine, namely 2-chloro-4-(isopropylamino)-6-amino-s-triazine (CIAT), 2-chloro-4-amino-6-(ethylamino)-s-triazine (CAET), and 2-chloro-4.6-diamino-s-triazine (CAAT), were identified with LC–MS/MS. The stability of the photocatalytic surfaces was also investigated and remained unchanged through multiple cycles of usage. The surfaces were further tested with two other pollutants, i.e., 2,4,6-trichlorophenol and bisphenol-a, showing similar photocatalytic activity as with atrazine. Full article

Pesticides are widely detected in large quantities in the environment, posing an ecological threat to the human body and ecology. Semiconductor nanomaterials such as nano-titania (nTiO₂) have strong photocatalytic degradation efficiency for pollutants. However, the wide bandgap and limited light absorption range inhibit nano-titania’s practical application. Therefore, nTiO₂ was modified by Fe³⁺ doping using the microwave hydrothermal method to improve its photocatalytic performance in this study. Fe-nTiO₂ doped with a 1.0% mass ratio was used due to its high photocatalytic performance. Its maximum degradation efficiencies for ACE and ATZ under a 20 W xenon lamp were 88% and 88.5%, respectively. It was found that Fe³⁺ doping modification distorted the spatial morphology of nTiO₂ and shortened the bandgap to facilitate the photocatalytic reaction. The electron paramagnetic resonance results showed that the reactive radicals (¹O₂, ·OH) produced by photogenerated electrons (e⁻) and holes (h⁺) of Fe-nTiO₂ were the main active species in the degradation of ACE and ATZ. Additionally, the application of Fe-nTiO₂ significantly enhanced the growth of lettuce under sunlight; the degradation efficiencies of ACE and ATZ in lettuce were 98.5% and 100%, respectively. This work provides new insights into the removal of organic contaminants by photocatalysts under sunlight in agriculture. Full article

Atrazine is one of the most widely used herbicide molecules in the triazine family. Despite its interdiction in the European Union in 2004, atrazine and its main degradation products remain among the most frequently found molecules in freshwater reservoirs in many European Union countries. Our study aims in obtaining insight into the desorption process of atrazine from the main soil absorbent material: clay. Constrained Molecular Dynamics simulations within the Density Functional Theory framework allow us to obtain a free energy desorption profile of atrazine from a Ca²⁺-montmorillonite surface. The results are interpreted in terms of atrazine inclination to the clay surface and moreover, in terms of hydration states of the cations present in the clay interlayer as well as the hydration state of the atrazine. The desorption mechanism is driven by atrazine alkyl groups and their sizes because of dispersion stabilizing effects. The highest barrier corresponds to the loss of the isopropyl interaction with the surface. Full article

To investigate the effect of pesticide use on surface water, the concentration and distribution characteristics of 57 pesticides and 3 degradation products were analyzed in the farmland soil and surface water in the Xingkai Lake area, including water from paddy fields, drainages and the Xingkai Lake, in Heilongjiang Province, China. Forty-three pesticides and three degradation products were detected in farmland soil. In dry field (corn and soybean field) soil, the main detected pesticides were atrazine and acetochlor with mean concentrations of 26.09 ng·g⁻¹ and 49.08 ng·g⁻¹, respectively. In paddy field soil, oxadiazon, mefenacet and chlorpyrifos were the main detected pesticides with mean concentrations of 14.32 ng·g⁻¹, 78.60 ng·g⁻¹ and 20.03 ng·g⁻¹, respectively. In the surrounding water, including water from paddy fields, drainages and Xingkai Lake, the total concentrations of contaminants detected in the water samples ranged from 71.19 ng·L⁻¹ to 10,145.76 ng·L⁻¹. Of the three sampling periods, the mean concentration of contaminants in the water exhibited its peak during the vegetative period. In the analysis of the drainage water, the primary pesticides detected were atrazine, acetochlor and buprofezin with mean concentrations of 354.83 ng·L⁻¹, 109.09 ng·L⁻¹ and 254.56 ng·L⁻¹, respectively. Atrazine, simetryn, buprofezin and isoprothiolane were the main pesticides detected in Xingkai Lake water, with the mean concentrations of 222.35 ng·L⁻¹, 112.76 ng·L⁻¹, 301.87 ng·L⁻¹ and 138.02 ng·L⁻¹, respectively. The concentrations of contaminants could be correlated with drainage, Da Xingkai Lake and Xiao Xingkai Lake water (ρ > 0.8) suggested that the source of these contaminants in drainage and Xingkai Lake water could be the same. The maximum potentially affected fraction (PAF) values of atrazine, chlorpyrifos and prometryn were higher than 5% in Xingkai Lake water, resulting in high ecological risks. Full article