Degradation Of Terbuthylazine Research Articles

Biodegradation characteristics and mechanism of terbuthylazine by the newly isolated Agrobacterium rhizogenes strain AT13

Terbuthylazine (TBA) is an emerging environmental contaminant that poses moderate to high risk to non-target organisms. In this study, a newly TBA-degrading strain, Agrobacterium rhizogenes AT13, was isolated. This bacterium degraded 98.7% of TBA (100 mg/L) within 39 h. Based on the six detected metabolites, three novel pathways of strain AT13, including dealkylation, deamination–hydroxylation, and ring-opening reactions, were proposed. The risk assessment demonstrated that most degradation products might be substantially less harmful than TBA. Whole-genome sequencing and RT-qPCR analysis revealed that ttzA, which encodes S-adenosylhomocysteine deaminase (TtzA), is closely related to TBA degradation in AT13. Recombinant TtzA showed 75.3% degradation of 50 mg/L of TBA within 13 h and presented a Km value of 0.299 mmol/L and a Vmax value of 0.041 mmol/L/min. The molecular docking results indicated that the binding energy of TtzA to TBA was −32.9 kcal/mol and TtzA residue ASP161 formed two hydrogen bonds with TBA at distances of 2.23 and 1.80 Å. Moreover, AT13 efficiently degraded TBA in water and soil. Overall, this study provides a foundation for the characterization and mechanism of TBA biodegradation and may enhance our understanding of the TBA biodegradation by microbes.

Influence of tillage systems on terbuthylazine degradation and leaching in the soil

The aim of the study was to evaluate the effect of the cultivation system on the rate of degradation and movement of terbuthylazine in the soil. Model experiments were carried out on soil taken from the field, parts of which were differentiated for 3 years in terms of the cultivation system: conventional (with pre-winter ploughing), reduced (disk harrow + tillage unit) and zero tillage (no tillage – applica­tion of glyphosate-containing herbicide + direct sowing). The soil was collected with a Van der Horst core sampler into the columns. In a stationary spray chamber, a herbicide containing terbuthylazine was applied at the recommended dose of 500 g/ha. On the basis of the conducted research, it was found that terbuthylazine is a substance with medium persistence in soil (DT50 = 27–34 days). This substance shows the slowest degradation in soil with a zero tillage system. On the other hand, the lack of disturbing the soil structure has a positive effect on the mobility of the herbicide, allowing it to move faster outside the plant root zone.

Degradation of terbuthylazine by Fe/TiO2 with visible-light-driven photo-Fenton catalytic activity

In order to improve the catalytic activity of Fenton catalyst, a composite catalyst, Fe/TiO2, with both visible-light photocatalytic and Fenton-like catalytic activities was synthesized via a brief solvothermal process. The XRD and SEM results indicated that Fe was dispersed homogeneously on the surface of TiO2 in the form of Fe2O3, and the loading of Fe did not have significant effects on the particle size and morphology of TiO2. The EDS results showed that the loading content of Fe was about 1.4 wt%. The photocatalytic results showed that the prepared Fe/TiO2 composite catalyst had excellent catalytic behaviors for terbuthylazine degradation under visible-irradiation with H2O2 assistance, the degradation ratio reached up to 90% after 120 min. The reinforced degradation performance were primarily attributable to the introduction of carrier TiO2, which expanded visible response range by H2O2 adsorption, and accelerated the cycle of Fe (Ⅱ)/Fe (Ⅲ). The fluorescent spectroscopy results revealed that the degradation process of terbuthylazine involved the generation and participation of active species such as hydroxyl radicals and superoxide radicals. This study is expected to provide a visual approach for designing a novel photo-Fenton catalyst to jointly utilize both photocatalytic and Fenton activities, which can be better applied to the actual use of organics purification in wastewater.

Comparative Effect of UV, UV/H2O2 and UV/H2O2/Fe on Terbuthylazine Degradation in Natural and Ultrapure Water.

Different advanced oxidation processes (AOPs) (ultraviolet radiation, hydrogen peroxide photolysis and photo-Fenton) were applied to test the degradation of terbuthylazine in three types of water: (a) ultrapure water, (b) surface water from the Gaditana area (Los Hurones reservoir, Cádiz, Spain) and (c) groundwater from the Tempul spring in Jerez de la Frontera (Cádiz, Spain). The experiments were carried out on a laboratory scale, using two different types of reactors, batch and semi-continuous. In batch reactors, the most efficient process for the experiments carried out with both ultrapure water and underground groundwater was ultraviolet radiation, whereas for surface water from the Gaditana area, the process that obtained the best results was the photolysis of hydrogen peroxide with 2.5 mg L−1 of H2O2. In semi-continuous reactors, the most efficient process was the photolysis of hydrogen peroxide with 2.5 mg L−1 of H2O2 for all the matrices studied. In both types of reactors, terbuthylazine degradation percentages higher than 90% were achieved; the main difference was in the reaction time, which varied from minutes in the batch reactor to seconds in the semi-continuous reactor. In all the applied AOPs, N-terbutyl-6-hydroxy-N′ethyl-1,3,5-triazine-2,4-diamine (TBA-212) was generated as a reaction intermediate.

Insights into the photoinduced degradation of terbuthylazine from aqueous solution: The synergic effects generated from hydrogen-bond interactions

In this work, we examined the stability of terbuthylazine (TBA) as well as the mechanisms related to its photoinduced degradation considering two conditions: i) when exposed (solely) to UV radiation and ii) when exposed to UV radiation in presence of H2O2. Ground state properties (such as bond lengths, hydrogen-bond interactions, and relative energetics) as well as excited state parameters (vertical excitation energies and generalized oscillator strengths, GOS) were determined through the use of standard and well documented density functional theory based electronic structure methods and, subsequently, explored for accomplishing the purpose of the work; results were obtained considering both the gas-phase and a (water) solvent environment. In terms of ground state, the presence of the additional hydrogen-bond interaction when the H2O2 molecule is nearing the N atom located in the opposite side to the Cl atom in TBA suggested the system to be more stable (for instance, 9.93 kJ/mol at the CAM-B3LYP/aug-cc-pVTZ level of theory in water) than its counterpart with the H2O2 molecule neighboring the N and Cl atoms. The excitation energies determined considering solvation were found to be in fairly good agreement when compared to the corresponding obtained in the gas-phase. Interestingly and more important, a different situation is observed in terms of GOS when solvation is considered. In this case, two excited states (versus no state in the gas-phase) were found to have considerably large GOS and, thus, are expected to be accessible at the UV region. Therefore, the interactions between TBA, H2O2, and water molecules (from the solvent environment) play an important role in regards to the excited states to be accessed. By coexisting with the UV photolysis of the H2O2 molecules in aqueous solution, the synergic effects from the TBA-H2O2-H2O interactions may add to the enhancement in the yield of the photoinduced degradation of TBA.

Effect of sewage amendment on the dissipation of terbuthylazine, its degradation compound desethyl-terbuthylazine, and S-metolachlor in a field study

This study evaluates the effect of sewage amendment (SA) on the dissipation of terbuthylazine, its degradation compound desethyl-terbuthylazine, and S-metolachlor in the soil. The experiment was conducted at Padua Experimental Farm (Italy). Herbicides dissipation was evaluated in soils differently fertilized for three years: with inorganic fertilizer, with sewage sludge, and with a combination of them. Terbuthylazine and S-metolachlor were applied on sorghum as a formulated product at a dose of 2.8 L ha−1, and their dissipation was followed for 2.5 months. The concentrations of herbicides and one metabolite in soil were analyzed by liquid chromatography-mass spectrometry. The dissipation of terbuthylazine and S-metolachlor followed a pseudo first order kinetics; they dissipated faster in soil amended only with inorganic fertilizer than in soils amended with sewage or sewage + inorganic fertilizer. The reduction in mineralization of the herbicides after sewage addition can be attributed to the reduced herbicide availability to microorganisms. The degradation of terbuthylazine led to the formation of desethyl-terbuthylazine. SA slowed down the formation and the degradation of desethyl-terbuthylazine, leading to a higher amount measured at the end of the incubation. These findings have practical implications for the assessment of the environmental fate of terbuthylazine and S-metolachlor in agricultural areas.

Effect of crystalline structure on terbuthylazine degradation by H2O2-assisted TiO2 photocatalysis under visible irradiation

Various methods for shifting the optical response of TiO2 into the visible (Vis) range have been reported. Herein, we reported the application of a TiO2/H2O2/Vis process and the effects of TiO2 crystalline structure on the degradation of terbuthylazine. The results indicated that TiO2 crystalline structure and H2O2 addition had significant effects on terbuthylazine degradation: its degradation rate could be increased from 7% to 70% with H2O2 addition after 180 min of reaction, the synergistic degradation of terbuthylazine by TiO2-Fe3+ was substantially accelerated, with the degradation rate reaching up to 100% after 20 min of reaction, and rutile TiO2 showed better photocatalytic activity and a more obvious synergistic effect than anatase TiO2. The addition of free-radical scavengers (tert-butyl alcohol or methanol) inhibited the degradation efficiency of rutile TiO2, but had a relatively minor effect on anatase TiO2. Fluorescence spectrophotometry analysis indicated that hydroxyl free radicals could be continuously produced when using rutile TiO2 as the photocatalyst. Degradation of terbuthylazine catalyzed by rutile TiO2 occurred mainly in solution, but occurred on the particle surface of the photocatalyst when catalyzed by anatase TiO2. This study provides new insight into the role of TiO2 crystalline structure on the degradation of terbuthylazine and its photocatalytic degradation mechanism.

Photocatalytic degradation of terbuthylazine: Modelling of a batch recirculating device

Abstract A thin layer photocatalyst using chitosan to immobilize TiO2 on a glass fiber woven roving material was successfully used for photocatalytic degradation of terbuthylazine, s model s-triazine herbicide. The reaction was conducted in a photocatalytic recirculating reactor with the photocatalyst inserted as a removable module. The experimental reaction system employed in this study was composed of an annular photoreactor with the immobilized TiO2/chitosan layer and the radiation source and the second part of the reaction system only used for the aeration or the reaction mixture, both operating in unsteady conditions. The kinetic model is based on a simplified consecutive degradation of terbuthylazine to cyanuric acid through intermediate products. The model of the annular reactor is represented by a hyperbolic partial differential equation solved by method of characteristics; the model of the aeration vessel is given by an ordinary differential equation. The proposed model represents a simple way to describe a complex recirculating reactor system operating in unsteady conditions.

Seasonal variation of chloro-s-triazines in the Hartbeespoort Dam catchment, South Africa

Seasonal variation of eight chloro-s-triazine herbicides and seven major atrazine and terbuthylazine degradation products was monitored in the Hartbeespoort Dam catchment using gas chromatography–mass spectrometry (GC–MS) and liquid chromatography-mass spectrometry (LC-MS/MS). Lake, river and groundwater were sampled from the Hartbeespoort Dam catchment over four seasons and the downstream Jukskei River was monitored during the winter season. Triazine herbicide concentrations in the Hartbeespoort Dam were in the order atrazine>simazine>propazine>ametryn>prometryn throughout the four seasons sampled. Triazine herbicide concentrations in the Hartbeespoort Dam surface water were highest in summer and gradually decreased in successive seasons of autumn, winter and spring. Terbuthylazine was the only triazine herbicide detected at all sampling sites in the Jukskei River, though atrazine recorded much higher concentrations for the N14 and Kyalami sites, with concentrations of 923 and 210ngL−1 respectively, compared to 134 and 74ngL−1 for terbuthylazine. Analytical results in conjunction with river flow data indicate that the Jukskei and Crocodile Rivers contribute the greatest triazine herbicide loads into the Hartbeespoort Dam. No triazine herbicides were detected in the fish muscle tested, showing that bioaccumulation of triazine herbicides is negligible. Atrazine and terbuthylazine metabolites were detected in the fish muscle with deethylatrazine (DEA) being detected in both catfish and carp muscle at low concentrations of 0.2 and 0.3ngg−1, respectively. Desethylterbuthylazine (DET) was detected only in catfish at a concentration of 0.3ngg−1. With atrazine herbicide groundwater concentrations being >130ngL−1 for all seasons and groundwater ∑triazine herbicide concentrations ranging between 527 and 367ngL−1, triazine compounds in the Hartbeespoort Dam catchment may pose a risk to humans and wildlife in light findings of endocrine and immune disrupting atrazine effects by various researchers.

The chronic effects of terbuthylazine-2-hydroxy on early life stages of marbled crayfish (Procambarus fallax f. virginalis)

This study assessed the chronic effects of terbuthylazine-2-hydroxy (T2H), one of the main terbuthylazine degradation products, on early life stages of marbled crayfish (Procambarus fallax f. virginalis) by means of mortality, growth rate, early ontogeny, oxidative stress, antioxidant defence and histopathology. The crayfish were exposed to four concentrations of the tested substance as follows: 0.75μg/l (environmental concentration), 75, 375 and 750μg/l for 62days. Concentrations over 75μg/l caused lower weight compared to the control group. T2H at 750μg/l caused delay in ontogenetic development. Levels of thiobarbituric acid reactive substances and total superoxide dismutase activity were significantly (p<0.01) lower in groups exposed to 375 and 750μg/l T2H. Crayfish in these treatments also showed alteration of tubular system including disintegration of tubular epithelium with complete loss of structure in some places of hepatopancreas and wall thinning up to disintegration of branchial filaments with focal infiltrations of hemocytes. In conclusion, chronic terbuthylazine-2-hydroxy exposure in concentrations up 75μg/l (100 times higher than environmental concentration) affected growth, ontogenetic development, antioxidant system, caused oxidative stress and pathological changes in hepatopancreas of early life stages of marbled crayfish.

Effects of terbuthylazine-desethyl, a terbuthylazine degradation product, on red swamp crayfish (Procambarus clarkii)

Terbuthylazine is a widely used triazine pesticide. This, together with one of its degradation products, terbuthylazine-desethyl (TD), are frequently found in quantities exceeding the EU limit of 0.1μg/L in aquatic ecosystems where they might constitute a serious risk to non-target organisms. The sub-chronic effects of TD at 2.9μg/L (real environmental concentration) and at 580μg/L were investigated in a non-target aquatic species, the red swamp crayfish (Procambarus clarkii). Gill and hepatopancreas histopathology, alterations in biochemical parameters of haemolymph, oxidative damage to hepatopancreas, and changes in antioxidant biomarkers in muscle and hepatopancreas were recorded at both tested concentrations after 14days exposure. A 14day recovery period in TD-free water was not sufficient for restoration of normal parameters. Chronic terbuthylazine-desethyl exposure affected biochemical profile, and the antioxidant system, caused oxidative stress and histopathological changes in hepatopancreas of red swamp crayfish.

Insights into the removal of terbuthylazine from aqueous solution by several treatment methods

This paper reports the removal of the s-triazine herbicide terbuthylazine (TBA) from aqueous solution by various treatment methods including adsorption onto activated carbon (AC) and multiwalled carbon nanotubes (MWCNT), UV254 photolysis, UV254/H2O2, single ozonation, O3/H2O2, catalytic ozonation (AC, MWCNT and TiO2 as catalysts) and some solar driven processes such as TiO2 photocatalytic oxidation and photo-ozonation. TBA was adsorbed onto AC and MWCNT following a pseudo-second order kinetics and Freundlich isotherm. Rapid small scale column tests showed that TBA could be removed from solution by adsorption onto AC better than atrazine. The UV254/H2O2 treatment resulted in excellent removal of TBA primarily due to the oxidation capability of hydroxyl radicals (kHO = 3.3109 M−1 s−1) generated from H2O2 photolysis. As the H2O2 initial concentration was increased from 5 to 50 mg L−1 the HO exposure per UV fluence (RHO,UV) increased, making the process more efficient. Single ozonation also allowed complete removal of the herbicide though the process was slow (kO3=15.4 M−1 s−1 at pH > 4). The ozonation process could be greatly accelerated by the enhanced generation of HO through O3/H2O2 and O3/AC processes, which also led to more efficient processes in terms of ozone utilization. Commercial TiO2 (TiO2-P25) and lab prepared anatase TiO2 (TiO2-cat) nanoparticles catalyzed the removal of TBA by solar photocatalysis. In contrast, a lab prepared MWCNT-TiO2 composite was not useful as catalyst in solar photo-oxidation processes because of the HO scavenging nature of the MWCNT used as support. A mechanism for TBA degradation by O3 and HO has been suggested after TBA degradation intermediates identification.

Exploring the potential of novel biomixtures and Lentinula edodes fungus for the degradation of selected pesticides. Evaluation for use in biobed systems

An approach to reduce the contamination of water sources with pesticides is the use of biopurificaction systems. The active core of these systems is the biomixture. The composition of biomixtures depends on the availability of local agro-industrial wastes and design should be adapted to every region. In Portugal, cork processing is generally regarded as environmentally friendly and would be interesting to find applications for its industry residues. In this work the potential use of different substrates in biomixtures, as cork (CBX); cork and straw, coat pine and LECA (Light Expanded Clay Aggregates), was tested on the degradation of terbuthylazine, difenoconazole, diflufenican and pendimethalin pesticides. Bioaugmentation strategies using the white-rot fungus Lentinula edodes inoculated into the CBX, was also assessed. The results obtained from this study clearly demonstrated the relevance of using natural biosorbents as cork residues to increase the capacity of pesticide dissipation in biomixtures for establishing biobeds. Furthermore, higher degradation of all the pesticides was achieved by use of bioaugmented biomixtures. Indeed, the biomixtures inoculated with L. edodes EL1 were able to mineralize the selected xenobiotics, revelling that these white-rot fungi might be a suitable fungus for being used as inoculum sources in on-farm sustainable biopurification system, in order to increase its degradation efficiency. After 120days, maximum degradation of terbuthylazine, difenoconazole, diflufenican and pendimethalin, of bioaugmented CBX, was 89.9%, 75.0%, 65.0% and 99.4%, respectively..The dominant metabolic route of terbuthylazine in biomixtures inoculated with L. edodes EL1 proceeded mainly via hydroxylation, towards production of terbuthylazine-hydroxy-2 metabolite.Finally, sorption process to cork by pesticides proved to be a reversible process, working cork as a mitigating factor reducing the toxicity to microorganisms in the biomixture, especially in the early stages.

Photocatalytic degradation of the herbicide terbuthylazine: Preparation, characterization and photoactivity of the immobilized thin layer of TiO2/chitosan

The aim of this study was to immobilize a photocatalytic TiO2 layer on a suitable support material for potential use in a variety of photoreactor designs. The immobilized TiO2/chitosan thin film was used for the photocatalytic treatment of a triazine herbicide, terbuthylazine as representative agrochemical pollutant in the wastewater. The method of preparation was based on the use of a chitosan as binder and glass fiber woven roving material as a support. The employed method was found to be very simple, low cost and quite effective. Several methods of the photocatalyst characterization, such as FE-SEM/EDX, AAS, ICP-MS, TOC and nitrogen adsorption/desorption at 77 K were employed to correlate structural and morphological properties of immobilized TiO2–chitosan/glass fiber woven roving and its photocatalytic properties under UV irradiation. Reaction was performed in a self-constructed batch mode and annular type of the photoreactor. Comparison of thermal, photolytic and photocatalytical degradation of treated terbuthylazine at different reaction conditions was performed in order to get more insight into the photocatalytic performance and reaction mechanism. It was observed that there is no decay in photocatalytic efficiency over a long period of reaction time using for the photocatalytic degradation of terbuthylazine.

Solarization and biosolarization using organic wastes for the bioremediation of soil polluted with terbuthylazine and linuron residues

Strategies for remediation of polluted soils are needed to accelerate the degradation and natural attenuation of pesticides. This study was conducted to assess the effect of solarization (S) and biosolarization (BS) during the summer season using organic wastes (composted sheep manure and sugar beet vinasse) for the bioremediation of soil containing residues of terbuthylazine and linuron. The results showed that both S and BS enhanced herbicide dissipation rates compared with the non-disinfected control, an effect which was attributed to the increased soil temperature and organic matter. Linuron showed similar behavior under S and BS conditions. However, terbuthylazine was degraded to a greater extent in the biosolarization experiment using sugar beet vinasse than in the both the solarization and biosolarization experiments using composted sheep manure treatments. The main organic intermediates detected during the degradation of terbuthylazine and linuron were identified, enabling the main steps of degradation to be proposed. The results confirm that both S and BS techniques can be considered as a remediation tools for polluted soils containing these herbicides.

Quantitative and qualitative differences in the metabolism of pesticides in biobed substrates and soil

Biobed substrates commonly exhibit high degradation capacity. However, degradation does not always lead to detoxification and information on the metabolic pathways of pesticides in biobeds is scarce. We studied the degradation and metabolism of three pesticides in selected biomixtures and soil. Biomixtures stimulated degradation of terbuthylazine and metribuzin, whereas chlorpyrifos degraded faster in soil. The latter was attributed to the lipophilicity of chlorpyrifos which increased adsorption and limited biodegradation in organic-rich biomixtures. Although the same metabolites were detected in all substrates, qualitative and quantitative differences in the metabolic routes of pesticides in the various substrates were observed. Chlorpyrifos was hydrolyzed to 3,5,6-tricholorpyridinol (TCP) which was further degraded only in compost-biomixture CBX1. Metabolism of terbuthylazine in compost biomixtures (BX) and soil resulted in the formation of desethyl-terbuthylazine (DES) which was fully degraded only in the compost-biomixture CBX2, whereas peat-based biomixture (OBX) promoted the hydroxylation of terbuthylazine. Desamino- (DA) (dominant) and diketo- (DK) metribuzin appear as intermediate metabolites in all substrates and were further transformed to desamino-diketo-metribuzin (DADK) which was fully degraded only in compost-biomixture GSBX. Overall, lower amounts of metabolites were accumulated in biomixtures compared to soil stressing the higher depuration efficiency of biobeds.

Degradation of terbuthylazine, difenoconazole and pendimethalin pesticides by selected fungi cultures

Contamination of waters by xenobiotic compounds such as pesticides presents a serious environmental problem with substantial levels of pesticides now contaminating European water resources. The aim of this work was to evaluate the ability of the fungi Fusarium oxysporum, Aspergillus oryzae, Lentinula edodes, Penicillium brevicompactum and Lecanicillium saksenae, for the biodegradation of the pesticides terbuthylazine, difenoconazole and pendimethalin in batch liquid cultures. These pesticides are common soil and water contaminants and terbuthylazine is considered the most persistent triazine herbicide in surface environments.P. brevicompactum and L. saksenae were achieved by enrichment, isolation and screening of fungi capable to metabolize the pesticides studied. The isolates were obtained from two pesticide-primed materials (soil and biomixture).Despite the relatively high persistence of terbuthylazine, the results obtained in this work showed that the fungi species studied have a high capability of biotransformation of this xenobiotic, comparatively the results obtained in other similar studies. The highest removal percentage of terbuthylazine from liquid medium was achieved with A. oryzae (~80%), although the major biodegradation has been reached with P. brevicompactum. The higher ability of P. brevicompactum to metabolize terbuthylazine was presumably acquired through chronic exposure to contamination with the herbicide. L. saksenae could remove 99.5% of the available pendimethalin in batch liquid cultures.L. edodes proved to be a fungus with a high potential for biodegradation of pesticides, especially difenoconazole and pendimethalin.Furthermore, the metabolite desethyl-terbuthylazine was detected in L. edodes liquid culture medium, indicating terbuthylazine biodegradation by this fungus.The fungi strains investigated could prove to be valuable as active pesticide-degrading microorganisms, increasing the efficiency of biopurification systems containing wastewaters contaminated with the xenobiotics studied or compounds with similar intrinsic characteristics.

Effects of Wood Amendments on the Degradation of Terbuthylazine and on Soil Microbial Community Activity in a Clay Loam Soil

The herbicide terbuthylazine is widely used within the EU; however, its frequent detection in surface and groundwater, together with its intrinsic toxicological properties, may pose a risk both for human and environmental health. Organic amendments have recently been proposed as a possible herbicide sorbent in soil, in order to limit herbicide movement from soil to water. The environmental fate of terbuthylazine depends not only in its mobility but also in its persistence. The latter is directly dependent on microbial degradation. For this reason, the effects of pine and oak residues on terbuthylazine soil microbial community functioning and on the potential of this community for terbuthylazine degradation were studied. For this purpose, degradation kinetics, soil dehydrogenase activity and the number of live bacteria were assessed in a clay loam soil treated with terbuthylazine and either amended with pine or oak wood or unamended (sterilised and non-sterilised). At day 65, 85 % of the herbicide applied still persisted in the sterile soil, 73 % in the pine-amended one and 63 % in the oak-amended and unamended ones. Pine residues increased the sorption of terbuthylazine to soil and hampered microbial degradation owing to its high terbuthylazine sorption capacity and a decrease in the bioavailability of the herbicide. On the contrary, in the presence of oak residues, the herbicide sorption did not increase significantly. The overall results confirm the active role of the soil microbial community in terbuthylazine degradation in amended and unamended soils and in a liquid enrichment culture performed using an aliquot of the same soil as the inoculum. In this clay loam soil, in the absence of amendments, the herbicide was found to be quite persistent (t 1/2 > 95 days), while in the enrichment culture, the same natural soil bacterial community was able to halve terbuthylazine in 24 days. The high terbuthylazine persistence in this soil was presumably ascribable to its texture and in particular to the mineralogy of the clay fraction.

Degradation of terbuthylazine, diflufenican and pendimethalin pesticides by Lentinula edodes cultures

Degradation of terbuthylazine, diflufenican and pendimethalin pesticides by Lentinula edodes cultures

Terbuthylazine persistence in an organic amended soil

The aim of this work was to study the effect of the application of a solid waste from olive oil production (alperujo) on the movement and persistence of the herbicide terbuthylazine (N2-tert-butyl-6-chloro-N4-ethyl-1,3,5-triazine-2,4-diamine). An experimental olive grove was divided in two plots: (i) Plot without organic amendment (blank) and (ii) Plot treated with alperujo during 3 years at a rate of 17920 kg of alperujo ha− 1. Terbuthylazine was applied to both plots at a rate of 2 kg ha− 1 a.i. Triplicates from each plot were sampled at 3 depths (0–10, 10–20 and 20–30 cm), air-dried, remains of olive leaves, grass roots, and stones removed and sieved through a 5 mm mesh sieve. Terbuthylazine was extracted with methanol 1:2 weight:volume ratio, the extracts were evaporated to dryness, resuspended in 2 mL of methanol, filtered and anylized by high performance liquid chromatography (HPLC). Higher amounts of terbuthylazine were detected at each sampling depth in plots treated with alperujo. The increase in soil organic matter content upon amendment with alperujo slightly increased sorption, suggesting that other factors beside sorption affect terbuthylazine degradation rate in organic amended soils.