Triazine Herbicides In Soil Research Articles

Adsorption Behavior and Residue Degradation of Triazine Herbicides in Soil Amended with Rice Straw Biochar

The removal of or decrease in pesticide residues in soil has attracted considerable attention, due to the serious pollution of pesticides in soil. The purpose of the study was to explore the adsorption behavior of biochar on pesticides and the impact on the degradation of pesticide residues in soil, providing a basis for the remediation of soil by biochar. Biochars were prepared via pyrolysis of rice straw at a high temperature (300 °C, 400 °C, 500 °C, 600 °C). The individual and competitive adsorption of three triazine herbicides, prometryn, atrazine, and simazine, on biochar was investigated, and the degradation of the herbicide residues in biochar-added soil was determined. The selected herbicides presented similar adsorption characteristics to rice straw biochar, and the amount of herbicides adsorbed increased with higher preparation temperature and the amount of biochar. The rice straw biochar adsorbed the studied herbicides simultaneously, and the adsorption amount decreased as follows: simazine > atrazine > prometryn. The competition adsorption of the selected herbicides on the biochar presented a lower adsorption affinity than that when they are adsorbed individually. The adsorption isotherm was best fitted by the Freundlich model. The half-lives of prometryn, atrazine, and simazine were 9.8~12.6 d, 5.2~8.1 d, and 3.7~5.6 d, respectively. Biochar addition increased the degradation of the evaluated herbicides in soil. The rice straw biochar could be the potential sorbents that can be implemented for the removal of pesticides.

Promene u rastu Pseudomonas sp. CY u prisustvu atrazina

Microbial degradation, compared with many other degradation processes, is the most important pathway for the depletion of triazine herbicides in soil. The aim of this study was to determine the growth potential of Pseudomonas sp. CY in the presence of atrazine and additional carbon (sodium citrate) and nitrogen (ammonium-nitrate) sources. The experiment was performed with five treatments: i) 100 mg/L atrazine (control); ii) One hundred mg/L atrazine + sodium citrate (0.3 %, w/v); iii) One hundred mg/L atrazine + sodium citrate (0.3 %, w/v) + ammonium nitrate (0.6 %, w/v); iv) Atrazine (300 mg/L) + sodium citrate (0.3 %, w/v) and v) Atrazine (500 mg/L) + sodium citrate (0.3 %, w/v). The bacterial count was determined after incubation (7 days at 30°C) using the agar plate method, while atrazine degradation was determined by measuring the optical density at 221 nm. Pseudomonas sp. CY can partially utilize atrazine as the sole source of carbon and energy. The highest values of the bacterial count were determined at the highest initial atrazine concentrations; however, bacterial growth was not detected in these treatments. A significant impact of citrate on bacterial growth and atrazine degradation was observed, while the addition of nitrate decreased the atrazine degradation rate. This study confirmed that Pseudomonas sp. CY can be used as a prominent candidate for the remediation of atrazine-affected environments.

Dynamic Microwave-Assisted Micelle Extraction Coupled with Cloud Point Preconcentration for the Determination of Triazine Herbicides in Soil.

A green and simple method, dynamic microwave-assisted micelle extraction coupled with cloud point preconcentration, was developed for the determination of triazine herbicides in soil samples. The method has the advantages of those two extraction procedures, which could eliminate the interferences from complex soil samples greatly. Non-ionic surfactant Triton X-114 aqueous solution used as extraction solvent was continuously pumped into soil samples. The resulting extract was heated and centrifuged in the presence of NaCl. After centrifugation, the analytes were enriched into the surfactant-rich phase. No filtration or cleaning steps were required. Several key parameters were investigated. The Box-Behnken design was applied to optimize the experimental factors involved in the dynamic microwave-assisted micelle extraction. Good linearity was observed in the range of 1.00-250.00μgkg-1. The limits of detection were ranged between 0.26 and 1.71μgkg-1. The recoveries of analytes ranged from 80.3 to 98.3% with the relative standard deviations ranging from 1.1 to 6.6%.

Imidazolinone and triazine herbicides in soils in relation to the complexes formed with Cu(II) ions

Imidazolinone and triazine herbicides are used in many countries and may have a great impact on metal biocycles in soil. This article deals with the dynamics of imidazolinone and triazine herbicides in soils related to the formation of complexes with Cu(II) ions, which can be very stable. The stability constants of the complexes formed by five imidazolinone herbicides and ten triazine herbicides with Cu(II) ions are determined by means of fast, easy, and inexpensive measurements performed by ultraviolet–visible spectroscopy, for imidazolinones, and voltammetry (cyclic and differential pulse), for triazines. Because of the occurrence of dissociation reactions, the determinations were performed at three pH values for imidazolinones and at one pH value for triazines. In aqueous solutions of 5 < pH < 10 (corresponding to the majority of soils of agricultural use), the herbicides form very stable complexes with the Cu(II) ions, the complexes being integrated by two ligands (herbicides) and one copper ion. In conclusion, crops treated with such herbicides in conjunction with Cu(II) salts experience a decrease in its persistence and effectiveness. In addition, the herbicides and the copper ions may pass to the phreatic layer of the soil, increasing the chance of pollution.

Assessment of Triazine Herbicides in Soil by Microwave-assisted Extraction Followed by Gas Chromatography Coupled to Mass Spectrometry Detection

Assessment of Triazine Herbicides in Soil by Microwave-assisted Extraction Followed by Gas Chromatography Coupled to Mass Spectrometry Detection

Biomonitoring of Human Exposure to Triazine Herbicides

Triazine herbicides are very common and only 0.1 % reach the target pests, while the rest moves into other environmental compartments. Their fate in the environment depends on their movement through the air, water, and soil and on the rate of their degradation or transformation. Triazine compounds may be transformed by water, microorganisms, and sunlight. Widespread use and persistence of triazine herbicides in soil has resulted in contamination of surface, drinking, and even rain water with parent compounds and degradation products, posing a risk to the general population.The metabolism and effects of triazine herbicides have been studied in experimental animals and in experiments in vitro. There are only a few studies of their metabolism and excretion in humans. Agricultural and manufacturing workers are exposed to triazines during application and production. Human exposure is monitored by determining parent compounds and their metabolites in urine. Due to the low concentrations of urinary metabolites in occupationally exposed persons, very sensitive analytical methods are required. This paper describes the structure and properties of symmetric triazine herbicides, their metabolism, and effects in humans and animals and the levels of these compounds in the urine of occupationally exposed persons.

Quantification of triazine herbicides in soil by microwave-assisted extraction and high-performance liquid chromatography

A method for the determination of herbicides residues, triazine (atrazine, metribuzin, ametryn, and terbutryn), in soil samples with high-performance liquid chromatography (HPLC)-UV detection is described. The proposed method is based on microwave-assisted extraction (MAE) of soil samples for 4 min at 80% of 850-W magnetron outputs in the presence of mixture of solvents (methanol/acetonitrile/ethylacetate). Related important factors influencing the MAE efficiency, such as the solvent type and volume, irradiation energy, and time, were optimized in detail. Calibration curve ranges established using HPLC for metribuzin, atrazine, ametryn, and terbutryn are 1.0-19.0, 0.9-18.0, 0.6-11.0, and 0.7-11.0 µg mL( -1), respectively. The limits of detection of metribuzin, atrazine, ametryn, and terbutryn are 0.30, 0.24, 0.16, and 0.20 µg mL( -1) while limits of quantification are 1.0, 0.80, 0.50, and 0.60 µg mL( -1), respectively. A Plackett-Burman factorial design was used as a screening method in order to select the variables that influence MAE extraction. The recoveries of the method at three different spiked levels were assessed by analyzing real soil samples and were found to be in the range of 83.33 ± 0.12-96.33 ± 0.23 with good precision (<8%).

Effect of organic matter content in the trace analysis of triazines in various types of soils with GC-NPD

Recent work demonstrated that the combination of microwave assisted solvent extraction (MASE) and capillary gas chromatography with selective nitrogen detection (GC-NPD) is a viable approach for the efficient determination of triazine herbicides in soils. However, for soils with a high organic matter content or the injection of more concentrated extracts to obtain lower LOD's the performance of gas chromatographic analysis of uncleaned extracts is hampered. This results in both a decrease of the chromatographic response of analytes and a decrease in the life time of the column due to coextracted matrix substances. The effect of various types of soils on the chromatographic analysis of triazine herbicides was studied. It appeared that for the investigated samples with an organic matter content below 5% processing of uncleaned extracts is possible. Samples with a higher organic matter content required a cleanup step. A rapid procedure on 100 mg silica cartridges has been developed using solvents compatible with the MASE extracts and the instrumental analysis. Beside the testing with different standard soils, about 120 samples of an ongoing monitoring program involving three different types of soil (organic matter content: 3–37%) were analysed. The selected compounds atrazine, desethylatrazine, desisopropyl-atrazine and simazine could be assayed in the various soil types to a level of at least 2 μg kg−1. For soil samples with a high organic matter content (>5%), the rapid cleanup procedure allowed the trace analysis of the triazines and considerably increased the life time of the capillary column. Recoveries at levels from 2 to 50 μg kg−1 ranged from 70 to 100% with RSDs ranging from 5.1 to 9.5%. Confirmation of positive samples was carried out by gas chromatography mass spectrometry.

Movement and persistence of triazine herbicides in soils used for lupin production in Western-Australia - Field-measurements and interpretations with the aid of a simulation-model

Movement and persistence of simazine and atrazine in an acid sand were measured in 1989 at a field site that received 76-105 mm of rainfall during 100 days after herbicide application. Three environments were created: (i) warm and wet (early herbicide application of 100 mg m-2 on 28 May); (ii) cool and dry (later herbicide application of 100 mg m-2 on 24 June); (iii) cool, dry and high pH (the later herbicide application after the surface pH had been raised from 4 . 8 to 6 . 4 by the application of 150 g m-2 CaCO3 42 days earlier). The soil profile was sampled for herbicide residues and soil water at six depths on five occasions during 100 days after herbicide application. Rainfall, pan evaporation, and soil and air temperatures were measured throughout the experiment. Soil temperatures at 13 mm ranged from 11 to 41�C (daily minimum and maximum). Most of the herbicide remained in the surface 25 mm of soil and after 100 days about 25% of that applied remained in the soil profile in the acid soils and about 40% remained in the soils treated with CaCO3. Despite eight, or nine, leaching rains that a simulation model estimated would have wetted the profile to 300 mm, residues &lt; 2 mg m-2 were found in the 150-200 mm layer and in the high pH treatment only. A simulation model gave good agreement with observed losses of simazine residues in soil maintained at field capacity and buried within the soil profile. However, the simulation model underestimated residue losses in the soil profile and indicated that processes other than chemical hydrolysis were involved in the degradation of herbicide in the surface 25 mm of soil. Weed control reliant on persistent residues would be prolonged if the herbicide is applied near the sowing date of the lupin crop and incorporated below the surface 25 mm of soil by the method of sowing.

Corrigenda - Adsorption and degradation of triazine herbicides in soils used for lupin production in Western-Australia - Laboratory studies and a simulation model

Most lupins (Lupinus angustifolius L. and L. albus L.) grown in Western Australia are sown with simazine, and some with atrazine, to give persistent control of a broad spectrum of weeds. Rates of application are adjusted for soil types yet there can be ineffective weed control and crop damage. The kinetics of degradation in four soils was studied in the laboratory to determine how it varied between soils and was modified by soil temperature, pH, moisture and gamma irradiation. The time for half the herbicide to be lost from the soils (HL) varied from 42 to 110 days at 20�C and -0.08 MPa water potential. Loss was rapid in the first day of incubation and subsequent losses were described precisely by first-order functions. However, the first-order half-lives (t1/2) were 3-21 days greater than the corresponding HLs, because the first-day losses were unaccounted for by the first-order functions. Gamma irradiation had no influence on degradation kinetics which supported chemical hydrolysis as the mechanism of degradation. The t1/2 values were correlated positively with the proportion of applied herbicide that was adsorbed by the soils (PAd). Atrazine was more persistent than simazine and had higher PAd values. The PAd values increased with soil pH, organic matter and clay content. The t1/2 values decreased exponentially with temperatures from 28 to 9-degrees-C, and decreased with soil water potentials from -0.08 to -1.50 MPa for a loamy sand at a near-neutral pH. A computer simulation model gave good agreement with observed residue decays and showed that the initially rapid losses from the soils could be explained by high rates of hydrolysis when all the applied herbicide was in the soil solution and, consequently, herbicide concentrations were high (87-100 mM). Rapid losses of the triazines in the field are likely in warm, acidic soils-particularly if the herbicide concentrations in the soil solution are high for reasons of limited vertical distribution of the applied herbicides through the soil profile.

Adsorption and degradation of triazine herbicides in soils used for lupin production in Western-Australia - Laboratory studies and a simulation model

Most lupins (Lupinus angustifolius L. and L. albus L.) grown in Western Australia are sown with simazine, and some with atrazine, to give persistent control of a broad spectrum of weeds. Rates of application are adjusted for soil types yet there can be ineffective weed control and crop damage. The kinetics of degradation in four soils was studied in the laboratory to determine how it varied between soils and was modified by soil temperature, pH, moisture and gamma irradiation. The time for half the herbicide to be lost from the soils (HL) varied from 42 to 110 days at 20�C and -0.08 MPa water potential. Loss was rapid in the first day of incubation and subsequent losses were described precisely by first-order functions. However, the first-order half-lives (t1/2) were 3-21 days greater than the corresponding HLs, because the first-day losses were unaccounted for by the first-order functions. Gamma irradiation had no influence on degradation kinetics which supported chemical hydrolysis as the mechanism of degradation. The t1/2 values were correlated positively with the proportion of applied herbicide that was adsorbed by the soils (PAd). Atrazine was more persistent than simazine and had higher PAd values. The PAd values increased with soil pH, organic matter and clay content. The t1/2 values decreased exponentially with temperatures from 28 to 9-degrees-C, and decreased with soil water potentials from -0.08 to -1.50 MPa for a loamy sand at a near-neutral pH. A computer simulation model gave good agreement with observed residue decays and showed that the initially rapid losses from the soils could be explained by high rates of hydrolysis when all the applied herbicide was in the soil solution and, consequently, herbicide concentrations were high (87-100 mM). Rapid losses of the triazines in the field are likely in warm, acidic soils-particularly if the herbicide concentrations in the soil solution are high for reasons of limited vertical distribution of the applied herbicides through the soil profile.

Residue analysis of triazine herbicides in soil: Comparison of a capillary gas chromatographic and a high-performance liquid chromatographic method

Two methods for the determination of triazines in soil were developed and compared. After extraction of the residues with methanol and clean-up by gel permeation chromatography, the samples evaporated were analysed for triazines by splitless capillary gas-chromatography with NP-detector (GC-NPD) and microbore high performance liquid chromatography with UV detector (HPLC-UV) at 222 nm. Both methods gave similar results. The microbore HPLC method was suitable for the analysis of a number of triazines at 10 ppb whereas capillary GC method was used for the analysis of triazines at 5 ppb. Satisfactory average recoveries for the two methods were obtained at 80 ppb and 20 ppb, respectively.

Detection of triazine herbicides in soil by a Hill-reaction inhibition technique after thin-layer chromatography

Detection of triazine herbicides in soil by a Hill-reaction inhibition technique after thin-layer chromatography

Automated Method for Extraction, Cleanup, and Gas Chromatographic Determination of Triazine Herbicides in Soil

Abstract Complete automation of extraction, cleanup, and GLC determination of residue analysis of some important triazine herbicides in soils has been achieved. Manually sieved soil samples are continuously delivered to the system, which presents cleaned up extracts to an automated GLC injection system. Peak areas are calculated by a digital electronic integrator. The output of the integrator is connected to a teletype printer which generates both printed hard copy and a punched paper tape in standard ASCII code. This information is fed by a punchtape reader into a programmed Wang 700 desktop computer. Final analysis reports are printed by an attached typewriter. The system allows a 4-fold output of analytical results with half the personnel compared to manual analysis.

Quantitative determination of triazine herbicides in soils by bioassay.

Man in his efforts to achieve a better understanding of the world around him has continually faced the necessity of finding suitable techniques of study. In many instances, he has utilized the responses of living organisms to gain the desired knowledge through biological assay methods. According to Finney (1947), “The term biological assay in its widest sense should be understood to mean the measurement of the potency of any stimulus, physical, chemical or biological, physiological or psychological, by means of the reactions which it produces in living matter.” A substantial portion of present-day research involves, under this definition, the use of the biological assay. The purpose of this review is to consider the use of bioassays specifically for the quantitative determination of triazine herbicides in soil.

Quantitative determination of triazine herbicides in soils by chemical analysis.

Reliable methods for the chemical analysis of soils for the presence of triazine herbicide are of great importance in determining their persistence in the soil. A large amount of material has been published about the determination of residues in a variety of kinds of samples. Although all of the techniques reported have not been applied to the analysis of soils, they could be. Therefore, this discussion will attempt to review the literature in regard to the broader aspects of the determination of triazine residues but the emphasis will be on methods which are applicable to the analysis of weathered soil samples having residues in amounts that would arise from use of triazine under normal agricultural practice. There are no practical analytical methods available for the analyses of soil for hydroxy-triazines or other degradation products which have sufficient sensitivity or which can be applied to many types of soils. Therefore this report will be limited to the determination of unchanged triazines. The s-triazines generally referred to are those of present commercial importance: atrazine, simazine, propazine, ametryne, prometryne, and prometone.

The thin-layer chromatographic determination of triazine herbicides in soil and water

The thin-layer chromatographic determination of triazine herbicides in soil and water