Photodegradation of the Herbicide Imazethapyr in Aqueous Solution: Effects of Wavelength, pH, and Natural Organic Matter (NOM) and Analysis of Photoproducts

Espy, Ryan; Pelton, Emily; Opseth, Annie; Kasprisin, Jonathan; Nienow, Amanda M.

doi:10.1021/jf200573g

Cited by 40 publications

(33 citation statements)

References 29 publications

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“…The lower dry matter of sorghum at 135 and 150 DAA, when applied to the commercial mixture of imazethapyr and imazapic (Figure 1), is due to the low degradation of the photolytic decomposition (Wang et al, 2006;Espy et al, 2011).…”

Section: Haplic Plinthosol (Fx)mentioning

confidence: 99%

Persistence of Imidazolinones in Soils Under a Clearfield System of Rice Cultivation

et al. 2016

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-The commercial mixture of imazethapyr and imazapic herbicides has been used for the control of red rice and several other species of weeds found in rice crops; this system called Clearfield. However, its use may limit the succession of non-tolerant crops for long residual activity. The research objective with this work was to determine the persistence of imazethapyr, imazapic and their mixture in three soils in the Brazilian state of Tocantins. Three experiments were conducted in a completely randomized design with four replications, each corresponding to the evaluated soil (Haplic Plinthosol (FX), red-yellow Latosol (LVA) and Haplic Gleysol (GX)). The treatments were arranged in a split plot design, with the allocated plots herbicides (imazethapyr and imazapic alone and commercial mixture) and the plots allocated the 11 evaluation times (1, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150 days after treatment (DAT)), and a control without application. Contacted up long residual effect of imazethapyr and commercial mixture of imazethapyr and imazapic, regardless of assessed soil. After 150 days of applying herbicides or the commercial mixture, their residues in the soil also inhibited approximately 94% of the mass of the dry matter accumulation of the indicator plants. When imazapic was applied alone, there was a higher dry matter accumulation of the indicator plants, indicating less residual effect of this herbicide in the soil and this was attributed to the lower dose of this herbicide applied. The attributes of the soil pH, texture and iron oxides were what most affected the persistence of the herbicides. It can be concluded that the persistence of imazethapyr and imazapic is too long in the Brazilian state of Tocantins soils and the use of these herbicides in the region should be avoided due to the high risk of the occurrence of carryover,or be well planned, as land use in rotation for susceptible crops. (1, 15, 30, 45, 60, 75, 90, 105, 120, 135 Keywords

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Section: Haplic Plinthosol (Fx)mentioning

confidence: 99%

Persistence of Imidazolinones in Soils Under a Clearfield System of Rice Cultivation

et al. 2016

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“…Imazapyr and imazapic herbicides were more rapidly degraded in solution compared to on soil surface (Table 1 and Table 2). However, the photolysis rate of imidazolinone herbicides in actual water samples might be slower due to the presence of light screening compounds such as humic acid and natural organic matter (NOM) [3,26].…”

Section: Results and Discussion Photolysis Of Imidazolinone Herbicidementioning

confidence: 99%

Degradation of Imazapyr and Imazapic in Aqueous Solutions and Soil Under Direct Sunlight

Norashikin

Hussain

Hassan

et al. 2017

MJAS

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Photolytic degradation of imazapyr and imazapic in aqueous solutions (pH 3, 7 and 9) and soil under direct sunlight were studied. A total of 0.1 mL of aqueous solutions containing herbicides were collected at 0, 1, 2 and 3 days and were directly analyzed using high performance liquid chromatography equipped with ultraviolet detector (HPLC-UV) without further clean-up process. Soils that were treated with herbicides were sampled at seven different days (0, 1, 5, 10, 16, 23 and 30). The photolytic results showed that imazapyr and imazapic degraded faster in solutions compared to soils (> 90%). Photolysis of imidazolinone herbicides became more effective as the pH value increased. The half-lives for imazapyr and imazapic degradation on soil surface under sunlight were calculated at 126 days and 85.56 days, respectively. Low degradation of imazapyr and imazapic in soil becomes a concern since it may contribute to the persistency of imidazolinone herbicides in this media. The use of these herbicides should be planned well to reduce the risk of herbicides leaching into groundwater and posing risk to non-target crops and organism.Keywords: photolysis, imazapyr, imazapic, aqueous solutions, soil Abstrak Kajian degradasi fotolitik bagi imazapyr dan imazapic dalam larutan akueus (pH 3, 7 dan 9) dan tanah di bawah cahaya matahari telah dijalankan. Sebanyak 0.1 mL cecair larutan yang mengandungi racun rumpai telah diambil pada hari 0, 1, 2 dan 3 dan terus dianalisis menggunakan kromatografi cecair berprestasi tinggi dengan pengesan ultra-ungu (HPLC-UV) tanpa melalui sebarang proses pembersihan. Tanah yang telah dicampurkan dengan racun rumpai telah disampelkan pada tujuh hari yang berbeza (0, 1, 5, 10, 16, 23 dan 30). Keputusan fotolitik menunjukkan imazapyr dan imazapic lebih cepat terurai di dalam cecair berbanding dengan tanah (>90%). Fotolisis racun rumpai imidazolinon adalah lebih berkesan apabila pH meningkat. Jangka masa separuh hayat untuk imazapyr dan imazapic terurai di permukaan tanah di bawah cahaya matahari masing-masing adalah 126 dan 85.56 hari. Degradasi rendah bagi imazapyr dan imazapic dalam tanah telah menjadi suatu kebimbangan kerana ia boleh menyumbang kepada pengekalan racun rumpai imidazolinon di dalam media ini. Penggunaan racun rumpai ini perlu dirancang dengan sebaiknya bagi mengurangkan risiko untuk racun larut terlesap ke dalam air bawah tanah dan menimbulkan risiko kepada tanaman dan organisma yang bukan sasarannya.

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“…On the other hand, soil characteristics may also exacerbate this scenario. For example, large amounts of organic matter causing greater adsorption of imazethapyr by the soil, together with high rainfall, might allow a percentage of the herbicide to run off into surface waters (Espy et al 2011). Besides, it was recently reported that imazethapyr reduces both the microbial biomass and microbial community structure in soils and shows inhibitory effects on many enzymes, such as dehydrogenase, phosphatase, protease, and catalase (Zhang et al 2010).…”

Section: Resultsmentioning

confidence: 99%

“…So, this chemical has been detected in groundwater supplies and surface water courses at concentrations of 0.369 and 0.69 μg L −1 , respectively (Battaglin et al 2000;Espy et al 2011). However, these concentrations in water supplies are lower than the lethal dose 50 (LD50) values obtained in rats by the oral route (LD50>5, 000 mg/kg), indicating that imazethapyr is unlikely to present acute hazard in normal use (WHO 2005).…”

Section: Introductionmentioning

confidence: 99%

Phytotoxicity and genotoxicity assessment of imazethapyr herbicide using a battery of bioassays

Magdaleno

Gavensky

Fassiano

et al. 2015

Environ Sci Pollut Res

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The imazethapyr herbicide (formulation Verosil(®)) was evaluated for phytotoxicity and genotoxicity using a battery of bioassays: (1) the growth inhibition of the green alga Pseudokirchneriella subcapitata, (2) the root growth and germination of the higher plant Lactuca sativa, (3) the genetic damage using the Salmonella/microsome test, and (4) the aneugenic and clastogenic effects on Allium cepa. The Verosil(®) formulation was highly toxic to the non-target green alga (median effective concentration (EC50) = 1.05 ± 0.05 mg active ingredient (a.i.) L(-1)), and concentrations above 10 mg a.i. L(-1) inhibited root elongation in lettuce: relative growth index (RGI) between 0.28 ± 0.01 and 0.66 ± 0.10. No genotoxic effect was observed in S almonella typhimurium at 100 mg a.i. L(-1), either with or without the microsomal fraction. However, significant differences in the frequency of chromosomal aberrations in anaphases and telophases (bridges, chromosome fragments, and vagrants) were observed in A. cepa at concentrations between 0.01 and 1 mg a.i. L(-1) with respect to the control. The frequencies of micronuclei showed significant differences with respect to the control at concentrations between 0.001 and 0.1 mg a.i. L(-1). A very high mitotic index (MI = 93.8 ± 5.8) was observed associated with a high number of cells in the prophase stage at 100 mg a.i. L(-1), indicating cytotoxicity. These results showed that imazethapyr is toxic to the non-target populations in both aquatic and terrestrial ecosystems. This herbicide might also exert clastogenic and aneugenic mitotic damage in higher plants. Therefore, the imazethapyr formulation may constitute an environmental risk to plants.

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Photodegradation of the Herbicide Imazethapyr in Aqueous Solution: Effects of Wavelength, pH, and Natural Organic Matter (NOM) and Analysis of Photoproducts

Cited by 40 publications

References 29 publications

Persistence of Imidazolinones in Soils Under a Clearfield System of Rice Cultivation

Persistence of Imidazolinones in Soils Under a Clearfield System of Rice Cultivation

Degradation of Imazapyr and Imazapic in Aqueous Solutions and Soil Under Direct Sunlight

Phytotoxicity and genotoxicity assessment of imazethapyr herbicide using a battery of bioassays

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