Simazine Residues Research Articles

Leaching of simazine in organic‐amended soils

A laboratory study with a 1×3 factorial design has been conducted to assess the effect of the addition of 10% and 20% w/w of an organic amendment [26% organic carbon (C)] in sorption, degradation and leaching of simazine in a sandy soil (0.66% organic C, 75% sand, 16% clay). Sorption studies have been performed following a batch equilibration procedure and sorption isotherms fitted to Freundlich equation. The Kf increased by a factor of 2.5 and 1.8 with high and low amendment dose, respectively. Simazine treated soils were incubated at ‐33 KPa moisture content and 20°C for 28 days (d). Soils were sampled periodically and simazine residues extracted with methanol. No changes in simazine residues with incubation time were observed for the original unamended soil, whereas calculated half‐lives obtained by fitting simazine dissipation curves in the amended soils to first order kinetics were 123 d for the lower dose and 69 d for the high dose. Mobility was studied in handpacked soil columns under fluctuating saturated/ unsaturated flow conditions. Breakthrough curves were consistent with an inverse relationship between leaching and sorption, with greater mobility of simazine in the untreated sandy soil than in the amended soils. Recoveries of initially applied simazine in leachates after the application of 750 mL of water were 93% for the original soil, 88% for soil amended with the low dose of humic amendment, and 53% for the high dose, which is also consistent with degradation studies. These results indicate that the humic amendment reduces herbicide leaching by promoting sorption and degradation processes.

Persistência e lixiviação do herbicida simazina em solo barrento cultivado com milho

Foram determinadas, em experimento de campo, a persistência e a lixiviação do herbicida simazina na dose de 3 kg/ ha i. a. em um solo podzol vermelho-amarelo de textura barrenta plantado com milho, por meio do monitoramento de seus resíduos, durante um ano após a sua aplicação, em 14 de janeiro de 1992. O experimento foi conduzido na Estação Experimental do Instituto Biológico, Campinas, SP, utilizando-se o método de cromatografia gasosa para a determinação analítica de resíduos. Empregou-se o fatorial 8 X 5, "épocas de amostragem do solo" X "profundidades de amostragem", quatro repetições para os procedimentos experimentais no campo, reduzidas para duas nas de terminações analíticas. Os resultados demonstraram que a maior concentração do herbicida localizou-se na camada superficial do solo (0-10 cm de profundidade), onde persistiu até 360 dias após o tratamento na concentração de 0,08 mg/kg de solo. A curva de persistência do produto, para a profundidade de 010 cm , foi representada por uma equação exponencial do terceiro grau. Foram encontrados resíduos de simazina nas camadas de solo à profundidades de 10 -20, 20 -30 e 30-40 cm até 1 8 3 , 6 5 e 6 5 dias após o tratamento, respectivamente.

PESTICIDE OCCURRENCE IN GROUNDWATER IN TULARE COUNTY, CALIFORNIA

Geographic Information Systems (GIS) and statistical methods were used to identify the major factors affecting pesticide leaching in groundwater from agricultural fields in Tulare County, California. Residues of bromacil, diuron, and simazine increased in groundwater during the 1980s. Bromacil, diuron, and simazine contamination were positively correlated to crop diversity and water demand. Diuron and simazine were positively correlated to groundwater depth and negatively correlated to soil water-holding capacity. DBCP concentration in groundwater was related to the crop coverage. The Goss model was used to examine soil-pesticide interactions and a Pesticide Contamination Index (PCI) was developed. Areas having high leaching potentials were mainly associated with citrus and orchards and coarse-textured sandy soils along the Sierra Nevada foothills, while areas having low leaching potentials were associated with field crops and clay soils of the southwest region. The PCI was largest for DBCP during the 1980s, suggesting that it was the most significant contaminant before 1977 when it was widely used; however, wells were not tested for this pesticide during that period. Twelve years after DBCP was banned, it was still the most significant health risk contaminant. Spatial maps showing the distribution of leaching potentials and soil interactions for these pesticides can provide useful information to regulatory and planning agencies for land use planning and pesticide management.

Microwave assisted solvent extraction (MASE) for the efficient determination of triazines in soil samples with aged residues

The use of microwave-assisted solvent extraction (MASE) as an alternative for conventional solvent extraction procedures for the determination of some triazine herbicides in soil samples has been investigated. In this study MASE method development was focused on the selection of a suitable extraction solvent prior to the instrumental analysis of uncleaned extracts with gas chromatography and nitrogen-specific detection. A mixture of dichloromethane-methanol (90∶10, v/v) yielded recoveries ranging from 89 to 103 (spiked level 200 μg/kg) with RSDs ranging from 2.1 to 5.3%. This solvent mixture is also very convenient for further procedure. The selected MASE procedure was tested by analyzing freshly spiked soil samples and samples with aged residues of atrazine, desethylatrazine, desisopropylatrazine and simazine. The results were compared with those obtained by a conventional liquid extraction method. The comparative study indicated that MASE yields recoveries at least as good as those obtained by the conventional method. Moreover, the MASE procedure provides low solvent consumption in combination with a high sample throughput.

Weed populations in olive groves under non-tillage and conditions of rapid degradation of simazine

Summary In 49 olive tree groves in southern Spain under non-tillage and treated in the autumn with simazine, a total of 315 weed species was identified. However, only eight annual specics reached a moderate mean infestation of infested ficlds. In each field the number of observed species ranged from 4 to 78. The most important annual species that survived simazine treatment were Lolium rigidum, Galium tricornutum and Sherardia arvensis and, locally in a few fields, others such as Amaranthus spp., Conyza spp., Pulicaria paludosa, Sinapis alba. Torilis arvensis and Rumex bucephalophorus. Sedum album, R. bucephalophorus, P. paludosa, Briza maxima and Hypericum perforatum were mainly found in slope soils with high altitude and low carbon content. Cyperus rotundus, Conyza banariensi, Amaranthus blitoides, Galium spurium and Diplotaxis virgata were found at high densities in irrigated fields. Simazine residues recorded 6 months after herbicide application were very low, amounting on average to levels less than 3% of the applied rate. In soil treated with simazine for 7 years. simazine degradation was much faster than in previously untreated soil, particularly at temperatures of 15-25°C.

Liquid Chromatographic Determination of Simazine, Atrazine, and Propazine Residues in Catfish

A liquid chromatographic (LC) method is described for the simultaneous determination of the triazine herbicides, simazine (SIM), atrazine (ATZ), and propazine (PRO) in the 12.5-100 ppb range in catfish. The herbicides are extracted from catfish homogenates with ethyl acetate, followed by solvent partitioning between acetonitrile and petroleum ether and additional cleanup on a C18 cartridge. A Supelcosil LC-18-DB column is used for LC separation, and UV determination is at 220 nm. The isocratic mobile phase is a mixture of methanol, acetonitrile, and water. Mean recoveries from catfish were 88.7, 96.9, and 91.7%; standard deviations were 6.84, 7.78, and 6.26%; and coefficients of variation were 7.72, 8.03, and 6.82% for SIM, ATZ, and PRO, respectively.

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 < 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.

LOW INPUT PEACH PRODUCTION: FIRST-YEAR RESULTS

Three systems of peach production have been established (Flore, et al., 1991, HortScience 26(6):747) utilizing three levels of chemical input: conventional input, moderate level, and low level. The moderate and low levels of chemical input use increasing degrees of IPM. In 1992, data were collected on yield, insect and disease impact on fruit quality, vegetative growth, nitrate and simazine levels in the soil, and insecticide residues in the fruit. The yield per tree was substantially higher in the conventional treatment but this effect could be attributed to an early spring frost, local topography, or the treatment system. The percentage of fruit free from insect and disease damage was highest in the conventional treatment (95.1%), but the low input had a relatively high percentage of fruit free of damage (79.6%). Shoot cold hardiness of one year old shoots was not affected by treatment. Bud survival after a spring frost was greater in the conventional orchards, but topography may have influenced this parameter. Nitrate levels 2 m in the soil and sim-azine residues in the A horizon were not affected by treatment. Lorsban®, Guthion®, and Asana® residues in fruit are currently being analyzed and will be discussed. Additional data collected in 1993 and future years will contribute more information on the use of the low and moderate chemical input treatments on peach production.

Desorption and Bioavailability of Aged Simazine Residues in Soil from a Continuous Corn Field

Journal of Environmental QualityVolume 21, Issue 2 p. 294-294 ErrataFree Access Desorption and Bioavailability of Aged Simazine Residues in Soil from a Continuous Corn Field This article corrects the following: Desorption and Unavailability of Aged Simazine Residues in Soil from a Continuous Corn Field Stephen L. Scribner, Thomas R. Benzing, Shaobai Sun, Stephen A. Boyd, Volume 21Issue 1Journal of Environmental Quality pages: 115-120 First Published online: January 1, 1992 Stephen L. Scribner, Stephen L. ScribnerSearch for more papers by this authorThomas R. Benzing, Thomas R. BenzingSearch for more papers by this authorShaobai Sun, Shaobai SunSearch for more papers by this authorStephen A. Boyd, Stephen A. BoydSearch for more papers by this author Stephen L. Scribner, Stephen L. ScribnerSearch for more papers by this authorThomas R. Benzing, Thomas R. BenzingSearch for more papers by this authorShaobai Sun, Shaobai SunSearch for more papers by this authorStephen A. Boyd, Stephen A. BoydSearch for more papers by this author First published: 01 April 1992 https://doi.org/10.2134/jeq1992.00472425002100020035xCitations: 5AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume21, Issue2April‐June 1992Pages 294-294 RelatedInformation

Desorption and Unavailability of Aged Simazine Residues in Soil from a Continuous Corn Field

AbstractThe sorption/desorption behavior of field weathered (aged) simazine (2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine) residues from a 20‐year continuous corn (Zea mays L.) field was compared to that of 14C‐simazine recently added to the same soil. The apparent sorption coefficients of the aged residues determined from 24‐h and 48‐h desorption experiments were approximately 15 times higher than the sorption coefficients of added simazine. Aged simazine residues were also shown to be biologically unavailable to sugarbeet (Beta vulgaris L.) and to microbial degraders, whereas recently added simazine showed herbicidal damage to sugarbeet and was substantially (ca. 48%) degraded during a 34‐d incubation in soil. Apparently, the process of pesticide aging results in simazine residues that are less bioavailable, as shown by their resistance to plant uptake and microbial degradation, and that desorb slowly into soil solution. The concentration of simazine in water from field soil‐samples (C) was monitored throughout a growing season, and compared to the equilibrium aqueous phase concentration (Cc) predicted from the laboratory determined sorption coefficient (Koc of added 14C‐simazine. The fractional equilibrium values (C/Ce.) were approximately 1 at the time of simazine application in May but fell to 0.05 during July and August. These results show that the concentration of simazine in water contacting field soil is likely to be substantially lower than that predicted from laboratory determined sorption coefficients, except immediately following application.

Desorption and Bioavailability of Aged Simazine Residues in Soil from a Continuous Corn Field

Desorption and Bioavailability of Aged Simazine Residues in Soil from a Continuous Corn Field

Determination of herbicide residues in soil in the presence of persistent organochlorine insecticides

A rapid and reproducible gas-chromatographic method has been developed for determination of residues in soil of some widely used herbicides such as trifluralin, metribuzin, alachlor, acetochlor, metolachlor, pendimethalin, simazine, atrazine, prometryne, in the presence of persistent organochlorine insecticides (p,p-DDT, o,p-DDT, p,p-DDE, alpha-HCH, gamma-HCH, heptachlor). Determination of some herbicides by GC/ECD is difficult since their relative retention times on packed columns usually used for pesticide analysis are equal or close to those of some persistent organochlorine insecticides which can still be found almost everywhere, especially in cultivated soils. A 1.8 m column of 3% OV-225 + 5% SE-52 in a ratio of 1.4:0.9 gave good separation of all herbicides and insecticides mentioned. The influence of 6 solvents and solvent systems applied most frequently for soil extraction of pesticide residues on recovery of the compounds under study was examined. Acetonitrile was the most suitable extractant as it rendered highest residue recoveries and minimal amount of co-extractives. Residues of simazine, atrazine, and prometryne were determined in the same extracts by the use of NP-detector and a column of 5% Carbowax 20M. Recoveries of the compounds under study were in the interval of 86–103% without cleanup and 78–94% when cleanup was carriet out. The method can be used in pesticide monitoring of soil as it offers an opportunity for rapid determination of soil applied herbicides and persistent organochlorine insecticides which are some of the most common pollutants in cultivated soils.

SIMAZINE RESIDUES IN CITRUS ORCHARD SOILS UNDER LONG-TERM CHEMICAL WEED CONTROL

Simazine is a pre-emergent herbicide of low water solubility (5 ppm) that is long-lasting and has high crop selectivity. Simazine residues in a citrus orchard, portions of which have been under chemical weed control for an extended period, were quantified. The orchard is located in the semi-tropical region of South Texas on alluvial Hidalgo sandy clay soil of relatively uniform profile. The orchard investigated had been included in a long-term weed control study lasting 30 years. Three treatments were established based upon the history of the herbicide use. Treatment A had received herbicide applications for 30 years and simazine applications during the last 8 years (22.8 kg·ha-1 total simazine application). Treatment B was mechanically cultivated without herbicides for 28 years and received annual simazine applacations the last 2 years (7.6 kg·ha-1 total). Treatment C was maintained in grass sod and received no herbicide. Soil fractions were taken at 15-cm increments by soil probe to a total depth of 1.5 m. Three probes in each of three replicate plots for each treatment were analyzed. The highest concentration of simazine was found near the surface and decreased with depth. The rate of this decrease was less with treatment A than with B. In the depth range of 15 to 105 cm, treatment A had a greater simazine content than with treatment B. Simazine was detected in some samples below the 120 cm depth.

Measurement of simazine residues in chickpeas, Cicer arietinum, by gas–liquid chromatography

AbstractA method is described for the measurement of simazine [2‐chloro‐4,6‐bis(ethylamino)‐1,3,5‐triazine] residues in chickpeas (Cicer arietinum). Ground chickpea samples were extracted with dichloromethane, followed by clean‐up on alumina. Gas‐liquid chromatography using metribuzin [4‐amino‐ 6‐tert‐butyl‐4,5‐dihydro‐3‐methylthio‐1,2,4‐triazin‐5‐one] as internal standard with thermionic detection was used to quantify simazine residues. The limit of detection was 0.02 mg kg−1 and the recoveries of simazine from chickpea samples (0.1–4 mg kg‐1) averaged 92%.

Persistence and mobility of simazine in some New Zealand soils

Abstract The residual activity and movement of the herbicide simazine was measured in 4 soils varying widely in their physical and chemical characteristics. The levels of simazine remaining in the soil collected from field plots were measured at regular intervals by bioassay with oats (Avena sativa L.), as well as by gas liquid chromatography. Simazine persisted at the 2 kg/ha application rate in phytotoxic amounts in the 0–10 cm depth up to 160 days and > 168 days at the 4 kg/ha rate. Samples collected from the 10–20 cm depth showed that simazine had leached in phytotoxic amounts in only one site and that much of the herbicidal activity remained in the top 10 cm of all soils throughout the study. The chemical residues of simazine disappeared in accordance with first order kinetics. At 2 sites with pH 5.4–5.5, and organic carbon levels of 4.6 and 9.4%, the half-lives were 25 and 32 days respectively. Bioassays suggested that the residual activity was higher at higher pH levels and at lower organic matter ...

The comparative behaviour of simazine and terbacil in soils

SummaryAdsorption of simazine (2‐chloro‐4,6‐bisethyl‐amino‐1,3,5‐triazine) was 2.2–4 times greater than that of terbacil (5‐chloro‐6‐methyl‐3‐t‐butyl‐uracil) in the same soils and adsorption of both herbicides was 2–4 times greater in the topsoils than subsoils. Adsorption was inversely correlated with herbicide movement in a thick‐layer chromatography system. One year after application of 3 kg/ha to field plots, simazine residues were highest near the soil surface, whereas terbacil residues increased with soil depth in the sandy and sandy loam soils. Total residues recovered from the upper 25 cm of soils was 5% or less of the simazine originally applied, and 10% or less of the applied terbacil. In an oat seedling bio‐assay, the GR50 values were generally 1.5–3 times higher for simazine than for terbacil in the same soils.

Residues of Simazine and Hydroxysimazine in an Orchard Soil

Simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] was applied annually at 4.5 kg/ha to uncultivated sandy loam of peach (Prunus persicaBatsch) for 7 yr (orchard A) and 9 yr (orchard B). Simazine and the metabolite, hydroxysimazine [2-hydroxy-4,6-bis (ethylamino)-s-triazine] as determined by gas chromatography (GC) persisted for 40 and 28 months in soil of orchard A and B, respectively. However, no progressive accumulation of either compound in large quantities occurred from repeated annual applications of simazine to the orchard soils. No metabolites other than hydroxysimazine were detected. Hydroxysimazine was degraded more slowly than simazine and the residue levels of hydroxysimazine were at least 40 times those of simazine 40 months and 28 months after the final application in orchard A and B, respectively. Both simazine and hydroxysimazine residues were detected in the upper 30 cm of the soil profile.

Modification of the rheotropic response of rainbow trout ( Salmo gairdneri) by sublethal doses of the aquatic herbicides diquat and simazine

The rheotaxis and swimming speeds of rainbow trout in response to a water current simulated by moving a striped background past the fish were observed following 24-h exposures to field application concentrations of the herbicides diquat, simazine and their commercial formulations. Fish tissues were subsequently analysed to assess the extent of uptake of the herbicides. Toxicological modification of rheotaxis and swimming speeds was observed in fish exposed to diquat and its formulation Reglone A® resulting in an increased incidence of downstream drift. Simazine residues in fish increased in proportion to treatment levels whereas diquat residues in fish levelled off with increasing treatment levels. The toxicological modification of rheotropism is presented as a sensitive bioassay to assess sublethal effects of biocides.

Simazine Residue Levels in Irrigation Water after Ditchbank Application for Weed Control

AbstractA field study was conducted to determine the amount of simazine [2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine] likely to be found in irrigation water after ditchbank treatment for weed control. Resulting data are useful in evaluating the potential impact of simazine on crops irrigated from sprayed canals. Canals were selected in California, Colorado, and Washington for the application of simazine to both watered and dewatered sites at rates of 2.25 to 7.43 kg/ha. Simazine levels in flowing canal water immediately after herbicide application did not exceed 60 µg/liter. In first‐flow samples collected in the spring from the sites that were dewatered at application, simazine levels peaked at about 250 µg/liter within the treated section but decreased rapidly to <5 µg/liter.

The effect of age on the availability of linuron and simazine residues in soil

Summary:Residues of linuron and simazine were measured by both bioassay and gas‐chromatographic methods in soil from field plots that had been treated either 20 weeks (both compounds). 41/2 years (linuron) or 51/2 years (simazine) previously. There were no significant differences between the results obtained with the two methods; therefore the relationship between extractable herbicide and that available to plants was independent of the age of the residue. Hence‘bound’residues, if they existed in these plots, had no phytocidal significance.