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Propachlor is a pesticide commonly used in the chloroacetanilide herbicide group. Propachlor contamination occurs in groundwater resources and soil sources. Therefore removal and also the determination of trace amounts of propachlor is a very important issue. Molecularly imprinted polymers (MIPS) are preferred for their advantages such as high affinity, strength, and selectivity in pesticide removal and determination. In this study, MIP embedded cryogel was synthesized for selective adsorption and removal of propachlor. MIP synthesis was performed using the template molecule propachlor, functional monomer methacrylic acid, crosslinker ethylene glycol dimethacrylate (EDGMA), solvent hexadecane and 2,2-azo-bis-isobutyronitrile (AIBN) as the initiator. Cryogels are a good alternative for separation and purification because of their advantageous properties such as short diffusion, low pressure and adsorption and elution in a short time. The structure of MIP was determined using scanning electron microscopy (SEM), Elemental analyze and Fourier transform infrared spectroscopy (FT-IR), and the structure of MIP embedded cryogel was determined using scanning electron microscopy (SEM). The highest adsorption capacity for MIP was 5.58 mg g-1 at pH 5. The highest adsorption capacity for MIP embedded cryogel was found to be 14.38 mg g-1. MIP embedded cryogel were used for selective adsorption and desorption of propachlor in environmental samples. The concentration of propachlor in environmental samples was analyzed by high-performance liquid chromatography (HPLC).

Supramolekuler cozuculer (SUPRASs), amfifillerin kendiliginden bir birlesme prosesi ile meydana getirdigi nano yapili sivilardir ve ornek hazirlama basamaginda daha cevre dostu olmalari nedeniyle molekuler organik cozuculere bir alternatif olustururlar. Bu calismada, toprak orneklerindeki propaklor ve prometrin herbisitlerinin mikroekstraksiyonu icin SUPRAS esasli bir analitik metot onerilmektedir. Onerilen metot, 300 mg toprak numunesinin 300 µL SUPRAS ile 8 dakika boyunca vorteks ile karistirilmasini, ardindan faz ayrimi icin santrifujlemeyi ve ultraviyole dedektorlu sivi kromatografisiyle SUPRAS fazinin dogrudan analizini icermektedir. Optimize edilen ekstraksiyon kosullarinda, herbisitler icin ekstraksiyon verimleri % 81 ile % 87 arasinda degisim gostermistir. Metot algilama limitleri, propaklor ve prometrin icin sirasiyla 0.07 µg/g ve 0.01 µg/g olarak bulunmustur. Herbisitler icin bulunan bagil standart sapma degerleri gun-ici ve gunler-arasi tekrarlanabilirlik olarak sirasiyla % 8.8 ve % 12.1’den daha dusuk bulunmustur. Ilgili herbisitlerin Zonguldak bolgesinden toplanan toprak orneklerinden mikroekstraksiyonu verimli bir sekilde yapilmistir. Standart madde ilavesi yapilan toprak ornekleri icin elde edilen geri kazanim degerleri %80 ile %1 08 arasinda degisim gostermistir.

Two field experimental trials were carried out in central Italy, in 2005 and 2006, on biomass sorghum [Sorghum bicolor (L.) Moench] in order to assess weed control efficacy and selectivity to the crop of some pre- and post-emergence herbicides applied at different doses and in different mixtures. All herbicides showed good selectivity to the crop, although postemergence treatments showed higher transitory phytotoxicity effects than pre-emergence treatments, especially when high temperatures occurred after treatments, decreasing the selectivity of leaf herbicides (i.e. MCPA, 2,4-D, bromoxynil and dicamba). Considering pre-emergence applications, terbuthylazine alone against broadleaves or in mixtures at low doses with s-metolachlor against mixed infestations (grasses + broadleaves), seemed to be the best options to obtain a good selectivity to the sorghum and a high weed control level. Aclonifen showed some limits in terms of weed spectrum and could be recommended only against simplified broadleaf weed infestations without the presence of less susceptible weeds, like Amaranthus retroflexus, Portulaca oleracea and Solanum nigrum. Propachlor seemed not to be advisable due to the low efficacy against all the major broadleaf warmseason weed species in the Mediterranean areas. Considering post-emergence applications, all treatments gave quite similar results in terms of weed control, although, the mixture of terbuthylazine + bromoxynil seemed to be the best option due to bromoxinil’s higher efficacy than other foliar herbicides, such as MCPA, 2,4-D and dicamba, which can increase the efficacy of terbuthylazine alone especially under dry weather conditions. There were no significant differences in sorghum biomass between herbicide treatments, although, the more selective pre-emergence treatments showed, on average, a higher biomass yield value than the less selective post-emergence treatments. For these reasons, biomass values seemed to be more related to herbicide selectivity than to herbicide efficacy, especially in cases of scarce competitiveness of weed flora.

ΔΕΝ ΔΙΑΤΙΘΕΤΑΙ ΠΕΡΙΛΗΨΗ, The main objective of the present research was to determine the concentrations of the selected pesticides in muscle, liver and skin of common carp. Fish were sampled in two different seasons from fish pond which received previously treated slaughterhouse wastewater. Pesticides including etridiazole, chloroneb, trifluralin, propachlor, chlorothalonil, hexa-chlorocyclopentadiene, atrazine, simazine, alachlor, metribuzin, metolachlor, DCPA, cyanazine, chlorobenzilate, endrin aldehyde, cis permethrin and trans permethrin were determined by using a GS-MS method. Many of pesticides were not determined or determined in low concentrations. Propachlor was found in muscle, skin and liver. The recommended acceptable daily intake was higher in comparison with the estimated daily intake for examined pesticides via fish reared in treated slaughterhouse wastewater. It is very important to maintain the safety of the fresh fish produced in wastewater in order to ensure food safety and avoid health problems in humans.

A fast and efficient method was developed and validated for the determination of pesticides in mangos, which uses the QuEChERS citrate and gas chromatography–mass spectrometry (GC–MS) techniques. A detailed statistical analysis was performed to study the matrix effect. The calibration model using the method of weighted least squares is used in cases, where heteroscedasticity is observed. The matrix effect was observed for most studied compounds using analytical curves based on a spiked matrix. The limits of detection were 0.0025–0.01 mg kg−1, and the limits of quantification (LOQ) were 0.008–0.03 mg kg−1. The LOQ values were minor or equal to the established MRLs by major regulatory agencies in Brazil (ANVISA), the United States (US-EPA), and Europe (CE). The compounds showed acceptable recovery levels of 71–109% with a standard deviation less than 15%. The method was applied to determine pesticide residues in mango samples. For 12 samples, five compounds (chloroneb, propachlor, α-chlordane, chlorpyrifos, DCPA, chlorobenzilate, and trans-permethrin) were detected, with contents of 0.004–0.042 mg kg−1. For chloroneb, propachlor, and α-chlordane, the found concentrations were above the maximum permitted residue limit, according to data from the European Commission.

A comprehensive retrospective analysis of pesticide metabolites in urine was developed, using liquid chromatography coupled to Orbitrap high-resolution mass spectrometry (UHPLC-HRMS) that includes both post-run target (suspect screening) and non-target screening. An accurate-mass database comprising 263 pesticide metabolites was built and used for the post-run screening analysis. For non-target analysis, a “fragmentation-degradation” relationship strategy was selected. The proposed methodology was applied to 49 real urine samples from pregnant women. In the post-target analysis 26 pesticide metabolites were tentatively identified, 8 of which (2-diethylamino-6-methyl-pyrimidinol; 3-ketocarbofuran; 4,6-dimethoxy-2-pyrimidinamine; 4-hydroxy-2-isporopyl-6-methylpyrimidine; diethyl malate; diethyl maleate; N-(2-Ethyl-6-methylphenyl)-2-hydroxyacetamide and propachlor oxanilic acid ) were confirmed using analytical standards. Likewise, one unknown degradation product, methyl-N-phenylcarbamate was elucidated in the non-target screening. Finally, the real urine samples were grouped according to their origin applying a metabolomic approach.

This study aimed at investigating the chemical composition and in vitro antimicrobial activity of juniper (Juniperus communis L.) berries essential oils (EOs), including commercial samples as well as the oil hydrodistilledfromberriesgrowninPortugal,for which few information is available in the literature.The analysis was performed by gas chromatography coupled to mass spectrometry detection (GC/MS) allowing the identification of a total of 97 compounds. The EOs showed different chemical profiles with only one being according to the European Pharmacopoeia 8 requirements. The laboratory-hydrodistilled EO was characterized by its high content in α-pinene (41.6%), followed by β-pinene (27.6%) and limonene (6.4%), commercial EO1 by α-pinene (31.1%), β-myrcene (16.3%) and sabinene (7.5%) and commercial EO2 by δ-cadinene (16.0%), α-pinene (12.2%) and sabinene (9.4%). The distinct chemical profiles were also evidenced by principal components analysis (PCA), with a clear separation of the evaluated EOs. One of the commercial samples, showed the presence of propachlor, a banned herbicide in the European Union. All the EOs showed relevant antimicrobial activity as they presented microbicidal activity against Candida albicans and at least six of the ten tested bacteria. Commercial EO2 showed a higher biological activity, as it was active against all tested microorganisms, which could be related to its higher content in sesquiterpenes, in particular those oxygenated. Overall, results support the use of Juniper communis L. berries EO as an antiseptic in traditional medicine and highlight its potential as a biopreservative that could be used in different industries. The authors acknowledge the technical support given by Maria João Afonso (ESTiG, IPB). The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013). Soraia I. Falcão thanks FCT for the Post-Doc grant SFRH/BPD/118987/2016. info:eu-repo/semantics/publishedVersion

The molecularly imprinted polymers (MIPs) are used as the base material of solid phase extraction (SPE) for the separation and concentration of the propachlor herbicide (Prop) in different environmental matrix. Accordingly, we prepared MIPs on the surface of modified silica gel using propachlor as a template, acrylamide (AA) as functional monomers, ethylene glycol dimethacrylate (EGDMA) as a cross-linker and 2,2-azo-bis-isobutyronitrile (AIBN) as an initiator. The MIP structure was characterised using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Synthesised MIPs had a specific ability to detect the template Prop. The high selectivity solid phase extraction cartridges of molecularly imprinted polymers (MISPE) containing MIP Prop particles were prepared. The optimised Prop-MISPE procedure was developed for enrichment or clean-up of propachlor residues in water, soil and rice samples. Concentrations of propachlor in the samples were analysed by high performance liquid chromatography. Overall, the newly developed technique provides an analytical platform to quantify the trace amount of propachlor residues in multi or complex environmental and food media.

Resumo: O pepino está entre as culturas abrangidas pelo programa do governo brasileiro que monitora a qualidade dos alimentos no mercado varejista quanto à presença de resíduos de agrotóxicos e afins. As amostras avaliadas pelo programa contemplam apenas pepino tipo salada, não incluindo amostras resultantes do processamento industrial para consumo em forma de picles. Este trabalho teve como objetivo realizar análise de resíduos de agrotóxicos em amostras de pepinos para conserva in natura e industrializados, a fim de verificar sua conformidade com a legislação. As amostras de pepino foram coletadas em 18 de novembro de 2013 em cinco municípios do Alto Vale do Itajaí, sob coordenação da Epagri, Estação Experimental de Ituporanga, SC. Foram coletadas sete amostras: três amostras de pepinos in natura (uma em lavoura cultivada sem uso de agrotóxicos na área experimental da Epagri e duas em lavouras de produtores convencionais); quatro amostras de pepinos industrializados (uma amostra de pepino orgânico e três amostras de pepino convencional). A identificação dos resíduos de agrotóxicos foi feita utilizando-se o método analítico de multirresíduos ou metodologias específicas, utilizadas pelos laboratórios de saúde pública. As determinações analíticas indicaram a presença de cinco princípios ativos não autorizados para o pepino, quais sejam carbendazim, fluopicolida, propaclor e propamocarbe e concentrações de tiametoxam acima do limite máximo permitido para a cultura. Imidacloprido, outro princípio ativo encontrado nos frutos, estava em situação regular. Os resíduos de agrotóxicos foram encontrados apenas nas amostras de frutos de pepineiros cultivados em manejo convencional, tanto para o produto in natura quanto industrializado. Os resultados sugerem que o aperfeiçoamento de sistemas produtivos sustentáveis e com remuneração mais vantajosa aos produtores, aliado a estratégias para ampliar o consumo de alimentos saudáveis, devem ser fomentados na cadeia produtiva Abstract: Cucumber is among the crops included in the Brazilian government program that monitors pesticides and similar chemical residues in food available at the retail market. The samples evaluated by the program include only cucumber for the fresh market, but not cucumber for the industrial processing as pickles. We aimed to carry out analysis of pesticide residues in pickling cucumbers samples, in natura and processed, in order to verify their compliance with the law. The samples of pickling cucumber were collected in November 18, 2013 in five municipalities of Alto Vale do Itajai, under the coordination of Epagri, Ituporanga Experimental Station, Santa Catarina State, Brazil. Seven samples were collected: three samples of cucumbers in natura (one from a pesticide-free crop in the Epagri experimental area and two from conventional crop farms); four samples of processed cucumbers (one sample of organic cucumber and three samples of conventional cucumber). The identification of pesticide residues was carried out using the multiresidue method or specific methodologies used by the public health laboratories. The analytical determinations detected the presence of five unauthorized active ingredients for cucumber, namely carbendazim, fluopicolide, propachlor and propamocarb and concentrations of thiamethoxam above the limit allowed for the crop. Imidacloprid, another active ingredient found in the fruits, was within safe level. The pesticide residues were found only in samples of fruits from conventional crop, both in natura and industrialized. The results suggest that the improvement of sustainable production systems with more advantageous remuneration for farmers, coupled with strategies to increase the consumption of healthy foods, should be fomented in the productive chain.

The residue levels of organochlorine (OCP) and organophosphorus (OPP) in some dairy products and baby foods samples in Assiut markets Egypt were determined. The concentrations of OCP and OPP were determined in milk powder, plain yoghurt, fruit yoghurt, breakfast cereals, wheat cereal-based baby foods, rice cereal-based baby foods and vegetables and fruit-based baby foods by gas chromatography/mass spectrometry. In dairy products, the highest values of OCP and OPP were 9.346 ± 0.950 μg/kg methoxychlor in fruit yoghurt and 2.282 ± 0.400 μg/kg disulfoton in plain yoghurt, respectively. Propachlor, dieldrin (OCP), chlorpyrifos, and parathion- methyl (OPP) were not detected in any dairy product samples. Maximum amounts of methoxychlor (12.710 ± 0.700 μg/kg) and disulfoton (5.369 ± 0.510 μg/kg) were recorded in vegetables and fruit-based baby foods, and wheat cereal-based baby foods, respectively. The analysis of dairy products and baby foods showed lower pesticides values than the permissible limit set by the European Commission in all products, except methoxychlor (OCP) in vegetables and fruit-based baby foods. The results will help in a scientific assessment of the implications of pesticide residues with regards to human risks in Egypt.

Hormesis is a dose-response phenomenon that is characterized by low-dose stimulation and high-dose inhibition. This biphasic dose-responses have had a long and extensive history in the fields of chemical toxicology, radiation biology and pharmacology. Hormesis has been found from bacteria, fungi, plants and animals, but hormesis in plants has received relatively little attention. Thus principles, occurrence, factors affecting the expression of hormetic responses, and their mechanisms in plants induced by herbicides are reviewed to provide the potentials for crop enhancement. Bromacil, bromoxynil, chloramben, propachlor, terbacil, EPTC, MSMA, and glyphosate at low doses showed stimulatory response in growth. Subtoxic dose of glyphosate increased sucrose content in sugarcane that is used worldwide in sugarcane production. Low dose of protoporphyrinogen-inhibiting herbicides induced increased pathogen defence, and low dose of triazine herbicides improved nitrogen metabolism and increased protein content in some crops. Further researches on potential benefits and risks of hormesis and its mechanism are needed for application of crop enhancement in agriculture.

The purposes of this study were to understand the sorption–desorption characteristics of propachlor in three types of soils with added solid organic matters and the effect of solid organic matters on propachlor mobilization in soil microstructures. Three soil types, Eutric gleysols (EG), Hap udic cambisols (HUC), and Haplic alisol (HA), along with the lakebed sludge (SL) and pig manure compost (PMC), were used in the study. The sorption and desorption experiments were carried out using the standard batch equilibration method. Soil column leaching was performed with soil samples packed into PVC columns. Soil thin-layer chromatography was performed using soils and water mixture spread on a 0.5–0.7-mm thick layer over 20 × 10-cm glass plates. Propachlor was shown to be more mobile in EG and HUC than in HA. Application of PMC and SL to soils affected the propachlor mobilization in the soils. Using batch experiment, soil column, and soil thin-layer chromatography, we showed that addition of SL and PMC increased the sorption and decreased desorption of propachlor in the soils. Addition of PMC and SL reduced the total concentration of propachlor in the soil leachate and migration of propachlor in the soil profiles. Physicochemical properties of the three soils were analyzed and showed that the content of organic carbon (in percentage) was higher in Haplic alisol than in Eutric gleysols and Hap udic cambisols. The soil organic matter played critical roles in modifying the absorption and mobility of organic chemicals (e.g., herbicide and contaminants) in soil ecosystem.

The process of in situ chemical oxidation (ISCO) by persulfate (S(2)O(8)(2-)) can be accelerated by metal ion activation, which more effectively degrades subsurface pollutants by enhancing sulfate radical (SO(4)(-)) generation. This study compared the results of propachlor degradation by Cu(2+) and Fe(2+) activated persulfate and revealed differing degradation kinetics and mechanisms between the two types of activation system. The activation of persulfate by Fe(2+) ions generally resulted in rapid degradation in the early stage, but was accompanied by a dramatic decrease in efficiency due to the rapid depletion of Fe(2+) by the sulfate radicals generated. In contrast, the Cu(2+) activated persulfate had a longer lasting degradation effect and a proportionally greater degradation enhancement at elevated Cu(2+) concentrations. An optimal Fe(2+) concentration should be sought to activate the persulfate, as a high Fe(2+) concentration of 2.5mM or above, as was used in this study, may inhibit propachlor degradation due to the competitive consumption of sulfate radicals by the excess Fe(2+) ions. Higher temperatures (55°C compared with 30°C) resulted in enhanced metal activation, particularly with the Cu(2+) activated system. Furthermore, acidic conditions were found to be more favorable for propachlor degradation by metal activated persulfate. The ecotoxicity of degraded propachlor samples, which was indicated by average well color development (AWCD) for its microbial community activity, was confirmed to be decreased during the degradation processes with these two ions activated persulfate.

BACKGROUND: Recently in Korea, the import of agricultural products is rising due to the increasing amount of trade. Unregistered pesticides, allidochlor, propachlor, propham, cycloate, diallate and pebulate are widely used as pesticides for rice cultivation in foreign countries, while they are not registered in Korea. Therefore, the residue amount of imported agri-foods should be verified using the proper official analytical method for each of them that has not registered in Korea. METHODS AND RESULTS: This work was conducted to apply the official method of Korea Food & Drug Administration (KFDA) for determining multi class pesticide multiresidues in agricultural commodities. Brown rice and orange which have different characteristics as a matrix were selected as representative samples for residue analysis. The recoveries of cycloate, diallate and pebulate by GC/MS in fortified brown rice and orange with levels of 0.04~0.4 mg/kg were ranged from 82.8% to 110.3%. The quantification limits of three pesticides in brown rice and orange were 0.04 mg/kg. CONCLUSION: As a result, this method can surely be used as an official method for routine analysis of unregistered pesticides in Korea for imported agri-food.

Currently, herbicides are widely used in various combinations at many stages of cultivation and during postharvest storage. There are increasing concerns about the public health impact of herbicide degradation byproducts that may be present in water bodies used either as drinking water or for recreational purposes. This work investigated the sulfonic acid and oxanilic acid degradation products of metolachlor, alachlor, acetochlor, and propachlor in a variety of water bodies. The objective was to develop a fast, accurate, and easy method for quantitative analysis of herbicide degradation products using liquid chromatography with tandem mass spectrometry without solid phase extraction, but performing levels of detection lower than those obtained in previous studies with solid phase extraction. This research also screened 68 water samples, both untreated source water and treated water, from 34 water treatment plants in Missouri. Finally, it examined seasonal trends in levels of those degradation products by collecting and testing samples monthly. This highly sensitive method can analyze these degradation products to low ng/L levels. The method limit of quantification ranges from 0.04 to 0.05 ppb for each analyte; and quantitative analyses show a precision with RSDs of around 0.6% to 3% in treated water and 2% to 19% in untreated source water. Concentrations of alachlor ESA, acetochlor OA, metolachlor OA, and metolachlor ESA were detected from the Missouri River and the Mississippi River water bodies in summer time. Occurrences of these compounds in treated water samples are all lower than those in the untreated source water samples.

Alachlor and butachlor are chloracetanilide herbicides that induce olfactory tumors in rats, whereas propachlor does not. The mechanism by which alachlor induces tumors is distinct from many other nasal carcinogens, in that alachlor induces a gradual de-differentiation of the olfactory mucosa (OM) to a more respiratory-like epithelium, in contrast to other agents that induce cytotoxicity, followed by an aberrant regenerative response. We studied biochemical and genomic effects of these compounds to identify processes that occur in common between alachlor- and butachlor-treated rats. Because we have previously shown that matrix metalloproteinase-2 (MMP2) is activated in OM by alachlor, in the present studies we evaluated both MMP2 activation and changes in OM gene expression in response to carcinogenic and non-carcinogenic chloracetanilide treatments. All three chloracetanilides activated MMP2, and > 300 genes were significantly up- or downregulated between control and alachlor-treated rats. The most significantly regulated gene was vomeromodulin, which was dramatically upregulated by alachlor and butachlor treatment (>60-fold), but not by propachlor treatment. Except for similar gene responses in alachlor- and butachlor-treated rats, we did not identify clear-cut differences that would predict OM carcinogenicity in this study.

A magnetic photocatalyst was prepared by modification of TiO(2) nanoparticles (Degussa P25) with nanocrystalline gamma-Fe(2)O(3) nanoparticles through a protective lining made up of two oppositely charged polyelectrolytes. As-prepared magnetically separable photocatalysts differing in gamma-Fe(2)O(3) loading (3, 8, 13, 20 and 30 wt.%) were characterized by XRD, TEM, thermal analysis, Mossbauer and magnetic measurements. The photocatalytic efficiency of the nanocomposite catalysts was evaluated using a chloroacetanilide herbicide (propachlor) in water as model compound. The primary degradation of propachlor followed pseudo-first-order kinetics according to the Langmuir-Hinshelwood model. Generally, all magnetic photocatalysts exhibit good catalytic activity towards organic pollutants, do not suffer from photodissolution and can be reused several times without any decrease in their photocatalytic activity. (C) 2008 Published by Elsevier B.V. Applied Catalysis B-Environmental

WOS: 000357235400023, PubMed ID: 25989604, In this study, electrochemical removal of propachlor from water has been investigated by electro-Fenton process which provides continuous electrochemical production of hydroxyl radical which is a highly oxidizing agent. This radical can react with propachlor unselectively and can oxidize it into carbon dioxide and water. Effects of applied current, catalyst (Fe-2(SO4)(3)) and supporting electrolyte (Na2SO4) concentrations on the degradation rate of propachlor have been examined and determined as 200 mA, 0.20 mM and 25 mM, respectively. The oxidation reaction showed a second-order reaction kinetic with an absolute rate constant value of (3.6 +/- 0.2) x 10(9) M-1 s(-1) which was determined by competition kinetic experiments. Total organic carbon analysis was employed to follow the mineralization of propachlor. The total mineralization was completed in a seven-hour electrolysis at 300 mA indicating that the electro-Fenton process is very effective in the mineralization of propachlor in water. Oxidation of propachlor with hydroxyl radical led to the formation of intermediate species. Some of these species were detected and quantified by chromatographic and spectroscopic methods such as HPLC, GC-MS and IC. A plausible mineralization pathway for the electrochemical removal of propachlor was proposed based on the identified by-products, Anadolu University Research Projects Commission [1401F009], Financial support of Anadolu University Research Projects Commission (Project No: 1401F009) is gratefully acknowledged.

A laboratory study has been conducted to examine the retention processes of nitrogen and pesticides through vegetated buffer zones compared to bare soil. Soil columns with low biological activity and vegetation columns with normal biological activity were tested. Pesticides frequently used in vegetable production (namely aclonifen, azinphos-methyl, chlorpropham, diazinon, dimethoate, fluazinam, iprodione, linuron, metalaxyl, metamitron, metribuzin and propachlor) equal to 1/50 to 1/5 part of recommended doses, and nutrients equal to 1, 5 and 20 mg N/L and 0.2 mg P/L, were added. The pesticide retention was more than 60% for all pesticides, except dimethoate, with a retention of about 30% in columns with low microbial activity. Biological transformation and plant uptake were important for removal of nitrogen and organic matter. Nitrogen retention was high (over 90%) in vegetation columns. Plant uptake and phosphorus content in soil were important for phosphorus retention.

The biodegradation of the herbicides hexazinone, metribuzin, metobromuron and propachlor was evaluated in liquid cultures of an adapted and a non-adapted mixed microbial culture obtained from a wastewater treatment plant. All herbicides were poorly degraded after 50 days ( 50 % ) . The adaptation of microbial culture prior to the biodegradation test shortened only the lag-time in degradation of hexazinone. The level of biodegradation correlated with the log K ow values of the molecules tested ( R 2 = 0.970 ). Metobromuron at 100 mg L - 1 inhibited the metabolism of aniline by the mixed culture.

Propachlor and other chloroacetanilide herbicides are frequently detected contaminants of groundwater and surface water in agricultural regions. The purpose of this work was to develop a new approach to remove propachlor residues from the environment via chemical remediation by the nitrification inhibitor thiourea. The transformation processes of propachlor and thiourea mixed in aqueous solution, sand, and soil were elucidated. Analysis of transformation products and reaction kinetics indicated that an SN2 nucleophilic substitution reaction occurred, in which the chlorine of propachlor was replaced by thiourea, detoxifying the herbicide. It appears that propachlor undergoes a catalytic reaction in sand or soil amended with thiourea, which results in a significantly accelerated transformation rate as compared to the reaction in aqueous solution. The second-order reaction process was examined at different temperatures to investigate the role of the activation energy. The enthalpy of activation (ΔH) for the ...

For some triazines and phenylurea derivatives no reliable KOW values were available from literature. The log KOW values were determined directly with the shake-flask procedure and also indirectly using the reversed-phase high-performance liquid chromatography (RP-HPLC) method in the isocratic and gradient elution mode, respectively. Atrazine, as a well-investigated substance, and two herbicides of different chemical structures (acid amides) were included in this study. Both RP-HPLC methods yield log KOW values comparable among themselves and identical with the shake-flask results for methabenzthiazuron (2.5), chloroxuron (3.8), sebutylazine (3.2), and atrazine (2.6). For the atrazine metabolites investigated, the RP-HPLC-derived log KOW values are significantly less than those directly measured (1.0 for desethylatrazine and 1.5 for desisopropylatrazine). In contrast to these findings, considerably higher log KOW values were obtained for the two acid amides propachlor and metazachlor with both RP-HPLC meth...

The photooxidation of several herbicides belonging to the acetamides group (specifically propachlor, metolachlor and butachlor) by means of a monochromatic UV irradiation in ultrapure water was studied. In the case of propachlor, the quantum yield for its photolysis was evaluated directly, and a value 0.127 ± 0.01 mol Eins−1 was obtained independent of the pH. The quantum yields for the photolysis of metolachlor and butachlor were determined by using a competition kinetic model which used propachlor as reference compound, and values of 0.56 ± 0.05 and 0.78 ± 0.04 mol Eins−1 were deduced respectively for metolachlor and butachlor. In a second step, the elimination of the selected herbicides in some natural and mineral waters was studied by means of several oxidation systems: UV radiation alone, and UV radiation combined with hydrogen peroxide and ozone. The influence of the operating variables in these processes (acetamide type, presence or absence of tert-butyl alcohol and types of waters) are discussed as a consequence of the amounts of herbicides removed. Two different kinetic studies were carried out for the oxidation of the herbicides: the first one for UV radiation alone and UV radiation combined with H2O2; the second one for the combination UV radiation plus ozone. In these studies, the specific rate constants were evaluated in every process. Finally, kinetic models for the prediction of the elimination of these herbicides in the natural waters selected by the different oxidation systems are proposed. The values of concentrations predicted by these models agree well with the experimental results obtained. Copyright © 2004 Society of Chemical Industry

Adsorption of chloroacetanilide herbicide acetochlor, alachlor, metolachlor and propachlor on soils and soil components was determined, and the structural differences of these herbicides were used to explain the order of sorptivity. Adsorption isotherms for all herbicide-soil combinations conformed to the Freundlich equation, and Ki increased with increasing soil organic carbon content. Kd on soil humic acid was greater than that on clay, but association of humic acid with clay reduced the overall adsorption. On all soils and soil humic acids, herbicide adsorption decreased in the order: metolachlor > acetochlor > propachlor > alachlor. On Ca(2+)-montmorrilonite, the order changed to metolachlor > acetochlor > alachlor > propachlor. FT-IR spectra of herbicide-clay or herbicide-humic acid-clay mixtures showed that H-bonding and charge transfer were the primary interaction pathways between these compounds and the surface of clay or humic acids. The different moieties attached to 2-chloro-acetanilide and their unique arrangement may have influenced the binding mechanisms and thus the sorptivity of these herbicides. This study indicates that the structural difference of pesticides in the same classes may be used as a molecular probe to obtain a better understanding of sorption mechanisms of pesticides on soil.

The oxidation by ozone and by the combination O3/H2O2 of four herbicides included in the acetamide group (acetochlor, metolachlor, propachlor, and butachlor) was studied. In a first step, the rate constants were determined for the reactions of the selected herbicides with ozone (kO3) and OH radicals (kOH). The sequence of reactivities for solutions in ultrapure water were as follows: for ozonation, metolachlor < propachlor < acetochlor < butachlor; for oxidation by hydroxyl radicals, propachlor < acetochlor < metolachlor < butachlor. The rate constants for the reaction with ozone ranged from 1.1 to 5.3 L/(mol·s), indicating that direct reactions with ozone will play a minor role during ozonation processes. Values for kOH ranged from 4.6 × 109 to 7.4 × 109 L/(mol·s). Therefore, reactions with OH radicals will be the major pathway for the oxidative transformation of these four herbicides, even when conventional ozonation is applied. In a second step, the oxidation of the investigated herbicides during ozon...

Specific polyclonal antibodies against the herbicide butachlor [2-chloro-N-(2,6-diethylphenyl)-N-(butoxymethyl)acetanilide] were obtained from rabbits immunized with butachlor-3-mercaptopropionic acid (BMPA), coupled to bovine serum albumin (BSA) and soybean trypsin inhibitor. Competitive enzyme-linked immunosorbent assays with photometric detection based on either immobilized antibody (direct assay) or immobilized antigen (indirect assay) were developed and optimized for quantification of butachlor. The best assay sensitivity was observed using antibodies against BMPA–BSA immunogen and immobilized antigen format, where the limit of detection was 0.02 ng ml−1, the standard curve midpoint (IC50) was 2.4 ng ml−1 and assay duration was 1.5 h. Antibodies were capable of the specific detection of butachlor with cross-reactivities towards structurally related chloroacetanilide herbicides (alachlor, acetochlor, dimethachlor, metolachlor, propachlor) below 0.3%. Direct and indirect assays are compatible with up to 1–2%, v/v of methanol and ethanol in the analyzed probe. Assay application to the analysis of mineral, ground and surface water resulted in butachlor recoveries varying between 70 and 118% between 10 and 100 ng ml−1 herbicide concentrations.

When pesticides are used in arable watersheds, residues are usually found in the recipients. However, small constructed wetlands (CWs) in first and second order streams can reduce the loss of pesticides, since water purification processes are stimulated. This paper presents the results of adding 13 pesticides to a CW in Norway. The relative retention increased between 0 and 67% for the pesticides fluroxypyr, bentazone, dicamba, mecoprop, propiconazole, MCPA, dichlorprop, linuron, fenpropimorph, metalaxyl, metribuzin, metamitron and propachlor. In many cases, the CW reduced the peak concentrations to values regarded as non-toxic for aquatic life, even though the wetland covered less than 0.4% of the watershed surface area, and the average hydraulic load often was above 0.8 m d-1. Possible retention factors were adsorption to soil particles and organic matter, sedimentation of particles, low or high redox-potential, and biodegradation of nitrogen-rich pesticides. However, the retention processes are complex, and are not fully understood.

Chloroacetanilides are pre-emergence herbicides for the control of annual grasses and broadleaf weeds. As a result of their extensive use, residues are often found in surface waters. Observed simultaneous occurrence of different chloroacetanilide herbicides gives reason for concern about potential combination effects on aquatic non-target organisms. This study aimed to clarify whether joint effects of various chloroacetanilide herbicides may be predictable from knowledge of concentration-response relationships of single substances. Whether the chloroacetanilides all share the same mode of action is unclear. Therefore we investigated the predictive value of two alternative concepts for the prediction of combined effects: concentration addition, which assumes a similar mode of action, and independent action, which is based on the idea of a dissimilar mode of action of the mixture components. Eight chloroacetanilides (acetochlor, alachlor, butachlor, dimethachlor, metazachlor, metolachlor, pretilachlor and propachlor) were experimentally tested for their individual as well as for their combined effects in mixtures on the reproduction of the green alga Scenedesmus vacuolatus. Individual chloroacetanilides impaired algal reproduction, with EC50 values ranging from 3 to 232 microg litre(-1). The differences in EC50 values were strongly correlated with the lipophilicities of the compounds. Effects of chloroacetanilide mixtures were considerably higher than those of the individual components: a complete inhibition of algal reproduction was observed when every mixture component was present in a concentration that would cause only 5% effect if applied singly. However, the combined effects proved to be predictable by using the concept of concentration addition. The alternative concept, independent action, distinctly underestimated the mixture toxicity. These findings (1) indicate a similar mechanism of action of chloroacetanilides in algae and (2) reinforce the view that concentration addition is a reasonable assumption for the predictive hazard assessment of groups of similarly acting herbicides.

Specific polyclonal antibodies towards acetochlor (2-chloro- N -(ethoxymethyl)- N -(2-ethyl-6-methylphenyl)acetamide) were obtained from rabbits immunized against a 3-mercaptopropionic acid derivative of acetochlor, covalently attached to bovine serum albumin. A polarization fluoroimmuoassay (PFIA) based on these antibodies was developed and optimized to detect acetochlor in water samples. The optimized PFIA had a detection limit of 9 µg/L, linear working range from 50 to 5500 µg/L and within-assay coefficient of variation less than 4%. Cross-reactivity studies demonstrated that these antibodies are capable of specific detection of acetochlor amongst structurally related chloroacetanilide herbicides. Assay cross-reactivity values were: alachlor 0%, metolachlor 2.4%, propachlor 0%, butachlor 0.2% and dimethachlor 0.5%. Five organic solvents commonly used in sample extraction were evaluated for their effect on acetochlor PFIA performance, and methanol and ethanol were found to be compatible with the assay u...

Cecil sandy loam soils (ultisol) from forest (coniferous and deciduous), pasture, and arable ecosystems were sampled (0–10 cm) in the vicinity of Athens, Georgia, USA. Soil from each site was subdivided into three portions, consisting of untreated soil (control) as well as live and sterile samples treated with the fungicide metalaxyl and the herbicide propachlor at 10 mg kg–1 soil. Pesticide transformation rate, basal respiration (basal) and substrate-induced respiration (SIR) rates, and microbial metabolic quotient (qCO2) were measured for the initial application of metalaxyl [methyl-N-(2,6-dimethylphenyl)-N-(metoxyacetyl)-DL-alaninate] or propachlor (2-chloro-N-isopropyl-acetanilide) at 22°C and 60% water holding capacity. Positive correlations were found for the following: metalaxyl transformation rate constant (Kmet) and basal (r=0.73); Kmet and SIR (r=0.83); propachlor transformation rate constant (Kpr) and basal (r=0.89); and Kpr and SIR (r=0.91). Regression analysis of pesticide transformation rate and soil respiration activity, coupled with specific soil properties (pH, Corg, and clay content), revealed a positive correlation between K and SIR for Corg (r=0.88 and 0.98, for metalaxyl and propachlor, respectively). qCO2s were not significantly different (P=0.05) in propachlor-amended and pesticide-free soils. Metalaxyl amendment resulted in a change in the ecophysiological status of the soil microbial community as expressed by qCO2. The qCO2 values in metalaxyl-amended soils were significantly greater (P=0.05) in pine forest (by 25%) and arable and pasture (by 20%) soils compared to unamended soils. Differences in qCO2 values may represent the magnitude of pesticide-induced disturbance. The duration of this disturbance was greater in the pine forest soil (48 days) compared to arable and pasture soils (21 and 15 days, respectively).

Fractionated Al-pillared (code name AZA) and Fe–Al-pillared (code name FAZA) clays and mesoporous alumina aluminum phosphates (AAPs) were contacted with aqueous, atrazine, propazine, prometryne, propachlor, propanil and molinate solutions at a concentration range of between 1 and 20 mg/l, in batch equilibrium experiments in order to determine their adsorption properties. The pillared clays showed an improved affinity which allowed the adsorption of the studied herbicides to occur much more efficiently than in the case of AAPs. The removed amounts of the studied herbicides by using the pillared clay materials reached 95.3% for atrazine, 92.2% for propazine, 98.5% for prometryne, 60.9% for propachlor, 86.8% for propanil and 70.2% for molinate. The iron substitution in FAZA pillared clay did not show great differences in adsorption capacity. The adsorption of s -triazines on mesoporous AAPs decreased with the alkyl substitution of the lateral chains, thus atrazine was the most adsorbed compound. The removal of propachlor by AAPs decreased with the increase of P/Al ratio. The material with P/Al=0.4 ratio was more efficient for the removal of molinate and propanil. The amounts of herbicides decomposed during the treatment were higher for AAPs in comparison with those for AZA and FAZA.

Adsorption of the chloroacetanilide herbicides acetochlor, alachlor, metolachlor, and propachlor was determined on soils and soil components, and their structural differences were used to explain their sorptivity orders. On all soils and soil humic acids, adsorption decreased in the order: metolachlor > acetochlor > propachlor > alachlor. On Ca 2+ -saturated montmorillonite, the order changed to metolachlor > acetochlor > alachlor > propachlor. FT-IR differential spectra of herbicide-clay or herbicide-humic acid-clay showed possible formation of hydrogen bonds and charge-transfer bonds between herbicides and adsorbents. The different substitutions and their spatial arrangement in the herbicide molecule were found to affect the relative sorptivity of these herbicides by influencing the reactivity of functional groups participating in these bond interactions. It was further suggested that structural characteristics of pesticides from the same class could be used to improve prediction of pesticide adsorption on soil.