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PubMed2004

Environmental impact of diuron transformation: a review.

Diuron is a biologically active pollutant present in soil, water and sediments. A synthesis of literature data on its physicochemical properties, partitioning behaviour, abiotic and biotic transformations, toxicological and ecotoxicological impacts has been here performed. Data have shown that diuron is generally persistent in soil, water and groundwater. It is also slightly toxic to mammals and birds as well as moderately toxic to aquatic invertebrates. However, its principal product of biodegradation, 3,4-dichloroaniline exhibits a higher toxicity and is also persistent in soil, water and groundwater. Thus, diuron indirectly possesses a significant amount of toxicity and could be a potential poisoning pesticide contaminant of groundwater. Unfortunately, groundwater contamination will still persist despite the progressive suppression of diuron (Directive 200/60/CE). Therefore, determining the main factors influencing its degradation and its ecotoxicological effects on the environment and health could provide a basis for further development of bioremediation processes.

Animals↗
PubMed2002

Isolation, characterization and diuron transformation capacities of a bacterial strain Arthrobacter sp. N2.

A bacterial strain able to transform diuron was isolated from a soil by enrichment procedures. Strain isolation was realized by plating on minimal-agarose medium spread with this herbicide and selecting the colonies surrounded by a clear thin halo. One strain was characterized and identified as an Arthrobacter sp. It metabolized diuron and the final transformation product, 3,4-dichloroaniline, was produced in stoichiometric amounts. The transformation of diuron at different concentrations was more efficient in the presence of alternative sources of carbon and nitrogen. The bacterial activity was also evaluated in soil microcosms with a consequent disappearance of diuron and concomitant appearance of 3,4-dichloroaniline, of which the concentration decreased thereafter. Bacterial cells inoculated in the microcosms survived as viable but eventually nonculturable cells.

Arthrobacter↗
PubMed2002

Photodegradation of the antifouling compounds Irgarol 1051 and Diuron released from a commercial antifouling paint.

The antifouling compound Irgarol 1051 and its degradation product M1 (also known as GS26575), along with another antifouling compound Diuron, have recently been found in Japanese coastal waters. This study was undertaken to find the origin of these chemicals and investigate their aquatic fate. Five glass plates, each coated with 1 g of antifouling paint containing Irgarol and Diuron, were submerged in 250 ml of five different test waters and the plates removed after several months. The aqueous solutions were divided into two groups: one exposed to natural sunlight, and the other kept in the dark as a control. Irgarol and Diuron were detected in all aqueous solutions, suggesting leaching from antifouling paints is the origin of these antifouling biocides found in Japanese coastal waters. Under sunlight conditions, Irgarol underwent a rapid degradation to produce M1, which remained even after Irgarol had disappeared from the system. These compounds were persistent in any aqueous solutions tested under dark conditions, indicating high stability to hydrolysis. Diuron and M1 were more persistent than Irgarol under sunlight irradiation. Since these compounds have high herbicidal activities, their ultimate impact on aquatic ecosystems is closely related to their aquatic fate.

Diuron↗
PubMed2003

Effect of Diuron on aquatic bacteria in laboratory-scale wastewater treatment ponds with special reference to Aeromonas species studied by colony hybridization.

Six laboratory-scale wastewater treatment ponds were filled with sediment and water obtained from a reference pond (a wastewater treatment plant located in a rural environment at Montel-de-Gelat, Puy-de-Dôme, France). They were kept at 20 degrees C, with alternative light and dark periods (12 h-12 h), and fed with raw effluent supplied weekly. Three of them were treated with Diuron (dissolved in DMSO) at a final concentration 10 mg/l, while the other three received only DMSO. Physico-chemical parameters, total bacteria, cultivable bacteria, and Aeromonas spp. were measured periodically until 41 days after the Diuron contamination. Total bacteria were treated with 4,6-diamidino 2-phenylindole (DAPI) and counted by epifluoroscence microscopy. The cultivable bacteria were quantified on plate count agar medium and Aeromonas spp. using colony hybridization. In the contaminated pilots, biochemical oxygen demand (BOD5), chemical oxygen demand (COD), suspended solids (SS), volatile suspended solids (VSS), ammonium, phosphorus, and bacteria increased, but dissolved oxygen decreased. The abundance of total bacteria, cultivable bacteria (multiplied by 30), and Aeromonas spp. increased for two weeks after Diuron introduction, reverting to initial values three weeks later. The percentage of cultivable bacteria relative to total bacteria was 0.2% in controls and 1.2% in treated pilots, while the percentage of Aeromonas spp. relative to cultivable bacteria decreased from 6-10% to 2%. Our results suggest that Diuron, which acts on the photosystem II of phototrophs, supports the development of cultivable bacteria through new carbon sources derived from the decomposition of photosynthetic micro-organisms, but does not specifically support Aeromonas spp.

Aeromonas↗
PubMed2003

Impact of the herbicides 2,4-D and diuron on the metabolism of the coral Porites cylindrica.

This study investigates the effects of two herbicides on the hermatypic coral Porites cylindrica. The herbicides tested were 2,4-D and diuron, since they are commonly used and have different toxic characteristics. Corals were exposed to 10 and 100 mg l(-1) 2,4-D, and to 10, 50 and 100 micro g(-l) diuron for 48 h respectively, and the effects were measured using an oxymeter and a diving PAM fluorometer. Coral gross primary production rate, gross primary production to respiration ratio and effective quantum yield were significantly reduced when exposed to 100 mg l(-1) 2,4-D while respiration seemed unaffected. All three concentrations of diuron caused a significant reduction in all measured parameters except respiration and maximum fluorescence yield, where a significant reduction was detected at 50 and 100 micro g(-1) diuron, respectively.

Animals↗
PubMed1996

Micronucleus induction by diuron in mouse bone marrow.

Diuron, a widely used substituted urea herbicide, induced the formation of micronuclei in bone marrow cells of Swiss mice. A single i.p. dose of 340 mg/kg b.w. diuron which is maximum tolerated dose (MTD) increased significantly the number of micronuclei at 30 h and 48 h time period. The dose of 170 mg/kg b.w. also induced the micronuclei formation in the above time period. However, a dose of 85 mg/kg b.w. was ineffective at the time periods studied. No induction of micronuclei was observed at 72 h time period after all the doses of diuron studied as compared to the solvent control. The diuron-induced frequency of micronucleated erythrocytes was independent of the sex of the test animals.

Animals↗
PubMed2005

FTIR approaches for diuron determination in commercial pesticide formulations.

Two strategies have been developed for Diuron determination by FTIR spectrometry, an off-line extraction and stopped-flow determination and a fully mechanized procedure, based on the on-line extraction of Diuron and FIA-FTIR measurement of the extracts. The aforementioned procedures have been compared with a reference chromatographic method. The off-line FTIR spectra were obtained at a nominal resolution of 4 cm(-1) from 4000 to 900 cm(-1) by accumulating 25 scans. Diuron was determined using peak height measurements at 1582 cm(-1) corrected using a baseline defined between 1562 and 1614 cm(-1). The waste generation of the off-line procedure was 3.4 mL chloroform for each sample, and the method provided a LOD of 40 microg g(-1), corresponding to 0.8% (w/w) Diuron in the original sample. The fully mechanized FIA method provided a LOD of 35 microg g(-1), which corresponds to 0.7% (w/w) in the solid sample and a maximum sampling frequency of the whole procedure of 30 h(-1), with a waste generation of 9.3 mL per sample, taking into account the volume of CHCl(3) required for sample dissolution and that need as a carrier. All those methods consume less organic solvent than a HPLC method, which involves the use of 39 mL of acetonitrile per sample and a sampling frequency of 12 h(-1).

Chromatography, High Pressure Liquid↗
PubMed2000

Evaluation of residual levels of benomyl, methyl parathion, diuron, and vamidothion in pineapple pulp and bagasse (Smooth cayenne).

The objective of this research was to study the residual levels of benomyl, methyl parathion, diuron, and vamidothion in pineapple bagasse and pulp. Benomyl (benlate), methyl parathion (Folidol 600), diuron (Krovar), and Vamidothion (Kilval 300) were applied pre-harvest to pineapples (smooth cayenne). After harvesting, the fruits were washed (100 ppm sodium hypochlorite) and the pulp was separated from the sub-products (peel, core, tops, and tails). The pulp was not submitted to any heat treatment. The sub-products and the juice expressed from them, were submitted to a blanching process (95 degrees C for 1 min). After separating the juice, the bagasse and pulp were analyzed for residues of diuron and benomyl by high performance liquid chromatography, and for residues of vamidothion and methyl parathion by gas chromatography using a TSD detector. No residues of benomyl, diuron, vamidothion, or methyl parathion were detected in the pulp within the quantification limits of the methods (0.1 mg/kg, 0.1 mg/kg, 0.005 mg/kg, and 0.005 mg/kg, respectively). Only methyl parathion (0.052 mg/kg) and vamidothion (0.021 mg/kg) were detected in the bagasse. The presence of these residues in the bagasse was probably due to the action of the wax found in the peel, which prevented the methyl parathion and vamidothion from dissolving in the juice. According to these results, the pulp was fit for human consumption, as far as pesticide residues were concerned, and the bagasse was fit for animal feed and similar applications, because the residual levels found were below the limits established for these compounds.

Benomyl↗
PubMed1981

The rapidly metabolized 32,000-dalton polypeptide of the chloroplast is the "proteinaceous shield" regulating photosystem II electron transport and mediating diuron herbicide sensitivity.

Mild trypsin treatment of Spirodela oligorrhiza thylakoid membranes leads to partial digestion of the rapidly metabolized, surface-exposed, 32,000-dalton protein. Under these conditions, photoreduction of ferricyanide becomes insensitive to diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea], an inhibitor of photosystem II electron transport. Preincubation of thylakoids with diuron leads to a conformational change in the 32,000-dalton protein, modifying its trypsin digestion and preventing expression of diuron insensitivity. Finally, light affects the susceptibility of the 32,000-dalton protein to digestion by trypsin. In other experiments, thylakoids specifically depleted in the 32,000-dalton protein were found to be deficient in electron transport at the reducing side of photosystem II but not at the oxidizing side or in photosystem I activities. Thus, the rapidly metabolized 32,000-dalton thylakoid protein in Spirodela chloroplasts fulfills the requirements of the hypothesized "proteinaceous shield" [Renger, G. (1976) Biochim. Biophys. Acta 440, 287-300] regulating electron flow through photosystem II and mediating diuron sensitivity.

Chloroplasts↗
PubMed1999

Sorption and desorption kinetics of diuron, fluometuron, prometryn and pyrithiobac sodium in soils.

The sorption and desorption characteristics of four herbicides (diuron, fluometuron, prometryn and pyrithiobac-sodium) in three different cotton growing soils of Australia was investigated. Kinetics and equilibrium sorption and desorption isotherms were determined using the batch equilibrium technique. Sorption was rapid (> 80% in 2 h) and sorption equilibrium was achieved within a short period of time (ca 4 h) for all herbicides. Sorption isotherms of the four herbicides were described by Freundlich equation with an r2 value > 0.98. The herbicide sorption as measured by the distribution coefficient (Kd) values ranged from 3.24 to 5.71 L/kg for diuron, 0.44 to 1.13 L/kg for fluometuron, 1.78 to 6.04 L/kg for prometryn and 0.22 to 0.59 L/kg for pyrithiobac-sodium. Sorption of herbicides was higher in the Moree soil than in Narrabri and Wee Waa soils. When the Kd values were normalised to organic carbon content of the soils (Koc), it suggested that the affinity of the herbicides to the organic carbon increased in the order: pyrithiobac-sodium < fluometuron < prometryn < or = diuron. The desorption isotherms were also adequately described by the Freundlich equation. For desorption, all herbicides exhibited hysteresis and the hysteresis was stronger for highly sorbed herbicides (diuron and prometryn) than the weakly sorbed herbicides (fluometuron and pyrithiobac-sodium). Hysteresis was also quantified as the percentage of sorbed herbicides which is not released during the desorption step (omega = [nad/nde - 1] x 100). Soil type and initial concentration had significant effect on omega. The effect of sorption and desorption properties of these four herbicides on the off-site transport to contaminate surface and groundwater are also discussed in this paper.

Adsorption↗
PubMed2004

Application of the IAS theory combining to a three compartments description of natural organic matter to the adsorption of atrazine or diuron on activated carbon.

The study of natural organic matter (NOM) adsorption on an activated carbon showed that equilibrium cannot be described according to a simple model such as a Freundlich isotherm and confirms the need for a closer description of the organic matter to simulate the competitive adsorption with micropollutants. A representation of the organic matter in three fractions is chosen: non-adsorbable, weak and strong adsorbable. The Ideal Adsorbed Solution Theory (IAST) can, under restrictive conditions, be used to effectively predict the competition between the pesticides and the organic matter. Therefore, it was noted that the model simulated with good precision the competition between atrazine or diuron and natural organic matter in aqueous solution for two activated carbons (A and B). The same parameters for the modeling of organic matter adsorption (Freudlich constants for two absorbable fractions) are used with the two pesticides. However, IAST does not allow correct modeling of pesticide adsorption onto two other (C and D) activated carbons in solution in natural water to be described. IAS theory does not reveal competition between diuron and NOM and pore blockage mechanism by the NOM is proposed as the major effect for the adsorption capacity reduction. However, the difference observed between the two pesticides could be due to in addition to the pore blockage effect, a particular phenomenon with the diuron, especially with D activated carbon. We can suppose specific interactions between the diuron and the adsorbed organic matter and a competition between adsorption sites of NOM and activated carbon surface.

Adsorption↗
PubMed2004

Sorption kinetics of atrazine and diuron in soils from southern Brazil.

Sorption kinetics of atrazine and diuron was evaluated in soil samples from a typical landscape in Paraná. Samples were collected (0-20 cm) in a no-tillage area from Mamborê, PR, which has been cultivated under a crop rotation for the last six years. Six sampling points of the slope were selected to represent a wide range of soil chemical and physical properties found in this area. Radiolabeled tracers (14C-atrazine and 14C-diuron) were used and the radioactivity was detected by liquid scintillation counting (LSC). Sorption was accomplished for increasing equilibration periods (0.5, 1.5, 3, 6, 12, 24, and 48 h). Kinetics data fitted adequately well to Elovich equation, providing evidences that soil reaction occurs in two distinct stages: a fast, initial one followed by a slower one. During the fast phase, 34-42 and 71-79% of total atrazine and diuron applied were sorbed to soil samples. No important differences were found among combinations of soil and herbicide sorption during the slow phase. The unrealistic conditions under batch experiments should be overestimating sorption in the fast phase and underestimating diffusion in the slow phase. Sorption of both herbicides was positively correlated to organic carbon and clay contents of soils, but atrazine was much less sorbed than diuron, showing its higher potential to contaminate groundwater, specially in sandy, low organic carbon soils.

Adsorption↗
PubMed2006

Fate of diuron and linuron in a field lysimeter experiment.

The environmental fate of herbicides can be studied at different levels: in the lab with disturbed or undisturbed soil columns or in the field with suction cup lysimeters or soil enclosure lysimeters. A field lysimeter experiment with 10 soil enclosures was performed to evaluate the mass balance in different environmental compartments of the phenylurea herbicides diuron [3-(3,4-diclorophenyl)-1,1-dimethyl-urea] and linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea]. After application on the agricultural soil, the herbicides were searched for in soil, pore water, and air samples. Soil and water samples were collected at different depths of the soil profile and analyzed to determine residual concentrations of both the parent compounds and of their main transformation products, to verify their persistence and their leaching capacity. Air volatilization was calculated using the theoretical profile shape method. The herbicides were detected only in the surface layer (0-10 cm) of soil. In this layer, diuron was reduced to 50% of its initial concentration at the end of the experiment, while linuron was still 70% present after 245 d. The main metabolites detected were DCPMU [3-(3,4-dichlorophenyl)-1-methylurea] and DCA (3,4-dichloroaniline). In soil pore water, diuron and linuron were detected at depths of 20 and 40 cm, although in very low concentrations. Therefore the leaching of these herbicides was quite low in this experiment. Moreover, volatilization losses were inconsequential. The calculated total mass balance showed a high persistence of linuron and diuron in the soil, a low mobility in soil pore water (less than 0.5% in leachate water), and a negligible volatilization effect. The application of the Pesticide Leaching Model (PELMO) showed similar low mobility of the chemicals in soil and water, but overestimated their volatilization and their degradation to the metabolite DCPMU. In conclusion, the use of soil enclosure lysimeters proved to be a good experimental design for studying mobility and transport processes of herbicides in field conditions.

Diuron↗
PubMed1987

Interaction of Herbicides and Quinone with the Q(B)-Protein of the Diuron-Resistant Chlamydomonas reinhardtii Mutant Dr2.

We have used the diuron-resistant Dr2 mutant of Chlamydomonas reinhardtii which is altered in the 32 kilodalton Q(B)-protein at amino acid 219 (valine to isoleucine), to investigate the interactions of herbicides and plastoquinone with the 32 kilodalton Q(B)-protein. The data contained in this report demonstrate that the effects of this mutation are different from those of the more completely characterized mutant which confers extreme resistance to triazines in higher plants. The mutation in C. reinhardtii Dr2 confers only slight resistance to a number of inhibitors of photosynthetic electron transport. Extreme triazine resistance results from an increase in the binding constant of the herbicide with the 32 kilodalton Q(B)-protein, in contrast the diuron binding constant for chloroplasts isolated from wild-type (sensitive) Chlamydomonas and the resistant Dr2 are indistinguishable. We conclude that the altered structure in the 32 kilodalton Q(B)-protein of Dr2 does not directly affect the diuron binding site. This mutation appears to alter the steric properties of the binding protein in such a way that diuron and plastoquinone do not directly compete for binding. This steric perturbation confers mild resistance to other herbicidal inhibitors of photosynthesis and alters the kinetics of Q(A) to Q(B) electron transfer.

Journal Article↗
PubMed1989

Increased diuron resistance in the joint expression of mutations located at the DIU2, DIU3 and DIU4 loci of Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, diuron blocks the respiratory pathway at the level of the bc1 complex. Two mitochondrially inherited loci, DIU1 and DIU2, located in the cytochrome b gene, and two nuclearly inherited loci, DIU3 and DIU4, have previously been identified. The present work genetically characterizes two double mutants. One mutant, Diu-217, carries two nuclearly inherited mutations, diu3-217a and diu-217b; the second mutant, Diu-783, carries the previously described nuclear mutation diu3-783 and a mitochondrial mutation diu2-783. Each mutation, independent of its location, exhibits a weak diuron resistance. The joint expression of two or three mutations leads to a cumulative or a cooperative enhanced diuron-resistant phenotype.

Alleles↗
PubMed1996

Biodegradation of three substituted phenylurea herbicides (chlortoluron, diuron, and isoproturon) by soil fungi. A comparative study.

As a part of a study conducted on the fate of xenobiotics in the environment, a selection of 90 strains of micromycetes, mostly isolated from soil and belonging to various taxonomic groups, have been cultivated in liquid synthetic medium with chlortoluron (100 mg.L-1), diuron (20 mg.L-1), and isoproturon (100 mg.L-1) for 5 days. Evaluation of the chemicals in the culture media was made by HPLC. Our results show a wide variation not only with taxonomic groups but also with the species, and with the tested chemicals. On the whole, 4, 7, and 11% of the strains depleted respectively chlortoluron, diuron, and isoproturon, at 50% or over. Rhizoctonia solani was the only strain that depleted each of the 3 substituted phenylureas over 70%, nevertheless, the growth of this fungus was slightly inhibited by diuron. The very fast disappearance of the chemicals from the culture media was only due to biotic phenomena, as no adsorption occurred on the fungal biomass. So, depletion translated a real biodegradation of the tested substrates.

Adsorption↗
PubMed2004

Determination of the microscopic rate constants for the hydrolysis of diuron in soil/water mixture.

A kinetic equation for the analysis of the degradation reaction of xenobiotic molecules in the soil/water mixture has been derived. By means of this equation we have evaluated the microscopic rate constant for the abiotic hydrolysis of the herbicide diuron in the water phase of a soil/water mixture assuming that the reaction occurs only in the water phase and that diuron is reversibly adsorbed by the soil with a higher rate. The soil catalytic capacity on the hydrolysis of diuron was evaluated.

Adsorption↗
PubMed2006

Leaching of atrazine, metolachlor and diuron in the field in relation to their injection depth into a silt loam soil.

A field experiment was conducted on a Calcaric Cambisol soil to study the consequences of the penetration depth and properties of pesticides on the risk of subsequent leaching. Three pesticides with different mobility characteristics and bromide were injected at 30 cm (where soil organic matter (OM) was 2%) and 80 cm (soil OM 0.5%) on irrigated plots without a crop. The migration of injected solutes was assessed for two years by sampling the soil solution using six porous cups installed at 50 and 150 cm depth and by relating solute contents to drainage water flux estimated by the STICS model (Simulateur mulTIdisciplinaire pour les Cultures Standard). Pesticides injected at 30 cm were strongly retained so that no metolachlor or diuron was detected at 50 and 150 cm. The ratio of atrazine peak concentration in the soil solution to concentration in the injected solution (C/C(0)) was 1 x 10(-3) and 0.2 x 10(-3), respectively, at 50 and 150 cm. When injected at 80 cm, (C/C(0)) of atrazine, metolachlor and diuron were 10 x 10(-3), 1 x 10(-3) and 0.3 x 10(-3) at 150 cm, respectively; 1/(C/C(0)) was correlated with K(oc) values reported from databases. The ratio of drainage volume to the amount of water at field capacity in the soil layer between the injection point at 30 cm and the water sampling level (V/V(0)) at 50 and 150 cm was 0.6 and 0.9, respectively, for bromide and 1.6 and 1.0 for atrazine. V/V(0) of the injected solutes at 80 cm was for bromide, atrazine, metolachlor and diuron 0.6, 0.9, 1.2 and 1.7, respectively; pesticide V/V(0) was correlated with K(oc). The retardation factor was a good indicator of migration risk, but tended to overestimate retardation of molecules with high K(oc). Atrazine desorption represented an additional leaching risk as a source of prolonged low contamination. The large variability in soil solution of bromide and pesticide concentrations in the horizontal plane was attributed to flow paths and clods in the tilled soil layer. This heterogeneity was assumed to channel water fluxes into restricted areas and thereby increase the risk of groundwater contamination. The methodology used in the field proves to provide consistent results.

Acetamides↗