Levels Of Diuron Research Articles

Assessing the spatiotemporal occurrence and ecological risk of antifouling biocides in a Brazilian estuary.

Diuron and Irgarol are common antifouling biocides used in paints to prevent the attachment and growth of fouling organisms on ship hulls and other submerged structures. Concerns about their toxicity to non-target aquatic organisms have led to various restrictions on their use in antifouling paints worldwide. Previous studies have shown the widespread presence of these substances in port areas along the Brazilian coast, with a concentration primarily in the southern part of the country. In this study, we conducted six sampling campaigns over the course of 1year to assess the presence and associated risks of Diuron and Irgarol in water collected from areas under the influence of the Maranhão Port Complex in the Brazilian Northeast. Our results revealed the absence of Irgarol in the study area, irrespective of the sampling season and site. In contrast, the mean concentrations of Diuron varied between 2.0ng L-1 and 34.1ng L-1 and were detected at least once at each sampling site. We conducted a risk assessment of Diuron levels in this area using the risk quotient (RQ) method. Our findings indicated that Diuron levels at all sampling sites during at least one campaign yielded an RQ greater than 1, with a maximum of 22.7, classifying the risk as "high" based on the proposed risk classification. This study underscores the continued concern regarding the presence of antifouling biocides in significant ports and marinas in Brazilian ports, despite international bans.

Acute and Chronic Effects of the Antifouling Booster Biocide Diuron on the Harpacticoid Copepod Tigriopus japonicus Revealed through Multi-Biomarker Determination

Diuron, an additive biocide in antifouling paints, is widely employed to curtail the attachment of organisms on submerged surfaces in aquatic structures. Despite the detection of diuron in aquatic ecosystems, information regarding its acute and chronic impacts on aquatic invertebrates, particularly planktonic crustaceans, remains limited. In this study, we analyzed the acute (24 h) and chronic (12 days exposure across three generations) effects of different concentrations of diuron (1/10 of the no observed effect concentration (NOEC), the NOEC, and 1/10 of the lethal concentration 50% (LC50), derived from the 24 h acute toxicity value of 1152 μg L−1) on the harpacticoid copepod Tigriopus japonicus. The acute exposure experiment indicated that the 1/10 LC50 value of diuron significantly reduced the copepod’s feeding rate and acetylcholinesterase activity. In response to the 1/10 LC50 value, the intracellular reactive oxygen species were elevated alongside increased malondialdehyde levels, while the glutathione content was depleted. The enzymatic activities of glutathione S-transferase, catalase, and superoxide dismutase were significantly enhanced by the 1/10 LC50 value, suggesting a proactive role of the antioxidant defense system against oxidative stress. Conversely, the activities of glutathione peroxidase and glutathione reductase enzymes were increased at the NOEC value, while their values were reduced by the 1/10 LC50 value. Chronic exposure to 1/10 NOEC and NOEC values revealed the adverse multigenerational effects of diuron. The second generation exhibited the most sensitivity to diuron, with the NOEC value notably reducing survival rate, body length, nauplius-to-adult development, neonates per brood count, and extending the reproduction period. Taken together, our findings underscore that even sublethal diuron levels can adversely impact copepod populations across generations through intergenerational toxicity.

Tracking Targets of Dynamic Super-Enhancers in Vitro to Better Characterize Osteoclastogenesis and to Evaluate the Effect of Diuron on the Maturation of Human Bone Cells.

Osteoclasts are major actors in the maintenance of bone homeostasis. The full functional maturation of osteoclasts from monocyte lineage cells is essential for the degradation of old/damaged bone matrix. Diuron is one of the most frequently encountered herbicides, particularly in water sources. However, despite a reported delayed ossification invivo, its impact on bone cells remains largely unknown. The objectives of this study were to first better characterize osteoclastogenesis by identifying genes that drive the differentiation of monocyte progenitors into osteoclasts and to evaluate the toxicity of diuron on osteoblastic and osteoclastic differentiation in vitro. We performed chromatin immunoprecipitation (ChIP) against H3K27ac followed by ChIP-sequencing (ChIP-Seq) and RNA-sequencing (RNA-Seq) at different stages of differentiation of monocytes into active osteoclasts. Differentially activated super-enhancers and their potential target genes were identified. Then to evaluate the toxicity of diuron on osteoblasts and osteoclasts, we performed RNA-Seq and functional tests during in vitro osteoblastic and osteoclastic differentiation by exposing cells to different concentrations of diuron. The combinatorial study of the epigenetic and transcriptional remodeling taking place during differentiation has revealed a very dynamic epigenetic profile that supports the expression of genes vital for osteoclast differentiation and function. In total, we identified 122 genes induced by dynamic super-enhancers at late days. Our data suggest that high concentration of diuron () affects viability of mesenchymal stem cells (MSCs) in vitro associated with a decrease of bone mineralization. At a lower concentration (), an inhibitory effect was observed in vitro on the number of osteoclasts derived from monocytes without affecting cell viability. Among the diuron-affected genes, our analysis suggests a significant enrichment of genes targeted by pro-differentiation super-enhancers, with an odds ratio of 5.12 (). Exposure to high concentrations of diuron decreased the viability of MSCs and could therefore affect osteoblastic differentiation and bone mineralization. This pesticide also disrupted osteoclasts maturation by impairing the expression of cell-identity determining genes. Indeed, at sublethal concentrations, differences in the expression of these key genes were mild during the course of in vitro osteoclast differentiation. Taken together our results suggest that high exposure levels of diuron could have an effect on bone homeostasis. https://doi.org/10.1289/EHP11690.

Chronic exposure to environmentally realistic levels of diuron impacts the behaviour of adult marine medaka (Oryzias melastigma).

Diuron, a commonly used herbicide and antifouling biocide, has been frequently detected in seawater. The effects of diuron on fish behaviour are currently poorly understood. Herein, the marine medaka (Oryzias melastigma) was continuously exposed to environmentally realistic levels of diuron from the fertilised egg stage to the adult stage. Behavioural evaluation of adult marine medaka indicated that exposure to diuron increased anxiety in the light-dark test and increased predator avoidance. In addition, diuron exposure significantly reduced aggression, social interaction, shoaling, and learning and memory ability. However, only negligible variations in foraging behaviour and in behaviour in the novel tank test were observed. Marine medaka chronically exposed to diuron also showed decreased levels of dopamine in the brain, and changes were observed in the transcription of genes related to dopamine synthesis, degradation and receptors. Exposure to 5000 ng/L diuron caused significant downregulation of the expression of the genes of tyrosine hydroxylase and monoamine oxidase and significantly upregulated the expression of the genes of the D5 dopaminergic receptor. The relative expression of the D4 dopaminergic receptor was significantly upregulated in the 50, 500 and 5000 ng/L diuron-treated groups. These findings highlight the significant neurotoxic effects of diuron and the extent to which this may involve the dopaminergic system of the brain. More broadly, this study reveals the ecological risk associated with environmentally realistic levels of diuron in marine animals.

Legacy and emerging antifouling biocide residues in a tropical estuarine system (Espirito Santo state, SE, Brazil)

The contamination by antifouling biocide residues (booster biocides - diuron, Irgarol, chlorothalonil, dichlofluanid and DCOIT; butyltin compounds-BTs (TBT, DBT and MBT); and antifouling paint particles-APPs) was appraised in sediments of Vitoria Estuarine System (VES). Even at its historical lower (ΣBTs ≤113 ng Sn g−1 dry wt), the current environmental levels of BTs in areas with a predominance of boatyards still pose a risk to the local biota and human population. DCOIT, among booster biocides, was the most frequently detected, especially in boatyards (≤40 ng g−1 dry wt) and Vitoria Port (64 ng g−1 dry wt), while APPs were also detected mainly in sediments of boatyards (≤5,969 μg g−1 dry wt). Since levels of diuron and DCOIT in APPs were as high as 1,670,000 and 899,000 ng g−1 dry wt, respectively, they are acting as secondary sources of these antifouling biocides. Therefore, VES is threatened by antifouling biocide residues due to the multiple diffuse sources of contamination, showing the need for more efforts on public policies (including temporal trend monitoring studies).

A novel in-situ passive sampling technique in the application of monitoring diuron in the aquatic environment

Abstract Diuron is one of the most common herbicides used in agriculture with long persistence and high toxicity causing a certain hazard to the environment. Thus, this is necessary to control the residue levels of diuron in a natural environment. To achieve this goal, a diffusive gradient in thin-films technique (DGT), as a new method for in-situ sampling, is described in this paper, which can provide the time-weighted average concentration of target compounds in the sampling period. DGT consists of XAD18 resin gel can accumulate up to 73.58 ug diuron in lab conditions and without significant negative performance under varies range of pH (4 to 9), ionic strength (0.001 to 0.5 mmol L−1) and dissolved organic matter(0–20 mg L−1). The string rate of more than 100 rpm indicated the DGT will not likely be affected by flow rate in the aquatic environment. The study successfully indicates the DGT’s performance on diuron, providing a promising technique for future investigation of distribution and occurrence in the natural environment.

Opportunities for coupled electrochemical and ion-exchange technologies to remove recalcitrant micropollutants in water

Micropollutants are found in many waters at concentrations that are concerning for living and environmental systems. They are usually characterised as being persistent and are generally difficult to remove from the water using traditional techniques. In this work, we investigate a treatment technology that couples electrooxidation of micropollutants with subsequent absorption of charged products and remaining compounds through a mixed strong acid and strong base ion exchange resin. The results clearly show that carbon fibre is a promising electrode material. Electrooxidation of the drug Ibuprofen using carbon fibre in a coulombic efficiency of 13 mC/ppm removed 71% of the compound after two hours (down to 29 ppm). The addition of sodium chloride led to a near doubling of the pseudo-first order reaction rate from 1.7 to 3.0 10−4 s−1. A mix of Ibuprofen and the pesticide Diuron showed similarly promising results and while the overall oxidation decreased the positive effect of sodium chloride was present. Strikingly, coupling electrooxidation with a mixed bed ion exchange resin removed both compounds, decreasing levels of Diuron to below the limit of detection (18 ppb) and Ibuprofen down to 0.8 ppm. The approach shows potential as a treatment technology for the removal of complex pollutants in water.

Bioconcentrations of herbicides used in sugarcane crops in tilapia (Oreochromis niloticus) and the risk for human consumption

The practice of intensive herbicide use in the sugarcane industry has a high risk of compromising the quality of the water and the organisms that live there due to losses through runoff, leaching and other processes. In this work, the dynamics of four herbicides present in three different mixtures were evaluated through their incorporation and elimination in the muscle tissue of tilapia (Oreochromis niloticus). The highest mean values of bioconcentration factors were 1.730 for ametryn, 0.891 for tebuthiuron, 0.322 for hexazinone and 4.783 for diuron. Diuron presented the highest risk regarding the consumption of tilapia fillets by the population. However, considering that the fish would reach maximum levels of diuron when exposed to extremely high concentrations, an individual weighing 70 kg would need to ingest approximately 1.5 kg of this food product to surpass the acceptable daily intake of 0.007 mg kg−1 body weight. It was concluded that the risk of injury to the population consuming tilapia fillets from fish exposed to herbicides in water arising from sugarcane activities is very low.According to the risk estimation performed in this work, which is substantiated by the assumptions of the World Health Organization and the International Life Sciences Institute, there is a low risk of injury to the population consuming tilapia fillets from fish exposed to water containing herbicides in concentrations arising from sugarcane activities. However, as the risk was estimated from laboratory conditions, caution should be taken where herbicide applications are carried out with high frequency near water bodies, as the consumption of fish from these areas is quite common.

Simultaneous concentration and chromatographic detection of water pesticides traces using aqueous two-phase system composed of tetrahydrofuran and fructose

Diuron is a pesticide widely used in agriculture to control a variety of weeds, and therefore it is often detected in groundwater and surface water. However, the low levels of diuron in water make its identification and quantification unfeasible, causing great inconvenience in the evaluation of its persistence and environmental impact. In this context, a recovery/concentration method for diuron from water is here proposed based on an aqueous two-phase system (ATPS) composed of tetrahydrofuran (THF) and fructose. The phase diagrams were determined, and subsequently the recovery of the diuron in THF-rich phase was optimized, ranging between 60.05 and 97.26%. In addition, a 200-fold concentration factor of diuron was achieved using a system composed of 12.49 wt% commercial fructose +60.02 wt% THF + 27.49 wt% water (tie-line-length = 66.27). This system permitted single-step recovery, and concentration for diuron and its degradation compounds, and subsequent use of high-pressure liquid chromatography to identify and quantify these pesticides traces in real samples of water collected in the hydrographic basin from the Japaratuba River, in the state of Sergipe, Brazil. The protocol was used as a proof-of-concept, presenting values of 75–1900 ng·L−1 for these organic pollutants. Based on these results, the work proposes an integrated process to quantify diuron and its degradation compounds, besides recycling and reusing the phase-forming components and anti-solvents employed, increasing their detection power.

Comparing the acute sensitivity of growth and photosynthetic endpoints in three Lemna species exposed to four herbicides

An ecological impact assessment of four herbicides (atrazine, diuron, paraquat and simazine) was assessed using the aquatic floating vascular plants, Lemna gibba, Lemna minor and Lemna paucicostata as test organisms. The sensitivity of several ecologically relevant parameters (increase in frond area, root length after regrowth, maximum and effective quantum yield of PSII and maximum electron transport rate (ETRmax), were compared after a 72 h exposure to herbicides. The present test methods require relatively small sample volume (3 mL), shorter exposure times (72 h), simple and quick analytical procedures as compared with standard Lemna assays. Sensitivity ranking of endpoints, based on EC50 values, differed depending on the herbicide. The most toxic herbicides were diuron and paraquat and the most sensitive endpoints were root length (6.0–12.3 μg L−1) and ETRmax (4.7–10.3 μg L−1) for paraquat and effective quantum yield (6.8–10.4 μg L−1) for diuron. Growth and chlorophyll a fluorescence parameters in all three Lemna species were sensitive enough to detect toxic levels of diuron and paraquat in water samples in excess of allowable concentrations set by international standards. CV values of all EC50s obtained from the Lemna tests were in the range of 2.8–24.33%, indicating a high level of repeatability comparable to the desirable level of <30% for adoption of toxicity test methods as international standards. Our new Lemna methods may provide useful information for the assessment of toxicity risk of residual herbicides in aquatic ecosystems.

Distribution of butyltins and alternative antifouling biocides in sediments from shipping and shipbuilding areas in South Korea

The occurrence and distribution of tributyltin (TBT) and alternative biocides were investigated in sediment from semi-enclosed bays, fishing ports, and large commercial harbors in Korea. Extremely high concentration of TBT (55,264ngSn/g) was detected near a large shipyard, even after a total ban on its use in Korea. Diuron was the biocide with the highest detection frequency and concentration levels, followed by Irgarol 1051. Sea-Nine 211 was detected at 3 of 32 stations surveyed. Dichlofluanid, zinc and copper pyrithiones levels were below the detection limits at all the stations surveyed. The relatively high levels of Diuron (9–62.3ng/g) and Irgarol 1051 (1.5–11.5ng/g) were detected in harbor and shipyard areas. Diuron and Irgarol 1051 levels including TBT in sediments from hot spots in Korea exceeded global sediment quality guidelines.

Dose and temporal effects on gene expression profiles of urothelial cells from rats exposed to diuron.

Diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) is a substituted urea herbicide that at high dietary levels (2500 ppm) induces rat urinary bladder hyperplasia after 20 weeks of exposure and neoplasia after 2 years. The effects on the urothelium after short-term exposure have not been described. The present 7-day study evaluated the dose-dependency of urothelial alterations in the urinary bladder using light microscopy, scanning electron microscopy, and genome-wide transcriptional profiling. Male Wistar rats were fed 0, 125, 500, 2500 ppm diuron for 7 days. The urinary bladder and isolated urothelial cells of these animals were processed for microscopic examination and gene expression profiling, respectively. No significant treatment-related morphologic effects were observed. The number of differentially expressed genes (DEGs) in the exposed groups increased with diuron levels. Diuron-altered genes involved in cell-to-cell interactions and tissue organization were identified in all treatment groups. After 7 days of diuron exposure, transcriptional responses were observed in the urothelium in the absence of clear morphologic changes. These morphological findings are different from those observed in a previous study in which 20 weeks of diuron exposure was associated with simple hyperplasia secondary to the persistent cytotoxicity and necrosis associated with continuous cellular regeneration. Comparison of the gene expression profiles of rats exposed to the 2500 ppm carcinogenic diuron dose for 7 days versus 20 weeks revealed few similarities between these two time points at the gene or pathway level. Taken together, these data provide insight into the dose- and temporal-dependent morphological and transcriptional changes associated with diuron exposure that may lead to the development of tumors in the rat urinary bladder.

Contamination of diuron in coastal waters around Malaysian Peninsular

The use of antifouling paints to the boats and ships is one among the threats facing coastal resources including coral reefs in recent decades. This study reports the current contamination status of diuron and its behaviour in the coastal waters of Malaysia. The maximum concentration of diuron was 285ng/L detected at Johor port. All samples from Redang and Bidong coral reef islands were contaminated with diuron. Temporal variation showed relatively high concentrations but no significant difference (P>0.05) during November and January (North-East monsoon) in Klang ports (North, South and West), while higher levels of diuron were detected during April, 2012 (Inter monsoon) in Kemaman, and Johor port. Although no site has shown concentration above maximum permissible concentration (430ng/L) as restricted by the Dutch Authorities, however, long term exposure studies for environmental relevance levels of diuron around coastal areas should be given a priority in the future.

The Influence of Salinity and Matrix Effect in the Determination of Antifouling Biocides in Estuarine Waters of Patos Lagoon (Southern Brazil)

A method for the determination of irgarol and diuron using C18 solid-phase extraction (SPE) and liquid chromatography with electrospray interface tandem mass spectrometry was optimized, validated and applied in estuarine and coastal waters under the influence of Rio Grande harbors (Patos Lagoon). The impact of pre-filtration and salinity in the extraction processes by SPE using C18 and polymeric adsorbents were evaluated and no effect was detected. Recoveries between 95 and 118% (relative standard deviation lower than 20%) and limit of detection and quantification for the method of 1.3 and 4 ng L-1, respectively, were reached for both compounds. The analytical curves presented correlation coefficients higher than 0.99. The matrix effect was lower than 20% for irgarol and between 45.7 and 65.3% for diuron. Diuron and irgarol were detected in 8 and 9 out of 21 sampled sites, respectively, with concentrations ranging from < 1.3 to 20.9 ng L-1. The low concentrations found, together with international restrictions of use and their absence in the four main antifouling paints used in the region, indicate that levels of diuron and irgarol are probably not relevant in this region. In addition, these levels were below of those capable of causing effects on tested species.

Chemical carcinogenesis - mode of action to inform quantitative human risk.

Chemical carcinogenesis - mode of action to inform quantitative human risk.

Describing the environmental fate of diuron in a tropical river catchment

The use of the herbicide diuron on sugarcane fields along the river catchments of the Great Barrier Reef (GBR) in Australia is an issue of concern due to high levels of diuron reported in the GBR lagoon, and has recently led to a restriction on the use of diuron during the 2011/12 wet season. An important question in this context is how much diuron is mobilised from the agricultural area by strong rainfall and floods in the wet season and transferred to the GBR lagoon. We have set up a multimedia chemical fate model for a tropical catchment to describe the fate of diuron within the Tully River catchment, Queensland, Australia. The model includes highly variable rainfall based on meteorological data from the Tully River catchment and a flood water compartment on top of the agricultural soil that is present during times for which floods were reported. The model is driven by diuron application data estimated for the Tully River catchment and is solved for time-dependent diuron concentrations in agricultural soil and seawater. Model results show that on average 25% of the diuron applied every year is transferred to the GBR lagoon with rainwater and flood water runoff. Diuron concentrations estimated for the seawater range from 0.1ng/L to 12ng/L and are in good agreement with concentrations measured in the GBR lagoon. The uncertainty of the diuron concentrations estimated for seawater is approximately a factor of two and mainly derives from uncertainty in the diuron degradation half-life in soil, properties of the soil compartment such as organic matter content, and the speed of the seawater current removing diuron dissolved in seawater from the seawater compartment of the model.

Toxicity of single and combined herbicides on PSII maximum efficiency of an aquatic higher plant, Lemna sp.

The present study examined the effect of single and binary mixtures of four herbicides, namely, atrazine, diuron, simazine and hexazinone on the maximum quantum efficiency of photosynthesis (Fv/Fm) of Lemna sp. after 96 h of exposure. When applied singly, the toxicity ranking of the four herbicides was as follows: diuron>hexazinone>atrazine>simazine. Binary combinations of these toxicants revealed varying inhibition values; for example, the combination of low diuron concentration with both high and low concentrations of hexazinone resulted in a synergistic effect, with mean ratio of inhibition (RI) values ranging from 1.13±0.10 to 1.16±0.08. The combination of diuron with atrazine revealed an additive effect at low diuron levels (0.025 mg L−1) and high atrazine levels (0.1 mg L−1) with an RI value of 1.06±0.07. Our study emphasizes on the utility of combined toxicity models in predicting the toxicological impact of herbicide mixtures on aquatic ecosystems. Overall, this study provides valuable information on the chlorophyll fluorescence of Lemna sp. as a bioanalytical tool for the rapid and inexpensive assessment of photosystem II (PSII) inhibiting herbicide mixtures.

Probabilistic risk assessment of common booster biocides in surface waters of the harbours of Gran Canaria (Spain)

The presence of booster biocides in the aquatic environment has been associated with a risk to non-target species due to their proven toxicity. The aim of the present study was to determine the spatial and temporal distribution of common booster biocides in different harbours of the island of Gran Canaria (Spain) and evaluate, by means of a probabilistic risk assessment (PRA), the ecological risk posed by these compounds. With these objectives, a monitoring campaign was conducted between January 2008 and May 2009, collecting a total of 182 seawater samples. Four common booster biocides (TCMTB, diuron, Irgarol 1051 and dichlofluanid) were monitored. Diuron levels ranged between 2.3 and 203ng/L and Irgarol 1051 between 2.4 and 146.5ng/L. The ecological risk associated with these levels was always low, however, with probabilities of exceeding the 10th percentile of autotroph toxicity below 3.5%.

Effects of the Herbicide Diuron on Cordgrass (Spartina foliosa) Reflectance and Photosynthetic Parameters

Early indicators of salt marsh plant stress are needed to detect stress before it is manifested as changes in biomass and coverage. We explored a variety of leaf-level spectral reflectance and fluorescence variables as indicators of stress in response to the herbicide diuron. Diuron, a Photosystem II inhibitor, is heavily used in areas adjacent to estuaries, but its ecological effects are just beginning to be recognized. In a greenhouse experiment, we exposed Spartina foliosa, the native cordgrass in California salt marshes, to two levels of diuron. After plant exposure to diuron for 28 days, all spectral reflectance indices and virtually all fluorescence parameters indicated reduced pigment and photosynthetic function, verified as reduced CO2 assimilation. Diuron exposure was not evident, however, in plant morphometry, indicating that reflectance and fluorescence were effective indicators of sub-lethal diuron exposure. Several indices (spectral reflectance index ARI and fluorescence parameters EQY, Fo, and maximum rETR) were sensitive to diuron concentration. In field trials, most of the indices as well as biomass, % cover, and canopy height varied predictably and significantly across a pesticide gradient. In the field, ARI and Fo regressed most significantly and strongly with pesticide levels. The responses of ARI and Fo in both the laboratory and the field make these indices promising as sensitive, rapid, non-destructive indicators of responses of S. foliosa to herbicides in the field. These techniques are employed in remote sensing and could potentially provide a link between landscapes of stressed vegetation and the causative stressor(s), which is crucial for effective regulation of pollution.

Rapid Mineralization of the Phenylurea Herbicide Diuron by Variovorax sp. Strain SRS16 in Pure Culture and within a Two-Member Consortium

The phenylurea herbicide diuron [N-(3,4-dichlorophenyl)-N,N-dimethylurea] is widely used in a broad range of herbicide formulations, and consequently, it is frequently detected as a major water contaminant in areas where there is extensive use. We constructed a linuron [N-(3,4-dichlorophenyl)-N-methoxy-N-methylurea]- and diuron-mineralizing two-member consortium by combining the cooperative degradation capacities of the diuron-degrading organism Arthrobacter globiformis strain D47 and the linuron-mineralizing organism Variovorax sp. strain SRS16. Neither of the strains mineralized diuron alone in a mineral medium, but combined, the two strains mineralized 31 to 62% of the added [ring-U-(14)C]diuron to (14)CO(2), depending on the initial diuron concentration and the cultivation conditions. The constructed consortium was used to initiate the degradation and mineralization of diuron in soil without natural attenuation potential. This approach led to the unexpected finding that Variovorax sp. strain SRS16 was able to mineralize diuron in a pure culture when it was supplemented with appropriate growth substrates, making this strain the first known bacterium capable of mineralizing diuron and representatives of both the N,N-dimethyl- and N-methoxy-N-methyl-substituted phenylurea herbicides. The ability of the coculture to mineralize microgram-per-liter levels of diuron was compared to the ability of strain SRS16 alone, which revealed the greater extent of mineralization by the two-member consortium (31 to 33% of the added [ring-U-(14)C]diuron was mineralized to (14)CO(2) when 15.5 to 38.9 mug liter(-1) diuron was used). These results suggest that the consortium consisting of strains SRS16 and D47 could be a promising candidate for remediation of soil and water contaminated with diuron and linuron and their shared metabolite 3,4-dichloroaniline.