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PubMed2006

Recovery of scrap iron metal value using biogenerated ferric iron.

The utility of employing biogenerated ferric iron as an oxidant for the recycling of scrap metal has been demonstrated using continuously growing cells of the extremophilic organism Acidithiobacillus ferrooxidans. A ferric iron rich (70 mol%) lixiviant resulting from bioreactor based growth of A. ferrooxidans readily solubilized target scrap metal with the resultant generation of a leachate containing elevated ferrous iron levels and solubilized copper previously resident in the scrap metal. Recovery of the copper value was easily accomplished via a cementation reaction and the clarified leachate containing a replenished level of ferrous iron as growth substrate was shown to support the growth of A. ferrooxidans and be fully recyclable. The described process for scrap metal recycling and copper recovery was shown to be efficient and economically attractive. Additionally, the utility of employing the E(h) of the growth medium as a means for monitoring fluctuations in cell density in cultures of A. ferrooxidans is demonstrated.

Acidithiobacillus↗
PubMed2005

Sulcotrione versus atrazine transport and degradation in soil columns.

A soil column experiment under outdoor conditions was performed to monitor the fate of 14C-ring-labelled sulcotrione, 2-(2-chloro-4-mesylbenzoyl)cyclohexane-1,3-dione and atrazine, 6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine, in water leachates and in the ploughed horizon of a sandy loam soil. Two months after treatment, the cumulative amounts of herbicide residues leached from the soil were 14.5% and 7% of the applied radioactivity for sulcotrione and atrazine, respectively. Maximum leachate concentrations for each herbicide were observed during the first month following application: 120 and 95 microg litre(-1) for sulcotrione and atrazine respectively. After 2 weeks, 78% of the sulcotrione and atrazine was extractable from the soil, whereas after two months only 10 and 4%, respectively, could be extracted. The maximum sulcotrione content in the first 10 cm of soil was identical with that of atrazine. For both molecules, the content of non-extractable residues was low, being around 15%. Sulcotrione seems to be more mobile than atrazine but the consequences for water contamination are similar since lower doses are used.

Atrazine↗
PubMed2001

Assessment of leaching potential of aldicarb and its metabolites using laboratory studies.

The metabolites of pesticides can contaminate groundwater and pose a risk to human health when this water is used for drinking. This paper reports the results of a laboratory study on aldicarb and its main metabolites, aldicarb sulfone and aldicarb sulfoxide. Aldicarb and its metabolites showed Koc values (6-31) which were lower than that of atrazine (55), indicating that they are very mobile in soil. They are less persistent than atrazine (DT50 = 25 days), with DT50 values from less than 1 day and up to 12 days. Aldicarb behaved as a non-leacher, whereas its metabolites clearly showed the characteristics of leachers. Aged residue leaching experiments showed that aldicarb can occur at high concentrations in the leachate, together with its two metabolites. The leachate composition depends on the incubation time of the parent compound. Aldicarb and its metabolites can form various mixtures in groundwater on the basis of the time elapsing between the application of the insecticide and the first significant rainfall. This study confirms the characteristics of contaminants of aldicarb and especially its metabolites, as reported in the literature.

Aldicarb↗
PubMed2004

Sorption, mineralization and mobility of N-(phosphonomethyl)glycine (glyphosate) in five different types of gravel.

Sorption, mineralization and mobility of glyphosate were studied in six substrates: the five types of gravel most frequently used as surfacing in Denmark and a sandy agricultural soil from Simmelkaer that served as a reference soil. Cumulative mineralization of [methyl-14C]glyphosate in batch studies was highest in coarse gravel, amounting to 14% after 4 days at 30 degrees C and 32% after 31 days. Mineralization was slowest in the sandy reference soil, amounting to only 2% after 31 days. The adsorption coefficient (Kd) of glyphosate in gravel ranged from 62 to 164 litre kg(-1), while that in the sandy reference soil was 410 litre kg(-1). The results indicate that the relatively low Kd in gravel allows a relatively high rate of glyphosate mineralization by the biomass. When Kd is high, in contrast, mineralization is slow. Lowering the temperature to 10 degrees C decreased mineralization by 50% in one of two gravels. The leaching of glyphosate was screened in simple columns of gravel or soil in which precipitation events (20 mm over a 2-h period) were simulated on three occasions, starting either immediately after or 2 days after application of glyphosate. [14C]Glyphosate was applied as a tracer mixed with the commercial product Roundup Garden at the recommended rate of 2.4 kg glyphosate ha(-1), equivalent to 1 microg g(-1) soil. The highest concentration of [14C] compounds (expressed in terms of glyphosate concentration) in leachate from the columns exceeded 1300 microg litre(-1), and was detected in rounded gravel after the first rain event. No glyphosate was detected in leachate from the sandy reference soil.

Adsorption↗
PubMed2003

A practical and user-friendly toxicity classification system with microbiotests for natural waters and wastewaters.

Various types of toxicity classification systems have been elaborated by scientists in different countries, with the aim of attributing a hazard score to polluted environments or toxic wastewaters or of ranking them in accordance with increasing levels of toxicity. All these systems are based on batteries of standard acute toxicity tests (several of them including chronic assays as well) and are therefore dependent on the culturing and maintenance of live stocks of test organisms. Most systems require performance of the bioassays on dilution series of the original samples, for subsequent calculation of L(E)C50 or threshold toxicity values. Given the complexity and costs of these toxicity measurements, they can only be applied in well-equipped and highly specialized laboratories, and none of the classification methods so far has found general acceptance at the international level. The development of microbiotests that are independent of continuous culturing of live organisms has stimulated international collaboration. Coordinated at Ghent University, Belgium, collaboration by research groups from 10 countries in central and eastern Europe resulted in an alternative toxicity classification system that was easier to apply and substantially more cost effective than any of the earlier methods. This new system was developed and applied in the framework of a cooperation agreement between the Flemish community in Belgium and central and eastern Europe. The toxicity classification system is based on a battery of (culture-independent) microbiotests and is particularly suited for routine monitoring. It indeed only requires testing on undiluted samples of natural waters or wastewaters discharged into the aquatic environment, except for wastewaters that demonstrate more than 50% effect. The scoring system ranks the waters or wastewaters in 5 classes of increasing hazard/toxicity, with calculation of a weight factor for the concerned hazard/toxicity class. The new classification system was applied during 2000 by the participating laboratories on samples of river water, groundwaters, drinking waters, mine waters, sediment pore waters, industrial effluents, soil leachates, and waste dump leachates and was found to be easy to apply and reliable.

Animals↗
PubMed2006

Leaching and toxicity behavior of coal-biomass waste cocombustion ashes.

Land disposal of ash residues, obtained from the cocombustion of Greek lignite with biomass wastes, is known to create problems due to the harmful constituents present. In this regard, the leachability of trace elements from lignite, biomass, and blends cocombustion ashes was investigated by using the Toxicity Characteristic Leaching Procedure (TCLP) of the US Environmental Protection Agency (US EPA). In this work, the toxicity of the aqueous leachates and the concentrations of the metals obtained from the leaching procedure were measured using the Microtox test (Vibrio fischeri) and inductive coupled plasma-atomic emission spectrometer (ICP-AES), respectively. The toxic effects of most leachates on Vibrio fischeri were found to be significantly low in both 45% and 82% screening test protocols. However, the liquid sample originating from olive kernels fly ash (FA4) caused the highest toxic effect in both protocols, which can be attributed to its relatively high concentrations of As, Cd, Co, Cu, Mn, Ni, and Zn.

Aliivibrio fischeri↗
PubMed1994

The environmental risks of industrial waste disposal: an experimental approach including acute and chronic toxicity studies.

The toxicity of 15 leachates of various solid industrial wastes accepted in an engineered landfill has been studied. A cost-effective battery of tests allowing evaluation of acute and chronic toxicity, as well as genotoxicity, and investigations on different trophic levels in the aquatic environment has been used. Acute toxicity was tested on bacteria (Microtox assay with Photobacterium phosphoreum) and microcrustaceans (Daphnia magna immobilization assay). A growth inhibition test of microalgae was carried out on Raphidocelis subcapitata. A 28-day chronic test with Daphnia magna was used to detect effects on reproduction. Genotoxicity was evaluated by means of the Ames test conducted on the crude aqueous phase and also on the concentrated fractions of water-extractable micropollutants (liquid-liquid and freeze-dried extracts). Chemical analyses of leachates were carried out simultaneously. The toxicity varied greatly between the different wastes. Toxic effects were observed in the short and/or in the long term. Four samples were potentially genotoxic. In most cases, toxicity registered could not be correlated with results of the chemical analyses. This study demonstrates the usefulness of associating a toxicological monitoring with chemical analyses in waste management.

Animals↗
PubMed1999

Ecotoxicological characterization of energetic substances using a soil extraction procedure.

The acetonitrile-sonication extraction method (US EPA SW-846 Method 8330) and aquatic-based toxicity tests were used on laboratory and field samples, to characterize the ecotoxicity of soils contaminated with energetic substances. Spiked soil studies indicated that 2,4, 6-trinitrotoluene (TNT)-dependent soil toxicity could be measured in organic extracts and aqueous leachates using the 15-min Microtox (Vibrio fischeri, IC50=0.27 to 0.94 mg TNT/liter incubation medium) and 96-h Selenastrum capricornutum growth inhibition (IC50=0.62 to 1. 14 mg/liter) toxicity tests. Analyses of leachates of composite soil samples [containing TNT and some TNT metabolites, 1,3,5-trinitro-1,3, 5-triazacyclohexane (RDX), and 1,3,5,7-tetranitro-1,3,5, 7-tetrazacyclooctane (HMX)] from an explosives manufacturing facility, indicated toxicities similar to those found in the TNT-spiked soil studies and pure TNT in solution, and suggested that TNT was the major toxicant. Using TNT as a model toxicant in soils having different moisture contents (20% vs dry) and textures (sandy vs clayey-sandy) but similar organic matter content (3-4%), multi-factorial analyses of Microtox test data revealed that these soil factors significantly influenced the TNT extractability from soil and subsequent toxicity measurements. Taken together, data indicate that the modified Method 8330 may be used in conjunction with ecotoxicity tests to reflect the toxic potential of soils contaminated with energetic substances.

Acetonitriles↗
PubMed2002

Integrated environmental monitoring and simulation system for use as a management decision support tool in urban areas.

Leachates are generated as a result of water or other liquid passing through waste at a landfill site. These contaminated liquids originate from a number of sources, including the water produced during the decomposition of the waste as well as rain-fall which penetrates the waste and dissolves the material with which it comes into contact. The penetration of the rain-water depends on the nature of the landfill (e.g. surface characteristics, type and quantity of vegetation, gradient of layers, etc). The uncontrolled infiltration of leachate into the vadose (unsaturated) zone and finally into the saturated zone (groundwater) is considered to be the most serious environmental impact of a landfill. In the present paper the water flow and the pollutant transport characteristics of the Ano Liosia Landfill site in Athens (Greece) were simulated by creating a model of groundwater flows and contaminant transport. A methodology for the model is presented. The model was then integrated into the Ecosim system which is a prototype funded by the EU, (Directorate General XIII: Telematics and Environment). This is an integrated environmental monitoring and modeling system, which supports the management of environmental planning in urban areas.

Cities↗
PubMed1982

Movement and identification of a creosote-derived PAH complex below a river pollution point source.

High pressure liquid chromatography was used to determine the identity of a black, oily leachate seeping into a spring-fed river. The leachate was identified as creosote by comparing a sample of the material to a sample of commercial creosote. As creosote contains a complex mixture of polynuclear aromatic hydrocarbons (PAH), the direct introduction of creosote into a stream system provided an opportunity to study the kinetics of these hydrocarbons as sediment contaminants below the creosote source. Concentrations of PAH, calculated on the basis of the amounts of organic matter contained in the sediments, declined rapidly below the point source in a form readily approximated by double exponential equations. An important aspect of the pattern of decline encountered was that concentrations tended to become asymptotic. As a result, the river's sediments became contaminated over a considerable distance.

Benzo(a)pyrene↗
PubMed2002

The toxicity and fate of phenolic pollutants in the contaminated soils associated with the oil-shale industry.

Phenol, cresols, dimethylphenols and resorcinols considered major pollutants in the oil-shale semi-coke dump leachates (up to 380 mg phenols/L) that contaminate the surrounding soils and pose a threat to the groundwater in the North-East of Estonia. However; despite high residual concentrations of polyaromatic hydrocarbons (PAHs) and oil products in these soils, the concentration of phenols (especially their water-extractable fraction) was low, not exceeding 0.7 mg/kg dwt. The aim of the current study was to evaluate the role of biodegradation and aging on the decrease of hazard caused by phenolic pollution. The extractability of phenols (phenol, cresols, dimethylphenols and resorcinols) and their biodegradability by the microbial population was studied in the 13 soils sampled from the Estonian oil-shale region, territories of former gas stations, and from presumably non-polluted areas. Phenol, 5-methylresorcinol, p-cresol and resorcinol could be considered easily degradable in the soils as the microbial populations from majority of the soils studied were able to grow on mineral medium supplemented with these phenols as a single source of carbon. 2,3- and 2,4- and 3,4-dimethylphenols could be considered less easily biodegradable. The semi-coke dump leachate polluted soil (containing no dibasic phenols, 43 mg of monobasic phenols, 1348 mg of oil products and 35 mg of PAHs per g dwt) was analyzed chemically (HPLC) and toxicologically (Flash-Assay using Vibrio fischeri) for the leaching of phenols during shaking of soil-water slurries for 24 h. Only 5.8% of the total concentration of phenols was water-extractable, whereas about 50% of the leached amount was biodegraded by the soil microorganisms. Phenol and cresols were biodegraded by 80%, but the concentration of dimethylphenols practically did not change. The pollutants (measured as total water-extractable toxicity) were desorbed from the soil particles by the 8th h of extraction, whereas the toxicity of the aqueous phase continued to increase, probably due to the formation of toxic metabolites. The concentration of water-extractable phenols was too low to explain the toxicity of the extract. Also the impact of PAHs and oil products was excluded. Thus, the relatively low concentration of phenols in the oil-shale region soils is most probably the reflection of both natural attenuation and pollution aging. Therefore, the impact of phenolic compounds to the net bioavailable hazard is probably not so remarkable as has been considered. The actual pollutants causing the soils from the oil-shale region, however, need to be elucidated.

Biodegradation, Environmental↗
PubMed2005

Toxicity identification evaluation of five metals performed with two organisms (Daphnia magna and Lactuca sativa).

When trying to identify the main toxicants in effluents, natural waters, sediments, soil leachates, and leachates from products, the Toxicity Identification Evaluation (TIE) procedure has proven useful. To enhance the use of this procedure for soil, sewage, and sediment samples, we wanted to evaluate this TIE procedure, regarding metal toxicity, for the 96-h root elongation test performed with Lactuca sativa (lettuce) seeds. We also wanted to evaluate the effect of TIE treatment on the toxicity of Mn and Fe to Daphnia magna. Bioassays were performed with Daphnia magna (48-h immobility) and lettuce seeds (96-h root elongation) to determine the effect concentrations for both organisms of Ag, Cu, Fe, Mn, and Zn. The TIE was then performed at the determined Daphnia 48-h EC(84) and Lactuca 96-h EC(50) for each metal. Our results showed that the order of the metal toxicity was Ag>Cu>Zn>Fe>Mn, for Daphnia and Ag = Zn = Fe = Cu > Mn for lettuce seeds. We also found that toxicity of the metals for Daphnia magna was reduced according to the prevailing knowledge regarding Cu, Zn, and Ag. However, the toxicity of Ag and Cu for Daphnia was also reduced by filtration through a C18 resin. Toxicity of Mn and Fe was reduced by filtration through a CM resin and increase of pH. For lettuce seeds, toxicity of the metals was reduced by the same treatments as for Daphnia magna with the exception of EDTA addition, which did not affect Cu toxicity to lettuce seeds. No effects were found for filtration through a C18 resin. We suggest that the TIE procedure using lettuce seeds can be used in toxicity identification of metals. However, the effects of pH manipulations were often stronger with lettuce and should be interpreted with care.

Animals↗
PubMed1997

The effect of low temperature (5-29 degrees C) and adaptation on the methanogenic activity of biomass.

The influence of low temperature (5-29 degrees C) on the methanogenic activity of non-adapted digested sewage sludge and on temperature/leachate-adapted biomass was assayed by using municipal landfill leachate, intermediates of anaerobic degradation (propionate) and methane precursors (acetate, H2/CO2) as substrates. The temperature dependence of methanogenic activity could be described by Arrhenius-derived models. However, both substrate and adaptation affected the temperature dependence. The adaptation of biomass in a leachate-fed upflow anaerobic sludge-blanket reactor at approximately 20 degrees C for 4 months resulted in a sevenfold and fivefold increase of methanogenic activity at 11 degrees C and 22 degrees C respectively. Both acetate and H2/CO2 were methanized even at 5 degrees C. At 22 degrees C, methanogenic activities (acetate 4.8-84 mM) were 1.6-5.2 times higher than those at 11 degrees C. The half-velocity constant (Ks) of acetate utilization at 11 degrees C was one-third of that at 22 degrees C while a similar Ki was obtained at both temperatures. With propionate (1.1-5.5 mM) as substrate, methanogenic activities at 11 degrees C were half those at 22 degrees C. Furthermore, the residual concentration of the substrates was not dependent on temperature. The results suggest that the adaptation of biomass enables the achievement of a high treatment capacity in the anaerobic process even under psychrophilic conditions.

Acetates↗
PubMed1999

Decontamination of Fly Ash and Used Lime from Municipal Waste Incinerator Using Thiobacillus ferrooxidans.

/ The purification of incinerator gases produces large quantities of fly ash and used lime [a combination referred to as air pollution control residues (APCR)], both of which contain elevated levels of metals. This paper describes biological solubilization assays utilizing Thiobacillus ferrooxidans to leach metals from APCR to render them nonhazardous. The multistage solubilization process involves an alkaline aqueous phase that removes some Pb. In the second phase, the APCR are acidified to pH 4 with H(2)SO(4), then inoculated with a bacterial culture that has been acclimated in the presence of 2% Fe (FeCl(3)). Several rinses and decantings achieve removal of the leachable metals. The final step involves the addition of Ca(H(2)PO(4))(2) and an increase in the treatment pH prior to the final filtration. Viability of thiobacilli in APCR was poor. Despite this problem, the removal of Pb was 35.9%, 46.0%, and 68.7% (for APCR containing 1594, 3026, and 5038 mg Pb/kg, respectively), which demonstrates greater metal removal with increased APCR contamination. Zn removal varied from 68.2% (8273 mg Zn/kg APCR) to 79.5% (16,873 mg Zn/kg APCR), which was positively correlated to the level of residue contamination, whereas Cu was removed in the proportions of 26.9% (495 mg Cu/kg APCR) to 68.2% (465 mg Cu/kg APCR). Cadmium removal appeared to be independent of the level of Cd in the APCR; Cd was removed to the greatest degree, with a variation of 92.0% (129 mg Cd/kg APCR) to 94.7% (267 mg Cd/kg APCR). The treated APCR were tested using four different leachate tests. The APCR released 43 mg Pb/liter during contact with water, and 7.40 mg Cd/liter during TCLP [the toxicity characterization leaching procedure of the United States Environmental Protection Agency (US EPA)]. After biological treatment, the leachate from TCLP was within the acceptance criteria of the US EPA, if the pH of the APCR was increased to pH 5 after the biological treatment. In the case of the Transport Canada leaching test, a betterment of the process is required in order to satisfy the stringent regulatory level of 0.5 mg Cd/liter (0.68 and 0.57 mg/liter).KEY WORDS: Thiobacilli; Metals removal; Fly ash; Incinerator; Hazardous waste.http://link.springer-ny.com/link/service/journals/00267/bibs/24n4p517.html</HEA

Journal Article↗
PubMed2003

Growth and survival of seedlings of native plants in an impoverished and highly disturbed soil following inoculation with arbuscular mycorrhizal fungi.

We investigated whether arbuscular mycorrhizas influenced growth and survival of seedlings in an extremely impoverished and highly disturbed soil. Seedlings of four plants species native to the site were either inoculated with native sporocarpic arbuscular mycorrhizal (AM) fungi or fertilised prior to transplanting, and followed over 86 weeks at the site. One treatment was also irrigated with N-rich leachate from the site. In a laboratory experiment, seedlings were fertilised with excess P for 6 weeks, and location of the P store determined. Growth and survival of AM and fertilised seedlings were similar at the site. Inoculated mycorrhizal fungi and roots appeared to extend into the surrounding soil together. P concentration in leaves of all plants was extremely low. Irrigation with leachate increased growth of seedlings. In the laboratory experiment, significantly more P was stored in roots than shoots. We suggest that successful revegetation of extremely disturbed and impoverished sites requires selection of mycorrhizal fungi and plants to suit the edaphic conditions and methods of out-planting.

Cupressaceae↗
PubMed2006

Modelling MSW decomposition under landfill conditions considering hydrolytic and methanogenic inhibition.

A landfill typically progresses through a series of microbial degradation phases, in which hydrolysis, production and consumption of fermentation products, such as fatty acids, and methane formation play important roles. For ultimate degradation of the waste, stable methanogenic conditions have to be attained, and maintained for sufficient time. Using experimental data from 100-L landfill simulation reactors containing municipal solid waste from a residential area, a distributed model, which accounts for vertical water flow, was developed. As a first step, the waste was divided into two fractions: readily degradable and recalcitrant waste. Secondly, the general hydrolysis of the recalcitrant waste was accounted for by including a specific, well-defined chemical substance in the model that generally occurs in Municipal Solid Waste (MSW) and is hydrolysed before its further degradation to methane. For this purpose we chose diethyl phthalate and its hydrolysis product monoethyl phthalate, for which leachate data are available from the reactors. The model indicated that inhibition of the hydrolytic and methanogenic processes occurred during the acidogenic phase and that it could be overcome either by improving the chemical environment or by the complete oxidation of the inhibiting, i.e. the easily degraded, fraction of the waste. The generality of the model was confirmed by the patterns of the phthalate di- and monoester transformations obtained. The validity of the model was further confirmed using experimental data from parallel reactors, which were subjected to either leachate exchange with an already methanogenic reactor or to initial aeration to force the reactor into stable methanogenic conditions.

Biodegradation, Environmental↗
PubMed2006

Selected ectomycorrhizal fungi of black spruce (Picea mariana) can detoxify phenolic compounds of Kalmia angustifolia.

Allelopathy has been implicated as a factor contributing toward failure of black spruce (Picea mariana) regeneration in Kalmia angustifolia-dominated sites in eastern Canada. Several phenolic acids of Kalmia origin inhibit primary root growth of black spruce. We tested the hypothesis that some well-adapted conifer ectomycorrhizae can degrade and detoxify water-soluble phenolic compounds produced by Kalmia and use the degraded products as a carbon source to stimulate growth. We found that hyphal growth of Paxillus involutus, a common ectomycorrhizal fungus of black spruce, was stimulated by water leachates of Kalmia leaf and litter. An equimolar mixture of three phenolic acids (ferulic, o-coumaric, and o-hydroxyphenylacetic acid), commonly found in Kalmia, had no negative effects on fungal growth at 1 mM concentration. The o-hydroxyphenylacetic (o-HPA) acid, which is known to be toxic to black spruce, was found to stimulate the growth of Laccaria laccata, L. bicolor, and P. involutus (isolates 211804 and 196554) by 38.4, 29.3, 25.0, and 18.9%, respectively, at 1 mM. Pure ferulic, o-coumaric, and o-HPA acids were degraded by 100, 98, and 79.5%, respectively, within 10 d in the presence of P. involutus 211804. However, L. laccata could not tolerate high concentrations of the Kalmia leachates. P. involutus and L. bicolor used o-HPA acid as a carbon source when cultured in noncarbon nutrient medium. The 0.5 and 0.2 mM o-HPA acid inhibited the root growth of black spruce. However, after solutions had been exposed to a culture of P. involutus, they had no significant effect on seedling growth of black spruce. We concluded that some ectomycorrhizal fungi, such as P. involutus and L. bicolor, are able to degrade Kalmia phenolics. Our findings point to a mechanism by which ectomycorrhizal species can control species interactions in higher plants by changing the rhizosphere chemistry.

Canada↗
PubMed1990

Fate of [14C]monolinuron in potatoes and soil under outdoor conditions.

[phenyl-14C]Monolinuron was applied (2.5 and 1.9 kg/ha) to the soil surface of an outdoor lysimeter in two successive years: then, potatoes were grown. Total recovery of 14C in soil, plants, and leached water was about 55% (of 14C applied) after the first growing period and about 43% after the second growing period. Radioactivity in soil contained 77.1% (based on total 14C recovered in soil) bound residues, 15% monolinuron, and the following conversion products: N-(4-hydroxyphenyl)-N'-methoxy-N'-methylurea, N-(4-chlorophenyl)-N'-methylurea. N-(4-chlorophenyl)methylcarbamate, N-(4-chlorophenyl)-N-methyl-methylcarbamate, and 4-chloroformanilide. The leachate contained 0.8% (based on total 14C recovered in leachate) N-(4-hydroxyphenyl)-N'-methoxy-N'-methylurea. Potato plants contained 0.106 mg/kg radioactive residues in peeled tubers after one growing period and 15.94 mg/kg in the tops; after two growing periods, peeled tubers contained 0.091 mg/kg and tops contained 18.87 mg/kg radioactive residues. These residues consisted of bound 14C (57.9% of total 14C recovered in plants), N-(4-hydroxyphenyl)-N'-methoxy-N'-methylurea, N-(4-chlorophenyl)-N'-methylurea, N-(4-chlorophenyl)methylcarbamate, N-(4-chlorophenyl)-N-methyl-methylcarbamate, and 4,4'-dichlorozobenzene.

Biodegradation, Environmental↗