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PubMed2005

Hydroxyl free radical reactivity toward aqueous chlorinated phenols.

Second-order kinetic constants (k(OH,S)) for the hydroxyl free radical attack on a series of nine chlorophenols (2-chlorophenol, 2,4-dichlorophenol, 2,5-dichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, 2,3,5,6-tetrachlorophenol, 2,3,4,5-tetrachlorophenol, 2,3,4,6-tetrachlorophenol, and pentachlorophenol) in aqueous solution were determined by means of the competitive kinetics method. Experimental values ranged from 3.5 x 10(09)M(-1)s(-1) for pentachlorophenol to 8.2 x 10(09)M(-1)s(-1) for 2-chlorophenol. A general trend of lower kinetic constant values with higher degree of chlorination was observed and tested with four different correlations using Hammett's sigma values, the number of chlorine substituents on the aromatic ring, and estimated diffusion coefficients. These correlations were statistically significant (alpha=0.01), although the regression coefficients were moderate (R(2)<0.6). Statistical analysis indicated that all correlations were equally valid. This report includes second-order kinetic constants not previously reported for six chlorophenols, and also provides the means to estimate constants for other chlorophenols for which no experimental data are available.

Chlorine↗
PubMed1983

High-performance liquid chromatographic analysis of chlorophenols in cardboard food containers and related materials.

A technique has been developed for the extraction of a clean concentrate of chlorophenols from cardboard food containers and adhesives of the type used in their manufacture. A simple, reversed-phase, isocratic high-performance liquid chromatographic (HPLC) system employing an optimised mobile phase permitted the separation of nineteen different phenols. The use of a carefully selected internal standard permitted the estimation of (sub) parts per million levels of pentachlorophenol, 2,3,4,6-tetrachlorophenol and 2,4,6-trichlorophenol in several samples of adhesives and various sections of cardboard food containers. Pentachlorophenol (50 ng) and 2,4,6-trichlorophenol (20 ng) gave significant HPLC peaks, readily permitting their detection in parts per billion from 100-g samples.

Adhesives↗
PubMed1987

Mechanism of formation of polychlorinated dibenzo-p-dioxins produced on municipal incinerator flyash from reactions of chlorinated phenols.

All incinerators burning municipal waste produce chlorinated dioxins. The mechanism by which these compounds are formed is unknown. Experiments were performed that show these compounds can be produced from known precursors by surface catalysed reactions on the flyash particulates present in the incineration process. A full range of the tetra- through octachlorinated dibenzo-p-dioxins were produced from 13C-labelled pentachlorophenol and two trichlorophenols on the surface of flyash from an Ontario municipal incinerator that had been previously freed from organic material. A simple flow-tube apparatus at 300 degrees C under a 10-ml/min nitrogen flow was used for the experiments. The use of 13C-labelled pentachlorophenol gave a direct measure of the extent of the catalytic reactivity of the flyash surface. Much lower amounts of chlorinated dioxins were produced in similar experiments with flyash from a modern Japanese incinerator whose effluents are normally extremely low in these compounds. Only small amounts of octachlorodioxin, the thermal condensation product expected, were formed using ground firebrick or an empty flow-tube for the reactive surface. These results indicate that the flyash surface has constituents and properties that promote the production of chlorinated dioxins from chlorinated phenols and support the catalyzed surface reaction mechanism previously proposed.

Carbon↗
PubMed2002

Concentration of chlorophenols in water with sodium dodecylsulfate-gamma-alumina admicelles for high-performance liquid chromatographic analysis.

Chlorophenols in water were sorbed onto sodium dodecylsulfate (SDS)-alumina (gamma-form) admicelles. The extent of sorption increased with increasing amount of SDS and decreasing solution pH. Conditions for good recovery were obtained when 100 mg SDS and 1.5 g alumina was used at pH 2. However, the yield decreased with a further increase in the SDS concentration due to the formation of normal SDS micelles. The extent of sorption also increased with increasing hydrophobicity of the chlorophenol, indicating that hydrophobic interactions predominate for the collection of analytes. When a cartridge column filled with admicelles was used, >90% of tetrachlorophenol and pentachlorophenol in 200 ml of water samples were rapidly recovered. The sorbed analytes were eluted with 1 ml acetonitrile. The accuracy and precision of the present method were demonstrated for the HPLC analysis with ultraviolet (290 nm) detection of microg l(-1) levels of tetrachlorophenol and pentachlorophenol in river water samples.

Aluminum Oxide↗
PubMed2002

Direct determination of chlorophenols in landfill leachates by solid-phase micro-extraction-gas chromatography-mass spectrometry.

Landfill leachates represent a serious environmental concern with regard to trace priority pollutants introduced into the aquatic environment. From the analytical point of view, they constitute complex matrices because of their high organic matter content and competition with the trace analytes in the extraction procedure. Although the use of SPME to extract chlorophenols in leachates has already been described in several publications, the limited number of chlorophenols restricts this analysis field of application. This paper presents a new analytical methodology to determine 13 chlorophenols and phenol by SPME-GC-MS in landfill leachates. The overall analysis was performed in 90 min and the detection limits range from 0.005 microg/l (pentachlorophenol) to 2.5 microg/l (phenol). Reproducibility, expressed by the coefficient of variation of repeated extractions at different concentration levels of the analytes, was on average inferior to 10%. Recovery, evaluated by standard addition to leachates, was 86.2% on average. Pentachlorophenol, 2,3,4,5-tetrachlorophenol and 2,3,4,6-tetrachlorophenol were the sole analytes detected at nanogram level in the landfill leachates analysed.

Chlorophenols↗
PubMed2003

Competition for oxygen by iron and 2,4,6-trichlorophenol oxidizing bacteria in boreal groundwater.

Kinetics of simultaneous iron and 2,4,6-trichlorophenol (TCP) oxidation by groundwater enriched cultures were studied in order to reveal the competition for oxygen in aerobic in situ bioremediation of boreal groundwater. Chemical iron oxidation at near neutral pH in synthetic groundwater depended by the first order on the concentrations of ferrous iron and dissolved oxygen and by the second order on pH. The chemical iron oxidation rate constant was on average 2.2 x 10(13)mol(-2)L(2)atm(-1)min(-1). Chemical iron oxidation was insignificantly affected by natural organic matter, 2,4,6-tri-, 2,3,4,6-tetra- or pentachlorophenol in groundwater. Biological oxidation of iron followed zero-order kinetics. At pH of 6.3 and dissolved oxygen (DO) concentration of 11.5 mgL(-1), the rate of biological iron oxidation was 3.8 x 10(-4)mmolL(-1)min(-1) and up to one order of magnitude higher than the chemical oxidation rate, 5.2 x 10(-6) mmolL(-1)min(-1). Biological oxidation of iron was completely inhibited by pentachlorophenol at 23 micro mol-1. With a groundwater enriched culture, oxygen was consumed at higher rates by 2,4,6-TCP oxidizers (2.5-7.6 x 10(-5)mmolDOL(-1)min(-1)) than the iron oxidizing bacteria (0.8-3.1 x 10(-5) mmolDOL(-1)min(-1)) at both low and saturated DO-concentrations. The results indicate that in situ iron oxidation is predominantly biogenic in the studied boreal aquifer. 2,4,6-TCP degrading bacteria consumed DO at higher rates than the iron oxidizing bacteria and thereby, favour bioremediation of the polychlorophenol contaminated groundwater.

Bacteria↗
PubMed2003

Endocrine disrupting chemicals: interference of thyroid hormone binding to transthyretins and to thyroid hormone receptors.

We examined the effects of industrial, medical and agricultural chemicals on 3,5,3'-L-[125I]triiodothyronine ([125I]T(3)) binding to transthyretins (TTRs) and thyroid hormone receptors (TRs). Among the chemicals investigated diethylstilbestrol (DES) was the most powerful inhibitor of [125I]T(3) binding to chicken and bullfrog TTR (cTTR and bTTR). Inhibition of [125I]T(3) binding was more apparent in cTTR than bTTR. Scatchard analysis revealed DES, pentachlorophenol and ioxynil as competitive inhibitors of [125I]T(3) binding to cTTR and bTTR. However, cTTR's affinity for the three chemicals was higher than its affinity for T(3). A miticide dicofol (10(-10)-10(-7) M) activated [125I]T(3) binding to bTTR up to 170%. However, at 4x10(-5) M it inhibited [125I]T(3) binding by 83%. Dicofol's biphasic effect upon [125I]T(3) binding was not detected in TTRs from other species. DES and pentachlorophenol, in the presence of plasma, increased cellular uptake of [125I]T(3) in vitro, by displacing [125I]T(3) from its plasma binding sites. These chemicals did not, however, affect the association of cTTR with chicken retinol-binding protein. All chemicals investigated had little or no influence on [125I]T(3) binding to chicken TR (cTR) and bullfrog TR (bTR). Several endocrine disrupting chemicals that were tested interfered with T(3) binding to TTR rather than to TR. Binding of the endocrine disrupting chemicals to TTR may weaken their intrinsic effects on target cells by depressing their free concentrations in plasma. However, this may affect TH homeostasis in vivo by altering the free concentrations of plasma THs.

Animals↗
PubMed2003

Serum albumin binding at cytotoxic concentrations of chemicals as determined with a cell proliferation assay.

The aim of the present study was to measure the influence of albumin binding on cytotoxic concentrations of chemicals and to determine binding parameters which can be used for quantitative in vitro-in vivo extrapolations. Protein binding parameters were determined from cytotoxic potencies measured with Balb/c 3T3 cells cultured in the presence of 18 and 600 microM bovine serum albumin (BSA). A subset of 27 chemicals from the Multicenter Evaluation of In Vitro Cytotoxicity (MEIC) project was investigated. At 18 microM BSA the EC(50)-values ranged from 2.54 microM (As(III)) to 527 mM (ethylene glycol). Increasing the BSA concentration either decreased the cytotoxic potency (12 compounds) by factors up to 34 (pentachlorophenol), had no effect (14 compounds), or increased the cytotoxicity (paraquat). Calculated molar ratios of binding ranged from 0.05 (Hg(2+)) to 4.8 moles per mole albumin (acetylic salicylic acid). At 18 microM BSA fractional binding of most of these compounds was low (<25%) but increased up to > or =90% (hexachlorophene, mercuric chloride, thioridazine, pentachlorophenol) at 600 microM BSA. The results obtained in general were compatible with available protein binding data and can be used to calculate equipotent concentrations of chemicals in biological systems containing different albumin concentrations.

3T3 Cells↗
PubMed2000

Sonochemical degradation of chlorophenols in water

Sonochemical degradation of dilute aqueous solutions of 2-, 3- and 4-chlorophenol and pentachlorophenol has been investigated under air or argon atmosphere. The degradation follows first-order kinetics in the initial state with rates in the range 4.5-6.6 microM min-1 under air and 6.0-7.2 microM min-1 under argon at a concentration of 100 microM of chlorophenols. The rate of OH radical formation from water is 19.8 microM min-1 under argon and 14.7 microM min-1 under air in the same sonolysis conditions. The sonolysis of chlorophenols is effectively inhibited, but not completely, by the addition of t-BuOH, which is known to be an efficient OH radical scavenger in aqueous sonolysis. This suggests that the main degradation of chlorophenols proceeds via reaction with OH radicals; a thermal reaction also occurs, although its contribution is small. The addition of appropriate amounts of Fe(II) ions accelerates the degradation. This is probably due to the regeneration of OH radicals from hydrogen peroxide, which would be formed from recombination of OH radicals and which may contribute a little to the degradation. The ability to inhibit bacterial multiplication of pentachlorophenol decreases with ultrasonic irradiation.

Journal Article↗
PubMed2003

Dioxins in aquatic sediment and soil in the Kanto region of Japan: major sources and their contributions.

Major sources of dioxins (tetra- to octa-chlorinated dibenzo-p-dioxins and dibenzofurans) were quantitatively identified, and the contributions of each source were estimated in aquatic surface sediment and soil in the Kanto region of Japan, where a major part of the municipal, industrial, and agricultural activities in Japan take place. Detailed chromatographic peak-specific data corresponding to all dioxin compounds were used throughout the analysis to achieve source specificity. Four major sources were identified by using principal component analysis. Three of them were combustion processes, impurities in pentachlorophenol, and impurities in the diphenyl ether herbicide CNP. One, characterized by polychlorinated dibenzo-p-dioxins with 1,2,6,9-chlorine substitution, remained unattributed to any known source or transformation process. The composition of the unattributed source resembled those reported in sediment samples free from anthropogenic impacts. Contributions from the four major sources were estimated by using a mass balance receptor model, and the source contributions to each homologue varied among samples. Tokyo Bay sediment was characterized by the highest relative contribution from pentachlorophenol impurities in the region. The unattributed source contribution was most prominent in the Lake Kasumigaura sediment. The results indicated considerable contributions in aquatic surface sediment in the studied region from dioxin impurities in herbicides used in the past.

Agriculture↗
PubMed2003

Toxicity of a complex mixture of atmospherically transported pesticides to Ceriodaphnia dubia.

The presence of several anthropogenic chemicals has been documented in the atmosphere of the Canadian prairies. The deposition of these chemicals as a mixture is of importance since little is known of the combined effects of these chemicals on aquatic organisms. This study was designed to evaluate the acute and chronic toxicity of a complex mixture of nine atmospherically transported pesticides to Ceriodaphnia dubia. The nine selected pesticides (bromoxynil, dicamba, 2,4-D, MCPA, triallate, trifluralin, pentachlorophenol, lindane, and 4,4'-DDT) were detected in appreciable quantities in dry atmospheric deposits. The concentration of each pesticide in the mixture was based on maximum measured daily dry deposition rates for central Canada, except for pentachlorophenol, which was estimated based on atmospheric concentrations. The 48-h LC50 estimate for C. dubia exposed to the pesticide mixture was 174.60 microg L(-1) (340 times the measured total dry deposition concentration). The estimated NOEC and LOEC for both survival and reproduction, as determined in the 7-d chronic toxicity test, were 51.3 (100 times) and 154 microg/L(-1) (300 times), respectively. A basic risk assessment, using the toxic unit approach, suggested that the toxicity of the pesticide mixture was mainly due to 4,4'-DDT. Overall, this atmospherically transported complex mixture of pesticides appears to pose a negligible toxicological risk to non-target aquatic invertebrates such as zooplankton.

Air Pollutants↗
PubMed1999

Chlorophenol and nitrophenol metabolism by Sphingomonas sp UG30.

Sphingomonas sp UG30 is a pentachlorophenol (PCP)-degrading bacterial strain capable of degrading several nitrophenolic compounds, including p-nitrophenol (PNP), 2,4-dinitrophenol (2,4-DNP), p-nitrocatechol and 4,6-dinitro-o-cresol (DNOC). The ability to degrade both chlorophenolic and nitrophenolic compounds is probably not restricted to UG30, but may also be possessed by other pentachlorophenol-degrading Sphingomonas spp. The interesting question arises as to whether there is any point of convergence between the initial pathways of PCP and nitrophenol degradation in these microorganisms. There is some experimental evidence that PCP-4-monooxygenase is involved in metabolism of both p-nitrophenol and 2,4-dinitrophenol. Further studies are needed to confirm this and to examine the role(s) of other PCP-degrading enzymes in nitrophenol metabolism by this microorganism. In this paper, we review some of the taxonomic, biochemical, physiological and ecological properties of Sphingomonas sp UG30 with respect to biodegradation of PCP and nitrophenolic compounds.

Journal Article↗
PubMed1995

Gas chromatographic-mass spectrometric determination of chlorophenols in the urine of sawmill workers with past use of chlorophenol-containing anti-stain agents.

The aim of this work was to establish whether workers at sawmills where chlorophenol-containing anti-stain agents had been previously used were still exposed to chlorophenols. A gas chromatographic-mass spectrometric (GC-MS) procedure for the determination of chlorophenols in urine was developed. Chlorophenols were determined from hydrolysed urine as acetylated derivatives and determined by GC-MS using selected ion monitoring (SIM). Isolation of the chlorophenols with toluene gave the best extraction efficiencies (65-119%). Stability tests at -20 degrees C showed no degradation of the chlorophenols studied during 6 months. The limit of quantification was 3.6 ng mg-1 creatinine for 2,4,6-trichlorophenol, 5.5 ng mg-1 for 2,3,4,6-tetrachlorophenol and 3.6 ng mg-1 for pentachlorophenol. Traces of 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol were found both in previously exposed workers and in non-exposed controls, the urinary concentrations ranging from 1.1 to 15.9 ng mg-1 creatinine. The concentrations of urinary chlorophenols in previously exposed workers were of the same magnitude as those found in non-exposed controls and in the general population. The results show that it is unlikely that sawmill workers would be currently occupationally exposed to chlorophenols or polychlorinated dibenzo-p-dioxins and dibenzofurans via a contaminated work environment.

Acetylation↗
PubMed2003

Ozonolysis of phenols in aqueous solution.

In the ozonolysis of phenol in aqueous solution at pH 3, 7 and 10 the following products were quantified: catechol, hydroquinone, 1,4-benzoquinone, cis,cis-muconic acid, H2O2, 2,4-dihydroxybiphenyl and 4,4-dihydroxybiphenyl. At pH 10, material balance (products vs. phenol consumption) is obtained. Singlet dioxygen, O2(1 delta g), and .OH are formed as short-lived intermediates. The precursor of the latter, O3.-, and a phenoxyl radical is suggested to arise from electron transfer from phenol/phenolate to ozone. Addition of .OH to phenol gives rise to dihydroxycyclohexadienyl radicals which add dioxygen and eliminate HO2. thereby forming catechol/hydroquinone. In competition and catalysed by H+ and OH-, the dihydroxycyclohexadienyl radical eliminates water yielding a phenoxyl radical. At pH 10, they readily oxidize catechol and hydroquinone. This reforms phenol (accounting for the low phenol consumption) and yields higher-oxidised products, eventually 1,4-benzoquinone. cis,cis-Muconic acid can be accounted for by the Criegee mechanism, while O2(1 delta g) is released on the way to (some of the) catechol and hydroquinone. Similar reactions proceed with hydroquinone (products: 1,4-benzoquinone, 2-hydroxy-1,4-benzoquinone and H2O2, with high yields of O2(1 delta g) and .OH) and with catechol (products: 2-hydroxy-1,4-benzoquinone, cis,cis-muconic acid, H2O2 with high yields of O2(1 delta g) and .OH). Material balance is not obtained for these two systems. Pentachlorophenolate, pentabromophenolate and 2,4,6-triiodophenolate ions give rise to halide ions, O2(1 delta g) (58%/48%/10%) and .OH (27%/2%/0%). It is suggested that together with O2(1 delta g) the corresponding ortho- and para-quinones plus a halide ion are formed. Further halide ion is released upon the hydrolysis of these and other products. For pentachlorophenolate the material balance with respect to the short-lived intermediates is 85%. With the bromo- and iodophenolates the O2(1 delta g) yields are substantially lowered, most likely due to release of triplet (ground state) dioxygen induced by the heavy atom effect.

Journal Article↗
PubMed2005

Pulsed amperometric detection with poly(dimethylsiloxane)-fabricated capillary electrophoresis microchips for the determination of EPA priority pollutants.

A miniaturized analytical system for separation and detection of three EPA priority phenolic pollutants, based on a poly(dimethylsiloxane)-fabricated capillary electrophoresis microchip and pulsed amperometric detection is described. The approach offers a rapid (less than 2 min), simultaneous measurement of three phenolic pollutants: phenol, 4,6-dinitro-o-cresol and pentachlorophenol. The highly stable response (RSD = 6.1%) observed for repetitive injections (n > 100) reflects the effectiveness of Au working electrode cleaned by pulsed amperometric detection. The effect of solution conditions, separation potential and detection waveform were optimized for both the separation and detection of phenols. Under the optimum conditions (5.0 mM phosphate buffer pH = 12.4, detection potential: 0.7 V, separation potential: 1200 V, injection time: 10 s) the baseline separation of the three selected compounds was achieved. Limits of detection of 2.2 microM (2.8 fmol), 0.9 microM (1.1 fmol), and 1.3 microM (1.6 fmol) were achieved for phenol, 4,6-dinitro-o-cresol and pentachlorophenol, respectively. A local city water sample and two over-the-counter sore-throat medicines were analyzed in order to demonstrate the capabilities of the proposed technique to face real applications.

Air Pollutants↗
PubMed2002

Inhibition of bovine phenol sulfotransferase (bSULT1A1) by CoA thioesters. Evidence for positive cooperativity and inhibition by interaction with both the nucleotide and phenol binding sites.

Previous work with the bovine phenol sulfotransferase (bSULT1A1, EC ) demonstrated inhibition by CoA that was competitive with respect to the sulfuryl donor substrate, 3'-phosphoadenosine-5'-phosphosulfate (PAPS) (Leach, M., Cameron, E., Fite, N., Stassinopoulos, J., Palmreuter, N., and Beckmann, J. D. (1999) Biochem. Biophys. Res. Commun. 261, 815-819). Here we report that long chain acyl-CoAs are more potent inhibitors of bSULT1A1 and also of human dopamine sulfotransferase (SULT1A3) when compared with unesterified CoA and short chain-length acyl-CoAs. A complex pattern of inhibition was revealed by systematic variation of palmitoyl-CoA, PAPS, and 7-hydroxycoumarin, the acceptor substrate. Convex plots of apparent K(m)/V(max) versus [palmitoyl-CoA] were adequately modeled using an ordered rapid equilibrium scheme with PAPS as the leading substrate and by accounting for the possible binding of two equivalents of inhibitor to the dimeric enzyme. Interestingly, the first K(i) of 2-3 microm was followed by a second K(i) of only 0.01-0.05 microm, suggesting that positive subunit cooperativity enhances binding of long chain acyl-CoAs to this sulfotransferase. Simultaneous interaction of palmitoyl-CoA with both the nucleotide and phenol binding sites is suggested by two experiments. First, the acyl-CoA displaced 7-hydroxycoumarin from the highly fluorescent bSULT1A1.PAP.7-HC complex in a cooperative manner. Second, palmitoyl-CoA prevented the quenching of bSULT1A1 fluorescence observed with pentachlorophenol. Finally, titrations of bSULT1A1-pentachlorophenol complex with palmitoyl-CoA caused the return of protein fluorescence, and the binding of palmitoyl-CoA was highly cooperative (Hill constant of 1.9). Overall, these results suggest a model of sulfotransferase inhibition in which the 3'-phosphoadenosine-5'-diphosphate moiety of CoA docks to the PAPS domain, and the acyl-pantetheine group docks to the hydrophobic phenol binding domain.

Animals↗
PubMed2002

Migration of surrogate contaminants in paper and paperboard into water through polyethylene coating layer.

The migration of five surrogate contaminants, anthracene, benzophenone, dimethyl phthalate, methyl stearate and pentachlorophenol, from paper and paperboard into water through a polyethylene (PE) coating layer was investigated. Virgin paper and paperboard coated with PE films of 0.012 and 0.030 mm thickness were spiked evenly with standard 1-ml solutions containing 5mg of each surrogate. The spiked papers were placed in contact with the PE coating layer at 10 and 24 degrees C for 21 days. The resulting surrogate migration through the PE layer into 100ml water was measured by an analytical method developed here that used gas chromatography equipped with a flame ionization detector. Non-polar surrogates of anthracene and methyl stearate did not show any significant migration. In the case of the thin layer coating of 0.012 mm, polar water-soluble contaminants of benzophenone, dimethyl phthalate and pentachlorophenol showed an equilibrated or maximized migration after 1 day, even at a refrigerated temperature of 10 degrees C. A thick PE coating of 0.030 mm thickness delayed the progress of contaminant migration, which was also slower at lower temperature. Our results indicate that polyethylene coatings should not be seen as a complete barrier against possible contaminants in paper packaging materials under chilled or ambient conditions. Several variables such as coating thickness, temperature and suspected contaminants need to be considered to control the possible contamination risk from recycled or printed paper.

Absorption↗
PubMed1976

Contributions to ecological chemistry CVII1. Fate of lindane-14C in lettuce, endives and soil under outdoor conditions.

In seven successive outdoor experiments, lindane-14C was applied to lettuce or endive leaves as an aqueous formulation (about 12 mg on 20 plants for each experiment). The growing periods varied between 21 and 37 days. After this time, between 4.5% and 13.9% of the applied radiocarbon was recovered from the plants. Conversion rates to soluble metabolites as well as to unextractable residues appeared to be dependent on weather conditions. During the summer months, the radiocarbon in plants consisted of 36% soluble metabolites and of 30% unextractable residues (average of 4 experiments); in autumn, the conversion rates were much lower. The following metabolites were identified in both plant species by gas chromatography/mass spectrometry: a polar group (a free trichlorophenol, 2,3,4,6-tetrachlorophenol, pentachlorophenol, conjugates of the latter two compounds, and unidentified water-soluble products) amounting to 35% of the radioactivity in plants cultivated in summer, and a nonpolar group (a dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3,5, and/or 1,2,4,5-tetrachlorobenzene, pentachlorobenzene, hexachlorobenzene, and gamma-pentachlorocyclohexene) amounting to 1% of the radioactivity in plants cultivated in summer. The 20 cm top-soil layer had about 14% of the total radioactivity applied to all plants. Six % of the radioactivity recovered from the soil was soluble metabolites and about 50% was not extractable. The soluble metabolites comprised a polar group (free and conjugated 2,3,4,6-tetrachlorophenol, pentachlorophenol, and unidentified water soluble products) amounting to 5% of the radioactivity in the soil as well as a nonpolar group (1,2,3-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,3,5 and/or 1,2,4,5-tetrachlorobenzene, pentachlorobenzene, hexachlorobenzene, and gamma-pentachlorocyclohexene) amounting to 1% of the radioactivity in the soil.

Biodegradation, Environmental↗