Two strains of bacteria capable of carrying out the 0-methylation of phenolic compounds, one from the gram-positive genus Rhodococcus and one from the gram-negative genus Acinetobacter, were used to examine the 0-methylation of phenols carrying fluoro-, chloro-, and bromo-substituents. Zero-order rates of 0methylation were calculated from data for the chloroand bromophenols; there was no simple relationship between the rates of reaction and the structure of the substrates, and significant differences were observed in the responses of the two test organisms. For the gram-negative strain, the pattern of substitution was as important as the number of substituents. Hexachlorophene was resistant to 0-methylation by both strains, and tetrabromobisphenol-A was 0-methylated only by the gram-positive strain. It is suggested that in the natural environment, bacterial 0-methylation of phenols carrying electron-attracting substituents might be a significant alternative to biodegradation.

Two strains of bacteria, provisionally assigned to the genus Arthrobacter, were shown to metabolize mono-, di-, tri-, and tetrachloroguaiacols and pentachlorophenol to the corresponding 0-methyl compounds. Hydroxylated intermediates were formed only transiently, except for the synthesis by one strain of 3,4,5trichlorosyringol from 3,4,5-trichloroguaiacol. Two isomeric trichloroveratroles and tetrachloroveratrole were formed by three of the strains from a highmolecular-weight chlorinated lignin isolated from kraft pulp mill bleach plant. The concentrations of methylated metabolites varied widely and did not appear to be correlated with degradation. The possible environmental consequences resulting from synthesis of these highly lipophilic substances are discussed briefly.

Soil quality standards are based on partitioning and toxicity data for laboratory-spiked reference soils, instead of real world, historically contaminated soils, which would be more representative. Here 21 diverse historically contaminated soils from Sweden, Belgium, and France were obtained, and the soil-porewater partitioning along with the bioaccumulation in exposed worms (Enchytraeus crypticus) of native polycyclic aromatic compounds (PACs) were quantified. The native PACs investigated were polycyclic aromatic hydrocarbons (PAHs) and, for the first time to be included in such a study, oxygenated-PAHs (oxy-PAHs) and nitrogen containing heterocyclic PACs (N-PACs). The passive sampler polyoxymethylene (POM) was used to measure the equilibrium freely dissolved porewater concentration, Cpw, of all PACs. The obtained organic carbon normalized partitioning coefficients, KTOC, show that sorption of these native PACs is much stronger than observed in laboratory-spiked soils (typically by factors 10 to 100), which has been reported previously for PAHs but here for the first time for oxy-PAHs and N-PACs. A recently developed KTOC model for historically contaminated sediments predicted the 597 unique, native KTOC values in this study within a factor 30 for 100% of the data and a factor 3 for 58% of the data, without calibration. This model assumes that TOC in pyrogenic-impacted areas sorbs similarly to coal tar, rather than octanol as typically assumed. Black carbon (BC) inclusive partitioning models exhibited substantially poorer performance. Regarding bioaccumulation, Cpw combined with liposome-water partition coefficients corresponded better with measured worm lipid concentrations, Clipid (within a factor 10 for 85% of all PACs and soils), than Cpw combined with octanol-water partition coefficients (within a factor 10 for 76% of all PACs and soils). E. crypticus mortality and reproducibility were also quantified. No enhanced mortality was observed in the 21 historically contaminated soils despite expectations from PAH spiked reference soils. Worm reproducibility weakly correlated to Clipid of PACs, though the contributing influence of metal concentrations and soil texture could not be taken into account. The good agreement of POM-derived Cpw with independent soil and lipid partitioning models further supports that soil risk assessments would improve by accounting for bioavailability. Strategies for including bioavailability in soil risk assessment are presented.

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We have demonstrated that strains of bacteria belonging to the genera Pseudomonas and Acinetobacter possessed the ability to transform, by O-methylation, components of spent bleachery effluent such as 4,5,6-trichloroguaiacol and high molecular weight chlorinated lignin. O-Methylation could be enhanced by the presence of a cosubstrate such as succinate or 4-hydroxybenzoate. We have used zebra fish (Brachydanio rerio) to examine bioconcentration potential, toxicity to embryos and larvae, and the sensitivity of the offspring of exposed adults. Bioconcentration factors (total wet weight) on a logarithmic scale were 3.5 and 4.4 for 3,4,5-trichloroveratrole and tetrachloroveratrole, respectively. The potential for bioconcentration of the other neutral metabolites was inferred from estimated values of the octanol–water partition coefficients. 3,4,5-Trichloroveratrole, tetrachloroveratrole, pentachloroanisole, and 1,2,3-trichloro-4,5,6-trimethoxybenzene had threshold toxic concentrations to zebra fish embryos and larvae of 450, 100, 2.8, and 450 μg∙L−1, respectively, and all of them were capable of inducing, at somewhat lower concentrations, various deformations including curvature of the larvae and distortion of the notochord. Experiments on the effect of preexposure of adults to tetrachloroveratrole at a concentration of 16 μg∙L−1 showed that the offspring were adversely affected, e.g. in a decreased viability of the embryos, lowered median survival time for larvae, and greater sensitivity to tetrachloroveratrole. Both 3,4,5-trichloroveratrole (5–150 μg∙kg liver fat−1) and tetrachloroveratrole (40–400 μg∙kg liver fat−1) were detected in fish from localities subjected to discharge of bleachery effluent, and were absent in fish from uncontaminated localities. Identification of these compounds was based on gas chromatographic, and for tetrachloroveratrole, mass spectrometric, comparison with authentic compounds. We conclude that not only compounds present in bleachery effluent, but those that may be produced in the environment by bacterial O-methylation, have potentially hazardous biological activities. These results shed fresh light on a hitherto neglected aspect of environmental hazard assessment, and we suggest that data for a given compound must be supplemented with that for metabolites that could be produced in the environment.