Bioconcentration, biomagnification and metabolism of 14C-terbutryn and 14C-benzo[a]pyrene in Gammarus fossarum and Asellus aquaticus

The contribution of bioconcentration and biomagnification of 14C-terbutryn and 14C-benzo[a]pyrene via food and water to the bioaccumulation in Gammarus fossarum and Asellus aquaticus was investigated in single species-tests. In this investigation the uptake of 14C-terbutryn and 14C-benzo[a]pyrene via food and water by G. fossarum (L.) and A. aquaticus (L.) was examined. Bioconcentration factors (BCFs) and biomagnification factors (BMFs) were determined. Calculated BCFs were clearly higher than BMFs, indicating that water is the primary route of uptake. The uptake of terbutryn and benzo[a]pyren via water in G. fossarum and A. aquaticus is faster than uptake via food. The elimination and metabolism of the two chemicals by G. fossarum and A. aquaticus were studied. Terbutryn was eliminated almost completely in both species. In general, the elimination of terbutryn from G. fossarum and A. aquaticus was fast with half-life of 5 h. The elimination of terbutryn by G. fossarum after biomagnification is slower than after bioconcentration. No difference was found in elimination of terbutryn by A. aquaticus after biomagnification and after bioconcentration. Metabolites of terbutryn in G. fossarum and A. aquaticus were analyzed by HPLC. After the bioconcentration experiment a higher percentage of metabolites was found in G. fossarum than in A. aquaticus. This was confirmed for the experiment with uptake via food. The spectrum of metabolites was similar in both species, with hydroxyterbutryn being the major metabolism product in water. 14C-B[a]P could nearly completely be eliminated by G. fossarum (rest of activity 2%) after uptake via water. 14C-B[a]P could not be eliminated by G. fossarum and A. aquaticus after uptake via food. The metabolite could not be identified.     

Impact of carbon nanomaterials on the behaviour of 14C-phenanthrene and 14C-benzo-[a] pyrene in soil

The impact of fullerene soot (FS), single-walled (SWCNTs) and multi-walled (MWCNTs) carbon nanotubes on the behaviour of two ¹⁴C-PAHs in sterile soil was investigated. Different concentrations of carbon nanomaterials (0, 0.05, 0.1 and 0.5%) were added to soil, and ¹⁴C-phenanthrene and ¹⁴C-benzo[a]pyrene extractability assessed over 80 d through dichloromethane (DCM) and hydroxypropyl-β-cyclodextrin (HPCD) shake extractions. Total ¹⁴C-PAH activity in soils was determined by combustion, and mineralisation of ¹⁴C-phenanthrene was monitored over 14 d, using a catabolically active pseudomonad inoculum. No significant loss of ¹⁴C-PAH-associated activity from CNM-amended soils was observed over the ‘aging’ period. CNMs had a significant impact on HPCD-extractability of ¹⁴C-PAHS; extractability decreased with increasing CNM concentration. Additionally, ¹⁴C-phenanthrene mineralisation was inhibited by the presence of CNMs at concentrations of ≥0.05%. Differences in overall extents of ¹⁴C-mineralisation were also apparent between CNM types. It is suggested the addition of CNMs to soil can reduce PAH extractability and bioaccessibility, with PAH sorption to CNMs influenced by CNM type and concentration.     

Impact of repeated application on the binding and persistence of [14C]-DDT and [14C]-HCH in a tropical soil

An Indian sandy loam soil was initially treated with 1 kg a.i. ha(-1) of either [(14)C]-p,p'-DDT or [(14)C]-gamma-HCH during winter. DDT concentration after 30 days declined to 75.3%, which included 2.1% soil-bound residues. After 150 days, DDT levels further decreased to 42.4% with a concomitant increase in bound residues amounting to 5.9%. Identical treatment with HCH caused the residue levels to be reduced to 67.4 and 23.6%, after 30 and 150 days, respectively. During this period, the soil-bound residues of HCH increased from 5.2 to 12.8%. Repeat application to pre-treated soils in summer and subsequent field exposure for 30 days reduced the concentration of DDT to 52.1% and that of HCH to 42.4% of the total concentration following the second treatment. In parallel control experiments, which received only a single treatment, DDT levels declined to 61.3%, while HCH slumped to 45.3%, indicating a slower dissipation rate than in the corresponding repeated treatments. In repeat experiments, the soil-bound residues of DDT and HCH showed only a 1.07 to 1.08-fold increase in 30 days, as compared to three to ten-times increase in the control experiments. The results amply demonstrate that pre-treatment of tropical soils with DDT or HCH enhances their rate of dissipation and significantly reduce the formation of their soil-bound residues.     

Bioavailability of atrazine, pyrene and benzo[a]pyrene in European river waters.

Thirteen river waters and one humic lake water were characterized. The effects of dissolved organic matter (DOM) on the bioavailability of atrazine, pyrene and benzo[a]pyrene (B[a]P) was evaluated. Binding of the chemicals by DOM was analyzed with the equilibrium dialysis technique. For each of the water samples, 24 h bioconcentration factors (BCFs) of the chemicals were measured in Daphnia magna. The relationship between DOM and other water characteristics (including conductivity, water hardness and pH), and bioavailability of the chemicals was studied by performing several statistical analyses, including multiple regression analyses, to determine how much of the variation of BCF values could be explained by the quantity and quality of DOM. The bioavailability of atrazine was not affected by DOM or any other water characteristics. Although equilibrium dialysis showed binding of pyrene to DOM, the bioavailability of pyrene was not significantly affected by DOM. The bioavailability of B[a]P was significantly affected by both the quality and quantity of DOM. Multiple regression analyses, using the quality (ABS270 and HbA%) and quantity of DOM as variables, explained up to 70% of the variation in BCF of B[a]P in the waters studied.     

Dissipation of available benzo[a]pyrene in aging soil co-contaminated with cadmium and pyrene

A microcosm experiment was conducted to investigate the dissipation of available benzo[a]pyrene (BaP) in soils co-contaminated with cadmium (Cd) and pyrene (PYR) during aging process. The available residue of BaP in soil was separated into desorbing and non-desorbing fractions. The desorbing fraction contributed more to the dissipation of available BaP than the non-desorbing fraction did. The concentration of bound-residue fraction of BaP was quite low across all treatments. Within the duration of this study (250 days), transformation of BaP from available fractions to bound-residue fraction was not observed. Microbial degradation was the dominant mechanism of the dissipation of available BaP in the soil. The dissipation of available BaP was significantly inhibited with the increment in Cd level in the soil. The addition of PYR (250 mg kg^?1) remarkably promoted the dissipation of available BaP without reducing Cd availability in the soil. The calculated half-life of available BaP in the soil prolonged with the increment in Cd level; however, the addition of PYR shortened the half-life of available BaP by 13.1, 12.7, and 32.8 % in 0.44, 2.56, and 22 mg Cd kg^?1 soils, respectively. These results demonstrated that the inhibiting effect of Cd and the promoting effect of PYR on the dissipation of available BaP were competitive. Therefore, this study shows that the bioremediation process of BaP can be more complicated in co-contaminated soils.     

Mutagenic nitrated benzo[a]pyrene derivatives in the reaction product of benzo[a]pyrene in NO2-air in the presence of O3 or under photoirradiation

In order to clarify the contribution of nitrated products to the direct-mutagenic activity of products of the reactions of benzo[a]pyrene in NO2-air under various conditions, heterogeneous reactions of BaP deposited on filter in the air containing 10 ppm of NO2 have been conducted in dark or under photoirradiation. The reaction products have been analyzed by gas chromatography and mutagenicity of the products fractionated by preparative HPLC was assayed for Salmonella typhimurium strains TA98 and YG1024 in the absence of S9 mix. 3,6-dinitrobenzo[a]pyrene and 1,3-dinitrobenzo[a]pyrene, which are strong direct-acting mutagens, largely contributed to the total direct-acting mutagenicity of the dark reaction products in NO2-air. On the other hand, both the dark reaction in the presence of O3 and the photoreaction in NO2-air resulted in the formation of much smaller amounts of nitrobenzo[a]pyrenes than that observed in the dark reaction in the absence of O3. These results show that the contribution of other direct-acting mutagens to the total direct-acting mutagenicity of the products in these reactions should be considered. Benzo[a]pyrene lactones were identified in a highly mutagenic fraction of the products of the dark reaction in the presence of O3 and photoreaction and a nitrobenzo[a]pyrene lactone was also identified in a highly mutagenic fraction of the dark reaction products in the presence of O3. Nitrated oxygenated benzo[a]pyrene derivatives such as nitrobenzo[a]pyrene lactone were considered to largely contribute to direct-acting mutagenicity of the products of the dark reaction in the presence of O3 and photoreaction.     

Comparison of microbial pyrene and benzo[a]pyrene mineralization in liquid medium, soil slurry, and soil

The microbial degradation of 14C-pyrene and 14C-benzo[a]pyrene by a bacterial mixed culture was studied within a mixture of the PAHs phenanthrene, anthracene, pyrene, fluoranthene, and benzo[a]pyrene as sole carbon source in the different culture systems: (i) liquid medium, (ii) soil slurry (surface and grinding influence), and (iii) soil. The fate of these two labeled compounds was followed in these systems with an emphasis on mineralization to carbon dioxide, extractability, and adsorption to humic materials and formation of unextractable residual. Mineralization showed the most obvious differences: soil slurries achieved the best results both concerning the extent of mineralization and the time required. The highest extent of pyrene mineralization (54% within 21 days) was observed in soil slurries; in liquid media, pyrene mineralization was slower, but reached approximately the same extent (54% in 150 days); in soils, mineralization reached only 36% of added pyrene after 160 days. Benzo[a]pyrene was mineralized in a mixture of PAHs in soil slurries to an extent of 34% within 70 days, whereas mineralization in liquid medium and soil occurred in the range of 5% (70 days). Mineralization of benzo[a]pyrene in sand slurries was lower compared to soil slurries (19% in sand slurries vs. 32% in soil slurries within 50 days).     

Metabolic fate of [14C]-2,4-dichlorophenol in macrophytes

The metabolic fate of 2,4-dichlorophenol (DCP) was investigated in six macrophytes representing different life forms. Salvinia natans and Lemna minor were chosen as surface-floating plants, Glyceria maxima and Mentha aquatica as emergent species and Myriophyllum spicatum and Hippuris vulgaris as submerged aquatic plants. After uptake of a [U-phenyl-14C]-DCP solution followed by a 48 h water chase, whole plants (L. minor, S. natans) or excised shoots were harvested and aqueous extracts were analysed by high performance liquid chromatography (HPLC). Metabolites were then isolated, submitted to enzymatic or chemical hydrolyses and characterised by electrospray ionisation-mass spectrometric analyses. Whereas DCP monoglucosides or more complex monoglucoside esters, either malonyl or acetyl, were found in most species, an unusual glucosyl-pentose conjugate was identified as the DCP major metabolite in L. minor and G. maxima. Our results showed for the first time the ability of five macrophytes to uptake and metabolise DCP and the characterisation of their metabolic pathways of DCP biotransformation.     

Synthesis of [14C]biphenyl and of some chlorinated [14C]biphenyls containing 4-chloro-, 2,4-dichloro- and 2,3,6-trichlorophenyl nuclei from the corresponding labelled anilines

The preparation of ¹⁴C-labelled biphenyl, 2,5-dichlorobiphenyl, 2,4′,5-trichlorobiphenyl, 2,2′,4,5′-tetrachlorobiphenyl, 2′,3,4,4′,5-pentachlorobiphenyl, 2,2′,3,4,4′-pentachlorobiphenyl, 2,3,3′,4′,6-pentachlorobiphenyl and 2,2′,3,3′,6-pentachlorobiphenyl is described [¹⁴C]Aniline hydrogen sulfate used as a starting material was acetylated, chlorinated and deacetylated followed by coupling to benzene or an appropriate chlorobenzene to give the biphenyls labelled in the phenyl nuclei having chlorine atoms at the 4-, 2,4- or 2,3,6-positions, respectively. The structures of the labelled compounds were established by comparison with authentic samples among which 2′,3,4,4′,5- and 2,2′,3,4,4′-pentachlorobiphenyl were not earlier described.A simple method for the preparation of 2,3,6-trichloroacetanilide, unlabelled and labelled, was worked out. 2,6-Dichloroacetanilide in concentrated hydrochloric acid gave the $\text{meta}$ substituted product when treated with chlorine.An improved thin layer chromatographic technique utilizing plates impregnated with certain tetraalkylammonium salts was used for separation of some of the labelled compounds prepared.     

Bioaccumulation of cyclopenta[cd]pyrene and benzo[ghi]fluoranthene by mussels transplanted in a coastal lagoon

The bioaccumulation of two isomeric non-alternant non-priority polycyclic aromatic hydrocarbons (PAHs), namely cyclopenta[cd]pyrene and benzo[ghi]fluoranthene, was investigated in caged mussels (Mytilus galloprovincialis) exposed for 30 days in three sites of a coastal lagoon (Pialassa Baiona, Ravenna, Italy) contaminated by pyrogenic PAHs. The concentration of cyclopenta[cd]pyrene and benzo[ghi]fluoranthene increased from undetectable levels in reference mussels withdrawn from the Adriatic sea to 10-30 ng g(-1) dry weight in transplanted mussels. Other contaminants bioaccumulated by caged mussels included pyrene, fluoranthene and mercury. Whilst the isomer concentration ratio pyrene/fluoranthene in biota was comparable to that observed in sediments, the cyclopenta[cd]pyrene/benzo[ghi]fluoranthene ratio was much lower in mussels than in sediments. The lower sediment biota accumulation factor of cyclopenta[cd]pyrene with respect to that of benzo[ghi]fluoranthene was tentatively attributed to the greater biological activity of the former compound, which contains a reactive olefinic bond in the cyclopenta fused ring moiety. Given the higher mutagenic activity of cyclopenta[cd]pyrene with respect to other priority PAHs, its bioaccumulation from contaminated sediments may rise considerably the overall toxicity of PAH residues in exposed biota.     

Fluoranthene, but not benzo[a]pyrene, interacts with hypoxia resulting in pericardial effusion and lordosis in developing zebrafish

Previous research has documented several PAHs that interact synergistically, causing severe teratogenicity in developing fish embryos. The coexposure of CYP1A inhibitors (e.g. FL or ANF) with AHR agonists (e.g. BaP or BNF) results in a synergistic increase in toxicity. As with chemical CYP1A inhibitors, it has also been shown that CYP1A morpholinos exacerbate BNF-induced embryotoxicity. We hypothesized that a hypoxia-induced reduction in CYP1A activity in BNF or BaP-exposed zebrafish embryos would similarly enhance pericardial effusion and other developmental abnormalities. BaP, BNF, ANF, and FL exposures, both individually and as BaP+FL or BNF+ANF combinations, were performed under hypoxia and normoxia. CYP1A activity in the BaP+hypoxia and BNF+hypoxia embryos was reduced by approximately 60% relative to normoxia embryos. Although CYP1A activity was significantly reduced, we did not observe any increase in pericardial effusion in either group. An unexpected yet particularly interesting result of these experiments was the observed interaction of both FL and ANF with hypoxia. Relatively high, yet environmentally relevant concentrations of FL (100-500 microg L(-1)) interact with moderate hypoxia (7.3% DO) through an unknown mechanism, resulting in pericardial effusion and severe lordosis. Additionally, ANF exposures (100 microg L(-1)) which are not normally teratogenic caused dramatic pericardial effusion, but not lordosis, when embryos were coexposed to hypoxia. These results suggest that reduced CYP1A activity may not exclusively underlie observed developmental toxicity, and that hypoxia may exacerbate the developmental toxicity of some PAH mixtures.     

Bioavailability to rats of bound [14C] pirimiphos-methyl in stored wheat.

Stored wheat treated with radiolabelled pirimiphos-methyl (0-2-diethyl-amino-6-methyl-pyrimidin-4-yl 0,0-dimethyl phosphorothioate) formed bound (nonextractable) 14C residues. Supercritical fluid extraction, gas chromatography and mass spectrometric techniques were used to identify and quantitate the 14C bound residues in wheat grains. The amount of bound 14C residues present after 28 weeks of storage was about 9.9% of the applied radioactivity. Pirimiphos-methyl accounted for 80% of the bound residue. Grain-bound residues were fed to rats for 5 days. After a total period of 8 days a substantially large percentage of the administered bound 14C residues (72.9%) was eliminated in urine while feces contained only 17.9%. Bound pirimiphos-methyl in wheat grain was metabolized in rats by processes involving hydrolysis, N-dealkylation and 0-demethylation. The results indicate that wheat-bound residues of pirimiphos-methyl are highly bioavailable to the rat and may possess a toxicological potential as manifested by a significant reduction in body weight gain.     

Tissue distribution of 2,2',4,4'-tetrabromo[14C]diphenyl ether ([14C]-PBDE 47) in pike (Esox lucius) after dietary exposure--a time series study using whole body autoradiography

In the present study, the tissue distribution of [14C]-labelled 2,2',4,4'-tetrabrominated diphenyl ether (PBDE 47) and its possible metabolites was investigated after dietary exposure in pike (Esox lucius) using whole-body autoradiography. The study is a time series with pike examined 9, 18, 36 and 65 days after exposure. PBDE 47 was efficiently absorbed from the food (>90%) and radioactivity remained in the body in considerable amounts even after the longest period examined. The results indicate that PBDE 47 is not rapidly metabolised to hydrophilic, but possible to hydrophobic metabolites and that PBDE 47 and possible hydrophobic metabolites are accumulated in the lipid rich tissues of the pike. Melanin binding of PBDE 47 and possible metabolite(s) is suggested. The levels of PBDE 47 and/or metabolite(s) declines with time in most tissues except for the most lipid rich, where no decline in radioactivity is observed even after the longest period studied. Signs of irreversible incorporation of PBDE 47-derived radioactivity were detected but considered as too uncertain to conclude that covalent binding of PBDE 47-metabolites to macromolecules occurs.     

Enhanced degradation of benzo[a]pyrene by Mycobacterium sp. in conjunction with green alga

Previous work in this laboratory has confirmed that the bacteria Mycobacterium sp. strain RJGII.135 and Sphingomonas yanoikuyae strain B1 and the green alga Selanastrum capricornutum strain UTEX 1648 degrade benzo[a]pyrene (BaP) to various BaP intermediates. S. capricornutum was first grown with BaP for 4 days. The organic extract of this media was then introduced into separate cultures of strain RJGII.135 and strain B1; separate cultures were grown with BaP for comparison. Cultures grown with BaP and those grown with the algal/BaP extract showed similar mineralization patterns. The quantity of total metabolites formed was greater in bacterial cultures grown with the algal/BaP extract than those grown with BaP alone. For strain RJGII.135, only 27% of the original BaP remained in cultures grown with the algal/BaP extract; 59% remained in cultures grown with BaP. For strain B1, only 6% of the original BaP remained in cultures grown with the algal/BaP extract; 38% remained in cultures grown with BaP. These results indicate that strategies utilizing organisms together may be necessary in being able to degrade large, recalcitrant polycyclic aromatic hydrocarbons (PAHs) such as BaP.     

Effects of anthracene, pyrene and benzo[a]pyrene spiking and sewage sludge compost amendment on soil ecotoxicity during a bioremediation process

The fate of spiked anthracene, pyrene and benzo[a]pyrene in soil with or without sewage sludge compost was assessed during a 6-month bioremediation process simulating landfarming. Bioassays and physico-chemical analyses were employed to monitor toxicity change in soil samples and elutriates through ten sampling campaigns. Pearson product-moment correlation coefficient was determined to measure the strength of relationship between bioassays and physico-chemical analyses. The PAH dissipation in soil was enhanced after the first water addition, and the remaining amounts at the end of the experiment were positively correlated to the number of benzene rings and the presence of sewage sludge compost. Toxicity of soil elutriates to Daphnia magna was evident at early stages, originating exclusively from sewage sludge compost amendment. The lettuce root elongation was continuously inhibited by elutriates for all the treatments including control soil, probably due to high salinity or to unaddressed leachable phytotoxic compounds that were present in the experimental soil. The newly developed direct solid-phase chronic toxicity test using ostracod (Heterocypris incongruens) succeeded in evaluating the soil-bound PAH toxicity, as PAHs could not be detected in elutriates.     

Formation, characterization and release of non-extractable residues of [14C] -labeled organic xenobiotics in soils

The amount of non-extractable residues (NER) of organic xenobiotics in the soil can considerably exceed the amount of extractable residues which are accessible to normal residue analysis. The NER therefore present a burden to the soil, the toxicological and ecotoxicological potential of which is largely unknown. For the characterization of bound residues and their binding type, special solubilization methods such as supercritical fluid extraction are applied and experiments with radiolabeled model polymers are performed. Mineralization experiments with [¹⁴C] labeled xenobiotics in natural soil show that a total degradation is still also possible in the environment when in a bound form. Ecotoxicological effects of non-extractable residues may be recorded when their concentration is high, when the parent compound exhibits a high ecotoxicity and the applied detection method is sufficiently sensitive.     

Residues of lindane and its metabolites in eggs, chicks, and body tissues of hen pheasants after ingestion of lindane-14C via treated wheat seed or gelatin capsules.

Studies were carried out to investigate possible contamination of pheasants with residues of lindane used as seed dressings for the control of wireworms in cereal crops. One group of laying hen pheasants was fed 20 mg of lindane-14C in gelatin capsules while another group was fed wheat seed treated with 100 ppm of lindane-14C for 15 days. Residues in eggs were monitored for about 70 days. Residues in chicks hatched from the eggs were also measured. Concentrations of residues in muscle, liver, brain, and fatty tissues were determined at various times. 14C-labeled residues in eggs increased sharply in the capsule treated group and reached an average maximum of about 19 ppm in 8 days. This level decreased to less than 0.5 ppm in about 50 days. Residues in eggs from the pheasants fed treated seed increased gradually to an average maximum of 17 ppm 22 days after commencement of the feeding program. This level decreased to less than 0.5 ppm 50 days later. Residues in hatched chicks were significantly lower than those in the eggs. Highest concentrations of residues were found in fatty tissues which decreased to non-detectable level in 6 months. Several chlorobenzene metabolites were identified in egg yolk and chick tissues. Chlorophenolic metabolites were indicated only in chicks.     

Degradation of [14C]isofenphos in soil in the laboratory under different soil pH's, temperatures, and moistures

The effects of three soil pH's, three soil temperatures, and three soil moistures on [14C]isofenphos degradation were investigated. All three factors interacted strongly and significantly affected the persistence of isofenphos as well as the formation of the degradation products (p less than 1%). Isofenphos degradation was greatest at the higher temperatures 35 degrees C greater than 25 degrees C greater than 15 degrees C (except under alkaline pH's), medium moisture 25% greater than 30% greater than 15%, and in both alkaline (pH = 8) and acidic soils (pH = 6) compared with neutral soil (pH = 7). Isofenphos oxon formation was greatest at higher temperatures 35 degrees C compared with 25 degrees C and 15 degrees C, in acidic soil greater than neutral soil greater than alkaline soil, and under high moisture (30%) compared with the 15% and 22.5% moistures. The formation of soil-bound residues was greatest at higher temperatures 35 degrees C greater than 25 degrees C greater than 15 degrees C, higher moisture 30% compared with 15% and 22.5%, and in alkaline soil compared with neutral and acidic soils.