首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 875 毫秒
1.
In the presence of the cancerogenic benzo(a)pyrene (4 × 10?7 mole/1) the rate the of biochemical oxidation of phenols and a mixture of oil-shale alkylresorcinols (5 × 10?5 mole/1) on activated sludges adapted to these phenols is reduced up to 30%. The oxidation of benzo(a)pyrene occurs at a high rate, the rate constant on both sludges being 6.8 × 108 mole/1 · sec and exceeds the index of the processes of its selfpurification by two orders. The high efficiency of the biooxidation of benzo(a)pyrene is retained at a repeated use of the same biomass, thus no additional regeneration being needed. Some products of the, biooxidation of benzo(a)pyrene, such as 1,6- and 3,6-quinone, derivatives of chrysene and naphthalene, are identified.  相似文献   

2.
In batch experiments with 0.5 nM benzo(a)pyrene in artificial sea water there are investigated the distribution and degradation of benzopyrene in the presence of various plants: Cladophora glomerata, Enteromorpha intestinalis, Fucus vesiculosus and Chara aspera (in each case 10 … 20 g/l dry weight). The conversion of benzopyrene in the presence of the plants is considerably promoted compared with the pure autoxidation, except in the presence of Fucus. Obviously, there prevails initially the accumulation of benzopyrene in the biomass. Whereas for Fucus even after 10 d still 89% of benzopyrene can be detected in the biomass, in the other species a degradation of benzopyrene in the biomass takes place, the respective oxidation products as diols, quinones and phenols being detected in the biomass in proportionately higher concentrations. With the exception of Fucus, the degradation of benzopyrene comes up to 40 … 60% within a period of 5 … 6d with the other species tested.  相似文献   

3.
The kinetics of oxidation of carcinogenic benzo(a)pyrene (0.1 nM solution in phosphate buffer) catalyzed by enzyme protein of soil and water plants (potato tubers and alga Nitella sp.) has been studied. The benzo(a)pyrene oxidation rate is determined by the phenoloxidase activity of the enzyme protein from both sources to an equal degree and expressed by the Michaelis-Menten equation. The values for kcat and apparent Km were (0.97 ± 0.14) Ms?1 and 33 ± 6 μM, respectively. The presence of other compounds (including protein substances) in acetone preparations of potato tubers considerably suppresses its catalytic activity in relation to benzo(a)pyrene. Consequently, in the polluted biosphere some water plants, such as alga Nitella sp., and potato tuber can transform carcinogenic benzo(a)pyrene (BP). As oxidation products, all three BP-quinones, i.e. 1,6-, 3,6-and 6,12-diones, were identified.  相似文献   

4.
A study was conducted using an estuarine sediment maintained under controlled pH and redox potentials to determine the effect of these parameters on the degradation of benzo(a)pyrene. Degradation was strongly influenced by sediment pH and redox potential. Highest degradation rates occurred in sediment maintained at pH 8.0 and the lowest at pH 5.0. At all pH values degradation of benzo(a)pyrene increased with increasing redox potential. Up to a hundredfold difference in degradation rates could be attributed to changes in sediment pH and redox potential.  相似文献   

5.
Marine mussels accumulate the carcinogen benzo(a)pyrene from contaminated environments. Baseline studies in California indicate that levels of the carcinogen in mussels are at or near zero, except in areas of human activity. This finding runs counter to previous suggestions that benzo(a)pyrene is widely distributed in marine organisms.  相似文献   

6.
Biomarkers are generally applied to detect pollution in environmental monitoring. Such biological responses should accurately reflect the stress over time in a quantitative manner. As such, the initial and maximum responses induced by stress, as well as adaptation and recovery of these biomarkers, need to be fully understood or else erroneous false-negative or false-positive may be arrived. However, most of the biomarker studies only provided information on initially induced responses under different concentrations of toxicants, while biological adaptation and recovery were poorly known. In this study, the time required for induction, adaptation and recovery of lysosomal integrity in green-lipped mussel Perna viridis upon exposure to benzo[a]pyrene was investigated over a period of 62 days. Maximum induction occurred on day 6 when lysosomal integrity was significantly reduced by 51%, and no further change or adaptation was detected thereafter. When mussels were depurated in clean seawater after 18 days of exposure to benzo[a]pyrene, a gradual recovery was observed, with lysosomal integrity returning to its background level and showing a complete recovery after 20 days of depuration. Lysosomal integrity was significantly correlated with the body burden concentrations of benzo[a]pyrene and condition index of the mussels. The relatively fast induction (6 days) and recovery (20 days) without apparent adaptation suggested that lysosomal integrity in P. viridis can serve as a good biomarker in biomonitoring, as its response is not likely to generate both false-negative and false-positive results.  相似文献   

7.
Polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCs) are generally present in the marine environment in complex mixtures. The ecotoxicological nature of contaminant interactions, however, is poorly understood, with most scientific observations derived from single contaminant exposure experiments. The objective of this experiment was to examine dose-response relationships between antioxidant parameters and body contaminant levels in mussels exposed to different exposure regimes under laboratory conditions. Accordingly, the green-lipped mussel, Perna viridis, was challenged with a mixture of PAHs (anthracene, fluoranthene, pyrene, benzo[a]pyrene) and OC pesticides (α-HCH, aldrin, dieldrin, p,p′-DDT) over a 4 week period. Contaminants were delivered under four different dosing regimes, with all treatments receiving the same total contaminant load by the end of the exposure period. Antioxidant biomarkers were measured after 1, 2, 3 and 4 weeks, including glutathione (GSH), gluathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and lipid peroxidase (LPO). GST and CAT were induced in hepatic tissues in most of the exposure regimes, with the majority of significant induction occurring in a constant exposure regime and a two-step alternate exposure regime. Significant differences among exposure regimes were detected in the body burden of contaminants after 28 days. Hepatic CAT and GSH are proposed as potentially useful biomarkers as they showed good correlation with target contaminants and were not readily affected by different dosing patterns.  相似文献   

8.
Eight marine-derived fungi that were previously selected for their abilities to decolorize RBBR dye were subjected to pyrene and benzo[a]pyrene degradation. The fungus Aspergillus sclerotiorum CBMAI 849 showed the best performance with regard to pyrene (99.7%) and benzo[a]pyrene (76.6%) depletion after 8 and 16 days, respectively. Substantial amounts of benzo[a]pyrene (>50.0%) depletion were also achieved by Mucor racemosus CBMAI 847. Therefore, these two fungal strains were subjected to metabolism evaluation using the HPLC-DAD-MS technique. The results showed that A. sclerotiorum CBMAI 849 and M. racemosus CBMAI 847 were able to metabolize pyrene to the corresponding pyrenylsulfate and were able to metabolize benzo[a]pyrene to benzo[a]pyrenylsulfate, suggesting that the mechanism of hydroxylation is mediated by a cytochrome P-450 monooxygenase, followed by conjugation with sulfate ions. Because these fungi were adapted to the marine environment, the strains that were used in the present study are considered to be attractive targets for the bioremediation of saline environments, such as ocean and marine sediments that are contaminated by PAHs.  相似文献   

9.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in the environment and are derived from both man-made and natural resources. The present study is focused on the degradation of PAHs by a halotolerant bacterial strain under saline conditions. The bacterial strain VA1 was isolated from a PAH-degrading consortium that was enriched from marine water samples that were collected from different sites at Chennai, India. In the present study, a clearing zone formed on PAH-amended mineral salt agar media confirmed the utilization of PAH by the bacterial strain VA1. The results show that the strain VA1 was able to degrade anthracene (88%), phenanthrene (98%), naphthalene (90%), fluorene (97%), pyrene (84%), benzo(k)fluoranthene (57%) and benzo(e)pyrene (50%) at a 30 g/L NaCl concentration. The present study reveals that the VA1 strain was able to degrade PAHs in petroleum wastewater under saline conditions. The promising PAH-degrading halotolerant bacterial strain, VA1, was identified as Ochrobactrum sp. using biochemical and molecular techniques.  相似文献   

10.
The fixed wavelength fluoresce (FF) method was used to estimate the levels of fluorescent aromatic compounds (FACs) in the bile of fourteen fish species of commercial and/or ecological interest. Sampling was carried out in the NW Mediterranean at depths ranging from 50 to 1000 m during four seasonal cruises. During the summer sampling period, some species were also collected from another site (Vilanova fishing grounds) for comparison. Baseline levels of the polycyclic aromatic hydrocarbons (PAHs) naphthalene, phenanthrene, pyrene and benzo[a]pyrene were measured. Some seasonality was observed, with reduced FF levels in summer and no differences among sites, consistent with sediment PAH levels. We discuss our results in relation to fish phylogeny, season, depth, diet, trophic level and swimming capacity. Overall FF levels indicated differences among species; the suprabenthic feeders from shallow and deep communities, and Mullus barbatus in particular, displayed elevated FF values and are potential candidates for additional monitoring studies.  相似文献   

11.
The influence of dioxybenzenes and their quinones on Dunaliella salina, Nitella sp. and Elodea canadensis was investigated. It was established that the higher the rate of polyphenol oxidation by the aqueous plants, the higher the toxicity of the compound being studied is and the larger the reduction of the SH-group content due to the incubation of plants in these polyphenol solutions is. Formation of o- and p-benzoquinones by the aquatic plants in the course of dioxybenzene oxidation was proved. Treatment of plants with quinone solutions led to a larger SH-group concentration drop than with phenols. Oxidation products of pyrocatechol, caffeic and chlorogenic acids caused the greatest decrease of the SH-group content directly at the moment of their preparation, i. e., when the o-quinone concentration was at its maximum. The conclusion is drawn that a higher degree of toxicity to the aquatic plants of pyrocatechol and hydroquinone, in comparison with other phenols, is due to their ability to oxidize phenols to quinones. It is suggested that one of the possible biochemical mechanisms for demonstrating the toxic action of the phenol oxidation products is the blocking of SH-groups.  相似文献   

12.
Woo S  Kim S  Yum S  Yim UH  Lee TK 《Marine pollution bulletin》2006,52(12):1768-1775
To investigate the genotoxic effect of marine sediments on aquatic organism, sediment samples were collected from 13 sites along the coast of Gwangyang Bay (Korea). Concentrations of polycyclic aromatic hydrocarbons (PAHs) in sediments were determined and the relationship between exposure of flounder blood cells to sediment extracts and DNA single-strand breakage in the blood cells was examined using the comet assay. Levels of DNA damage were proportionally increased by exposure concentration and the highest sediment-associated DNA damage was observed at the station showing the highest PAHs contamination. DNA damage in blood cells exposed to five types of PAHs (benzo[a]pyrene, fluoranthene, anthracene, pyrene and phenanthrene) and in flounder (Paralichthys olivaceus) exposed to benzo[a]pyrene (BaP) for 0, 2 and 4 days were assessed by measuring comet tail length. The tail lengths of five PAHs-exposed groups at 50 and 100 ppb were significantly different from the non-exposed group, and the genotoxic effect of BaP correlated with both concentration and duration of exposure. Throughout the study, significant differences in DNA breakage were recorded between cells exposed to sediment extracts or PAHs and non-exposed control. This study demonstrated the comet assay as a successful tool in monitoring contamination of marine sediments and assessing genotoxicity of PAHs in marine organisms, either in vitro or in vivo.  相似文献   

13.
Macrobrachium lamarrei is exposed to 0.008, 0.017 and 0.021 mg/1 aldrin (0.4, 0.8 and 1.0 of the LC50,96h) for 24… 96 h and after exposure the activities of the acid, alkaline and glucose-6-phosphatases are determined. With concentration and time of exposure the acid phosphatase shows an increasing activity up to 170 % compared with the control, which is interpreted as a part of prenecrotic changes in the cells. With concentration and time of exposure the alkaline phosphatase shows a decreasing activity down to 20 % of the control, which is indicative of considerable disturbances of the total metabolism. The glucose-6-phosphatase shows an increasing activity with the aldrin concentration up to 150 % during 72 h; then the activity drops to 60… 80 %. The initial rise in the glucose concentration of blood caused by that is the clear consequence of a stress reaction and the change of metabolism resulting from it.  相似文献   

14.
The acute toxicity of copper and copper plus complexing agents to common guppy Lebistes reticulatus was studied for 96 h by a static bioassay technique. The addition of complexing agents viz. disodium salt of EDTA, citric acid, sodium thiosulphate and glycine in Cu2+ solutions caused a great decrease in the per-cent mortality as compared to that of Cu2+ test solutions alone. 10 mg/l of complexing agent was added in each copper concentration in all the test series. The 96 h LC50 values and 95% confidence limits in mg/l of Cu2+ plus were 1.23 (0.95…1.65) for Cu2+ alone; 4.30 (4.04 … 4.55) for Cu2+ plus EDTA; 1.94 (1.69 … 2.18) for Cu2+ plus citric acid; 3.44 (2.96 … 3.74) for Cu2+ sodium thiosulphate and 2.29 (2.22 … 3.02) for Cu2+ plus glycine.  相似文献   

15.
The outer layers of layflat, low density polyethylene plastic tubing (the principal component of semi-permeable membrane devices, SPMDs) were biofouled at a clean site in Hong Kong coastal waters for periods of 1–4 weeks. Following pre-fouling, triolein was added to the SPMDs and, along with control (unfouled) devices, they were exposed to a range of organochlorine pesticides (-HCH, aldrin, p,p′-DDT) and PAHs (anthracene, fluoranthene and benzo(a)pyrene) under laboratory conditions. Results showed that the uptake of contaminants by SPMDs was severely reduced by as much as 50% under fouling conditions in comparison to unfouled controls. The ultimate utility of SPMDs as passive monitors is thus reduced, although alternative measures, such as the use of permeability reference compounds may compensate, and allow for realistic evaluations of dissolved environmental concentrations in aquatic environments. However, due to the complexities involved in such procedures––especially as they need to be conducted on a case-by-case basis––the utility of SPMDs appears to be limited for estimates of bioavailability unless necessary calibrations are undertaken within each environment that the sampler is used.  相似文献   

16.
The concentration of phenols and quinones which stopped the protoplasmic movement in the Nitella cells after 15 min was determined. The quinones (β-naphthoquinone, α-naphthoquinone, p-benzoquinone, o-toluquinone, o-bromanil) stopped the protoplasmic movement in the concentration of (1 3) 10?4 M, phenols (m-cresol, p-cresol, hydroquinone, guaiacol, phenol, gallic acid, pyrogallic acid, resorcinol) in the concentration of (0.2 5) 10?2 M, except catechol – 2 10?3 M. Very high toxicity of catechol and in the prolonged experiments (3 hours) also of hydroquinone is connected with the action of quinonoid productions of its oxidation. This suggestion is confirmed by the experiments:
  • – by adding the phenol solutions to Nitella shoots (catechol, hydroquinone, resorcinol) we observed the greatest increase of oxygen absorption in case of catechol (86%), less in case of hydroquinone (38%), and for resorcinol oxygen absorption practically remained on the control level;
  • – the action of catechol, hydroquinone and p-benzoquinone did not take place in the presence of glutathione and cysteine (but not cystine and oxidated glutathione);
  • – diethyldithiocarbamate as an inhibitor of o-diphenoloxidase reduced the ability of catechol solutions to stop the protoplasmic movement;
  • – the low concentrations of benzoquinones were able to stop the protoplasmic movement;
  • – for stopping the protoplasmic movement under the prolonged time of incubation from 15 min to 3 hours there was necessary a lower concentration of solutions of hydroquinone and catechol in comparison with resorcinol.
  相似文献   

17.
Concentrations of polycyclic aromatic hydrocarbons were determined in species of commercial fish and lobsters following an oil-spill just off the protected Madagascan coastline. Samples were collected along the coastline within and outside the affected area. Summed PAH concentrations ranged from 1.9 μg kg−1 to 63 μg kg−1 wet weight, but with no higher molecular weight PAHs (>202 Da) being detected. All concentrations of benzo[a]pyrene, benz[a]anthracene and dibenz[a,h]anthracene were <0.1 μg kg−1 wet weight, well within the EU and UK set limits for the protection of human health. Additionally, samples were calculated as the benzo[a]pyrene toxic equivalency quotient (TEQ) and found to be well below the level of concern in relation to health of human consumers. Evaluation of the biota PAH data indicated the origin of PAH was predominantly petrogenic with >80% arising from oil sources. Profile studies indicate a low-level multisource petrogenic contamination probably representing a pre-spill background for the area.  相似文献   

18.
《Marine pollution bulletin》2009,58(6-12):503-514
Polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCs) are generally present in the marine environment in complex mixtures. The ecotoxicological nature of contaminant interactions, however, is poorly understood, with most scientific observations derived from single contaminant exposure experiments. The objective of this experiment was to examine dose-response relationships between antioxidant parameters and body contaminant levels in mussels exposed to different exposure regimes under laboratory conditions. Accordingly, the green-lipped mussel, Perna viridis, was challenged with a mixture of PAHs (anthracene, fluoranthene, pyrene, benzo[a]pyrene) and OC pesticides (α-HCH, aldrin, dieldrin, p,p′-DDT) over a 4 week period. Contaminants were delivered under four different dosing regimes, with all treatments receiving the same total contaminant load by the end of the exposure period. Antioxidant biomarkers were measured after 1, 2, 3 and 4 weeks, including glutathione (GSH), gluathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and lipid peroxidase (LPO). GST and CAT were induced in hepatic tissues in most of the exposure regimes, with the majority of significant induction occurring in a constant exposure regime and a two-step alternate exposure regime. Significant differences among exposure regimes were detected in the body burden of contaminants after 28 days. Hepatic CAT and GSH are proposed as potentially useful biomarkers as they showed good correlation with target contaminants and were not readily affected by different dosing patterns.  相似文献   

19.
Static bioassay tests were carried out on Channa punctatus Bloch in the laboratory after renewal of concentrations every 24 h. The LC50 values and 95 per cent confidence limits were 45.21 (39.62 … 51.11) ppm at 12 h and 29.8 (27.49 … 31.95) ppm of Zn at 96 h of exposure. The actual dissolution values of zinc were also determined in test solutions using an atomic absorption spectrophotometer. Behavioural changes were the higher rate of opercular movements, surfacing, loss of equilibrium and haemorrhage near mouth and caudal fin. The LT50 values indicate that survival was increased with decreasing Zn concentration. The histopathological changes observed due to Zn toxicity in the gills have been discussed in relation to fish mortality.  相似文献   

20.
We studied the relative competitive abilities of littoral cladocerans M.triserialis and A. rectangula using green algal food at two levels (0.5 · 106 and 2 · 106 cells mL−1 of Chlorella) under five different inoculation ratios. Both the cladoceran species were influenced by food availability and mutual competitive pressure. Macrothrix could withstand competition better under conditions of lower food availability while Alona grew better, despite competition, when more Chlorella was available. Population growth rates (r) ranged from 0.022…0.070 for Alona and from 0.024…0.075 for Macrothrix. There was a significant impact of the inoculation ratio on the maximal population density reached by either test species. Food concentration had a significant influence on the peak population density reached only for Alona rectangula. Data on the body sizes of M. triserialis and A. rectangula showed that there was a higher somatic growth with increasing food availability and decreased competitive pressure in both the test species. In Macrothrix, food concentration and the competition from Alona through different initial inoculation densities had a significant impact on the body size. At the lower food concentration, the body size was significantly smaller when the inoculation density was lowest (highest competitive pressure). The body size of Alona, on the other hand, was not affected by the competition but was significantly higher under conditions of greater food availability. These results have been discussed in light of different theories of competition.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号