ORCID Profile
0000-0002-0524-2215
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Publisher: Springer Science and Business Media LLC
Date: 03-1986
DOI: 10.1038/320160A0
Publisher: American Chemical Society (ACS)
Date: 08-10-2008
DOI: 10.1021/ES801601X
Abstract: Previously, comprehensive two-dimensional gas chromatography-time of flight-mass-spectrometry (GCxGC-ToF-MS) revealed that the unresolved complex mixtures (UCMs) of contaminant hydrocarbons accumulated by health-affected mussels Mytilus edulis (up to 125 microg g dry weight(-1)) collected from around U.K. coasts, included many isomeric branched alkyl benzenes (BABs). A commercial mixture of BABs (C12-C14) was toxic to mussels in laboratorytests (tissue effective concentration EC(20)10.5 microg g dry tissue(-1)). Branched alkyl indanes (BINs) and branched alkyl tetralins (BATs) were also tentatively identified in the wild mussels, but no commercial sources of BINs or BATs were available for compound confirmation or toxicity testing. In the present study, we synthesized 14 isomeric BINs and BATs, investigated their chromatographic and mass spectral properties and measured their toxicity to mussels (Mytilus edulis). Comparison of the results of GCxGC-ToF-MS analysis of the synthesized compounds with those of complex mixtures of BINs and BATs in wild mussels confirmed the previous tentative identifications. Toxicity assays showed that in 72 h exposures, each of the synthetic BINs and BATs and a mixture of all were toxic to mussels at concentrations comparable to the BABs investigated previously (EC(20)13 microg g dry tissue(-1)). A further 5 day recovery period in clean water resulted in incomplete depuration of the accumulated body burden of BINs and BATs by the mussels. We suggest that monitoring of hydrocarbon contaminants in mussels should include an assessment of the concentrations of aromatic UCMs and ideally identification and measurement of the concentrations of BABs, BINs, and BATs and other toxic UCM components in order that the effects of these toxicants are not overlooked.
Publisher: Elsevier BV
Date: 1989
Publisher: Elsevier BV
Date: 06-2005
Publisher: Elsevier BV
Date: 12-1981
Publisher: American Chemical Society (ACS)
Date: 12-11-2008
DOI: 10.1021/ES801922P
Abstract: The rapid expansion of the oil sands industry has seen a concomitant expansion of the production of associated waste containing toxic naphthenic acids (NAs). Bioremediation of such waste is thus an important goal, but the mechanisms of biodegradation are still poorly understood, despite recent advances. Many oil sands NAs are resistant to biodegradation, and alkyl side chain branching has been invoked as an explanation. To investigate this hypothesis we examined the biotransformation by a sedimentary bacterial community of novel, synthetic, surrogate NAs (butylcyclohexylbutanoic acids (BCHBAs)) with variously branched butyl side chains (n- through t-) and unbranched alkanoate groups, plus one (4-(4'-isobutylcyclohexyl)pentanoic acid (iso-BCHPA)), with both branched butyl and branched alkanoate chains. Sediment microbial populations were inoculated into media containing the in idual surrogate NAs, and gas chromatography-mass spectrometry (GC-MS) was used to determine the extent of biotransformation. Biotransformation decreased as NA side chain branching increased. For ex le, over 97% of the n-BCHBA with the nonbranched alkyl side chain was transformed in 30 days compared to the tert-BCHBA with the most highly branched side chain where only 2.5% was transformed. Both the iso-BCHBA and sec-BCHBA had intermediate transformation rates with about 77% and 47% transformed respectively after 30 days. The metabolites were identified as butylcyclohexylethanoic acids in each case, indicating beta-oxidation of the alkanoate substituents. The iso-BCHPA with both chains branched was resistant to degradation. The results are thus consistent with earlier hypotheses for the resistance of oil sands NAs. Identification of bacteria capable of oxidizing such branched alkyl chains-or of attacking the cyclic rings of NAs, may be important if bioremediation of oil sands NAs is to be achieved.
Publisher: Elsevier BV
Date: 11-1999
Publisher: Elsevier BV
Date: 1989
Publisher: Elsevier BV
Date: 03-2000
DOI: 10.1016/S0031-9422(99)00571-3
Abstract: The partial configurations of C25 isoprenoid alkenes isolated from the diatom Haslea ostrearia Gaillon (Simonsen) have been established. A combination of NMR spectroscopy studies of the alkenes with chiral shift reagents in conjunction with soluble silver beta-diketonate complexes and enantioselective gas chromatography of oxidation products of the alkenes was used. Unexpected differences in highly branched isoprenoid isomer configurations were observed between different laboratory cultures of the alga.
Publisher: Elsevier BV
Date: 1989
Publisher: Elsevier BV
Date: 1988
Publisher: Elsevier BV
Date: 07-2004
Publisher: Elsevier BV
Date: 04-2007
Publisher: Elsevier BV
Date: 07-1993
Publisher: The Royal Society
Date: 15-07-1993
Abstract: It is perhaps a truism that sedimentary organic geochemical processes can best be quantified if the concentrations of the major organic chemicals are known. While numerous authors have reported the concentrations of one or other compound classes, relatively few studies have accounted for all of the organic carbon in a well-resolved depth sequence of Recent sediments. In the present study, we report a mass balance for organic carbon in 1 cm sections of Recent sediment (0-10 cm) from offshore Peru by measuring the major, operationally defined classes of biochemicals: proteins, carbohydrates and lipids. However, in deeper sediments in the same core (200 cm), the proportion of organic carbon that can be accounted for by present analytical methods is only about 60%, and recalculation of published data shows that this decreases to only a few percent at 100 m depth. We discuss briefly, methods which have proved useful for characterization of the uncharacterized fraction which some workers have termed humin or ‘proto-kerogen’. The smooth and rapid decreases in the proportions of ‘protein’ and ‘carbohydrate ’ carbon and ‘ bound ’ lipids in this core are attributed to diagenetic alteration rather than to variations in input, confirming many previous results. The overall proportions of free lipids, in contrast, did not decrease systematically in the shallowest sediments (0-25 cm). This is not reflected in most previous studies of in idual lipids, many of which decrease rapidly with depth in these sediments. We suggest that interactions within the lipids may account for this apparent discrepancy.
Publisher: Elsevier BV
Date: 12-1997
Publisher: Wiley
Date: 02-2007
Abstract: Examination by high temperature GC (HTGC) of the methyl esters of the so-called 'ARN' naphthenic acids from crude oils of North Sea UK, Norwegian Sea and West African oilfields revealed the distributions of resolved 4-8 ring C80 tetra acids and trace amounts of other acids. Whilst all three oils contained apparently the same major acids, the proportions of each differed, possibly reflecting the growth temperatures of the archaebacteria from which the acids are assumed to have originated. The structures of the 4, 5, 7 and 8 ring acids are tentatively assigned by comparison with the known 6 ring acid and related natural products and an HPLC method for the isolation of the in idual acids is described. ESI-MS of in idual acids isolated by preparative HPLC established the elution order of the 4-8 ring acids on the HPLC and HTGC systems and revealed the presence of previously unreported acids tentatively identified as C81 and C82 7 and 8 ring analogues.
Publisher: Elsevier BV
Date: 1989
Publisher: Elsevier BV
Date: 07-1997
Publisher: Elsevier BV
Date: 1984
Publisher: Springer Science and Business Media LLC
Date: 12-1985
DOI: 10.1038/318651A0
Publisher: Wiley
Date: 1995
Publisher: American Chemical Society (ACS)
Date: 24-06-2011
DOI: 10.1021/ES201234A
Abstract: Alkylnaphthalenes (AN) are relatively water-soluble hydrocarbons which, following spillages of crude oils, have been widely reported in contaminated marine organisms such as mussels. In the present report we show, by tandem-gas chromatography-time-of-flight-mass spectrometry (GC × GC-ToF-MS), that the range of AN in contaminated wild mussels from the UK extends beyond the previously GC resolved isomers to those with at least seven substituent carbon atoms. Since surprisingly little information on AN toxicity to such marine organisms has been reported we synthesized two C(8) AN and measured the toxicity of C(2-8) AN to mussels (clearance rate assay). C(2-3) AN were appreciably toxic (concentration for 50% clearance rate inhibition, 48 h IC(50) 1.4-2.6 μmol g(-1) dry weight tissue), but several C(4), (6) and C(8) AN, including branched isomers expected to be resistant to biodegradation and more accumulative, were relatively nontoxic (48 h IC(50) > 10 μmol g(-1)) and longer term exposure (8d) failed to elicit a greater toxic response. The accumulation profiles of AN in laboratory mussels exposed to oil were similar to those of the wild mussels. Moreover, laboratory oil-exposed mussels depurated toxic C(2-3) AN within 5 days in clean water and clearance rates recovered. The latter might imply that, in contrast with branched alkyl benzenes tested previously, AN are of less toxic concern, but such a straightforward conclusion cannot necessarily be drawn a synthetic branched C(8) AN persisted following depuration and was as toxic to mussels as a C(3) AN (IC(50) 1.3 μmol g(-1)). This indicates that the structures of AN are also important.
Publisher: American Chemical Society (ACS)
Date: 07-12-2007
DOI: 10.1021/ES0615829
Publisher: The Royal Society
Date: 25-07-1985
Abstract: Recently it has been shown that the measured extent of reactions in sedimentary biological marker compounds during catagenesis (for ex le, steroid aromatization, sterane isomerization) can assist in providing information about the extent of maturation of sedimentary organic matter before and during oil generation and also the thermal history of sediments. In the present study, aromatization of a C 27 C-ring aromatic steroid and isomerization at the chiral centres of an isoprenoid alkane, 6( R ),10( S )-pristane, have been brought about under laboratory conditions, elemental sulphur being used as the source of radicals. Precise rate laws have been determined and rate coefficients measured at different temperatures. The pre-exponential factors and activation energies were found to be 6.7 x 10 12 s -1 and 145 kJ mol -1 for the aromatization, and 2.1 x 10 7 s -1 and 120 kJ mol -1 for the configurational isomerization of pristane. These values reflect the relative behaviour of the two types of reactions in sediments, the aromatization being the more temperature-dependent reaction.
Publisher: Elsevier BV
Date: 1985
Publisher: Elsevier BV
Date: 07-1988
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for C. Anthony Lewis.