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The Niger Delta Basin is one of the most prolific hydrocarbon provinces in the world, yet the origin of the vast amounts of oil and gas found in the numerous sub-basins across the delta remains contested. A total of 180 oil samples from more than 40 oil fields in the Niger Delta were analyzed by gas chromatography (GC), GC-mass spectrometry (GC-MS) and selected samples by GC-tandem mass spectrometry (GC-MSMS). The interpreted thermal maturity and source depositional environments of these hydrocarbons show significant variation depending on the components analyzed, and allow no clear correlation to a single source rock but rather imply extensive mixed contributions. Diamondoid hydrocarbon parameters were used for the first time on these Paleogene–Neogene reservoired oils to investigate source, thermal maturity and mixing effects and to perform cross-correlations of these oils. The diamondoid abundances and distributions support the hypothesis of co-sourcing of oil from a thermally cracked, sub-delta, Type II marine source, which was then mixed with oils of relatively lower maturities in the Paleogene–Neogene reservoirs. Future geochemical interpretations should treat the Niger Delta oils as potential mixtures of oils of variable maturities from different sources, often with the most important source biomarkers depleted because of the extent of thermal cracking.

N and P are the key limiting nutrients considered most important for the stimulation of crude oil degradation but other trace nutrients may also be important. Experimental soil microcosms were setup to investigate crude oil degradation in the context of Ni amendments. Amended Nickel as NiO, NiCl2, or, a porphyrin complex either inhibited, had no effect, or, enhanced aerobic hydrocarbon degradation in an oil-contaminated soil. Biodegradation was significantly (95% confidence) enhanced (70%) with low levels of Ni-Porph (12 mg/kg) relative to an oil-only control; whereas, NiO (200 and 350 mg/kg) significantly inhibited (36 and 87%) biodegradation consistent with oxide particle induced reactive oxygen stress. Microbial community compositions were also significantly affected by Ni. In 16S rRNA sequence libraries, the enriched hydrocarbon degrading genus, Rhodococcus, was partially replaced by a Nocardia sp. in the presence of low levels of NiO (12 and 50 mg/kg). In contrast, the highest relative and absolute Rhodococcus abundances were coincident with the maximal rates of oil degradation observed in the Ni-Porph-amended soils. Growth dependent constitutive requirements for Ni-dependent urease or perhaps Ni-dependent superoxide dismutase enzymes (found in Rhodococcus genomes) provided a mechanistic explanation for stimulation. These results suggest biostimulation technologies, in addition to N and P, should also consider trace nutrients such as Ni tacitly considered adequately supplied and available in a typical soil.

Pristane (2,6,10,14-tetramethylpentadecane), frequently the most abundant biomarker hydrocarbon in crude oils and rock extracts, was thought originally to be derived directly from phytol or, later, from thermal degradation of tocopherols. We present new evidence supporting the hypothesis that pristane, under certain conditions, may result from the catagenic decomposition of methyltrimethyltridecylchromans (MTTCs) derived during diagenesis from condensation reactions between chlorophyll and alkylphenols. We show that phytol can condense, under mild conditions, with phenolic systems (in free or polymeric form) to produce free or bound structures that generate pristenes on flash pyrolysis. We suggest straightforward tests of this hypothesis.

General procedures are outlined for the asymmetric syntheses of lignans of the dibenzylbutyrolactone, dibenzylbutanediol, aryltetralin and dibenzocyclooctadiene series, from tandem addition products derived from 4-menthyloxybutenolide.

Bioremediation and activated carbon (AC) amendment were compared as remediation strategies for sediment from the River Tyne containing 16.4 +/- 7.3 microg/g polycyclic aromatic hydrocarbons (PAHs) and approximately 5% coal particles by total dry sediment weight. Unamended, nutrient amended (biostimulated) and nutrient and Pseudomonas putida amended (bioaugmented) sediment microcosms failed to show a significant decrease in total sediment PAH concentrations over a one month period. Polyethylene passive (PE) samplers were embedded for 21 days in these sediment microcosms in order to measure the available portion of PAHs and accumulated 4.70 +/- 0.25, 12.43 +/- 1.78, and 23.49 +/- 2.73 microg PAHs/g PE from the unamended, biostimulated, and bioaugmented microcosms, respectively. Higher PAH uptake by PE samplers in biostimulated and bioaugmented microcosms coincided with slower degradation of spiked phenanthrene in sediment-free filtrate from these microcosms compared to filtrate from the unamended microcosms. Microbial community analysis revealed changes in the bacterial community directly following the addition of nutrients, but the added P. putida community failed to establish itself. Addition of 2% by dry sediment weight activated carbon reduced PAH uptake by PE samplers to 0.28 +/- 0.01 microg PAHs/g PE, a greater than 90% reduction compared to the unamended microcosms.

Addition of sulphur stabilised carbanions to a chiral non-racemic butenolide followed by reaction with an aromatic aldehyde affords a short synthesis of homochiral dibenzylbutyrolactone derivatives. Desulphurisation of the first formed adducts proceeds in almost quantitative yield to afford the parent lignan.

Enolate anions obtained by conjugate addition to (–)-5-(1-menthyloxy)furan-2(5H)-one are quenched with benzyl bromides or iodides to yield homochiral dibenzylbutyrolactones. Desulfurisation followed by lithium aluminium hydride reduction affords homochiral 2,3-dibenzylbutane-1,4-diols, including (–)dimethylsecoisolariciresinol and (–)-dihydroclusin. Desulfurisation followed by reduction with NaBH4/KOH gives the homochiral 2,3-dibenzylbutyrolactones (–)-dimethylmatairesinol, (–)kusunokinin and (–)-yatein, which undergo stereoselective oxidative coupling with DDQ in trifluoroacetic acid to give homochiral tetrahydrodibenzocyclooctene lignans belonging to the isostegane series.

Addition of sulfur-stabilised carbanions to (–)-5-(1-menthyloxy)furan-2(5H)-one followed by reaction with an aromatic aldehyde affords a short synthesis of enantiomerically pure dibenzylbutyrolactone derivatives. Desulfurisation with NaBH4/NiCl2 proceeds in almost quantitative yield, and reduction with NaBH4/KOH gives the parent dibenzylbutyroactones including (–)-6-epi-podorhizol. These undergo cyclisation with acid to give homochiral aryltetralins including (–)-deoxyisopodophyllotoxin in high yield.