Leo C. Osuji

Chemical reclamation of crude-oil-inundated soils from Niger Delta, Nigeria

Crude-oil-inundated soils were collected from the Agbada oil field in the Niger Delta region of Nigeria 2 months after the recorded incidence of oil spillage. The soils were taken on the second day of reconnaissance from three replicate quadrats, at surface (0–15 cm) and subsurface (15–30 cm) depths, using the grid sampling technique. The total extractable hydrocarbon content (THC) of the polluted soils ranged from 1.24 × 102 to 3.86 × 104 mg/kg at surface and subsurface depths (no overlap in standard errors at a 95% confidence level). Greenhouse trials for possible reclamation were later carried out using 10–100 g of (NH4)2SO4, KH2PO4 and KCl (NPK) fertilizer as nutrient supplements. Nitrogen as NO3-N and potassium were optimally enhanced at 2% (w/w) and 3% (w/w) of the NPK supplementation, respectively. Phosphorus, which was inherently more enhanced in the soils than the other nutrients, maintained the same level of impact after treatment with 20 g of NPK fertilizer. Total organic carbon (%TOC), total organic matter (%TOM), pH, and percentage moisture content all provided evidence of enhanced mineralization in the fertilizer-treated soils. If reclamation of the crude-oil-inundated soils is construed as the return to normal levels of metabolic activities of the soils, then the application of the inorganic fertilizers at such prescribed levels would duly accelerate the remediation process. However, this would be limited to levels of pollution empirically defined by such THC values obtained in this study.

HYDROCARBON CONTAMINATION OF A TYPICAL MANGROVE FLOOR IN NIGER DELTA, NIGERIA

The impact of petroleum hydrocarbons on the floor of a mangrove system located on one of the intertidal lands behind the barrier islands of Niger Delta basin of southern Nigeria was evaluated following the Obiafu-14 oil spillage. The area covered by the oil spill was delimited by reconnaissance and soils were sampled by grid method from the bottom and middle slopes of oil-affected and unaffected (control) sites. Soil samples were later brought to the laboratory where total hydrocarbon content was determined by extraction and spectrophotometric techniques. A lower pH range of 4.28–4.36 in the oil impacted soils meant that the site was more acidic; a higher moisture content of 33.34% and lower electrical conductivity (EC) of 31.75μS/cm in the affected area presupposed oxygen deprivation and lower salt content respectively. On the strength of the baseline data on the study area and evidence from the uncontaminated, geographically similar control site, it can be said that the Obiafu-14 oil spillage had severely contaminated the affected mangrove floor. This is corroborated by a total extractable hydrocarbon content of 6.32×103 ± 344 mg/kg (no overlap in Standard Error at 95% Confidence Limit), and the abysmal degradation of the mangrove system at the site. Although soils of the mangrove floor under consideration may well be of limited cultivation value on account of the people’s dual occupation in fishing and farming, the presence of such levels of petroleum hydrocarbons at the study site might hamper agricultural productivity.

Evaluation and Decontamination of Crude Oil-Polluted Soils Using Centrosema pubescen Benth and Amendment-Support Options

Growth performance and phytoremediation of soil of the Niger Delta Region of Nigeria artificially-contaminated with crude oil (up to 100 mL/2 kgsoil) using centrosema pubescen Benth was investigated for 12 weeks. The soil samples in which the plants were established were either un-amended, or amended with NPK, or UREA or chicken manure. The extents of removal of PAHs and BTEX were measured as well as the rates of growth of the plants. Gas Chromatographic analysis confirmed the degradation of carcinogenic hydrocarbons like BTEXs and PAHs with this technique. At the highest dose of crude, the contaminant concentrations were 43mg/kg PAHs, 10mg/kg BTEX, and 5,613mg/kg O&G. The greatest percent removal of BTEX was observed at the highest contaminant dose, and with the manure amendment. Similar trends were observed with PAHs and although they were less marked, the trends with PAHs may have been more highly statistically significant. There was no measurable plant uptake of contaminants. Inhibition of plant growth (measured as leaf area, shoot length and production of dry weight) was proportional to the dose of crude oil, but the manure amendment was very effective at reducing the growth inhibition. Interestingly, manure amendment reduced the phytotoxicity significantly in this study.

Upstream petroleum degradation of mangroves and intertidal shores: the Niger Delta experience.

This article was inspired by a field reconnaissance survey of outcrops along the Nembe‐Brass axis of the petroliferous Niger Delta. It reviews various tradeoffs of the impact of upstream petroleum (seismic and production) operations on the mangrove ecosystems in that region, the largest in Sub‐Saharan Africa. Mangroves and intertidal shores are considered critical to the economic well‐being of this region owing to the peoples dual occupation in fishing and farming. The mangrove ecosystem provides a nutrient medium, which serves as a nursery and spawning ground for many fish species and other biota. Oil and gas activities might destroy these spawn areas, causing reduction in resource output and community pressure. Devegetation of the mangrove forest as a result of seismic delineation leaves the fragile soil exposed, unprotected, and susceptible to erosion. Again, loss of vegetation might discourage the natural role of plants in air purification (CO2 utilization and O2 production). The release of nutrients (organic N2, NH3, and NO

Hydrocarbon Speciation by Fingerprinting Technique and Diagnostic Vanadium/Nickel Ratio of Mgbede-20 Oil-Impacted Site in the Niger Delta Basin of Nigeria

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Impact of four-dimensional seismic and production activities on the mangrove systems of the Niger Delta, Nigeria

) and polyaromatic hydrocarbons (PAHs) to the environment, with the attendant increase in microbial load, increases biochemical O2 demand (BOD) and depletes dissolved O2 (DO) in H2O to a level that is beyond the tolerance limit of organisms. This anoxic situation leads to asphyxiation and subsequent fish kill in affected areas. In order of increasing vulnerability, the mangroves and intertidal shores of the Niger Delta fall under categories 8 to 10 on the environmental sensitivity index (ESI) scale, which predisposes the areas to serious long‐term effects and clean‐up complexity. Thus, there is need to monitor mangrove systems and shoreline changes in the areas of considerable seismic and production activities, especially in the coastal Niger Delta, where pipeline corrosion due to salt intrusion into the swampy environment and ‘unsighted fingers’ of sabotage have increased the prevalence of oil spills.

Multivariate analysis of source and maturity biomarker indices of crude oils from SW Niger Delta

This article describes the speciation and recognition of the hydrocarbon distribution pattern and the diagnostic ratios of source-specific pristane and phytane for the characterization of the chemical composition and source identification of spilled oil at Mgbede-20 in the Niger Delta Basin of southern Nigeria. Gas chromatography fingerprinting and data interpretation of analyses of oil residues from the site indicated that the released oil was a partially degraded paraffin-base crude oil with fairly well resolved peaks in the n−C11 to n−C23 range. The chromatograms also contained the acyclic isoprenoids pristane and phytane, at mean concentrations of 8,100 ± 1,700 mg/kg and 24,000 ± 7,300 mg/kg, respectively (without overlap in standard errors at 95% confidence level). The loss of the light end n-alkanes of carbon numbers lower than n−C11 indicated that the spilled oil was only slightly weathered after the spill incident and that the chemical composition of the aliphatic components had not undergone significant alteration, suggesting that the on-site spilled oil was relatively fresh. A mean pristane-to-phytane (Pr/Ph) ratio of 0.39 was obtained for replicate spill samples; these Pr/Ph ratios were suggestive of an anoxic-derived source crude oil, with some likely non-waxy, marine-derived organic matter content. The V-to-N; ratios and the distribution of polycyclic aromatic hydrocarbons may serve as a corrective profile for future characterization of the Mgbede-20 oil.

The Effect of the Adulteration of Premium Motor Spirit (PMS) on Automotive Engines

Reconnaissance survey and laboratory appraisal of the mangrove system in seven communities in the Niger Delta (Nigeria) endangered by seismic and production operations revealed several alterations of soil, sediment, and vegetation. Hydrocarbon content in the range of 0.3–1.1 mg/100 g was extracted within the proximities of spill sources and seismic lines. The prospect area covered by our investigation was characterized by a mixed mangrove forest dominated by Rhizophora racemosa. It was observed that the construction of the seismic lines was responsible for the vegetal disorientation recurrent in the area. The grass, Paspalum vaginatum, and the saltwater fern, Acrostichum aureum, were found at the fringe of most dredge spoils. The characteristic tidal inundation which increases mobility of the substrate, salinity fluctuation, and anoxia may also have contributed, at least in part, to the observed despoliation of some of these species found within the vicinities of the seismic lines and hydrocarbon percolation. Extensive revegetation program is recommended to ensure an effective restoration process of this ecologically fragile zone.

Quantal response of Paleomonetes africanus in locally formulated drilling mud lubricants

Saturated biomarker source and maturity parameters obtained from Gas chromatography-mass spectrometry were analyzed using multivariate statistical methods to maximize diagnostic information on the hopanes and sterane spectrum. This statistical method provided the identification of structural relationships (similarities and differences) between various fingerprint descriptors for the crude oil samples. The results emphasized the separation of the oil samples in regards to their locations into two genetic families. This separation pattern is more evident when principal component analysis was applied to biomarker data compared with the standard biomarker cross-plots. Such compositional differences are commonly attributed to unique source rock paleodepositional environments. The plotted source and maturity diagnostic parameter in a dendrogram separated the oils into two families both having terrestrial input. The group that have higher terrestrial input contain more oleananes, and have the highest Pr/Ph ratio. They are generated from source rocks with a high abundance of terrestrial organic matter. The second groups of oils have mixes of terrestrial and marine organic matter with lesser amount of oleananes.

Comparison of the Phase Changes of Binary Mixtures n-Alkanes of Lower Carbon Numbers

Ten samples of premium motor spirit were collected at different dispensing points and analyzed to determine the extent at which the adulteration of this petroleum product affects automotive engines. Results of the analyses shows, research octane number values from 60.10 to 93.30, specific gravity from 0.7523 to 07885, Reid vapor pressure from 0.28 to 0.60 kgf/cm2, while atmospheric distillation ranges from 189 to 251°C. The result of this research reveals that most of the products are highly adulterated and this is not desirable for spark-ignited engines, as it may lead to the problem of detonation, insufficient supply of engine power, slow rate of deflagration experienced by most consumers, and consistent knock of spark-ignited engines.