Eucharia Oluchi Nwaichi

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.

Enhanced Phytoremediation of Crude Oil-Polluted Soil by Four Plant Species: Effect of Inorganic and Organic Bioaugumentation

A field experiment investigating the removal and/or uptake of Polycyclic Aromatic Hydrocarbons (PAHs) and specific metals (As, Cd, Cr) from a crude oil polluted agricultural soil was performed during the 2013 wet season using four plant species: Fimbristylis littoralis, Hevea brasilensis (Rubber plants), Cymbopogom citratus (Lemon grass), and Vigna subterranea (Bambara nuts). Soil functional diversity and soil-enzyme interactions were also investigated. The diagnostic ratios and the correlation analysis identified mixed petrogenic and pyrogenic sources as the main contributors of PAHs at the study site. A total of 16 PAHs were identified, 6 of which were carcinogenic. Up to 42.4 mg kg−1 total PAHs was recorded prior to the experiments. At 90 d, up to 92% total PAH reduction and 96% As removal were achieved using F. littoralis, the best performing species. The organic soil amendment (poultry dung) rendered most of the studied contaminants unavailable for uptake. However, the organic amendment accounted for over 70% of the increased dehydrogenase, phosphatase, and proteolytic enzymes activities in the study. Overall, the combined use of soil amendments and phytoremediation significantly improved the microbial community activity, thus promoting the restoration of the ecosystem.

Characterization and safety evaluation of the impact of hydrocarbon contaminants on ecological receptors.

Hydrocarbon-contaminant removal efficiency of Bambara groundnuts and biomagnification was investigated. The crude oil contaminated soil samples in which the plants were established were either un-amended, or amended with NPK, or Urea, or Poultry manure. Amendments improved phytoextraction rates as follows: Urea – 63.37%, NPK – 65.99%, Poultry – manure – 70.04%, for PAH; Urea – 78.80%, NPK – 79.80%, Poultry manure – 87.90%, for BTEX. Hazard characterization from 28-day feeding study revealed negative effects of potentially toxic BTEX and PAH on organ weight, optimum digestibility and animal growth rate. Sleep time decreased with increasing hydrocarbon concentrations probably due to increased liver enzyme activity.

Comparison of Chicken Manure and Urea Fertilizers as Potential Soil Amendments for Enhanced Phytoextraction of Heavy Metals

ABSTRACT Cadmium (Cd) solubilization in soil and uptake by Mucuna pruriens var. pruriens and Sphenostylis stenocarpa was studied in response to the chicken manure and urea fertilizers application types. In this study, 0.8 g each of the amendments was applied to petroleum-contaminated soil in a pot experiment. Results indicate that the chicken manure application at 14 days before planting gave significantly higher shoot dry matter than its urea counterpart under conditions of Cd stress. Chicken manure application resulted in less Cd solubilization as compared with urea fertilizer dosing. The chicken manure application also significantly increased the shoot Cd accumulation despite its lesser effect on Cd solubilization; thus, it is expected to minimize the risk of groundwater contamination. Chicken manure amended treatment showed greater Cd tolerance for the two species investigated and S. stenocarpa did not support Cd phytoextraction. Although the amendments gave marked reduction in Cd phtotoxicity, those of the urea fertilizer gave only rapid, but short, growth support.

Conditioners and significance of t-RFLP profile of the assemblage of prokaryotic microorganisms in crude oil polluted soils

Following an increased interest in management practices designed to reduce posed phytotoxicity during phytoremediation experiments, crude oil polluted soil and variants from conditioners-aided phytoremediation experiment were subjected to terminal restriction fragment polymorphism (t-RFLP) to evalute the biodiversity of bacterial microflora of polluted soil and amendments conditions. Genetic fingerprinting showed that hydrocarbons stress led to depletion of the genetic resources of soil microflora and to a radical change in its qualitative composition. The amended stressed soils not only has a greater number of species present, but the individuals in the community are distributed more equitably among these species. Non-uniform marginal regain of community was clear with applied conditioner. Positive associations, however were observed with conditioner and phyto-assisted clean-up attempts. Keywords: Crude oil pollution, soil conditioners, microbial diversity, phytoremediation, environment African Journal of Biotechnology , Vol 13(44) 4220-4225

Nutrient Profile of a Contaminated Soil Phytoremediated by Centrosema pubescen and Mucuna pruriens

ABSTRACT Soil nutrients contribute to ecosystem-level processes and are important for productivity, community structure, and fertility in terrestrial ecosystems. Crude oil–stressed agricultural soil was subjected to phytoremediation for 12 weeks, and the nutrient status thereafter was characterized to investigate the inherent effects on such soils in relation to nutrient mineralization and community shifts. Manure additions significantly increased Mg, Na, NO3-N, PO4 −, and SO4 2− contents along with pH values. Accumulated biomass and leaf area measurements were used to monitor nutrient cycles upon amendment addition. Experimental results indicate that after 90 days, the biotreatment had significantly higher levels of monitored nutrients (above 2500 mg/kg NO3-N) than the unplanted control (<500 mg/kg NO3-N), and compared well with the uncontaminated control. The results from this study highlighted inherent advantages of phytoremediation as a soil cleanup technique in terms of soil quality recovery and preservation.

Evaluation of soil microbial communities as influenced by crude oil pollution

Impact of petroleum pollution in a vulnerable Niger Delta ecosystem was investigated to assess interactions in a first-generation phytoremediation site of a crude oil freshly-spilled agricultural soil. Community-level approach for assessing patterns of sole carbon-source utilization by mixed microbial samples was employed to differentiate spatial and temporal changes in the soil microbial communities. Genetic diversity and phenotypic expressions were measured for a more holistic perspective. The 5’- terminal restriction fragments generated after Csp digestion of 16S rRNA gene correlated with observed DNA concentrations in the community profile and revealed loss of diversity with pollution. Crude oil pollution significantly reduced phosphomonoesterases and respiratory activities and values were pH dependent. There were no expressed dehydrogenases activity in initial spill site but were enhanced with phytoremediation. Factor analysis of predictors and independent variables indicates that respiratory, alkaline phosphatase and â-glucosidase activities could be used to explain underlying factors. Positive soil – microbes - plant interactions were observed. Key words : Species diversity, impact of crude oil pollution, soil – biota interactions, ecosystem monitoring, genetic diversity.

Essential Oil and Fatty Acid Constituents of Buccholzia coriacea (Wonderful Kola) Seeds Harvested in Nigeria

Background: The medicinal and therapeutic potentials of plants have long been credited to the observed bioactive compounds inherent in them. Main body: Essential constituents of seeds of Buchholzia coriacea were investigated. Essential oil was extracted using dichloromethane and analyzed with GC-MS while those of fatty acid was using a TRACE Ultra GC-MS. Sixteen compounds were identified which amounted to 100% of the total oil composition. Major compounds in the oil were 1,2-benzenedicarboxylic acid and mono (2-ethylhexyl)ester (74.88%). Other constituents include Hexanedecanoic acid methyl esther (3.22%), 9-Octadecenoic acid, methyl ester (3.08%), Dibutyl Phthalate (2.53%), 1,2-benzene dicarboxylic acid, butyl ester (2.52%), 9-Octadecadienoic acid (Z,Z)-methyl ester (2.51%) and Octadecanoic acid methyl ester (2.21%). Fatty acid profiling revealed ten fatty acids in this order: Pentadecanoic acid>Oleic acid>Palmitic acid>Linolenic acid>Lauric acid>Margaric acid>Linoleic acid>Palmitoleic acid>Mystic acid Conclusion: Identified compounds contributes beneficial roles in human health and have been considered as new source for different supplement and curative for many ailments with low risk for resistance development by pathogenic microorganisms due to natural origin.

Interaction of Selected Minerals with Organic Pollutants: Effects of Phyto-Assisted Bioremediation Using Vigna Subterranea

Soils contaminated with hydrocarbons are a serious problem in Nigeria and 70% of such soils are distributed in the Niger Delta. This pot experiment was conducted to determine the interactions of selected soil minerals with organic contaminants from oil spill site. V. subterranean, which potential for stimulating the biodegradation processes of petroleum hydrocarbons was established was employed under the application of two fertilizer types. Iron concentrations were greater than maximum permissible levels, MPL for plants grown in contaminated soil and showed significant variation (p > 0.05) compared to control. Poor zinc concentrations in oil –stressed regimes decreases ear size, slowed growth and maturity of specie. Both iron and manganese became less available at pH > 7 in the absence of organic matter and water (dehydrated due to oil – stress). Concentration of available P was sensitive to soil pH and was more available to Poultry manure – amended soil as pH correction was evident. Plant tissue analyses revealed significantly (p ≤ 0.05) higher increases in accumulation, in comparison with those grown in unpolluted (Control) regimes. Also, soils depleted mineral nutrients were replenished (> 30%) by test plant and best practice. These results indicated that soil minerals affect the dynamics and transformations of organic materials and metabolic processes even in a stressed soil type with modifications due to clean-up.

Physico Chemical Properties and the Antinutrient status of a non-Alcoholic Beverage (Coke)

The physicochemical properties and the antinutrient status of the beverage, coke were evaluated to determine its suitability for consumption and toxic levels in mammal. The mean levels of nitrates, total nitrogen, chloride, ammonia, tannin, cyanogenic glycosides and caffeine in the samples were (mg/l): 0.008 ± 0.001, 150.000 ±3.446, 11.000 ± 0.686, 183.000 ± 3.019, 0.016 ±5.976, 0.020 ± 0.010 and 0.146 ± 0.002 respectively. The pH of the samples gave a mean value of 3.500, while the mean metal concentrations gave (mg/l) - 0.990 ± 0.099 (Mg); 38.030 ±0.050 (Na); 1.400 ±0.114 (Fe); 0.650 ± 0.014 (Zn); 0.080 ± 0.005 (Mn); 4.720 ± 0.016 (K) and 10.120 ± 0.094 (Ca). Toxicological test using whister albino Rats, shows that the beverage was relatively safe. Generally, the results shows that the antinutrient status of the beverage fell within the standards adopted by most countries. Similarly, the other parameters fell within natural background level although few fell above WHO specifications.