ABSTRACT
This study has been
undertaken to investigate the physicochemical properties and the bacterial
population of the rhizosphere of Sorghum vulgare. In order to simulate spillage,
0.2, 0.9 and 5.0
v/w concentrations of crude oil were used to
contaminate soil sown with seeds of Sorghum vulgare, while the
control had no crude oil contamination. 0ne hundred and twenty days after contamination,
the physicochemical properties and bacterial population of the rhizosphere were
analyzed using standard techniques. Results showed that 5.0 % v/w of crude oil
used in this study caused significant (P<0.05) increase in soil pH, soil
temperature, bulk density and total petroleum hydrocarbon while moisture
content, sand particle, exchangeable cations and total organic matter were
significantly (P< 0.05) reduced when compared with all the other treatments.
These physicochemical conditions may suggest low fertility and could have been
as a result of 5.0 % v/w concentration of crude oil used to simulate pollution.
Soil treated with 0.9 % v/w concentration of crude oil gave highest increase in
soil electrical conductivity, silt particle, exchangeable bases such as Na+, Ca2+, Mg2+ and K+, total nitrogen and
bacterial population when compared with all the other treatments and
significant decrease in total petroleum hydrocarbon when compared with all the
crude oil treated samples. This suggests that there was synergistic cooperation
between roots of Sorghum vulgare and rhizospheric bacteria which may
have facilitated removal of petroleum hydrocarbon and improved the
physicochemical conditions and bacterial population of the soil treated with
0.9 % v/w concentration of crude oil. Hydrocarbon-utilizing bacteria isolated
from the crude oil contaminated rhizosphere of Sorghum vulgare were Pseudomonas
sp., Bacillus sp., Klebsiella sp. and Streptomyces sp.
TABLE OF CONTENT
Title page
List of Tables
List of figures
Abstract
Table of Content
CHAPTER ONE
1.0 Introduction
1.1 Crude oil pollution of ecosystem
1.2 The physicochemical properties of rhizosphere
1.3 Rhizosphere microflora
1.4 Bioremediation of contaminated soil
1.4.1 Land farming
1.4.2 Bioreactor
1.4.3 Composting
1.4.4 Land filling
1.4.5 Biopilling
1.4.6 Biostimulation
1.4.7 Bioaugumentation
1.4.8 Phytoremediation
1.4.9 Rhizodegradation of crude oil contaminated soil
1.4.10 Role of microorganisms in rhizodegradation
1.5 Rhizospheric microorganisms associated with phytoremediation
1.6 A brief in Sorghum vulgare
CHAPTER TWO
2.0 Literature review
2.1 Effects of crude oil contamination on physicochemical properties of rhizosphere
2.2 Effects of crude oil contamination on plants
2.3 Effects of crude oil contamination on rhizospheric microorganism
2.4 Phytoremediation efforts by Sorghum vulgare and related plants
CHAPTER THREE
3.0 Materials and Methods
3.1 Soil pH
3.2 Soil electrical conductivity
3.3 Soil temperature
3.4 Soil bulk density
3.5 Particle distribution
3.6 Cation exchange capacity
3.7 Total petroleum hydrocarbon
3.8 Moisture content
3.9 Total organic carbon and total organic matter
4.0 Total nitrogen
4.1 Total hydrocarbon-utilizing bacteria
CHAPTER FOUR
Results
CHAPTER FIVE
Discussion and Conclusion
REFERENCES
CHAPTER ONE
1.0 INTRODUCTION
The inevitable and disastrous consequence of crude oil pollution for the biotic and abiotic components of the ecosystem has been a major source of concern to the government and people living in oil producing and industrialized countries. This had led to ethnic and regional crises in the Niger Delta region that generated significant tension between them and the multinational oil companies operating in the region (Vidal, 2010).Crude oil exploration, production and transportation in the Niger Delta region have increased tremendously since its discovery in Nigeria in 1956 and has become a veritable source of economic growth and the main stay of the Nigerian economy (Okoh, 2006).The global scale of oil production is staggering and its demand is in the order of 3.25 x 109 tones or 3.8 x 1012 liters per year and much of it is transported thousands of kilometers before it is used (Prince and Lessard, 2004).
Crude oil is a complex mixture of organic compounds including volatile aromatic fractions and less volatile aliphatic fractions. The main constituents of crude oil are the elements hydrogen (10 – 40%) and carbon (83 - 87%). Various types of crude oil contain small quantities of sulphur, nitrogen, oxygen and trace metals such as vanadium, nickel, iron and copper which are not usually found in refined petroleum (Atlas and Bartha, 1973). Individual chemical composition of each crude petroleum however, depends on its origin and location and has a unique mixture of molecules which defines its physical and chemical properties. Crude oil has been part of the biosphere for millennia and has been used since ancient times in one form or the other and has risen in importance due to rise in commercial aviation, invention of internal combustion engines and the increasing use of pesticides, fertilizers and plastics which are mostly made from oil (Okoh, 2006).
Soil is an extremely complex, dynamic and living medium, formed by mineral particles, organic matter, water, air and living organisms. It establishes the interface between earth, air and water and performs many vital functions. The importance of soil for the survival of plants has become apparent due to numerous services it renders, ranging from filtration of ground water, removal of pathogens, degradation of organics, recycling of nutrients on which agriculture thrives and provision of raw materials for industries which are of economic value. Human activities such as the production, transportation, storage and sometimes vandalization of oil facilities accidentally release large quantities of crude oil and its fractions to marine and terrestrial environments thereby posing a long term threat to the soil and the services it renders (Blum, 1997).
Crude oil is a fossil fuel derived from ancient fossilized organic material. The fossilization processes include the initial process of diagenesis and the final or completion process called catagenesis. The initial process of diagenesis occurs at temperatures at which microbes partially degrade the biomass and result in dehydration, condensation, cyclisation and polymerization of the biomass. Subsequent burial under more sediments at higher temperature and pressure allows catagenesis to complete the transformation of the biomass to fossil fuel by thermal cracking and decarboxylation (Prince and Lessard, 2004).....
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