BOTANY PROJECT PDF | SEMINAR PROJECT TOPICS IN BOTANY ON EFFECTS OF SIMULATED CRUDE OIL CONTAMINATION ON THE PHYSICOCHEMICAL PROPERTIES AND BACTERIAL POPULATION OF RHIZOSPHERE OF SORGHUM VULGARE PERS. https://emrislot.com/product/botany-project-pdf-seminar-project-topics-in-botany/
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). BOTANY PROJECT PDF | SEMINAR PROJECT TOPICS
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). BOTANY PROJECT PDF | SEMINAR PROJECT TOPICS
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). BOTANY PROJECT PDF | SEMINAR PROJECT TOPICS
1.1 CRUDE OIL POLLUTION OF THE ECOSYSTEM
The release of crude oil and its fractions into the natural environment has adverse ecological impacts on both terrestrial and aquatic ecosystems. In Nigeria, it has been reported that, annually an estimated quantity of 2,105,393 barrels of oil was spilled on land, coastal and offshore marine in the Niger Delta region between 1976 and 1990 (Kontagora, 1991). The impact of oil exploration and exploitation on the environment is one of the inevitable consequences of industrialization and economic development in Nigeria (Osuji and Onojake, 2006). In aquatic ecosystem, crude oil floats and blocks out sunlight, thus initiating the death of phytoplanktons and seaweeds, which are at the base of the aquatic food chain, thereby starving organisms that depend on them. Crude oil also has become one of the most frequently detected underground water pollutant caused by leakages from underground tanks, pipelines and other components of crude oil distribution (Kharoune et al., 2001; Gwendoline, 2010). Soil soaked with crude oil loses fertility and initiates environmental degradation and ecological succession. Crude oil pollution changes the composition of soil microorganisms and alters the physicochemical properties of the soil rhizosphere which affects plant growth and development (Gesinde et al., 2008; Ebere et al., 2010). BOTANY PROJECT PDF | SEMINAR PROJECT TOPICS
1.2 THE PHYSICOCHEMICAL PROPERTIES OF RHIZOSPHERE
The physicochemical properties of rhizosphere are the physical and chemical characteristics of the soil surrounding plant roots, which differ from those of the bulk soil. Such properties include soil texture, soil porosity, bulk density, cation exchange capacity, mineral composition, soil organic matter, soil pH, soil water or moisture content (Luthy et al., 1997; Gogoi et al., 2003). Densification of soil particles due to crude oil contamination gives rise to compaction, formation of organic ligands and binding of clay particles. This leads to increase in soil bulk density, low soil porosity and low soil moisture content (Xu and Johnson, 1995). Moisture level affects soil respiration, nutrient transport and availability and hence limits the metabolism and growth of microorganisms in the soil (Smith et al., 1998). The growth rate of microorganisms on crude oil contaminated soil is limited by the availability of nutrients such as nitrogen and phosphorous (Pritchard and Costa, 1991). The rate of microbial growth depends on soil pH. Soil pH is a critical factor for microbial growth and survival. Different microbial strains exhibit their maximum growth potential in a limited pH range. Soil pH value near neutral is suitable for growth of diverse bacterial population (Barua et al., 2011). BOTANY PROJECT PDF | SEMINAR PROJECT TOPICS
1.3 RHIZOSPHERE MICROFLORA
Rhizosphere is the zone of the soil surrounding the root of plants where the biological, physical and chemical properties of the soil are greatly influenced by the roots (Frick et al., 1999). It is the soil matrix and can be described as the longitudinal and radial gradients occurring with expanding root growth, nutrients and water uptake, exudation and subsequent microbial growth (Uren, 2000). The environment of plant rhizosphere is the most favorable microhabitat for microorganisms compared to the surrounding bulk soil (Bias et al., 2006). The rhizosphere has been reported to harbor more oil utilizing bacteria than adjacent non rhizospheric soil (Sorkhoh et al., 2010). Microorganisms commonly associated with the rhizosphere are Pseudomonas sp., Bacillus sp., Sphingomonas sp., Streptomyces sp., Micrococcus sp., Aspergillus sp.and Penicillum sp.(Radwan et al., 1998; Obire et al., 2008). BOTANY PROJECT PDF | SEMINAR PROJECT TOPICS
1.4 BIOREMEDIATION OF CONTAMINATED SOIL
Biomediation is the use of living organisms to manage or remediate polluted soil (Bossert and Bartha, 1984). Bioremediation is the elimination, attenuation or transformation of polluting or contaminating substances by the use of biological processes (Wenzel, 2009). Biomremediation technologies include land farming, bioreactor, composting, landfilling, biopilling, biostimulation, bioaugmentation and phytoremediation (Siciliano and Germida, 1998).
1.4.1 LAND FARMING
Land farming is a waste disposal technology for handling hazardous chemical wastes. It involves simultaneous treatment and disposal. Land farming is a biotechnology application that uses soil aerobic microorganisms to degrade petroleum hydrocarbons and their derivatives to carbon dioxide and water or other less toxic intermediaries (USEPA, 1990).
This is a periodic treatment of contaminated groundwater or industrial effluent, using an engineered bioprocess. Bioreclamation of soil contaminated by petroleum hydrocarbons have been carried out, using bioreactors such as the conventional suspended growth sequencing batch reactors (SBRs), sequencing batch biofilm reactors (SBBRs) and soil slurry sequencing batch reactors (SS-SBRs). These bioreactors boost the population of petroleum degrading microorganisms and thus increate bio-oxidation rate of the pollutants (Irving and Ketchum, 1983).
This technology, which seems to operate more under thermophilic conditions, is used mainly for bioremediation of resistant (recalcitrants) chemicals and explosives such as 2,4, 6, trinitrotoluene (TNT). The approach of this technology is mixing of the hazardous chemicals with the soil and the compostable materials before treatment (USEPA, 1990).
1.4.4 LAND FILLING
Land filling is an engineered and controlled treatment operation on land. The procedure is technically simple, less costly and easily managed. Generally, the waste is spread out in layers (in a pit) and compacted down using either a tractor or landfill compactor. The compacted waste, which may be about 2.4m thick, is eventually covered with inert material (USEPA, 1994).
This requires heaping or piling up of the pollutant in an enclosure such as tunnel or greenhouse structure or on top of a liner. The “treatment’ heap can be aerated from time to time either by tilling or by forcing air through perforated pipes installed at the base of the heaps (Balba et al., 1991).