form a very dense network of north-south drainage systems. The Benin Formation ...... Butterweth Heineman, Stoneham, Mass 14-32 pp. Ayodele, O. J. (1980).
EFFECTS OF OIL SPILLAGE ON SOILS NUTRIENTS OF SELECTED COMMUNITIES IN OGONILAND, SOUTH-EASTERN NIGER DELTA, RIVERS STATE, NIGERIA
By
OTAIKU, AJAYI AYODELE 2000/PGD/PH/016/ENV
DEPARTMENT OF GEOGRAPHY AND METEOROLOGY, FAULTY OF ENVIRONMENTAL SCIENCES, ENUGU STATE UNIVERSITY OF SCIENCE AND TECHNOLOGY, ENUGU STATE, NIGERIA FOR THE AWARD OF POSTGRADUATE DIPLOMA IN ENVIRONMENTAL MANAGEMENT
August, 2004
1
CERTIFICATION
This is to certify that this project work was carried out by Ayodele Ajayi OTAIKU, with Matriculation number
2000/PGD/PH/016/ENV
of the Department of Geography
and Meteorology, Faulty of Environmental Sciences, Enugu State University of Science and Technology, Enugu State, Nigeria for the award of Postgraduate Diploma in Environmental Management
Signed----------------------------------------
Date………………….
Project Supervisor Chika Igwe B.Sc. (Biochem), UNIPORT. M. Phil. (Env. Mgt.), RUST Ph.D (Env. Mgt., Inview), RUST.
Signed ……………………….
Date…………………
IWUEKE N.T. (MRS) Head of Department, Department of Geography and Meteorology.
Signed ………………………
Date…………………
PROF. A. NNAMIGWE, AGU Dean of Faculty Environmental Sciences
2
DEDICATIONS
To My Teachers for giving out all the Knowledge I need for Life and Living. My appreciation goes to my entire family for their patience and encouragement during the course of this study and my little angel Faith Alao and her Late brother Fellowboy Alao.
Nigeria, West Africa
3
ACKNOWLEDGEMENT
I express my profound gratitude to my supervisors for their contributions to the success of this work.
I appreciate the contribution of Mr. Chika Igwe, my
supervisor for his guardian, help and support at every stage of this work. Many thanks to my co-supervisors, Prof. B.A. Oso, Botany and Microbiology, University of Ibadan, Nigeria, and Dr. Oluwwole Fatunbi (I.I.T.A).
I acknowledge Mr. Yellowe of Rivers State Polytechnic, Bori, who assisted to establish the field survey in all locations. Many thanks to Tola Bhadmus, Sumbo, Osaki Dabibi, Johnson, Kofi, Kwame, Kunle Akinbami, Niyi Oyatokun, Rev. Fr. Austin, Donatus Ngidi (ESUT) , and Kenny (my colleague).
My unreserved appreciation goes to my mentors: Mrs Bisi Akinbami , Mrs Bola Akinfala, Seye Solabomi, Yomi Akinwale, Rev. Joe Uwareme, Pastor and Mrs Alao, Prof. Pat Utomi, Prof. B.J. Olufeagba, Chief Bayo Ojo (SAN), Dr. (Mrs.) G. Ekpenyoung, Yetunde Akinwale,
Dr. A. F.Abimbola, and Mr.
Andrew Omonbude for being a very valuable adviser in my career development and the enterprise model of my work.
Finally, my appreciation goes to my entire family for their patience and encouragement during the course of this study. Special thanks to Ayomide Bamiro, who discovered me, for her tireless support during the course of this study and my little Faith Alao.
4
ABSTRACT Oil spill and other exploration activities destroy biodiversity complex that maintain ecosystem stability. Crude hydrocarbons are inhibitory to plant growth in polluted soils (Ultisols) in selected communities (Zaakpon, Kpean, Yorla and Gure) at 0-30 cm depths in Ogoniland resulting to destruction of farmland, Acid rain, contamination of water supply sources, loss of job by the locals and health hazards in Niger Delta, Nigeria . The chemicals and physical properties of polluted soils were determined with its least significant value in relation to its macronutrients and micronutrients.
The toxic effects have been found to be generally localized between 0-15cm depths of the impacted soils with low organic matter contents (< 1% Org. Carbon).High C/N ratios in Gure (11.58), Zaakpon (52.95) and Kpean (25.49) will results to low microbial activity; and hence, require soil inoculation to enhance oil-degrading bacteria. Yorla with low C/N 8.66 will have a very satisfactory rate of nitrification and contribute to the organic matter pool.
Usually the bacterial community is adapted to the presence of the contaminants for energy and metabolic activities, but other environmental conditions such as nutrients availability and oxygen concentration may be unfavourable to in situ bioremediation treatments. These will require bioaugementation or biosimulation for soil nutrients enhancement for biodegradation and restoration ecology of hydrocarbon polluted sites. The impacted soils fertility analyses of crops tolerant to nutritional imbalance of the study area are: maize, banana, cassava, mango, pineapple, sweet potato and tomato base on their critical nutrient concentrations of the crops yield. The bioenergy crops cultivated on post-remediated soils have potential for ethanol production in the Niger Delta region for jobs and wealth creation.
5
CONTENTS Title Certification
2
Dedication
3
Acknowledgement
4
Abstract
5
Table of Contents
8
List of Figures
9
List of Plates
10
Chapter One 1.0 Introduction
11
1.1 Background
12
1.2 Statement of the Problems
12
1.3 Objective of the Study
14
1.4 Significance of the Study
14
1.5 Theoretical Framework
17
1.6 Scope of Study
17
1.7 Limitations
18
1.8 Definitions of Terms
18
1.9 Definition of Terms
18
References
22
Chapter Two 2 Literature Review: Ecological Setting
25
2.1 Geography, geomorphology and drainage
25
2.2 Climate of the study area
27
2.3 Soils of the study area
28
6
2.3.1 Native Soil Nutrient
30
2.3.2 Soil Nutrient Type
32
2.3.3 Agriculture
35
2.4
38
Assessing Oil Spill Damage
References
40
Chapter Three 3 Materials and Methods
43
3.1 Research Area
44
3.2 Soil Sampling and Analysis
44
3.3 Results
45
References
46
Chapter Four 4 Results and Discussion
48
4.1 Native Soil Nutrients
49
4.2 Impacted Soil Nutrients
49
4.2.1 Soils Chemical Properties and Hydrocarbon Pollution
45
4.2.2 Comparative Effects of Depth on Impacted Soils
55
4.2.3 The effects of Hydrocarbon Pollution on Physical Soil Properties 4.2.4 Critical Nutrient Concentration
56
4.2.5 Carbon/Nitrogen Ratio of the Study Area
67
References
70
59
Chapter Five 5 Conclusions and Recommendation
78
Bibliography
85
7
LIST OF TABLES
Table
1.
Page
The effects of hydrocarbon pollution on the soils and its chemical properties
51
2.
Particle size distribution of the soils of the experimental location 57
3.
Organic Carbon % (Org. C %) or the study area
68
8
LIST OF FIGURES Figure
Page
1.
Geological map of southern Nigeria, showing the study area: Ogoniland
26
2.
Geological map showing the study area locations Ogoniland (Gure, Kpean, Zaakpon and Yorla)
27
3.
Nigeria Oil and Gas pipeline , Niger Delta, Pipeline density showing potential sources of oil spill sites in the Niger Delta
29
4.
Soil Logs , from Nsioken Agbi Ogale, Eleme L.G.A and similar to Ogoniland, Niger Delta, Nigeria
30
5.
Communities in Niger Delta, Nigeria Kids playing with exposed oil pipes outside a home in Nigeria's Niger Delta region. Photo: © Michael Fleshman All Rights Reserved. Taken from internet site December 1, 2003
5
Ecological and forest areas of the study area -Niger Delta
34
36
6
Comparative effects of hydrocarbon pollution on the soils pH, organic carbon, total nitrogen and available phosphorus on the study area. Bars represent Standard Error
52
7.
Comparative effects of hydrocarbon pollution on the soils exchangeable cations at same selected sites in Ogoniland. Bars represent Standard Error (SE)
53
8.
Effects of pollution on plant and essentials heavy metals in selected communities in the study area
54
9.
Hydrocarbon pollution effects on the particle size distribution of the study area
58
10.
Showing Carbon/Nitrogen ratio of the study area
59
9
LIST OF PLATES Plates
Page
1.
Environmental Impacts of hydrocarbon pollution on the biological diversity with the community. This requires a challenge for a new solution
12
2.
Communities in Niger Delta, Nigeria 34 Kids playing with exposed oil pipes outside a home in Nigeria's Niger Delta region. Photo: ©Michael Fleshman All Rights Reserved. Taken from internet site December 1, 2003
3.
While fishing was once a prime activity in Ogoniland, it was evident from community feedback and field observations that it has essentially ceased in areas polluted by oil
37
4.
Children view of gas flaring, Niger Delta
39
10
CHAPTER ONE 1.0 Introduction 1.1 Background Soil contamination with hydrocarbons causes extensive damage of local ecosystems since accumulation of pollutants in animals and plants tissues may cause progeny’s death or mutation (Autry and Vogel, 1991). Organic contaminants (e.g., Polychlorinated biphenyls (PCBs), Polycyclic aromatic hydrocarbons [PAHs] other than pesticides can enter into the soil from fuel combustion or from sewage sludge and other feedstocks (Edwards,1983; Fries, 1982;O’Connor, 1998). These contaminants from sludge additions to land may persist in soils or contaminate forage on which livestock graze (Wilson et al., 1997). Spillage of fuel oil hydrocarbons can contaminate soils. These hydrocarbons will inhibit seed germination and plant growth, but plants do not appear to accumulate the hydrocarbons. Fuel oil hydrocarbons are inhibitory to plant growth (Chaîneau et al., 1998).
Petroleum hydrocarbons are naturally occurring chemicals used by humans as a source of energy for various kinds of activities. Natural gas, crude oil, tars and asphalts are types of petroleum deposits, these compounds are hydrocarbons that are ultimately composed of various proportions of alkanes (e.g. methane, ethane, propane), aromatics (e.g. benzene, toluene, ethylbenzene, and zylene, collectively known as BTEX), and polycyclic aromatic hydrocarbon (Lyons, 1996). Contamination of soils by hydrocarbon occurs by the vandalization of the oil pipelines and mechanical failure during petroleum exploration operation in host communities where oil is found. Soil, a heterogeneous made ups of inorganic solids, organic ( humic) solids gases, and liquids (Paul and Clark, 1989). When strange substance enters the soil, myriads of changes takes place which could modify its physical, chemical and biochemical state.
11
All these hazards are to the detriment of farmers and fishermen in the neighbourhood. Apart from these direct effects, the toxic soil affects plants by creating conditions which make essential nutrients such as nitrogen unavailable to plants (Idoniboye-Obu, 1994).On a micro-scale, these transformations can result in the partitioning of the contaminant within the soil matrix. The contaminant may be distributed as a gas in the soil atmosphere, dissolved in pure water, or associated with the soil particles as well as in the form of free product.
Plate 1. .Farming and cropping systems showing land use in Ogoniland, Creek leading to leaking well head 18, at Kpor, Ogoni. July 9, 2004, Niger Delta, Nigeria
1.2 Statement of the Problems Metal availability in soils depends on many factors, such as cation exchange pH, and plant species (Soon and Bates, 1982; Davies, 1992; Smith, 1994). The metals in soils vary considerably in their chemical reactivity and bioavailability. In addition the noise, gas emission and smoke which result from oil spills create further hazards to flora and fauna in the environment. Also, mention need be made of the amount of rural land which is lying unused along the right of way created for oil pipelines, despite the fact that entire Niger Delta region of Nigeria is short of
12
good agricultural land because of its ecological condition. This shortage is worsened by the huge amount of land taken by the
criss-cross oil pipelines
(Idoniboye - Obu, 1994).
Fate and Transport The behaviour of spilled oil is different on land and in water. Typically 1gm of oil on water surface will ultimately cover 1-10m2 thereby favouring the loss of at least 25-3% of the spill by evaporative and photooxidative processes (Berridge et al., 1986). In contrast, a rapid vertical infiltration is observed in soil, unless this is prevented by freezing of water saturation. Therefore, on land only about 1 - 2% of the spill may be got rid of by natural process (McGill et al., 1981). It is, however clear, that the already spilled petroleum hydrocarbon are difficult to deal with the treatment of contained oil wastes (i.e., those coming in the effluent plants) is practically feasible.
The release of BTEX’s to the environment is influenced by their fate and transport mechanisms. The BTEX appearance in soil and groundwater and
its ability to
be remediated is affected by volatilization, dissolution, sorption and degradation by micro-organisms. Volatilization will affect the actual concentration of BTEX’s. When analyzing a petroleum contaminated site is that some of the petroleum will volatize
the first thing that will happen
due to the high solubility, the
relatively low molecular weight and the high vapor pressure (Bedient, 1994).
Legally acceptable oil waste disposal methods are: Incineration, deep well injection, burial in a secure chemical landfill, or land treatment (land farming). The ‘land farming’ process uses the activity of soil microorganisms to degrade or immobilize various components of hazardous waste materials.
Organic
compounds are converted to mineral constituents and humus, and heavy metals are bound or precipitated (Sahastrabudhe and Modi, 1986).
13
Most importantly, the material used must be biodegradable and the facility should be established in areas where the climate is at least seasonally favourable for activity of microorganisms. Operationally, the biodegradation process needs to be optimized through fertilization (N, P) pH control (liming) and tilling. The short term environmental fate of the hard-to-degrade hydrocarbons seem to be humification, rather than complete mineralization to CO2. The humus content of land farmed soil has been found to increase significantly (Kancannon, 1972). Land farming of oily sludges is being practiced at numerous sites, generally with satisfactory results (Bartha, 1986).
1.3 i.
Objectives of Study To determine the effects of hydrocarbon pollution on the chemical properties of soils.
ii.
Comparative effects of depths on impacted soils nutrients of selected sites (Ogoniland).
iii.
The particle size distribution of soils in the study area.
iv.
The critical nutrients concentration adequate for growth for selected crops.
v.
Carbon/Nitrogen ratio for selected crops in the study area .
vi.
To recommend possible solutions for remediation and agro-ecology base on research finding.
1.4
Significance of the Study
The elucidation of oil spillage effects on Ogoniland, South-eastern, Niger Delta will allow for a realistic planning of future industries which will minimize that impact of petroleum exploration on the environment. The soils capacity to provide crops with nutrients and the maintenance of its physical conditions to optimize yields are the principal factors in maintaining soil fertility and determining the productivity of an agricultural system (Smith, 1992).
14
Four bacterial genera were identified in the bacteria consortium (BC) named, Pseudomona, Serratia, Acinetobacter and Flavobacteria, most of them have reported as hydrocarbon utilizers (Atlas, 1981). The deficiency of available nitrate nitrogen often observed as being reported by the local farmers in their low produce may be caused by an inadequate population of nitrate oxidizer. Several studies have been carried out to identify the ecological impact of oil exploration, drilling and spills (Abe and Ayodele, 1983; Envir-Health Consultant, 1995). These studies have shown that oil exploration, drilling and spills destroy vegetation during the process.
Symptoms of nutrient deficiencies and toxicities result from impaired metabolism with the plant. Impaired growth and eventual death of crop plant are the major symptom of nutrient deficiency and toxicology experienced by plant established on a petroleum soil. Herbert et al., (1993) have demonstrated that the presence of colloidal organic matter within the soil solutions could significantly increase transport of hydrophobic poly-aromatic hydrocarbons (PAHs).
The form and quality of nutrient accumulated within a plant is often influenced by the supply of that nutrient. Thus, nitrate-N may accumulate in plants well supplied with nitrogen and enable useful diagnostic criteria to be established based on nitrate-N rather than total-N (Ulrich et al., 1959; Papastylianou and Puckridge, 1981). Such phenomena as sorption of contaminants onto soil materials can have profound effects on the final distribution of the material within the environment. Sorption of hydrophobic organic contaminants to soil surfaces, organic matter and humic materials has been shown to have variable effects on the mobility of the contaminants within and through a soil system (Baker and Herson, 1990).
15
Availability of nutrient form biological activities depends largely on nutrient supplies and limitations (Binkley and Vitunsek, 1989). Soil Organic matter (SOM) is primarily about 58 %C by weight with a large reservoir of essential plant nutrient contained in it. SOM is also generally associated with finer and more reactive clay and silt fraction of soil. Its proximity and concentration near the soil. This makes the erosion of the SOM a strong indication of the overall plant nutrient losses resulting from soil erosion thus the effectiveness of soil conservation practices can also be based on the amount of SOM (Follet et al., 1990).
Plant residues (crop) are often seen as materials that can be used for the maintenance of soil organic matter (SOM). The rates of the decomposition of the plant materials in the tropics are much high compared with those of the temperate region. The plant residue decomposition and the mulching effect on the soil micro climate are functions of the plant residue quality (Xu et al., 1983). Plant materials or residue having high C/N ratio, high liquid and polyphenol will decompose slowly thereby enhancing accumulation of SOM when compared with materials of low C/N, lignin and polyphenol (Tian et al., 1993). The management of plant residues may therefore influence the soil nutrient status.
High crop yields can be obtained with the use of chemical fertilizer, but the use of such has not been widely feasible due to socio-economic reasons. Furthermore, continuous use of nitrogen (N) fertilizer can result in soil acidification (Jones, 1976). Generally, crop residue do affect the soil condition and crop performance through the following means: Organic matter replenishment, nutrient cycling, increased availability of N, improved moisture retention, improved mater infiltration rate, improved soil structure, protection against soil erosion etc (Allision, 1973).
16
1.5 Research Statement and Hypothesis i.
The Carbon-Nitrogen ratio will determine the extents of biodegrability in the polluted soils.
ii.
Contaminants are often potential energy sources for microorganisms.
iii.
Biostimulation will be required for complete biodegradation at the pollution soils.
1.6 Theoretical Framework Environmental Factors Microbial populations capable of degrading contaminants in the subsurface are subjected to a variety of physical, chemical, and biological factors that influence their growth, their metabolic activity, and their very existence. The properties and characteristics of the environments in which the microorganisms function have a profound impact on the microbial population, the rate of microbial transformations, the pathways of products of biodegradation, and the persistence of contaminants.
Physical–Chemical Factors The activities of microorganisms are markedly affected by their physical and chemical environment. Environmental parameters such as temperature, pH, moisture content, and redox potential will determine the efficiency and extent of biodegradation.
Agro-Ecology The critical nutrient concentrations of crops yield combined with the soil physical and chemical properties could be a useful diagnostic tool for soil amendment in crop production in the impacted sites after remediation.
17
1.7
Scope of Study
i.
Types of soil and the conditions present and native and impacted soils.
ii.
Possibility of using bioremediation technologies for cleans up the contaminated sites as a function of Carbon / Nitrogen ratio of soil nutrient.
iii.
Type of crops to be grown on clean up sites base on their critical nutrients concentration and crops yield.
1.8
Limitations
The present work aims at identifying under what optimized conditions (physical and chemical properties) in the polluted soils will biodegradation takes place for effective pollutant mineralization to CO2 and H2O. Also, the critical nutrient concentration required to optimize crops yield in the polluted soils. What clean-up methodologies will be required to remediate contaminated land and bioremediation technique applicable are the limitations.
1.9 Definition of Terms Analysis of Variance (ANOVA): A statistical technique that attributes variability in an experiment to treatments or other uncontrolled factors. Aggregate soil: A mass of fine soil particles held together by clay, organic matter, or microbial gums. Aggregates are part of soil structure. Alluvium: A general term for all eroded material deposited by running water including gravel, sand, silt, and clay. Aquifer: Layers of underground porous or fractured rock, gravel, or sand through which considerable quantities of groundwater can flow and which can supply water at a reasonable rate. May be classified as perched, confined, or unconfined. Biodiversity: Biodiversity is the complex of all living things in a giving ecosystem. It includes fauna (animals), flora (plants) and microscopic organisms. Oil spill and other exploration activities destroy this biodiversity complex that main life.
18
BETEX: Benzene, toluene, ethylbenezene, and zylene, collectively known as BETEX. Biomass: The mass of a specific plant or plant part in a given area, usually expressed as weight or volume per unit area. Biomass: The total weight of all organisms in a particular environment. Bioremediation: The use of biological agents to reclaim soil and water polluted by substances hazardous to human health or the environment. Biodegradation: Microbial catalyzed reduction in complexity of chemicals. In the case of organic compounds, biodegradation frequently, although not necessarily, leads to the conversion of much of the carbon, nitrogen, phosphorus, sulfur, and other elements in the original compound to inorganic end products. Crop nutrient requirement: The amount of nutrients needed to grow a specified yield of a crop plant per unit area. Critical value: a) For interpretation of plant analysis: A nutrient concentration in the plant tissue above which the crop is amply supplied, and below which the crop is deficient. b) For interpretation of soil analysis: A soil test level above which there are enough nutrients to produce an economic or yield goal. Carbon-nitrogen (C: N) ratio: The ratio of the mass of carbon to the mass of nitrogen in soil, organic material, or plants. Cation Exchange Capacity: The amount of exchangeable cations that a soil can adsorb at a specific pH, expressed as centimoles of change per kilogram (cmolc/kg) of soil or milliequivalents per 100 g of soil (meq/100 g soil). Denitrification: The transformation of nitrates or nitrites to nitrogen or nitrogen oxide gas, occurring under anaerobic conditions. Field capacity: The amount of water a soil holds after free water has drained because of gravity. Geomorphology: The sum total of the internal and external modification of the crust (earth) which gives rises to land forms with emphases on climates, geology and time.
19
Humus: Decay-resistant residue of organic matter decomposition. Humus is darkcolored and highly colloidal. Immobilization: The conversion of an element from the inorganic to the organic form in microbial tissues resulting in that element not being readily available to other organisms or plants. Inoculation (bioaugmentation): Inoculation of bacteria with hydrocarbon biodegrading capabilities to influence native microorganism population during bioremediation. In situ bioremediation: The application of biological treatment to the cleanup of hazardous chemicals present in the subsurface. Liming requirement: The amount of liming material required to change the soil to a specific soil pH. Least Significant Difference (LSD): A statistical range test used to determine if results from an experiment are due to treatment effects or uncontrolled factors. Macronutrient: A nutrient that a plant needs in relatively large amounts. Essential macronutrients are nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulphur (S). Micronutrient: Nutrients that plants need in only small or trace amounts. Boron (B), Chlorine (Cl), copper (Cu), Iron (Fe), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), and Zinc (Zn) are considered micronutrients. Mineralization: The conversion of an element by soil organisms from an organic form to an inorganic form. Mobile nutrient: A nutrient that moves readily in the soil or plant medium. N-based nutrient application: The application of nitrogen in sufficient quantities to meet the nitrogen requirements of the crop. Organic matter: Plant and animal material, living and dead. Soil organic matter: The organic fraction of the soil exclusive of undecayed plant and animal residues. Often used synonymously with “humus”.
20
Soil productivity: A measure of the soil’s ability to produce a particular crop or sequence of crops under a specific management system. Soil texture: The relative proportions of sand, silt, and clay in the soil. Surfactant: A material that favors or improves the emulsifying, dispersing, spreading, wetting, or other surface modifying properties of pesticides in solution. Site Characterization: The derivation of a site conceptual model that integrates what is already known about a site, and identifies both what still needs to be discovered, and how that information should be used. Total nitrogen: The sum of the organic and inorganic forms of nitrogen in a sample. Toxicity: Degree to which a pesticide is poisonous; the ability of a substance to interfere adversely with the vital processes of an organism. Wetlands: An area characterized by periods of inundation, hydric soils, and hydrophytic vegetation.
21
References Atlas, R. M. (1981). Microbiol. Rev. 45 (1), 180 Abe F. and Ayodele A. (1983). Oil exploration, drilling and the environment, paper presented at the National Conference on Development and the Environment, NISER (Ibadan). Allinson, F.E. (1973). Soil Organic Matter and its role in crop production. Development in Soil Science, 3 London, Elsevien Scientific Publication and Co. 673p. Alvarez P., Vogel M. (1991).Biodegradation. 2. P. 43. Binkley, D and Vitousek, P. (1989). Soil nutrient availability. In: Pearcy R.W. Ehrleringer, J. Moorney, H.A. and Rundel P.W. (eds) plant physiology ecology Champman and Hall, New York, 75 - 96pp. Berridge, S.A., Thew, M.T., and Loriston – Clarke, A.G. (1968). In: Scientific Aspects of Pollution of the sea by oil”. (Hepple, P.Ed.), Institute of Petroleum, London, pp 35. Bedient,
Philip
B.
(1994).
Groundwater
Contamination,
Transport
and
Remediation, Prentice Hall PTR. Chaîneau, C.H., Morel, J.L., and Oudot, J. (1998) Phytotoxicity and plant uptake of fuel oil hydrocarbons. J. Environ. Qual. 26, 1478–1483. Davies B.E (1992). Inter-relationships between soil properties and the uptake of cadmium, copper, lead and zinc from contaminated soils by radish (Raphanus Sativus L.) Water Air soil Pollut. 63: 331-342. Envir-Health
Consultants
(1995).
Files
on
Petroleum
exploration
and
Environmental Health hazards (Pers. Comm.). Edwards, N.T. (1983). Polycyclic aromatic hydrocarbons (PAHs) in the terrestrial environment - a review. J. Environ. Qual. 12, 427–441. Fries, G.T (1982). Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land. J. Environ. Qual. 11, 14–20.
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Follet, R.F., Gupta, S.C. and Hunt, P.G. (1990). Conventioned practices: Relations to the management of plants nutrients for crop production. Soil Science Society of America and America Society of Agronomy. Soil fertility and organic matter as critical component of production systems. SSSA. Spec. Publication No. 19, 79p. Idoniboye-Obu, B (1994).Compensation for ecological disturbances and personal losses, paper presented at the conference on marine pollution control, Port Harcourt :Rivers State University of Science and Technology. Kancannon, C.B. (1972). Environmental Protection Agency Publ. No. R2:72 110, United States EPA Washington D.C., U.S.A. Lyons,W.C.(1996).Standard handbook of Petroleum and Natural Gas Engineering Gulf Publishing Company, Houston. O’Connor, G.A. (1998). Fate and potential of xenobiotics. In : Beneficial Coutilization of Agricultural, Municipal, and Industrial By-products. Brown, S., Angle, J.S., and Jacobs, L., Eds. Kluwer AcademicPublishers, Dordrecht, the Netherlands. pp. 203–217. Sahastrabudhe S. and Modi V.V. (1986). In: “Use of Microbes in Environmental Improvement” (Bisen, P.S. CBS Publishers and Distributors, Bhola Nath Nagar, India. 1:1 – 7pp Smith S.R. (1994). Effect of soil pH on availability to crops of metals in sewage sludge-treated soils. Nickel, copper and zinc uptake and toxicity to rye grass. Soon, Y.K and Bates T.E. (1982). Chemical pools of cadmium, nickel and zinc in polluted soils and some preliminary indications of their availability to plants. Int. J. Environ. Anal chem. 35: 241-251. Smith S.R ; and Haby V.A (1971). Simplifies Colourimetric determination of soil organic matter. Soil sci 112:137-141. Tian, G., Kang, B.T. and Brussard, L., (1993). Mulching effects of plant residues with
chemically contrasting composition on maize growth and nutrient
accumulation. Plant and soil 153 : 179 – 187.
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Ulrich, A, Hills, F.J, Ririe, George, A. Cr and Morse, M.D. (1959). Plant analysis a guide for suger beet fertilization. Calif.Agric. exp. St. Bull 766: 3-24. McGill W.B., Rowell, M.J. and Westlake, D.W.S (1981). In: “Soil Biochemistry” (Pau, E.A. and Ladd, J.N. Eds). Dekker, New York 4:229 National Academy of Sciences, (1985). “Oil in Sea”. National Academy Press, Washington D.C. U.S.A. Papastylimou, I. and Puckridge, D. W. (1981).Nitrogen nutrition of cereals in a short term rotation. 11 sterm nitrate as an indicator of nitrogen availability Hust. J. Agric. Res. 32:713-723pp. Wilson, S.C., Alcock, R.E., Stewart, A.P., and Jones, K.C. (1997). Persistence of organic contaminants in sewage sludge–amended soil: a field experiment. J. Environ. Qual. 26, 1467–1477. Xu, Z.H, Myers, R.J.K., Saffigna, P.G and Chapman, A.L.(1993).Nitrogen Cycling in Leucaena (Leucaena leucocephala) alley cropping in the semi-arid tropics. Mineralisation of Leucaena residue. Plant and Soil.148:73–8.
24
CHAPTER TWO 2.0
Ecological Setting: Literature Review
2.1
Geology, geomorphology and drainage
The geology of the study area is of sedimentary origin. They are deltaic in their formation being laid down by River Niger during geological epochs. The subsurface geology of the Niger Delta consist of three lithographic units: Benin (Continental), Agbada (Mixed) and Akata (Marine) which are in turn overlain by various types of sedimentary deposits (40-150m) which generally consist of rapidly alternating sequences. The silt and clay, the quaternary rocks constitute various types, of alluvium (Murat, 1972; NGSA, 1978; Allen , 1965) :
i.
The coastal margins there are deposits of recent sands forming beach ridges.
ii.
Behind the sands and beach ridges are the lagoon alluvium of a mixture of sand and organic matter.
iii.
Next, porous sand with clay intercalation in constantly flooded
iv.
The relative higher grounds in the northern half of the study area is made up of sands and sandstone with little shale.
Geomorphology, the Niger Delta has four geomorphologic units: The main drainage in the study area is River Niger and its tributaries. From 1km in Agbere, the River breaks into two main branches: Forcados and Nun Rivers. These then form a very dense network of north-south drainage systems. The Benin Formation is overlain by various types of quaternary alluvial deposits comprising mainly of Recent deltaic sand, silt and clay of varying thickness, and spatially distributed as shown in Figure 1 (NGSA, 1978; Allen ,1965) The Niger Delta is one of the world’s largest wetlands covering over 20,000 km2 in Southern Nigeria. The Eastern Niger Delta covers two-thirds of the Niger Delta. Around 75 percent of the area is Riverine and regularly inundated with water, the
25
Niger Delta is composed roughly of four ecological zones, namely: Coastal barrier islands; Mangroves; Freshwater swamp forests and Lowland rainforests. The high rainfall and river discharge during the rainy season combined with the low, flat terrain and poorly drained soils result in extensive flooding and erosion. A dynamic equilibrium between flooding, erosion and sediment deposition is the defining characteristic of the Niger Delta ecosystem (Aprioku and Berelueiso, 1996).
Souce: NGSA,1978 ; Allen ,1965
Figure 1. Geological map of southern Nigeria, showing the study area: Ogoniland, Niger Delta
2.2 Climate of the study area The climate of the study area is the equatorial type. Generally, the temperatures are high throughout the year. There is a wet season lasting from April to October when the southwest winds dominate. The dry season months of November to March also
26
experience rainfalls and sporadic rainstorms. Therefore, there is no month, where the mean annual rainfall is over 3600mm with the highest occurring close to the south and decreasing north to about 300mm (Ewuesie, 1998). The dominant wind direction is south, southwesterly during the wet season months and northeasterly during the dry season months. Generally, the total annual rainfall is in excess of the evaporation and evapo-transpiration. In addition, humidity is high all the year round, with recorded relative humidity varying between 65% in January and 85% in August.
Figure 2. Geological map showing the study area locations Ogoniland (Gure, Kpean, Zaakpon and Yorla).
Temperatures in tropical lowlands never drop to freezing point; they are between 20oC and 28oC. Three main factors are responsible for high angle of incidence of solar radiation, little annual change in day – length and the heat capacity of the oceans and the soil temperature range is small, about 1oC or less on tropical islands and about 5oC on the equator in continental areas (Ewuesie, 1998).
27
2.3 Soils of the study area The soils of the study area varied and complex due to the interplay of rock or geologic types, the hydromorphic nature of the soil; and rich climatic environment of excessive rainfalls, see Figure 2.0. There are five major soils groups, they are: i.
Beach ridge soils
ii.
Mangrove swamp soils
iii.
Fresh water swamp soils
iv.
Sombreiro - Warri - Deltaic plain soils
v.
Coastal plain sands.
The marine sediments are along the coastal edge of the delta and the beach area. These soils are mainly sands with low organic materials where vegetation has colonized the area. The mangrove swamp soils are found in the northern sections of the coastal sediment deposits. The soils are darkish to brown due to decay of leaf and dead plants. They are unpleasant and with offensive odour. In association with these are the relatively drier/higher grounds where hydromorphic soils develop. They are rich in organic matter in its top layers but may contain too much salt especially during the dry season (Murat, 1972).
Soil distribution morphology The structure of rocks is determined by the way the rocks lie. The rock type is determined by the origin and formation of the rocks. The study area is predominately sedimentary rocks; they are composed of mud, clay, silt and sand accumulated along the coasts and deltas or deposits of the Quaternary rocks (sandy and muddy deposits). The Niger Delta consists mainly of muddy deposits pushed out by the Niger River into a relatively tide less salt sea. A brand fan-shaped piece of land is thus built up to form the most extensive flat area along the coast, and one
28
of the best examples of a delta in the world. The creeks and water channels of the coastlands form important fishing grounds and provide highways in this marshy area where road building is almost impossible (Iloeje, 1976).
Figure 3. Nigeria Oil and Gas pipeline , Niger Delta, Pipeline density showing potential sources of oil spill sites in the Niger Delta
29
Cross Reference: NGSA, 1978) Allen , 1965
Figure 4. Soil Logs , from Nsioken Agbi Ogale, Eleme L.G.A and similar to Ogoniland, Niger Delta, Nigeria
2.3.1 Native Soil Nutrient The Niger Delta is a natural wetland. In this agro-ecology, nitrogen has been found to be the most limiting plant dynamics nutrient. (Patrick and Deluance, 1976). The efficiency of nitrogen (N) utilization in both agriculture and natural wetlands is reduced because of competition between plant up take and biochemical processes functioning in the wetland soil – plant system. In recent years, a variety of wetland ecosystems, including freshwater marshes and hardwood swamp (Fetter et al., 1978; Zoltek et al., 1979) have been investigated. Flooded soils and sediments are generally characterized by the absence of oxygen compared to well-drained soils. In a well-drained soil, there is usually enough oxygen present in the soil atmosphere to act as an electron acceptor for microbial, plant root, and animal respiration. Upon flooding, the soil oxygen status is completely changed. In most
30
swamp and some water bodies, the dissolved oxygen content of the overlying floodwater remains relatively high due to:
i.
Low density of oxygen-consuming organisms;
ii.
Photosynthetic oxygen production of algae and possibly higher plant; and
iii.
Mixing of water by wind action and convection currents (Reddy and Patrick, 1984).
iv.
The biological, chemical and physical processes involved in the loss of nitrogen from flooded soils and sediments include: mineralization of organic nitrogen; nitrification of NH4-N, NH3 volatilization and denitrification.
The agronomic and ecologic significance of the simultaneous occurrence of these processes in the removal of nitrogen from flooded soil and sediments to the atmosphere have been examined by Reddy and Patrick, 1984.Though the oxygen demand is low in the overlying floodwater, the demand is usually high in the underlying soil layer, especially in those soils with appreciable organic energy source which supports a high level of microbial activity. The redox potential at which oxygen disappears from the wetland soil system was found to be in the range of + 320 to + 340 in Mv (Turner and Patrick, 1968). Oxygen reaching the soil or sediment surface from the water column is consumed during the following biochemical processes:
i.
Heterotrophic microbial respiration in the aerobic soil layer where oxygen is used as an electron acceptor.
ii.
Chemical oxidation of reduced iron and manganese, and sulfides which diffuse from the anaerobic layers; these reduced components had previously served as electron acceptors in the respiration of facultative anaerobes.
iii.
Biological autotrophic oxidation of ammonium nitrogen; the organisms involved in the oxidation of ammonium nitrogen are strictly aerobic.
31
In a flooded mineral soil, approximately 50% of the total available oxygen is consumed in oxidizing the water-soluble ferrous iron which diffuses upwards from subsurface reduced zones (Howler and Bouldin, 1971). The total oxygen consumption in a flooded soil was attributed to the oxidation of reduced iron and manganese, followed by oxygen consumption during the oxidation of organic carbon and ammonium nitrogen (Patrick and Reddy, 1976a).
2.2.2 Soil Nutrient Type The soil of the study sites are classified as Ultisol (FAO/UNESCO, 1974). Ultisols are strongly acidic and highly leached upland soils occurring in the high rainfall region. They are coarse-textured, Kaolinitic type paleudults found in the coastal areas of the country and are derived mainly from coastal plain sands ( Udo, 1973). Some Ultisols, mainly coarse-textured plinthudults and tropudults derived from the basement complex rocks (granite, granite gnesis, micaschist and quartz-schist) are also found in a restricted area of the south-eastern part of Nigeria (Udo, 1973). Ultisols have a higher percentage of active P (about 38 %) and lower fraction of occluded P (about 21 %) than the Alfisols worth 22% of active P and 35% of occluded P. This indicates that the Nigerian Ultisols have a higher fraction of total P in the available form than the Alfisols ( Udo, 1973). In a wetland system of the Niger Delta nitrification can occur in:
i.
The water column above wet soils, lake sediments, and stream sediment and;
ii.
The surface-oxidized soil or sediment layer of the wetland systems, lake sediments or ocean muds. Several researchers have documented the evidence of nitrification in the overlying water (Curtis et al., 1975) and in the surface-oxidizing sediments (Reddy et al., 1980c). The nitrogen in flooded soils and sediments and water columns occurs in inorganic and organic forms with the organic form predominating organic. Nitrogen
32
consists of compounds from amino acids, amines, proteins and humic compounds with low nitrogen content.
Nitrogen consists of ammonium nitrogen nitrate and nitrite nitrogen. In sediments, both nitrate and nitrate nitrogen occur in trace quantities. Ammonium nitrogen is the predominant form of inorganic nitrogen in the sediments and is mainly derived through mineralization of organic nitrogen. The gaseous forms of nitrogen that occur in flood soils and sediments include ammonia (NH3), Dinitrogen (N2) and nitrous oxide (N2O) (Reddy and Patrick, 1984). Sources of Nitrogen included: i.
Precipitation on the surface of flood soils and sediments;
ii.
Nitrogen fixation in the water and the sediments;
iii.
Inputs from surface and groundwater drainage;
iv.
Nitrogen release during the decomposition of dead aquatic plant and animal community; and discharge of waste effluents. A series of biochemical and physicochemical process are involved in transforming from one form of nitrogen to another form.
Organic nitrogen is converted to ammonium nitrogen through ammonification process, while conversion of ammonium nitrogen occurs through nitrification process. The transport of nitrogen from flood systems to the atmosphere occur through: i.
NH3 volatilization ; and
ii.
Denitrification of nitrate N to N2 and N2O.
For NH3 volatilization processes to occur, ammonium Nitrogen must be formed (ammonification) in the system followed by favourable optimum soil and environmental conditions. For denitrification process to occur, ammonium nitrogen should be oxidized to nitrate N (nitrification) followed by conversion to N2 and N2O. For both nitrification and denitrification processes to function at a maximum
33
rate, soil and environmental conditions must support both processes (Reddy and Patrick, 1984).
Soil physical characteristics The native soils of Ogoniland belong to the major soil group “Ultisol”. The soils have different cropping histories managing from secondary re-growth, short fallows and exhaustively cropped soil. The Ultisols also classified as Acrisols (FAO/UNESCO, 1974) are strongly acidic and highly leashed upland native soils of the Ogoniland, occurring in the high rainfall southern region.
Plate 2. Communities in Niger Delta, Nigeria Kids playing with exposed oil pipes outside a home in Nigeria's Niger Delta region. Photo: ©Michael Fleshman All Rights Reserved. Taken from internet site December 1, 2003
34
2.33 Agriculture Land Tenure The primary activity of many communities in Ogoniland is agriculture, 66% of households in the state are engaged in agricultural. Traditionally, communities manage farmlands as common resource. Large area of land are communally cleared and burned in preparation for crop production. Allocations are made annually and the first male child has the rights of inheritance, hence the systems indicate a mixture of communal and individual ownership of land. Visitors may be allocated land for farming through village committee but such cannot be inherited. According to the national Agricultural Sample Census 1993/94, 35% of holdings on land possessed on ownership tenure, 17% on rented land (FACU, 1993).
Farming and Cropping Systems There are two major categories of farming systems: annual crop and perennial crop cultivation in a bush fallowing or land rotation – farming system. Annual planting of staple crops starts in the dry season (November–March) when floodwater must have subsided. After clearing the of land, women and children plant maize, yam, cassava or vegetables
and oil palm from both the wild environment and
plantations, see Figure 3.0. Cropping systems consist of multiple crops which are sub-divided into mixed cropping and relay inter-cropping. Both involve spatial arrangement of crops, to have the advantage of macro and micro topographical features. Crops that are usually planted include cassava, cocoyam, plantain, banana, maize, yam, rice, sugar cane, and groundnut and to a limited extent cash crops such as oil palm and rubber.
35
In addition to the staple crops, high priced vegetables such Telfaira spp., Amaranthus spp. Waterleaf, melon and sweet potato are use as cover crops. Newly cleared forests are utilized for plantain and banana to take advantage of high organic matter status. Various crop combinations of yam/melon/maize/cassava, plantain/cocoyam telfaira and maize are arranged in relay forms. Plantain may start bearing at 8 months, but it is allowed up to 4-5 years a piece while banana could stay longer, up to 7 years. Crop plants such as Citrus spp, kola, guava, mangoes, plantain, pawpaw, pear and pineapple may be planted around homesteads and as avenues along pathways or boundaries of farms (World Bank, 1992).
Shell’s oil spills blight daily life for ordinary Nigerians in the Niger Delta, Airport Road, Port Harcourt, June 2004. www.stakeholderdemocracy.org/main/
Figure 5 Ecological and forest areas of the study area -Niger Delta
The predominant method of maintaining soil fertility remains
the age shifting
cultivation and bush following systems which involve cropping the land for a
36
length of fallow periods of 1-2 years. Alternating with fallow periods of 2-10 years. Depend on the nature of the forest land, the crops grown, as well as the relative pressure on limited livestock farming such as rearing goats, sheep and poultry is practiced in various localities of the study area. Generally, three subsystems can be recognized within the traditional farming system of the study are: i.
Rudimentary homestead garden with fruit trees, plantain, limited staples and planting of vegetables around homes; near farms – staples and vegetables on small scale;
ii.
Distant farm – plantain, melons, staples on large scale.
Land degradation and flooding constitute major constraints to agriculture in the freshwater forest zones of Ogoniland. As a result, agriculture is limited to areas with sufficiently short flooding periods to allow for a complete growing season (Dabibi, 1995).
Plate 3. Fishing was once a prime activity in Ogoniland, it was evident from community feedback and field observations that it has essentially ceased in areas polluted by oil
37
Forestry There are four forest zones viz. Coastal rainforest, mangrove forest, freshwater swamp and lowland rainforest. The costal rainforest is a barrier island that vary in width from 1.0km around Akassa to about 10.0km at the south of Ramos River (543,596 ha.). The lowland rainforest that once existed on the plains of Sombreiro, Otamiri and Imo Rivers has given rise to farmlands in Ogoniland, see Figure 4.0. The extensive mangrove forest along the southern part of the state as well as the riverine forest are tree areas being exploited for firewood collection, agriculture production and routes for oil pipeline (World Bank, 1995).
2.3
Assessing Oil Spill Damage
The Ogonis are one of more than 20 ethnic groups living in the 70,000 square kilometers Niger Delta oil-producing area where Shell Petroleum Development Company (SPDC) operates. Out of a total Delta population of about six million, the Ogonis number some 500,000 people divided into 82 communities within an area of about 1,000 square kilometers. The majority of this rapidly expanding population are farmers and fishermen. Some work in the oil industry either for SPDC or contractor firms (SPDC, 1995). In general, oil spill hazards have cost the study area and the Eastern Niger Delta heavily in human and material terms for the simple reason that it has been endemic in its border. Although, failure and human error spills are decreasing, sabotage oil spills have increased causing continued damage to both the environment and the national economy (Aprioku, 1999).
In Ogoni, the first discovery was Bomu field in 1958, followed by Korokoro in 1962, and Yorla, Bodo West and Ebubu in the 1970s. In those days, Environmental Impact Assessments (EIA) has not been developed, so none were completed in the Ogoni area. In Ogoni from 1985 up to the beginning of 1993, when SPDC withdrew the staff from the area, 5,352 barrels of oil were spilled in 87 incidents (Aprioku, 1999) .Sixty of these incidence were sabotage using hacksaw.
38
Plate 4. Children view of gas flaring, Niger Delta
39
References Aprioku, I.M. (1999).Collected Response to oil spill hazards in the Eastern Niger Delta of Niger Delta of Nigeria. Journal of Environmental Planning and management 42 (3) 389-408pp. Aprioku, I.M and Bereiweriso, L.O.F (1996) .Environmental health hazards and accidents: experience from rural Rivers state Nigeria, presented at the EBAN conference, November (Ekpoma). Curtis, E.J., Durran, C.K., and Harman, M.M., (1975). Nitrification in Rivers in the Trent Basin. Water Res. 9, 255p. Dabibi L.G (1995). A paper presented by Shell Petroleum Development Company of Nigeria Limited on Sub-Theme: Entomology and Agricultural Extension Service. The SPDC (East) Experience: Operational Details. 28th November, Port Harcourt, Nigeria. Ewuesie, J.V. (1998). Elements of tropical Ecology, Heinemann Educational Books, Inc., London. Envir-Health
Consultants
(1995).
Files
on
petroleum
exploration
and
Environmental Health hazards (Pers. Comm.). Fetter, C.W., Sloey, W.E., and Spangler, F.L., (1978). Use of a natural marsh for waste water polishing. J. water pollut. Control fed., 50.290p. FAO, Soil map of the world. FAO/UNESCO Project. Key to soil units for the world map of the world. FAO, Rome 16pp. FACU (1993). Federal Agricultural Coordination (FACU), Environmental Impact Assessment of the National Fadama Development Project (Southern Sates, Nigeria),1-145pp. Howler, R.H and Bouldin, D.R. (1971). The diffusion and consumption of oxygen in submerged Soils, Soil Sci, Soc. Am. Proc., 36. 202p. I.I.T.A. (1993). The soils of IITA (International Institutes of Tropical Agriculture). Communications and Information Office IITA, PMB 5320, Ibadan, Nigeria.
40
Idoniboye-Obu, B. (1994). Compensation for ecological disturbances and personal losses, paper presented at the conference on marine pollution control, (Port Harcourt, Rivers State, University of Science and Technology) Nigeria. Idoniboye-Obu, B. (1991). Damage assessment following an oil spill in Nigeria, NNPC seminal paper, Port Harcourt, Nigeria. SPDC (1995). Shell Petroleum Development Company of Nigeria Limited (SPDC), 1991. Review of Community and Environment April, 1995. Public affairs (RICL), Freeman House, 21/22 Marina, Lagos, Nigeria. Reddy, K.R.; Patrick, W.H., Jr.; and Phillips, R.E., (1980c). Evaluation of selected processes controlling nitrogen loss in flooded Soils, Soil Sci, Soc. Am. J., 44, 1241p. Turner, F.T.; and Patrick, W.H., Jr., (1968) .Chemical changes in water logged soils as a result of oxygen depletion. Trans. 9th Int. Congr. Soil SCI. (Australia), 4, 53 p. Reddy, K.R., and Patrick, W.H., Jr., (1984).Nitrogen Transformations and loss in flooded soils and sediments critical reviews in Environmental control. Vol. 13, Issue 4, 273 - 309pp. Murat, R.C. (1972). Stratigraphy and palaegeography of creataceous and lower Tartiary of Southern Nigeria. In: Dessauvagie, T.F.J and Whiteman, A.J (EDS) 251-266pp. Patrick, W.H., Jr. and Reddy, K.R., (1976). Nitrification identification reactions in flooded sols and sediments dependence on oxygen supply and ammonium diffusion. J. Enviren, Qual., 5, 469p. Patrick, W.G., Jr. and Delume, R.D., (1976). Nitrogen and phosphorus utilization by spartina alterniforna in salt mark in Barataria Bay. Louisiana, Estuarine coastal Mar. Sci., 4,59,1976. Udo, F.O (1973). Availability of native and applied phosphorous to maize (Zea mays L) in some Nigerian soils. Ph.D Thesis, University of Ibadan, Nigeria.
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Uzakah R.P. (1996). A paper presented by Shell Petroleum Development Company of Nigeria Limited on Sub-Theme: The SPDC (East) Experience: Operational Details 28th November, Port Harcourt, Nigeria. World Bank (1992).Forestry Sector Review Report No. 10744 – UNI. World Bank (1995). Defining an environmental development strategy for the Niger Delta, Volume 1, Industry and Energy Operations Division, West Central Africa Development, 1-150pp. World Bank (1992). Forest Sector Review Report No. 10744-UNI. Zoltek, J.; Bayley, S.E.; Hermann. S.J.;Tortora. L.R., and Dolan, T.J. (1979). Removal of nutrients from treated municipal wastewater by freshwater marshes. Final Report to city of Clermont. Florida center for wetlands. University of Florida, Hainesville, USA.
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CHAPTER THREE 3.0 Materials and Methods 3.1 Research Area In Ogoniland, the first discovery of petroleum was in Bomu field in 1958, followed by Korokoro in 1962 and Yorla, Bodo West and Ebubu in the 1970s. In those days, Environmental Impact Assessments (EIAs) had not been developed, so none were completed in the Ogoni area. SPDC withdrew its entire staff from Ogoniland in January 1993 in the face of increasing intimidation and attacks from the communities (SPDC, 1995). SPDC operations are about two-thirds of the Niger Delta which covers over 20,000 km2. It is bounded by latitudes 4o20’N and 5o35’N and longitudes 5o30’E (Aprioku, 1999).
SPDC and its joint venture partners, the Nigerian National Petroleum Corporation (NNPC), Elf and Agip have five major oilfields in the area with 96 Wells looked up to five flow station in Bomu, Korokoro, Yorla, Bodo West and Ebubu. The fields all date from the 1960s and 1970s and currently have a production potential of 28,000 barrels a day, about three percent of SPDC’s crude production. So far, 634 million barrels have been extracted from the area with production peaking in 1973 at 108,000 barrels a day (SPDC, 1995). Oil revenues provide about 90 percent of
Nigeria’s foreign exchange and some 80 percent of the Federal
Government’s total revenue, part of which is for the development of oil-producing areas by providing infrastructure such as roads, electricity, water, schools and other basic amenities. One of the biggest challenges facing the degradation of the soil is oil exploration, (Aprioku, 1999), see Figure 5.0
The Environment The Niger River enters Nigeria from the northwest, crossing the western part of the country to join the Atlantic Ocean in the South. Near the coast, the River forms this delta with mangrove forests, Lagoons, and Swamps stretching about 100km (about
43
60 miles) inland. The Niger Delta is the largest in Africa, covering an area of about 36,000 sq.km ( about 14,000 sq. miles). Any industrial enterprise, including oil operations, has an impact on the environment, and this is true in Ogoniland. A further impact on the lives of people in the area comes more from the rapidly expanding population which has caused deforestation, erosion and over-farming. Leading to degraded soil.
They are unique difficulties in operating 86 flow-stations and about 6,200 kilometers of pipelines and flow-lines; and 31,000 square kilometers of the Niger Delta in a variety of extreme habitats including humid swamp forest, mangrove swamp, seasonally-flooded forest, (SPDC, 1995).From 1993 to October 1994, following the withdrawal of SPDC staff from Ogoni, there have been another 25 spills, 18 of which have been confirmed as sabotage, with another Yorla site. SPDC has been using Ogoni contractors to clean up these spills where it since the beginning of 1993, all five of flow-stations in the Ogoniland area have been vandalized (SPDC, 1995).
3.2
Soil Sampling and Analysis
The depths of the bore on the polluted sites with hydrocarbon from
pipeline
breakage are 0-15cm and 15-30cm depths on each location. The soils were air dried ground and sieved using a 1mm nylon fIbre sieved to remove rocks, roots and other large particles. Precautions were takes to avoid contamination during sampling, drying, grinding and storage. The pH water was measured (Hendershot and Lalande, 1993). Organic Carbon (Org C.) content was determined using the Walkley and Black (1934) Method. The total N in the soil was determined by the Micro-kjedahl digestion followed by distillation and titration (IITA, 1979). Available P was determined using Mehlich -3 extracts. Exchangeable cation (K+, Ca++, Mg++) was determined by Mehlich -3 extracts. K+ was determined by flame emission spectroscopy and Ca+ and Mg+ by atomic absorption spectroscopy
44
(Anderson and Ingram, 1989). Heavy metals (Cu, Zn, Mn and Fe) analysis was determined using Mehlich -3 extracts. Atomic adsorption spectrometer (AAS).
3.3
Results
All data set were subjected to statistical analysis as appropriate. Analysis of variance was conducted using the generated linear model (LLM) procedure to evaluate variance over locations, depths, macronutrients and the study areas. Mean separation was done using (SAS, 1985).Correlation and Regression
micronutrients
of
Duncan Multiple range test
analysis were also conducted.
45
References SPDC (1995). Shell Petroleum
Development Company of Nigeria Limited
(SPDC), 1991 Review of community and Environmental April, 1995. Public affairs (RICL), Freeman House, 21/22 Marina, Lagos, Nigeria. Techicon Industrial Corp., Industrial Method No.447 – 77A. Tarry Town, New York. Techicon Industrial Corp., Industrial Method No.116 – D071 – 01. Tarry Town, New York, USA. De Saussure N.T (1804). Recherches Chimiques sur la Vegetation Nyon Paris. In Soil Testing and Plant Analysis revised edition Walsh LM and beaton J D (ed) (1963). Soil Sci SOC Amer Inc Madison Wisconsin, USA. FAO (1974). Soil map of the world, FAO/UNESCO project, Key to soil units for the world, map of the world, FAO, Rome 16pp. Iloeje, N. P (1976). A new Geography of Nigeria, Longman Nigeria Limited, Ibadan, 26-33pp. Macy P. (1936). The quantitative mineral nutrient requirement of plants. Plant Physiol 11, 749-764. Tyner,E.H (1947). The relationship of corn yield to leaf nitrogen phosphorus and potassium content Soil Sci Soc. Am Proc 11, 317-323. Ulrich, A (1943).Plant analysis a diagnostic procedure. Soil Sci 55, 101-112. Ulrich, A (1949).Critical nitrate levels of Sugar beets estimated from analysis of petiole and blades with special reference to yields and sucrose concentrations. Soil Sci 69, 291-309. Ulrich, A and Hills F. J (1967). Principles and Practices of plant Analysis 11-24. In soil Testing and Plant Analysis Part 11, SSS . A Special Publ series No 2, Soil Sci Soc Amer Madison Wis, USA.
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CHAPTER FOUR 4.0 Results and Discussion The effects of hydrocarbon pollution on the soils and its chemical properties. The results of the Soils analysis showing macro nutrients and micro nutrients of the natives (unpolluted) and impacted (polluted) soils of the study area as shown in Table 1.
Chemical Properties The Principle by which nutrient concentration in plants is related to crop yield perhaps was ushered in by earlier work done on plant analysis De Saussure (1804). Since then, useful relationships have been developed among or between growth rate and/or yield and nutrient supply and concentration in crops. One type of relationship involves crop yield, nutrient concentration and nutrient supply from the soil or soil plus added nutrients.
One useful concept widely used to relate the soil nutrient, plant nutrient and crop yield in crop production called Critical plant nutrient concentration level or optimum concentration. It has been defined in various ways: As the narrow range of concentration at which growth or yield begins to decline in comparison to plants at a higher nutrient level (Ultrich, 1949). As the concentration which is just adequate for maximum growth (Tyner, 1947); and as the concentration above which sufficiency occurs (Jones, 1970).
These techniques were used for a number of crops and found useful (Ulrich, 1949; Ulrich and Hills, 1967). The critical levels of nutrients were largely independent of the level of other factors (Macy, 1936). However, observed from the study area, the critical levels will be influenced by several factors including the impacted effects of hydrocarbon on the native soil nutrients.
47
4.1 Native Soil Nutrients The agricultural systems in the humid tropics are being faced with rapid nutrient depletion because of the low chemical buffering capacity of the low activity clay soils (Kang and Wilson, 1987; lsichei and Maoghalu, 1992). Leaching processes are at their peak in humid tropical regions, where a predominance of clay minerals such as kaolin, gibbsite, haematite, and goethite can be observed. Local conditions particularly the enrichment of fresh rock that can occur at active plant boundaries (Fyte et al., 1983), often determine the composition of the clay mineral fraction of soils irrespective of the particular climatic zone in which they occur. The distribution of organic matter in the tropical soil decreases with increasing depth. More decomposition occurs in the upper layers as more organic matter is added in these and aeration is more adequate than below (Agboola et al., 1985).
Jones (1973) found that the equilibrium organic matter content in Nigeria soils (015cm) under an established fallow of the order of 1.03 percent from an initial value of up to 2 percent, most of the decline occurring in the first year of cropping. The frequency and timing of the burn have dramatic effects on the vegetation. Frequent burn encourages grasses over tree vegetation, late burn encourages perennial grasses, and annual grasses are encouraged by early burn (Afolayan, 1978; Alfoleyan and Ajayi, 1979; Charreau, 1974). To emphasize the low levels of fertility of residual soils of the humid tropical Egbeda, Lagos (South-western Nigeria) the organic carbon % of the depth (0-16)cm is 1.37 and 10-36cm is 0.41- 0.50 cm (Moormann et al., 1981) .
Increased availability in the soil may also be caused by mineralization of organic P in the depth of soil affected by heat since, in the Nigerian soils in any event, Enwezor and Moore (1966) found organic P to be more than 40 percent of the total P. The generally low total P in these soils may be attributed to the low content in
48
the parent materials from which these soils have been formed (Uzu, et al., 1975; Ibedu, 1982). The distribution along the profile depth varies from soil to soil. There appears to be no studies though on how the accumulation is affected by the decrease in organic matter which results from successive cropping after a fallow, Greenland (1958) concluded that the extent to which NO3-N accumulates is related to the nutrifiable N in the soil which has to be a function of the amount and nature of the organic matter particularly the C to N ratio .The NO3-N which accumulated at the commencement of the wet season appears to be lost mainly by leaching (Handy, 1946; Griffith, 1951), and to a lesser extent by denitrafication (Greenland, 1958).
4.2
Impacted Soil Nutrient
4.2.1 Soils chemical properties and hydrocarbon pollution Macronutrients In the impacted study area as shown in the Table 1. The pH 4.30 - 5.20 at P< 0.01 (LSD 0.38); Nitrogen oxide (No) 0.095 - 0.74 gkg-1 at P < 0.10 (LSD 0.62; Potassium (K) 0.065 - 1.37 cmol kg-1 at P
