DETERMINATION OF THE LEVELS OF POLYCYCLIC AROMATICHYDROCARBONS (PAHs) AND HEAVY METALS IN SOILS AND PLANT FOODCULTIVARS FROM SOME OIL EXPLORATION COMMUNITIES OF BAYELSASTATE.

ABSTRACTSoils and vegetation in three selected communities in Bayelsa state wereinvestigated for presence of recalcitrant Polycyclic aromatic hydrocarbons(PAHs) and heavy metals in the soils and edible plant food cultivars. Two of thecommunities, Angiama and Oporoma are crude oil impacted areas having hadoil spillage accidents in 2010 and 2008 respectively while Yenagoa a non crudeoil impacted area is used as control. Physicochemical properties of soils fromthese study areas were investigated using standard methods, the polycyclicaromatic hydrocarbon (PAHs) in the soil and food cultivars were determinedusing Gas Chromatography - Mass Spectrophotometer while heavy metals wereanalysed by Atomic Absorption Spectrophotometer. The result of theinvestigation reveal that oil spillage degrades the soil as revealed by thesignificant reduction in pH , moisture content and bulk density of soils fromAngiama and Oporoma communities compared with Yenagoa. Soil fromAngiama had the highest percentage (%) organic carbon (4.40±0.53%) and totalhydrocarbon (846.40±10.11mg/kg) followed by Oporoma (2.13±0.12% and520.00±5.00mg/kg respectively) and Yenagoa (1.30±1.08% and62.20±0.26mg/kg respectively). The anion levels of soil nitrate (NO3

2-) andphosphate (PO4

3-) were significantly highest in soil residues from Yenagoa thanin Angiama and Oporoma while the levels of exchangeable cations (Ca2+, Mg2+,K+,and Na+) were highest in Angiama than in Oporoma and Yenagoa soils. Thevalues were significantly different at p<0.05.This suggest that exchangeablecations accompany oil spill. High molecular weight recalcitrant PAHs Benzo(a)pyrene, benzo(a) anthracene, Benzo(K) fluoranthene, Benzo(b)fluoranthenewere present in both Angiama and Oporoma soil but were not detected inYenagoa. Except for phenanthrene, low molecular weight PAHs were notdetected in soil samples from Yenagoa, occurred sparingly in Oporoma butwere predominant in Angiama. Food cultivars from both Angiama andOporoma were equally proportionately contaminated with these high molecularweight PAHs. The leafy vegetables (pumpkin and scent leaf) were far morecontaminated than the tubers (yam and cassava). Heavy metal contaminants ofsoils and food cultivars mirror exactly the same trend associated withrecalcitrant PAHs. These results reveal that oil spillage activity is responsiblefor the preponderance of PAHs and heavy metals in the soils of the Niger Delta.It also demonstrates that by the process of natural weathering polluted soils are

remedied over time. Given the appreciable accumulation of these crude fractiontoxicants in food cultivars, it is suggested that the foods remain a majorendogenous source of PAHs and heavy metals among the people of the area.

TABLE OF CONTENTSTitle page iiCertification iiiApproval ivDedication vAcknowledgement viAbstract viiTable of content viiiList of tables ixList of figures xList of Abbreviations xi

Chapter One1.0 Introduction 11.1 Statement of the problem 21.2 Aims and objectives 31.3. Significant of the study 31.4. Relevance of the study 41.5. Description of the study areas with maps and pollution history 4Chapter Two2.0 Literature review 82.1 Occurrence of Polycyclic aromatic hydrocarbons (PAHs) 8

2.2 List of Polycyclic aromatic hydrocarbons (PAHs) 9

2.3 Classification of PAHs 102.4 Transport and Partitioning of PAHs 112.4.1 Vapour pressure 112.4.2 Henry’s Law 122.4.3 Solubility 122.4.4 Octanol water (Kow) and Organic Carbon (Koc) Partition Coefficient 132.5 Health hazards oh PAHs 142.5.1 Respiratory effect 142.5.2 Immunological effects 142.5.3 Reproductive effects 152.5.4 Developmental effects 152.5.5 Genotoxic effects 162.5.6 Cancinogenic effect 182.6 Pollution sources of PAHs 192.6.1 Air 202.6.2 Water 202.6.3 Soil 212.7 Heavy metal contaminants of crude oil 212.7.1 Lead ( Pb) 222.7.2 Cadmium (Cd) 242.7.3 Copper 262.7.4 Zinc (Zn) 282.7.5 Iron (fe) 30

2.7.6 Nickel (Ni) 312.8 Crude oil spills and the environment 32

2.9 Recalcitrant PAHs 342.10 Uptake of PAHs and Heavy metals by food crops 35Chapter Three3.0 Materials and Methods 383.1 Materials 383.1.1 Equipments/Apparatus 383.1.2 Chemicals and Reagents 383.2 Methods 393.2.1 Sample collections and preparation 393.2.1.1 Sample collection 393.2.1.2 Sample preparation 403.2.2 Analytical methods 413.2.2.1 Characterization of soil samples 413.2.2.2 Physicochemical analysis of soil samples 413.2.2.3 Determination of PAHs 453.2.2.4 Determination of heavy metal contaminant 473.2.2.5 Result Analysis 48Chapter Four4.0 Results 494.1 Physicochemical properties of soils from polluted areas 494..2 Residual polycyclic aromatic hydrocarbon constituents of soils from the study areas 514..3 Polycyclic aromatic hydrocarbon levels in tuber cultivars from the study areas 53

4.4 Polycyclic aromatic hydrocarbon levels in plant leaves from the study areas 564.5 The composite pattern of PAHs distribution in soils and plant food cultivars inYenagoa 59

4.6 The composite pattern of PAHs distribution in soils and plant food cultivarsin Angiama 604.7 The composite pattern of PAHs distribution in soil and plant food cultivars fromOporoma 624.8 Heavy Metal Constituents of soils from the study areas 644.9 Heavy Metal Constituents in tuber cultivars from the study areas 654.10 Heavy Metal Constituents in plant leaves from the study areas 684.11 Composite pattern of heavy metal distribution in soils and food cultivarsin Yenagoa 714.12 Composite pattern of heavy metal distribution in soils and food cultivarsin Angiama 724.13 Composite pattern of heavy metal distribution in soils and food cultivarsin Oporoma

Chapter five5.0 Discussion 665.1 Physicochemical properties of soil from the study areas 665.2 Residual Polycyclic aromatic hydrocarbon constituents of soils from thestudy areas 675.2.1 Polycyclic Aromatic hydrocarbon levels in tuber cultivars from the study areas 695.2.3 Polycyclic Aromatic hydrocarbon levels in plant leave from the study areas 705.3 Heavy metal concentration in soil from the study areas 725.3.1 Concentrations of Heavy metal in tuber cultivars from the study areas 735.3.2 Heavy metal concentration in plant leaves from the study areas 73Conclusion 78Contribution to knowledge 78References 79Appendices

CHAPTER ONE1.0 INTRODUCTIONCrude Oil has had profound impact on the world civilization than any single natural resource

in recorded history. Oil has become a very decisive element in defining the politics, rhetoricand diplomacy of states. All over the world, the lives of people are affected and destiny ofnations has been determined by the result of oil explorations. Oil keeps the factories of theindustrialized countries working and provides the revenue, which enables oil exporters toexecute ambitious national and economic development plans. The march of progress wouldbe retarded and life itself would be unbearable if the world is deprived of oil that is why oilhas become the concern of government, a vital ingredient of their politics and a crucial factorin the political and diplomatic strategies (Pyagbara, 2007).Nigeria joined the league of oil producing nations on August 3rd, 1956 when oil wasdiscovered in commercial quantities at Oloibiri in Bayelsa and today ranks as the leading oiland gas producer in Africa and the 6th largest oil exporter in the world (Pyagbara, 2007). Asoil was struck in commercial quantities in Nigeria, it also signaled the beginning of aprofound transformation of Nigeria’s political and economic landscape. Since the 1970s, oil

has accounted for 80% of the Nigerian government’s revenue and 95% of the country’sexport earnings. Interestingly almost all of Nigeria’s oil and gas resources come from itsNiger delta region occupied by mosaic of indigenous nationalities. Crude oil is made ofdifferent fractions and when there is spill on the environment, spreading immediately takesplace, the gaseous and liquid components evaporate, some get dissolved in water and evenoxidized and yet some undergo bacterial changes and eventually sink to the bottom bygravitational action (Akpofure et al., 2000). Mangrove forests have fallen to the toxicity ofoil spills, the rainforest has fallen to the axe of oil companies, wild life and game have beendriven away and farmlands have been rendered infertile with gross implication on the right to adequate food (Pyagbara, 2007; Omofonmwam and Odia, 2009). During oil spills theprocess of photosynthesis which enhances plant diversity is impaired since the process isreduced because spilled crude have a high absorbance property of UV light which makesplant leaves not to photosynthesis and thus die leading to biodiversity loss (Nwilo andOlusegun, 2007).

The toxic crude affects not only the herbs and shrubs but also the soil fauna. Thevolatile lower molecular weight components of the crude affects aerial life, while thedissolution of the less volatile components which makes water toxic affects aquatic life(Akpofure et, al., 2000). Gaseous and particle-bound polycyclic aromatic hydrocarbons(PAHs) are transported over long distances before deposition and may accumulate invegetation (Tuteja et al, 2011). Heavy metal contaminants of crude oil contaminate the soiland water and thus enter the food chain. In this manner humans are indirectly exposed toPAHs and heavy metals through the food chain.

1.1 Statement of the problemThe most profound and adverse impact of oil pollution in Niger Delta is environmentalpollution with far reaching implications on all other aspects of traditional lifestyles andlivelihood of the people among which is the total loss of biodiversity and destruction ofhabitats largely due to soil degradation and persistence of recalcitrant hydrocarbonconstituents in water bodies, soil and food cultivars.

1.2 Aim and Objectives of the studyNigerian crude oil contains gaseous and particle-bound polycyclic aromatic hydrocarbons aswell as some heavy metals that pollute drinking water and marine organisms. These toxicantsmay be passed up the food chain and become a major source of human exposure.

1.2.1 Aim of the studyThe aim of this study is to determine those recalcitrant polycyclic aromatic hydrocarbonfractions preponderant in soils following episodic oil spillage events as well as theaccompanying heavy metal pollutants and how they impact on food cultivars.

1.2.2 The Objectives are:1)To ascertain the different recalcitrant polycyclic aromatic hydrocarbons that predominatein soils following episodic oil spillage events2 ) To establish to what extent those recalcitrant PAHs are taken up by food cultivars whichas primary producers introduce them into the food chain3) To determine the heavy metal pollutants accompanying these episodic oil spillage events

in the soil and how they join the food chain through uptake by crops.4) To determine if there are any correlation in the preponderance of PAHs, heavy metals andb/w PAHs and heavy metals.