TABLE OF CONTENTS
Title Page
Certification
Acknowledgment
Abstract
Table of Content
List of Figures
List of Tables
List of Abbreviations
CHAPTER ONE: INTRODUCTION
1.1. Introduction
1.2. Physical and Chemical Characteristics of PAHs
1.3. Sources and Emission of PAHs
1.3.1. Stationary Sources
1.3.1.1. Domestic Sources
1.3.1.2. Industrial Sources
1.3.2. Mobile Sources
1.3.3. Agricultural Sources
1.3.4. Natural Sources
1.3.5 Uses of PAHs
1.4. Routes of Exposure for PAHs
1.4.1 Air
1.4.2 Water
1.4.3 Soil
1.4.4. Foodstuffs
1.4.5. Other Sources of Exposure
1.5. Individuals at Risk of Exposure
1.6. Standards and Regulation for PAH Exposure
1.7. Metabolism of PAHs
1.7.1. Fate of PAHs in Soil and Groundwater Environment
1.7.2. Fate of PAHs in Air and their Ecotoxicological consequences
1.8 Human Health Effects
1.8.1 Acute or Short-Term Health Effects
1.8.2. Chronic or Long-Term Health Effects
1.8.3 Carcinogenicity
1.8.4. Teratogenicity
1.8.5. Genotoxicity
1.8.6. Immunotoxicity
1.8.7. effect of PAHs Pathogenic Change
1.9. Fish
1.9.1. Food Smoking
1.10. Rationale of Study
1.11. Aims and Objectives
CHAPTER TWO: MATERIALS AND METHODS
2.0 Material and methods
2.1. Materials
2.1.1. Apparatus and Equipment
2.1.2. Chemicals
2.1.3. Fish Samples
2.1.4. Study Site
2.2. Methods
2.2.1. Collection of Fish Samples and Drying
2.2.2. Sample Preparation for the Analysis of Dried Fishes
2.2.3. Preparation of Florisil for clean-up
2.2.4. Instrument Analysis
CHAPTER THREE: RESULTS
Result
CHAPTER FOUR
4.0. Discussion
Conclusion
Reference
Appendices
ABSTRACT
Preservation of fish by drying over
different types of heat regimes have been known. However, there has not been a
comprehensive comparison in terms of the possible contamination associated with
these drying regimes. This work was set to evaluate the levels of PAHs that are
likely to accumulate in the bodies of fresh water fishes dried under heat from
charcoal, sun (sun drying), electric oven and polythene augmented drying
regimes (burning of used cellophone materials). The levels of sixteen PAHs were
determined in fish samples harvested from Otuocha River in Anambra State,
Nigeria. The fish samples were dried, pulverized and subjected to soxhlet
extraction using n-hexane at 600c for 8hrs. The water content of the
eluants were further removed with florisil clean-up before Gas chromatographic
– mass spectrometric analysis. Results obtained showed that sun-dried fish had
PAHs concentration to be 35.7+ 0.2µg/g; oven dried gave 47.7+
0.2µg/g and charcoal dried 79.53+ 0.2µg/g, while drying with firewood
resulted in 188.1+ 0.2µg/g. Charcoal drying augmented with polythene
resulted into PAHs level of 166.2+ 0.1µg/g while fish dried under heat
generated from burning firewood and polythene material resulted into PAHs
concentration of 696.3+0.2µg/g. Preliminary analysis of the fresh water
samples and the undried fish samples (control) revealed that the fresh water
contained total PAHs level of 2.86+ 0.1µg/ml, while the fresh fish 4.97+
0.2µg/g. The concentration of PAHs in all the dried fish under different drying
agents were significantly higher than the control. The result is more worrisome
in that even the fishes dried under the sun have PAHs significantly higher than
that of the control (p<0.05). It is apparent that the increase in PAHs must
have come from the environmental PAHs (exposure) under which the fishes were
dried (under sun). For the other drying regimes, in which the levels of PAHs
were significantly higher than that of sun-dried, it can be concluded that the
excessive PAHs in the body of the dried fish were from the “burning” or drying
agents. More significantly are the observed very high increase in PAHs when
drying was augmented with polythene, an agent known to be a high source of PAHs
when incinerated. Consumers of dried fish should therefore beware of the dried
fish they purchase from the local market.
CHAPTER ONE
1.1 INTRODUCTION
Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds consisting of two or more fused benzene rings (linear, cluster or angular arrangement), or compounds made up of carbon and hydrogen atoms grouped into rings containing five or six carbon atoms. They are called “PAH derivatives” when an alkyl or other radical is introduced to the ring, and heterocyclic aromatic compounds (HACs) when one carbon atom in a ring is replaced by a nitrogen, oxygen or sulphur atoms. PAHs originate mainly from anthropogenic processes particularly from incomplete combustion of organic fuels. PAHs are distributed widely in the atmosphere. Natural processes, such as volcanic eruptions and forest fires, also contribute to an ambient existence of PAHs (Suchanova et al., 2008). PAHs can be present in both particulate and gaseous phases, depending on their volatility. Low molecular weight PAHs (LMW PAHs) that have two or three aromatic rings (molecular weight from 152 to 178g/mol) are emitted in the gaseous phase, while high molecular weight PAHs (HMW PAHs), molecular weight ranging from 228 to 278g/mol, with five or more rings, are emitted in the particulate phase, (ATSDR, 1995) . In the atmosphere, PAHs can undergo photo-degradation and react with other pollutants, such as sulfur dioxide, nitrogen oxides, and ozone. Due to widespread sources and persistent characteristics, PAHs disperse through atmospheric transport and exist almost everywhere. There are hundreds of PAH compounds in the environment but in practice PAH analysis is restricted to the determination of six (6) to sixteen (16) compounds. Human beings are exposed to PAH mixtures in gaseous or particulate phases in ambient air. Long term exposure to high concentration of PAHs is associated with adverse health problems. Since some...
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