Heavy Metals Content In Soils In The Vicinity of Refuse Dumpsites In Calabar South, LGA



ABSTRACT

This study was done to evaluate the risk of heavy metals pollution of soils within the vicinities of refuse dumpsites in Calabar south, LGA. Soil samples were collected from a depth of 0-20cm with the use of a soil auger from ten (10) dumpsites using the stratified sampling method.  The samples were well labelled in polythene bags and transported to the laboratory where it was air-dried and subjected to physico-chemical analysis. Heavy  metals such as lead (Pb), cadmium (Cd), chromium (Cr), mercury (Hg) and nickel (Ni) were analytically determined by using the atomic absorption spectrophotometer and a statistical analysis was carried out with the use of SPSS and Microsoft excel 2007. The mean concentration of nickel (Ni) ranged between 0.93-1.64, the mean concentration of chromium (Cr) ranged between  0.18-0.36, the mean concentration of cadmium (Cd) ranged between 0.05-0.52, the mean concentration of lead (Pb) ranged between 0.01-0.03 and the mean concentration of mercury remained constant at ( Cr > Cd > Pb > Hg. The dumpsites encourage the accumulation of heavy metal in soils because of the various components of refuse generated in the society. Based on the study, the following recommendations are made; containers/waste bins should be kept at different sites/areas for dumping of wastes of different categories  instead of dumping the waste on the soil which later causes pollution, soil & groundwater monitoring programs should be initiated, establish guidelines for reclamation of areas contaminated by heavy metals, liming should be carried out on affected soils.

TABLE OF CONTENTS

TITLE PAGE                                                                                                             i

CERTIFICATION                                                                                                     ii

DEDICATION                                                                                                           iii

ACKNOWLEDGEMENT                                                                                         iv

ABSTRACT                                                                                                               v

TABLE OF CONTENTS

CHAPTER ONE: INTRODUCTION

1.1 Justification of the Study                                                                                     1

1.2 Aim and Objectives of the Study                                                                         2

CHAPTER TWO: LITERATURE REVIEW

2.1 Sources/Classification of Heavy Metals                                                               3

2.1.1 Sources of Lead                                                                                                 3

2.1.2 Sources of Mercury                                                                                            5

2.1.3 Sources of Cadmium                                                                                         7

2.1.4 Sources of Chromium                                                                                        9

2.1.8 Sources of Nickel                                                                                               12

2.2 Disposal Systems for Municipal Solid Waste (MSW)                                          15

2.3 Waste Management Strategies Used In Municipal Solid Waste (MSW)             16

2.3.1 Open Disposal/Open Dumps                                                                             18

2.3.2 Landfills/Sanitary Landfills                                                                               19

2.3.3 Ocean Disposal                                                                                                  20

2.3.4 Incineration Plants                                                                                             20

2.4 Accumulation/Contamination of Heavy Metals in the Environment                   21

2.5 Effects of Heavy Metals Contamination                                                              23

2.5.1 Lead Effects                                                                                                      24

2.5.2 Mercury Effects                                                                                                 26

2.5.3 Cadmium Effects                                                                                               27

2.5.4 Chromium Effects                                                                                             29

2.5.8 Nickel Effects                                                                                                    30

2.6 Preventing Contamination by Heavy Metals/Remediation                                  31

2.6.1 Immobilization Techniques                                                                                34

2.6.2 Soil Washing                                                                                                      35

2.6.3 Phytoremediation                                                                                               37

CHAPTER THREE: MATERIALS AND METHODS

3.1 Location/Study Sites                                                                                            39

3.2 Materials                                                                                                               40

3.3 Method of Sampling                                                                                             40

3.4 Sample Preparations                                                                                              40

3.5 Chemical Analysis                                                                                                41

3.6 Statistical Analysis                                                                                                41

CHAPTER FOUR: RESULTS AND DISCUSSION

4.1 Results                                                                                                                  42

4.2 Discussion                                                                                                             43

4.2.1 Lead (Pb)                                                                                                           44

4.2.2 Cadmium (Cd)                                                                                                   44

4.2.3 Chromium (Cr)                                                                                                   45

4.2.4 Nickel (Ni)                                                                                                         45

4.2.5 Mercury (Hg)                                                                                                     46

CHAPTER FIVE: CONCLUSION AND RECOMMENDATION

5.1 Conclusion                                                                                                            47

5.2 Recommendation                                                                                                  47       

REFERENCES

APPENDIX