MICROBIOLOGICAL AND PHYSICOCHEMICAL ASSESSMENTS OF DIESEL CONTAMINATED SOIL.

ABSTRACT

Microbiological and physicochemical assessments of diesel contaminated soil were done. Four soil samples were collected from diesel engine generator sites. One sample was collected from diesel oil free environment. The soil samples were analyzed for total heterotrophic bacteria (THB), total heterotrophic fungi (THF), hydrocarbon utilizing bacteria (HUB) and hydrocarbon utilizing fungi (HUF). The result showed that total heterotrophic bacterial count ranged from 1.52 x 107-2.63x107 cfu/g while total heterotrophic fungal count ranged from 3.0x106 -7.4x106cfu/g. The hydrocarbon utilizing bacteria was in the range of 5.6x105-1.66x106 cfu/g while hydrocarbon utilizing fungi ranged from 1.5x105 -5.3x105cfu/g. The bacteria isolated were Bacillus sp., Micrococcus sp., Pseudomonas sp., Staphlococcus sp., Streptococcus sp., Corynebacterium sp., Flavobacterium sp., Arthrobacter sp., Acinetobacter sp., Klebsiella sp., and Alicagenes sp. Micrococcus sp., Pseudomonas sp., and Bacillus sp., showed heavy growths as all the organisms grow in the diesel media at different rates. The fungi isolated were Aspergillus sp.,Fusarium sp., Geotricum sp., Rhizopus sp., and Cladosporium sp. Aspergillus sp. Showed the highest occurrence of growth among the fungi isolated. The following physicochemical properties of pH, conductivity, Ca2+, Mg2+, oil and grease, PO4, SO4, NO3, TPH and BTEX were done during the course of this study. Diesel pollution increased the concentrations of NO3, SO4, TPH, Ca2+ and Mg2+ of the contaminated soil. There were no significant differences in the BTEX concentrations, conductivity and pH of the samples analyzed. The result showed that the pollution of soil with diesel oil causes great effects on soil physicochemical characteristics and thus affects microbial nature and population of such soil.   

TABLE OF CONTENTS

Title Page ﾿ i

Certification ﾿ ii

Dedication ﾿         ﾿ iii

Acknowledgment ﾿ iv

Table of contents ﾿ v

List of tables ﾿ ix

List of figures                                                                                    x

Abstract ﾿ xi

CHAPTER ONE

1.0 ﾿ Introduction ﾿ 1

1.1 ﾿ Aims and objectives    ﾿ 2

CHAPTER TWO

2.0 ﾿ LITERATURE REVIEW

2.1 ﾿ Biology of soil ﾿ 3

2.2 ﾿ Soil profile ﾿ 4

2.2.1 ﾿ Structure of Soil Profile ﾿ 5 ﾿  

2.3       Soil Structure ﾿ 6

2.4 ﾿ Chemical properties of soil ﾿ 7

2.4.1    Cation exchange ﾿ 10

2.4.2. ﾿ Soil pH ﾿   ﾿ 8

2.4.3. ﾿ Heavy metals ﾿ 9

2.5 ﾿ Soil microbial community ﾿ 9

2.6 ﾿ Components of soil microbiota ﾿ 10

2.7 ﾿ Diesel ﾿ 11

2.8 ﾿ Chemical properties of diesel soil ﾿ 11

2.9 ﾿ Major sources of diesel contamination of soil ﾿ 12

2.10 ﾿ Diesel Degradation by Microbes ﾿ 12

2.11 ﾿ Health and Environmental Risks Regarding contamination of soil by

﾿ Diesel fuel ﾿ 13

2.12 ﾿ Bioremediation ﾿ 14

2.13 ﾿ Advantages of bioremediation ﾿ 15

2.14 ﾿ Disadvantages ﾿ of bioremediation ﾿ 16

CHAPTER THREE

3.0 ﾿ MATERIALS AND METHOD

3.1 ﾿ Study area ﾿ 17

3.2 ﾿ Sample collection ﾿ 17

3.3 ﾿ Preparation of media ﾿ 17

3.4 ﾿ Preparation of sample and isolation ﾿ 18

3.6 ﾿ Microbial characterization and Identification ﾿ 19

3.6.1 ﾿ Identification of Bacterial Isolates ﾿ 19

3.6.2 ﾿ Gram Staining ﾿ 19 ﾿

3.6.3 ﾿ Motility Test ﾿ 20

3.6.4 ﾿ Indole test ﾿ 20

3.6.5 ﾿ Catalase Test ﾿ 20

3.6.6 ﾿ Oxidase Test ﾿ 21

3.6.7 ﾿ Methyl red-Voges Proskauer Test ﾿ 21

3.6.8 ﾿ Identification of fungal Isolates ﾿ 22

CHAPTER FOUR

4.0 ﾿ RESULTS ﾿ 43

CHAPTER FIVE

5.0 ﾿ DISCUSSION, CONCLUSION AND RECOMMENDATIONS

5.1 ﾿ Discussion ﾿ 29

5.2 ﾿ Conclusion ﾿ 54

5.3 ﾿ Recommendation ﾿ 33 

Reference ﾿ 55

Appendix ﾿ 40

LIST OF TABLES

Table          Title                                                                                                   Page

 1:              Microbial count (cfu/g) ﾿ 25

 2:              Bacterial isolates and their percentage occurrence ﾿ 26

3:               Fungal isolates and their percentage occurrences ﾿ 27

4:               The value of the parameters of the contaminated and                         28

                  control soil samples ﾿

LIST OF FIGURES

Figure       Title                                                                                      page

1:              TPH Chromatograph for sample A                                             29

2:              TPH Chromatograph for sample B                                             30  

3:              TPH Chromatograph for sample C                                             31

4:              TPH Chromatograph for sample D                                             32

5:              TPH Chromatograph for sample E                                             33