ABSTRACT
Cadmium (Cd) is one of the most dangerous of soil pollutants because this heavy metal may easily move from soil to food plants through root absorption, and fairly large amounts can accumulate in their tissues without showing stress. The CEC increase from 175.554 to 105.331 and 95.502 respectively for decrease in concentration of cadmium metal, this is due to isomorphic substitution of the cadmium from the metal in cation exchange capacity (Ca, Mg, K and Na). Nitrogen also decreases because of the reaction from 0.142 to 0.086 and 0.056 respectively because of the reaction of cadmium with nitrogen in the form of nitrate which bring about more. It reacts with phosphorus in the form of phosphate which is brought about as a result of increase. The pH change 7.30 which is neutral on eight (8) weeks incubation it is slightly acidic, this may be due to displacement of hydrogen ion from the soil sample surface with cadmium, the hydrogen will now be in solution. The application of Cd had a significant negative effect on the size of soil microbial biomass (SMB) and enzymes activity (EA). Higher Cd concentrations decreased the SMB and EA more significantly than the lower concentrations. The soil texture and incubation time are important factors in governing the toxicity of Cd on the soil health and quality indicators. The loam and clay loam soils were more resistive than the sandy loam soil regarding Cd toxicity to Cmic, Nmic, and Pmic, dehydrogenase, phosphatase and urease activities. It stresses that such Cd-induced changes caused alteration of biological functions in soil ecosystem and consequently affect agricultural sustainability.
TABLE OF CONTENT
Title Page
Certification i
Dedication ii
Acknowledgment iii
Abstract iv
Table of Contents v
CHAPTER ONE 1
1.1. Introduction 1
CHAPTER TWO 5
2.0 Literature Review 5
2.1 Cadmium Background 5
2.2 Cadmium Behavior and Toxicity 6
2.3 Cadmium Accumulation 9
2.4 Hardness and PH 10
2.5 Cadmium and Fish Life Stage 11
2.6 Sub-Lethal Effects 12
2.7 Cadmium and Human Health 13
2.8 Sources of Exposure to Cadmium 14
2.9 Food and Drinking-Water 15
2.10 Physical Properties 16
2.11 Chemical Properties 17
2.12 Applications 19
2.13 Laboratory Uses 20
2.14 Biological Role 21
2.15 Environment 21
2.16 Safety (Cadmium Poisoning) 21
CHAPTER THREE 25
3.0 Materials and Method 25
3.1 Metal Determination 25
3.1.2 Wet digestion of sample 26
3.1.3 Determination of Cadmium by Atomic Absorption Spectrometry 26
3.2.1 Soil Analyses 26
3.2.2 Moisture 26
3.2.3 Cation Exchange Capacity (C.E.C) 27
3.2.4 Olsen-Available Phosphorus 27
3.2.5 Nitrogen 28
3.2.6 Determination of Magnesium (Mg) 28
3.2.7 Determination of Sodium (Na) 28
3.2.8 Determination of Calcium (Ca) 29
3.2.9 Determination of Potassium (P) 29
CHAPTER FOUR 30
4.0 Results and Discussion 30
4.1 Result 30
4.2 Discussion 30
CHAPTER FIVE 33
5.0 Conclusion and Recommendation 33
5.1 Conclusion 33
5.2 Recommendation 33
References 35