Effect of Cadmium on Incubation

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