An Introduction to Environmental Chemistry

speeds up chemical reactions by supplying energy (Box 4.8). For most reactions a 10°C rise in temperature causes at least a doub ...

general dominance of evaporation over rainfall means that soluble salts tend to precipitate on the land surface, forming crusts ...

of material is greater on steeper slopes. Conversely, the potential for dissolution and transport of dissolved material is lower ...

microclimate too; these factors in turn affect the potential for erosion and dissolution. 4.6.4 Vegetation (v) The development o ...

100 Chapter Four Box 4.10 Biopolymers Cellulose Cellulose is the most common plant polymer forming the structural fibres of many ...

The Chemistry of Continental Solids 101 Hemicelluloses Hemicelluloses are the second most common class of plant polymer. Hemicel ...

electrons is harnessed in the production of adenosine triphosphate (ATP), the cell’s energy-storing compound. Terminal electron ...

(Table 4.7), and is therefore utilized first by aerobic organisms. Once oxygen has been used up other electron acceptors are use ...

to the atmosphere, and N and P to the hydrosphere is discussed in Sections 3.4.2 and 5.5.1 respectively. The biosphere clearly i ...

form these to clay minerals. Alteration is most likely in the interlayer areas, espe- cially at damaged crystal edges. The clay ...

106 Chapter Four Laterite Red oxisols (feralsols) (kaolinitic, Fe- and Al-rich) Dark vertisols (Smectitic, base cation-rich) Bas ...

of impenetrable siliceous-iron layers (laterite) inhibit plant growth. By contrast, the low-altitude vertisols have high fertili ...

under normal soil pH ranges (Table 4.8) has been used to formulate a chemical index of alteration (CIA); using molecular proport ...

By contrast, smectite clays develop in poorly drained sites. On the basaltic island of Hawaii, soil clay mineral type changes in ...

110 Chapter Four 100 0 2000 4500 Rainfall (mm) Percentage of soil Smectite Kaolinite Gibbsite Fig. 4.18The influence of climate ...

4.8 Ion exchange and soil pH Exchangeable ions are those that are held temporarily on materials by weak, elec- trostatic forces. ...

Under high soil pH conditions, damaged soil clays with exposed OH groups in octahedral layers may dissociate, forming a negative ...

nizable in the field. These features, particularly specific layers called ‘soil hori- zons’, are the basis for soil classificati ...

O HORIZON SURFACE LITTER: fallen leaves and organic debris Litter L F Partially decomposed litter A HORIZON TOP SOIL: organic ma ...

different conditions to those described for argillic horizons, the materials being removed and deposited are generally metal ion ...