An Introduction to Environmental Chemistry

ratio is therefore 4 : 11, giving a general formula Si 4 O 11. The amphibole group of minerals has double-chain structure—for ex ...

Chemical weathering is caused by water—particularly acidic water—and gases, for example oxygen, which attack minerals. However, ...

78 Chapter Four Box 4.3 Oxidation and reduction (redox) Oxidation and reduction (redox) reactions are driven by electron transfe ...

eqn. 4.5 The products are silicic acid (H 4 SiO 4 ; see below) and colloidal hydrated iron oxide (Fe(OH) 3 ), a weak alkali, whi ...

80 Chapter Four Box 4.4 Metastability, reaction kinetics, activation energy and catalysts Some reduced compounds appear to be st ...

The Chemistry of Continental Solids 81 Box 4.5 Dissociation Dissociation and dissociation constants (Kdand Ka) Many chemical com ...

82 Chapter Four Dissociation and pH As dissociation is an equilibrium process it is logical that where parameters influence equi ...

where R denotes aliphatic or aromatic hydrocarbon groups (see Section 2.7). The acidity generated by organic matter decompositio ...

The combined effects of dissolving CO 2 into soilwater (eqn. 4.7), the subse- quent dissociation of H 2 CO 3 (eqn. 4.8) and the ...

of place) or damage (broken bonds). Areas of excess negative charge are prefer- entially attacked by soil acids, resulting in th ...

tetrahedral framework is particularly weak where aluminium has substituted for silicon, since the aluminium–oxygen bond has more ...

4.5 Clay minerals The reactions to illustrate weathering of complex silicates during acid hydroly- sis (eqns. 4.13 & 4.14) p ...

maintain electrical neutrality and the sheet is classified as dioctahedral (Table 4.5). Where divalent cations fill octahedral s ...

mica group, which includes the common mica minerals and illite, the smectite group and the chlorite group. Illite is a term used ...

90 Chapter Four OH OH OH OH 1.2 nm 6 O Hydrogen bonding 6 [OH] 4 AI 4 O + 2[OH] 4 Si 6 O OH OH OH OH Fig. 4.9The structure of a ...

The Chemistry of Continental Solids 91 Box 4.6 Isomorphous substitution Isomorphism describes substances which have very similar ...

2 : 1 unit presents only basal tetrahedral oxygens on its outer surfaces. Moreover, the ionic bonding between K+in the interlaye ...

4.6 Formation of soils So far we have discussed the mechanismsand solid productsof chemical weathering without precise considera ...

The key factors in equation 4.16 are summarized in Fig. 4.13 where the soil is depicted as a simple box. Various inputs and outp ...

The Chemistry of Continental Solids 95 ClimateTemperaturePrecipitationWind Atmosphericgases Influences Vegetation* Biomassdevelo ...