The two terms 'environmental chemistry' and 'pollution' often seem to go together, yet environmental chemistry is much more than the study of the chemical effects of pollution. In this book I have attempted to emphasise the natural mobility of the elements and their compounds. Only by understanding these normal movements can we begin to appreciate the changes - good or bad - that human activities can bring about. The breakdown of rock to form soils, the uptake of the mobi lised chemicals by plants, and the return of the dead plant material to the soil ready for further uptake has long been known as a 'biogeochemical' cycle (indicating the interaction of biology, geology and chemistry). The biogeochemical cycle is only one part of the general geochemical cycle in which material is moved from the land to the sea, possibly having entered the atmosphere, and then being reincorporated in the land mass. The elements move through their cycles in fits and starts, with many variations in chemical form occurring along the way. Environmental chemistry attempts to explain why a specific change occurs and why a par ticular pathway has been followed: of necessity, there is overlap with biology, geology and physics. One possible definition of envi ronmental chemistry is the study of the rOle of chemical elements in the synthesis and decomposition of natural materials of all kinds, including the changes specifically brought about by human actions. The selection of topics for inclusion in this book proved difficult.
Table of ContentsA The oxygen-rich planet.- 1 History of the Earth.- 1.1 Development of life.- 1.2 Distribution of the elements.- 1.3 Geochemical cycles.- 2 Oxygen.- 2.1 Chemical-compound formation.- 2.2 Molecular oxygen in the atmosphere.- B Major elements found in living matter.- 3 Hydrogen.- 3.1 Isotopes of hydrogen.- 3.2 Water.- 4 Carbon.- 4.1 The carbon cycle.- 4.2 Aqueous systems.- 4.3 Photosynthesis and the formation of carbon compounds.- 4.4 Energy.- 4.5 Geochemical accumulation of solar energy.- 5 Nitrogen.- 5.1 Natural transformation processes in the nitrogen cycle.- 5.2 Nitrogen oxides in the atmosphere.- 5.3 Nitrogen fertilisers.- 5.4 Nitrate in water supplies.- 5.5 Balanced diet and food production.- 6 Sulphur.- 6.1 The sulphur cycle.- 6.2 The sulphur-dioxide problem.- C Major elements in the Earth’s crust.- 7 Silicon.- 7.1 Silicate minerals.- 7.2 Weathering.- 8 Iron.- 8.1 Iron in natural systems.- 8.2 Iron in industrial systems.- 8.3 Corrosion.- 9 Aluminium.- 9.1 Aluminium in industrial systems.- 9.2 Aluminium in solution.- 10 Calcium and magnesium.- 10.1 Formation of calcareous rocks.- 10.2 Water hardness.- 10.3 Heart disease.- 11 Sodium and potassium.- 11.1 Clay minerals.- 11.2 Potassium fertilisers.- 11.3 Fluids in organisms.- 11.4 Radioactive potassium.- D Minor elements and environmental problems.- 12 Lead.- 13 Mercury.- 14 Zinc and cadmium.- 14.1 Sewage-sludge disposal.- 14.2 Toxicity of cadmium.- 14.3 Zinc.- 15 Phosphorus.