Soil chemistry is the study of the chemical characteristics of soil. Soil chemistry is affected by mineral composition, organic matter and environmental factors. Soil - (i) The unconsolidated mineral or organic material on the immediate surface of the Earth that serves as a natural medium for the growth of land plants. (ii) The unconsolidated mineral or organic matter on the surface of the Earth that has been subjected to and shows effects of genetic and environmental factors of: climate (including water and temperature effects), and macro- and micro organisms, conditioned by relief, acting on parent material over a period of time. A product-soil differs from the material from which it is derived in many physical, chemical, biological, and morphological properties and characteristics. This definition is from Soil Taxonomy, second edition.
Key facts you should know about Soil:
Soil makes up the outermost layer of our planet and is formed from rocks and decaying plants and Animals. Soil has varying amounts of organic matter (living and dead organisms), minerals, and nutrients. • An average soil sample is 45 percent minerals, 25 percent water, 25 percent air, and five percent organic matter. Different-sized mineral particles, such as sand, silt, and clay, give soil its texture. • Topsoil is the most productive soil layer. • Ten tonnes of topsoil spread evenly over a hectare is only as thick as a one Euro coin. • Natural processes can take more than 500 years to form 2 centimeters of topsoil. • In some cases, 5 tonnes of animal life can live in one hectare of soil. • Fungi and bacteria help break down organic matter in the soil. • Earthworms digest organic matter, recycle nutrients, and make the surface soil richer. • Roots loosen the soil, allowing oxygen to penetrate. This benefits animals living in the soil. They also hold soil together and help prevent erosion. • A fully functioning soil reduces the risk of floods and protects underground water supplies by neutralizing or filtering out potential pollutants and storing as much as 3750 tonnes of water per hectare. • Scientists have found 10,000 types of soil in Europe and about 70,000 types of soil in the United States. • Soil stores 10% of the world's carbon dioxide emissions.
Environmental soil chemistry
A knowledge of environmental soil chemistry is paramount to predicting the fate of contaminants, as well as the processes by which they are initially released into the soil. Once a chemical is exposed to the soil environment myriad chemical reactions can occur that may increase or decrease contaminant toxicity. These reactions include adsorption/desorption, precipitation, polymerization, dissolution, complexation and oxidation/reduction. These reactions are often disregarded by scientists and engineers involved with environmental remediation. Understanding these processes enable us to better predict the fate and toxicity of contaminants and provide the knowledge to develop scientifically correct, and cost-effective remediation strategies.
- Anion and cation exchange capacity
- Soil pH
- Mineral formation and transformation processes
- Clay mineralogy
- Sorption and precipitation reactions in soil
- Oxidation-reduction reactions
- Chemistry of problem soils
- Sonon, L. S., M. A. Chappell and V.P. Evangelou (2000) The History of Soil Chemistry. Url accessed on 2006-04-11
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