| Popis: |
Publisher Summary During formation and diagenesis, sediments take an active part in the biogeochemical cycles of elements. It is this ongoing interaction with biogeochemical cycles that is treated in this chapter. This interaction involves many variables and complicated physical, chemical, and biological activities. Marine sediments are formed by the deposition of particles transported to the ocean by rivers and by wind. These particles come from the disintegration of rocks by weathering processes. Physical, chemical, and biological action on rocks result in three types of weathering products: detrital material from the rock and vegetation, solutes from the dissolution of minerals and organic matter, and new minerals from chemical reactions between solutes and minerals. The reducing and oxidizing conditions in sediment determine the chemical stability of the solid compounds and the direction of the spontaneous reactions. The redox state can be recognized as a voltage potential measured with a platinum electrode. Most of the nitrogen (>90%) contributing to oceanic sediments comes from organic compounds. Nitrate and nitrite contribute only a minor portion of the nitrogen. |
