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TitreNatural sources of metals to the environment
AuteurGarrett, R G
SourceHuman and Ecological Risk Assessment vol. 6, no. 6, 2000 p. 945-963,
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 2000162
ÉditeurInforma UK Limited
Documentpublication en série
Mediapapier; en ligne; numérique
Sujetsmétaux; biogéochimie; levés biochimiques; effets sur l'environnement; etudes de l'environnement; géochimie des métaux de base; géochimie des métaux lourds; érosion; géochimie des fluides géothermiques; expansion océanique; géochimie des eaux lacustres; géochimie de l'eau de mer; géochimie des roches totales; géochimie de l'eau; géochimie atmosphérique; volcanisme; géologie de l'environnement; géochimie; minéraux métalliques
Illustrationsgraphs; tables
Résumé(disponible en anglais seulement)
Almost all metals present in the environment have been biogeochemically cycled since the formation of the Earth. Human activity has introduced additional processes that have increased the rate of redistribution of metals between environmental compartments, particularly since the industrial revolution. However, over most of the Earth's land surface the primary control on the distribution of metals is the geochemistry of the underlying and local rocks except in all but the worst cases of industrial contamination and some particular geological situations. Fundamental links between chemistry and mineralogy lead to characteristic geochemical signatures for different rock types. As rocks erode and weather to form soils and sediments, chemistry and mineralogy again influence how much metal remains close to the source, how much is translocated greater distances, and how much is transported in solutions that replenish ground and surface water supplies. In addition, direct processes such as the escape of gases and fluids along major fractures in the Earth's crust, and volcanic related activity, locally can provide significant sources of metals to surface environments, including the atmosphere and sea floor. As a result of these processes the Earth's surface is geochemically inhomogeneous. Regional scale processes lead to large areas with enhanced or depressed metal levels that can cause biological effects due to either toxicity or deficiency if the metals are, or are not, transformed to bioavailable chemical species.