OCCURRENCE OF THE RARE EARTH ELEMENTS IN COAL DERIVED HUMIC SUBSTANCES

摘要

Humic acids are ubiquitously occurring in the bio/geosphere(Stevenson 1994).Due to their polyfunctionality they can interact with metals and can fixate them in soils and sediments in a permanent manner via complexation(Tipping 2002).On coal samples high amounts of HA-heavy metal species were found(Cezikova 2001).There,the amount of humic substances depends on provenance and weathering of the coal(Martinez 1995).Aside other heavy metals also rare earth elements(REE)are bound on humic substances.Rare earth elements are widely utilized as tracers of geochemical and geological processes(Bechtel 2001).So total amounts of REE are used to indicate variations in redox conditions.Focus of this work is to evaluate the REE loads of humic substances and to obtain information on typical REE patterns useful for paleo-environmental investigations.