Positive Uranium Anomalies in the Peatlands of Humid Zone: A Review

Resumo

In recent years, geologists have found peatlands extremely rich in uranium. They can be considered an example of the efficient operation of natural organic geochemical barriers in the humid zone. They also open up the possibility of determining the age of these peatlands by t he isotopic ²³⁰Th/²³⁴U method. The deposition of uranium in peat is due to the U(VI) bioreduction controlled by several geochemical factors: the composition of organic matter and soil solution, the redox potential, and the capacity of uranyl ions to make complexes with organic ligands. By the nature of uranium enrichment, peatlands can be subdivided into two groups: (a) peatlands enriched in uranium carried by soil and groundwater from peripheric sources and (b) peatlands enriched in uranium from underlying uraniferous rocks. The data on geography, genesis, and physicochemical conditions of positive uranium anomalies in peatlands of the humid zone are collected and analyzed in this review.