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Supply rates of natural U‐Th series radionuclides from aquifer solids into groundwater
Author(s) -
Hussain N.
Publication year - 1995
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/95gl01006
Subject(s) - groundwater , zircon , monazite , aquifer , nitric acid , leachate , nuclide , radionuclide , geology , aqueous solution , environmental chemistry , mineralogy , environmental science , chemistry , geochemistry , physics , inorganic chemistry , geotechnical engineering , quantum mechanics
Supply rates of 224 Ra and 212 Pb from zircon and monazite grains to the aqueous phase are experimentally determined by dispersing these minerals in 1N nitric acid and PRL (Physical Research Laboratory) groundwater. In nitric acid medium, recoiled 224 Ra and 212 Pb behave conservatively and are not removed by solid surfaces. However, in groundwater, 212 Pb is removed from the aqueous phase. A model relating the actual supply ratio of 212 Pb/ 224 Ra, the measured activities of 224 Ra and 212 Pb in the leachates at different times of contact and the first order removal rate constant of 212 Pb is developed. At steady state, the supply ratio of 212 Pb/ 224 Ra in nitric acid from zircon and in groundwater from monazite is evaluated to be a unique value 2.3±0.3 which agrees with the model predicted value of 2.67 based on alpha recoil supply of the nuclides and their precursors. The residence time of 212 Pb in groundwater, with respect to its first order removal, is estimated to be of the order of 39 minutes.