Coupling Sorption to Soil Weathering During Reactive Transport: Impacts of Mineral Transformation and Sorbent Aging on Contaminant Speciation and Mobility

Chorover, J. ; Mueller, K. T. ; O'Day, P. A. ; Serne, R. J. ; Steefel, C. I.

关键词: ADSORPTION;    AGING;    CLAYS;    CRYSTAL GROWTH;    DESORPTION;    SEDIMENTS;    SILICATES;    SOILS;    SORPTION;    TRANSFORMATIONS;    TRANSPORT;    WEATHERING;    ZEOLITES vadose zone;    contaminant sorption;    cesium-137;    strontium-90;    iodine-129;   

DOI  :  10.2172/1000980
RP-ID  :  DOE/ER/64190-3 Final Report
PID  :  OSTI ID: 1000980
Others  :  TRN: US201107%%676

美国|英语

来源: SciTech Connect

【 摘 要 】

This project aimed for a predictive-mechanistic understanding of the coupling between mineral weathering and contaminant (Cs, Sr, I) transport/fate in caustic waste-impacted sediments. Based on our prior studies of model clay mineral systems, we postulated that contaminant uptake to Hanford sediments would reflect concurrent adsorption and co-precipitation effects. Our specific objectives were: (1) to assess the molecular-scale mechanisms responsible for time-dependent sequestration of contaminants (Cs, Sr and I) during penetration of waste-induced weathering fronts; (2) to determine the rate and extent of contaminant release from the sorbed state; (3) to develop a reactive transport model based on molecular mechanisms and macroscopic flow experiments [(1) and (2)] that simulates adsorption, aging, and desorption dynamics. Progress toward achieving each of these objectives is discussed below. We observed unique molecular mechanisms for sequestration of Sr, Cs and I during native silicate weathering in caustic waste. Product solids, which included poorly crystalline aluminosilicates and well-crystallized zeolites and feldspathoids, accumulate contaminant species during crystal growth.