HR: 0800h
AN: H21E-1387    [Abstracts]
TI: Sorption and desorption of lead (Pb) and europium (Eu) on volcanic rocks at the Nevada Test Site
AU: * Zhang, L
EM: liqiong.zhang@dri.edu
AF: Geoscience Department University of Nevada Las Vegas, 4505 Maryland Pkwy, Las Vegas, NV 89154-4010
AU: * Zhang, L
EM: liqiong.zhang@dri.edu
AF: Desert Research Institute, 755 E Flamingo Road, Las Vegas, NV 89119
AU: Papelis, C
EM: Lambis.Papelis@dri.edu
AF: Water Resources Management University of Nevada Las Vegas, 4505 Maryland Pkwy, Las Vegas, NV 89154-4029
AU: Papelis, C
EM: Lambis.Papelis@dri.edu
AF: Desert Research Institute, 755 E Flamingo Road, Las Vegas, NV 89119
AU: Yu, Z
EM: zhongbo@unlv.nevada.edu
AF: Geoscience Department University of Nevada Las Vegas, 4505 Maryland Pkwy, Las Vegas, NV 89154-4010
AB: Previous research has shown that sorption/desorption reactions frequently control the concentration of solutes in the groundwater system at the Nevada Test Site (NTS). The hysteresis between the sorption and desorption processes determines the techniques of simulating radionuclide transport under field conditions. In this study, batch sorption and desorption experiments of lead (Pb) and europium (Eu) were conducted to study the partitioning of dissolved radionuclides at the groundwater-rock interface. Lead, showing the stronger binding affinity, can be used to evaluate conservatively the retardation of strongly binding radionuclides, such as plutonium. Europium can be used as the natural analog of transuranic radioactive solutes because of its similar valance and geochemical characteristics. Samples, including matrix and fracture cut from cores, were collected from the Western Pahute Mesa (WPM) at NTS. Based on the results of sorption and desorption batch experiments with Pb and Eu, adsorption envelops and fractional desorption were obtained, as a function of time. The sorption behavior of both cations was pH-dependent, with sorption uptake increasing with increasing pH. The sorption uptake of Pb was always higher, compared to Eu, for the same pH value, while Pb fractional desorption was lower, compared to Eu. These data suggest that Pb forms stronger binding and less reversible complexes than Eu. To simulate the specific sorption process of Pb and Eu, two surface complexation models (SCM), the diffuse-layer model (DLM) and the triple-layer model (TLM), were used to derive the primary sorption modeling parameters. Based on results of sorption data simulation, the TLM was selected to quantify the sorption behavior of Pb and Eu at the NTS.
DE: 1800 HYDROLOGY
DE: 1830 Groundwater/surface water interaction
DE: 1847 Modeling
SC: Hydrology [H]
MN: Fall Meeting 2005