Rattlesnake Ridge interbed

Two interbed samples, a sandstone and a tuff, were taken from as outcrop of the Rattlesnake Ridge Interbed above the... 

Source Rattlesnake Ridge Interbed Mabton Interbed Rattlesnake Ridge Interbed... 

Beneath this sequence, which in total is usually referred to as the unconfined aquifer system, lie Columbia River basalt flows, which contain their own series of confined aquifers. The uppermost confined aquifer in the basalt sequence may be formed either by flow tops in the Elephant Mountain Member or by the Rattlesnake Ridge interbed and underlying Ponoma flowtop zone. 

Within the Columbia River Basalt Group, the Rattlesnake Ridge Interbed and underlying Pomona flowtop zone form the uppermost confined aquifer in most locations. The Rattlesnake Ridge Interbed consists of 14 to 18 m (45 to 60 ft) of tufaceous silt, stone, and sandstone. The Elephant Mountain Member, which is found throughout the 100 Areas, forms the confining layer above the Rattlesnake Ridge Interbed. 

Procedures. Batch equilibrations of interbed solids (Mabton Interbed, Rattlesnake Ridge sandstone, or tuff), tracers, and groundwaters were used to measure radionuclide distributions between solid and liquid phases. Triplicate measurements were made for each combination of temperature, redox condition, tracer concentration, tracer type, groundwater composition, and interbed sample. Constant temperatures were maintained by placing the... 

Tin and americium were so extensively sorbed under all conditions that isotherm data could not be obtained. These elements are not significantly mobile in the Mabton Interbed aquifer. Values of Freundlich constants for technetium, radium, uranium, neptunium, and plutonium are given in Table IV. The Freundlich equation did not fit the selenium sorption data very well probably because of slow sorption kinetics or precipitation. Precipitation was also observed for technetium at 23°C for concentrations above 10 7M. This is about the same solubility observed for technetium in the sandstone isotherm measurements. Linear isotherms were observed only in the case of radium sorption. In general, sorption on the Mabton Interbed was greater than on the Rattlesnake Ridge sandstone. This is probably due to the greater clay content of the Mabton standard. 

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