An automated groundwater monitoring system for the detection of uranyl ion in groundwater was deployed at the 300 Area Industrial Complex, Hanford Site, Washington. The research was conducted to determine if at-site, automated monitoring of contaminant movement in the subsurface is a viable alternative to the baseline manual sampling and analytical laboratory assay methods currently employed. The monitoring system used Arsenazo III, a colorimetric chelating compound, for the detection of the uranyl ion. The analytical system had a limit of quantification of approximately 10 parts per billion (ppb, µg/L). The EPA’s drinking water maximum contaminant level (MCL) is 30 ppb [1]. In addition to the uranyl ion assay, the system was capable of acquiring temperature, conductivity, and river level data. The system was fully automated and could be operated remotely. The system was capable of collecting water samples from four sampling sources, quantifying the uranyl ion, and periodically performing a calibration of the analytical cell. The system communications were accomplished by way of cellular data link with the information transmitted through the internet. Four water sample sources were selected for the investigation: one location provided samples of Columbia River water, and the remaining three sources provided groundwater from aquifer sampling tubes positioned in a vertical array at the Columbia River shoreline. The typical sampling schedule was to sample the four locations twice per day with one calibration check per day. This paper outlines the instrumentation employed, the operation of the instrumentation, and analytical results for a period of time between July and August, 2012. The presentation includes the uranyl ion concentration and conductivity results from the automated sampling/analysis system, along with a comparison between the automated monitor’s analytical performance and an independent laboratory analysis.
[1]
Michael D Annable,et al.
Field-scale evaluation of the passive flux meter for simultaneous measurement of groundwater and contaminant fluxes.
,
2005,
Environmental science & technology.
[2]
Jay W Grate,et al.
Equilibration-based preconcentrating minicolumn sensors for trace level monitoring of radionuclides and metal ions in water without consumable reagents.
,
2006,
Analytical chemistry.
[3]
J. Grate,et al.
Automated radioanalytical system for the determination of 90Sr in environmental water samples by 90Y Cherenkov radiation counting.
,
2009,
Analytical chemistry.
[4]
Kenneth M. Krupka,et al.
Geochemical Data Package for the 2005 Hanford Integrated Disposal Facility Performance Assessment
,
2004
.
[5]
H. E. Rohwer,et al.
Complexation reactions of uranyl with arsenazo III
,
1997
.
[6]
Mary J. Hartman,et al.
Automated Ground-Water Sampling and Analysis of Hexavalent Chromium using a “Universal” Sampling/Analytical System
,
2005,
Sensors (Basel, Switzerland).
[7]
J. Grate,et al.
Quantification of technetium-99 in complex groundwater matrixes using a radiometric preconcentrating minicolumn sensor in an equilibration-based sensing approach.
,
2009,
Analytical chemistry.