Comparative kinetics of cesium from whole-lake, limnocorrals, and laboratory-scale experiments

¹ Savannah River Ecology Laboratory, University of Georgia, Aik En, SC 29801, U.S.A.
² Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, U.S.A.

Abstract

Understanding the processes governing a contaminant's transport is difficult in uncontrolled field experiments; however, controlled laboratory experiments are often contrived and may quickly loose realism. Knowing how well small-scaled, laboratory experiments mimic those from full-scale field manipulations is of fundamental importance. We compared the loss of cesium from a lake's water column at four different scales: 1) an 11 ha lake; 2) five, 1.2-m diameter limnocorrals; 3) four, 30-cm diameter limnocorrals; and 4) four, 30-cm diameter laboratory mesocolumns. Limnocorrals were installed in 1 to 2 m of water and at two different areas within an 11 ha lake. All limnocorrals were sealed to the lake sediments, allowed free exchange with the air, but isolated a column of the lake's water. Laboratory mesocolumns were plastic cylinders, closed on one end, and had 15 cm of sediments placed in them, topped with 90 cm of lake water. The monomictic lake had a mean and maximum depth of 1.6 and 4 m, respectively. Stable Cs was added to the epilimnion of the whole lake, and to the limnocorrals and mesocolumns. The loss rate of cesium from the water column of each system was compared over time. The data are useful for determining how well small-scaled experiments simulate water/sediment exchange processes occurring in wholelakes.