THEORETICAL AND EXPERIMENTAL-ANALYSIS OF PEEPER EQUILIBRATION DYNAMICS

Peepers are multichambered equilibrium dialyzers placed within sedimen ts to collect porewater samples. We developed computer models to study the equilibration dynamics of a vial peeper design. One model simulat ed the concentration distributions and dynamic behavior of solute with in the peeper cell itself, and another simulated the equilibration of peepers placed within sediments. The first model, together with labora tory experiments, demonstrated that convection arising within peeper c ells placed in saline sediments would ensure rapid mixing of the conte nts of the cells. The predictions of equilibration behavior made by th e second model for four chemical species (K, Na, Ca, and Sr) generally compared well with the results of laboratory experiments. These resul ts showed that peeper equilibration was limited almost wholly by solut e diffusion through the sediments and demonstrated the importance of p eeper dimensions and solute diffusivities for equilibration times.