Determination of diffusion coefficients associated with the transport of210Pb radionuclides in lake bed sediments

An iterative least-squares optimization technique is utilized in conjunction with a one-dimensional representation of the mass transport equation to generate theoretical²¹⁰Pb concentration/depth profiles beneath the water-sediment interface that are best-fit approximations to directly measured²¹⁰Pb concentration/depth profiles at various locations within the Great Lakes system. The outputs of such an optimization analysis are the diffusion coefficientsD _M (molecular) andD _B (bioturbation) associated with the transport of²¹⁰Pb radionuclides in lake bed sediments. For all stations studied, the estimated values ofD _B are consistently larger than the estimated values ofD _M , emphasizing the importance of accounting for the effects of bioturbation in the modelling of contaminant transport through lake bed sediments.