| Abstract: | A new method has been developed for the determination of adsorbed on sediments. The method utilizes sediments directly in a closed loop counting system and measures the daughter . Because the recoil path length of is small compared to the sediment particle size, adsorbed is released to the gases circulating in the closed loop counting system and produced internally within the sediment particles is effectively excluded. The method has been calibrated against (1) multi-step Na+ displacement of and (2) multi-step Zn2+ replacement of . It has been found to accurately quantify the adsorbed component with a significant savings in laboratory time and with greater precision. Combined with dissolved measurements of the porewater, distribution coefficients can be accurately calculated. This method has potential for direct application to water column balances in estuaries, coastal water and salt marshes. When used to extract the reactive transport dynamics of in the sediment, the method may have applications to trace metal transport in sediments. |
