Transport processes in hydrous oxide

Radionuclide transport in natural waters is strongly dependent on sorption, desorption, dissolution, and precipitation processes. The first two sections discuss laboratory investigations of these processes. Descriptions of sorption and desorption behavior of important radionuclides under a wide range of environmental conditions are presented in the first section. Among the sorbents studied are basalt interbed solids, granites, clays, sediments, hydrous oxides, and pure minerals. Effects of redox conditions, groundwater composition and pH on sorption reactions are described. 

The effect of both physical and chemical processes on the parental materials prior to and during transport will influence particle size ranges and therefore accessory mineral and clay content, which in turn control many aspects of trace element chemistry. The higher concentrations of most trace elements in the finer dust fractions can be explained in terms of reduced quartz dilution effects and higher phyllosihcate and hydrous oxide contents. 

Cation and anion adsorption by hydrous metal oxides influence several processes of environmental concern including contaminant transport, nutrient availability, and mineral dissolution rates (i,2). Various factors influence the amount of a particular ion adsorbed including solution pH, type of oxide and its surface area and crystallinity, time, ionic strength, properties and concentration of the adsorbing species, and competing species. These factors have received various degrees of scrutiny in previous studies. Temperature is another potentially important variable but has not to date received as much... 

---