Sorption of selenium (IV) and selenium (VI) in a soil profile : An application of radiochemical techniques
Selenate was shown to be released from coal fly ash by water leaching at concentrations ranging from 1300 to 50 micro-g/l. If selenate is mobile in the soil water system it may reach hazardous concentrations in surface and ground waters. Adsorption and desorption studies with soil were carried out using two species of selenium labelled with radioactive isotope, i.e. Na(2)75SeO(4) and Na(2)75SeO(3). Experiments were performed in seven soil horizons going from the surface to the water table. Adsorption equilibrium was reached immediately between the selenium species, selenite and selenate, and the soil horizons with low organic carbon content (C soil horizons), but more slowly for the horizons with higher organic carbon content (A soil horizons). Linear isotherms were fitted to the sorption data. Sorption distribution coefficients ranged from 59 to 314 l/kg for selenite and from 3.2 to 14 l/kg for selenate. A maximum of 75 % of the initially absorbed selenate could be desorbed, compared with a maximum of 7 % for selenite. The sorption data provide information for modelling the transport of selenium in a real soil profile, and for designing larger lysimeter and field scale experiments.
Bibliographic Reference: Article: Journal of Trace and Microprobe Techniques, Vol. 11 (1993) Nos. 1-3, pp. 143-158
Record Number: 199410022 / Last updated on: 1994-11-28
Original language: en
Available languages: en