Mossbauer Study of the Attenuation of Iron in an Irrigated Greensand Lysimeter

-Fe 57 Mfssbauer spectroscopy has been used to determine the nature of iron-containing minerals in Lower Greensand samples from an experimental lysimeter at Uffington, Oxfordshire, both before and after a three-year irrigation with a synthetic heavy metal leachate. Analysis of the spectra measured at 300 ~ 77 ~ and 4.2~ and at 4.2~ in an applied field of 45 kOe shows that iron is present in the uncontaminated sandstone in fine-grained goethite (a-FeOOH) and glauconite. In the irrigated samples iron is precipitated as a fine-grained ferric hydroxide gel having values for the hyperfine field at 4.2~ of 435 and 470 kOe. The stability of the gel over the three-year period of irrigation may be explained by surface energy considerations. Key Words--Glauconite, Goethite, Greensand, Iron, Lysimeter, M/Sssbauer spectroscopy.