FATE OF IONIC THIOCYANATE (SCN-) IN SOIL

Ionic thiocyanate (SCN-) additions to soil result from anthropogenic and natural sources; however, little is known concerning the fate of this anion in soil. Six soils were amended with SCN- at concentrations expected from Brassica tissues. Thiocyanate in 0.005 M CaCl2 extracts was quantified using ion chromatography. The decrease in SCN- concentrations with time for incubations conducted at or below 30-degrees-C was positively correlated with soil organic carbon content in five of six soils. Autoclaving soils prior to incubation and adding NaN3 or allyl isothiocyanate slowed SCN- disappearance. Waterlogged conditions slowed disappearance initially, but the trend was not observed at 72 h. Extract concentrations of SCN- also decreased when the soils were incubated at higher temperatures of 50 or 60-degrees-C. Microbial degradation of SCN- is the main factor responsible for SCN- disappearance at or below 30-degrees-C. At higher temperatures decreases in extractable SCN- involve sorption or degradation by abiotic catalysis.