Sorption and Aerobic Biodegradation of Strychnine Alkaloid in Various Soil Systems

Abstract

Strychnine alkaloid was demonstrated to sorb strongly to several western soils that varied in organic matter and ranged in texture from a loamy sand to a sandy clay loam. Freundlich sorption coefficients (K) for the test soils varied from 40 to 169. A direct relationship was observed between strychnine sorption and cation exchange capacity but not between sorption and organic matter content. Strychnine sorption was only partially reversible (12−44%). Degradation of 10 μg/g strychnine in sandy loam and sandy clay loam soils occurred in three distinct phases, which included a lag phase, a rapid loss phase, and a leveling off or soil binding phase. Approximately 50% of the strychnine was lost from the two soils within 24−27 days, with the appearance of a degradation product occurring early in the study. The initial breakdown products of strychnine are believed to be polar compounds with strong sorption characteristics. Keywords: Strychnine; soil sorption; degradation; breakdown products