Lead Detection in Living Plant Tissue Using a New Histochemical Method

Abstract

A quick, simple method for identifying and distinguishing lead from other heavy metals in living plants has been developed using sodium rhodizonate (C₆0₆Na₂) which forms a scarlet precipitate with lead at approximately pH 2.8. Hand sections of plant tissues are treated with rhodizonate reagent, buffered, and examined microscopically. Very little time and/or effort is required for this method. Those cells and tissues contaminated with lead turn scarlet—color intensity being directly related to concentration. Lead may be detected in quite low concentrations and, most importantly, may be observed in situ; its entry and movement through the plant can thus be followed. In an area of moderate traffic of Downey, Calif. (Southeast Los Angeles), lead was found abundantly on leaves as well as on and in roots of garden-grown lettuce; origin of this lead is presumed to be from car exhausts.