MERCURY IN PLANTS AND RETENTION OF MERCURY BY SOILS IN RELATION TO PROPERTIES AND ADDED SULFUR
Lettuce grown in a pot test using the surface soil layer of three golf course sites contaminated with mercurial fungicides contained up to 317 ng Hg/g as compared with no more than 36 ng Hg in plants grown in corresponding deeper soil layers containing much less Hg. In another experiment with 10 crop species, addition of phenylmercuric acetate to a loam soil at the rate of 5,000 ng Hg/g increased the Hg content of several of the species slightly over that found in the controls. The highest amount found was about 440 ng Hg/g in soybean vines and potato tops. The concentration tended to be lower in the edible portion (fruit, grain or roots) than in the remainder of the plants. In an incubation experiment where phenylmercuric acetate was added to seven soils and two clay-sand mixtures at the rate of 5,000 ng Hg/g, the retention of added Hg against volatilization varied from 41% in a sandy subsoil to 97% in a peat. Addition of flowers of sulfur was effective in preventing volatilization of Hg from the soils, but not from the clay-sand mixtures. Subsequent equilibration of the Hg-treated samples in 0.01 M CaCl2 removed only a minimal amount of Hg from one soil, but removed appreciable amounts from the clay–sand mixtures.