Fig. 2. Persistence of 1 mg kg^-1 [4-¹⁴C]-17ß-estradiol in a sandy loam soil (triangle), a silt loam soil (square), and a loam soil (circle) incubated at 30°C. Soils were adjusted to a moisture content of 13%. The soils were nonsterile (left panels) or autoclaved (right panels). Top panels: total extractable radioactivity expressed as a percentage of that initially applied. Middle panels: distribution of radioactivity in 17ß-estradiol (open symbols) and estrone (closed symbols) determined by high performance liquid chromatography (HPLC) with radioactivity detection, and expressed as a percentage of the total extractable radioactivity in that sample. Bottom panels: total estrogenic activity in soil extracts measured with the yeast estrogenicity screen (YES) bioassay, and expressed as 17ß-estradiol equivalents.