Environmental Fate of Manure-Borne Estrogens and Pathogens Applied to Agricultural Land: Effect of Slurry Separation.

Contamination of freshwater by pathogens and estrogens in liquid manure applied to agricultural land is of great concern because of their potential for deleterious effects on aquatic life and human health. Recent advances in manure management include partial removal of dry matter by separation technologies. This may remove both pathogens and estrogens from the slurry and enhance infiltration upon field application and hence the interaction between contaminants and the soil matrix. A sorption study investigated how 17β-estradiol (E2), a natural estrogen commonly found in pig manure, sorbs to agricultural soils, to different size fractions of particles in pig slurry, and to soils amended with each size fraction under slurry-treated soil conditions. Sorption increased with the organic carbon content of the soils. Slurry separates showed high, but varying sorption relative to soil. Mixing slurry separates with soil increased the sorption of E2 significantly. In contrast, dissolved organic matter of slurry reduced the sorption to the soils by increasing the attachment of E2 in the liquid phase. The redistribution and persistence of pig manure-borne pathogens after direct injection to soil was investigated in a field study, where the spatial distribution of Escherichia coli and Salmonella Typhimurium Bacteriophage 28B in and around the injection slit was measured on day 0, 1, 6, 18, and 46/49 in sandy clay loam and sandy loam soil. Transport of slurry components away from the slit varied significantly with slurry dry matter content and soil conditions. Survival of E. coli was high in the upper layer of both soils. Overall persistence of bacteriophage was higher than that of E. coli, but both organisms were still observed after 49 days of slurry application. Slow downward movement was noticed for an extended period at both sites due to precipitation events. A laboratory leaching experiment with different slurry types and application methods examined the leaching potential of several manure-borne pathogens. E. coli leaching varied significantly for different slurry application methods.