Naturally occurring estrogens in animal wastes may cause negative environmental impacts in some watersheds. However, there is little published data regarding the concentrations of these estrogenic compounds in full-scale animal waste treatment and storage structures, thus making risk assessment difficult. To address this knowledge gap, the research described in this paper explores estrogen concentrations in 19 animal waste storage and treatment structures at dairy and swine production facilities in and around Tennessee.
Samples have been collected from eight dairy and eleven swine facilities, representing a range of waste storage and treatment structures typical of Tennessee, and much of the southeastern US. The 17 ß -estradiol concentrations in all samples have been assayed in triplicate serial dilutions by means of an enzyme linked immunosorbent assay (ELISA), all samples have, or will be, assayed for conventional manure constituents, including total solids, volatile solids, ash, total Kjeldahl nitrogen (TKN), total phosphorus, potassium, and chemical oxygen demand. Concentrations of 17 a -estradiol, 17 ß -estradiol, and estrone are being assayed by gas-chromatography mass-spectroscopy (GC-MS), and total estrogenicity is periodically checked with a recombinant yeast reporter assay. At the time of this writing, the GC-MS dataset was incomplete, so that this paper is focused on the 17 ß -estradiol ELISA data.
Several tentative conclusions can be drawn from the preliminary data presented here, as follow: (1) 17 ß -estradiol concentrations are highest in swine finishing hoop structure solids and swine farrowing pit slurry, with concentrations in excess of 20,000 ppt (parts per trillion) observed in both systems. Average 17 ß -estradiol concentrations in swine farrowing and finishing lagoons were less than 4000 ppt. A similar trend was seen in dairy systems, where 17 ß -estradiol concentrations in dry stacks averaged 10,000 ppt, while concentrations in lagoons and holding ponds were below 2000 ppt. (2) The mass-ratio of 17 ß -estradiol to TKN followed a different trend than did the raw 17 ß -estradiol concentrations. For example, swine farrowing lagoons had the greatest ratio (ca. 25 ppm), while swine fishing hoop structure solids and swine farrowing pit slurries had ratios four times smaller. We believe that the mass-ratio of 17 ß -estradiol to application-rate-limiting macronutrients is a better predictor of the estrogen emission risk than is the raw 17 ß -estradiol concentration in the waste. (3) There is spatial heterogeneity in 17 ß -estradiol distribution within most structures studied. In 9 of the 11 liquid systems studied, a positive correlation was observed between 17 ß -estradiol and depth; in dry-stack dairy systems, older parts of the stack had lower 17 ß -estradiol concentrations than did newer parts of the stack.
Available at: http://works.bepress.com/raj_raman/34/