PH16 Ecological Risk Assessment and Landscape Ecological Modeling
Exhibit Hall
8:00 AM - Thursday
(PH190) Examination of the control of agricultural estrogen releases in the context of the TMDL approach using the TEAR model.
Mackay, Chris1, 1 Exponent, Bellevue, WA, USA
ABSTRACT- Estrogen release to surface water is growing environmental problem. Most of the concern has surrounded releases from municipal waste treatment facilities. However, another source that, in some areas, may dwarf estrogen loading from humans is concentrated animal feeding operations (CAFOs). Only recently have CAFOs in the U.S. come under general permitting requirements, and that has primarily involved the control of nutrient releases. Estrogen releases have therefore categorized as nonpoint sources, with the TMDL approach used to protect environmental quality. In this presentation, the use of estrogen TMDLs relative to CAFO-based estrogen sources is examined using the Thermodynamic Estimation of Aquatic Response (TEAR) model. The most important factors affecting the magnitude of impacts to fish populations are the residence time and transport velocity of estrogen-containing liquors from land applications as runoff (surface or groundwater) to adjacent surface water bodies. Results indicate that springtime applications of manure coincide with the most sensitive time of fish reproduction. However, some attenuation of the potential impact occurs because of seasonal flow patterns. The greatest attenuation of potential impact occurs in situations where peak transport to the surface water body occurs in mid to late winter. Some of the estrogen-containing material is then removed by the early spring flushes prior to the start of most species' reproductive cycle. This is particularly important in small to medium tributaries that tend to have the lowest dilution rates, and are most likely to receive the first influences from CAFO-type facilities.
Key words: Estrogen, Endocrine Disruptors, TMDL, Agriculture