PERSISTENCE AND MOBILITY OF ESTROGENS IN THE ENVIRONMENT
Animal Metabolism-Agricultural Chemicals Research
Project Number: 5442-32000-014-01
Start Date: Dec 01, 2009
End Date: Nov 30, 2013
All animals produce natural hormones in the healthy function and regulation of their endocrine system. When a hormone is eliminated from the body and gets into the environment, it can act upon other animals as an endocrine disrupting compound by binding to and activating receptors within hormone-responsive organs. In sensitive organisms this can occur at the parts per trillion level, and risks include sex reversals and cancer. The potential for livestock farms to serve as sources of hormones to the environment has been recognized for many years. To guide the objectives of this proposal, the following research questions (RQ) were formulated to evaluate the respective testable hypotheses (TH):
RQ 1) Does dissolved organic carbon and particulates from lagoon waste or soil enhance the mobility of estrogens in mineral soil and thus increase the potential for off-site movement?
TH 1) If the movement of estrogens is related to the presence of lagoon- or soil-derived dissolved organic carbon and particulates, then estrogen in the presence of high amounts of soil/lagoon dissolved organic carbon will increase their mobility compared to aqueous free estrogens.
RQ 2) Does dissolved organic carbon and particulates of lagoon waste or soil offer estrogenic hormones protection from microbial degradation and increase their longevities in the soil or manure storage facilities?
TH 2) If estrogenic hormones are bound to dissolved organic carbon or particulates and not easily accessible to microbial processes, then hormone in the presence of high amounts of dissolved organic carbon or particulates will increase persistence in the environment compared to free aqueous hormone.
RQ 3) Do estrogen conjugates (i.e. polar metabolites) promote the mobility or persistence of estrogens in soil?
TH 3) If conjugated hormones are more water soluble than their de-conjugated forms, then they are also more mobile in the soil and can potentially migrate to areas of reduced microbial degradation.
RQ 4) Do estrogens and their conjugates from lagoon waste applied to fields move into groundwater and into surface waters?
TH 4) If the mobility of estrogens in soil is dependant on hormone conjugation, the presence of dissolved organic carbon or particulates, and the low retention time in upper soil layers, then application of manures on tile drainage fields will increase the presence of hormone/hormone conjugates in ground and surface waters.
To answer these research questions and test the hypotheses, the following experimental objectives were formed:
Objective 1 – Determine the sorption characteristics of estradiol, estradiol glucuronide and sulfate conjugates with particulates originating from natural organic matter from soil and from animal manure lagoon liquors (laboratory);
Objective 2 – Determine the degradation of the parent compounds estradiol, estradiol glucuronide and sulfate conjugates in the presence of these particulates and soil (laboratory); and
Objective 3 – Determine how land application strategies (surface applied vs. injection) for lagoon liquor influence the fate and transport of estradiol in a field setting.
Objective 1: Degradation of hormones is mediated primarily by biological activity and can lead to misinterpretation of observed physical/chemical soil absorption processes. In order to identify these processes experimentally, the experiments for this objective will be conducted under sterile conditions. Four hormone concentrations and nine time points will be used and sampled. Qualititative and quantitative assessment of hormone degradation and soil absorption will be made by chromatographic and spectrometric methods, and absorption curves and models can then be determined. Objective 2: High and low organic soils will be spiked with radioactive hormone conjugates with and without lagoon waste under aerobic/anaerobic and sterile/non-sterile conditions to measure biological degradation in soil. Mass balances, qualitative assessment of hormone fate, and separation of hormone compartments into the various soil fractions under these conditions will be determined. Objective 3: Well-defined field-scale Discovery Farms will be used to measure the transport of hormones when injected into soil and followed by uncontrolled and controlled drainage (rainfall). Both well water and soil extracts will be analyzed for hormone content across two growing seasons.