Fellow: Mary Schuh, Department of Soil Science, NDSU
Advisor:  Dr. Frank Casey, Associate Professor of Soil Physics, NDSU
Matching Support: NDSU
Degree Progress: M.S. in Soil Science expected in 2007

Background:

An apparent increase in physiological and reproductive disorders in animals has raised concern over the persistence of endocrine disrupting chemicals (EDCs) in the environment. Some studies have suggested that EDCs in the environment may adversely impact human health, where links between EDCs and increased breast cancer rates in women and decreased male fertility rates in men have been proposed. Land application of manures is one potential means of environmental exposure that could introduce hormones into surface or ground waters. Hormones are of concern because they are a potent EDC and can adversely affect aquatic organisms at very low concentrations (10 ng L -1) and have the potential of being widespread.

Project Objectives:

A previous study was conducted on a swine (Sus scrofa) farm in 2003, using lysimeters that were installed 60 cm below the soil surface. These lysimeters were used to monitor the amount of 17ß-estradiol, the primary female hormone, leaching through the soil of test plots treated with various types of manure. Based on known application rates and laboratory-determined fate and transport parameters, it was anticipated that all of the 17ß-estradiol would be metabolized or bound to the top 10 cm of soil. Instead, significant, albeit small, amounts of 17ß-estradiol were detected at depths of 60 cm and greater below the soil surface. It should be noted that the detected concentrations levels and the duration of persistence of the hormones would not cause biological disruption.

The objective of this project is to identify the causes of the 17ß-estradiol detections. Manure is a potential source of these hormones. Also, the soils in this area are derived from water deposited sand, are aquic, and have redoximorphic features within 16 cm of the soil surface. The high sand content may have increased the potential mobility of 17ß-estradiol. Redoximorphic features also indicate large fluctuations in the water table and periods of little or no oxygen. The high water tables can result in anaerobic conditions, which contribute to the persistence of 17ß-estradiol in the soil. During dry periods there is very little or no hormones present in the subsurface water. The research proposed will investigate the following hypotheses for causes: (1) There exists natural levels of background 17ß-estradiol from natural sources; (2) High water-table conditions cause a cool and anaerobic environment in which 17ß-estradiol persists; and (3) The ground water that contains the 17ß-estradiol is transporting exogenous hormones into the lysimeters in the soil horizon.

Progress:

Test sites have been selected and permission granted by the landowner to take soil cores around the area of interest. Soil cores will be taken to the depth of the water table before and after the manure is injected into the field. More cores will be taken through the growing season. Monitoring wells are located near all the sampling sites, so concentrations of hormones in the soil can be compared to that in the ground water. A plan for sampling and analysis has been formulated, where all the sampling materials are being assembled and procedures have been developed.

Significance:

This project will provide valuable information on the behavior of 17ß-estradiol and its metabolites, allowing an assessment of the effectiveness of natural restorative processes in the environment. It will help to define the interaction of soil and ground water with respect to the retention and transport of 17ß-estradiol. Furthermore, since 17ß-estradiol is a prototype for other EDCs, results will contribute to a general understanding of EDCs and other possible organic contaminants.