The work in this thesis is divided into two discrete sections: the first describes the behaviour of estrogenic pollutants in soil, whilst the second describes the development of a nitrate and turbidity sonde for use in monitoring pollutants in groundwater boreholes.
Endocrine disrupting chemicals are of increasing concern due to their effects on aquatic organisms especially the feminisation of male fish. Some of the chemicals of concern are naturally occurring steroid hormones such as estrogens (reviewed in Chapter 2). Investigations into the biodegradation of the estrogens: estrone and 17 β-estradiol (published in the journal Soil Biology and Biochemistry; Chapter 3) were undertaken, alongside investigations into the sorption of the estrogens to soil (Chapters 3 and 4) and their ability to be leached through the soil profile during rainfall events (Chapter 4).Throughout these investigations ¹⁴C-labelled estrogens was applied to different soils in various animal wastes. It was concluded that the estrogens were mineralised rapidly in soil and they behave differently when applied to soil in urine rather than water, which has implications for future work. Groundwater is an important resource for water supplies in the UK. The most common pollutant is nitrate, as reviewed in Chapter 5. UV spectrophotometry was investigated in the laboratory to develop a standard nitrate analysis method (Chapter 6). A major interference in nitrate measurement with UV in natural waters is dissolved organic carbon (DOC), which has an absorbance in the same range as nitrate (Chapter 7). Following laboratory development and calibration with humic acids to overcome the complications arising from DOC a field sonde was developed using UV spectrophotometry (Chapters 8 & 9). A separate sonde was developed to evaluate turbidity in natural waters. Chapter 10 shows the laboratory and field tests involved with the turbidity sonde, the work that goes into developing a new product and the results obtained.
There are many further experiments that could be developed from the work in this thesis. In the estrogen section experiments need to be carried out with intact soil cores and in the field with conditions that cannot be achieved in a laboratory. To put the work into a more global context different animals, agricultural practices, climate and geography would need to be considered. In the nitrate section future work includes the continued testing of the nitrate and turbidity sondes. There is also the possibility of developing a DOC sonde and the potential of phosphorus measurement could be explored.