Pesticides are an essential component of modern agriculture and large quantities are applied annually on a global basis to arable land to prevent crop loss. After application, pesticides can be taken up by plants, degraded or distributed in the environment between the soil and in surface water or groundwater. Transport of pesticides in runoff and subsurface flow during rainfall events poses a significant concern for water quality with adverse effects on drinking water and aquatic life. Establishing the links between pesticide applications, hydrology, soil properties and erosion dynamics is key to understanding the fate of pesticides in the environment. This study has used a multi-scale approach combining laboratory experiments with a focused field campaign in a lowland agricultural catchment to investigate spatial and temporal pesticide dynamics at the catchment scale. The research provides methodological development for analysis of pesticides in soil, an understanding of the behaviour of pesticides in the soil and water environment after application due to rainfall and a catchment scale study of pesticide transport and distribution annually, seasonally and during individual storm events. First order controls on pesticide transport have been identified to partly explain the distribution of pesticides through a catchment and the upstream conditions required for pesticide movement. These include timing of application, quantity of pesticide available, antecedent soil moisture and rainfall, storm event characteristics, land use and season. An investigation of sediment-associated pesticides showed no significant quantities in stream-bed, reservoir bed or suspended sediment during storm events. The major risk factor for pesticide movement was found to be dissolved pesticides in storm event runoff. Results of this research can be used by farmers, water companies, regulatory bodies and scientists to improve water resource protection from field to catchment scales.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:682555 |
| Date | January 2014 |
| Creators | Harrison, Rebecca Victoria |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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