A novel multi-coloured method for tracing several different sizes of colloid at once was developed using fluorescently dyed latex polystyrene microspheres and employing a solvent dissolution method (SDM) developed from that used in bio-medical research for the detection of these tracers. The use of this method means that both the breakthrough characteristics, and colloidal mobilisation and deposition patterns within the soil profile, can be investigated as it allows detection of the micro sphere tracers in both water and soil samples. A series of laboratory based rainfall simulation experiments carried out on a four large intact soil cores showed that the four sizes of fluorescent microsphere used in this research (1.2Ilm, O.8Ilm, OAllm and O.2Ilm) could mimic the behaviour of the corresponding size fractions of both TP and MRP extremely successfully, though the correlation was stronger for TP. These experiments also showed that the colloidal and colloid-borne P could make a significant contribution to phosphorus losses from agricultural soils. Further, a high proportion of all four size fractions were found to be molybdate reactive, indicating that current water quality monitoring which uses MRP<OA5Ilm as a measure of bioavailable P in surface waters may result in serious underestimation. The potential impact of phosphorous losses from diffuse sources through unsaturated vadose zone soils on ecological water quality may be considerably greater than previously thought. Finally a series of similar rainfall simulations on large intact soil blocks, with special grid collection systems at their base, allowed the complex and dynamic nature of active flow pathways through unsaturated vadose zone soil, and the impact this has on colloidal mobilisation, transport and deposition, to be explored.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:555231 |
| Date | January 2011 |
| Creators | Sinclair, Hazel Anne |
| Publisher | University of Sheffield |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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