Overland Flow Using Rare Earth Element

14 15 Rare earth element oxides (REOs) have excellent potential for use as tracers in 16 erosion studies. Using laboratory and field experiments we aimed to develop and test 17 a simple application method for spreading REOs and to use REOs to determine the 18 source of sediment to concentrated overland flow paths. 19 Tracks left by farm machinery (tramlines) in fields act as concentrated flow 20 paths, delivering a large amount of surface runoff and entrained sediment to the field 21 boundary however little is known regarding where this sediment is sourced from. 22 Two field experiments were conducted to investigate this, one looking at whether 23 Stevens and Quinton 2008 Catena 74 31-36 3 sediment is entrained from different points along the length of the tramline and one 1 looking at the area over which sediment is entrained from either side of a tramline. 2 Results from leaching tests and rainfall simulations clearly demonstrated the 3 potential of this method for tracing sediment, there was very little movement of REOs 4 through the soil profile and they were transported with sediment in overland flow. 5 In the field experiment a large proportion of the sediment transported in the 6 tramline originated within the first metre either side of it. However, the total area 7 over which eroded sediment collects and flows into the tramline is potentially large 8 with small amounts of sediment eroded from the between four and six metres being 9 transported in the tramline. 10 REOs have an excellent potential for use as a tracer of soil erosion. They 11 provide a quick and cheap method of identifying sources of eroded sediments and 12 have good potential for use in determining erosion rates. 13 14