Using Rare Earth Elements (REE) to Determine Wind-Driven Soil Disperal From a Point Source.

Although erosion of soil by water is a predictably directional process, the erosion of soil by wind is determined by wind direction on an event-wise basis.  The wind-driven dispersal patterns of chemical constituents including natural soil components and anthropogenic contaminants are not well understood.  We applied a solution of Er(NO₃)₃ to a 5 m² (1.26 m radius) circle of soil in the center of a 50 m radius bare flat area of a field.  The application resulted in a three order magnitude increase in the soil concentration of Er in the application area.  We employed BSNE sampler masts with sampler openings at 5, 10, 20, 50, and 100 cm above the soil surface at radii of 5 m, 20 m, and 50 m from the center of the application area.  On the 5 m radius circle, the sampler masts were spaced at 60 degree intervals beginning with magnetic north and on the other two circles, the samplers were spaced at 30 degree intervals, resulting in a total of 30 sampler masts.  The samplers were collected weekly and the individual sampler catches were oven dried and weighed before being composited by location for acid extraction and subsequent analysis.  The extracts were analyzed by ICP and adjusted for volume of extract and weight of sediment extracted to yield Er concentrations on the displaced sediment.  The results indicate wind direction and variability are the dominant factors in determining the direction of eroded sediment movement.