Mapping and interpreting soil textural layers to assess agri-chemical movement at several scales along the eastern seaboard (USA)

Abstract

Despite numerous cases of groundwater contamination with agricultural chemicals on layered sandy soils, monitoring and prediction of the fate of these chemicals in the vadose zone has eluded researchers and bureaucrats alike so far. To aid in a better understanding of this phenomena, the movement and fate of agricultural chemicals were assessed at different scales for the (sandy and layered) floodplain soil occurring along the Eastern Seaboard. At the point and field scale ground penetrating radar was used to locate the coarse sand lenses and tracer experiments were initiated to study the flow pattern of the chemicals. Results show that water and solutes moved over the coarse layers and were funneled into fingers bypassing most of the soil matrix and reaching the groundwater much faster than when the solute would move evenly through the vadose zone. At field scale a computer simulation indicated that the exact location of the layers does not have to be known for calculating travel times, indicating that pedo-transfer functions could be developed for calculating groundwater pollution potential for different combinations of soil and chemicals. In the future, groundwater pollution on a regional scale can be predicted by using these pedo-transfer functions in a Geographic Information System.