MODEL TO PREDICT CONCENTRATION ENRICHMENT OF CONTAMINANTS ON SOIL ADHERING TO PLANTS AND SKIN

Transfer of soil contaminants into the food chain has long been a conc ern. However, certain aspects of the pathways involved have not been f ully investigated. One is the enrichment of contaminant concentrations through physical processes such as size-sorting of soil particles. Fi ne particles selected from soil by processes such as adhesion onto pla nts will have much higher contaminant concentrations than the original soil. A saturation kinetics model of the process of soil adhesion to leaf surfaces was developed. The model helps identify the parameters t hat are least-well known and need experimental support. The ratio of c lay and sand wash-off half times was especially important. With nomina l values for the input parameters, estimated enrichments agreed well w ith observations to date, and ranged from slightly over unity for medi um- and fine-textured soils to about tenfold for sandy soils. With a f ew reasonable assumptions, the model was generalised to apply to other soil adhesion scenarios such as adhesion to skin. The generalised mod el can be applied with minimal need for setting-specific information.