EFFECT OF SURFACE CONTAMINATION ON RESULTS OF PLANT ANALYSIS

Chemical analysis of plants is often done without paying attention to the ubiquitous natural presence of exogenous material on the plant sur face. The analytical result will then be higher than the endogenous pl ant concentration. It is shown that this error can be related to three parameters: (i) the surface loading L, (ii) the enrichment factor (EF ) of the exogenous material with respect to the soil, and (iii) the pl ant-to-soil concentration ratio (CR). These factors are considered for 19 essential and trace elements and the results indicate that the err or can range from insignificant to disastrous. Experimental data are m ostly for needles of spruce trees growing in a relatively clean surrou nding, but the proposed relations can be extended to estimate the effe ct for other plant species and surroundings.