ASTM D5435-13

5.1 The bioavailability of chemical elements is poorly related to the chemical composition of soils and plant growth media containing a mineral or any type of adsorbed phase. The chemical potential (pi for element, i,) is an intensity parameter (I), and the sorbed amount in equilibrium with the soil solution is a measure of the quantity (Q). These parameters for each element (essential or toxic) should be measured in the presence of other elements at or near the desired intensity. This test method is the only method that generates these results simultaneously for several elements. The computer software allows these values to be related to the total sorbed quantities of the different elements. For many substrates, it has been found that the theory for the method holds to the degree that vegetation has been established on many non-soil substrates and soil-water-food chain problems have been evaluated by this test method. This test method has been used on many sites in Pennsylvania and other locations to monitor the effect of sewage sludge applications on land as a source of essential elements for plants with no harmful effects on the food chain. It has also been used to evaluate synthetic soils produced from fly-ash alone or as a component of coal refuse for the establishment of vegetation on mine spoils, coal refuse piles, and abandoned mine lands.