Interactions between59Fe(III)-polyphosphates and clayey meadow soil

Interaction between iron(III)-diphosphate and iron(III)-triphosphate and Ca-form of a clayey meadow soil was followed over a period of three days using radiotracer technique and kinetic evaluation of the results performed.59Fe served to determine the quantity of iron,45Ca to measure the calcium, and phosphorus was measured spectrophotometrically. Approximately 80% of both iron chelates disappeared from the solution during the time of the experiment as a result of two well distinguishable reactions. One of them is a rapid interfacial process of about 10 minutes and the other is a slow reaction leading to the decomposition of iron(III)-polyphosphate chelates. The two processes could be separated using the Christiansen equation.