Geochemistry / Sequential extraction of a contaminant in a given context.

Question 4 Context You are a civil or geological engineer working on a contaminated soil. Through tests, you learn that the main reason for contamination is Zn. a) Which reactive would be appropriate to know the fraction of soluble Zn in the soil solution? b) Now, we are searching to separate the ZN from the changeable fraction. We can either use 0,5 of KNO3 or 0,5 M of MgCl2. In the case of those two reactives, precize the cations exchange. Additionaly, which reactive will extract the most amount of Zn? c) Which reactive and procedure of extraction will be used to establish the measurement of the total amount of Zn? Describe how it works