*2.2. Stock Solutions and Reagents*

Stock solutions containing 1, 10, 20, 30, 40 and 50 mg Se(IV) L−<sup>1</sup> were prepared by diluting the appropriate amount of SeO2 in deionized water and were stored in airtight sterile glass containers. The desorbing solution of 0.25 M KCl was prepared by dissolving the proper amount of KCl salt in deionized water. This solution was also stored in airtight sterile glass containers.
