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Cadmium Isotope Fractionation During Adsorption onto Manganese Oxides. Gabriela Montañez Mentors: Laura Wasylenki and Ariel Anbar. Nutrient to some marine organisms Toxic metal in environment. Manganese oxide. Why adsorption?.
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Cadmium Isotope Fractionation During Adsorption onto Manganese Oxides Gabriela Montañez Mentors: Laura Wasylenki and Ariel Anbar
Nutrient to some marine organisms • Toxic metal in environment
Manganese oxide Why adsorption? • Adsorption to particles governs cadmium concentration in natural waters • Cadmium is immobilized if strongly adsorbed • Will cadmium isotopes fractionate during adsorption? Cd2+ Cd2+ Cd2+ Cd2+ Cd2+ Cd2+ Cd2+ Cd2+ Cd2+ Cd2+ Cd2+ Cd2+
What are isotopes? • Isotopes are atoms of an element that have the same number of protons but different numbers of neutrons • Cadmium has isotopes of mass 106, 108, 110, 111, 112, 114, 116 • Will light or heavy isotopes preferentially adsorb to manganese oxides?
Seawater vs. natural ferromanganese crusts • Horner et al. (2008) sampled ferromanganese sediments and seawater at depth • No fractionation was found • What would a simple controlled laboratory experiment show?
Cadmium stock MnOx stock pH ~ 6 Procedure Measure isotope ratio on solution and solid after separation
Mass Spectrometer 108 114
Fractionation! 114/108Cd (‰)
Implications and Future Work • Fractionation tells us that the isotopes might give us a new tool to track cadmium as it moves between water and sediments in the environment • Next steps: • try adsorption to other minerals • find contaminated aquifer to investigate cadmium isotope variations in the real world