An investigation into Manganese(2+) interferences and retrospective dose assessment of shelled species using EPR spectroscopy

Abstract

High intensity Mn²⁺ peaks in calcified tissues of shells are known to impact the lower dose detection limit in retrospective electron paramagnetic resonance (EPR) studies. This thesis investigates the factors causing Mn²⁺ accumulation in shells including crystalline structure and animal habitat. Inductively coupled plasma - optical emission spectroscopy (ICP-OES) was used to determine the Mn²⁺ concentrations in shells of thirteen species. A methodology to quantitatively compare Mn²⁺ concentrations with Mn²⁺ EPR peak intensity in calcified shells was developed as a potential indicator tool for selecting shelled species for EPR dosimetry. This comparison found that shells of zebra mussels, grove snails, and heath snails were best suited as environmental dosimeters due to their low Mn²⁺ concentrations and Mn²⁺ EPR peaks. Dose-response curves for grove and heath snails were developed by irradiating shells to 2, 3, 5, 7, and 10 Gy. Both species had minimum detectable doses of 2 Gy.