Metal (Cu, Ni, Fe, Co, Zn, Pb) and Ra-226 levels in tissues of meadow voles Microtus pennsylvanicus living on nickel and uranium mine tailings in Ontario, Canada: Site, sex, age and season effects with calculation of average skeletal radiation dose

Abstract

Metal (Cu, Ni, Fe, Co, Zn, Pb) and Ra-226 levels were compared in several tissues of meadow voles Microtus pennsylvanicus of both sexes and differing age groups, collected seasonally on Ni and U mine tailings and at a control site. Seasonal variation of Cu levels in liver and Fe levels in kidney was observed at all sites (Fe in liver also varied seasonally at the Ni mine site). No variation by season in metal content of muscle was observed. Small sample size from the Ni mine location did not permit a firm conclusion to be drawn regarding sex and age effects on accumulation of these metals in soft tissues. Although Co and Pb in bone did not vary by sex or age group, Pb varied seasonally. Ra-226 concentrations in bone varied by age and season but not by sex. Levels of Ni, Co and Pb in soft tissues were below detection limits in most cases and firm conclusions on site effect could not be drawn. No site variation was observed in soft tissue levels of Cu. The Fe levels of liver and kidney tissue, in summer-captured voles from tailings high in Fe, were higher than those in animals from other sites. Lowest Zn levels were seen in kidneys of voles from the site with the lowest environmental levels of the metal. Bone content of Co did not vary by site. Skeletal Pb was highest during the summer and autumn on the uranium mine tailings while skeletal Ra-226 was highest for voles from that site during all seasons. Internal dose rate due to Ra-226 and cumulative dose at capture were calculated as 0·04 rad day −1 and 2·5 rad for animals captured in the spring, 0·009 rad day −1 and 0·6 rad for summer captures and 0·005 rad day −1 and 0·3 rad for those taken in the autumn.