Calcium availability influences lead accumulation in a passerine bird

Abstract

AbstractThe emission of heavy metals in the environment is often accompanied by emissions of acidifying pollutants. The acidification of terrestrial ecosystems results in the leaching of calcium and consequently a lowered concentration or availability of this essential nutrient in the environment. Calcium deficiency in the diet may lead to an increased absorption of toxic metals. In this study we investigated the effect of calcium availability on the accumulation of lead and essential metals (calcium, copper, iron and zinc) in important target tissues of zebra finches (Taeniopygia guttata). When exposed to 20 ppm lead via drinking water, zebra finches excluded from an additional calcium supply (i.e. oyster shell grit) accumulated significantly higher concentrations of lead in liver, kidney, muscle, brain and bone than zebra finches with access to oyster shell grit. Levels of calcium, copper, iron and zinc were not significantly affected by either the calcium availability or the increased absorption of lead. There were no significant sex related differences, suggesting that males and females have a similar demand, metabolism and/or distribution of calcium and other metals in the non-reproductive period. This study clearly illustrates the importance of calcium supply on the bioavailability of lead.