Monitoring spatially resolved trace elements in polar bear hair using single spot laser ablation ICP-MS

Abstract

Elements and compounds circulating in the body are incorporated into hair as it grows. Because of this, hair analyses are increasingly being incorporated in investigations of temporal trends in e.g. hormones and diet in wildlife species such as polar bears (Ursus maritimus).For this study, guard hair (GH; mean length 62 mm) and foreleg guard hair (FGH; mean length 164 mm) were collected from 15 adult male polar bears in western Hudson Bay, Canada. Our aim was to quantify the trace elements arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), mercury (Hg), selenium (Se), strontium (Sr), and zinc (Zn) every 3 mm in GH and FGH using laser ablation inductively coupled plasma mass spectrometry (laser ablation ICP-MS).Quantitative data was obtained at spatial scales as small as 50 μm – the smallest laser spot diameter used. Mean trace element concentrations increased in the order Pb < As < Cd < Se < Hg < Cu < Sr < Fe < Zn for both GH and FGH (pooled across all individuals). However, mean trace element concentrations were all significantly different between GH and FGH, except for Hg. Hg concentration varied along the length of both GH and FGH; each bear exhibited a unique pattern in Hg variation along the hair. For the remaining eight trace elements, the most common pattern was that of smaller fluctuations near the base of the hair, followed by an increase towards the tip. These fluctuations in trace element concentrations were likley related to hair growth and temporal changes. In this pilot study, we found quantifying trace elements in polar bear hair using laser ablation ICP-MS to be a promising monitoring technique across multiple temporal scales.