title: Using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to characterize copper, zinc and mercury along grizzly bear hair providing estimate of diet.
abstract: We enhanced an existing technique, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), to function as a non-lethal tool in the temporal characterization of trace element exposure in wild mammals. Mercury (Hg), copper (Cu), cadmium (Cd), lead (Pb), iron (Fe) and zinc (Zn) were analyzed along the hair of captive and wild grizzly bears (Ursus arctos horribilis). Laser parameters were optimized (consecutive 2000 μm line scans along the middle line of the hair at a speed of 50 μm/s; spot size=30 μm) for consistent ablation of the hair. A pressed pellet of reference material DOLT-2 and sulfur were used as external and internal standards, respectively. Our newly adapted method passed the quality control tests with strong correlations between trace element concentrations obtained using LA-ICP-MS and those obtained with regular solution-ICP-MS (r(2)=0.92, 0.98, 0.63, 0.57, 0.99 and 0.90 for Hg, Fe, Cu, Zn, Cd and Pb, respectively). Cross-correlation analyses revealed good reproducibility between trace element patterns obtained from hair collected from the same bear. One exception was Cd for which external contamination was observed resulting in poor reproducibility. In order to validate the method, we used LA-ICP-MS on the hair of five captive grizzly bears fed known and varying amounts of cutthroat trout over a period of 33 days. Trace element patterns along the hair revealed strong Hg, Cu and Zn signals coinciding with fish consumption. Accordingly, significant correlations between Hg, Cu, and Zn in the hair and Hg, Cu, and Zn intake were evident and we were able to develop accumulation models for each of these elements. While the use of LA-ICP-MS for the monitoring of trace elements in wildlife is in its infancy, this study highlights the robustness and applicability of this newly adapted method.
authors.affiliation: Stantec Consulting Ltd. 2042 Mills Road, Unit 11, Sidney BC V8L 4X2, Canada. Electronic address: marie.noel@stantec.com.
authors.forename: Marie
authors.initials: M
authors.lastname: Noël
authors.affiliation: Stantec Consulting Ltd. 2042 Mills Road, Unit 11, Sidney BC V8L 4X2, Canada. Electronic address: jennie.christensen@stantec.com.
authors.forename: Jennie R
authors.initials: JR
authors.lastname: Christensen
authors.affiliation: School of Earth and Ocean Sciences, Bob Wright Centre A405, University of Victoria, PO BOX 3065 STN CSC, Victoria, BC V8W 3V6, Canada. Electronic address: jodys@uvic.ca.
authors.forename: Jody
authors.initials: J
authors.lastname: Spence
authors.affiliation: School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA. Electronic address: ctrobbins@wsu.edu.
authors.forename: Charles T
authors.initials: CT
authors.lastname: Robbins
mesh_terms: D000818:Animals; D003300:Copper / Q000032:analysis; D004032:Diet / Q000706:statistics & numerical data*; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D004785:Environmental Pollutants / Q000032:analysis*; D006197:Hair / Q000737:chemistry*; D008628:Mercury / Q000032:analysis; D019216:Metals, Heavy / Q000032:analysis*; D013054:Spectrophotometry, Atomic; D001503:Ursidae; D015032:Zinc / Q000032:analysis
chemical_list: D004785:Environmental Pollutants; D019216:Metals, Heavy; D003300:Copper; D008628:Mercury; D015032:Zinc
keywords: Diet; Exposure; Grizzly bear; Hair; LA-ICP-MS; Trace element