DETECTING HEAVY METALS IN FEATHERS WITH AN ELECTRON MICROPROBE

Using birds as environmental indicator species and analyzing their feathers for accumulated toxic elements is a well-established protocol. However, traditional methods, such as atomic absorption spectroscopy (AAS), condense and consume the entire sample. Consequently, it is difficult to differentiate findings between bioaccumulation inside and atmospheric deposition on the outside of the feather samples. This study attempts to expand the current literature by employing novel techniques and procedures; thus, the research objectives are two-fold: (1) to determine if and how feathers could be mounted for electron microprobe analyses; and (2) to qualitatively determine if mercury and other heavy metals could be detected in the feather sample using wavelength dispersive spectroscopy (WDS). This study was conducted at the Southeastern North Carolina Regional Microanalytical and Imaging Center (SENCR-MIC) located at Fayetteville State University. Primary flight feathers were obtained through the mist netting of live birds known to be nesting and foraging in habitats found within an EPA listed Superfund site in North Carolina. To limit the variables for this study, flight feathers were only sourced from the adult Carolina Wren (Thryothorus ludovicianus) species.

To first verify whether a feather could be sufficiently mounted for analysis using a JXA 8530F electron microprobe, a single segment was cut from the shaft of a sampled feather and mounted in epoxy. Mounting and polishing a sample must be done accurately to obtain quality results. WDS analysis was conducted on the electronic microprobe to detect the presence of mercury and cadmium within the shaft of the feather. Cinnabar (HgS) and Cadmium metal were used as standards. Samples were analyzed at an accelerating voltage of 20 kV and a beam current of 50 nA. Findings confirmed the presence and location of both mercury and cadmium in the feather sample. Continued exploration of this analytical method applied to feathers may provide insight into differentiating between internal bioaccumulation of environmental contaminants and external atmospheric deposition because this technique allows for a visual representation of electron activity. Concomitantly, additional work is needed to develop procedures for quantifying amounts of detected heavy metals.