Solution and laser ablation inductively coupled plasma–mass spectrometry measurements of Br, I, Pb, Mn, Cd, Zn, and B in the organic skeleton of soft corals and black corals

Abstract

Proxy records can be derived from soft corals and black corals using minor and trace element measurements of the organic skeleton of these corals. Here, concentrations of Br, I, Pb, Mn, Cd, Zn, and B in the organic skeleton were determined using solution inductively coupled plasma–mass spectrometry (ICP‐MS) in one black coral from 5 m depth and two soft corals from 85 and 105 m depth collected from a reef offshore of Palau in the western tropical Pacific. Solution ICP‐MS results indicate that concentrations of some elements vary as expected with depth (Cd and Mn) while others are taxa specific (I) or colony specific (Br, Pb, Zn, and B). The intensities of the same elements normalized to 13C were also measured at high resolution using laser ablation (LA) ICP‐MS along radial transects covering the lifespan of the colonies. The results here indicate that high‐resolution LA ICP‐MS elemental records in black corals could be more fully developed for paleoceanographic reconstructions. In contrast, results of the laser transects from the two soft corals were not reproducible for any of the elements, and no discernible patterns were detected that could be developed into reliable proxy records using the current LA ICP‐MS method.