'Seaweed as an Exploration Medium along the Inlets of British Columbia - Part 2: Chemical Variations and Long-term Changes - Howe Sound.'

摘要

The rockweed Fucus gardneri lines the intertidal zone of inlets along much of the west coast of British Columbia and northwest USA. This rockweed is sensitive to the chemical signature of the stream waters that drain into the abundant inlets and, therefore, it can be analyzed to provide a focus to exploration activities by identifying areas with relative enrichments that might indicate mineralization. In 1991, 47 samples of rockweed were analyzed from sites around Howe Sound (Vancouver, British Columbia); in 2015, 34 sites from Howe Sound were resampled. On both occasions, there were strong enrichments of Cu and Zn from the former Britannia copper mine - but these were at much lower concentrations in 2015 after extensive long-term environmental remediation had taken place. There are also slightly elevated levels of Pb seaward from Britannia and greater dispersion of Ag. The latter may be partially associated with an enhanced Au signature on the west side of Howe Sound, and an attenuated As signature provides further evidence. Highest levels of Co and Cr occur at the northern part of the Sound. Rhenium and Na reflect the salinity of the seawater: concentrations weaken northward where there is a greater abundance of fresh water entering the Sound. Thus, the seaweed Fucus can be a useful exploration proxy for sources of metal enrichments and can also be used for long-term environmental monitoring.