Evaluation of the in situ, time-integrated DGT technique by monitoring changes in heavy metal concentrations in estuarine waters
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Various natural and anthropogenic processes influence heavy metal concentrations within estuaries. In situ, time-integrated DGT measurements made over concurrent tidal phases found significantly higher concentrations of Cu (probability p = 0.017), Zn (p = 0.003) and Ni (p = 0.003) during the flood phase, because the incoming tide passes several point sources. DGT-reactive Cu concentrations significantly decreased with increased tidal-flushing and vice versa within a marina (correlation r = -0.788, p = 0.02). DGT measurements also recorded significant increases in Cu (4 out of 4 sites, p < 0.001) and Zn (3 out of 4 sites, p = 0.015) after a 24 mm rainfall event. Finally, DGT-reactive Cu increased significantly (p < 0.001) during peak boating times, due to increased numbers of Cu-antifouled boats. This study demonstrates that, with judicious selection of deployment times, DGT measurements enable changes in heavy metal concentrations to be related to various cycles and events within estuaries.
© 2007 Elsevier. Please refer to the journal's website for access to the definitive, published version. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher.