Sediment-Bound Inorganic Hg Extraction Mechanisms in the Gut Fluids of Marine Deposit Feeders

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Pages (from-to)6181-6186
Journal / PublicationEnvironmental Science and Technology
Issue number19
Online published2 Sep 2006
Publication statusPublished - 1 Oct 2006
Externally publishedYes


The contributions of different free amino acids and proteins to the overall extraction of sediment-bound inorganic mercury (Hg) by gut fluids collected from deposit-feeding sipunculans and sea cucumbers were evaluated. The organic content and the Hg concentration in the sediment were modified to investigate their effects on Hg extraction. Cysteine was the key free amino acid in complexing Hg while proteins in the gut fluids also contributed significantly to the extraction. Different size fractions of gut fluids had different bindings with Hg at different Hg concentrations. Hg first bound with the < 10 kD and 50-100 kD fractions and then with the > 100 kD fraction when the Hg concentration was increased. Removing the organic matter (OM) from the sediments enhanced Hg extraction, indicating that competition for Hg binding between the strong binding sites in sediments (the organic matter) and gut fluids (cysteine) may control the extraction. However, Hg complexation with weak binding sites (e.g., Fe/Mn oxides) in sediments should not be ignored. We identified two sediment Hg pools with different mobilities based on Hg binding, which was influenced by the Hg concentration in the sediment and the ratio of binding sites between gut fluids and sediments. Our results help to explain the variations in gut fluid extraction and Hg bioaccumulation in different marine deposit feeders. © 2006 American Chemical Society.