Inhibition of precipitation and aggregation of metacinnabar (mercuric sulfide) by dissolved organic matter isolated from the Florida Everglades

Environmental Science & Technology
By: , and 

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Abstract

Precipitation and aggregation of metacinnabar (black HgS) was inhibited in the presence of low concentrations (≥3 mg C/L) of humic fractions of dissolved organic matter (DOM) isolated from the Florida Everglades. At low Hg concentrations (≤5 × 10-8 M), DOM prevented the precipitation of metacinnabar. At moderate Hg concentrations (5 × 10-5 M), DOM inhibited the aggregation of colloidal metacinnabar (Hg passed through a 0.1 μm filter but was removed by centrifugation). At Hg concentrations greater than 5 × 10-4 M, mercury formed solid metacinnabar particles that were removed from solution by a 0.1 μm filter. Organic matter rich in aromatic moieties was preferentially removed with the solid. Hydrophobic organic acids (humic and fulvic acids) inhibited aggregation better than hydrophilic organic acids. The presence of chloride, acetate, salicylate, EDTA, and cysteine did not inhibit the precipitation or aggregation of metacinnabar. Calcium enhanced metacinnabar aggregation even in the presence of DOM, but the magnitude of the effect was dependent on the concentrations of DOM, Hg, and Ca. Inhibition of metacinnabar precipitation appears to be a result of strong DOM-Hg binding. Prevention of aggregation of colloidal particles appears to be caused by adsorption of DOM and electrostatic repulsion.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Inhibition of precipitation and aggregation of metacinnabar (mercuric sulfide) by dissolved organic matter isolated from the Florida Everglades
Series title Environmental Science & Technology
DOI 10.1021/es9811187
Volume 33
Issue 9
Year Published 1999
Language English
Publisher ACS
Contributing office(s) Toxic Substances Hydrology Program
Description 8 p.
First page 1418
Last page 1423
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