<?xml version='1.0' encoding='utf-8'?>
<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>George R. Aiken</dc:contributor>
  <dc:contributor>Cynthia Gilmour</dc:contributor>
  <dc:creator>Andrew M. Graham</dc:creator>
  <dc:date>2013</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Dissolved organic matter (DOM) is a key component of fate and transport models for most metals, including mercury (Hg). Utilizing a suite of diverse DOM isolates, we demonstrated that DOM character, in addition to concentration, influences inorganic Hg (Hg(II)&lt;/span&gt;&lt;sub&gt;i&lt;/sub&gt;&lt;span&gt;) bioavailability to Hg-methylating bacteria. Using a model Hg-methylating bacterium,&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;Desulfovibrio desulfuricans&lt;/i&gt;&lt;span&gt;ND132, we evaluated Hg-DOM-sulfide bioavailability in washed-cell assays at environmentally relevant Hg/DOM ratios (∼1–8 ng Hg/mg C) and sulfide concentrations (1–1000 μM). All tested DOM isolates significantly enhanced Hg methylation above DOM-free controls (from ∼2 to &amp;gt;20-fold for 20 mg C/L DOM solutions), but high molecular weight/highly aromatic DOM isolates and/or those with high sulfur content were particularly effective at enhancing Hg methylation. Because these experiments were conducted under conditions of predicted supersaturation with respect to metacinnabar (β-HgS(s)), we attribute the DOM-dependent enhancement of Hg(II)&lt;/span&gt;&lt;sub&gt;i&lt;/sub&gt;&lt;span&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;bioavailability to steric and specific chemical (e.g., DOM thiols) inhibition of β-HgS(s) growth and aggregation by DOM. Experiments examining the role of DOM across a wide sulfide gradient revealed that DOM only enhances Hg methylation under fairly low sulfide conditions (≲30 μM), conditions that favor HgS nanoparticle/cluster formation relative to dissolved HgS species.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1021/es400414a</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>ACS</dc:publisher>
  <dc:title>Effect of dissolved organic matter source and character on microbial Hg methylation in Hg–S–DOM solutions</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>