<?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>P. V. Winger</dc:contributor>
  <dc:contributor>K. J. Bogenrieder</dc:contributor>
  <dc:creator>P. J. Lasier</dc:creator>
  <dc:date>2000</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;Manganese is a toxic element frequently overlooked when assessing toxicity of effluents, sediments, and pore waters. Manganese can be present at toxic levels in anoxic solutions due to increased solubility under chemically reducing conditions, and it can remain at those levels for days in aerated test waters due to slow precipitation kinetics.&amp;nbsp;&lt;/span&gt;&lt;i&gt;Ceriodaphnia dubia&lt;/i&gt;&lt;span&gt;&amp;nbsp;and&amp;nbsp;&lt;/span&gt;&lt;i&gt;Hyalella azteca&lt;/i&gt;&lt;span&gt;&amp;nbsp;are freshwater organisms often used for toxicity testing and recommended for assessments of effluents and pore waters. Lethal and reproductive-inhibition concentrations of Mn were determined for&amp;nbsp;&lt;/span&gt;&lt;i&gt;C. dubia&lt;/i&gt;&lt;span&gt;&amp;nbsp;in acute 48-h tests and chronic three-brood tests using animals &amp;lt;24 h old and between 24 and 48 h old. Sensitivity of&amp;nbsp;&lt;/span&gt;&lt;i&gt;H. azteca&lt;/i&gt;&lt;span&gt;&amp;nbsp;to Mn was determined with 7-day-old animals in acute 96-h tests. Tests were run at three levels of water hardness to assess the amelioratory effect, which was often significant. Manganese concentrations were measured analytically at test initiation and after 96 h for calculation of toxicity and determination of Mn precipitation during the tests. Minimal amounts of Mn (≤3%) precipitated within 96 h. LC&lt;/span&gt;&lt;sub&gt;50&lt;/sub&gt;&lt;span&gt;s determined for&amp;nbsp;&lt;/span&gt;&lt;i&gt;H. azteca&lt;/i&gt;&lt;span&gt;&amp;nbsp;progressively increased from 3.0 to 8.6 to 13.7 mg Mn/L in soft, moderately hard, and hard waters, respectively. The tolerance of&amp;nbsp;&lt;/span&gt;&lt;i&gt;C. dubia&lt;/i&gt;&lt;span&gt;&amp;nbsp;to Mn was not significantly different between moderately hard and hard waters, but was significantly lower in soft water. Manganese sensitivity of&amp;nbsp;&lt;/span&gt;&lt;i&gt;C. dubia&lt;/i&gt;&lt;span&gt;&amp;nbsp;was not significantly different between the ages tested. Acute LC&lt;/span&gt;&lt;sub&gt;50&lt;/sub&gt;&lt;span&gt;&amp;nbsp;values for&amp;nbsp;&lt;/span&gt;&lt;i&gt;C. dubia&lt;/i&gt;&lt;span&gt;&amp;nbsp;averaged 6.2, 14.5 and 15.2 mg Mn/L and chronic IC&lt;/span&gt;&lt;sub&gt;50&lt;/sub&gt;&lt;span&gt;&amp;nbsp;values averaged 3.9, 8.5 and 11.5 mg Mn/L for soft, moderately-hard and hard waters, respectively. Manganese toxicity should be considered when assessing solutions with concentrations approaching these levels.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1007/s002449910039</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Springer</dc:publisher>
  <dc:title>Toxicity of manganese to Ceriodaphnia dubia and Hyalella azteca</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>