HW7-2010_NACs_Case_plus articles[1]

HW7-2010_NACs_Case_plus articles[1] - AGRY 544 Reading and...

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AGRY 544 Reading and In Class Group Exercise (Homework #7) For: Monday 04/12/10 CASE STUDY: Sorption of Nitroaromatics to clay minerals: Trends and Mechanisms BEFORE CLASS on Monday 04/12/10 READ: Paper A: Weissmahr et al. (1999) EST 33:2593-2600 Paper B: Johnston et al. (2001) EST 35:4767-4772 Briefly record (bullet format is fine) on a separate piece(s) of paper the following information to prepare for Monday’s group discussions. 1. Briefly summarize key observations reported in each article. 2. State proposed mechanism in each article, followed by supporting information given by the authors of each. 3. Identify the similar information provided by both authors to support different proposed mechanisms. 4. What additional experiments would be helpful in differentiating between the 2 proposed mechanisms for the effect of cation type on sorption of the nitrobenzenes. 5. Additional review comments not covered above? During Monday’s class (1) As a group, discuss your responses to items #1-5 and be prepared to share your observations with the class. (2) Also as a group, come to an agreement on which of the proposed mechanisms you feel is most likely the correct one. (3) Please list your group members below (one list per group):
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Laboratory and Field Scale Evaluation of Geochemical Controls on Groundwater Transport of Nitroaromatic Ammunition Residues KENNETH W. WEISSMAHR, ‡,§ MARKUS HILDENBRAND, ²,# RENE Ä P. SCHWARZENBACH, AND STEFAN B. HADERLEIN* ,‡ Swiss Federal Institute for Environmental Science and Technology (EAWAG), Swiss Federal Institute of Technology (ETH), CH-8600 Du ¨bendorf, Switzerland, and Dresdner Grundwasserforschungszentrum e.V., Meraner Strasse 10, D-01217 Dresden, Germany Sorption to soils and sediments of nitroaromatic explosives may be due to interactions with natural organic matter (NOM) or complex formation with clays, which strongly depends on the type of exchangeable cations, i.e., the base saturation of the clays. We examined the relative importance of these two processes for NAC sorption at aquifer material and evaluated the potential of decreasing or enhancing the mobility of NACs in contaminated aquifers by stimulated cation exchange. Generally, sorption on NOM of 2,4,6-trinitrotoluene (TNT) and related nitroaromatic compounds (NACs) was low compared to sorption at clays, and no evidence for specific interactions with NOM was found. Adsorbed NOM hardly affected the complex formation of NACs with clays. NAC sorption at pure clays and at aquifer material depended on the K + - saturation of these materials. Typical aquifer material containing e 1% NOM and 3 - 5% clays exhibited similar sorption features than pure clay minerals, suggesting that NAC sorption to the bulk aquifer matrix was dominated by complex formation at clays. We applied these laboratory findings to a two-step field test designed to control the groundwater transport of NACs by the injection of electrolytes.
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This note was uploaded on 08/28/2011 for the course ESE 544 taught by Professor Lee during the Fall '11 term at Purdue University-West Lafayette.

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HW7-2010_NACs_Case_plus articles[1] - AGRY 544 Reading and...

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