Copyright (c) 2011 All rights reserved. http://works.bepress.com/mark_rudin Recent documents in Mark J. Rudin en-us Sat, 06 Aug 2011 02:07:32 PDT 3600 http://works.bepress.com/mark_rudin/5 http://works.bepress.com/mark_rudin/5 Thu, 04 Aug 2011 14:30:44 PDT The distribution of lignin in sediment is a useful tool for tracing the transport of land-derived organic matter in an aquatic environment. Tetramethylammonium hydroxide (TMAH) flash chemopyrolysis, or chemolysis followed by GC-MS analysis can be used for evaluating the origin of organic carbon in sediments. TMAH chemopyrolysis or chemolysis of organic matter produces a myriad of semi-volatile products. Among these products are methylated phenols which are an indirect measure of lignin in sediment. In this study, total organic carbon, elemental carbon, and lignin were measured in Lake Mead sediments. This study indicates that terrestrial runoff makes a contribution to Lake Mead sediments, and that this contribution is most apparent in sediment that is close to the Las Vegas Wash. Two chemolysis methods (on-line and off-line) were examined and compared for detection of lignin phenols. The results from these sediment cores indicate that comparable results can be obtained from the two approaches, although detection levels are significantly lower for the off-line approach.

]]> Spencer M. Steinberg et al. http://works.bepress.com/mark_rudin/4 http://works.bepress.com/mark_rudin/4 Thu, 04 Aug 2011 14:23:01 PDT Iodine-129 is a fission product and highly mobile in the environment. Along with other stable isotopes of iodine, 129I is released during reprocessing of nuclear fuel and must be trapped to prevent the release of radioactivity to the environment. Past studies have provided evidence that iodine can become associated with natural organic matter (NOM). This research explores the use of NOM (sphagnum peat and humic acid) to sequester iodine from the vapor and aqueous phases. NOM-associated iodine may be stable for geological storage. NOM-sequestered iodine can be recovered by pyrolysis to prepare target materials for transmutation. The nature of the NOM-iodine association has been explored.

]]> S. M. Steinberg et al. http://works.bepress.com/mark_rudin/3 http://works.bepress.com/mark_rudin/3 Thu, 04 Aug 2011 14:15:29 PDT Previous studies have shown that iodine (including 129I) can be strongly retained in organic-rich surface soils and sediment and that a large fraction of soluble iodine may be associated with dissolved humic material. Iodate (IO3 –) reacts with natural organic matter (NOM) producing either hypoiodous acid (HIO) or I2 as an intermediate. This intermediate is subsequently incorporated into the organic matter. Based on reactions of model compounds, we infer that iodine reacts with peat by aromatic substitution of hydrogen on phenolic constituents of the peat. Alternatively, the intermediate, HIO or I2, may be reduced to iodide (I–). The pH (and temperature) dependence of the IO3 – reaction (reduction) has been explored with sphagnum peat, alkali lignin, and several model compounds. The incorporation of iodine into NOM has been verified by pyrolysis gas chromatography/mass spectrometry (GC/MS). Model compound studies indicate that reduction of IO3 – to HIO may result from reaction with hydroquinone (or semiquinone) moieties of the peat.

]]> S. M. Steinberg et al. http://works.bepress.com/mark_rudin/1 http://works.bepress.com/mark_rudin/1 Mon, 18 May 2009 14:53:49 PDT Lake Mead, USA serves as an excellent field laboratory for studying a number of environmental processes, including the distribution and rate of sediment deposition, the bioavailability of anthropogenic contaminants in water and sediment columns, and the impact of naturally-occurring events such as fires and floods on lake ecosystems. Attempts at understanding this body of water, critical to the viability of over 20 million people, requires expertise and experience across a substantial number of disciplines. A research team comprised of representatives from academia and several federal agencies collected lakefloor side-scan sonar and seismic reflection measurements, along with sediment cores, in various parts of Lake Mead to begin our understanding of sedimentation processes in this dynamic reservoir. Preliminary results of the work are presented along with lessons learned in assembling this truly interdisciplinary team. The principal investigator on this project will also discuss how and why this spirit of collaborative research exists today at Boise State University.

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