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    <title>DRS Collection: Chemical Sciences</title>
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      <title>Sources of hydrocarbons in sediments of the Mandovi estuary and the Marmugoa harbour, west coast of India</title>
      <link>http://drs.nio.org/drs/handle/2264/1468</link>
      <description>Title: Sources of hydrocarbons in sediments of the Mandovi estuary and the Marmugoa harbour, west coast of India
&lt;br/&gt;
&lt;br/&gt;Authors: Harji, R.R.; Yvenat, A.; Bhosle, N.B.
&lt;br/&gt;
&lt;br/&gt;Abstract: Surface sediments were collected from various locations of the Mandovi estuary and the Marmugoa harbour, Goa, India. Sediments were analysed for organic carbon (OC), total lipids, n-alkanes concentration and composition. Concentrations of OC, total lipids and n-alkanes varied spatially and ranged from 1 to 2.5%, 176 to 1413 mu g/g dry weight (dw) sediments, and 0.8 to 3.2 mu g/g dw sediments of the Mandovi estuary, respectively; and from 0.6 to 2.9%, 233 to 1448 mu g/g dw sediments, and 1.6 to 10.7 mu g/g dw sediments in the Marmugoa harbour, respectively. Long chain, odd carbon n-alkanes (C23ûC33) in the Mandovi estuary, whereas short chain, even carbon n-alkanes (C sub(11)-C sub(21)) in the Marmugoa harbour sediments were more abundant. The total HC concentrations, n-alkane composition, CPI, UCM and other evaluation indices suggest the dominance of terrestrial hydrocarbons in the estuarine while petroleum derived hydrocarbons in the harbour sediments. This conclusion was further supported by the abundance of hopanes with C sub(29) to C sub(34) alpha, beta compounds and steranes with C sub(27), C sub(28) and C sub(29) compounds in the harbour sediments</description>
      <pubDate>Mon, 29 Oct 2007 22:58:59 GMT</pubDate>
    </item>
    <item>
      <title>Sulfur cycle</title>
      <link>http://drs.nio.org/drs/handle/2264/1462</link>
      <description>Title: Sulfur cycle
&lt;br/&gt;
&lt;br/&gt;Authors: LokaBharathi, P.A.
&lt;br/&gt;
&lt;br/&gt;Abstract: Microbes, especially bacteria, play an important role in oxidative and reductive cycle of sulfur. The oxidative part of the cycle is mediated by photosynthetic bacteria in the presence of light energy and chemosynthetic forms in the absence of light energy. At the end of the anaerobic food chain in bacteria they serve to purify the system of sulfide and other metabolic end products. In the process sulfur is returned to the system as sulfate. In transition zones from anaerobic to aerobic, photosynthetic bacteria can form a food source to protozoans and microzooplankton. Chemosynthetic sulfur-oxidizing bacteria are the dominant bacterial forms that support thriving ecosystems in hydrothermal vents. Scientists are seeking evidences from such extreme environment for similar life on other planetary bodies. The reductive cycle on the other hand is mostly driven by the sulfate/sulfur-reducing bacteria which use sulfate as the electron acceptor in anaerobic respiration to produce sulfide. Their close association with other microbes can have profound geochemical influence. Their metabolic activity dictates the availability of trace metals to other forms of life. While sulfide gets precipitated, phosphate gets released into the systems. Nitrogen fixation by these anaerobes also adds to the nitrogen economy of the environment they inhabit. In sediments of continental shelves that hold the reserve of gas hydrates, these microbes can modulate the concentration of methane in such ecosystems. Most importantly, the interaction with DMSP, an osmolyte from phytoplankton, can have wideranging climatic implications. The main reactions of the sulfur cycle involving living organisms are closely related to the carbon cycle. The amount of carbon involved in the fluxes of the sulfur cycle through biogenic processes varies depending on the type of organisms undertaking the metabolism of the sulfur compounds. The estimates suggest that the anthropogenic sulfur fluxes to the atmosphere and hydrosphere have reached a level comparable with that of natural fluxes. The natural sulfur flux from the lithosphere, its main reservoir, is compensated by the reverse flux of sulfur compounds to the lithospheric sediments of the ocean. Further, there is also indication that by the end of this century the anthropogenic sulfur fluxes could notably increase all over the world.</description>
      <pubDate>Mon, 29 Oct 2007 22:58:59 GMT</pubDate>
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    <item>
      <title>Post depositional memory record of mercury in sediment near effluent disposal site of a chlor-alkali plant in Thane Creek-Mumbai Harbour, India</title>
      <link>http://drs.nio.org/drs/handle/2264/1454</link>
      <description>Title: Post depositional memory record of mercury in sediment near effluent disposal site of a chlor-alkali plant in Thane Creek-Mumbai Harbour, India
&lt;br/&gt;
&lt;br/&gt;Authors: Jaiswar, A.R.S.; Rokadel, M.A.; Zingde, M.D.; Borole, D.V.
&lt;br/&gt;
&lt;br/&gt;Abstract: A mercury-cell chlor-alkali plant operating at Airoli (eastern bank of Thane Creek) for&#xD;
40 years, caused widespread 'contamination of the surrounding environment. Untreated wastewater from the plant was discharged to Thane Creek for several years. Thane Creek joins to Ulhas Estuary, an impacted estuary by mercury (Hg) released by several industries including two chloralkali&#xD;
industries by a narrow ann and opens to Arabian Sea through Mumbai Harbour. In order to understand historical record of anthropogenic Hg and its association to AI, Fe and total organic carbon (TOC), estimation of Hg, AI, Fe and TOC was made in surface sediments and cores from&#xD;
Thane Creek-Mumbai Harbour (Bay) and the adjacent -coastal area. Though 70 % of the plant has been changed to membrane-cell based technology, surficial sediment in the vicinity of effluent release contain high concentration (upto 1.19mu g g-1 d. w.) of Hg as compared to its background&#xD;
value (0.10 mu g g-1 d. w.). The contaminated creek sediments are prone to current-driven resuspension and are acting as a strong source of Hg to the sediment of coastal region. Several rocks and sediments from the catchment area were analyzed to find out natural background of Hg.&#xD;
Lithogenic and anthropogenic Hg buried in marine sediments is quantified based on normalization with AI, Fe and TOC and inter-comparisons of results indicate comparable values obtained by using Al and Fe while discernible deviations are found when calculated by using TOe. The Hg profile in&#xD;
core from the effluent release site for which sedimentation rate has been established, is discussed in terms of progressive removal of Hg from the effluent after mid-1970s and partial changeover of the&#xD;
manufacturing process from Hg cell to membrane cell production subsequent to 1992. Based on reported sedimentation rate in the locality, maximum concentration (49.l9 mu g g-1 d. w.) of Hg represents the year 1967, when the chlor-alkali plant started discharging its untreated effluent to the&#xD;
creek. Results indicate that more than 80 % of Hg settles in the vicinity of its discharge and once deposited in the sediment, it is not affected to any substantial degree by diagenesis</description>
      <pubDate>Mon, 29 Oct 2007 22:58:59 GMT</pubDate>
    </item>
    <item>
      <title>Mercury and lead tolerance in hypersaline sulfate-reducing bacteria</title>
      <link>http://drs.nio.org/drs/handle/2264/1422</link>
      <description>Title: Mercury and lead tolerance in hypersaline sulfate-reducing bacteria
&lt;br/&gt;
&lt;br/&gt;Authors: Harithsa, S.; Kerkar, S.; LokaBharathi, P.A.
&lt;br/&gt;
&lt;br/&gt;Abstract: Sulfate-reducing bacteria (SRB) HSR 1, HSR 4, and HSR 14 isolated from the salt pans of Goa, India grew best at 90-100 ppt salinity on substrates like formate, acetate, lactate, butyrate, ethanol and benzoate. They were gram negative, non-sporulating, non-motile rods lacking in desulfoviridin and cytochromes. Examination of these isolates for heavy metal tolerance and response studies in terms of growth and sulfate-reducing activity (SRA) were carried out using HgCl sub(2) and Pb(NO sub(3)) sub(2) at final concentration of 50, 100, and 200 and 100, 200 and 500 mu g ml sup(-1) respectively. With Hg, HSR 1 showed approx. 80% of the control's growth at 100 and 200 mu g ml sup(-1) but SRA reached only 60% of the control values at the end of 14 days. HSR 14 could reach is greater than 100% of the control's growth at 200 mu g ml sup(-1) but the SRA reached only up to 60% of the control without metal at 100 mu g ml sup(-1). Though the concentration of Pb was double that of Hg, HSR4 could grow and respire better than the control, the growth being stimulated by 160% and respiration by 170% in the presence of 500 mu g ml sup(-1) of Pb (NO sub(3)) sub(2). It is probable that some hypersaline SRB are more tolerant to heavy metals than the mesohaline counterparts and could be more effectively used for precipitating these metals in bioremediatory measures. Further examination of their responses to varied concentration of metals under different salinities would indicate their range of applicability.</description>
      <pubDate>Mon, 29 Oct 2001 22:58:59 GMT</pubDate>
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