scispace - formally typeset
Search or ask a question
Author

Doug Hammond

Bio: Doug Hammond is an academic researcher from University of Southern California. The author has contributed to research in topics: Anoxic waters & Total organic carbon. The author has an hindex of 2, co-authored 2 publications receiving 2874 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: Pore water profiles of total CO 2, pH, PO 3−4, NO − 3 plus NO − 2, SO 2− 4, S 2−, Fe 2+ and Mn 2+ have been obtained in cores from pelagic sediments of the eastern equatorial Atlantic under waters of moderate to high productivity as mentioned in this paper.

3,045 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: In this paper, a synthesis of the use of selected trace elements as proxies for reconstruction of paleoproductivity and paleoredox conditions is presented, and the combined used of U, V and Mo enrichments may allow suboxic environments to be distinguished from anoxic-euxinic ones.

2,708 citations

Journal ArticleDOI
TL;DR: The physiological characteristics of Geobacter species appear to explain why they have consistently been found to be the predominant Fe(III)- and Mn(IV)-reducing microorganisms in a variety of sedimentary environments.

2,633 citations

Journal ArticleDOI
TL;DR: This is the first demonstration that microorganisms can completely oxidize organic compounds with Fe(III) or Mn(IV) as the sole electron acceptor and that oxidation of organic matter coupled to dissimilatory Fe( III), Mn( IV), or Mn (IV) reduction can yield energy for microbial growth.
Abstract: A dissimilatory Fe(III)- and Mn(IV)-reducing microorganism was isolated from freshwater sediments of the Potomac River, Maryland. The isolate, designated GS-15, grew in defined anaerobic medium with acetate as the sole electron donor and Fe(III), Mn(IV), or nitrate as the sole electron acceptor. GS-15 oxidized acetate to carbon dioxide with the concomitant reduction of amorphic Fe(III) oxide to magnetite (Fe(3)O(4)). When Fe(III) citrate replaced amorphic Fe(III) oxide as the electron acceptor, GS-15 grew faster and reduced all of the added Fe(III) to Fe(II). GS-15 reduced a natural amorphic Fe(III) oxide but did not significantly reduce highly crystalline Fe(III) forms. Fe(III) was reduced optimally at pH 6.7 to 7 and at 30 to 35 degrees C. Ethanol, butyrate, and propionate could also serve as electron donors for Fe(III) reduction. A variety of other organic compounds and hydrogen could not. MnO(2) was completely reduced to Mn(II), which precipitated as rhodochrosite (MnCO(3)). Nitrate was reduced to ammonia. Oxygen could not serve as an electron acceptor, and it inhibited growth with the other electron acceptors. This is the first demonstration that microorganisms can completely oxidize organic compounds with Fe(III) or Mn(IV) as the sole electron acceptor and that oxidation of organic matter coupled to dissimilatory Fe(III) or Mn(IV) reduction can yield energy for microbial growth. GS-15 provides a model for how enzymatically catalyzed reactions can be quantitatively significant mechanisms for the reduction of iron and manganese in anaerobic environments.

2,233 citations

MonographDOI
16 Dec 2004
TL;DR: The second edition of The Biomarker Guide as mentioned in this paper provides a comprehensive account of the role that biomarker technology plays both in petroleum exploration and in understanding Earth history and processes.
Abstract: The second edition of The Biomarker Guide is a fully updated and expanded version of this essential reference. Now in two volumes, it provides a comprehensive account of the role that biomarker technology plays both in petroleum exploration and in understanding Earth history and processes. Biomarkers and Isotopes in the Environment and Human History details the origins of biomarkers and introduces basic chemical principles relevant to their study. It discusses analytical techniques, and applications of biomarkers to environmental and archaeological problems. The Biomarker Guide is an invaluable resource for geologists, petroleum geochemists, biogeochemists, environmental scientists and archaeologists.

2,163 citations

Journal ArticleDOI
TL;DR: In this article, the organic matter content of sediments is inferred from bulk properties such as elemental compositions, carbon and nitrogen stable isotope ratios, Rock-Eval pyrolysis data, and organic petrography.

1,947 citations