scholarly journals Zinc Geochemical Cycling in a Phosphorus‐Rich Ocean During the Early Ediacaran

2018 ◽  
Vol 123 (8) ◽  
pp. 5248-5260 ◽  
Author(s):  
Haifeng Fan ◽  
Hanjie Wen ◽  
Chaoyi Xiao ◽  
Ting Zhou ◽  
Christophe Cloquet ◽  
...  
Keyword(s):  
Geochemical Cycling

Illite-smectites and the influence of burial diagenesis on the geochemical cycling of nitrogen

Clay Minerals ◽  
1998 ◽  
Vol 33 (4) ◽  
pp. 539-546 ◽  
Author(s):  
P. A. Schroeder ◽  
A. A. McLain
Keyword(s):  
Reaction Mechanisms ◽  
Ostwald Ripening ◽  
Precipitation Reaction ◽  
Oil Well ◽  
Burial Diagenesis ◽  
Fixed Nitrogen ◽  
Geochemical Cycling ◽  
Oil Generation ◽  
Fraction Increase ◽  
Changing Rate

AbstractFixed nitrogen in illite-smectites (I-S) has been measured for Miocene shales from a Gulf of Mexico oil well. Fixed N values for the <0.2 µm fraction increase with depth from 150 ppm (1000 m) to a maximum of 360 ppm (3841 m). This increase is coincident with illitization from 41% I in I-S to 75% I in I-S. Below 3841 m, fixed N values decrease to 190 ppm (4116 m) while I-S is maintained with a slight increase from 77 to 82%. The changes in fixed N with increasing illitization are consistent with the notion that illitization proceeds via both transformation and dissolution/ precipitation reaction mechanisms. The trend of decreasing fixed N in illitic I-S is compatible with surface-controlled crystal growth and Ostwald ripening mechanisms for illitization. The trend may also be linked to the timing of maximum NH] release from kerogen maturation during oil generation. The changing rate of NH+4 liberation from organic matter and multiple illitization reaction mechanisms can result in complex N geochemical cycling pathways throughout early diagenesis to metamorphism.

scholarly journals Substrate-dependent competition and cooperation relationships between Geobacter and Dehalococcoides for their organohalide respiration

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Yongyi Liang ◽  
Qihong Lu ◽  
Zhiwei Liang ◽  
Xiaokun Liu ◽  
Wenwen Fang ◽  
...  
Keyword(s):  
Electron Donors ◽  
Community Stability ◽  
Organohalide Respiration ◽  
Competition And Cooperation ◽  
Free Competition ◽  
Isolation And Characterization ◽  
Geochemical Cycling ◽  
New Strategy ◽  
Insight Into

AbstractObligate and non-obligate organohalide-respiring bacteria (OHRB) play central roles in the geochemical cycling and environmental bioremediation of organohalides. Their coexistence and interactions may provide functional redundancy and community stability to assure organohalide respiration efficiency but, at the same time, complicate isolation and characterization of specific OHRB. Here, we employed a growth rate/yield tradeoff strategy to enrich and isolate a rare non-obligate tetrachloroethene (PCE)-respiring Geobacter from a Dehalococcoides-predominant microcosm, providing experimental evidence for the rate/yield tradeoff theory in population selection. Surprisingly, further physiological and genomic characterizations, together with co-culture experiments, revealed three unique interactions (i.e., free competition, conditional competition and syntrophic cooperation) between Geobacter and Dehalococcoides for their respiration of PCE and polychlorinated biphenyls (PCBs), depending on both the feeding electron donors (acetate/H2 vs. propionate) and electron acceptors (PCE vs. PCBs). This study provides the first insight into substrate-dependent interactions between obligate and non-obligate OHRB, as well as a new strategy to isolate fastidious microorganisms, for better understanding of the geochemical cycling and bioremediation of organohalides.

scholarly journals Iron Requirement for Mn(II) Oxidation by Leptothrix discophora SS-1

2008 ◽  
Vol 75 (5) ◽  
pp. 1229-1235 ◽  
Author(s):  
Iman A. El Gheriany ◽  
Daniela Bocioaga ◽  
Anthony G. Hay ◽  
William C. Ghiorse ◽  
Michael L. Shuler ◽  
...  
Keyword(s):  
Complex Formation ◽  
Temporal Variations ◽  
Iron Limitation ◽  
Gene Transcript ◽  
Cellular Functions ◽  
Transcript Levels ◽  
Leptothrix Discophora ◽  
Geochemical Cycling ◽  
Iron Requirement

ABSTRACT A common form of biocatalysis of Mn(II) oxidation results in the formation of biogenic Mn(III, IV) oxides and is a key reaction in the geochemical cycling of Mn. In this study, we grew the model Mn(II)-oxidizing bacterium Leptothrix discophora SS-1 in media with limited iron (0.1 μM iron/5.8 mM pyruvate) and sufficient iron (0.2 μM iron/5.8 mM pyruvate). The influence of iron on the rate of extracellular Mn(II) oxidation was evaluated. Cultures in which cell growth was limited by iron exhibited reduced abilities to oxidize Mn(II) compared to cultures in medium with sufficient iron. While the extracellular Mn(II)-oxidizing factor (MOF) is thought to be a putative multicopper oxidase, Mn(II) oxidation in the presence of zero added Cu(II) was detected and the decrease in the observed Mn(II) oxidation rate in iron-limited cultures was not relieved when the medium was supplemented with Cu(II). The decline of Mn(II) oxidation under iron-limited conditions was not accompanied by siderophore production and is unlikely to be an artifact of siderophore complex formation with Mn(III). The temporal variations in mofA gene transcript levels under conditions of limited and abundant iron were similar, indicating that iron limitation did not interfere with the transcription of the mofA gene. Our quantitative PCR results provide a step forward in understanding the regulation of Mn(II) oxidation. The mechanistic role of iron in Mn(II) oxidation is uncertain; the data are consistent with a direct requirement for iron as a component of the MOF or an indirect effect of iron resulting from the limitation of one of many cellular functions requiring iron.

scholarly journals Insights on geochemical cycling of U, Re and Mo from seasonal sampling in Boston Harbor, Massachusetts, USA

2007 ◽  
Vol 71 (4) ◽  
pp. 895-917 ◽  
Author(s):  
Jennifer L. Morford ◽  
William R. Martin ◽  
Linda H. Kalnejais ◽  
Roger François ◽  
Michael Bothner ◽  
...  
Keyword(s):  
Boston Harbor ◽  
Geochemical Cycling

The geochemical cycling of trace elements in a biogenic meromictic lake

1994 ◽  
Vol 58 (19) ◽  
pp. 3993-4008 ◽  
Author(s):  
Laurie S. Balistrieri ◽  
James W. Murray ◽  
Barbara Paul
Keyword(s):  
Trace Elements ◽  
Meromictic Lake ◽  
Geochemical Cycling

Geochemical cycling in the Hooghly estuary, India

2002 ◽  
Vol 79 (3-4) ◽  
pp. 171-183 ◽  
Author(s):  
B.L.K. Somayajulu ◽  
R. Rengarajan ◽  
R.A. Jani
Keyword(s):  
Hooghly Estuary ◽  
Geochemical Cycling

scholarly journals Geochemical Cycling of Iodine Species in Soils

2009 ◽  
pp. 93-105 ◽  
Author(s):  
Qinhong Hu ◽  
Jean E. Moran ◽  
Van Blackwood
Keyword(s):  
Iodine Species ◽  
Geochemical Cycling

Molecular geomicrobiology: genes and geochemical cycling

2003 ◽  
Vol 209 (1-2) ◽  
pp. 1-17 ◽  
Author(s):  
Jennifer Macalady ◽  
Jillian F Banfield
Keyword(s):  
Geochemical Cycling
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