Zierenberg Robert

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Zierenberg
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Robert
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  • Article
    Biogeochemical exploration of the Pescardero Basin vents
    (The Oceanography Society, 2018-03) Michel, Anna P. M. ; Wankel, Scott D. ; Beaulieu, Stace E. ; Soule, Samuel A. ; Mullineaux, Lauren S. ; Coleman, Dwight ; Escobar Briones, Elva ; Gaytan-Caballero, Adriana ; McDermott, Jill M. ; Mills, Susan W. ; Speth, Dan ; Zierenberg, Robert
  • Article
    Mercury and monomethylmercury in fluids from Sea Cliff submarine hydrothermal field, Gorda Ridge
    (American Geophysical Union, 2006-09-09) Lamborg, Carl H. ; Von Damm, Karen L. ; Fitzgerald, William F. ; Hammerschmidt, Chad R. ; Zierenberg, Robert
    Submarine hydrothermal systems are hypothesized to be a potentially important source of monomethylmercury (MMHg) to the ocean, yet the amount of MMHg in vent fluids is unknown. Here, we report total Hg and MMHg concentrations in hydrothermal vent fluids sampled from the Sea Cliff site on the Gorda Ridge. MMHg is the dominant Hg species, and levels of total Hg are enhanced slightly compared to seawater. Hg is enriched in deposits surrounding the site, suggesting near-field deposition from fluid plumes, with rapid MMHg demethylation and scavenging of Hg(II) complexes. Assuming the flux of MMHg from Sea Cliff is representative of global submarine hydrothermal inputs, we estimate a flux of 0.1–0.4 Mmoles y−1, which may be attenuated by scavenging near the vents. However, deep waters are not typically known to be elevated in Hg, and thus we suggest that hydrothermal systems are not significant sources of MMHg to commercial fisheries.
  • Article
    Correction to “Mercury and monomethylmercury in fluids from Sea Cliff submarine hydrothermal field, Gorda Ridge”
    (American Geophysical Union, 2007-01-18) Lamborg, Carl H. ; Von Damm, Karen L. ; Fitzgerald, William F. ; Hammerschmidt, Chad R. ; Zierenberg, Robert
  • Article
    Vailulu'u Seamount, Samoa : life and death on an active submarine volcano
    (National Academy of Sciences, 2006-04-13) Staudigel, Hubert ; Hart, Stanley R. ; Pile, Adele ; Bailey, Bradley E. ; Baker, Edward T. ; Brooke, Sandra ; Connelly, Douglas P. ; Haucke, Lisa ; German, Christopher R. ; Hudson, Ian ; Jones, Daniel O. B. ; Koppers, Anthony A. P. ; Konter, Jasper G. ; Lee, Ray ; Pietsch, Theodore W. ; Tebo, Bradley M. ; Templeton, Alexis S. ; Zierenberg, Robert ; Young, Craig M.
    Submersible exploration of the Samoan hotspot revealed a new, 300-m-tall, volcanic cone, named Nafanua, in the summit crater of Vailulu'u seamount. Nafanua grew from the 1,000-m-deep crater floor in <4 years and could reach the sea surface within decades. Vents fill Vailulu'u crater with a thick suspension of particulates and apparently toxic fluids that mix with seawater entering from the crater breaches. Low-temperature vents form Fe oxide chimneys in many locations and up to 1-m-thick layers of hydrothermal Fe floc on Nafanua. High-temperature (81°C) hydrothermal vents in the northern moat (945-m water depth) produce acidic fluids (pH 2.7) with rising droplets of (probably) liquid CO2. The Nafanua summit vent area is inhabited by a thriving population of eels (Dysommina rugosa) that feed on midwater shrimp probably concentrated by anticyclonic currents at the volcano summit and rim. The moat and crater floor around the new volcano are littered with dead metazoans that apparently died from exposure to hydrothermal emissions. Acid-tolerant polychaetes (Polynoidae) live in this environment, apparently feeding on bacteria from decaying fish carcasses. Vailulu'u is an unpredictable and very active underwater volcano presenting a potential long-term volcanic hazard. Although eels thrive in hydrothermal vents at the summit of Nafanua, venting elsewhere in the crater causes mass mortality. Paradoxically, the same anticyclonic currents that deliver food to the eels may also concentrate a wide variety of nektonic animals in a death trap of toxic hydrothermal fluids.