Inorganic chemistry, gas compositions and dissolved organic carbon in fluids from sedimented young basaltic crust on the Juan de Fuca Ridge flanks

Lin, Hsiang Ju; Cowen, James P.; Olson, E. J.; Amend, Jan P.; Lilley, Marvin D.

doi:10.1016/j.gca.2012.02.017

Cited by 57 publications

(88 citation statements)

References 68 publications

(112 reference statements)

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“…Over the course of the study, the pumping system became better sealed from intruding seawater, permitting a steady increase in the borehole fluid temperature at which sampling began, and an increase in the volume of high-integrity borehole fluid samples. Instead of using a multi-day in situ filtration (Cowen et al, 2003), a clean pump was used here to fill large-volume sampling bags over the course of hours; this relatively rapid sampling method appears to have minimized the contaminating effects of surrounding seawater as evident by the collection of samples that appear to be of pristine ocean basement crustal fluid Lin et al, 2012). The evolution of cleaner sampling equipment and methodology are positive developments for the field of research and represent the best window available into the deep subsurface oceanic crust.…”

Section: Discussionmentioning

confidence: 99%

“…These geological features allow deep seawater to be entrained into the ocean basement and to evolve during its passage through the relatively warm and chemically reducing basement rock environment (Cowen, 2004). The biological and chemical characteristics of crustal fluids collected via CORK observatories tapping into basement fluid recharge zones likely reflect the response of the in situ basement microbial community to an influx of terminal electron acceptors (Wheat et al, 2010;Lin et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…Relatively inert stainless steel fluid delivery lines running exterior to the CORK casing are featured on a new generation of CORK observatories deployed on both pre-existing (1026B) and new (1301A) boreholes (Fisher et al, 2005b) in an effort to sample deeply buried basement fluids while controlling contamination and minimizing biofouling effects noted in previous studies (Cowen et al, 2003). In this study, a pump with titanium-and Teflon-wetted parts was used to draw basement fluids up the fluid delivery line and through the CORK spigot, permitting thorough flushing of the fluid delivery lines before the collection of basement fluids Lin et al, 2012). The upgraded materials and extensive flushing of the fluid delivery line facilitate high-integrity sampling of the crustal fluids, providing for an accurate assessment of in situ microbial community characteristics from the sedimentcovered basement rock of the ridge flanks.…”

Section: Introductionmentioning

confidence: 99%

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Microbial diversity within basement fluids of the sediment-buried Juan de Fuca Ridge flank

et al. 2012

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Despite its immense size, logistical and methodological constraints have largely limited microbiological investigations of the subseafloor basement biosphere. In this study, a unique sampling system was used to collect fluids from the subseafloor basaltic crust via a Circulation Obviation Retrofit Kit (CORK) observatory at Integrated Ocean Drilling Program borehole 1301A, located at a depth of 2667 m in the Pacific Ocean on the eastern flank of the Juan de Fuca Ridge. Here, a fluid delivery line directly accesses a 3.5 million years old basalt-hosted basement aquifer, overlaid by 262 m of sediment, which serves as a barrier to direct exchange with bottom seawater. At an average of 1.2 × 104 cells ml−1, microorganisms in borehole fluids were nearly an order of magnitude less abundant than in surrounding bottom seawater. Ribosomal RNA genes were characterized from basement fluids, providing the first snapshots of microbial community structure using a high-integrity fluid delivery line. Interestingly, microbial communities retrieved from different CORKs (1026B and 1301A) nearly a decade apart shared major community members, consistent with hydrogeological connectivity. However, over three sampling years, the dominant gene clone lineage changed from relatives of Candidatus Desulforudis audaxviator within the bacterial phylum Firmicutes in 2008 to the Miscellaneous Crenarchaeotic Group in 2009 and a lineage within the JTB35 group of Gammaproteobacteria in 2010, and statistically significant variation in microbial community structure was observed. The enumeration of different phylogenetic groups of cells within borehole 1301A fluids supported our observation that the deep subsurface microbial community was temporally dynamic.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Microbial diversity within basement fluids of the sediment-buried Juan de Fuca Ridge flank

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“…Two processes, removal during hydrothermal circulation and adsorption onto sinking particles, have been identified as sinks for deep-sea refractory DOM. Hydrothermal fluids exiting permeable ocean crust at mid-ocean ridge crests and unsedimented/thinly sedimented ridge flanks have DOC concentrations that are lower by 20-25 μM than deep seawater (36-39 μM; typical vent fluid DOC concentrations are 11-19 μM; Lang et al, 2006;Lin et al, 2012). Global DOC losses in hydrothermal systems are low, <0.0002 PgC year −1 , but measurements are few and this may be an underestimate.…”

Section: Composition and The Cycling Of Refractory Dommentioning

confidence: 99%

Chemical Characterization and Cycling of Dissolved Organic Matter

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2015

Biogeochemistry of Marine Dissolved Organic Matter

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“…Thus, the circulation of deep ocean water through submarine hydrothermal systems plays an important role in global biogeochemical cycles, including the global carbon cycle. This is due to the fact that there is nearly as much fixed carbon as dissolved organic carbon (DOC) in the deep ocean (>1000 m; 662 Pg C; Hansell et al, 2009) as there is CO 2 in the atmosphere (750 Pg C; Siegenthaler and Sarmiento, 1993), and that seawater DOC is removed during its flow path in the basement (Lang et al, 2006;Lin et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Dissolved amino acids in oceanic basaltic basement fluids

Lin

Amend

LaRowe

et al. 2015

Geochimica et Cosmochimica Acta

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The oceanic basaltic basement contains the largest aquifer on Earth and potentially plays an important role in the global carbon cycle as a net sink for dissolved organic carbon (DOC). However, few details of the organic matter cycling in the subsurface are known because great water depths and thick sediments typically hinder direct access to this environment. In an effort to examine the role of water-rock-microorganism interaction on organic matter cycling in the oceanic basaltic crust, basement fluid samples collected from three borehole observatories installed on the eastern flank of the Juan de Fuca Ridge were analyzed for dissolved amino acids. Our data show that dissolved free amino acids (1-13 nM) and dissolved hydrolyzable amino acids (43-89 nM) are present in the basement. The amino acid concentrations in the ridge-flank basement fluids are at the low end of all submarine hydrothermal fluids reported in the literature and are similar to those in deep seawater. Amino acids in recharging deep seawater, in situ amino acid production, and diffusional input from overlying sediments are potential sources of amino acids in the basement fluids. Thermodynamic modeling shows that amino acid synthesis in the basement can be sustained by energy supplied from inorganic substrates via chemolithotrophic metabolisms. Furthermore, an analysis of amino acid concentrations and compositions in basement fluids support the notion that heterotrophic activity is ongoing. Similarly, the enrichment of acidic amino acids and depletion of hydrophobic ones relative to sedimentary particulate organic matter suggests that surface sorption and desorption also alters amino acids in the basaltic basement. In summary, although the oceanic basement aquifer is a net sink for deep seawater DOC, similar amino acid concentrations in basement aquifer and deep seawater suggest that DOC is preferentially removed in the basement over dissolved amino acids. Our data also suggest that organic carbon cycling occurs in the oceanic basaltic basement, where an active subsurface biosphere is likely responsible for amino acid synthesis and degradation.

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Inorganic chemistry, gas compositions and dissolved organic carbon in fluids from sedimented young basaltic crust on the Juan de Fuca Ridge flanks

Cited by 57 publications

References 68 publications

Microbial diversity within basement fluids of the sediment-buried Juan de Fuca Ridge flank

Microbial diversity within basement fluids of the sediment-buried Juan de Fuca Ridge flank

Chemical Characterization and Cycling of Dissolved Organic Matter

Dissolved amino acids in oceanic basaltic basement fluids

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