Valentine David L.

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Valentine

First Name

David L.

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0000-0001-5914-9107

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Dissolved methane distributions and air-sea flux in the plume of a massive seep field, Coal Oil Point, California

(American Geophysical Union, 2007-11-24) Mau, Susan ; Valentine, David L. ; Clark, Jordan F. ; Reed, Justin ; Camilli, Richard ; Washburn, Libe

Large quantities of natural gas are emitted from the seafloor into the stratified coastal ocean near Coal Oil Point, Santa Barbara Channel, California. Methane was quantified in the down current surface water at 79 stations in a 280 km2 study area. The methane plume spread over an area of ~70 km2 and emitted on the order of 5 × 104 mol d−1 to the atmosphere. A monthly time series at 14 stations showed variable methane concentrations which were correlated with changing sub-mesoscale surface currents. Air-sea fluxes estimated from the time series indicate that the air-sea flux derived for the 280 km2 area is representative of the daily mean flux from this area. Only 1% of the dissolved methane originating from Coal Oil Point enters the atmosphere within the study area. Most of it appears to be transported below the surface and oxidized by microbial activity.
Fate of dispersants associated with the Deepwater Horizon oil spill

( 2011-01-05) Kujawinski, Elizabeth B. ; Kido Soule, Melissa C. ; Valentine, David L. ; Boysen, Angela K. ; Longnecker, Krista ; Redmond, Molly C.

Response actions to the Deepwater Horizon oil spill included the injection of ~771,000 gallons (2,900,000 L) of chemical dispersant into the flow of oil near the seafloor. Prior to this incident, no deepwater applications of dispersant had been conducted and thus no data exists on the environmental fate of dispersants in deepwater. We used ultrahigh resolution mass spectrometry and liquid chromatography with tandem mass spectrometry (LC/MS/MS) to identify and quantify one key ingredient of the dispersant, the anionic surfactant DOSS (dioctyl sodium sulfosuccinate), in the Gulf of Mexico deepwater during active flow and again after flow had ceased. Here we show that DOSS was sequestered in deepwater hydrocarbon plumes at 1000-1200m water depth and did not intermingle with surface dispersant applications. Further, its concentration distribution was consistent with conservative transport and dilution at depth and it persisted up to 300 km from the well, 64 days after deepwater dispersant applications ceased. We conclude that DOSS was selectively associated with the oil and gas phases in the deepwater plume, yet underwent negligible, or slow, rates of biodegradation in the affected waters. These results provide important constraints on accurate modeling of the deepwater plume and critical geochemical contexts for future toxicological studies.
Ideas and perspectives: a strategic assessment of methane and nitrous oxide measurements in the marine environment

(European Geosciences Union, 2020-11-26) Wilson, Samuel T. ; Al-Haj, Alia N. ; Bourbonnais, Annie ; Frey, Claudia ; Fulweiler, Robinson W. ; Kessler, John D. ; Marchant, Hannah K. ; Milucka, Jana ; Ray, Nicholas E. ; Suntharalingam, Parvadha ; Thornton, Brett F. ; Upstill-Goddard, Robert C. ; Weber, Thomas S. ; Arévalo-Martínez, Damian L. ; Bange, Hermann W. ; Benway, Heather M. ; Bianchi, Daniele ; Borges, Alberto V. ; Chang, Bonnie X. ; Crill, Patrick M. ; del Valle, Daniela A. ; Farías, Laura ; Joye, Samantha B. ; Kock, Annette ; Labidi, Jabrane ; Manning, Cara C. ; Pohlman, John W. ; Rehder, Gregor ; Sparrow, Katy J. ; Tortell, Philippe D. ; Treude, Tina ; Valentine, David L. ; Ward, Bess B. ; Yang, Simon ; Yurganov, Leonid N.

In the current era of rapid climate change, accurate characterization of climate-relevant gas dynamics – namely production, consumption, and net emissions – is required for all biomes, especially those ecosystems most susceptible to the impact of change. Marine environments include regions that act as net sources or sinks for numerous climate-active trace gases including methane (CH4) and nitrous oxide (N2O). The temporal and spatial distributions of CH4 and N2O are controlled by the interaction of complex biogeochemical and physical processes. To evaluate and quantify how these mechanisms affect marine CH4 and N2O cycling requires a combination of traditional scientific disciplines including oceanography, microbiology, and numerical modeling. Fundamental to these efforts is ensuring that the datasets produced by independent scientists are comparable and interoperable. Equally critical is transparent communication within the research community about the technical improvements required to increase our collective understanding of marine CH4 and N2O. A workshop sponsored by Ocean Carbon and Biogeochemistry (OCB) was organized to enhance dialogue and collaborations pertaining to marine CH4 and N2O. Here, we summarize the outcomes from the workshop to describe the challenges and opportunities for near-future CH4 and N2O research in the marine environment.
Porosity and density of sediments collected Fall 2019 in the Santa Barbara Basin using ROV Jason during R/V Atlantis cruise AT42-19

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-02-08) Treude, Tina ; Valentine, David L.

Sediments were collected in Fall 2019 across three transects in the Santa Barbara Basin using the ROV Jason during R/V Atlantis cruise AT42-19. This dataset consists of the sediment parameters porosity and density. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/867113
Hydrocarbon concentrations, DIC isotopes, nutrients, and cyanobacteria counts from samples collected on R/V Neil Armstrong cruise AR16 in the western north Atlantic during May 2017

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2020-12-03) Valentine, David L. ; Reddy, Christopher M. ; Swarthout, Robert

Hydrocarbon concentrations, DIC isotopes, nutrients, and cyanobacteria counts from samples collected on R/V Neil Armstrong cruise AR16 in the western north Atlantic during May 2017. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/826878
Microbial activity from sediments collected Fall 2019 in the Santa Barbara Basin using ROV Jason during R/V Atlantis cruise AT42-19

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-02-08) Treude, Tina ; Valentine, David L.

Sediments were collected in Fall 2019 across three transects in the Santa Barbara Basin using the ROV Jason during R/V Atlantis cruise AT42-19. Microbial activity in the sediments was determined by measuring sulfate reduction rates. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/867221
Nutrients and pigments from HPLC analysis for fire ash deposition to coastal ocean study, southern California, December 2017

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-09-25) Valentine, David L.

Nutrients and pigments from HPLC analysis for fire ash deposition to coastal ocean study, southern California, December 2017. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/765868
Porewater geochemistry of sediments collected Fall 2019 in the Santa Barbara Basin using ROV Jason during R/V Atlantis cruise AT42-19

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-02-08) Treude, Tina ; Valentine, David L.

Sediments were collected in Fall 2019 across three transects in the Santa Barbara Basin using the ROV Jason during R/V Atlantis cruise AT42-19. Porewater was separated from the sediments and geochemical properties measured. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/867007
Production of two highly abundant 2-methyl-branched fatty acids by blooms of the globally significant marine cyanobacteria Trichodesmium erythraeum

(American Chemical Society, 2021-08-26) Gosselin, Kelsey M. ; Nelson, Robert K. ; Spivak, Amanda C. ; Sylva, Sean P. ; Van Mooy, Benjamin A. S. ; Aeppli, Christoph ; Sharpless, Charles M. ; O’Neil, Gregory W. ; Arrington, Eleanor C. ; Reddy, Christopher M. ; Valentine, David L.

The bloom-forming cyanobacteria Trichodesmium contribute up to 30% to the total fixed nitrogen in the global oceans and thereby drive substantial productivity. On an expedition in the Gulf of Mexico, we observed and sampled surface slicks, some of which included dense blooms of Trichodesmium erythraeum. These bloom samples contained abundant and atypical free fatty acids, identified here as 2-methyldecanoic acid and 2-methyldodecanoic acid. The high abundance and unusual branching pattern of these compounds suggest that they may play a specific role in this globally important organism.
Time course experiment related data to validate incubation duration for methane oxidation rate measurement of the deep Santa Barbara Basin water column from September 2019 (BASIN project)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-04-20) Qin, Qianhui ; Valentine, David L. ; Treude, Tina ; Kinnaman, Franklin S ; Gosselin, Kelsey M ; Liu, Na

This time course experiment was performed to test if the uptake rate of 3H-CH4 is linear over the chosen incubation time (3 days) for the seawater samples. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/872687
Initial Oxygen Concentration Alteration Experiment Data of the Deep Santa Barbara Basin Water Column from October 2019 (BASIN project)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-04-20) Qin, Qianhui ; Valentine, David L. ; Treude, Tina ; Kinnaman, Franklin S ; Gosselin, Kelsey M ; Liu, Na

An oxygen concentration alteration experiment was performed to test the influence of oxygen concentration on methane oxidation rate. Together with the methane concentration alteration experiment, the purpose of this experiment was to test the assumption that methane oxidation in the Santa Barbara Basin deep water column follows first order kinetics. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/872665
Determining the flux of methane into Hudson Canyon at the edge of methane clathrate hydrate stability

(John Wiley & Sons, 2016-10-13) Weinstein, Alexander ; Navarrete, Luis ; Ruppel, Carolyn D. ; Weber, Thomas C. ; Leonte, Mihai ; Kellermann, Matthias Y. ; Arrington, Eleanor C. ; Valentine, David L. ; Scranton, Mary I. ; Kessler, John D.

Methane seeps were investigated in Hudson Canyon, the largest shelf-break canyon on the northern U.S. Atlantic Margin. The seeps investigated are located at or updip of the nominal limit of methane clathrate hydrate stability. The acoustic identification of bubble streams was used to guide water column sampling in a 32 km2 region within the canyon's thalweg. By incorporating measurements of dissolved methane concentration with methane oxidation rates and current velocity into a steady state box model, the total emission of methane to the water column in this region was estimated to be 12 kmol methane per day (range: 6–24 kmol methane per day). These analyses suggest that the emitted methane is largely retained inside the canyon walls below 300 m water depth, and that it is aerobically oxidized to near completion within the larger extent of Hudson Canyon. Based on estimated methane emissions and measured oxidation rates, the oxidation of this methane to dissolved CO2 is expected to have minimal influences on seawater pH.
Ocean Dumping of Containerized DDT Waste Was a Sloppy Process

(American Chemical Society, 2019-03-04) Kivenson, Veronika ; Lemkau, Karin L. ; Pizarro, Oscar ; Yoerger, Dana R. ; Kaiser, Carl ; Nelson, Robert K. ; Carmichael, Catherine A. ; Paul, Blair G. ; Reddy, Christopher M. ; Valentine, David L.

Industrial-scale dumping of organic waste to the deep ocean was once common practice, leaving a legacy of chemical pollution for which a paucity of information exists. Using a nested approach with autonomous and remotely operated underwater vehicles, a dumpsite offshore California was surveyed and sampled. Discarded waste containers littered the site and structured the suboxic benthic environment. Dichlorodiphenyltrichloroethane (DDT) was reportedly dumped in the area, and sediment analysis revealed substantial variability in concentrations of p,p-DDT and its analogs, with a peak concentration of 257 μg g–1, ∼40 times greater than the highest level of surface sediment contamination at the nearby DDT Superfund site. The occurrence of a conspicuous hydrocarbon mixture suggests that multiple petroleum distillates, potentially used in DDT manufacture, contributed to the waste stream. Application of a two end-member mixing model with DDTs and polychlorinated biphenyls enabled source differentiation between shelf discharge versus containerized waste. Ocean dumping was found to be the major source of DDT to more than 3000 km2 of the region’s deep seafloor. These results reveal that ocean dumping of containerized DDT waste was inherently sloppy, with the contents readily breaching containment and leading to regional scale contamination of the deep benthos.
Chemical data quantify Deepwater Horizon hydrocarbon flow rate and environmental distribution

( 2011-11-11) Ryerson, Thomas B. ; Camilli, Richard ; Kessler, John D. ; Kujawinski, Elizabeth B. ; Reddy, Christopher M. ; Valentine, David L. ; Atlas, Elliot ; Blake, Donald R. ; de Gouw, Joost ; Meinardi, Simone ; Parrish, David D. ; Peischl, Jeff ; Seewald, Jeffrey S. ; Warneke, Carsten

Detailed airborne, surface, and subsurface chemical measurements, primarily obtained in May and June 2010, are used to quantify initial hydrocarbon compositions along different transport pathways – in deep subsurface plumes, in the initial surface slick, and in the atmosphere – during the Deepwater Horizon (DWH) oil spill. Atmospheric measurements are consistent with a limited area of surfacing oil, with implications for leaked hydrocarbon mass transport and oil drop size distributions. The chemical data further suggest relatively little variation in leaking hydrocarbon composition over time. While readily soluble hydrocarbons made up ~25% of the leaking mixture by mass, subsurface chemical data show these compounds made up ~69% of the deep plume mass; only ~31% of deep plume mass was initially transported in the form of trapped oil droplets. Mass flows along individual transport pathways are also derived from atmospheric and subsurface chemical data. Subsurface hydrocarbon composition, dissolved oxygen, and dispersant data are used to provide a new assessment of release of hydrocarbons from the leaking well. We use the chemical measurements to estimate that (7.8±1.9) x106 kg of hydrocarbons leaked on June 10, 2010, directly accounting for roughly three-quarters of the total leaked mass on that day. The average environmental release rate of (10.1 ± 2.0) x106 kg/day derived using atmospheric and subsurface chemical data agrees within uncertainties with the official average leak rate of (10.2 ± 1.0) x106 kg/day derived using physical and optical methods.
Climatically driven emissions of hydrocarbons from marine sediments during deglaciation

( 2006-07-31) Hill, T. M. ; Kennett, J. P. ; Valentine, David L. ; Yang, Z. ; Reddy, Christopher M. ; Nelson, Robert K. ; Behl, R. J. ; Robert, C. ; Beaufort, L.

Marine hydrocarbon seepage emits oil and gas, including methane (~30 Tg CH4/year), to the ocean and atmosphere. Sediments from the California margin contain preserved tar, primarily formed via hydrocarbon weathering at the sea surface. We present a record of variation in the abundance of tar in sediments for the past 32ky, providing evidence for increases in hydrocarbon emissions prior to and during Termination IA (16-14 ka) and again over Termination IB (11-10 ka). Our study provides the first direct evidence for increased hydrocarbon seepage associated with deglacial warming via tar abundance in marine sediments, independent of previous geochemical proxies. Climate-sensitive gas hydrates may modulate thermogenic hydrocarbon seepage during deglaciation.
Time series of oxygen, nitrate, methane concentrations and methane oxidation rates of the Santa Barbara Basin deep water column from 2019-2020 (BASIN project)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-04-20) Qin, Qianhui ; Valentine, David L. ; Treude, Tina ; Kinnaman, Franklin S ; Gosselin, Kelsey M ; Liu, Na

Time series of water column parameters (oxygen, nitrate, methane concentrations and methane oxidation rates) are sampled and measured to show the changes related to methane biogeochemistry during a deoxygenation and reoxygenation event in the deep Santa Barbara water column (440-583m). For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/872703
Using a Ladder of Seeps with computer decision processes to explore for and evaluate cold seeps on the Costa Rica active margin

(Frontiers Media, 2021-03-11) Vrolijk, Peter ; Summa, Lori ; Ayton, Benjamin ; Nomikou, Paraskevi ; Hüpers, Andre ; Kinnaman, Frank ; Sylva, Sean ; Valentine, David L. ; Camilli, Richard

Natural seeps occur at the seafloor as loci of fluid flow where the flux of chemical compounds into the ocean supports unique biologic communities and provides access to proxy samples of deep subsurface processes. Cold seeps accomplish this with minimal heat flux. While individual expertize is applied to locate seeps, such knowledge is nowhere consolidated in the literature, nor are there explicit approaches for identifying specific seep types to address discrete scientific questions. Moreover, autonomous exploration for seeps lacks any clear framework for efficient seep identification and classification. To address these shortcomings, we developed a Ladder of Seeps applied within new decision-assistance algorithms (Spock) to assist in seep exploration on the Costa Rica margin during the R/V Falkor 181210 cruise in December, 2018. This Ladder of Seeps [derived from analogous astrobiology criteria proposed by Neveu et al. (2018)] was used to help guide human and computer decision processes for ROV mission planning. The Ladder of Seeps provides a methodical query structure to identify what information is required to confirm a seep either: 1) supports seafloor life under extreme conditions, 2) supports that community with active seepage (possible fluid sample), or 3) taps fluids that reflect deep, subsurface geologic processes, but the top rung may be modified to address other scientific questions. Moreover, this framework allows us to identify higher likelihood seep targets based on existing incomplete or easily acquired data, including MBES (Multi-beam echo sounder) water column data. The Ladder of Seeps framework is based on information about the instruments used to collect seep information (e.g., are seeps detectable by the instrument with little chance of false positives?) and contextual criteria about the environment in which the data are collected (e.g., temporal variability of seep flux). Finally, the assembled data are considered in light of a Last-Resort interpretation, which is only satisfied once all other plausible data interpretations are excluded by observation. When coupled with decision-making algorithms that incorporate expert opinion with data acquired during the Costa Rica experiment, the Ladder of Seeps proved useful for identifying seeps with deep-sourced fluids, as evidenced by results of geochemistry analyses performed following the expedition.
Initial Methane Concentration Alteration Experiment Data of the Deep Santa Barbara Basin Water Column from October 2019 (BASIN project)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-04-20) Qin, Qianhui ; Valentine, David L. ; Treude, Tina ; Kinnaman, Franklin S ; Gosselin, Kelsey M ; Liu, Na

A methane concentration alteration experiment was performed to test the influence of methane concentration on methane oxidation rate. Together with the oxygen concentration alteration experiment, the purpose of this experiment was to test the assumption that methane oxidation in the Santa Barbara Basin deep water column follows first order kinetics. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/872652
Oxygen isotopes (delta O-18) trace photochemical hydrocarbon oxidation at the sea surface

(American Geophysical Union, 2019-05-31) Ward, Collin P. ; Sharpless, Charles M. ; Valentine, David L. ; Aeppli, Christoph ; Sutherland, Kevin M. ; Wankel, Scott D. ; Reddy, Christopher M.

Although photochemical oxidation is an environmental process that drives organic carbon (OC) cycling, its quantitative detection remains analytically challenging. Here, we use samples from the Deepwater Horizon oil spill to test the hypothesis that the stable oxygen isotope composition of oil (δ18OOil) is a sensitive marker for photochemical oxidation. In less than one‐week, δ18OOil increased from −0.6 to 7.2‰, a shift representing ~25% of the δ18OOC dynamic range observed in nature. By accounting for different oxygen sources (H2O or O2) and kinetic isotopic fractionation of photochemically incorporated O2, which was −9‰ for a wide range of OC sources, a mass balance was established for the surface oil's elemental oxygen content and δ18O. This δ18O‐based approach provides novel insights into the sources and pathways of hydrocarbon photo‐oxidation, thereby improving our understanding of the fate and transport of petroleum hydrocarbons in sunlit waters, and our capacity to respond effectively to future spills.
Methylphosphonate is utilized by commensal microbiota of macroalgae in the oligotrophic Sargasso Sea

(American Geophysical Union, 2023-12-07) Cox, Danielle D. ; Parsons, Rachel J. ; Van Mooy, Benjamin A. S. ; Valentine, David L.

The essential nutrient phosphorus is biologically scarce in the Sargasso Sea, yet the pelagic macroalgae Sargassum, for which this area of the North Atlantic Ocean is named, thrives. We tested the hypothesis that Sargassum holobionts utilize methylphosphonate (MPn) as an alternative source of phosphorus, finding lysis liberated phosphonate-derived methane. The observed activity occurred at concentrations as low as 35 nM MPn and was inhibited by antibiotics, implicating bacterial epibionts of the holobiont capable of MPn lysis at realistic environmental concentrations. Dark incubations resulted in diminished methane production, consistent with commensalism between microbe and host. A survey of macroalgal species inhabiting the Sargasso Sea found ubiquitous capacity for MPn lysis; such capacity was absent in species inhabiting phosphorus-replete waters of the California Current, pointing to phosphorous limitation as a selective pressure. These results suggest that bacterial epibionts of algal communities acquire phosphorus from phosphonates while simultaneously serving as a source of atmospheric methane.

Valentine David L.

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