Depth perception: the need to report ocean biogeochemical rates as functions of temperature, not depth.

For over 50 years, ocean scientists have oddly represented ocean oxygen consumption rates as a function of depth but not temperature in most biogeochemical models. This unique tradition or tactic inhibits useful discussion of climate change impacts, where specific and fundamental temperature-dependent terms are required. Tracer-based determinations of oxygen consumption rates in the deep sea are nearly universally reported as a function of depth in spite of their well-known microbial basis.

Ocean ventilation and deoxygenation in a warming world: introduction and overview.

Changes of ocean ventilation rates and deoxygenation are two of the less obvious but important indirect impacts expected as a result of climate change on the oceans. They are expected to occur because of (i) the effects of increased stratification on ocean circulation and hence its ventilation, due to reduced upwelling, deep-water formation and turbulent mixing, (ii) reduced oxygenation through decreased oxygen solubility at higher surface temperature, and (iii) the effects of warming on biological production, respiration and remineralization. The potential socio-economic consequences of reduced oxygen levels on fisheries and ecosystems may be far-reaching and significant.

Use of a free ocean CO₂ enrichment (FOCE) system to evaluate the effects of ocean acidification on the foraging behavior of a deep-sea urchin.

The influence of ocean acidification in deep-sea ecosystems is poorly understood but is expected to be large because of the presumed low tolerance of deep-sea taxa to environmental change. We used a newly developed deep-sea free ocean CO2 enrichment (dp-FOCE) system to evaluate the potential consequences of future ocean acidification on the feeding behavior of a deep-sea echinoid, the sea urchin, Strongylocentrotus fragilis. The dp-FOCE system simulated future ocean acidification inside an experimental enclosure where observations of feeding behavior were performed.

A review of advances in deep-ocean Raman spectroscopy.

We review the rapid progress made in the applications of Raman spectroscopy to deep-ocean science. This is made possible by deployment of instrumentation on remotely operated vehicles used for providing power and data flow and for precise positioning on targets of interest. Early prototype systems have now been replaced by compact and robust units that have been deployed well over 100 times on an expeditionary basis over a very wide range of ocean depths without failure.

Geochemistry of chemical weapon breakdown products on the seafloor: 1,4-thioxane in seawater.

The long-term fate of chemical weapon debris disposed of in the ocean some 50 years ago, now sinking into marine sediments and leaking into the ocean environment, is poorly known. Direct evidence exists showing chemical weapon agents actively being released on the sea floor with detrimental effects including harm to marine life. Thus there is strong interest in determining the fate and lifetime of these materials, their decomposition products, and the affected zones around these sites.

Clathrate hydrates in nature.

Scientific knowledge of natural clathrate hydrates has grown enormously over the past decade, with spectacular new findings of large exposures of complex hydrates on the sea floor, the development of new tools for examining the solid phase in situ, significant progress in modeling natural hydrate systems, and the discovery of exotic hydrates associated with sea floor venting of liquid CO2. Major unresolved questions remain about the role of hydrates in response to climate change today, and correlations between the hydrate reservoir of Earth and the stable isotopic evidence of massive hydrate dissociation in the geologic past. The examination of hydrates as a possible energy resource is proceeding apace for the subpermafrost accumulations in the Arctic, but serious questions remain about the viability of marine hydrates as an economic resource.

Seeing a deep ocean CO2 enrichment experiment in a new light: laser raman detection of dissolved CO2 in seawater.

We used a newly developed in situ laser Raman spectrometer (LRS) for detection of elevated levels of dissolved CO2 in seawater. The experiment was carried out at 500 m depth, 6 degrees C, to examine new protocols for detection of CO2-enriched seawater emanating from a liquid CO2 source in the ocean, and to determine current detection limits under field conditions. A system of two interconnected 5 L chambers was built, with flow between them controlled by a valve and pump system, and this unit was mounted on an ROV.

Field studies on the formation of sinking CO2 particles for ocean carbon sequestration: effects of injector geometry on particle density and dissolution rate and model simulation of plume behavior.

We have carried out the second phase of field studies to determine the effectiveness of a coflow injector which mixes liquid CO2 and ambient seawater to produce a hydrate slurry as a possible CO2 delivery method for ocean carbon sequestration. The experiments were carried out at ocean depths of 1000-1300 m in Monterey Bay, CA, using a larger injector than that initially employed under remotely operated vehicle control and imaging of the product. Solidlike composite particles comprised of water, solid CO2 hydrate, and liquid CO2 were produced in both studies.

Experimental determination of the fate of rising CO2 droplets in seawater.

Direct oceanic disposal of fossil fuel CO2 is being considered as a possible means to moderate the growth rate of CO2 in the atmosphere. We have measured the rise rate and dissolution rate of freely released CO2 droplets in the open ocean to provide fundamental data for carbon sequestration options. A small amount of liquid CO2 was released at 800 m, at 4.