ALBERT

Description: Dataset: underway Cesium Isotopes

Description: This underway Cesium Isotopes dataset includes the following data: Cs137 and Cs134 concentrations collected for the project called "Establishing Radionuclide Levels in the Atlantic and Pacific Oceans Originating from the Fukushima Daiichi Nuclear Power Facility" (Fukushima Radionuclide Levels). For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description' is included in the supplemental file 'Dataset_description.pdf'.

Description: Gordon and Betty Moore Foundation (Moore) 3007, NSF Division of Ocean Sciences (NSF OCE) OCE-1136693

Description: Dataset: hydrocast Cesium isotopes

Description: This hydrocast Cesium isotopes dataset includes cesium-134 and cesium-137 concentrations determined from samples taken for the Fukushima Radionuclide Project. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description' is included in the supplemental file 'Dataset_description.pdf'.

Description: Gordon and Betty Moore Foundation (Moore) 3007, NSF Division of Ocean Sciences (NSF OCE) OCE-1136693

Description: Dataset: Niskin bottle samples

Description: This Establishing Radionuclide Levels in the Atlantic and Pacific Oceans Originating from the Fukushima Daiichi Nuclear Power Facility (Fukushima Radionuclide Levels) Niskin bottle samples dataset includes the following data: calibrated CTD measurements of salinity and oxygen and Niskin bottle water samples. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf'. A full dataset description is included in the supplemental file 'Dataset_description.pdf'.

Description: Gordon and Betty Moore Foundation Marine Microbiology Initiative (MooreMarMicro), NSF Division of Ocean Sciences (NSF OCE) OCE-1136693

Description: VERTIGO project sediment trap flux data including mass, elements and phytoplankton pigment data from KM0414 and RR_K2 cruises. See Sampling and Analytical Protocols document for further information.

Description: The main goal of VERTIGO is the investigation of the mechanisms that control the efficiency of particle transport through the mesopelagic portion of the water column. Question: What controls the efficiency of particle transport between the surface and deep ocean? More specifically, what is the fate of sinking particles leaving the upper ocean and what factors influence remineralization length scales for different sinking particle classes? VERTIGO researchers have set out to test two basic hypotheses regarding remineralization control, namely: 1. particle source characteristics are the dominant control on the efficiency of particle transport; and/or that 2. mid-water processing, either by zooplankton or bacteria, controls transport efficiency. To test their hypotheses, they will conduct process studies in the field focused on particle flux and composition changes in the upper 500-1000m of the ocean. The basic approach is to examine changes in particle composition and flux with depth within a given source region using a combination of approaches, many of which are new to the field. These include neutrally buoyant sediment traps, particle pumps, settling columns and respiration chambers, along with the development of new biological and geochemical tools for an integrated biogeochemical assessment of the biological pump. Three week process study cruises have been planned at two sites - the Hawaii Ocean Time-series site (HOT) and a new moored time-series site in the subarctic NW Pacific (Japanese site K2; 47°N 160°E) - where there are strong contrasts in rates of production, export, particle composition and expected remineralization length scales. Evidence for variability in the flux vs. depth relationship of sinking particles is not in dispute but the controls on particle transport efficiency through the twilight zone remain poorly understood. A lack of reliable flux and particle characterization data within the twilight zone has hampered our ability to make progress in this area, and no single approach is likely to resolve these issues. The proposed study will apply quantitative modeling to determine the net effects of the individual particle processes on the effective transport of carbon and other elements, and to place the shipboard observations in the context of spatial and temporal variations in these processes. For rapid progress in this area, we have organized this effort as a group proposal taking advantage of expertise in the US and international community. The efficiency of particle transport is important for an accurate assessment of the ocean C sink. Globally, the magnitude and efficiency of the biological pump will in part modulate levels of atmospheric CO2. We maintain that to understand present day ocean C sequestration and to evaluate potential strategies for enhancing sequestration, we need to assess possible changes in the efficiency of particle transport due to climate variability or via purposeful manipulations of C uptake, such as via iron fertilization.

Description: NSF Division of Ocean Sciences (NSF-OCE) OCE-0301139

Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Estapa, M., Valdes, J., Tradd, K., Sugar, J., Omand, M., & Buesseler, K. The neutrally buoyant sediment trap: two decades of progress. Journal of Atmospheric and Oceanic Technology, 37(6), (2020): 957-973, https://doi.org/10.1175/JTECH-D-19-0118.1.

Description: The biological carbon flux from the ocean’s surface into its interior has traditionally been sampled by sediment traps, which physically intercept sinking particulate matter. However, the manner in which a sediment trap interacts with the flow field around it can introduce hydrodynamic biases, motivating the development of neutral, self-ballasting trap designs. Here, the performance of one of these designs, the neutrally buoyant sediment trap (NBST), is described and evaluated. The NBST has been successfully used in a number of scientific studies since a prototype was last described in the literature two decades ago, with extensive modifications in subsequent years. Originated at Woods Hole Oceanographic Institution, the NBST is built around a profiling float and carries cylindrical collection tubes, a feature that distinguishes it from other neutral traps described in the literature. This paper documents changes to the device that have been implemented over the last two decades, including wider trap tubes; Iridium Communications, Inc., satellite communications; and the addition of polyacrylamide gel collectors and optical sedimentation sensors. Information is also provided with the intent of aiding the development of similar devices by other researchers, including the present adaptation of the concept to utilize commercially available profiling float hardware. The performance of NBSTs built around commercial profiling floats is comparable to NBSTs built around customized floats, albeit with some additional operational considerations. Data from recent field studies comparing NBSTs and traditional, surface-tethered sediment traps are used to illustrate the performance of the instrument design. Potential improvements to the design that remain to be incorporated through future work are also outlined.

Description: Funding supporting this work has come from multiple sources over the years: the NSF Chemical Oceanography and Carbon and Water programs (most recently OCE-1660012 and OCE-1659995), the NASA Ocean Biology and Biogeochemistry and New Investigator programs (80NSSC17K0662 and NNX14AM01G), and the Woods Hole Oceanographic Institution Technology Award.