Electrochemical ocean iron fertilization and alkalinity enhancement approach toward CO sequestration.

Achieving net-zero emissions by 2050 requires the development of effective negative emission techniques, including ocean-based approaches for CO sequestration. However, the implementation and testing of marine CO removal (mCDR) techniques such as ocean iron fertilization (OIF) or ocean alkalinity enhancement (OAE) face significant challenges. Herein, a novel self-operating electrochemical technology is presented that not only combines OIF and OAE, but also recovers hydrogen gas (H) from seawater, hence offering a promising solution for achieving quantifiable and transparent large-scale mCDR.

RotoBOD─Quantifying Oxygen Consumption by Suspended Particles and Organisms.

Sinking or floating is the natural state of planktonic organisms and particles in the ocean. Simulating these conditions is critical when making measurements, such as respirometry, because they allow the natural exchange of substrates and products between sinking particles and water flowing around them and prevent organisms that are accustomed to motion from changing their metabolism. We developed a rotating incubator, the RotoBOD (named after its capability to rotate and determine biological oxygen demand, BOD), that uniquely enables automated oxygen measurements in small volumes while keeping the samples in their natural state of suspension.

The future of ocean health.

Human and environmental health are inextricably linked. Yet ocean ecosystem health is declining because of anthropogenic pollution, overexploitation, and the effects of global climate change. These problems affect billions of people dependent on oceans for their lives, livelihoods, and cultural practices.

Spreading pathways of Pilgrim Nuclear Power Station wastewater in and around Cape Cod Bay: Estimates from ocean drifter observations.

Near-surface drifter observations were used to study the spreading pathways in and around the Cape Cod Bay from a source region located just offshore of the Pilgrim Nuclear Power Station. The study was motivated by the recent closing of the power plant and a possible release of accumulated wastewater. The investigation applies several different techniques to the drifter data set to estimate and quantify various aspects of the circulation and spreading.

A Visual Tour of Carbon Export by Sinking Particles.

To better quantify the ocean's biological carbon pump, we resolved the diversity of sinking particles that transport carbon into the ocean's interior, their contribution to carbon export, and their attenuation with depth. Sinking particles collected in sediment trap gel layers from four distinct ocean ecosystems were imaged, measured, and classified. The size and identity of particles was used to model their contribution to particulate organic carbon (POC) flux.

Review of the analysis of Th in small volume (2-4 L) seawater samples: improvements and recommendations.

The short-lived radionuclide Th is widely used to study particle scavenging and transport from the upper ocean to deeper waters. This manuscript optimizes, reviews and validates the collection, processing and analyses of total Th in seawater and suggests areas of further improvements. The standard Th protocol method consists of scavenging Th from seawater via a MnO precipitate, beta counting, and using chemical recoveries determined by adding Th.

Distribution and Evolution of Fukushima Dai-ichi derived Cs, Sr, and I in Surface Seawater off the Coast of Japan.

The Fukushima Dai-ichi Nuclear Power Plants (FDNPPs) accident in 2011 led to an unprecedented release of radionuclides into the environment. Particularly important are Sr and Cs due to their known health detriments and long half-lives ( ≈ 30 y) relative to ecological systems. These radionuclides can be combined with the longer-lived I ( = 15.

The value of scientific research on the ocean's biological carbon pump.

The ocean's biological carbon pump (BCP) sequesters carbon from the surface to the deep ocean and seabed, constituting one of Earth's most valuable ecosystem services. Significant uncertainty exists surrounding the amounts and rates of organic carbon sequestered in the oceans, however. With improved understanding of BCP sequestration, especially its scale, world policymakers would be positioned to make more informed decisions regarding the mitigation of carbon emissions.

Desorption Behavior of Fukushima-derived Radiocesium in Sand Collected from Yotsukura Beach in Fukushima Prefecture.

Beach sand samples were collected along a coastal area 32 km south of the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Fukushima Prefecture, Japan, 5 years after the FDNPP accident. Desorption experiments were performed on the sand samples using seawater in a batch experimental system to understand the forms of existence of radiocesium in sand and their desorption behavior in a coastal environment. The percentage of radiocesium desorption decreased exponentially with an increase in the number of desorption experiments for the four sand samples, with Cs radioactivity from 16 to 1077 Bq kg at surface and deeper layers from three sites.

Metrics that matter for assessing the ocean biological carbon pump.

The biological carbon pump (BCP) comprises wide-ranging processes that set carbon supply, consumption, and storage in the oceans' interior. It is becoming increasingly evident that small changes in the efficiency of the BCP can significantly alter ocean carbon sequestration and, thus, atmospheric CO and climate, as well as the functioning of midwater ecosystems. Earth system models, including those used by the United Nation's Intergovernmental Panel on Climate Change, most often assess POC (particulate organic carbon) flux into the ocean interior at a fixed reference depth.

Results of an Ocean Trial of the Symbiotic Machine for Ocean uRanium Extraction.

Amidoxime-based adsorbents have become highly promising for seawater uranium extraction. However, current deployment schemes are stand-alone, intermittent operation systems that have significant practical and economic challenges. This paper presents two 1:10 scale prototypes of a Symbiotic Machine for Ocean uRanium Extraction (SMORE) which pairs with an existing offshore structure.

Lingering radioactivity at the Bikini and Enewetak Atolls.

We made an assessment of the levels of radionuclides in the ocean waters, seafloor and groundwater at Bikini and Enewetak Atolls where the US conducted nuclear weapons tests in the 1940's and 50's. This included the first estimates of submarine groundwater discharge (SGD) derived from radium isotopes that can be used here to calculate radionuclide fluxes in to the lagoon waters. While there is significant variability between sites and sample types, levels of plutonium (Pu) remain several orders of magnitude higher in lagoon seawater and sediments than what is found in rest of the world's oceans.

Unexpected source of Fukushima-derived radiocesium to the coastal ocean of Japan.

There are 440 operational nuclear reactors in the world, with approximately one-half situated along the coastline. This includes the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), which experienced multiple reactor meltdowns in March 2011 followed by the release of radioactivity to the marine environment. While surface inputs to the ocean via atmospheric deposition and rivers are usually well monitored after a nuclear accident, no study has focused on subterranean pathways.

Recent Transport History of Fukushima Radioactivity in the Northeast Pacific Ocean.

The large inventory of radioactivity released during the March, 2011 Fukushima Dai-ichi nuclear reactor accident in Japan spread rapidly across the North Pacific Ocean and was first observed at the westernmost station on Line P, an oceanographic sampling line extending 1500 km westward of British Columbia (BC), Canada in June 2012. Here, time series measurements of Cs and Cs in seawater on Line P and on the CLIVAR-P16N 152°W line reveal the recent transport history of the Fukushima radioactivity tracer plume through the northeast Pacific Ocean. During 2013 and 2014 the Fukushima plume spread onto the Canadian continental shelf and by 2015 and early 2016 it reached Cs values of 6-8 Bq/m in surface water along Line P.

Potential Releases of I, U, and Pu Isotopes from the Fukushima Dai-ichi Nuclear Power Plants to the Ocean from 2013 to 2015.

After the Fukushima Dai-ichi nuclear accident, many efforts were put into the determination of the presence of Cs, Cs, I, and other gamma-emitting radionuclides in the ocean, but minor work was done regarding the monitoring of less volatile radionuclides, pure beta-ray emitters or simply radionuclides with very long half-lives. In this study we document the temporal evolution of I, U, and Pu isotopes (Pu and Pu) in seawater sampled during four different cruises performed 2, 3, and 4 years after the accident, and we compare the results to Cs collected at the same stations and depths. Our results show that concentrations of I are systematically above the nuclear weapon test levels at stations located close to the FDNPP, with a maximum value of 790 × 10 at·kg, that exceeds all previously reported I concentrations in the Pacific Ocean.

Fukushima Daiichi-Derived Radionuclides in the Ocean: Transport, Fate, and Impacts.

The events that followed the Tohoku earthquake and tsunami on March 11, 2011, included the loss of power and overheating at the Fukushima Daiichi nuclear power plants, which led to extensive releases of radioactive gases, volatiles, and liquids, particularly to the coastal ocean. The fate of these radionuclides depends in large part on their oceanic geochemistry, physical processes, and biological uptake. Whereas radioactivity on land can be resampled and its distribution mapped, releases to the marine environment are harder to characterize owing to variability in ocean currents and the general challenges of sampling at sea.

Reassessment of (90)Sr, (137)Cs, and (134)Cs in the Coast off Japan Derived from the Fukushima Dai-ichi Nuclear Accident.

The years following the Fukushima Dai-ichi nuclear power plant (FDNPP) accident, the distribution of (90)Sr in seawater in the coast off Japan has received limited attention. However, (90)Sr is a major contaminant in waters accumulated within the nuclear facility and in the storage tanks. Seawater samples collected off the FDNPP in September 2013 showed radioactive levels significantly higher than pre-Fukushima levels within 6 km off the FDNPP.

Tracking the Fate of Particle Associated Fukushima Daiichi Cesium in the Ocean off Japan.

A three year time-series of particle fluxes is presented from sediment traps deployed at 500 and 1000 m at a site 115 km southeast of Fukushima Daiichi Nuclear Power Plant (FDNPP). Results show a high fraction of lithogenic material and mass flux peaks that do not align between the trap depths, suggesting a lateral source of sediments. Fukushima cesium-137 and cesium-134 were enhanced in flux peaks that, given variations in trap (137)Cs/(210)Pbex ratios, are characteristic of material derived from shelf and slope sediments found from <120 to >500 m.

Fukushima-derived radionuclides in the ocean and biota off Japan.

The Tōhoku earthquake and tsunami of March 11, 2011, resulted in unprecedented radioactivity releases from the Fukushima Dai-ichi nuclear power plants to the Northwest Pacific Ocean. Results are presented here from an international study of radionuclide contaminants in surface and subsurface waters, as well as in zooplankton and fish, off Japan in June 2011. A major finding is detection of Fukushima-derived (134)Cs and (137)Cs throughout waters 30-600 km offshore, with the highest activities associated with near-shore eddies and the Kuroshio Current acting as a southern boundary for transport.

Impacts of the Fukushima nuclear power plants on marine radioactivity.

The impacts on the ocean of releases of radionuclides from the Fukushima Dai-ichi nuclear power plants remain unclear. However, information has been made public regarding the concentrations of radioactive isotopes of iodine and cesium in ocean water near the discharge point. These data allow us to draw some basic conclusions about the relative levels of radionuclides released which can be compared to prior ocean studies and be used to address dose consequences as discussed by Garnier-Laplace et al.