Global Scale

Who produces methylmercury in the global ocean?

The UNEP Minamata Convention was ratified in August 2017 and aims to protect human health from mercury exposure by reducing anthropogenic, inorganic, mercury emissions. The most toxic and biomagnifying mercury species, methylmercury, is not emitted from anthropogenic or natural sources, but produced in the ocean from inorganic mercury. Marine mercury methylation has been confirmed for […]

Mar / 18 / 2020

Can phytoplankton help us determine the bioavailability of iron in the world ocean?

Joint Science Highlight with US Ocean Carbon and Biogeochemistry (OCB). Iron (Fe) is a key element to life but in seawater it is present at extremely low concentrations. The scarcity of this important micronutrient limits phytoplankton growth in large swaths of the global ocean with consequences to the marine food-web and carbon cycling. Understanding the […]

Feb / 24 / 2020

Neural network as tools to replace oceanic data deficiencies

The importance of the cycle and speciation of nitrate and its isotopes (δ15N) in the ocean does not have to be demonstrated anymore. In an attempt to overcome the difficulty to compare the results of N/δ15N cycle models to a sparse set of data, Rafter and co-workers propose an original approach, based on artificial intelligence […]

Dec / 16 / 2019

New BioGEOTRACES data sets: Connecting pieces of the microbial biogeochemical puzzle

Microorganisms play a central role in the transfer of matter and energy in the marine food web. Microbes depend on micronutrients (e.g. iron, cobalt, zinc, and a host of other trace metals) to catalyze key biogeochemical reactions, and their metabolisms, in turn, directly affect the cycling, speciation, and bioavailability of these compounds. One might therefore […]

Dec / 20 / 2018

More realistic oceanic particle field improved the thorium-230 and protactinium-231 modeling

Thorium-230 (230Th) and protactinium-231 (231Pa) are two geochemical tracers extensively used for investigating particle transport in the ocean and reconstructing past ocean circulation. A key feature in reproducing their distributions by modelling is to understand and constrain as good as possible the scavenging processes, which means: 1) having the good adsorption-desorption kinetic rates and 2) describing […]

Dec / 10 / 2018

52 years of Benthic Nepheloid Layer data!

A data base of 2412 profiles collected using the Lamont Thorndike nephelometer from 1964 to 1984 is used to globally map turbid nepheloid layers by Gardner and co-workers (2018, see reference below). The authors compare maps from that period with maps based on data from 6392 profiles measured using transmissometers from 1979 to 2016 (see […]

Oct / 04 / 2018

Particle distribution in repeated ocean sections and sediment resuspension

This is the first compilation of an expansive data base of transmissometer data on a decadal period of time. More than 7376 stations have been analyzed for “cp” value, a proxy for particle concentrations, by Gardner and co-workers (2018, see reference below). Full water-column sections confirm that particle concentrations are higher in surface waters, decrease […]

Jan / 25 / 2018

Benthic nepheloid layer global compilation: an invaluable resource for GEOTRACES researchers

Models simulating any oceanic tracer biogeochemistry require a good depiction of the particle distribution, key to incorporating properly scavenging-remineralization processes. However, this kind of description is still rare. Gardner and co-workers (2018, see reference below) are providing an exceptional compilation of the Benthic Nepheloid Layers (BNL) around the world. BNLs have been mapped using 6,392 full-depth […]

Nov / 27 / 2017