Particles

Oceanic Margins as sources of lithogenic particulate and dissolved iron in the North Pacific Ocean

Three GEOTRACES Japanese cruises on board the R/V Hakuho Maru allowed establishing basin-scale and full-depth sectional distributions of total dissolvable iron (tdFe), dissolved iron (dFe), and labile particulate iron (lpFe=tdFe – dFe) in the North Pacific Ocean. Zheng and Sohrin (2019, see reference below) also discuss aluminum (Al) and manganese (Mn) data in this work. […]

Mar / 10 / 2020

Informative zinc isotopic fractionation in the Southern Ocean

Ellwood and co-workers (2020, see reference below) established the distribution of dissolved and particulate zinc (dZn and pZn respectively) and its isotopes in the Subantarctic Zone South of Tasmania. Concentration profiles show that zinc has a longer regeneration length scale than phosphorus and of cadmium, but shorter than copper. Modelling of the particulate profiles produced […]

Mar / 09 / 2020

Glacial erosion processes suspected to enhance the lability of particulate iron, with a strong influence on the biological demand in the subantarctic waters

As part of the GEOTRACES process study HEOBI (GIpr05) van der Merwe and co-workers (2019, see reference below) conducted a thorough characterization of the labile and refractory iron phases of the particles discharged to the local seawater by the glacial erosion and rivers of Heard and Mc Donald islands (Southern Indian Ocean). They demonstrate that, together […]

Dec / 16 / 2019

Glacial erosion processes suspected to enhance the lability of particulate iron, with a strong influence on the biological demand in the subantarctic waters

As part of the GEOTRACES process study HEOBI (GIpr05) van der Merwe and co-workers (2019, see reference below) conducted a thorough characterization of the labile and refractory iron phases of the particles discharged to the local seawater by the glacial erosion and rivers of Heard and Mc Donald islands (Southern Indian Ocean). They demonstrate that, together […]

Oct / 08 / 2019

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

Cadmium to phosphorus ratio in euphotic zone particulates: why does it vary?

Bourne and co-workers examine the particulate cadmium to phosphorus ratio (Cd/P) variations of 3 particle fractions (<1µm, 1-51µm and >51µm) from 50 casts covering spatial and temporal scales never reached so far for these parameters. This impressive data set allows them to study the effects of an El Niño, upwelling, large-scale in situ Fe fertilization, low-oxygen conditions, […]

Nov / 01 / 2018

Influence of particle composition on the rate constants of thorium adsorption

Chemical species are constantly exchanged between seawater (solution, D) and particles (solid material, P). This continuous D-P exchange is a key process determining the chemical composition of the ocean. Particles are heterogeneous materials, made of (i) biological material from the surface ocean, (ii) lithogenic material from external inputs to the ocean, and (iii) authigenic (oxyhydr)oxides […]

Sep / 04 / 2018

Contrasting fates of the cadmium-cadmium isotopes in the Kuroshio and Oyashio environmental systems

Yang et al. (2018, see reference below) studied the relative importance of physical and biogeochemical processes on controlling the isotopic composition of dissolved and particulate cadmium (Cd) in a GP18 transect, crossing over the relatively cold and eutrophic Oyashio Extension region and the relatively warm and oligotrophic Kuroshio Extension region. Particulate samples revealed preferential uptake […]

Jul / 18 / 2018

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