Roshan and collaborators present new observations of dissolved iron and its physical speciation in the South Pacific
Jun / 10 / 2020
Hydrothermal
Loihi Seamount, hydrothermal Helium-3 and dissolved iron sources and their dispersion within the Pacific Ocean
As part of the GEOTRACES cruise GP15, Jenkins and co-workers (2020, see reference below) observed large water column anomalies in helium isotopes and trace metal concentrations above the Loihi Seamount (~19°N, 154°W) that extends along the GP15 track for hundreds of kilometers. Expanding their data with historical ones, they observe that the Loihi Helium-3 (3He) […]
May / 04 / 2020
Upwelled hydrothermal iron stimulates massive phytoplankton blooms in the Southern Ocean
Joint Science Highlight with US-Ocean Carbon & Biogeochemistry (US-OCB). In a recent study, Ardyna et al (2019, see reference below) combined observations of profiling floats with historical trace element data and satellite altimetry and ocean color data from the Southern Ocean to reveal that dissolved iron (Fe) of hydrothermal origin can be upwelled to the surface. […]
Oct / 08 / 2019
Using the three thorium isotope toolbox to probe the particle dynamic within an East Pacific Rise hydrothermal plume
The insoluble radiogenic isotopes of thorium (Th) are produced at a known rate in the water column via the decay of soluble uranium (234Th, 230Th) and radium (228Th) isotopes. These three isotopes are radioactive and their half-lives vary from days (234Th) to years (228Th) to tens of thousands of years (230Th). Combining their known production […]
Feb / 07 / 2019
Helium-3 plumes in the deep Indian Ocean confirm hydrothermal activity
Thanks to samples collected as part of the Japanese GEOTRACES cruise in 2009 – 2010, along section GI04, Takahata and co-workers (2018, see reference below) identified a maximum helium-3 ratios value (δ3He >14%) at mid-depth (2000 – 3000 m) in the northern part (north of 30°S) of the central Indian Ocean, whereas lower ratio was […]
Oct / 23 / 2018
When hydrothermal iron fertilizes the surface ocean in the Western Tropical South Pacific Ocean
For the first time, iron measurements in the Western Tropical South Pacific reveal that shallow hydrothermal inputs from the Tonga Arc region fertilize the euphotic waters of this vast region. These results shed new light on the functioning of pelagic ecosystems in this region. Indeed, blooms in this area are dominated by N2-fixing organisms (or diazotrophs), […]
Jun / 18 / 2018
Low iron sulfide precipitation rate in hydrothermal fluids during the early stage of mixing
Waeles and co-authors (2017, see reference below) report for the first time on the dissolved-particulate partition of iron (Fe) after in situ filtration at the early stage of mixing of hydrothermal fluids with seawater. This study was performed at three hydrothermal fields on the Mid-Atlantic Ridge (Lucky Strike, TAG and Snakepit). For the different vents […]
May / 29 / 2017
What controls hydrothermal plume transport of iron over 4000 km in the deep Pacific Ocean?
The striking extension of the dissolved iron and manganese plumes over more than 4000 km from their hydrothermal sources along the US GEOTRACES East Pacific Zonal Transect (EPZT) cruise (GP16) has challenged our understanding of these element cycles (Resing et al., 2015 see GEOTRACES science highlight). Fitzsimmons and co-workers (2017, see reference below) analysed the particulate […]
Mar / 23 / 2017
What constrains the hydrothermal dissolved iron isotopic signatures?
Assessing the processes leading to dissolved iron (dFe) isotope fractionation in a hydrothermal plume is a key question, because it allows a better characterization of this specific source of dFe in the deep ocean. For the first time, Fe isotope composition of dissolved and total dissolvable Fe fractions was determined and compared to the bulk […]
Feb / 21 / 2017