New revelations on boundary scavenging in the North Pacific

Thorium (Th) and protactinium (Pa) are very efficient tracers of particle dynamics in the ocean. More particularly, their relative distributions inform on the intensity of “scavenging”, in other words, the processes that remove dissolved elements from seawater by their precipitation or adsorption on particles. Thanks to 12 new profiles in the North Pacific, Hayes and co-authors observe a much larger relative difference in scavenging intensity between the Subtropical gyre and Subarctic Pacific gyre than within each of these regions. This effect is greater for Pa than for Th, likely reflecting the fact that biogenic silica, a phase produced by diatoms which has a strong affinity for Pa, is much more prevalent in the North. While highlighting the role of biogeography, the study also finds that in the deep ocean, manganese oxides, an inorganic phase, may play an additional role in Pa scavenging.

13 Hayes l

Figure: Simplified figure showing scavenging intensity in the Pacific Ocean.
Please click here to view the figure larger.

 

Reference:

Hayes, C. T., Anderson, R. F., Jaccard, S. L., François, R., Fleisher, M. Q., Soon, M., & Gersonde, R. (2013). A new perspective on boundary scavenging in the North Pacific Ocean. Earth and Planetary Science Letters, 369-370, 86–97. doi:10.1016/j.epsl.2013.03.008. Click here to access the paper.

Latest highlights

Science Highlights

Thorium-Protactinium fate across the tropical Atlantic Ocean: what reveals the water column-sediment coupling

Twenty seawater profiles and twenty core-top 231-protactinium and 230-thorium analyses were realised by Ng and colleagues along five depth transects across the northern tropical Atlantic open ocean.

18.01.2021

Science Highlights

Constraining Oceanic Copper Cycling through Artificial Intelligence and Ocean Circulation Inverse Model

Using available observations of dissolved copper, artificial neural networks, and an ocean circulation inverse model, authors calculated a global estimate of the 3-dimensional distribution and cycling of dissolved copper in the ocean

15.01.2021

Science Highlights

Particulate rare earth elements distributions, processes and characterisation of nepheloids in the North Atlantic

Lagarde et al. realised the first basin scale section of particulate rare earth elements concentrations across the North Atlantic Ocean.

06.01.2021

Science Highlights

Isopycnal mixing controls protactinium and thorium distributions in the Pacific Southern Ocean

Pavia and co-workers determined the physical and chemical speciation as well as the vertical distribution of Protactinium-231 and Thorium-230 at 12 stations across the Southern Pacific Antarctic Circumpolar Current…

13.12.2020

Rechercher