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

High levels of anthropogenic lead in the Indian Ocean

Yadav and her colleagues provide comprehensive insights into the distribution and sources of dissolved lead in the Indian Ocean.

Elevated methylmercury level in Arctic rain and aerosol linked to oceanic dimethylmercury emissions

He and colleagues highlight a previously underappreciated pathway of mercury transport, underscoring its significance to human health.

Unveiling the Complexity of Lead Distribution in the Pacific Ocean: Insights from the GEOTRACES GP15 Transect

This recent study by Jiang and colleagues investigates the distribution and sources of lead in the Pacific Ocean.

Organic matter export rates along a North-South Pacific Ocean section: what three estimating methods tell us

Quay and his colleagues present estimates of the organic matter export rate along the GEOTRACES GP15 cruise section.

Rechercher