Arctic Ocean

Figure 1. Map showing the sampling stations 30, 43, 48 and 56 in the US Arctic GEOTRACES (GN01) section. Water samples for dissolved and particulate 210Po and 210Pb were collected onboard US Coast Guard Cutter Healy (HLY1502) from August 9th to October 11th, 2015. The arrows represent the major circulation pattern of the surface layer water mass. The map was created using Ocean Data View 5.2.0.

The Arctic Ocean is undergoing dramatic changes in freshwater input and particle concentration/composition. Thus it important for us to understand how 210Po-210Pb disequilibria which is often used as a proxy for particle scavenging and POC export in the ocean is influenced by the suspended particle composition in the western Arctic Ocean. Our results showed that both the particle concentration and composition influence the distribution of 210Po and 210Pb, however the particle composition seems to influence 210Po more than 210Pb. Using the major phases Kd(Po) and Kd(Pb) in the end member mixing model, we calculated the predicted bulk partition coefficient and found the Kd(Po) and Kd(Pb) were within the range of observed Kd values. Interestingly we find the partition coefficient of Po and Pb to be higher in Arctic compare to the Atlantic and Pacific Ocean for a similar range of suspended particulate materials, which we attribute to higher concentration of Mn in the Arctic Ocean.