Biogeochemistry of Trace Elements and Their Isotopes in the subarctic North Pacific Ocean and the Gulf of Alaska (GEOTRACES GP-02 line included).
This cruise aimed at establishing the 2-dimensional profiles of GEOTRACES TEIs in the subarctic Pacific, in order to advance ocean sciences on TEIs as mentioned above. The northern North Pacific is known as a typical High Nutrient, Low Chlorophyll (HNLC) zone. Some radioisotopes were partially released to this oceanic area with the accident at Fukushima nuclear power plant on March 11, 2011. In this important area, we had conducted a similar cruise by R/V HAKUHO MARU (KH-12-4) in 2012 for the zonal line along 47°N (GP02), and finished the line observations in the western and central subarctic Pacific. Unfortunately, however, we could not finish the zonal line in eastern subarctic Pacific because of stormy weather condition. During this cruise, we completed the zonal line observations along 47°N (GP02), especially in the eastern subarctic Pacific. Since we revisited the several stations in the western subarctic Pacific stations overlapping the previous stations during KH-12-4 cruise, it may be interesting to compare the data obtained this time with those in the past, revealing temporal changes in various physical, chemical and biological parameters in the western Pacific. One more important target of the cruise is to study the present and past status of TEIs in seawaters of the Gulf of Alaska, which is also a typical HNLC area. We set 2-dimensional section observations along 145°W to investigate TEIs in seawaters and sediments of Gulf of Alaska. It will be interesting to compare biogeochemical cycles of TEIs in the western subarctic Pacific with those in the Gulf of Alaska.
Hajime Obata (University of Tokyo, Atmosphere and Ocean Research Institute)
GEOTRACES -Trace elements and their isotopes in the water column