Vertical distributions of dissolved copper were investigated at two stations in the
western subarctic and tropical North Pacific to elucidate the factors controlling its concentration.
There was a significant correlation (p-value < 0.05) at the subarctic and tropical stations between
dissolved copper and silicic acid between 400-3000 m and 300-2000 m depths, respectively, which
implies the importance of diatoms in transporting copper. The dissolved copper concentration at
depths shallower than 1000 m was 1.3-2.7 times higher at the subarctic station than that at the
tropical station, and at depths shallower than 1500 m, it was 0.97-2.60 nM higher at the subarctic
station than the average of other reported values of the North Pacific. This can be attributed to
several processes. In the surface layer, horizontal advection of the coastal water by the East
Kamchatka Current was considered to be a source of copper because a high concentration was
observed within low-salinity surface waters. Supply of copper below the surface layer to 1500 m
was probably owing to downward transport by the biological pump and horizontal advection.
These results suggest that horizontal transport of copper from coastal or shelf area is important
for biological production and Cu distribution in this region.
The changes of salp abundance and environmental factors such as water temperature
and salinity were investigated in surface water of Shitaba Bay, Uwa Sea, Japan, in spring, 2011.
Furthermore, sediment trap samples were collected at the bottom ocean layer of Shitaba Bay
during salp bloom phase or non-bloom phase. Maximum salp abundance were recorded at 26
April, but no salp were observed at water temperatures of more than 20℃ (from 12 May
onwards). Particulate organic carbon and nitrogen fluxes during salp bloom phase were higher
than those during non-bloom phase. Therefore, these results showed that salp bloom in spring
contributed to rapid supply of particulate organic matter from surface to bottom layer in coastal
A new simplified method to measure water-leaving radiance was developed by
combined use of a miniature spectrophotometer, a collimator, and a narrow pipe to block reflected
sunlight from the sea surface. The instrument was handy, light-weighted and least expensive
compared with those available for commercial use. The water-leaving radiance was determined
by using the above-mentioned setup in the East China Sea, the Seto Inland Sea, and Shonai-ko of
Lake Hamana. These areas covered a wide range of water mass types from clear to turbid water,
and the new method was successfully implemented in all the areas. Signal to noise ratios of remote
sensing reflectance Rrs measured by the instrument were satisfactorily small by taking running
mean of 7 data readings over about 1.3 nm and by sampling of 1 nm interval. However, noises
were not negligible in a low Rrs range below 0.001 sr
-1 which occurred in the longer wavelength
range than 650 nm. The estimated errors due to self-shading were satisfactorily small (< 5%) in
the wavelength range from 400 to 590 nm.