La mer
Online ISSN : 2434-2882
Print ISSN : 0503-1540
Volume 53, Issue 1-2
Displaying 1-3 of 3 articles from this issue
  • Iwao TANITA, Shigenobu TAKEDA, Mitsuhide SATO, Ken FURUYA
    2015 Volume 53 Issue 1-2 Pages 1-18
    Published: 2015
    Released on J-STAGE: May 22, 2022
    JOURNAL OPEN ACCESS
    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.
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  • Tsuyoshi FUKAO, Toshimasa ASAHI, Kuninao TADA
    2015 Volume 53 Issue 1-2 Pages 19-27
    Published: 2015
    Released on J-STAGE: May 22, 2022
    JOURNAL OPEN ACCESS
    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 environments.
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  • Motoaki KISHINO, Ken FURUYA
    2015 Volume 53 Issue 1-2 Pages 29-38
    Published: 2015
    Released on J-STAGE: May 22, 2022
    JOURNAL OPEN ACCESS
    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.
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