Processes influencing iron distribution in the coastal waters of the Tsugaru Strait,Japan |
| |
Authors: | Yukiyo Saitoh Kenshi Kuma Yutaka Isoda Hiroshi Kuroda Hiromi Matsuura Taku Wagawa Hyoe Takata Naoto Kobayashi Seiya Nagao Takeshi Nakatsuka |
| |
Institution: | (1) Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, 041-8611 Hokkaido, Japan;(2) Graduate School of Environmental Science, Hokkaido University, North 13 West 8, Kita-Ku, Sapporo, 060-0813 Hokkaido, Japan; |
| |
Abstract: | We report measurements of iron, nutrients, dissolved oxygen, humic-type fluorescence intensity and chlorophyll a concentrations in the coastal waters at the inflow (western) and outflow (eastern) ends of Tsugaru Strait (Japan) in June
2003 and 2004. Two different water masses (intensive eastward flow “subtropical Tsugaru Warm Current Water (TWCw)” and weak
westward flow “subarctic Oyashio Water (OW)”) were observed at the eastern end of the strait. TWCw at the southern part of
the eastern strait was vertically homogeneous with a uniform concentrations of iron (0.7–1.1 nM for labile dissolved Fe and
14–20 nM for total dissolvable Fe in 2003) as well as other chemical, biological and physical components throughout the water
column of 200 m due to strong vertical mixing in the strait. The degree of mixing in the Tsugaru Warm Current (TWC) is predominantly
affected by diurnal tidal current, which is strong during the period of tropical tides and weak during the period of equinoctial
ones. The especially strong vertical water mixing in 2003 is caused by large dissipation energy input due to the bottom friction
of passage-flow through the strait and tidal current. At the northern part of the eastern strait, the fresh surface layer
overlying the OW and the deep-bottom waters in 2003 contained large concentrations of dissolved iron, resulting from iron
supplied from river runoff and shelf sediments, respectively. These results suggest that the most important mechanism for
transporting iron in the strait is the strong vertical water mixing due to the tidal current, and that the iron sources in
the coastal waters are the organic-associated, iron-rich freshwater input into the surface water. |
| |
Keywords: | Iron input nitrate AOU tidal mixing coastal waters Tsugaru Strait |
本文献已被 SpringerLink 等数据库收录! |
|