摘要
Water quality data from 1981 to 2015 were used to elucidate the spatiotemporal distributions of chlorophyll a (Chl.a) concentration and Secchi depth in the west-central Seto Inland Sea, Japan. The results revealed that salinity and distance from the northern coastline were the main factors for predicting Chl.a concentration and Secchi depth, respectively. Significant differences in both of these were observed between subareas in spring, summer and autumn; differences were insignificant in winter. Chl.a concentrations have decreased for the past 35 years, while their extent differed in the subareas. A greater rate of decrease in Chl.a concentration was observed in the innermost Hiroshima Bay in spring, compared with other subareas, while no significant difference in different subareas was found in other seasons. Secchi depth has increased for the past 35 years, but no significant difference in its rate of increase was found among different subareas in all seasons. Total nitrogen loading better explained changes in mean Chl.a concentration than total phosphorus throughout the west-central Seto Inland Sea. Phytoplankton's contributions to light attenuation were low in the west-central Seto Inland Sea, indicating that the nutrient loading reduction programme has been of limited effectiveness in improving water clarity.
摘要译文
1981年至2015年的水质数据用于阐明日本濑户内海中西部叶绿素a（Chl.a）浓度和Secchi深度的时空分布。结果表明，盐度和距离北部海岸线的距离分别是预测Chl.a浓度和Secchi深度的主要因素。在春季，夏季和秋季的子区域之间观察到这两者的显着差异;冬天的差异微不足道。在过去的35年中，Chl.a浓度有所下降，而在子区域中它们的程度不同。与其他子区域相比，春季最内侧广岛湾的Chl.a浓度下降幅度更大，而其他季节的不同子区域没有显着差异。 Secchi深度在过去35年中有所增加，但在所有季节的不同子区域中，其增长率没有显着差异。总氮负荷更好地解释了平均Chl.a浓度的变化，而不是整个中西部濑户内海的总磷。在濑户内海中西部，浮游植物对光衰减的贡献较低，表明营养物负荷减少计划在提高水的透明度方面效果有限。
Feng Wang[1];Akira Umehara[2];Satoshi Nakai[1];Wataru Nishijima[2]. Management of the west-central Seto Inland Sea, Japan: factors controlling the spatiotemporal distributions of chlorophyll a concentration and Secchi depth[J]. Water Policy, 2019,21(4)