Surface seawater was collected for ^(226)Ra measurement in the North Pacific Subtropical Gyre from July to October, 1999 and October to December, 2003. Combined with the historical data reported for this sea area, a ...Surface seawater was collected for ^(226)Ra measurement in the North Pacific Subtropical Gyre from July to October, 1999 and October to December, 2003. Combined with the historical data reported for this sea area, a declined trend of surface ^(226)Ra concentrations was observed since 1960s, indicating the ecosystem shift in response to global warming. On one side, the enhanced stratification of the upper water column resulting from global warming reduced the ^(226)Ra input from the depth, on the other, the temporal increase of biological production resulting from the climate-related ecosystem structure change strengthened the ^(226)Ra removal from the surface ocean. Both the physical and biological processes resulted in the decrease of surface ^(226)Ra concentrations in the North Pacific Subtropical Gyre. The temporal trend of surface ^(226)Ra concentrations was consistent with the trends of chlorophyll a, silicate, phosphate and primary production previously reported. This study provided ^(226)Ra evidence for the ecosystem shift under global change.展开更多
基金Supported by the National Natural Science Foundation of China (Grant No. 90411016)the National Key Basic Research Special Foundation Program of China (Grant No. 2005CB422305)China Ocean Mineral Resources R& D Association Foundation (Grant Nos. DY105-02-04 and DY105-02-01)
文摘Surface seawater was collected for ^(226)Ra measurement in the North Pacific Subtropical Gyre from July to October, 1999 and October to December, 2003. Combined with the historical data reported for this sea area, a declined trend of surface ^(226)Ra concentrations was observed since 1960s, indicating the ecosystem shift in response to global warming. On one side, the enhanced stratification of the upper water column resulting from global warming reduced the ^(226)Ra input from the depth, on the other, the temporal increase of biological production resulting from the climate-related ecosystem structure change strengthened the ^(226)Ra removal from the surface ocean. Both the physical and biological processes resulted in the decrease of surface ^(226)Ra concentrations in the North Pacific Subtropical Gyre. The temporal trend of surface ^(226)Ra concentrations was consistent with the trends of chlorophyll a, silicate, phosphate and primary production previously reported. This study provided ^(226)Ra evidence for the ecosystem shift under global change.
