资源环境科技发展态势分析平台

The vast area of the North Pacific subtropical gyre (NPSG) makes it an important region in exporting biogenic particles and carbon to the deep ocean. Nevertheless, we remain largely ignorant on its past changes in export productivity, leaving an important gap in the understanding of ocean-climate interactions during the late Quaternary. Here, we take a novel approach to study the particle export via reconstruction of dissolved(230)Th/Th-232 based on ferromanganese crusts in deep waters of the NPSG at 3.8- and 2.8-km water depth, respectively. The U-series data indicate stable growth rates of both samples and a rather small variability of their initial (Th-230/Th-232) in the last ca. 0.7 Myr. These glacial-interglacial integrated values are only about half of the modern dissolved (Th-230/Th-232) in the deep NPSG, reflecting increased dust dissolution and also particle scavenging related to similar to 10-40% higher average export productivity than today.