title: Residual β activity of particulate (234)Th as a novel proxy for tracking sediment resuspension in the ocean.
abstract: Sediment resuspension occurs in the global ocean, which greatly affects material exchange between the sediment and the overlying seawater. The behaviours of carbon, nutrients, heavy metals, and other pollutants at the sediment-seawater boundary will further link to climate change, eutrophication, and marine pollution. Residual β activity of particulate (234)Th (RAP234) is used as a novel proxy to track sediment resuspension in different marine environments, including the western Arctic Ocean, the South China Sea, and the Southern Ocean. Sediment resuspension identified by high activity of RAP234 is supported by different lines of evidence including seawater turbidity, residence time of total (234)Th, Goldschmidt's classification, and ratio of RAP234 to particulate organic carbon. A conceptual model is proposed to elucidate the mechanism for RAP234 with dominant contributions from (234)Th-(238)U and (212)Bi-(228)Th. The 'slope assumption' for RAP234 indicated increasing intensity of sediment resuspension from spring to autumn under the influence of the East Asian monsoon system. RAP234 can shed new light on (234)Th-based particle dynamics and should benefit the interpretation of historical (234)Th-(238)U database. RAP234 resembles lithophile elements and has broad implications for investigating particle dynamics in the estuary-shelf-slope-ocean continuum and linkage of the atmosphere-ocean-sediment system.
authors.affiliation: School of Marine Science, Guangxi University, Nanning, China.
authors.forename: Wuhui
authors.initials: W
authors.lastname: Lin
authors.affiliation: Key Laboratory of Global Change and Marine-Atmospheric Chemistry, Third Institute of Oceanography, State Oceanic Administration, Xiamen, China.
authors.forename: Liqi
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Engineering Physics, Tsinghua University, Beijing, China.
authors.forename: Shi
authors.initials: S
authors.lastname: Zeng
authors.affiliation: Ocean University of China, Qingdao, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.affiliation: School of Marine Science, Guangxi University, Nanning, China.
authors.forename: Yinghui
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Marine Science, Guangxi University, Nanning, China.
authors.forename: Kefu
authors.initials: K
authors.lastname: Yu