title: Importance of Oceanian small mountainous rivers (SMRs) in global land-to-ocean output of lignin and modern biospheric carbon.
abstract: The land-to-ocean export of particulate organic carbon (POC) connects carbon flow from the atmosphere through land to the ocean, of which the contemporary fraction that reaches the deep sea for burial may effectively affect atmospheric CO2. In this regard, small mountainous rivers (SMRs) in Oceania, a global erosion hotspot driven by torrential typhoon rain and active earthquakes are potentially important. Here we measured typhoon lignin discharges for Taiwan SMRs. We found that the particulate lignin export in 96 hours by a single SMR amounting to ~20% of the annual export by Mississippi River. The yearly particulate lignin discharge from Taiwan Island (35,980 km(2)) is governed by the frequency and magnitude of typhoon; thus, the historical lignin export ranged widely from 1.5 to 99.7 Gg yr(-1), which resulted in a 10-100 times higher areal yield relative to non-Oceanian rivers. The lignin-derived modern POC output from Oceania region is 37 ± 21 Tg C yr(-1), account for approximately 20% of the annual modern POC export from global rivers. Coupled with the hyperpycnal pathway, the forested watersheds of SMRs in Oceania may serve as a giant factory to rapidly produce and efficiently convey modern POC into deep sea for sequestration.
authors.affiliation: State Key Laboratory of Marine Environmental Science, Xiamen University, 361102, Xiamen, China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Bao
authors.affiliation: Department of Geography, National Taiwan Normal University, Taipei, Taiwan.
authors.forename: Tsung-Yu
authors.initials: TY
authors.lastname: Lee
authors.affiliation: Department of Geography, National Taiwan University, Taipei, Taiwan.
authors.forename: Jr-Chuan
authors.initials: JC
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Marine Environmental Science, Xiamen University, 361102, Xiamen, China.
authors.forename: Minhan
authors.initials: M
authors.lastname: Dai
authors.affiliation: State Key Laboratory of Marine Environmental Science, Xiamen University, 361102, Xiamen, China.
authors.forename: Shuh-Ji
authors.initials: SJ
authors.lastname: Kao