Hou Pengfei

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Hou
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Pengfei
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  • Article
    Climate control on terrestrial biospheric carbon turnover
    (National Academy of Sciences, 2021-02-23) Eglinton, Timothy I. ; Galy, Valier ; Hemingway, Jordon D. ; Feng, Xiaojuan ; Bao, Hongyan ; Blattmann, Thomas M. ; Dickens, Angela F. ; Gies, Hannah ; Giosan, Liviu ; Haghipour, Negar ; Hou, Pengfei ; Lupker, Maarten ; McIntyre, Cameron P. ; Montlucon, Daniel B. ; Peucker-Ehrenbrink, Bernhard ; Ponton, Camilo ; Schefuß, Enno ; Schwab, Melissa S. ; Voss, Britta M. ; Wacker, Lukas ; Wu, Ying ; Zhao, Meixun
    Terrestrial vegetation and soils hold three times more carbon than the atmosphere. Much debate concerns how anthropogenic activity will perturb these surface reservoirs, potentially exacerbating ongoing changes to the climate system. Uncertainties specifically persist in extrapolating point-source observations to ecosystem-scale budgets and fluxes, which require consideration of vertical and lateral processes on multiple temporal and spatial scales. To explore controls on organic carbon (OC) turnover at the river basin scale, we present radiocarbon (14C) ages on two groups of molecular tracers of plant-derived carbon—leaf-wax lipids and lignin phenols—from a globally distributed suite of rivers. We find significant negative relationships between the 14C age of these biomarkers and mean annual temperature and precipitation. Moreover, riverine biospheric-carbon ages scale proportionally with basin-wide soil carbon turnover times and soil 14C ages, implicating OC cycling within soils as a primary control on exported biomarker ages and revealing a broad distribution of soil OC reactivities. The ubiquitous occurrence of a long-lived soil OC pool suggests soil OC is globally vulnerable to perturbations by future temperature and precipitation increase. Scaling of riverine biospheric-carbon ages with soil OC turnover shows the former can constrain the sensitivity of carbon dynamics to environmental controls on broad spatial scales. Extracting this information from fluvially dominated sedimentary sequences may inform past variations in soil OC turnover in response to anthropogenic and/or climate perturbations. In turn, monitoring riverine OC composition may help detect future climate-change–induced perturbations of soil OC turnover and stocks.
  • Article
    Unraveling Environmental Forces Shaping Surface Sediment Geochemical “Isodrapes” in the East Asian Marginal Seas
    (American Geophysical Union, 2024-04-04) Paradis, Sarah ; Diesing, Markus ; Gies, Hannah ; Haghipour, Negar ; Narman, Lena ; Magill, Clayton ; Wagner, Thomas ; Galy, Valier V. ; Hou, Pengfei ; Zhao, Meixun ; Kim, Jung-Hyun ; Shin, Kyung-Hoon ; Lin, Baozhi ; Liu, Zhifei ; Wiesner, Martin G. ; Stattegger, Karl ; Chen, Jianfang ; Zhang, Jingjing ; Eglinton, Timothy I.
    As major sites of carbon burial and remineralization, continental margins are key components of the global carbon cycle. However, heterogeneous sources of organic matter (OM) and depositional environments lead to complex spatial patterns in sedimentary organic carbon (OC) content and composition. To better constrain the processes that control OM cycling, we focus on the East Asian marginal seas as a model system, where we compiled extensive data on the OC content, bulk isotopic composition (δ13C and Δ14C), total nitrogen, and mineral surface area of surficial sediments from previous studies and new measurements. We developed a spatial machine learning modeling framework to predict the spatial distribution of these parameters and identify regions where sediments with similar geochemical signatures drape the seafloor (i.e., “isodrapes”). We demonstrate that both provenance (44%–77%) and hydrodynamic processes (22%–53%) govern the fate of OM in this margin. Hydrodynamic processes can either promote the degradation of OM in mobile mud-belts or preserve it in stable mud-deposits. The distinct isotopic composition of OC sources from marine productivity and individual rivers regulates the age and reactivity of OM deposited on the sea-floor. The East Asian marginal seas can be separated into three main isodrapes: hydrodynamically energetic shelves with coarser-grained sediment depleted in OC, OM-enriched mud deposits, and a deep basin with fine-grained sediments and aged OC affected by long oxygen exposure times and petrogenic input from rivers. This study confirms that both hydrodynamic processes and provenance should be accounted for to understand the fate of OC in continental margins.