Woods Hole Oceanographic Institution

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The Woods Hole Oceanographic Institution is a private, independent, not-for-profit corporation dedicated to research and higher education at the frontiers of ocean science.

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Browsing Woods Hole Oceanographic Institution by Author "Achterberg, Eric P."
  • Article
    Authigenic Formation of Clay Minerals in the Abyssal North Pacific
    (American Geophysical Union, 2022-11-02) Steiner, Zvi ; Rae, James W. B. ; Berelson, William M. ; Adkins, Jess F. ; Hou, Yi ; Dong, Sijia ; Lampronti, Giulio I. ; Liu, Xuewu ; Achterberg, Eric P. ; Subhas, Adam V. ; Turchyn, Alexandra V.
    Present estimates of the biogeochemical cycles of calcium, strontium, and potassium in the ocean reveal large imbalances between known input and output fluxes. Using pore fluid, incubation, and solid sediment data from North Pacific multi‐corer cores we show that, contrary to the common paradigm, the top centimeters of abyssal sediments can be an active site of authigenic precipitation of clay minerals. In this region, clay authigenesis is the dominant sink for potassium and strontium and consumes nearly all calcium released from benthic dissolution of calcium carbonates. These observations support the idea that clay authigenesis occurring over broad regions of the world ocean may be a major buffer for ocean chemistry on the time scale of the ocean overturning circulation, and key to the long‐term stability of Earth's climate.Key PointsNorth Pacific red clay sediments are a sink for marine calcium, strontium, and potassiumAuthigenic formation of clay minerals is prevalent in pelagic sediments throughout the North PacificThe main mechanism for clay formation is recrystallization of aluminosilicates, neoformation can occur in biogenic silica rich sediments
  • Article
    Persistent equatorial Pacific iron limitation under ENSO forcing
    (Nature Research, 2023-08-16) Browning, Thomas J. ; Saito, Mak A. ; Garaba, Shungudzemwoyo P. ; Wang, Xuechao ; Achterberg, Eric P. ; Moore, C. Mark ; Engel, Anja ; Mcllvin, Matthew R. ; Moran, Dawn ; Voss, Daniela ; Zielinski, Oliver ; Tagliabue, Alessandro
    Projected responses of ocean net primary productivity to climate change are highly uncertain1. Models suggest that the climate sensitivity of phytoplankton nutrient limitation in the low-latitude Pacific Ocean plays a crucial role1,2,3, but this is poorly constrained by observations4. Here we show that changes in physical forcing drove coherent fluctuations in the strength of equatorial Pacific iron limitation through multiple El Niño/Southern Oscillation (ENSO) cycles, but that this was overestimated twofold by a state-of-the-art climate model. Our assessment was enabled by first using a combination of field nutrient-addition experiments, proteomics and above-water hyperspectral radiometry to show that phytoplankton physiological responses to iron limitation led to approximately threefold changes in chlorophyll-normalized phytoplankton fluorescence. We then exploited the >18-year satellite fluorescence record to quantify climate-induced nutrient limitation variability. Such synoptic constraints provide a powerful approach for benchmarking the realism of model projections of net primary productivity to climate changes.
  • Article
    Trace element geochemistry in North Pacific red clay sediment porewaters and implications for water‐column studies
    (American Geophysical Union, 2023-11-14) Steiner, Zvi ; Antler, Gilad ; Berelson, William M. ; Crockford, Peter W. ; Dunlea, Ann G. ; Hou, Yi ; Adkins, Jess F. ; Turchyn, Alexandra V. ; Achterberg, Eric P.
    Geochemical analyses of trace elements in the ocean water column have suggested that pelagic clay-rich sediments are a major source of various elements to bottom-waters. However, corresponding high-quality measurements of trace element concentrations in porewaters of pelagic clay-rich sediments are scarce, making it difficult to evaluate the contributions from benthic processes to global oceanic cycles of trace elements. To bridge this gap, we analyzed porewater and bulk sediment concentrations of vanadium, chromium, cobalt, nickel, copper, arsenic, molybdenum, barium and uranium, as well as concentrations of the major oxidants nitrate, manganese, iron, and sulfate in the top 30 cm of cores collected along a transect from Hawaii to Alaska. The data show large increases in porewater concentrations of vanadium, manganese, cobalt, nickel, copper, and arsenic within the top cm of the sediment, consistent with the release of these elements from remineralized organic matter. The sediments are a sink for sulfate, uranium, and molybdenum, even though conditions within the sampled top 30 cm remain aerobic. Porewater chromium concentrations generally increase with depth due to release from sediment particles. Extrapolated to the global aerial extent of pelagic clay sediment, the benthic fluxes in mol yr−1 are Ba 3.9 ± 3.6 × 109, Mn 3.4 ± 3.5 × 108, Co 2.6 ± 1.3 × 107, Ni 9.6 ± 8.6 × 108, Cu 4.6 ± 2.4 × 109, Cr 1.7 ± 1.1 × 108, As 6.1 ± 7.0 × 108, V 6.0 ± 2.5 × 109. With the exception of vanadium, calculated fluxes across the sediment–water interface are consistent with the variability in bottom-water concentrations and ocean residence time of the studied elements.