Rose Neil L.

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Rose
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Neil L.
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  • Preprint
    Increased accumulation of sulfur in lake sediments of the high Arctic
    ( 2010-08-31) Drevnick, Paul E. ; Muir, Derek C. G. ; Lamborg, Carl H. ; Horgan, Martin J. ; Canfield, Donald E. ; Boyle, John F. ; Rose, Neil L.
    We report a synchronous increase in accumulation of reduced inorganic sulfur since c. 1980 in sediment cores from eight of nine lakes studied in the Canadian Arctic and Svalbard (Norway). Sediment incubations and detailed analyses of sediment profiles from two of the lakes indicate that increases in sulfur accumulation may be due ultimately to a changing climate. Warming-induced lengthening of the ice-free season is resulting in well-documented increases in algal production and sedimentation of the resulting detrital matter. Algal detritus is a rich source of labile carbon, which in these sediments stimulates dissimilatory sulfate reduction. The sulfide produced is stored in sediment (as acid volatile sulfide), converted to other forms of sulfur, or reoxidized to sulfate and lost to the water column. An acceleration of the sulfur cycle in Arctic lakes could have profound effects on important biogeochemical processes, such as carbon burial and mercury methylation.
  • Preprint
    Net atmospheric mercury deposition to Svalbard : estimates from lacustrine sediments
    ( 2012-05) Drevnick, Paul E. ; Yang, Handong ; Lamborg, Carl H. ; Rose, Neil L.
    In this study we used lake sediments, which faithfully record Hg inputs, to derive estimates of net atmospheric Hg deposition to Svalbard, Norwegian Arctic. With the exception of one site affected by local pollution, the study lakes show twofold to fivefold increases in sedimentary Hg accumulation since 1850, likely due to long-range atmospheric transport and deposition of anthropogenic Hg. Sedimentary Hg accumulation in these lakes is a linear function of the ratio of catchment area to lake area, and we used this relationship to model net atmospheric Hg flux: preindustrial and modern estimates are 2.5±3.3 μg/m2/y and 7.0±3.0 μg/m2/y, respectively. The modern estimate, by comparison with data for Hg wet deposition, indicates that atmospheric mercury depletion events (AMDEs) or other dry deposition processes contribute approximately half (range 0-70%) of the net flux. Hg from AMDEs may be moving in significant quantities into aquatic ecosystems, where it is a concern because of contamination of aquatic food webs.
  • Article
    Exceptional 20th century ocean circulation in the Northeast Atlantic
    (American Geophysical Union, 2020-04-17) Spooner, Peter T. ; Thornalley, David J. R. ; Oppo, Delia W. ; Fox, Alan D. ; Radionovskaya, Svetlana ; Rose, Neil L. ; Mallett, Robbie ; Cooper, Emma ; Roberts, J. Murray
    The North Atlantic subpolar gyre (SPG) connects tropical and high‐latitude waters, playing a leading role in deep‐water formation, propagation of Atlantic water into the Arctic, and as habitat for many ecosystems. Instrumental records spanning recent decades document significant decadal variability in SPG circulation, with associated hydrographic and ecological changes. Emerging longer‐term records provide circumstantial evidence that the North Atlantic also experienced centennial trends during the 20th century. Here, we use marine sediment records to show that there has been a long‐term change in SPG circulation during the industrial era, largely during the 20th century. Moreover, we show that the shift and late 20th century SPG configuration were unprecedented in the last 10,000 years. Recent SPG dynamics resulted in an expansion of subtropical ecosystems into new habitats and likely also altered the transport of heat to high latitudes.