Decadal Shifts in High Latitude River Silicon Stoichiometry across Continents

High latitude systems are warming at a faster rate that the global average, altering rates of silicon (Si) mobilization from terrestrial to aquatic systems. Aquatic dissolved Si availability and its ratio with other nutrients exert strong control on seasonal algae blooms in freshwater and downstream marine receiving waters, especially in high latitude systems where diatoms are often the dominant autotroph. Here we present an examination of long-term (~20 years) changes of daily river dissolved Si concentrations, loads, and nutrient ratios in >60 rivers spanning high latitude systems in North America, Europe, Asia, and Antarctica. We examined changes in Si on seasonal and annual scales, and with respect to dissolved inorganic nitrogen and phosphorus availability. We find a predominant trend of increasing dissolved Si concentrations, and declining N and P concentrations, ultimately leading to increased loads of Si relative to N and P. We also find that concentrations are changing to a much larger degree than discharge over time. Our analysis demonstrates that trends in high latitude riverine Si varied through space (i.e. across continents) and time (i.e. seasonally) and differed from trends in other nutrients, which has implications for seasonal diatom blooms in high latitude fresh and marine waters.

Primary Presenter: Joanna Carey, Babson College (jcarey@babson.edu)

Authors:

Nick Lyon, NCEAS  (lyon@nceas.ucsb.edu)

Keira Johnson, OSU  (johnkeir@oregonstate.edu)

Pirkko Kortelainen, Finnish Environmental Institute  (pirkko.kortelainen@syke.fi)

Pamela Sullivan, OSU  (Pamela.Sullivan@oregonstate.edu)

Hjalmar Laudon, Swedish University of Agricultural Sciences  (Hjalmar.Laudon@slu.se)

Amanda Poste, Norwegian Institute for Nature Research  (amanda.poste@nina.no)

Diane McKnight, CSU  (Diane.Mcknight@colorado.edu)

Ruth Heindel, Kenyon College  (Heindel1@kenyon.edu)

Arial Shogren, UA  (ashogren@ua.edu)

Lienne Sethna, St. Croix Watershed Research Station  (lsethna@smm.org)

Kathi Jo Jankowski, USGS  (kjankowski@usgs.gov)