Arctic river dissolved and biogenic silicon exports - current conditions and future changes with warming

• Main Author: Carey, Joanna
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2020
• Subjects: biogenic silica; dissolved silica; Permafrost; permafrost; Phytoplankton; Alaska
• Online Access: https://doi.org/10.5061/dryad.7sqv9s4pp

Silicon (Si) exports from terrestrial to marine systems can dictate phytoplankton species composition in Arctic coastal waters. Diatoms are often the dominant autotroph in Arctic waters, making Si an important control on Arctic marine primary productivity. Yet, even as Arctic regions are among the fastest warming on Earth, we lack baseline knowledge on the magnitudes and controls of Arctic river Si exports. To address uncertainties in current and future Si behavior, we used a combination of field data and modeling to quantify daily yields of dissolved Si (DSi) and biogenic Si (BSi) from a 400 km space‐for‐time latitudinal gradient of seven basins across the boreal‐Arctic transition in Alaska (USA) over the course of two years (2015‐2016). Mean annual DSi concentrations (33‐149 μM) and yields (13‐49 kmol km ‐2 yr ‐1 ) were significantly and positively correlated with mean basin active layer depth, indicating that permafrost thaw will likely increase DSi fluxes to Arctic coastal waters. Conversely, BSi concentrations (7‐16 μM) and yields (2.6‐4.5 kmol km ‐2 yr ‐1 ) were more uniform across the seven basins, indicating that warming may not substantially alter BSi loads to coastal systems in the near future. Our data also indicate that climatic warming will advance the timing of Si delivery to coastal waters in the spring, although the ratios of Si to nitrogen in Arctic river exports will likely remain steady. These results highlight the important role of basin hydrology, largely driven by permafrost extent, as a key driver of Si exchange at the land‐sea interface in the Arctic. Data includes concentration (units in micromolar, also indicated in spreadsheet) and flow data (area-normalized water yields in cubic meters per hour per square kilometer). Any missing cells or 'NA's means that no data available for that sample. Funding provided by: National Science Foundation Crossref Funder Registry ID: http://dx.doi.org/10.13039/100000001 Award Number: 1451527