Long-Term Changes in Concentration and Yield of Riverine Dissolved Silicon From the Poles to the Tropics

TitleLong-Term Changes in Concentration and Yield of Riverine Dissolved Silicon From the Poles to the Tropics
Publication TypeJournal Article
Year of Publication2023
AuthorsJankowski KJo, Johnson K, Sethna L, Julian P, Wymore AS, Shogren AJ, Thomas PK, Sullivan PL, McKnight DM, McDowell WH, Heindel R, Jones JB, Wollheim W, Abbott B, Deegan L, Carey JC
JournalGlobal Biogeochemical Cycles
Volume37
Paginatione2022GB007678
ISSN1944-9224
Keywordsand modeling; biogeochemical cycles; biogeochemistry; hydrologic time series analysis; impacts of global change; nutrients and nutrient cycling; processes; river; silica; trends
Abstract

Riverine exports of silicon (Si) influence global carbon cycling through the growth of marine diatoms, which account for ∼25% of global primary production. Climate change will likely alter river Si exports in biome-specific ways due to interacting shifts in chemical weathering rates, hydrologic connectivity, and metabolic processes in aquatic and terrestrial systems. Nonetheless, factors driving long-term changes in Si exports remain unexplored at local, regional, and global scales. We evaluated how concentrations and yields of dissolved Si (DSi) changed over the last several decades of rapid climate warming using long-term data sets from 60 rivers and streams spanning the globe (e.g., Antarctic, tropical, temperate, boreal, alpine, Arctic systems). We show that widespread changes in river DSi concentration and yield have occurred, with the most substantial shifts occurring in alpine and polar regions. The magnitude and direction of trends varied within and among biomes, were most strongly associated with differences in land cover, and were often independent of changes in river discharge. These findings indicate that there are likely diverse mechanisms driving change in river Si biogeochemistry that span the land-water interface, which may include glacial melt, changes in terrestrial vegetation, and river productivity. Finally, trends were often stronger in months outside of the growing season, particularly in temperate and boreal systems, demonstrating a potentially important role of shifting seasonality for the flux of Si from rivers. Our results have implications for the timing and magnitude of silica processing in rivers and its delivery to global oceans.

URLhttps://onlinelibrary.wiley.com/doi/abs/10.1029/2022GB007678
DOI10.1029/2022GB007678
Citation Keyjankowski_long-term_2023