Riverine concentrations and export of dissolved silicon, and potential controls on nutrient stoichiometry, across the land–ocean continuum in Great Britain

• DOI: 10.1016/j.jhydrol.2024.131738
• Publication Date: 2024-07-31T06:39:45Z
• Authors: Andrew M. Tye; Helen P. Jarvie; Bryan M. Spears; Nancy B. Dise; Jennifer L. Willi...; Dan J. Lapworth; Don Monteith; Richard Sanders; Daniel J. Mayor; Michael J. Bowes; Michael Bowes; Annette Burden; Nathan Callaghan; Gareth Farr; Stacey Felgate; Stuart Gibb; Pete Gilbert; Geoff Hargreaves; Olivier S. Humphrey; Patrick Keenan; Vassilis Kitidis; Monika D. Jürgens; Adrian Martin; Monty Pearson; Philip D. Nightin...; M. Gloria Pereira; Justyna Olszewska; Amy Pickard; Andrew P. Rees; Mark Stinchcombe; Fred Worrall; Chris D. Evans
• Keywords: Dissolved silica

Silicon (Si) is an essential nutrient element in freshwater and marine ecosystems, its abundance relative to macro-nutrients (N, P) can impact phytoplankton communities eutrophic rivers estuaries. This study the first national assessment examining (i) primary sources (geological, biological, landcover) controls (geomorphological, precipitation) on transport of terrestrial dissolved silicon across Great Britain ocean, (ii) current extent nature interactions with these catchments relation potential impacts community structure. It uses results from a year-long survey 41 along historical data. Highest concentrations Si (4–5.5 mg L-1) were found chalk- sedimentary sandstone-based southern hard sandstone Scotland. Catchment yield rates for varied between 0.2 2.6 t km−2 yr−1, highest yields higher precipitation runoff. Analysis river N:P Si:N ratios suggested that sampled typically N enriched, P limited respect Si. Molar < 1, indicator eutrophication, associated total nitrogen exceeding 1.8 L-1 or greater. The Indicator Coastal Eutrophication index was used assess role eutrophication coastal waters. Negative values indicating non-siliceous algae generally found, although some had annual 0, as high 35 kg C day−1. In many rivers, derived catchment lithology, kept below zero. Results have demonstrated export likely shifted most waters beyond stoichiometric range where diatoms dominate production into one maybe increasingly present. Thus, future assessments macro-nutrient management schemes, such those involving wetlands should include routinely due importance.