This dataset includes average, and annual average (e.g., average of 2020) watershed characteristics and environmental driver data for 189 rivers across the Northern Hemisphere. Average data includes lithology (e.g., percent of watershed covered by volcanics), land use (e.g., percent of watershed covered by cropland), maximum day length, median nitrogen and phosphorus concentrations, maximum watershed proportion of snow covered area, precipitation, temperature, evapotranspiration, green-up day, net primary productivity, 5th percentile discharge, 95th percentile discharge, day of minimum discharge, day of maximum discharge, and coefficient of variation of discharge. Average data includes maximum watershed proportion of snow covered area, precipitation, temperature, evapotranspiration, green-up day, net primary productivity, 5th percentile discharge, 95th percentile discharge, day of minimum discharge, day of maximum discharge, and coefficient of variation of discharge. Land use, lithology, snow covered area, precipitation, temperature, evapotranspiration, green-up day, and net primary productivity were sourced from public, globally available spatial datasets. Nitrogen, phosphorus, and discharge data were sourced from public and/or published datasets. Watershed characteristics and environmental variables were used in a series of random forest models to assess the drivers of 1) average fluvial silicon concentration regime; 2) annual fluvial silicon concentration regime; and 3) the minimum and maximum silicon concentrations within a given regime.

Riverine silicon (Si) plays a vital role in governing primary production, water quality, and carbon sequestration. The Global Aggregation of Stream Silica (GlASS) database was constructed to assess changes in riverine Si concentrations and fluxes, their relationship to available nutrients, and to evaluate mechanisms driving these patterns. GlASS includes dissolved Si (DSi), dissolved inorganic nitrogen, and dissolved inorganic phosphorus concentrations at daily to quarterly time steps, daily discharge, and watershed characteristics for rivers with drainage areas ranging less than 1 square kilometer to more than 4 million square kilometers and spanning nine climate zones. Chemistry and discharge data range between years 1963 and 2024. Watershed and climate data range between 1948 and 2024. GlASS uses publicly available datasets, ensuring transparency and reproducibility. Original data sources are cited, data quality assurance workflows are public, and input files to a common load model are provided.First posted - October 4, 2024 Revised - July 11, 2025 (version 2.0)

This dataset includes monthly dissolved silicon (DSi) concentration data from 198 rivers across the Northern Hemisphere. Concentration and discharge data were sourced from public and/or published datasets and the Weighted Regressions on Time, Discharge, and Season model (Hirsch et al. 2010) was used to estimate monthly concentrations and flow-normalized concentrations for all sites over their period of record. Sites span eight climate zones, ranged from 18 degrees N to 70 degrees N, and vary in drainage area from < 1 km2 to nearly 3 million km2. These monthly concentration data were then used to cluster sites into average (i.e., average of all years) and annual (i.e., each year individually) seasonal regimes using a time-series clustering approach. The annual regimes were used to quantify how often a site moved among regimes over its period of record (i.e., stability). Site characteristics including climate zone, discharge, and concentration-discharge behavior were explored as potential drivers of cluster membership and stability.