Basic Water chemistry dataset and GAM-DiD smooth factors of the W-2 catchment in the Sleepers River Research Watershed (with ERW application)

This dataset supports the manuscript "Multiple Lines of Evidence Reveal Rapid, Seasonal Watershed Responses to Enhanced Weathering" (Sun et al.) and comprises three components from the W-2 catchment at Sleepers River Research Watershed, Vermont: (1) streamwater discharge and major-ion chemistry (total alkalinity, calcium, magnesium, sodium, and potassium); (2) streamwater lithium isotope ratios (δ⁷Li); and (3) the fitted smooth terms from the GAM-DiD model. Measurements span 11 May 2022 to 18 April 2025. The associated R code for the GAM-DiD model is available at https://github.com/sfcmarie/GAM-DiD. Units: discharge in mm day⁻¹; alkalinity in µeq L⁻¹; Ca, Mg, Na, K in µmol L⁻¹; δ⁷Li in ‰.