Ion Mass Balances and Seasonal Fluxes from Four Acidic Brownwater Streams in Nova Scotia

Abstract

Precipitation and four brownwater streams in southwestern Nova Scotia were sampled for 3–5 yr. Precipitation cation chemistry was dominated by H+ (44% of cation equivalents) and Na+ (38%), while anions were dominated by Cl− (44%), SO42− (41%), and NO3− (15%); mean annual pH was 4.6, and acidity was correlated with concentrations of SO42− (r = 0.90) and NO3− (r = 0.82). Surface water chemistry was dominated by Na+ (51% of cation equivalents), Mg2+ (17%), and Ca2+ (16%), while H+ averaged only 4%; anions were dominated by Cl− (53%), organic anions (23%), and SO42− (21%); H+ was not strongly related to concentrations of other ionic constituents (the most consistent correlation was with sulfate, but this was weak and accounted for <30% of the variation). Hydrogen ion was consumed in all four watersheds by an average value of >75%. Water flow was by far the strongest determinant of annual pattern of flux of chemical constituents from the watersheds. Seasonal variations of concentration were of relatively small magnitude and had much less influence on patterns of flux.