We collected water samples from the river surface using a pre-rinsed HDPE 1 L bottle. During the open water period (June to October), water was sampled by hand either by wading into the river from the shore or from a dock, or, during the ice-covered period (roughly November to May), through a hole drilled through the river ice (20 m from shoreline). During the ice breakup period, a pole with a mounted sample bottle was used. Samples labelled with "transect" were sampled from a boat. Water samples for cations and anions were stored frozen after sampling. After transport samples were analyzed at the Alfred Wegener Institute Helmholtz Center for Polar and Marine Research (AWI) in Potsdam, Germany. The samples were thawed and filtered using a syringe-mounted 0.45 μm CA filter. Samples for cations were then acidified with HNO3 (65%) suprapur. The samples for cation and anion concentrations were kept cool and dark until measurement. Cation concentrations were measured with inductively coupled plasma optical emission spectroscopy (ICP-OES) using a Perkin-Elmer Optima 8300DV. Anion concentrations were measured using ion chromatography (Thermo-Fischer ICS 2100).