Chloride and sulfate concentrations in 1918 Marsh, Madison, WI, 2012-2024

Beginning in 2012, chloride and sulfate concentrations were collected at a suite of sampling locations in and around 1918 Marsh, a small wetland on the University of Wisconsin–Madison campus from 2012-2024. Water temperature, water depth, and ice thickness are provided for each sampling event where applicable. Since fall 2014 water was collected via syringes, and filtered through a 25 mm 0.45µm GMF filter into plastic scintillation vials in the field. All samples were analyzed on an ion chromatograph (Dionex ICS 2100) using an electro-chemical suppressor. Prior to September 2014 samples were taken by dipping the opening of a plastic sample bottle below the surface and the sample was filtered in the Laboratory prior to chemical measurements. Samples were largely from the fall/winter season and taken at ca. 3-week intervals. In these early samples dissolved oxygen was also measured with a DO meter in the field. The University of Wisconsin–Madison deposits plowed snow each winter onto a gravel lot located adjacent to the snowpile. Photos of the snowpile from 2013 to 2024 are also provided, with a vertical pole for scale.