LAUSR

Total alkalinity is a pivotal water quality parameter dictating the response of natural waters to acid–base system perturbations such as ocean acidification and acid mine drainage. Its value as a biogeochemical and ecological variable is enhanced not just by high measurement quality, but also by measurement accessibility. This research demonstrates an instrument that advances the accessibility of high‐precision, high‐accuracy total alkalinity measurement using open‐source, and low‐cost instrumentation. Repeated testing of water samples from Lake Superior demonstrated a measurement precision (standard deviation or SD) of 3.0 μmol kg−1. Analysis of standards and reference materials demonstrated an uncertainty of 5.3 μmol kg−1 as well as robustness to freshwater and saltwater matrices. This instrument adds to the wealth of inorganic carbon measurement technologies in marine and lacustrine settings and stands to enhance the ability of both communities to generate accurate and accessible measurements of total alkalinity.