Phosphorus, an element essential to all life, is impacted by calcium carbonate (CaCO3) co-precipitation and dissolution dynamics across aquatic ecosystems. Changes to climate, hydrology, and eutrophication, coupled with differences in terminology related to naming CaCO₃-producing ecosystems (i.e., chalk, carbonate, karst, travertine), point to the urgency and challenges in understanding this portion of the phosphorus cycle. Forms of CaCO₃ vary across inland aquatic ecosystems, from “whiting events” in open waters to massive travertine or tufa formations to cemented layers on basal resources. And, across lakes, streams, and wetlands, periphyton mats and microbialites may form in photic regions. This dataset was used to create a map of CaCO₃-depositing aquatic ecosystems, with colors indicating where phosphorus co-precipitation studies have occurred. Site information available in the supplemental materials; further information on tufa sites in Europe is available through the Natura 2000 network.

The site names were collected from a literature review of studies on calcium carbonate in inland waters and supplemented with known sites based on personal observation. Site locations were derived directly from the published location whenever possible. If not, the latitude and longitude were determined using Google Earth.