Why care about sulfate?

Mesocosm tanks with wild rice

May 2023: A panel discussion titled “Why Should Minnesotans Care About Sulfate?” brought together four speakers with scientific, legal, and tribal affiliations on April 3, hosted by the nonprofit Water Legacy. Watch the video in full here (110 minutes). 

Some highlights:

At 26:40, Nancy Schuldt shows that “the science supports maintaining the 10 parts per million sulfate standard” for wild rice waters. In a controlled mesocosm experiment, tanks growing wild rice were loaded with sulfate and sulfide at varying concentrations over multiple growing seasons, mimicking actual conditions. The effects on germination, shoots, and roots were dramatic, as seen in the image here (the roots on the right had high exposure). At 35:50, she summarizes how “sulfate is a bad actor on a number of levels,” upsetting water ecosystems that support wild rice, increasing mercury methylation, contributing to aquatic toxicity, and speeding eutrophication by the release of nitrogen and phosphorous. Schuldt is Water Projects Coordinator for the Fond du Lac Band of Lake Superior Chippewa.

At 42:40, Cara Santelli diagrams the sulfate-to-sulfide cycle in iron-rich ecosystems— such as northern Minnesota— and its impacts on wild rice. Santelli is a geomicrobiologist with the University of Minnesota’s Department of Earth and Environmental Sciences.

At 58:00, Jennifer Pearson, MD, distinguishes between copper nickel mining and other types, focusing on the sulfate-related health effects of mercury methylation. Dr. Pearson is a professor at the University of Minnesota Duluth’s Department of Family Medicine and Biobehavioral Health.

Fond du Lac elder Ricky DeFoe offered prayers and Anishinaabe wisdom to the gathering. Paula Maccabee of Water Legacy introduced the session and provided a wrap-up.