Extended Data Fig. 5: Aquatic Hg concentration of sub-watersheds in China in the absence of MWT plants in 2022.

According to China’s Environmental quality standards for surface water110, the Hg concentration limit for Class-I and Class-II waterbodies is 0.05 μg L–1. The Hg concentration limit for Class-III waterbodies is 0.1 μg L–1, which is the Hg concentration limit for aquatic breeding areas. The Hg concentration limit for Class-IV and Class-V waterbodies is 1 μg L–1. Base map from https://www.tianditu.gov.cn/.