Effects of macrophytes on the fate of mercury in aquatic systems.

Vegetated and shallow areas such as wetlands and salt marshes, as well as freshwater lakes and rivers, have been identified as hotspots for Hg methylation. The presence of aquatic macrophytes, the predominant primary producers in shallow waters, plays an important but still poorly understood role in the fate of Hg in these environments. The present review focuses on the influences of macrophytes on Hg speciation and distribution in sediments, the rhizosphere, and the water column; on Hg transformation; and on Hg release to the environment, including transfer to the trophic web. Future research will require an improved understanding of the mechanisms and the factors controlling these aspects as well as a broader general view. Thus, the main gaps in knowledge are also discussed.