Visualizing Mercury on Surface of Freshwater Particulates
Suspended particulates are primarily responsible for the transport of mercury and toxic methylmercury in freshwater systems; however, little is known about how mercury interacts with particulates. Mercury interactions with phytoplankton and colloidal minerals, two common types of particulates known to be involved in binding and transporting mercury, were studied by a team of scientists from Oak Ridge National Laboratory and Argonne National Laboratory using X-ray fluorescence (XRF) spectroscopy. Using samples from a mercury-contaminated freshwater system, the team found that mercury is mostly found on the outer surface of phytoplankton cells (diatoms) and that it is heterogeneously distributed on mineral particles rich in iron oxides and natural organic matter (NOM). The findings confirm that suspended particles, especially diatoms and NOM-coated oxide minerals, are important sinks for mercury in freshwater systems.
Gu, B., B. Mishra, C. Miller, W. Wang, B. Lai, S. C. Brooks, K. M. Kemner, and L. Liang. 2014. “X-Ray Fluorescence Mapping of Mercury on Suspended Mineral Particles and Diatoms in a Contaminated Freshwater System,” Biogeosciences Discussion 11, 7521-40. DOI:10.5194/bgd-11-7521-2014.