Science Diary: How Toxins Move – Down the River
Music; Ambience: Clark Fork River, water running, birds chirping
JM: Welcome to Pulse of the Planet’s Science Diaries, a glimpse of the world of science from the inside. Michael Hochella is a geochemist at Virginia Tech. He’s been studying nanoparticles, or nanocrystals, bits of matter so small they’re measured in billionths of meters. Michael thinks that nanoparticles might be responsible for the rapid movement of heavy metal pollution in rivers.
MH: “The heavy metals get associated with the nanoparticles when they’re are growing, or after they grow. So, lets take a nanoparticle or a nanocrystal like an iron sulfide. As these molecules or atoms come together, they start building up these incredibly small nanocrystals. If arsenic is also present in the environment, that element may combine with the iron and sulfur to put very small amounts of the arsenic in the growing iron sulfide nanocrystal. So in that way, the toxic heavy metal is actually a component of the nanocrystal. Another way is arsenic can actually attach to the surface of the nanoparticle. This makes a big difference to living things, if you ingest one of these toxic nanoparticles, as to whether the arsenic is going to be on the surface of the particle, or buried in the particle somewhere.”
JM: And how would being a part of a nanoparticle change the way that a toxic metal moves downstream?
MH: “If the toxic metal is associated with a nanoparticle, that particle is so small that it can remain suspended in the river water or in the ground water, essentially indefinitely. It has the possibility of traveling very long distances.”
JM: Learning more about the structure of nanoparticles is the next step for Michael Hochella. Pulse of the Planet’s Science Diaries are made possible by the National Science Foundation.