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Sometimes science is like detective work. Welcome to Pulse of the Planet's Science Diaries, a glimpse of the world of science from the inside. Why is it that heavy metal toxic waste moves downstream in a river much more quickly than it would be expected to? Geochemist Michael Hochella thinks that the answer has something to do with nanoparticles, bits of matter that are so small they're measured in billionths of a meter. Michael and his graduate student, Kelly House, have prepared water samples from a polluted river and are examining them under a very powerful microscope.

MH: "We're looking at stored images of nanoparticles. And we're obviously looking for toxic metals that are associated with the minerals that make up these very, very, very small particles. Okay, Kelly, let's look at the particle that we think might have some zinc.
KH: Okay, open that one up
MH: Alright. And so what you make of the toxic heavy metal here?
KH: The minor elements that we can see is maybe a little bit of zinc. There's a couple peaks for zinc, not big, but it would be a trace metal so we wouldn't expect a peak here to be very large.
Yeah, but you know as small as these peaks are, that's really exciting because it's definitely like trying to find a needle in a haystack. I mean, isn't it true that most of the particles you've found so far do not have evidence that they're carrying toxic heavy metals, but a few particles like this one seem to have small amounts of a toxic heavy metal. In this case, zinc.

So, they've found traces of zinc in a nanoparticle. These tiny amounts of a toxic heavy metal could either be very harmful, or entirely harmless, to life in and around the river. That all depends upon how the particles are structured, which is the next question that Michael Hochella and his team are trying to find out. Pulse of the Planet's Science Diaries are made possible by the National Science Foundation. I'm Jim Metzner.