Airdate: Jul 23, 2007
Scientist: Michael Hochella
Science Diary: How Toxins Move - Comparison
The pristine waters of Montana's Rock Creek provide a control sample for researchers studying the state's more polluted waterways.
Ambience: walking through river
How do scientists gauge how much pollution is in a contaminated river? By comparing it to a relatively clean one. Welcome to Pulse of the Planet's Science Diaries, a glimpse of the world of science from the inside. We're with Geochemist Michael Hochella and his colleague, Johnnie Moore, on the banks of Rock Creek in Montana. They're here collecting water samples comparing the levels of heavy metal found naturally in this pristine water to the levels found in the polluted waters of the Clark Fork River. Johnnie Moore.
JM: "The water in this river is very pure and it's one of the world's finest trout fishing rivers. And so here in Montana we commonly use this river as a background stream. It's a stream that we know hasn't been affected much by humans, it's fairly pristine, and you can just see looking at it how different it is from the Clark Fork River. There's no algae growing on it, there's not a bunch of slime. It's a much nicer river."
Geochemist Michael Hochella
MC:"And so scientists like background measurements - what's there before people affected it, or whatever else affected it, what's the background. Let's walk into this, this stream and we'll collect some background water-- man this is even colder.
JM: Yeah, most of its water from snowmelt upstream a few miles and from the tributaries that flow into it.
MH: And I'm getting my shorts wet so let's get those samples Johnnie and get out of here. So, Johnnie's putting the bottles down into the water, he's going to collect oh, probably about six or eight fluid ounces. He's dipping the bottle all the way up and down the water column. We don't expect to find any metal contamination in this water besides what nature can add naturally and so we won't call that contamination, we'll just call it the natural metal load."
The next step is to take these samples into the lab. We'll hear about that in future programs. Pulse of the Planet's Science Diaries are made possible by the National Science Foundation. I'm Jim Metzner.