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How DIY Science Is Solving Ecological Mysteries In New York City

BY Nick Judd | Thursday, August 25 2011

Aerial imagery via Public Laboratory

The folks at Public Laboratory recently showed off the latest frontier in DIY citizen science: infrared aerial imagery.

These images aren't just for show. A mix of volunteers, students and researchers have been using infrared imagery to solve mysteries about the environment around Brooklyn's historically polluted Gowanus Canal, which, as a U.S. Superfund site, is acknowledged as one of the most polluted places in the country. With development in Brooklyn taking off and the city, state and federal governments trying to figure out what to do about the mix of developer interest and history of pollution along this waterway, folks involved in the project say they can use a mix of aerial photos and infrared maps to answer questions for themselves about pollution and underground streams that might spread it around.

To do it, they've been affixing digital cameras to helium balloons and lofting them overhead during canoe trips along the canal. The Public Lab folks have figured out how to use a filter on the cameras to make them capture near-infrared light rather than the light we see.

Then, using Public Laboratory's Cartagen Knitter software, mappers can piece the resulting images together into cohesive maps. That DIY fact-finding is exactly what Public Laboratory is about, in a variety of ways; one post on Public Lab's website describes how to make an air quality sensor from a Roomba, for instance.

The photo that Public Laboratory's Liz Barry put online happens to be part of the plot where Whole Foods is planning to build a new 56,000-square-foot shopping center, but that's not the most interesting part for Eymund Diegel, an environmental planner participating in the grassroots mapping project around the canal.

What's most interesting about this particular plot is that it looks to be the home of one of a network of now-underground streams that once fed into the canal and have become forgotten thanks to decades of industrial activity. He says the DIY maps built as part of the volunteer Gowanus project take points like that one — a consideration that, in the context of the Whole Foods project, might be dismissed as neighborhood folklore — and turn them into credible concerns backed by hard evidence. How, for instance, is the Whole Foods developer going to make sure pollutants don't get into that underground stream, if in fact it is there, and from there into the canal?

"Getting the data out there is just really important because multimillion dollar design decisions are going to be made in the next few months," Eymund Diegel, an environmental planner participating in the grassroots mapping project around the canal, told me today in a phone interview.

Diegel views these aerial photos like CSI's Horatio Caine would view a crime scene. The obvious trigger for him is the tree right next to the circled area. There's a steel bulwark at the water's edge to keep more pollutants from seeping into the canal. The tree shouldn't be getting its nutrition from the Gowanus, so where is it getting all the water it needs to look so large and healthy? And why is there a thick streak of vegetation running from the tree to the edge of the photograph?

The next is the evidence from the infrared image. The circled area is mostly paler than the rest of the Gowanus, with flecks of red. Diegel says that probably means there's less photosynthesis going on in the pale areas, where the algae feasting on pollutants in the canal may find less to eat. The red stuff could be sediment, or it could just be ripples of water hitting the camera the wrong way — that's definitely what's going on in the large area to along the right side of the image.

Curious, he took a canoe out to that very spot. What he found, he says, was a hole in that steel bulwark — possibly from a stream slowly rusting its way through. The hole was hidden behind a weld in the steel, visible in photos he forwarded along to me by email.

"Someone was trying to conceal some kind of outflow, I don't know why," Diegel says. "It was a natural outflow that collects water from Park Slope, and there's a stream running across the Whole Foods site. Because it was a constant water flow, someone may have connected some industrial flow to it and been dumping paint or whatever else."

It's a hypothesis, he says: A conjecture about what people in industrial Gowanus decades ago may have been doing.

"But why else would you conceal an outflow?" he asks.

It's also completely theoretical to assume that what they've found is a flow of fresh water — the Public Lab blog post about the image calls it a "plume," and one commenter, Cesar Harada, assumed it was oil.

"We're still trying to understand the infrared imagery," Diegel told me. "The reason why it's still problematic is that in theory the infrared should be showing up a flow of two other spots" — the Whole Foods site is along one of several places where centuries-old maps of Brooklyn show freshwater streams once ran; researchers have identified four of them elsewhere in present-day Brooklyn — "but it wasn't."

But getting the definite answer isn't the point. The point is that Diegel, and a whole team of other people analyzing maps of the canal, can get to the next question — or know where to paddle over to take some pictures, uncovering new facts.

The Public Lab folks say there are still more applications for infrared imagery; they have a project coming up in a couple of weeks that will use the techniques to study relationships between wetlands and farms. The team has also moved on to new technologies that answer questions left over by previous methods.

"How would you prove that what we see is oil?" Harada, the commenter on the post about the infrared image of the Gowanus, asked. "Is there a way to do that?"

As it happens, the Public Laboratory is working on a new project: A DIY spectrometer, which could be used to identify contaminants, like oil, in water and air samples.

"Working on it," Public Lab co-founder Jeffrey Warren replied. "Spectroscopy!"

This post has been updated.

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