Government & Politics

Q&A: Getting down and dirty with soil contamination


Howard Mielke, a researcher for the Tulane/Xavier Center for Bioenvironmental Research Center, has been collecting soil samples in New Orleans since the late 1980s. Much of what we understand about lead contamination in soils, both locally and abroad, was culled from studies conducted by Mielke, particularly during his time at Xavier University before Hurricane Katrina.

Since the levee disasters, Mielke’s samples have been examined for further studies showing new cases of lead and arsenic in the soils from floods and demolitions. He also is part of a new study to be released later this month that shows that treated wood used near playgrounds has deposited high levels of arsenic in the dirt.

With financing from the Greater New Orleans Foundation, Mielke is leading a pilot project that involves cleaning the soil around childcare facilities around the city.

Meanwhile, the city is awaiting state approval for a lead remediation program and for a “bioremediation” project, which Mielke says will have suboptimal effects.

The Lens spoke with Mielke about these efforts to clean New Orleans’ soil:

The Lens: Explain the project you are leading to address soil contamination here:

Howard Mielke: We are doing a remedy that we call ”Cover”, where we place a geo-textile layer and then put clean soil on top of that. The geo-textile layer is a material that is permeable, meaning water can go through it, is bright orange in color and it’s difficult to put a shovel through it. It’s a warning layer that’s laid down and then covered with 6 inches of clean soil. We’ve done this already at a number of childcare centers throughout the city. We have 130 childcare centers, and most of those probably need some work because there are lead and arsenic found in a lot of areas. It’s a good start to make the environment safer for people.

The Lens: What are some of your more current soil sample studies saying about contamination?

Mielke: We took samples both immediately after Katrina and then again later, so we  have three sets of samples (including samples taken 1998 – 2000). We also did another study where we’ve been finding much higher arsenic as related to the treated wood in playground areas. It’s important to know the difference between the general amounts of arsenic in soil and what we’re seeing in really high numbers right next to where kids are playing. A third of the playgrounds that we looked at had CCA-treated lumber with high levels of arsenic found in the soils next to it. Those samples were done the summer of 2008.

The Lens: Arsenic has been found in your studies to exceed levels that are supposed to trigger clean-ups from the state and federal government. Why hasn’t that been happening?

Mielke: Well, I’m a researcher and there’s a big gap between what I do as a researcher and what the Department of Environmental Quality and the Environmental Protection Agency decide to do. The EPA came in to New Orleans and found very high lead levels and decided not to do anything. My samples were found before Katrina and they said that if it is historic then they don’t have to do anything. Meanwhile, the city has become highly affected with lead. Every city has these same problems because of combinations of old houses and heavy car traffic. There’s lead in gasoline so with all those cars we dust the interior of cities with lead. Also of course older buildings with lead-based paint on them contribute to the problem. We are not doing what’s required to improve the environments for children.

The Lens: The city has two projects budgeted for soil remediation, with one of those for bioremediation. Bioremediation aims to have plants, in this case sunflowers, soak up metals from soils. Will they be effective enough?

Mielke: I’m not involved in either one of those. But bioremediation is something I’ve looked at and I”m not convninced it’s going to help. Plants can’t take up lead easily. It’s misleading to say that you can put plants on lead contaminated environments and expect plants to do anything. To be effective you would need 150 years of this planting, and we really need to do something immediately. We don’t have 150 years to wait. It is so attractive to everyone to put up sunflowers and think somehow that would make the world clean, but unfortunately if you look at the before-and-after you’re not getting anything out of it. They pick up cadmium but not lead. I just don’t want people thinking they are going to be safe for children because they put sunflowers on the ground and then find out later that it’s still not safe. We can’t have false hopes, we have to do something real.

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