The Academy’s Patrick Center for Environmental Research is committed to working with local communities to help address their environmental issues and concerns. Recently, our scientists joined forces with a nearby organization and university to test the soil in vacant lots across West Philly to create a clearer picture of the potential contaminants found there.
We reached out to Academy Biogeochemistry graduate students in Drexel’s Department of Biodiversity, Earth and Environmental Science Andrew Payne and Sophia Larson, who participated in the project, to learn more.
Sophia Larson/ANS
What does testing the soil really mean?
Testing the soil means measuring concentrations of harmful contaminants, like lead. To do this, we collect surficial soil samples at different empty lots throughout western Philadelphia and take them back to the lab at UPenn where they are examined for heavy metals using a device called an XRF (X-ray fluorescence) gun.
If you’ve ever watched Star Trek, they use this made-up device called a tricorder to do scans when they’re on alien planets, and it tells them what kinds of rock material or gases are present. The XRF gun can be used in a similar way. You hold it up to the soil sample and it emits X-rays that cause the sample to fluoresce. The fluorescence is then measured by the instrument to determine concentrations of various elements.
Why lead?
Lead is the main contaminant we’re looking for because it is the most common one, and it can be quite harmful. Lead is considered a contaminant because of its health effects. These include irreversible developmental problems in children, leading to reduced IQ, learning disabilities and behavior disorders. In adults, high exposure to lead can cause reproductive issues, kidney damage and high blood pressure.
In the environment, lead can decrease biodiversity, impact reproduction in plants and animals and have neurological effects on animals. Unfortunately, lead in the environment has become ‘normal’ through decades of human use in various substances, but that doesn’t mean we can’t do anything about it.
How does lead get into the soil?
Depending on the absence of historical maps or documents, it may be unclear as to where the source of any potential lead contamination is coming from. Common print shops that used to be operational may have used ink with lead, leading to potentially contaminating the area around it. Lead was regularly used in painting until the 1970s and many homes still contain lead paint. It can enter the soil from paint that has peeled off. Lead was also used in gasoline and was released into the air from car exhaust. The lead would then settle on the ground near highways. Lead could’ve gotten in the soil from lead smelters that used to be common in Philly. In fact, Philly had more lead smelters than any other city in the country.
So, what can we learn from this type of analysis?
We can learn whether lead concentrations are at harmful levels in the soil at these vacant lots. If lead levels are too high, the contaminated soil may need to be removed. We try to collect 25 samples spread across each lot to ensure that enough of the area has been tested. However, it’s not practical to collect samples covering every square foot of the vacant lot, so we don’t know the lead concentrations in areas that are not sampled.
Why is this work important?
Although lead contamination is a problem throughout much of Philadelphia, West Philly has some of the highest soil lead levels. In addition, there are a lot of vacant lots in this part of West Philly that community members are hoping to develop into parks or other uses that will benefit the community. It is therefore a crucial pollutant to monitor prior to recreationally using a space — the end goal of the empty lots.
We also get to work with diverse groups of people and that’s fun. The project was started by the Overbrook Environmental Education Center and the UPenn Perelman School of Medicine. Students from Drexel (four undergrads and two graduate students) and UPenn are also doing the sampling and lab analysis.
This work is important due to the direct impact it can have on people’s lives. If these lots are not contaminated, they can be transformed from a blight into a space that benefits everyone, such as parks that have outdoor green spaces or exercise equipment that could help improve wellbeing and reduce obesity rates. And if the lots are found to be contaminated, we can work together to get them remediated, or at the very least fenced off so that the health of the community isn’t affected.
For farmers, surveying the land is one of the main tasks, as some farms directly depend on it. Sometimes they neglect it because they have large areas of land, but with the help of a drone, for example, you can record the condition of the soil even from a distance, and it is not so resource intensive.