Marla Bianca '13
2012 Soar Student
Major/minor: Double Major-Chemistry and Environmental Science
Hometown: Reinholds, Pa.
Project: Determination of heavy metal uptake by plants in the Lehigh Gap Wildlife Refuge remediation areas and analysis of the biochemical, ecological, and management consequences
Project advisor: Dr. Diane Husic
Project details: The Lehigh Gap Wildlife Refuge (LGWR) is a 750-acre reserve on the Kittatinny Ridge (Blue Mountain), along the Lehigh River in northern Lehigh and southern Carbon counties, Pennsylvania. While approximately half the site is currently good wildlife habitat, including ponds, wetlands, bottomland forest, riparian zone, wooded slopes, cliffs, talus slopes, and savanna, the remainder of the site has been impacted by air pollution from former zinc smelters in Palmerton and is one part of the Palmerton Superfund site managed by the U.S. Environmental Protection Agency (EPA). In fact, this is the largest Superfund site east of the Mississippi River.
The soil in the Superfund section of the LGWR is contaminated from the zinc smelting operations that occurred in the area. Zinc levels of 20,000 ppm or higher have been recorded. Lower levels of lead and cadmium are also present. Acid deposition resulting from decades of sulfur-dioxide emissions from the smelters originally killed off much of the vegetative cover on the mountains. Subsequently, severe erosion of topsoil off the mountain and heavy metal contamination of the remaining soil kept most plant species from growing back. The smelting operations ended by 1980, but until relatively recently, the site lacked vegetation.
In 2003, an innovative plan to remediate the portion of the Superfund site at the LGWR began. Warm season native grasses (prairie grasses) were planted with the hopes that they could tolerate the metals based on observations of their ability to grow in soils that are naturally high in heavy metals. As was predicted at the early stages of the revegetation work, establishment of the grasses allowed other plant species to begin growing through natural succession processes. Studies in 2007 and 2008 conducted by Moravian College SOAR students showed that the most prominent successional species (gray and sweet birch and aspen tree species) were taking up significant levels of metals. Such uptake interferes with the remediation plan to immobilize heavy metals in the soil and to minimize the flow of metals through the food chain or into the Lehigh River at the bottom of the mountainside. As a result of this work, discussions are underway with the EPA and other consultants as to the proper management of this problem.
Therefore, for this SOAR Project, there was analysis of metal uptake in plant species that had been tested before, as well as plant species that had not tested at the site. This was done to see whether the uptake of metals continues to occur in the early successional species (the birches and aspens in particular) in addition to the species that had yet to be tested. Also, part of testing species that had not been tested before let us test the host plants, such as milkweed, thistle, and butterfly bush that are required for the endangered Regal Fritillary butterfly. Knowing if these plants are taking up metals or not, is an important part seeing if it is safe to introduce the butterfly larvae at the LGWR site. As well, to get a better idea of how the zinc in the soil effects the plants, the LI-COR Photosynthetic Machine was brought out into the field and used on various plants to see if there was any correlation between the concentration of zinc in the leaves and the photosynthetic rate of the plants.
Why I wanted to participate in SOAR: I would like to go to graduate school for Environmental Chemistry after graduation so I talked with Dr. Husic about a research project that would be able to incorporate both chemistry and environmental science. She told me about her experience with the Lehigh Gap and the previous SOAR studies done there in 2007-2008. She proposed a project for me that was what I was looking for because I would have a chance to be a part of a unique conservation and restoration project at the Lehigh Gap Wildlife Refuge as well as have a chance to do research that combined aspects of both of my majors.
Results: Our preliminary results showed that all the plants, including the one that had previously not been tested, are all taking up metals. The milkweed and butterfly bush have relatively low levels of zinc, but the thistle is a bit higher (this is a relatively good sign for the Regal butterfly). In addition, the preliminary results showed the birches and other early successional species continue to take up metals. The gray birches have a range from in the hundreds to over two thousand parts per million Zinc in their leafy tissues. We sampled some of the same gray and sweet birch trees more than once throughout the summer to see if the concentration of heavy metals, primarily zinc, increased and the results show an increase in zinc as the growing season continues.
Future plans: I plan to continue this research with Dr. Husic in the form of an honors project in the fall.