Discipline: Ecology Environmental and Earth Sciences
Carl L. M. Smith - Southern University at New Orleans
Co-Author(s): Murty S. Kambhampati, Southern University at New Orleans, LA
Previous studies, immediately after Hurricane Katrina, reported that the lead (Pb) content in the Lower Ninth Ward (LNW) of eastern New Orleans, Louisiana (29.95 00o N, 90.06 67o W) at various locations was higher than the maximum acceptable limits in residential or play areas (400 ppm) per the Environmental Protection Agency (EPA). The goal of the project was to determine whether or not the Pb concentration in the LNW soil has decreased since 2005. We hypothesized that the Pb concentration would increase as the distance away from the levee breach increased due to the intensity of flooding. Soil samples were collected randomly from twelve different public locations in the LNW and were analyzed for pH, percolation rate, soil texture, and Pb content. In addition, we conducted phytoremediation studies in Biotronette Environmental Chambers using soybean (Glycine spp.) to remediate Pb in soils. The experimental design consists of 12 treatments and a control, each one with three replicates. Soil and plant samples were analyzed for Pb content using the Inductively Coupled Plasma spectrometer (ICP). Lead concentration in soil samples ranged from 16 to 1698 ppm in N and S locations of the LNW. Three out of the four locations hypothesized to have a relatively high Pb concentration were, in fact, high. Two of the four locations exceeded the residential acceptable limits for Pb with concentrations of 1200 ppm. These results support our rationale that, if the canal is contaminated, as the flood waters reached the watershed, the contaminants carried by the flood waters began to settle. Understanding watershed ecology, the Industrial Canal could have high concentrations of toxic metals and has the potential to do harm to the surrounding environment. We did not find any correlation between the Pb content in soils and the growth rate of soybean plants. ICP results indicated zero content of Pb in stem and a maximum of 76 ppm of Pb in roots of soybean, which could be the reason for the lack of toxic effects of Pb on soybean plants. Additionally, the pH of 5.0, the silty loam texture and the relatively high percolation rate of 0.92 cm/s showed no negative effect on the growth and development. Future research will focus on phytoremediation of the Lower Ninth Ward Pb contaminated soils amended with 10 and 20 mM EDTA using soybean plants under greenhouse conditions to assess the mobility rates of Pb from the roots to shoots.
References: Njoku, K.L., Akinola, M.O. & Oboh, B.O. (2009). Phytoremediation of Crude Oil Contaminated Soil: The Effect of Growth of Glycine max on the Physio-Chemistry and Crude Oil Contents of Soil. Nature and Science, 7(12): 22-30.
Rabito, F., Iqbal, S., Perry, S., Arroyave, W., & Rice, J. (2011). Environmental Lead after Hurricane Katrina: Implications for Future Populations. Environ Health Perspectives, 120 (2): 180-184.
Funder Acknowledgement(s): This project was sponsored by the NSF HBCU-UP grant (HRD-0928797)
Faculty Advisor: Murty S. Kambhampati,