2005 Progress Report: Agronomic Optimization for Phytoremediation of Polycyclic Aromatic HydrocarbonsEPA Grant Number: R831072
Title: Agronomic Optimization for Phytoremediation of Polycyclic Aromatic Hydrocarbons
Investigators: Nedunuri, Krishnakumar , Shann, Jodi R. , Vonderheide, Anne , Lowell, Cadance , Okunade, Samuel
Current Investigators: Nedunuri, Krishnakumar , Lowell, Cadance , Okunade, Samuel
Institution: Central State University , University of Cincinnati
Current Institution: Central State University
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 2003 through March 31, 2006 (Extended to June 30, 2006)
Project Period Covered by this Report: October 1, 2005 through March 31, 2006
Project Amount: $336,649
RFA: Superfund Minority Institutions Program: Hazardous Substance Research (2002) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management , Safer Chemicals
The objective of this research project is to determine the optimal combination of agronomic practices, such as addition of compost, synthetic fertilizer, and irrigation that would allow native species to survive, grow, clean up, and restore sites contaminated with polycyclic aromatic hydrocarbons (PAH). Accordingly, a greenhouse study was conducted to investigate agronomic practices—composting; nitrogen, phosphorus, and potassium (NPK) fertilization; and irrigation—on PAH reduction in PAH-contaminated soil planted with native grass species.
The design of individual treatments, initial sludge preparation, factorial design of treatments involving the six Ohio grasses, and three soil amendments were discussed in the 2004 Annual Report. The ability of these native grass species to survive and grow on the PAH-contaminated sludge was studied. Side-Oats Grama and Canada Wild Rye showed best growth performance among the six grass species studied. These grasses performed better when treated with N-Viro soil (pasteurized biosolid from Fairborn wastewater treatment plant 0.5% N, 0.1% P, 0.1% K) or a combination of N-Viro soil and NPK fertilizer, (Scotts brand pre-emergent fertilizer 20% total N, 27% P2O5, and 5% K2O) and under an infrequent irrigation regime. Switch Grass grew tallest under a frequent irrigation regime but had lower chlorophyll content and plant counts when compared to Side-Oats Grama or Canada Wild Rye. Prairie Brome had high chlorophyll content under an infrequent irrigation regime and when treated with N-Viro soil, however, it had low plant count and low grass height.
The original sludge (sludge before treatment) from the site contained a mixture of petroleum hydrocarbons typically found in diesel fuel. Total petroleum hydrocarbons (TPH) essentially consists of all petroleum hydrocarbons, including the PAH. Year 2 of the research therefore involved analysis of TPH from the treatments undergoing phytoremediation in the presence of native Ohio grasses under different combinations of organic soil amendment, NPK fertilizer, and irrigation schedules. Three-inch cores were obtained from each treatment using a soil core sampler. These cores contained layers of soil amendment, sludge, and topsoil. Soxhlet extraction of the sludge carefully separated from each core was performed, and the extracts were analyzed for TPH and PAH content using gas chromatography/mass spectrometry.
Under frequent irrigation, there was a 10-fold reduction in TPH concentrations across all treatments, including no-grass control. Canada Wild Rye, Side-Oats Grama, and Indian Grass reduced TPH concentrations at least 90 percent in the presence of Enviro+NPK. TPH reduction is greater in the presence of soil amendments than without amendments (top soil). Under infrequent irrigation, there was again a 10-fold reduction in TPH concentrations across all treatments, including no-grass control. Canada Wild Rye and Side-Oats Grama with N-viro and N-viro+NPK showed up to 95 percent TPH reduction compared to control. A two-factor analysis of variance with replication was performed on TPH measurements across the six grass species and across the agronomic practices used in this study as treatments. There were no significant differences in mean TPH concentrations both under frequent (every fourth day) and infrequent (every sixth day) regimes across the six grass species used in this study.
The original sludge extract had the following PAH composition in ppm: Naphthalene 0.160, Phenanthrene 28.9, Fluoranthene 2.62, Pyrene 1.18, Benz(a)anthracene 0.820, Chrysene 0.820, Benzo(b)fluoranthene 3.37, Benzo(k)fluoranthene 26.0, Indeno(123cd) pyrene 8.28, and Benzo(ghi)perylene 12.2. The extract from each core obtained after soxhlet extraction was quantitated, and the amount of PAH in each treatment was estimated. Most PAHs except Benzo(g,h,i)perylene have been dissipated completely. Concentration of Benzoperylene was reduced at least 57 percent.
Root characteristics, such as biomass both fresh and dry weight basis (above and below ground), root density, and root length, were determined using a root washer and scanner system. Penetration of roots through the sludge layer was found across all treatments. The final report will discuss in greater detail experiments conducted to compare root growth across all treatments. Treatments carrying Canada Wild Rye and Side-Oats Grama were analyzed for their support of microbial growth using the classical approach of plate counts and also by DNA and sRNA techniques. Our students under the guidance of Drs. J.R. Shann and Anne Vonderheide carried out these studies in the Biology Department at the University of Cincinnati (UC). Treatments supported significant microbial growth and presence of petroleum hydrocarbon degraders. The final report discusses these microbial studies performed at UC labs.
No future activities were reported by the investigators.