Submitted to: Bioresource Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/14/2007
Publication Date: 1/1/2008
Citation: Smith, K.E., Schwab, A.P., Rock, S., Banks, M.K. 2008. Greenhouse and Field Assessment of Phytoremediation for Petroleum Contaminants in a Riparian Zone . Bioresource Technology. 99:1961-1971. Interpretive Summary: Greenhouse and field studies were conducted to evaluate the ability of plants to clean-up highly contaminated sediments collected from Indiana Harbor. The greenhouse study showed several plant species were able to enhance the loss of total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs) from the contaminated sediments. The plant treatments that showed the most promise in the greenhouse study were the sedge, switchgrass, arrowhead and eastergamagrass. In the field study soils in the presence of arrowhead and sedge had microbial communities capable of degrading PAHs, however no significant differences in contaminant concentrations were observed in the 1 year field study. However, we did find that soil concentrations of TPH near the canal were higher than the soils further from the canal indicating the canal served as a constant source of contamination throughout the study, making it impossible to observe differences in contaminant concentration. In summary, phytoremediation of Indiana Harbor sediments holds great promise, however the major disadvantage is the time required for remediation to take place and in the case of the field sediments, the constant source of contamination makes it difficult to observe the remediation that is taking place.
Technical Abstract: Greenhouse and field studies were conducted to evaluate the feasibility of phytoremediation for clean-up of highly contaminated sediments from Indiana Harbor. In the greenhouse study, plant species evaluated were willow (Salix exigua), poplar (Populus spp.), eastern gamagrass (Tripsacum dactyloides), arrowhead (Sagitaria latifolia), switchgrass (Panicum virgatum), and sedge (Carex stricta). Sediments with sedge, switchgrass, and gamagrass had significantly less residual total petroleum hydrocarbons (TPH) after one year of growth than sediments containing willow, poplar, or no plants. Although not all polycyclic aromatic hydrocarbons (PAH) had concentration differences due to the presence of plants, residual pyrene concentrations in the unvegetated pots were significantly higher than pots containing sedge, switchgrass, arrowhead, and gamagrass. As evaluated by TPH dissipation in the upper section of the pots, the sedge, switchgrass, and gamagrass treatments had higher TPH degradation than the unvegetated, willow and poplar treatments. These trends were similar for soil at the bottom of the pots, with the exception that in the switchgrass treatment, degradation was not significantly different than in the unvegetated soil. Two target contaminants, pyrene and benzo[b]fluoranthene, showed differences in degradation between planted and unvegetated treatments. In the field study, phytoremediation plant species were eastern gamagrass (Tripsacum dactyloides), switchgrass (Panicum virgatum), and sedge (Carex stricta). In addition, rhizosphere characteristics of arrowhead (Sagitaria latifolia) and sedge were assessed. Arrowhead- and sedge-impacted soils were found to contain significantly more PAH-degrading bacteria than unvegetated soils. However, over the 12-month field study, no significant differences in contamination were found between the planted and unplanted soils for TPH and PAH concentrations. TPH concentrations near the canal were greater than concentrations further from the canal, indicating that the canal may have served as a continuous source of contamination during the study.