Effects of Soil/Sediment Organic Matter on the Desorption, Bioavailability, Sequestration, and Transformation of PhenanthreneEPA Grant Number: U915550
Title: Effects of Soil/Sediment Organic Matter on the Desorption, Bioavailability, Sequestration, and Transformation of Phenanthrene
Investigators: Soderstrom-Schwarz, Sara B.
Institution: University of Michigan
EPA Project Officer: Carleton, James N
Project Period: September 1, 1999 through July 1, 2001
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1999) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Engineering and Environmental Chemistry , Fellowship - Civil/Environmental Engineering
The objective of this research project is to determine the effects of soil/sediment organic matter on the desorption, bioavailability, sequestration, and transformation of phenanthrene.
Three geosorbents were characterized using 13C-NMR to determine the relative degree of hard and soft carbon. Michigan peat is a relatively young soil from which phenanthrene readily desorbs; Chelsea soil is a high-organic, muck-type top soil with an intermediate hysteresis index; and Lachine shale is a geologically old soil with a high hysteresis index. The sorption isotherms were fit to the Freundlich equation. Soils were aged under anoxic conditions for 2 or 4 months, and the mass of nonradiolabeled phenanthrene was varied to achieve a constant equilibrium aqueous concentration. Radiolabeled phenanthrene in methanol was added to each bottle as a tracer. The bioflasks consisted of a 250-mL flask with a center well for sodium hydroxide (NaOH) and a side arm. A concentrated mineral-nutrient solution and a cell solution of Pseudomonas CRE7, a phenanthrene degrader, were added to the flasks. The NaOH was removed from the center well at sampling to measure the extent of mineralization. Oxygen was added through the side arm to maintain aerobic conditions. Measurements of the desorption rate were conducted using an abiotic infinite sink desorption method with TenaxTA polymer. After mineralization, both combustion and methanol extraction were used to recover 14C-organics from the geosorbents.