Trace Organic Chemicals in Biosolids: Something Old Something New?
Speaker: Christopher Higgins, Colorado School of Mines
Series: CEE Departmental Seminars
Location: Bowen Hall Auditorium
Date/Time: Wednesday, October 20, 2010, 4:30 p.m. - 5:30 p.m.
The presence of trace organic chemicals in municipal biosolids in the U.S. has received considerable attention by the public and scientific community over the last several years. Of particular concern is whether the presence of these chemicals in biosolids results in significant risks to public health and the environment following land application. Unfortunately, the state of knowledge with respect to the environmental fate, transport, and bioaccumulation of many of the trace organic chemicals recently measured in biosolids is lacking. Two classes of trace organic chemicals present in municipal biosolids in the U.S. and receiving considerable attention are the antimicrobial chemicals and perfluorochemicals (PFCs). Through a series of field-based and laboratory studies, the relative persistence and bioaccumulation of two antimicrobial chemicals, triclosan (TCS) and triclocarban (TCC), was evaluated. The resultant data indicated that TCC is both more persistent and bioaccumulative than TCS, but that TCC behavior was consistent with traditional organic chemical fate modeling paradigms. In contrast, PFCs are anionic surfactants that exhibit both hydrophobic and oleophobic behavior. Analysis of field-collected samples confirm that PFCs persist in biosolids-amended soils, and the land-application of biosolids, as opposed to the atmospheric deposition, is the dominant means by which PFCs accumulate in biosolids-amended soils. Soil depth cores data indicate that PFCs are also transported through the soil column, where they may eventually contaminate shallow groundwater. In addition, desorption experiments indicate that while PFCs may desorb from biosolids-amended soils into soil porewater, some PFCs may be tightly bound to the biosolids matrix. Collectively, these data suggest that assessing the risks of trace organic chemicals in biosolids-amended soils may require the use of both traditional paradigms and new modeling approaches if accurate predictions of chemical fate, transport, and bioaccumulation are needed.