Contaminants in Land-Applied Biosolids: Characterization and Modeling of Fate and Transport During Rainfall Events, and Determination of Effects of Triclocarban on a Freshwater Mudsnail
Studies are described in which the fate and transport of contaminants in landapplied biosolids was characterized via direct measurements and then modeled successfully. Additionally, the effects of one such contaminant, triclocarban (TCC), were investigated in a freshwater mudsnail.
Rainfall simulations were conducted on soil plots amended with biosolids. Surface runoff and leachate was collected and analyzed for the endocrine disrupting chemicals (EDCs) bisphenol A, 17α-ethynylestradiol, triclocarban, triclosan, octylphenol, and nonylphenol; sixteen metals; and estrogenic activity via the ERCALUX bioassay. Triclosan, nickel, and copper were detected at levels that might pose risk to aquatic life, though levels of metals in the biosolids were well below regulatory limits. ER-CALUX results were mostly explained by background bisphenol A contamination and octylphenol, though unknown contributors and/or matrix effects were also found.
An existing model, Groundwater Loading Effects of Agricultural Management Systems (GLEAMS), was modified to include addition of a biosolids phase with labile organic carbon (distinct from soil organic carbon), and was used to predict the fate and transport of trace organic contaminants from land-applied biosolids. The model was calibrated using existing data from literature studies, including experiments described in above, and showed good agreement for acetaminophen, ibuprofen, triclosan, triclocarban, and estrone with reasonable input parameters. It was then applied to various theoretical scenarios using chemicals of varied properties to examine the effects of KOC and half-life, application date, and application method (surface spreading vs. incorporation) on long-term chemical losses.
The effects of TCC were studied in the freshwater mudsnail Potamopyrgus antipodarum. After 4 weeks exposure, environmentally relevant TCC concentrations of 1.6 to 10.5 μg/L resulted in statistically significant increases in the number of unshelled embryos, while 0.2, 1.6, and 10.5 μg/L exposures significantly increased numbers of shelled embryos. The lowest observed effect concentration (LOEC) was 0.2 μg/L, the no observed effect concentration (NOEC) was 0.05 μg/L, and the median effective concentration (EC50) for unshelled effects was 2.5 μg/L. Results indicate that TCC may be causing reproductive effects in the environment. Furthermore, environmental risk from a new class of EDCs is both qualitatively and quantitatively similar to risk from existing classes of EDCs.
Giudice, Ben D., "Contaminants in Land-Applied Biosolids: Characterization and Modeling of Fate and Transport During Rainfall Events, and Determination of Effects of Triclocarban on a Freshwater Mudsnail" (2012). Faculty Publications - Biomedical, Mechanical, and Civil Engineering. 106.
Originally published as a dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Civil Engineering in the Office of Graduate Studies of the University of California, Davis.