PM08 Muddy waters: Criteria and TMDL Development
Exhibit Hall
8:00 AM - Monday, 10 November 2003
(PM143) Whole Sediment TIEs: A TMDL Case Study.
Horne, J1, Dorn, P2, Brzuzy, L3, Palachek, R4, 1 PBS&J Environmental Toxicology Laboratory, Houston, Texas, USA2 Shell Global Solutions, Houston, Texas, USA3 Shell Chemical Company, LP, Deer Park, Texas, USA4 Parsons, Austin, Texas, USA
ABSTRACT- Patrick Bayou, a shallow, tidal tributary of the Houston Ship Channel located in Harris County, Texas, receives treated industrial and municipal wastewater and stormwater discharges, as well as non-point source stormwater runoff from nearby suburban areas. Patrick Bayou was included on the State of Texas 303(d) list of impaired waters due to chronic sediment toxicity. Chemical analysis of Patrick Bayou sediments identified many contaminants; however, no constituent was uniquely correlated with the observed sediment toxicity. Whole sediment bioassays conducted with Leptocheirus plumulosus and Neanthes arenaceodentata showed that all of the sediments were toxic to one or the other organism, at least once during the study period. In contrast, pore water toxicity was not observed in any of the samples that exhibited whole sediment toxicity. The lack of pore water toxicity suggested that the causative toxicants were tightly bound to the sediment. Since pore water did not exhibit toxicity, whole sediment toxicity identification evaluations (TIE) were conducted. Although whole sediment TIE is an emerging science and standardized protocols have not been established, a variety of experimental methods -- including use of synthetic resins, ion-exchange media, and activated charcoal -- were identified and incorporated into the Patrick Bayou sediment TIEs. Isolation of toxic fractions and identification of individual constituents was not possible; however, organic compounds were identified as the potential toxicant(s). Results of the sediment TIEs will be presented and the capabilities of the current methods to resolve sediment toxicity in samples from complex, industrialized settings will be discussed.
Key words: sediment toxicity, total maximum daily load (TMDL), toxicity identification (TIE), methods development/evaluation