MP13 Aquatic Ecotoxicology
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(ESA-1117-839778) Toxicological effects of military Fog Oil obscurant to Daphnia magna in field exposures.

Esarey, J¹, Soucek, D¹, Cropek, D², Smith, T², ¹ Illinois Natural History Survey, Champaign, IL, USA² United States Army Corps of Engineers Research Laboratory, Champaign, IL, USA

ABSTRACT- The U.S. Army must continually maintain military preparedness and concurrently maintain the various natural resources of military training lands as mandated by the Congress and expected by the public. Preparation for adverse battlefield conditions requires training activities using smokes and obscurants (S&O), and many threatened and endangered species (TES) cohabit training areas where S&O are released. Fog Oil (FO) is a middle distillate petroleum that is vaporized to form a screen during battle and in military field training maneuvers. This research focuses on the impacts of FO obscurant to aquatic TES. Field experiments quantifying and characterizing FO obscurant deposited on aquatic surfaces as well as 48-hour toxicity testing with Daphnia magna following FO exposures were conducted in spring and late summer at Aberdeen Proving Ground in Maryland. Exposure vessels were placed at stations ranging from five to 800 meters downwind of the release point, and for three-, 18-, 30-, and 60-minute exposures. Compared to controls (50 meters upwind of release), significant mortality was observed only at the 5-meter station. This was true for all exposure durations. The number of floaters (neonates caught in a surface film) observed at the 50-meter station (50%) was significantly higher than that in controls (no floaters) after an 18-minute deposition of FO. Fog oil deposition at this station was 0.35g/L total oil, which is nearly two orders of magnitude lower than previously documented effects levels in laboratory studies. Substantial but not significant numbers of floaters were observed as far as 100 meters downwind from the release point after 18 minutes of deposition. FO obscurant was not analytically detectable in water samples at this station. These data will serve to calibrate further laboratory studies investigating the chemical/physical effects of vaporized and photolyzed FO obscurant, and elucidating chronic effects and potential for trophic transfer of FO constituents.

Key words: fog oil, daphnia magna