title: Toxicity and fate of two munitions constituents in spiked sediment exposures with the marine amphipod Eohaustorius estuarius.
abstract: The lethal toxicity of the explosive compounds 14C-labeled 2,4,6-trinitrotoluene (TNT) and nonradiolabeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) to the estuarine amphipod Eohaustorius estuarius was investigated in 10-d spiked sediment exposures. The 10-d median lethal concentration (LC50) was determined using the sum molar initial concentration of TNT, aminodinitrotoluenes (ADNTs), and diaminonitrotoluenes (DANTs), as determined by high-performance liquid chromatography (HPLC), and collectively referred to as HPLC-TNT*. Despite expectations of higher toxicity in sandy sediment (Yaquina Bay [YB], OR, USA) compared to relatively fine-grained sediment (San Diego Bay [SDB], CA, USA), LC50 values were similar: 159 and 125 micromol/kg, for YB and SDB sediments, respectively. When expressed as the sum of TNT and all its degradation products (14C-TNT*), LC50s were approximately two times the corresponding LC50s determined by HPLC. The HPLC-TNT* fraction likely corresponds to the most bioavailable and toxic transformation products. The concentrations of 14C-TNT* in tissues were substantially higher than those for HPLC-TNT*, suggesting that compounds other than TNT and its major aminated transformation products were prevalent. Critical body residues were similar for exposures to SDB (11.7 micromol/kg) and YB sediments (39.4 micromol/kg), despite marked differences in the nature of compounds available for uptake in the exposure media. The critical body residues for E. estuarius are lower than those reported for other aquatic invertebrates (83-172 micromol/kg). Unlike observations for TNT, RDX was only loosely associated with SDB sediment, with near complete recovery of the parent compound by chemical analysis. Exposure to RDX did not result in significant mortality even at the highest measured sediment concentration of 10,800 micromol/kg dry weight, nor tissue concentrations as high as 96 micromol/kg wet weight. The lack of RDX lethal effects in this study is consistent with results reported for other invertebrate species.
authors.affiliation: Space and Naval Warfare Systems Center, Marine Environmental Quality, 53475 Strothe Road, San Diego, California 92152, USA. gunther.rosen@navy.mil
authors.forename: Gunther
authors.initials: G
authors.lastname: Rosen
authors.forename: Guilherme R
authors.initials: GR
authors.lastname: Lotufo
mesh_terms: D033304:Amphipoda / Q000187:drug effects*; D000818:Animals; D019015:Geologic Sediments / Q000737:chemistry*; D009792:Oceans and Seas; D015996:Survival Rate; D013997:Time Factors; D014050:Toluene / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D014050:Toluene