Toxicity Evaluation of Contaminated Groundwater at Aberdeen Proving Ground-Edgewood Area West Branch of Canal Creek Phase 1: Groundwater Evaluation.

Contaminated groundwater, which contained multiple heavy metals and chlorinated aliphatic hydrocarbons, from the Canal Creek aquifer well CC-27B of the U.S. Army Aberdeen Proving Ground-Edgewood Area, Aberdeen, Maryland, was evaluated for toxicity to aquatic organisms. Toxicity was detected at various groundwater concentrations by 6 of 8 biomonitoring systems. The lowest concentration of groundwater that caused no observable adverse effect NOEC at pH 4 was 10 ground water by volume in the following assay 4-d green alga Selenastrum capricornutum growth test 7-d cladocaran Ceriodapnia dubia survival and reproduction test and 96-h frog Xenopus laevis embryo teratogenesis assay - Xenopus FETAX. A NOEC of 18 groundwater volume occurred in 7-d fathead minnow Pimephales promelas survival and growth tests. Buffered groundwater pH 7 was less toxic andor not toxic in 7-d fathead minnow tests and in FETAX assays. The 10 groundwater by volume NOECs for the green alga and cladoceran at pH 4 did not change when the organisms were exposed to buffered groundwater at pH 7. The Ames assay for mutagenicity was negative in all cases. Sporadic incidences of lesions were found in Japanese medakaOryzias latipes at concentrations up to 25 groundwater by volume after 9 months of exposure.