At Aberdeen Proving Ground Research Articles

Characterization of a Microbial Consortium Capable of Rapid and Simultaneous Dechlorination of 1,1,2,2-Tetrachloroethane and Chlorinated Ethane and Ethene Intermediates

ABSTRACT Mixed cultures capable of dechlorinating chlorinated ethanes and ethenes were enriched from contaminated wetland sediment at Aberdeen Proving Ground (APG) Maryland. The “West Branch Consortium” (WBC-2) was capable of degrading 1,1,2,2-tetrachloroethane (TeCA), trichloroethene (TCE), cis and trans 1,2-dichloroethene (DCE), 1,1,2-trichloroethane (TCA), 1,2-dichloroethane, and vinyl chloride to nonchlorinated end products ethene and ethane. WBC-2 dechlorinated TeCA, TCA, and cisDCE rapidly and simultaneously. A Clostridium sp. phylogenetically closely related to an uncultured member of a TCE-degrading consortium was numerically dominant in the WBC-2 clone library after 11 months of enrichment in culture. Clostridiales, including Acetobacteria, comprised 65% of the bacterial clones in WBC-2, with Bacteroides (14%), and epsilon Proteobacteria (14%) also numerically important. Methanogens identified in the consortium were members of the class Methanomicrobia, which includes acetoclastic methanogens. Dehalococcoides did not become dominant in the culture, although it was present at about 1% in the microbial population. The WBC-2 consortium provides opportunities for the in situ bioremediation of sites contaminated with mixtures of chlorinated ethenes and ethanes.

Osprey—From the Sea to the Pond

ABSTRACT In July and August of 1995, USS Osprey (MHC 51) was successfully transferred from the Chesapeake Bay to the Underwater Explosion (UndEx) Shock Test Facility (UTF) test pond at Aberdeen Proving Ground (APG) in Aberdeen, MD, for shock testing. The transfer was the culmination of a coordinated U.S. Navy, U.S. Army, and industry program to utilize the unique capabilities of the APG‐UTF for shock testing of this new class of glass‐reinforced plastic (GRP) vessel. A significant part of the transfer was the design and construction of a transfer cradle that was used to both support the MHC 51 on a barge towed from Norfolk Naval Shipyard (NNSY) to APG and to interface the ship with the ground rail transfer system and marine railway at the UTE The transfer of the MHC 51 from sea to the pond and back to sea was a complete success. It was conducted safely, without harm to either the ship or any of its crew. It was conducted on schedule and within an established budget. In addition, the project was a good demonstration of both inter‐service and intra‐service cooperation, and the ability of the services to employ commercial marine practices and ABS certification.

Observation and simulation of armature contact performance in the cannon-caliber electromagnetic gun

Major components developed under the Cannon-Caliber Electromagnetic Gun (CCEMG) Program are presently undergoing tests at the U.S. Army Research Laboratorg (ARL) located at Aberdeen Proving Ground (APG), MD. The CCEMG launcher is a series-augmented barrel 2.25 m in length and has a rectangular bore cross section of 17.3 mm/spl times/37.3 mm. The system is designed to operate with a peak current of 835 kA, a launch package mass of 185 g, and an exit velocity of 1,850 m/s. CCEMG is a multishot system demonstrator. The test results we discuss here are for single-shot operation. The muzzle voltage in an augmented launcher contains contributions from the fields due to the augmenting turn. These imposed voltage terms tend to mask the transition of the armature contact, thereby making the transition event less discernable than in a simple railgun. The Army Railgun Modular Simulator (ARMS) computer code has been modified to provide a one-dimensional (1-D), lumped parameter model of the launcher and contact wear at the armature-to-rail interface. The CCEMG launcher data are used to further validate the ARMS code and contact wear model. Additionally, a two-dimensional, transient finite difference (2-D TFD) model is used to assess heating in the armature. In this paper we present photographic and electrical data from two shots in which armature performance is simulated.

Sulfur mustard as a carcinogen: Application of relative potency analysis to the chemical warfare agents H, HD, and HT

A relative potency method for assessing potential human health effects from exposures to relatively untested chemicals is presented and documented. The need for such a method in evaluating the carcinogenic potential of the chemical warfare agent sulfur mustard (agent HD) from a limited data base is specifically addressed. The best-estimate potency factor for sulfur mustard relative to benzo[ a]pyrene is 1.3, with an interquartile range of 0.6 to 2.9. The method is applied to (1) the estimated fence-boundary air concentrations of mustard during operation of a proposed agent incinerator at Aberdeen Proving Ground (APG), Maryland, and (2) the current approved general population exposure level of 1 × 10 −4 mg HD/m 3 and the occupational exposure level of 3 × 10 −3 mg HD/m 3. Maximum estimates of excess lifetime cancer risk for individuals at sites along the APG boundary range between 3 × 10 −8 and 1 × 10 −7. Lifetime cancer risk estimates ⩽ 10 −6 are not now regulated by the U.S. Environmental Protection Agency or the Food and Drug Administration. Maximum estimates of excess lifetime cancer risk assuming daily exposure to the approved standards during the proposed 5 years of incinerator operation are on the order of 10 −5 for the general public and 10 −4 for the worker population. These values are considered upper limit estimates.