A light bulb moment sparked a research idea for ERDC-EL’s Dr. Guiherme Lotufo when attending a November 2011 conference as part of the Society of Environmental Toxicology and Chemistry North America’s 32nd annual meeting.
That idea led to insight about the potential novel use of the polar organic chemical integrative samplers (POCIS) for monitoring munitions constituents (MC), the name of his current research project.
In 2001, Lotufo joined with Gunther Rosen from the Space and Naval Warfare Systems Command, Systems Center Pacific to investigate the fate and effects of MC in underwater environments. Since that time Lotufo, Rosen and other scientists from ERDC and SSC Pacific participating in this collaboration have published more than 40 papers detailing their research.
“The Environmental Security Technology Certification Program (ESTCP, project 14E-ER1-016), has funded us since 2013 to optimize the use of a commercially available POCIS for the detection of MC in aquatic environments. The POCIS is a high-sorption sampler four inches in diameter, which is used to detect polar contaminants including pesticides, pharmaceuticals and household products,” Lotufo said.
Leading experiments and field studies
In addition to conducting experiments at the EL Ecotoxicology Laboratory, Lotufo also participated in the field demonstration of the POCIS in 2014, adjacent to the U.S. Environmental Protection Agency’s (EPA) Gulf Ecology Division at Santa Rosa Sound, Florida.
“Fragments of composition B (CB) were added to metal canisters with mesh-like sides and suspended from a research dock just above the sea floor. POCIS samplers were placed inside canisters and deployed at varying distances, directions, and depths, from the ‘source’ canister containing CB. A concentric circle sampling design was employed to examine uptake by the POCIS at increasing distances from the source. After 13 days, all samplers were removed and sent for analysis. Concentrations of contaminants TNT and RDX were highest within 0.3 meters from the source, with rapid reduction to non-detectable levels only several meters away,” Lotufo said.
“The laboratory experiments provided calibration and optimization of POCIS for use with MC in preparation for field deployments. Some of the calibration experiments were the first research project conducted in collaboration with Dr. David Smith at the newly opened flume facility. The most recent experiments addressed the effects of biofouling (gradual accumulation of microorganisms, algae, and animals such as barnacles on wetted surfaces) on the uptake rate of MC by POCIS,” Lotufo said.
Lotufo noted that the laboratory and field experiments showed that MC presence, at concentrations of concern in aquatic environments, are expected to be localized, intermittent, and influenced by the level of projectile corrosion and site conditions, such as temperatures and, currents.
Affected military training ranges
"Because many of the Army’s and Navy’s firing ranges are, or were, located near coastal environments, such as the former naval training range in Vieques, Puerto Rico, concerns exist regarding the potential for unexploded ordnance (UXO) to cause blast-related risks to humans or ecological damage to the environment. Discarded military munitions (DMM), which have been purposefully and improperly disposed of in underwater environments, present similar concerns at DOD sites such as the Ordnance Reef in O‘ahu, Hawaii. POCIS simplifies the sampling process by eliminating the time and effort involved to conduct multiple grab sampling events and multiple analyses,” Lotufo said.
He noted the POCIS detect MC in the water at ultra-low levels and preserve the contaminants of concern once they come into contact with the sorbent, making it a superior method compared to directly sampling numerous liters of water.
Advantages to military sites
“Identifying leaking underwater munitions and measuring MC at low concentrations is highly challenging, in part because introduction of the constituents to the water column may be episodic in nature and sporadic water sampling is unlikely to accurately characterize water concentrations over time.
Without the ability to accurately assess the risks posed by UXO and DMM, DOD sites are faced with increasing regulatory scrutiny which may result in costly assessment and cleanup that can jeopardize routine operations,” Lotufo said.
Lotufo’s research suggests the release of MC from underwater munitions into the aquatic environment is associated with low ecological risk under most exposure scenarios in the marine environment, substantiated by the development of a large body of data illustrating that these chemicals typically undergo extensive dilution and degradation processes, especially upon contact with sediment.
“High concentrations of these chemicals would be required to produce toxic effects. Additionally, these chemicals have virtually no potential for trophic transfer from invertebrates to fish and very low likelihood of exposure to humans via the food chain.
This coming January, Lotufo will join his Navy collaborators for the final phase of the project, the implementation of the POCIS at a former naval training range in Vieques, Puerto Rico.
“Placement of POCIS samplers in the area will provide critical information regarding the magnitude and spatial extent of the release of MC into the underwater environment, to accurately assess risk and determine whether removal is warranted,” Lotufo said.