Sea Technology

JUN 2017

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30 st / June 2017 sea-disposed munitions and vice versa. The tech- nological objectives were to develop and demon- strate effective, cost-efficient methodologies for surveying and sampling other historic munitions sea disposal sites. The HUMMA team focused on several ques- tions: Where were munitions disposed; how are they presently distributed; what is their physical condition; are they having a measurable effect on the environment; and can future effects be predict- ed as munitions continue to deteriorate? Spatial and temporal scales were critical to achieve the HUMMA objectives. The project re- quired an approach that was broad enough to find munitions and delineate their disposal distribution over hundreds of square kilometers and, concur- rently, detailed enough to evaluate the centimeter- scale effects of munitions and their components on adjacent sediments, seawater and biota. Time- series investigations using time-lapse photography and repeated sampling around specific munitions allowed the HUMMA team to investigate changes on and near the munitions over periods ranging from days to a couple of years. Results Consolidated results of the HUMMA project (published in 2016 in a special issue of Deep-Sea Research Part II) derive from five sea-going field programs. The first and third field programs, in 2007 and 2011, used a 120-kHz phase-differenc- ing sonar system built and operated by the Univer- sity of Hawaii (UH) to locate munitions. In 2009 and 2012, the UH Pisces submersibles (human-occupied vehicles, or HOVs) gave HUM- MA researchers close enough proximity to image thousands of munitions at the centimeter scale and collect sediment, water and biota samples within 2 m of 39 chemical and conven- tional munitions and control sites. Although munitions con- stituents—materials originating from the munitions, including chemical agent, explosive and nonexplosive materials, such as metals—were detected at trace levels in some locations, all of the levels were well be- low screening levels estab- lished for human risk; indeed, shrimp scavenging nearby and sea stars living directly on top of munitions exhibited no contamination from mustard or its degradation products. Metals in sediment samples were also found to be below screening levels for human risk and consistent with the background environment around Hawaii. The fifth and final field program, conducted in 2014, used the Woods Hole Oceanographic Institution's Jason 2 ROV to assess munitions in the same field area. Use of an ROV reduced the risk of the sea-going field programs by re- moving humans from the environment, allowing samples to be collected from closer proximity to the munitions. It also act locations, distribution, condition and effects on the en- vironment were virtually unknown. HUMMA provided a unique opportunity to locate and assess munitions and their components in a strategic area close to Pearl and Honolulu Harbors. The objectives of HUMMA were both scientific and technical. The primary scientific objective was to bound, characterize and assess a deepwater munitions sea disposal site, documenting the impact of the ocean environment on (From Top to Bottom) The Pisces sub pre- pares to insert a box corer into sediments approximately 1 m from an M47A2 bomb, which was likely to have contained mus- tard agent when it was disposed in the fall of 1944. To the left of the box corer is a shrimp trap that was deployed minutes before by the sub. Shrimp trap being re- covered by Pisces sub as brisingid sea star resides on munitions casing nearby. Pisces V "swimmer" sits on the submersible sail as the sub is towed back to a research vessel for recovery at the end of a day's opera- tions.

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