A free-fall water sampler based on the Chopstick water sampler bag will be developed. This Porcupine sampler will be capable of taking up to 36 three-liter water samples at depths controlled from the surface or at depths determined by an internal controller. The sample will be optimized for minimum travel time from the surface to the bottom and back so that the current 4-hour, on-station time for samples to 5000 m depth can be substantially reduced. The rapid sampling cycle and the elimination of the need for an electromechanical cable will greatly reduce the cost of sampling. Provision will be made to incorporate other instrumentation such as Conductivity Temperature Density (CTD) or dropsonde current measurement onto the sampler. The Porcupine sampler will also offer advantages for conventional sampling using electrical cable. To maximize the potential utility of the Porcupine sampler, a parallel study will be undertaken to evaluate characteristics of various plastic film materials for the water sampling bags. A variety of packaging materials consisting of laminates of plastic film and/or metal foils have been developed that are promising as sample bag materials. Some of these materials promise the inertness of fluorocarbons without Freon contamination, and others incorporating metal layers should prove useful for sampling helium and other light gases. Sample bags will be constructed from candidate materials and evaluated both for trace formaldehyde contamination and for helium and neon retention.Anticipated Results/Potential Commercial Applications as described by the awardee:This research should result in a discrete water sampler that will permit rapid sampling to full oceanic depths from a wide variety of ships because the use of acoustic command eliminates the need for conducting wire cable. The sampler will also be compatible with existing cabling and instruments. A variety of sampling bag materials will be available for use with the Porcupine sampler. This variety will widen the types of trace material measurements that can be made with the instrument. The Porcupine sampler will be compatible with CTD systems and, with appropriate acoustic tracking, can provide a Pegasus-like profile of water velocity in the free-fall mode. The Porcupine sample should have broad use in the mesoscale experiments planned for the remainder of this century.
