Searching the seafloor for toxic waste
Toxic waste dumped in seas and oceans can significantly disrupt these delicate ecosystems. In order to protect these valuable resources, it is necessary to locate these sites and assess the environmental threat. It is difficult and expensive to access these sites directly thus remote sensing is often employed. The Energy, Environment and Sustainable Development Programme funded the SITAR project consortium to advance acoustical imaging and processing techniques. The French Naval School, a participant in the SITAR project, enhanced conventional Synthetic Aperture Sonar (SAS) by applying interferometry techniques based on wideband algorithms. Data collected from parallel beams is analysed to provide height data and subsequently construct detailed three-dimensional images of the seafloor. The innovation lies in the use of parametric arrays to derive low and high frequency maps simultaneously. The low and high frequency data provide different types of information, thus valuable insight can be gained that can used to help detect buried waste containers. Following initial calibration, the new technique was tested out on a known site contaminated with toxic waste following World War II. The French scientists, along with their SITAR partners, are currently publishing the results of their work in peer-reviewed journals as well as a comprehensive book about the project.