Multispectral Multibeam Echo Sounder Backscatter as a Tool for Improved Seafloor Characterization

The establishment of multibeam echosounders (MBES), as a mainstream tool in ocean mapping, has facilitated integrative approaches towards nautical charting, benthic habitat mapping, and seafloor geotechnical surveys. The combined acoustic response of the seabed and the subsurface can vary with MBES operating frequency. At worst, this can make for difficulties in merging the results from different mapping systems or mapping campaigns. However, at best, having observations of the same seafloor at different acoustic wavelengths allows for increased discriminatory power in seabed classification and characterization efforts. Here, we present the results from trials of a multispectral multibeam system (R2Sonic 2026 MBES, manufactured by R2Sonic, LLC, Austin, TX, USA) in the Bedford Basin, Nova Scotia. In this system, the frequency can be modified on a ping-by-ping basis, which can provide multi-spectral acoustic measurements with a single pass of the survey platform. The surveys were conducted at three operating frequencies (100, 200, and 400 kHz), and the resulting backscatter mosaics revealed differences in parts of the survey area between the frequencies. Ground validation surveys using a combination of underwater video transects and benthic grab and core sampling confirmed that these differences were due to coarse, dredge spoil material underlying a surface cover of mud. These innovations offer tremendous potential for application in the area of seafloor geological and benthic habitat mapping.

Experimental Research on the Concept of Using an Autonomous Transport Module for Transport From the Seabed

The great interest in the exploitation of sea deposits has in recent years resulted in the creation of many consortia conducting research on various methods of mining and transport to the surface. Exploitation of the shelf areas of crude oil and gas as well as solid minerals is successfully carried out in many places around the world using various methods. More and more often, however, we want to obtain natural resources found at great depths such as polymetallic nodules and massive polymetallic sulphides. This puts much greater demands on scientists and engineers. Unfortunately, solutions developed so far are characterized by high energy consumption. For several years, the authors have been researching new concepts of transport from the seabed. In previous years the authors presented theoretical research results of using a new method involving the use of pyrotechnic materials as a source of energy in transport from the seabed from large depths and experimental ones with the use of potassium nitrate and ammonium nitrate in a controlled pyrotechnic reaction and they compared three conceptions of transport of dredge spoil from the point of view of energy demand. This publication presents the results of the continuation of research, this time on the concept of building an autonomous transport module and its operating principles. The construction of the laboratory stand and the way of conducting experiments are discussed. The results of experimental research are presented, which confirm the possibility of using the discussed concept in transport from the seabed.