Development of a mobile airlift pump for scientific divers and its application in sedimentological underwater research

Abstract

To make the advantages of airlift pumps accessible for scientifi c divers working on geoscientifi c topics, the authors developed a mobile airlift pump that operates without any surface support. The device is powered by standard scuba tanks and has a quite slim design. Thus, it can be easily transported by scuba divers with lifting bags. The construction is based on the laws of Bernoulli and Boyle-Mariotte: a defi ned amount of gas supplied at the lowest point of a vertical, semi-closed system will expand while ascending and cause a negative pressure at the bottom. The development and practical testing was carried out in various lakes in Germany and in the Mediterranean Sea during fi eldwork in the hydrothermal system of Panarea, Italy. There, chemical erosion led to sediment-fi lled cavities with diameters of several decimetres that are aligned along geological fractures. The removal of sediment is the main requirement to document the unique but covered lithological structures.