Ultra-violet Radiation in the Sea

Abstract

DURING the Swedish Deep-Sea Expedition with the Albatross, measurements of sub-surface radiation were carried out in different areas, chiefly by means of photo-electric methods. Special attention was given to the study of the biologically important short-wave part of the spectrum. The range beyond 315 mµ with anti-rachitic effects was determined by means of a special technique. Two liquid filters, namely, 18 mm. saturated nickel sulphate solution and 14 mm. picric acid solution (45 mgm. per litre), are used, together with a 6-mm. UG5 glass from Schott und Genossen. These filters are combined with a selenium rectifier cell adapted for the ultra-violet, the liquids being enclosed between three concentric hemispherical quartz shells around the cell covered by the UG5 glass. The centre of gravity for the measured radiation is estimated at 310 mµ. The photometer is connected to an Ising galvanometer with a sensitivity of 4 × 10⁻¹⁰ amp. per scale unit.