Some quantitative data on light penetration in sediments

Abstract

1. Light penetration in sediments is a function of sediment granulometry; it decreases with the decrease in grain size. 2. Light quantities entering the sediments are a function of substrate depth: At 1 mm depth, light penetration ranges between 80 (at medium quartzy sands from Hel) and 2 (at very fine sands from the Black Sea) percent of the light quantities found at the substrate surface; at 2 mm depth light penetration varies between 52 percent and total darkness (when muds replace sand); at 3 mm depth it varies between 0 and 23 per cent; at 4 mm depth, in most samples the aphotic zone was reached; however, in some sediments (quartzy medium or coarse-medium sands) values up to 9 per cent may occur; at 5 mm depth out of 46 analysed samples only 5 contained up to 5 per cent light; at 6 mm depth the lowest readings of down to 3 per cent were obtained. 3. On the basis of these data, the photic zone in sandy sediments is very thin. © 1967 Biologischen Anstalt Helgoland.