Sedimentation dynamics in a small dimictic lake in northern Estonia

Abstract

During a yearlong observation, settling fluxes of seston in the epilimnion and hypo- limnion of Lake Viitna Linajarv varied from 230 to 1400 mg m -2 d -1 . Most of the seston consisted of particulate organic matter (POM). The POM content in the dry matter of surface sediments sampled from the entire lake floor was on average over 50%. Seasonal changes in the distribution of chlorophyll a in the lake and the content of POM reveal the important role of fresh planktonic particles in the deposition. A strong correlation between POM and particulate inorganic matter in the settling matter during stratification indicates flocculent settling of the mineral particles. Resuspension from the littoral zone results in the focusing of sediment into the deep basin of the lake.