Seasonal fluxes of particulate matter in a small closed lake in northern Estonia

The seasonal fluxes of dry matter, spheroidal fly-ash particles and pollen were studied in a small mesotrophic lake in order to reveal the patterns of their spatial-temporal distribution in regard to seasonal variations. Sediment traps deployed in the lake at different depths and locations were used to collect samples for calculating sediment fluxes in two years. The results show that resuspension of settled particles in the lake with a small dynamic ratio is moderate and depends on seasonal changes in thermal stratification. The rate of particle deposition during the summer stratification period was low. The weather conditions during early spring, such as air temperature and the thickness of snowcover, influence the intensity of resuspension. Air temperature and cloudiness during the summer stratification period determine the rate of bioproduction and thermocline parameters, which also have a major effect on the seston composition and fluxes.