Author(s)

A. Tõnisson

Abstract

A. Tõnisson Tartu University, Estonia Abstract During four seasons, in a pine-forested sloping watershed, subsoil water from calcareous soil and sandy soil was collected on 20 occasions. In total 8 lysimeters were used. No clear relationship has been found between total organic carbon (TOC) concentrations, precipitation nor runoff. Percolation of subsoil water into lakes is highly seasonal, occurring primarily in spring and autumn. However, the total contribution of subsoil water into lakes is very limited. The annual estimated flux of TOC past the depth 15 cm below the forest floor under conifers was up to 650 kg/ha. The total emission of TOC from the transitional humus-rich test site was higher by up to 10 times as compared with the sandy site. Hence, particular soils represent large stores of C, which, due to the local water table is not completely available for the adjacent lake. In the case of seepage lakes the flux of carbon does not reach into the lake directly. However, water exchange w

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