Calculation of Critical Loads for Cd and Pb for Arables and Forest Soils in Bulgaria

P. SHEGUNOVA and I. ATANASSOV
Institute for Sustainable Development, BG-1504 Sofia, Bulgaria

Abstract

SHEGUNOVA, P. and I. ATANASSOV, 2003. Calculation of critical loads for Cd and Pb for arables and forest soils in Bulgaria. Bulg. J. Agric. Sci., 9: 149–156

The article presents a calculation method to quantify the risk of atmospheric inputs of Cd and Pb to arable and forest soils in three separate regions in South Bulgaria. Critical atmospheric depositions for Cd and Pb (critical loads) were calculated for arable or humus layers of five soil profiles, using a simplified steady state mass balance equation, that describes input and output fluxes of heavy metals. Calculated critical loads for Cd vary between 1.02–3.22 mg.m–2yr–1 for arable lands and between 4.9–5.8 mg.m–2yr–1 for forest soils. The critical loads for Pb vary between 8.06–11.36 for arable lands and 17.7–19.84 mg.m–2yr–1 for forest soils. The critical loads values increase from arable to forest soils. Calculated loads for Cd and Pb are depending mainly on land use type and soil critical limits used as a basis for the calculation.

Key words: critical load, forest soils, arable soils, lead, cadmium, Bulgaria