SULFUR ACIDITY LOADING IN SOUTH KOREAN ECOSYSTEMS

The applicability of critical load (CL) methodology for the determination of natural terrestrial ecosystem sensitivity to sulfur acidity loading in South Korea was investigated. The sulfur critical load values, CL<SUB>max</SUB>S, were calculated for the terrestrial ecosystems of South Korea using the steady-state mass balance approach. The corresponding mapping of CL<SUB>max</SUB>S was carried out on the scale of 11×14 km grid cells. The estimated CL<SUB>max</SUB>S values depend on the low rate of soil chemical base cation weathering (mainly, 200?400 eq ha?¹yr?¹), relatively low base cation depositions (mainly less than 450 eq ha?¹yr?¹) and base cation uptake (predominantly 300?400 eq ha?¹yr?¹), and in significant degree on high values of acid neutralizing capacity. The latter in turn is connected with relatively high values of surface runoff (maximum 9000 m³ ha?¹yr?¹). It has been shown that about 75% of CLmaxS values are in the range of 1000?2000 eq ha?¹ yr?¹ and about 15% are relatively low values (<1000 eq ha?¹yr?¹). About 10% of ecosystems have CL values more than 2000 eq ha?¹yr?¹. The sensitive and very sensitive ecosystems occur in the southeastern part of the country whereas the sustainable ecosystems are wide spread in the northeastern part. In accordance with sulfur critical load and sulfur deposition patterns, in 1994?1997 the CL<SUB>max</SUB>S values were found to be exceeded in about 40% of total number of Korean ecosystems, mainly in the southeastern part of the country. The average yearly values of exceedances varied from 176 to 3100 eq ha?¹yr?¹.