Sulfur acidity loading in South Korean ecosystems

The applicability of critical load (CL) methodology for the determination o f natural terrestrial ecosystem sensitivity to sulfur acidity loading in So uth Korea was investigated. The sulfur critical load values, CLmaxS, were c alculated for the terrestrial ecosystems of South Korea using the steady-st ate mass balance approach. The corresponding mapping of CLmaxS was carried out on the scale of 11 x 14 km grid cells. The estimated CLmaxS values depe nd on the low rate of soil chemical base cation weathering (mainly, 200-400 eq ha(-1) yr(-1)), relatively low base cation depositions (mainly less tha n 450 eq ha(-1) yr(-1)) and base cation uptake (predominantly 300-400 eq ha (-1) yr(-1)), and in significant degree on high values of acid neutralizing capacity. The latter in turn is connected with relatively high values of s urface runoff (maximum 9000 m(3) ha(-1) yr(-1)). It has been shown that abo ut 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(-1) yr(-1)). About 10% of ecosystems have CL values more than 2000 eq ha(-1) yr(-1). The sensitive a nd 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, i n 1994-1997 the CLmaxS values were found to be exceeded in about 40% of tot al number of Korean ecosystems, mainly in the southeastern part of the coun try. The average yearly values of exceedances varied from 176 to 3100 eq ha (-1) yr(-1).