Critical load of sulfur

Calculate the critical load. This step includes the calculation of critical loads of sulfur, nitrogen and the total acidity in a steady-state situation for the receptors of choice or for all receptors in all cells of EMEP or LoLa grid (150 x 150 km 50 x 50 km 25 x 25 km 1 x 1°, 10 x 10, etc.) of a region using a GIS (to produce critical load maps). 

Critical loads of sulfur and nitrogen, as well as their exceedances are derived with a set of simple steady-state mass balance (SSMB) equations. The first word indicates that the description of the biogeochemical processes involved is simplified, which is necessary when considering the large-scale application (the whole of Europe or even large individual countries like Russia, Poland or Ukraine) and the lack of adequate input data. The second word of the SSMB acronym indicates that only steady-state conditions are taken into account, and this leads to considerable simplification. These models include the following equations. 

Consequently, risk assessment process is the obligatory continuation of the process of quantitative calculation and mapping of critical loads of sulfur, nitrogen and acidity at various natural and agricultural ecosystems. This is connected with numerous uncertainties a priori included in the computer algorithm for CL calculations ... 

Figure 1. The 5th percentiles of the maximum critical loads of sulfur, CLmaxS, and of the minimum critical load of acidifying nitrogen, CLminN (Posch et aL, 1999).

Figure 3. Temporal development (1960—2020) of the exceedance of the 5th percentile maximum critical load of sulfur. Whileareas indicate non-exceedance or lack ofdata (e.g., Turkey). Sulfur deposition data were provided by the EMEP/MSC-W (Posch et al.,1999).

Figure 16. Critical loads of sulfur on the ecosystems in the Russian Northern Asia (Bashkin and Kozlov, 1999).

Figure 17. Critical loads of sulfur at terrestrial ecosystems of China (Hao et al., 1998).

Using the above-mentioned constituents, the critical loads of sulfur were calculated for the natural terrestrial ecosystems over Korea. Geographical distribution of CLmaxS values is shown in Figure 19. 

Figure 20. Exceedances of critical loads of sulfur over South Korea (Park and Bashkin, 2001).

Craenen, H., Ranst, E. V., Tack, F. M. G., Verloo, M. G. (2000). Calculation and Mapping of Critical Loads of Sulfur and Nitrogen in Flanders, Belgium. The Science of the Total Environment 254, 55-64. 

Park, S-U., Bashkin, V. N. (2001). Critical loads of sulfur on Korean ecosystems. Water, Air and Soil Pollution, 132(1-2), 19 11... 

Critical loads of sulfur and nitrogen on North Asian ecosystems The models for calculation of critical loads in North Asian ecosystems are shown in Box 3. In the ecosystems of the Asian part of Russia these values of critical loads for N, CL(N), and S, CL(S), compounds are shown to be less than in Europe due to many peculiarities of climate regime (long winter with accumulation of pollutants in snow cover) and depressed biogeochemical cycling of elements (see Chapter 7, Section 1). The minimum values of both CL(N) and CL(S) are < 50 eq/ha/yr. and the maximum ones are > 300 eq/ha/yr. (Figure 24 and Figure 25). 

Critical loads of sulfur and acidity on Chinese ecosystems... 

Taiwan Forest ecosystems. A RAINS-ASIA impact module is used to assess ecosystem sensitivity to acid deposition and to calculate critical load of sulfur to six forest ecosystems in Taiwan (Lin, 1998). Results indicate that forest ecosystems in Taiwan are very sensitive to acid deposition due to their low soil pH (< 5.5). Lowland subtropical forest ecosystems in Taiwan have low or moderate low critical loads for S suggesting that they are vulnerable to acid deposition (Table 5). 

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