10 Jahre Depositionsmessung in deutschen Waeldern - eine Synopse

1995

S. 483-488

43 Lit. Ang.

Unselbständiges Werk

200038953

On the basis of 10-year measurement series of 22 deposition measuring stations under spruce stands in Niedersachsen (Lower Saxony, 5), Nordrhein- Westfalen (North-Rhine/Westphalia, 3), Rheinland-Pfalz (Rhineland Palatinate, 6) and Baden-Wuerttemberg (8) a survey is given of the level and development of depositions of sulphur, nitrogen as well as of related acid input with stand precipitation (through fall) for West Germany during the period from 1983 to 1992. The deposition rates thus ascertained are subsequently compared with the results of 35 other precipitation measuring stations in Hessen (Hesse) and Bayern (Bavaria) as well as of 25 stations in East Germany. It becomes evident that the average values of the 22 stations investigated can be considered representative of the spruce stands in West Germany. A comparison with the input data from the French precipitation measuring network "Cataenat" shows that the forest ecosystems in Germany are on average two to three times higher affected by atmogenous depositions than in France. Finally, the deposition rates of sulphur and nitrogen measured are compared with the national and European emission rates of these substances. The most important findings are: Sulphur: The size of sulphur inputs amounts to 37.1kg of SO4-S/ha and a (through fall) on a 10-year average of all 22 stations investigated. At all 22 stations investigated sulphur loads were declining since the beginning of measurements from about 46kg of SO4-S/ha and a (1983-1986) to the end of the period under review (1989-1992) by about 38% to 28kg of SO4-S/ha and a. This development largely occurs in parallel with a reduction of sulphur emission whose size during the same period in West Germany amounts to about 63%, in Germany as a whole to about 38%, for our direct neighbour states to about 34% and in Europe as a whole to about 29%. Nitrogen: The size of nitrogen input measured in stand precipitation is normally markedly below the actual atmogenous input, according to estimates up to 50%, due to intensive interactions in the crown area (above all absorption processes). On a 10-year average (1983-1992) of all 22 stations nitrogen input of 28.6kg of N/ha x a is measured in stand precipitation, of which half each of nitrate nitrogen and ammonium nitrogen. At the 22 stations investigated nitrogen loads remained practically unchanged from the beginning of measurements (1983-1986) to the end of the period under review (1989-1992). This development slightly diverges from the development of nitrogen oxide emissions: Those declined at European level by 6% and in Germany as a whole by about 10%. The development of ammounium emissions in Europe is, however, unclear. It is estimated that they also declined in Germany as a whole by 23%. Acid: The input of acid also measured with stand precipitation is significantly below actual total input levels due to interactions in the crown area. The size of acid input from hydrogen ions and ammonium ions amounts on the 10-year average (1983-1992) of the 22 stations investigated to 2.07 kmol lAe/ha and a (stand precipitation), half each from hydrogen ions and ammounium ions. The acid pollution at the 22 stations has greatly changed since the beginning of measurements (1983-1986) to the end of the period under review (1989-1992): The share of hydrogen ions of about 1.5 kmol lAe/ha and a at the beginning of the measurement series (1983-1986) declined by about 60% to about 0.6 kmol lAe/ha and a (1989-1992). At the same time the input of acid from ammonium ions increased by about 10% to 1.1 kmol lAe/ha and a. Altogether the acid pollution declined from about 2.5 kmol lAe/ha and a by about 32% to about 1.7 kmol lAe/ha x a. On average meanwhile acid input accounts for about 65% from ammonium ions at these 22 stations. Altogether the deposition measurements show that the input of too many pollutants from national sources, but also from transboundary fluxes of pollutants continues. The critic...