|Stream acidification in South Germany: chemical and biological assessment methods and trends|
Braukmann, U. (2001). Stream acidification in South Germany: chemical and biological assessment methods and trends. Aquat. Ecol. 35(2): 207-232
In: Aquatic Ecology. Springer: Dordrecht; London; Boston. ISSN 1386-2588, more
Chemical measurements are designed to classify acid sensitive streams in Baden-Württemberg (South West Germany) as a basis on which a biological indication method for stream acidity is worked out. Sampling of macrozoobenthos is carried out as a basis for the biological classification of the degree of acidity in acid sensitive silicate streams. Interlinking of the chemical and biological data is made with, among others, statistical methods aiming to describe the pH values and other parameters relevant to acidification which effect the presence of the organisms. The sensitivity levels of the benthic macroinvertebrates are related to the pH values and the corresponding indicator values for the bioindication are assigned to the current acidification level of the calcium-poor streams. Relevant data, information, and procedures from literature were hereby taken into account. Computer-aided assessment of the acidity status of the slightly-buffered streams based on the macrobenthic cenosis following the principle of maximum biological sensitivity of the individual taxa has been carried out. This has been done by successive examination of the values of all observed indicator species, beginning with the most acid sensitive ones. Cartographic presentation of the biological results - obtained between 1992 and 1998 - reveals a slight improvement of the degree of acidity in streams of the Black Forest. This can also be observed in the chemical data. Most sampling sites show an increasing trend in pH-values as well as in buffer capacity. On the other hand most of the streams in poorly buffered areas show a declining trend in their aluminium concentrations and their content of sulphate-ions, which is a consequence of the decreasing sulphur-dioxide concentrations in the air during the last 15 years.