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2 TEST SITE
The test sites are parts of the deposit of Eocene Lignite (bituminous brown coal) in the Central Germany region (200
km in south of Berlin). The lignite appears over large areas in great quantities in at least two seems, approximately 5 to
15 meters thick. Marine Tertiary sediments and Pleistocene Glacigen sediments cover them. The marine sediments in
particular, but also the lignite itself, are rich in pyrite and marcasite. A highly acid pore water (pH 2.5—4), caused by the
oxidation of the pyrites, leads to reactive properties in the in the initial mineral comp osition. Intensive acid mine
drainage processes are founded, which the hydrochemical properties of the mining lakes influenced strongly.
3 METHODS
At several days a lot of data were sampled at different sampling points like pH value, Secchi depth, DOC, suspended
matter, chlorophyll and others under different seasonal aspects. Furthermore reflectance spectra (R(0-)) were measured
in different depths and extrapolated to the water surface. A detailed description of the field and analytical measurements
are given in Boine et al. 1999.
"The absorption coefficient of yellow substance and tripton were estimated in the laboratory. The methods and results
are described in Gláfer et al. 2000 in detail.
3.1 Foundations of the modelling of reflectance spectra
The modelling of the reflectance spectra R(0-) is determined after the following equation (Gordon et al. 1975)
b
R(0—) = 0,32 — (1)
a+b,
In remote sensing application remote sensing reflectance R(0+) will be used. With the relation
R(0+) 2 0,544 * R(0—) (2)
the R(0-) spectra were transformed in R(0+) spectra (Lindell et al. 1999).
The application of equation (1) changed equation (2) to
b
R(0+) = 0,174 + — G)
a+b,
a total absorption coefficient [m]
b total backscattering coefficient [m ! ]
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 199
