(4) 
G) 
(7) 
(8) 
(9) 
(10) 
Boine, Judith 
  
4 RESUTLS 
41 Absorption properties 
The absorption of yellow substance can be described as an exponential function. As an initial step the slope S is 
estimated to 0,0487 for acid mining lakes and to 0,0224 for neutral mining lakes between 350 nm and 450 nm (GléBer 
et al. 2000). In natural lakes the properties of suspended matter are characterised by a high content of phytoplankton and 
detritus. The content of inorganic components is not considerable with exception of shore areas. But the suspended 
matter of mining lakes is more influenced by mineral precipitation than by phytoplankton. Therefore the specific 
absorption of tripton in mining lakes is much more higher than the specific absorption of natural lakes (Figure 1). By 
means of these absorption spectra the mining lakes could be divided into four groups. Absorption spectra with similar 
shape were combined. The composition of tripton is subject for further research in order to clear the differences 
between the mining lakes. In acid lakes and in inorganic neutral lakes a shoulder exists at 490 nm by the mineral 
precipitation. 
  
1.0 
——-inorganic neutral 
   
     
    
: £ 
mmm md 
3 
   
— Organe acid 
  
0.8 we OF GAME Neutral 
  
inorganic acid 
0.6 
  
* natural lakes (Hoogenboom, Biopti) 
D E on mM qe m e e M 
- fom nn nn fn 1 0 
i i 8 à 
wm ef nf 
t ¥ x * ge 
Me Rh SR e p o a e o a e s e n eg m m n cas s n erm m mme m e nd 
  
04 
  
    
- nf 
  
Su rmm 
  
specific absorption of tripton a*; [mg] 
  
  
  
  
  
  
  
  
  
à i 
---mR--t- 
: t 
  
400 450 500 o50 600 650 700 750 
wavelength [nm] 
Figure 1. Specific absorption spectra of tripton of mining lakes 
The specific absorption of phytoplankton of mining lakes is similar to the corresponding value of natural inland lakes. 
But in the acid mining lakes an additional peak exists at 650 nm. This peak relates to a higher concentration of 
chlorophyll b. The modelling of the reflectance spectra was carried out with the absorption spectra of Hoogenboom, 
because the chlorophyll b peak is negligible at the reflectance spectra. 
4.2 Backscattering of Tripton 
The classification of the mining lakes into four groups was proved to the analysis of the backscattering spectra too 
(Figure 2). The very high backscattering of tripton in inorganic neutral lakes is very surprisingly. But this is caused by 
the mineral precipitation in these lakes. The precipitation is very fine and the grains are absolutely small. Furthermore, 
the increase of the spectra of organic lakes at 700 nm is unexpected also. However Lindell et al. 1999 in turbid waters 
found similar results. Probably this is attribute to the content of phytoplankton, but this is also subject for further 
research. The backscattering properties of inorganic acid lakes and organic neutral lakes are similar to natural lakes 
between 400 nm and 700 nm. In this wavelength region backscattering is independent of wavelength. The 
backscattering properties are explored not much by wavelength between 750 nm and 850 nm. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 201