15 Monitoring of Small Catchments in …
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summer, the oxygen content would often drop to 1 mg O 2
. dm
−3 at Lipowiec, whereas
at Koniczynka it remained at a good level. The BOD5 indicated that organic content
was higher at the Lipowiec site than at Koniczynka (Fig. 15.12). That was due to a
substantial content of organic matter in Lake Mlewieckie, using the oxygen dissolved
0
2
4
6
8
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016
mg O2/dm3
Lipowiec
Koniczynka
O 2
0
25
50
75
100
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016
mS/m
Lipowiec
Koniczynka
mS
0
5
10
15
20
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016
mg N-NO3/dm3
Lipowiec
Koniczynka
N-NO3
Fig. 15.12 Mean annual concentrations of O 2, electrolytic conductivity (mS) and nitrate nitrogen
(N-NO 3 ) in the water of the Struga Toru´ nska in 1994–2017