Poland - IOW

Results 38
Table 3.8: Seepage rates of the 6 benthic chambers (BC) from October 2010.
L m - ² d -1
BC 1 79
BC 2 76
BC 3 28
BC 4 25
BC 5 113
BC 6 13
Figure 3.12: Changes in ammonium δ 15 N values in the benthic chambers (BC) during the
incubation. BC 1 (●), BC 2 (■), BC 3 (▲), BC 4 (○), BC 5 (□) and BC 6 (Δ). For respective
seepage rates see table 3.8. Start of incubation t 0 : 6 th of October at 15.45. End of incubation t 2 :
7 th of October at 16.30.
δ 15 N-NH + 4 values during the benthic chamber incubations were measured as well (Figure
3.12). δ 15 N-NH + 4 values in the chambers 1 to 3 were between 0.8 ‰ and 1.5 ‰. Those three
chambers also showed the highest ammonium flux rates (table 3.8, figure 3.11B). δ 15 +
N-NH 4
values were further decreasing during the dark incubation t 0 to t 1 (from 15.45 till 08.05) to
about 0.2 ‰. During the subsequent light incubation t 1 to t 2 (from 08.05 till 16.30) δ 15 +
N-NH 4
values were slightly increasing again in chamber 1 and 3. In chamber 2 the δ 15 N-NH + 4 values
remained the same. This chamber had by far the highest ammonium flux rate (Figure 3.11B).
In chamber 4 to 6 δ 15 N-NH + 4 values were higher at the end of the dark incubation at 08.05 am
than in the other three chambers and more variable. Values were highest in chamber 6 (2.3 ‰)
and 4 (1.9 ‰). Those two chambers also showed the lowest seepage rates and lowest
ammonium flux (Table 3.8, Figure 3.11B). δ 15 N-NH +
4 values were increasing in both
chambers during the light incubation from 08.05 to 16.30. Benthic chamber 5 had the highest
seepage rates but low ammonium flux. The δ 15 N-NH + 4 value at the end of the dark incubation
was 1.3 ‰ and decreased during the light incubation down to 0.9 ‰.