Jökull - 01.12.2006, Page 35
The stable isotopic (C and N) composition of modern plants and lichens from northern Iceland
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-14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
Torfadalsvatn
Stífluvatn
Arnarvatn stóra
Lake Plants (aquatic and
terrestrial) and lichens
sediments
d15N(‰, air)
d
13
C
(‰
,
V
P
D
B
)
Surface sediments
Aquatic plants
Terrestrial plants and lichens
Litla-Viðarvatn
Figure 3. The δ13C and δ15N of plants, lichens and surface sediment samples from four lakes in Iceland. –
Magn kolefnis og köfnunarefnis í setkjörnum úr vötnum á 2. mynd.
plants (such as HCO−3 and dissolved CO2), active
uptake of inorganic carbon HCO−3 for carbon
assimilation, different photosynthetic pathways (C3
and C4), photosynthetic rate, and different diffusional
resistances from the unstirred boundary layer around
the leaves of aquatic macrophytes (Keeley and
Sandquist, 1992). The δ13C of surface sediment
samples from the four lakes (Figure 3) appears to
resemble the composition of the terrestrial plants from
these sites. However, one end member that was not
collected due to the field season (i.e. spring/winter)
was phytoplankton, which can have a δ13C value
similar to terrestrial plants (Figure 1). The sources
of material composing the surface sediments analyzed
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