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1.41
(a)
r 2 = 0.81
p < 0.001
1.36
1.31
1.26
y = 0.0031x + 1.24
1.21
0
5
10
15
20
25
30
35
40
45
Continuous cropland in riparian zone (%)
1.41
(b)
r 2 = 0.69
p < 0.001
1.36
1.31
1.26
y = -0.0132x + 1.36
1.21
0
1
2345678
Wetland in riparian zone SQRT %)
Figure 3.8. Relationships between indices of DOM character and landcover. The best predictors
for fluorescence index (a,b) . (Reprinted from Wilson and Xenopoulos, 2009 , by permission from
Macmillan Publishers Ltd: Nature Geoscience .)
be utilized to provide information about environmental conditions and the biogeochemical
transformations that are taking place, which is very informative in studies examining nutri-
ent cycling in hyporheic and riparian ecosystems (Fellman et al., 2010 ).
Protein-like fluorescence has been linked to biological labile DOM in a range of fresh-
water ecosystems. For example, a study in Lakes of Southern Quebec by Cammack et al.
( 2004 ) correlated protein-like fluorescence with bacterial production, bacterial respiration,
and community respiration. Laboratory incubation experiments from a diverse range of
freshwater DOM sources have also found strong relationships between protein-like fluo-
rescence and biodegradable DOM (Fellman et al., 2009b ; Hood et al., 2009 ). Protein-like
fluorescence can also be used with respect to examining in stream uptake of DOM as
Fellman et al. ( 2009c ) demonstrated that protein-like fluorescence decreased downstream
during soil leachate addition experiments in forested headwater streams in Alaska (USA).
In this leachate addition experiment, humic-like fluorescence did not change and protein-
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