Fluorescence Indices and Their Interpretation
327
7
6
5
Chla (µg L
–1
)
4
(a)
3
2
1
0
1.8
1.5
1.2
DOC (mg L –1
)
0.9
(b)
(c)
(d)
(e)
0.6
0.3
0.0
100
80
60
%FA
40
20
0
1.8
1.7
1.6
PLFA
SRFA
13 May
2 2 June
01 Aug
Date
10 Sept
20 Oct
1.5
FI
1.4
1.3
1.2
0.55
0.50
0.45
0.40
RI
0.35
0.30
0.25
Figure 9.13. Seasonal variation in (a) chlorophyll (b) DOC, (c) percentage fulvic acid, (d) whole
water (solid line) and fulvic acid (dashed line) McKnight Fluorescence Index (FI), and (e) whole
water redox index (RI) at the outlet to Green Lake 4, an alpine lake in the Colorado Rocky Mountains.
The vertical dashed lines indicate the sustained rain event, and the shaded areas represent the timing of the peak in chlorophyll a at the outlet. PLFA represents the FI of the Pony Lake fulvic acid, a
microbial end member, and SRFA represents the FI of the Suwannee River fulvic acid, a terrestrial
end member. (Adapted from Miller et al., 2009.)