Geoscience Reference
In-Depth Information
1.0
aug
0.9
jun
River North Ty ne
River Derwent
Swin Burn
Wallish Walls Burn
River Don
Black Burn
0.8
mar
mar
0.7
0.6
may
aug
jun
0.5
jan
jan
may
0.4
aug
mar
mar
nov
nov
jan
jun
mar
jun
aug
0.3
nov
mar
may
nov
jan
jan
jan
jun
jun
0.2
may
may
nov
aug
may
nov
0.1
aug
0.0
410
415
420
425
430 435
Peak C emissions wavelength (nm)
440
445
450
455
460
465
Figure 9.8. Example of the use of the peak T/peak C ratio to characterize river water samples, here
graphed against the wavelength of maximum peak C emission. Samples are from the Tyne catch-
ment, NE England over an annual sampling campaign 2002-2003. The North Tyne and Black
Burn, upland peat-rich catchments, are characterized by a low peak T/peak C ratio and high peak
C emission wavelength, considered to be a natural water signal. The more impacted lowland catch-
ments - the Wallish Walls Burn, with intensive agriculture, and the Rivers Don and Derwent, two
urbanized catchments - have lower peak C emission wavelengths and a greater range of peak T/peak
C, though the ratio is generally higher than in un-impacted upland rivers. This shows the utility of the
peak T/peak C index for identifying the influence of wastewater on rivers. (From Hudson et al.
[
2007
], with minor adjustments.)
peak T/peak C ratio of around 1.0, showing a distinctive fluorescence EEM with high
protein-like and fulvic-like peaks in approximately equal ratio. Downstream of the sewage
discharge the EEMs continued to show the discharge signal, with the ratio slowly decreas-
ing due to dilution effects.
Subsequent research has demonstrated that peak T fluorescence intensity is strongly
correlated with biological oxygen demand in both river waters and final treated sewage
effluents (Hudson et al.,
2008
). Together with the observation that peak C fluorescence
intensity correlates with dissolved organic matter concentration for individual rivers, the
peak T/peak C ratio can be conceptualized as a BOD/DOC ratio in terrestrial waters, and
therefore related to water quality.
Figure 9.8
presents the peak T/peak C ratio for some
sub-catchments of the River Tyne, UK (Hudson et al.,
2007
) showing a contrast between
upland catchments of good water quality and lowland, urban catchments of poor qual-
ity. The microbial sources of peak T fluorescence need not be limited to sewage-derived
