use of in situ uv fluorometry for water catchment monitoring · parameter pah fuel pah cdom 255...
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Use of in situ UV fluorometry for water catchment monitoring
Dr Cathy Rushworth
Chelsea Technologies Group
18th March 2015
Overview
• Target markers
• Multi-wavelength UV fluorometry of natural
water samples
• Fluorometer standardisation
• Background correction
• Examples
Target markers
• Fuel
• Polycyclic aromatic hydrocarbons
• Tryptophan
• Optical brighteners
Phenanthrene
BTEX
FWA-5
Tryptophan
• Tryptophan sensor reports
fluorescence in ppb Tryptophan,
as determined via calibration of
pure tryptophan in deionised
water
1 µM Tryptophan
The development of a fluorescence sensor for
monitoring microbial processes of freshwater
systems
UV fluorescence in freshwaters
• Peak C: 350ex/450em (Humic-like)
• Peak T: 275ex/340em (Tryptophan-like)
• Peak A: 230ex/420em (Humic-like)
P. G. Coble, Marine Chemistry, 51, 325-346 (1996)
Reservoir Canal
T
C
A
CDOM calibration
100 ppb PTSA
• Water soluble, stable, non-
toxic, also used as tracer
• CDOM sensor is calibrated to
report fluorescence in ppb
PTSA
Fluorometer standardisation
• NIST-traceable, certified reference
material
• Fluorescence reported in QSU
where 1 QSU is equivalent to the
fluorescence intensity recorded
from 1 ppm quinine sulphate at
λex = 347.5 nm, λem = 450 nm
Blue line: Aqualog
Orange line: Cal. Cert.
UviLux specifications
Parameter PAH
Fuel
PAH CDOM
255
Tryptophan CDOM
280
Optical
Brightener
Sensitivity / QSU0.0015 0.0004 0.0008
Calibrated range
/ QSU 24 12 50
Example
compound:
Sensitivity -
Range / ppb
BTEX*:
3.0 - 50,000
NDSA**
0.40 - 6,500
Carbazole:
0.005 - 80
Phenanthrene:
0.010 - 150
Perylene:
0.003 - 50
Tryptophan:
0.02 - 600
PTSA:***
0.02 - 400
PTSA:***
0.04 - 2,400
*BTEX is Benzene, Toluene, Ethylbenzene, p-Xylene, m-Xylene, o-Xylene at equal ppb
concentrations
**NDSA is naphthalene disulphonic acid
***PTSA is pyrene tetrasulphonic acid
Tryptophan & CDOM
• Tryptophan conversion
factor: 0.0199 QSU ppb-1
• CDOM conversion factor:
0.0307 QSU ppb-1
• Equal sensitivity in terms
of QSU, CDOM 1.54 times
more sensitive in terms of
ppb
BACTI-Wader Pro system
• UviLux Tryptophan & CDOM
• Dual-Lux dongle
• Hawk hand-held data logger
Example T/C fluorescence ratios
Ref. F1 – Tryptophan
Indicator of
microbial activity
F2 – CDOM
Provides stable
baseline
Comments on the ratio F1/F2
Baker 2001 276 - 281ex
340 - 370em
326 – 339ex
414 - 422em
EEM of STW outflows - Treated effluent ~1.0
Untreated sewage 2.7 – 3.1 in river waters
Baker 2002 275ex
350em
320 - 240ex
410 - 430em
EEM of farm wastes: silage liquor > 20, cattle/pig slurries
~2-5, sheep barn wastes ~0.5 – 4
Reynolds
2002
280ex
350em
280ex
440em
Not used as ratio, but correlate 350 nm to biodegradable
and 440 nm to non-biodegradable DOM through STW
Henderson et
al. 2009
275ex
340em
300 - 370ex
400 - 500em
Review
Ghervase et
al. 2010
266ex
300-350em
266ex
410-460em
Emission scans using laser excitation
~ 0.3 clean water
> 2 sewage impacted rivers
Guo et al.
2010
275ex
339em
380ex
467em
EEM-PARAFAC study
Marker of sewage
Stedmon et
al. 2011
270 - 290ex
325 - 350em
270 - 290ex
480 - 505em
EEM-PARAFAC study
Monitoring drinking water quality, indicator of microbial
contamination
A. Baker, Environ. Sci. Technol., 35, 948-953 (2001); A. Baker, Water Research, 36, 189-195 (2002); D. M. Reynolds, J. Chem. Technol. & Biotechnol., 77, 965-
972 (2002); R. K. Henderson, A. Baker, K. R. Murphy, A. Hambly, R. M. Stuetz, S. J. Khan, Water Research, 43, 863-881 (2009); L. Ghervase, E. M. Carstea, G.
Pavelescu, D. Savastru, R. Rep. Phys., 62(3), 652-659 (2010); W. Guo, J. Xu, J. Wang, Y. Wen, J. Zhuo, Y. Yan, J. Env. Sci., 22(11), 1728-1734 (2010); C. A.
Stedmon, B. Seredyńska-Sobecka, R. Boe-Hansen, N. Le Tallec, C. K. Waul, E. Arvin, Water Research, 45, 6030-6038 (2011)
Local Tryptophan/CDOM levels
• Tryp/CDOM - JA
Sample 5
Sample 6
Sample 3
Sample 4
Sample 1
Sample 2
Chelsea Technologies
EEMs of local samples
Sample 1 Sample 2
λex = 280 nm
WwTW event detection
BOD/CDOM ratio smoothes out daily variation making Tryptophan peaks clearer
0
50
100
150
200
250
300
13/10 15/10 17/10 19/10 21/10 23/10 25/10 27/10 29/10 31/10 02/11 04/11 06/11 08/11 10/11
DATE
[TR
YP
TO
PH
AN
] (u
g/l
)
0
2
4
6
8
10
12
UV
ILU
X C
DO
M (
ug
/l)
Tryptophan/CDOM
diurnal correlation
Tryptophan anomalies
No cleaning during
this time frame
35
34 34
WwTW event detection
BOD/CDOM ratio smoothes out daily variation making Tryptophan peaks clearer
PEN-Y-BONT WATER TREATMENT WORKS
Overnight 6-7/11/2013
0
2
4
6
8
10
12
14
06/11
06:00
06/11
09:00
06/11
12:00
06/11
15:00
06/11
18:00
06/11
21:00
07/11
00:00
07/11
03:00
07/11
06:00
07/11
09:00
07/11
12:00
07/11
15:00
07/11
18:00
DATE
UV
ILU
X B
OD
/ U
VIL
UX
CD
OM
0
10
20
30
40
50
60
70
80
90
LA
B B
OD
5 (
mg
/l)
UviLux BOD
UviLux CDOM
Lab BOD
Similar rise in both
sensor and lab resultsCDOM signal attenuated by
Tryptophan absorbance
Tryptophan peak
correlating with BOD5
& bacterial counts
E.Coli:
74,000 cfu/100ml
Enterococci:
22,000 cfu/100ml
35
34 34
Tryptophan/CDOM ratio
BOD/CDOM ratio smoothes out daily variation making Tryptophan peaks clearer
0
50
100
150
200
250
300
13/10 15/10 17/10 19/10 21/10 23/10 25/10 27/10 29/10 31/10 02/11 04/11 06/11 08/11 10/11
DATE
[TR
YP
TO
PH
AN
] (u
g/l
)
0
50
100
150
200
250
300
TR
YP
TO
PH
AN
/ C
DO
M
Ratio smoothes diurnal variation,
but anomalies are still clear
35
Fluorescence & Turbidity
BOD/CDOM ratio smoothes out daily variation making Tryptophan peaks clearer
35
34 34
85
113
93
324
45
Single Tryptophan sensor
Conclusions
• In situ UV fluorometers can be configured to target a
range of water quality markers
• Single fluorescence sensor can be used locally to trace
pollution sources or highlight deviations from baseline
in installations
• Site-to-site comparison of absolute fluorescence
intensities requires background CDOM fluorescence
correction
• OB monitoring is particularly susceptible to CDOM
background