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