Introduction: the role of fluorescence in water quality

analysis

What is Fluorescence?Fluorescence is a type of luminescence.

(1) A molecule absorbs a high-energy photon…

(2) …and re-emits a lower-energy photon with a longer wavelength (fluorescence).

(3) Usually the absorbance is in the ultraviolet, and the emitted light is in the visible range, but this depends on the particular molecule.

Fluorescent molecules

potentially found in the

water environment

Naphthalene

Proteins

Stilbenes

Chlorophyll

‘Humic’ matter

Phenols

We can now ‘map’ fluorescence.

The above ‘map’ shows fluorescence intensities of an untreated wastewater at different locations in ‘optical space’. Organic molecules in the wastewater are fluorescing.

Y-axis: excitation energy. X-axis: emitted fluorescence wavelength. Z-axis: fluorescence intensity.

Time taken: < 1 minute. Greater sensitivity than absorbance.

300 400 500 600 7000

200

400

600

800

1000

Wavelength (nm)

Inte

nsity (

a.u

.)

Wa

ve

le

ng

th

(

nm

)

W a v e l e n g t h ( n m )

2 0 0 . 0 0

2 5 0 . 0 0

3 0 0 . 0 0

3 5 0 . 0 0

4 0 0 . 0 0

4 5 0 . 0 0

5 0 0 . 0 0

5 5 0 . 0 0

6 0 0 . 0 0

3 0 0 .0 0 3 5 0 .0 0 4 0 0 .0 0 4 5 0 .0 0 5 0 0 .0 0 5 5 0 .0 0 6 0 0 .0 0 6 5 0 .0 0 7 0 0 .0 0

9 6 2 . 0 0

8 8 6 . 0 0

8 1 0 . 0 0

7 3 4 . 0 1

6 5 8 . 0 1

5 8 2 . 0 1

5 0 6 . 0 1

4 3 0 . 0 1

3 5 4 . 0 2

2 7 8 . 0 2

2 0 2 . 0 2

1 2 6 . 0 2

5 0 . 0 2

- 2 5 . 9 7

Organic matter fluorescence signatures

300 400 500 600 7000

200

400

600

800

1000

Wavelength (nm)

Inte

nsity (

a.u

.)

W

av

el

en

gt

h

(n

m)

W a v e l e n g t h ( n m )

2 0 0 . 0 0

2 5 0 . 0 0

3 0 0 . 0 0

3 5 0 . 0 0

4 0 0 . 0 0

4 5 0 . 0 0

5 0 0 . 0 0

5 5 0 . 0 0

6 0 0 . 0 0

3 0 0 .0 0 3 5 0 .0 0 4 0 0 .0 0 4 5 0 .0 0 5 0 0 .0 0 5 5 0 .0 0 6 0 0 .0 0 6 5 0 .0 0 7 0 0 .0 0

9 6 2 . 0 0

8 8 6 . 0 0

8 1 0 . 0 0

7 3 4 . 0 1

6 5 8 . 0 1

5 8 2 . 0 1

5 0 6 . 0 1

4 3 0 . 0 1

3 5 4 . 0 2

2 7 8 . 0 2

2 0 2 . 0 2

1 2 6 . 0 2

5 0 . 0 2

- 2 5 . 9 7

Humic / fulvicsubstances

Fluorescentwhitening agents

Microbialmaterial

FluorescentDyes

Chlorophyll

1990 1992 1994 1996 1998 2000 2002 2004 2006

0

10

20

30

40

50

60

Num

ber

of papers

publis

hed p

er

year

Year

Journal papers with keywords "fluorescence and river and organic"

Journal papers with keywords "fluorescence" and wastewater and organic"

Rapid increase in academic publications

First ‘optical map’published (marine science)

First ‘optical map’(fresh and waste water)

Rapid technologicalimprovements

Improvements in technology

Excitation now possible in short UV (200-300 nm). 1990s limit was mid-UV; 1980s was long-UV.

Mass produced instruments.

Competitive market, off the shelf instruments with excellent software and accessories.

Appropriate analysis time.

A <1 minute ‘optical map’ today took ~15 mins (1990s) and ~2 hrs (1980s).

Increased portability.

LED sources, improved detectors, lighter batteries. Ongoing in 2000s

300 350 400 450 5000

200

400

600

800

1000

Wavelength (nm)

Inte

nsity (

a.u

.)

Wa

ve

le

ng

th

(

nm

)

W a v e l e n g t h ( n m )

2 2 5 . 0 0

2 5 0 . 0 0

2 7 5 . 0 0

3 0 0 . 0 0

3 2 5 . 0 0

3 5 0 . 0 0

3 7 5 . 0 0

4 0 0 . 0 0

3 0 0 . 0 0 3 2 5 . 0 0 3 5 0 . 0 0 3 7 5 . 0 0 4 0 0 . 0 0 4 2 5 . 0 0 4 5 0 . 0 0 4 7 5 . 0 0 5 0 0 . 0 0

9 6 3 . 0 9

8 8 9 . 2 7

8 1 5 . 4 5

7 4 1 . 6 3

6 6 7 . 8 2

5 9 4 . 0 0

5 2 0 . 1 8

4 4 6 . 3 6

3 7 2 . 5 4

2 9 8 . 7 2

2 2 4 . 9 0

1 5 1 . 0 8

7 7 . 2 7

3 . 4 5

Fluorescence as a chemical water quality surrogate.

Surrogate for BOD in wastewater treatment.

Surrogate for TOC in drinking water treatment.

Surrogate for Chl-a in drinking water protection.

Process control:

Monitoring FWA fluorescence in wastewater treatment

Monitoring NOM fluorescence in drinking water treatment

Fluorescence as a rapid method of characterising organic matter

chemistry (aromacity, molecular weight) and function (metal binding,

hydrophobicity).

300 400 500 600 7000

200

400

600

800

1000

Wavelength (nm)

Inte

nsity (

a.u

.)

Wa

ve

le

ng

th

(

nm

)

W a v e l e n g t h ( n m )

2 0 0 . 0 0

2 5 0 . 0 0

3 0 0 . 0 0

3 5 0 . 0 0

4 0 0 . 0 0

4 5 0 . 0 0

5 0 0 . 0 0

5 5 0 . 0 0

6 0 0 . 0 0

3 0 0 .0 0 3 5 0 .0 0 4 0 0 .0 0 4 5 0 .0 0 5 0 0 .0 0 5 5 0 .0 0 6 0 0 .0 0 6 5 0 .0 0 7 0 0 .0 0

9 6 2 . 0 0

8 8 6 . 0 0

8 1 0 . 0 0

7 3 4 . 0 1

6 5 8 . 0 1

5 8 2 . 0 1

5 0 6 . 0 1

4 3 0 . 0 1

3 5 4 . 0 2

2 7 8 . 0 2

2 0 2 . 0 2

1 2 6 . 0 2

5 0 . 0 2

- 2 5 . 9 7

General water quality applications

Fluorescence as a chemical water quality surrogate.

Surrogate for BOD in wastewater treatment.

Surrogate for TOC in drinking water treatment.

Surrogate for Chl-a in drinking water protection.

Process control:

Monitoring FWA fluorescence in wastewater treatment

Monitoring NOM fluorescence in drinking water treatment

Fluorescence as a rapid method of characterising organic matter

chemistry (aromacity, molecular weight) and function (metal binding,

hydrophobicity).

300 400 500 600 7000

200

400

600

800

1000

Wavelength (nm)

Inte

nsity (

a.u

.)

Wa

ve

le

ng

th

(

nm

)

W a v e l e n g t h ( n m )

2 0 0 . 0 0

2 5 0 . 0 0

3 0 0 . 0 0

3 5 0 . 0 0

4 0 0 . 0 0

4 5 0 . 0 0

5 0 0 . 0 0

5 5 0 . 0 0

6 0 0 . 0 0

3 0 0 .0 0 3 5 0 .0 0 4 0 0 .0 0 4 5 0 .0 0 5 0 0 .0 0 5 5 0 .0 0 6 0 0 .0 0 6 5 0 .0 0 7 0 0 .0 0

9 6 2 . 0 0

8 8 6 . 0 0

8 1 0 . 0 0

7 3 4 . 0 1

6 5 8 . 0 1

5 8 2 . 0 1

5 0 6 . 0 1

4 3 0 . 0 1

3 5 4 . 0 2

2 7 8 . 0 2

2 0 2 . 0 2

1 2 6 . 0 2

5 0 . 0 2

- 2 5 . 9 7

Fluorescence as a chemical water quality surrogate.

Surrogate for BOD in wastewater treatment.

Surrogate for TOC in drinking water treatment.

Surrogate for Chl-a in drinking water protection.

Process control:

Monitoring FWA fluorescence in wastewater treatment

Monitoring NOM fluorescence in drinking water treatment

Fluorescence as a rapid method of characterising organic matter

chemistry (aromacity, molecular weight) and function (metal binding,

hydrophobicity).

300 400 500 600 7000

200

400

600

800

1000

Wavelength (nm)

Inte

nsity (

a.u

.)

Wa

ve

le

ng

th

(

nm

)

W a v e l e n g t h ( n m )

2 0 0 . 0 0

2 5 0 . 0 0

3 0 0 . 0 0

3 5 0 . 0 0

4 0 0 . 0 0

4 5 0 . 0 0

5 0 0 . 0 0

5 5 0 . 0 0

6 0 0 . 0 0

3 0 0 .0 0 3 5 0 .0 0 4 0 0 .0 0 4 5 0 .0 0 5 0 0 .0 0 5 5 0 .0 0 6 0 0 .0 0 6 5 0 .0 0 7 0 0 .0 0

9 6 2 . 0 0

8 8 6 . 0 0

8 1 0 . 0 0

7 3 4 . 0 1

6 5 8 . 0 1

5 8 2 . 0 1

5 0 6 . 0 1

4 3 0 . 0 1

3 5 4 . 0 2

2 7 8 . 0 2

2 0 2 . 0 2

1 2 6 . 0 2

5 0 . 0 2

- 2 5 . 9 7

Fluorescence as a chemical water quality surrogate.

Surrogate for BOD in wastewater treatment.

Surrogate for TOC in drinking water treatment.

Surrogate for Chl-a in drinking water protection.

Process control:

Monitoring FWA fluorescence in wastewater treatment

Monitoring NOM fluorescence in drinking water treatment

Fluorescence as a rapid method of characterising organic matter

chemistry (aromacity, molecular weight) and function (metal binding,

hydrophobicity).

300 400 500 600 7000

200

400

600

800

1000

Wavelength (nm)

Inte

nsity (

a.u

.)

Wa

ve

le

ng

th

(

nm

)

W a v e l e n g t h ( n m )

2 0 0 . 0 0

2 5 0 . 0 0

3 0 0 . 0 0

3 5 0 . 0 0

4 0 0 . 0 0

4 5 0 . 0 0

5 0 0 . 0 0

5 5 0 . 0 0

6 0 0 . 0 0

3 0 0 .0 0 3 5 0 .0 0 4 0 0 .0 0 4 5 0 .0 0 5 0 0 .0 0 5 5 0 .0 0 6 0 0 .0 0 6 5 0 .0 0 7 0 0 .0 0

9 6 2 . 0 0

8 8 6 . 0 0

8 1 0 . 0 0

7 3 4 . 0 1

6 5 8 . 0 1

5 8 2 . 0 1

5 0 6 . 0 1

4 3 0 . 0 1

3 5 4 . 0 2

2 7 8 . 0 2

2 0 2 . 0 2

1 2 6 . 0 2

5 0 . 0 2

- 2 5 . 9 7

Fluorescence as a chemical water quality surrogate.

Surrogate for BOD in wastewater treatment.

Surrogate for TOC in drinking water treatment.

Surrogate for Chl-a in drinking water protection.

Process control:

Monitoring FWA fluorescence in wastewater treatment

Monitoring NOM fluorescence in drinking water treatment

Fluorescence as a rapid method of characterising organic matter

chemistry (aromacity, molecular weight) and function (metal binding,

hydrophobicity).

300 400 500 600 7000

200

400

600

800

1000

Wavelength (nm)

Inte

nsity (

a.u

.)

Wa

ve

le

ng

th

(

nm

)

W a v e l e n g t h ( n m )

2 0 0 . 0 0

2 5 0 . 0 0

3 0 0 . 0 0

3 5 0 . 0 0

4 0 0 . 0 0

4 5 0 . 0 0

5 0 0 . 0 0

5 5 0 . 0 0

6 0 0 . 0 0

3 0 0 .0 0 3 5 0 .0 0 4 0 0 .0 0 4 5 0 .0 0 5 0 0 .0 0 5 5 0 .0 0 6 0 0 .0 0 6 5 0 .0 0 7 0 0 .0 0

9 6 2 . 0 0

8 8 6 . 0 0

8 1 0 . 0 0

7 3 4 . 0 1

6 5 8 . 0 1

5 8 2 . 0 1

5 0 6 . 0 1

4 3 0 . 0 1

3 5 4 . 0 2

2 7 8 . 0 2

2 0 2 . 0 2

1 2 6 . 0 2

5 0 . 0 2

- 2 5 . 9 7

Fluorescence as a chemical water quality surrogate.

Surrogate for BOD in wastewater treatment.

Surrogate for TOC in drinking water treatment.

Surrogate for Chl-a in drinking water protection.

Process control:

Monitoring FWA fluorescence in wastewater treatment

Monitoring NOM fluorescence in drinking water treatment

Fluorescence as a rapid method of characterising organic matter

chemistry (aromacity, molecular weight) and function (metal binding,

hydrophobicity).

300 400 500 600 7000

200

400

600

800

1000

Wavelength (nm)

Inte

nsity (

a.u

.)

Wa

ve

le

ng

th

(

nm

)

W a v e l e n g t h ( n m )

2 0 0 . 0 0

2 5 0 . 0 0

3 0 0 . 0 0

3 5 0 . 0 0

4 0 0 . 0 0

4 5 0 . 0 0

5 0 0 . 0 0

5 5 0 . 0 0

6 0 0 . 0 0

3 0 0 .0 0 3 5 0 .0 0 4 0 0 .0 0 4 5 0 .0 0 5 0 0 .0 0 5 5 0 .0 0 6 0 0 .0 0 6 5 0 .0 0 7 0 0 .0 0

9 6 2 . 0 0

8 8 6 . 0 0

8 1 0 . 0 0

7 3 4 . 0 1

6 5 8 . 0 1

5 8 2 . 0 1

5 0 6 . 0 1

4 3 0 . 0 1

3 5 4 . 0 2

2 7 8 . 0 2

2 0 2 . 0 2

1 2 6 . 0 2

5 0 . 0 2

- 2 5 . 9 7

Next....

So we now know what energy is needed to excite fluorescence in water samples.

What is the science of fluorescence? How is it measured?