Presentation given by John Quinton, Lancaster Environment Centre, Lancaster University, at the workshop on Sediment Fluxes in Irish Rivers (Siltflux Workshop) = 28/10/14, UCD, Dublin 4

1. John Quinton
Lancaster Environment Centre
Lancaster University
NOVEL APPROACHES TO SEDIMENT
TRACING
Environment
Centre

2. Environment
Centre
ACKNOWLEDGEMENTS
• Jack Poleykett and Rob Hardy
• Alona Armstrong, Mike Coogan, Barbara
Maher, Jackie Pates (Lancaster University)
and Kevin Black (Partrac Ltd) Debbie Hurst
(confocal microscopy), Mike James (image
analysis).
Environment
Centre
Clay work funded by NERC Grant: NE/J017795/1

3. Environment
Centre
BACKGROUND
• Working on diffuse pollution
and erosion for 25 years
• Modelling processes
• Practical mitigation measures
• Our ability to conceptualise
processes runs ahead of our
ability to measure them

4. Environment
Centre
PARTICLE TRACKING (SEDIMENT TRACING)
• Our aim
• To develop methologies and methods to
determine the source-sink relationships
(transport pathways), the depositional footprint
and rates of sediment transport through the
environment.
• How?
• Using natural and artificial sediment that has
been ‘tagged’ or ‘marked’ with an identifiable
signature. These are called tracers
Images courtesy, Partrac Ltd

5. Environment
Centre
SEDIMENT TRACING
• Why would it be useful
to have a sediment
tracer?
• Improve the
understanding of
transport processes
• Evaluate in - field
mitigation techniques
• Develop and validate
soil erosion and
transport models

6. Environment
Centre
Bind to everything
Adding radiation to
environment is
unethical
Density metal ≠ density clay
Not that rare
ICP-MS £15 per sample Density plastic ≠ density clay
Soil is also fluorescent at
similar wavelength
Radionuclides i.e. 137Cs
What's been tried
Rare Earths Fluorescent microspheres

7. Environment
CentreWHAT I’M NOT GOING
TO TALK ABOUT
• Sediment fingerprinting
• Fallout and cosmogenic radionuclide
• Caffeine or plant molecules
• C14

8. Environment
Centre
• Focus on two tracers
• Commercial dual signature tracer for
particles >20 μm
• Development of new fluorescent tracer
for particles <20 μm

9. Environment
Centre
• To assess the properties and behaviour of the
tracer
• To assess the potential of conducting non-
intrusive mapping of the spatial distribution
of dual signature tracer particles
COMMERCIAL DUAL SIGNATURE
TRACER

10. Environment
Centre
THE TRACER
Photomicrograph
Magnet saturated with tracer
particles
Images courtesy, Partrac Ltd

11. Environment
Centre
LAB EXPERIMENT

12. Environment
Centre
HOW SIMILAR ARE THE SOIL AND
TRACER PROPERTIES?
98
%
1.2
%
0.3
%
0.3
%
0.2
%
< 63 125 250 500 1000
Outdoor simulations: particle size distribution ( % ) of the native soil
Particle density ( kg/m3 ± 115 kg/m3 ) - Percentage difference ranged from 3 – 6 %

13. Environment
Centre
HOW DOES THE TRACER BEHAVE? AND,
HOW EFFECTIVELY CAN IT BE TRACKED?
)
Location of the Core
sample
Run-off collection
Tracer deployment
zone
A schematic diagram of the soil box sampling design
25 cm
12.5 cm
Simulated rainfall
Rate - 31 mm h–1
Slope - 10 %
O.3 %Section 1
Section 3
Section 4
Section 5
18 %
0.9 %
0.6 %
0.5 %
Section 2

14. Environment
Centre
• Winton Hill - Sandy loam
• Myerscough – silt loam
• Hazelrigg – Clay loam
HOW MUCH TRACER WAS
RECOVERED FROM THE RUN-OFF?
The mean percentage (%) mass recovered from the collected run-off from the three soils following the
deployment of different tracer size fractions.

15. Environment
Centre
A plot of the dry tracer mass (g) recovered from a shallow core Vs the low frequency magnetic
susceptibility of the core captured from the surface.
Can the spatial distribution of the tracer
particles be mapped using magnetic
susceptibility (KLF) ?

16. Environment
Centre
FLUORESCENCE IDENTIFICATION
AND PHOTOGRAPHY
Mapping of the spatial distribution of tracer particles following an overland flow event (8 L p/min) using
photography under blue light ( ̴ 395 nm) illumination.
Erosion plot Pre – event Post event
2.75 m
0.5 m

17. Environment
Centre
25 cm
25 cm

18. Environment
Centre
CONCLUSION
‘Dual signature’ tracer provides a particulate tracer that:
• Mimics the particle size and density of the native soil
• Can be effectively deployed, monitored and recovered over
significant temporal and spatial scales
• Enables semi-quantitative spatial mapping of the distribution of
tracer particles and quantitative determination of tracer mass

19. BUT NO GOOD FOR THE CLAY FRACTION

20. Environment
Centre
• No commercial tracers with same
properties
• Some attemps with paraquat and long
chain organic molecules but expensive
and disruptive
• Use of surrogates e.g. fluorescent
microspheres

21. Environment
Centre
To create a fluorescent clay tracer which we
could track in real time through a rain storm
AIM

22. Environment
Centre
LABELLING CLAY
+

23. Environment
Centre
THE RESULT
Before After
Average size = 1.9
microns

24. Environment
Centre
LIGHTING IT UP
RAINFALL

25. Environment
Centre
ACQUIRING IMAGES
Soil box
DSLR
camera
570 nm
long pass
filterCamera
settings
~6 second
exposure
F-stop 1.8
15M
RAW + JPEG
50mm fixed
focus lens

26. Environment
Centre
0 Seconds 262 Seconds 2252 Seconds
True colour images
from camera
False
colour
images
created
using [r]

27. Environment
Centre
Data processed on a pixel by pixel basis using [r]
Black = Lower
tracer front
Red= Upper
tracer front
HIGH RESOLUTION DATA
Bottom of
soil box
Top of
soil box

28. Environment
Centre
Blue = RHS of soil box
Red = LHS of soil boxEdges of
soil box

29. Environment
Centre
CONVERSION IN TIME LAPSE FILM

30. Environment
Centre
• Novel tracer
• High tracer/clay similarity
• Cheap and easy to synthesize
• Real time recording of data
• Rapid data processing using [r]
• No need to remove material when sampling
• Quick and cheap
MAJOR ADVANTAGES

31. Environment
Centre
• Non-disruptive quantification of the
tracers
• In lab and in field
• Applications to erosion monitoring
• Development of new clay tracers
NEXT STEPS