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Wilson Tadeu Lopes da Silva1, Débora Marcondes Bastos Pereira Milori1, Ladislau Martin-Neto1,2, Adolpho José Posadas1,3, Aline Segnini1,3, Roberto
Quiroz3
1- Brazilian Agricultural Research Corporation (Embrapa) – Embrapa AgriculturalInstrumentation Center – São Carlos/SP, Brazil.
2- Virtual Laboratories of Embrapa abroad – Labex – Beltsville/MD, USA3- International Potato Center (CIP) – Lima, Peru.
Rome – Italy
13 July 2010
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• Does the determination of Carbon content in the soil, satisfactory for analysis of balance of carbon in agriculture areas?
• Do the actual laboratory analyses adequate in terms of practice, representativity, costs, etc.?
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Our proposalOur proposal
•To use Fluorescence parameters to produce a quick indicator for changes in structure of SOM;
•Measure this indicator using whole soil;
We built an apparatus to evaluate the feasibility of using laser-induced fluorescence spectroscopy (LIFS) for whole soil analysis
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PortablePortable LaserLaser--InducedInduced FluorescenceFluorescenceSpectroscopeSpectroscope
Optical BunddleProfile
Excitation Fibers
Emission Fiber
Laser
Miniature spectrometer
Filter
Optical bunddle
Lap-top
soil
Miniature spectrometer
Segnine, A.; Milori, D.; et al. Spectroscopic assessment of soil organic matter in wetlands from the high Andes, accepted in Soil Science Society of America Journal
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Portable LIFS systemPortable LIFS system
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Portable LIFS systemPortable LIFS system
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LaserLaser--Induced Fluorescence SpectroscopyInduced Fluorescence Spectroscopy
400 450 500 550 600 650 700
0
1
2
3
NATURAL SOIL HEATED SOIL (600°C)
Inte
nsity
(a.u
.)
λ (nm)
HLIF = AreaC
Milori et al.. Soil Science Society of America Journal 70 (1): 57-63 JAN-FEB 2006
HLIF = Humification Index
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LaserLaser--Induced Fluorescence SpectroscopyInduced Fluorescence Spectroscopy
0.05 0.10 0.15 0.20 0.25 0.300.5
1.0
1.5
2.0
2.5
3.0
R=0.85; P<0.0001
HLI
F ( W
hole
Soi
l)
A4/A1 (HA in solution)
Milori et al.. Soil Science Society of America Journal 70 (1): 57-63 Jan-Feb 2006Segnini, A.; Milori, D.; et al. Soil Science Society of America Journal. Acepted to be published.
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Sample preparationSample preparation
soil samples from
experimental areamanual cleaning,
and after the samples are sieved
15 ton of
pressure3 pellets of
each sample(1 g)
Cost equipment ~ US$ 30.000,00
Cost / Analysis : US$ 0.50
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Portable LIFS systemPortable LIFS system
AdvantagesAdvantages
- Faster and cleaner process;- Low cost;- It is possible a large scale measurements;- Allow analyses of SOM near its natural state;- Contribution of Humin is taking into account in the analyses;- To allow evaluation of changes in SOM according to soil management.
DisadvantagesDisadvantages
- It is not a selective technique. It is difficult to identify structures;- Quenching effect due to interaction with metal can occur;- For organic soils it is necessary to take care with Inner Filter Effect.
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To quantify soil carbon in a clean and agile To quantify soil carbon in a clean and agile way using methods economically viable way using methods economically viable
Determination by Near Infrared Spectroscopy (NIRS)Determination by Near Infrared Spectroscopy (NIRS)Texture (Sand, Clay, and Silt)Texture (Sand, Clay, and Silt)Soil organic matterSoil organic matterMicrobial activityMicrobial activity
Determination by Laser Induced Breakdown Determination by Laser Induced Breakdown Spectroscopy (LIBS)Spectroscopy (LIBS)
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What is LIBS?What is LIBS?
Laser Induced Breakdown Spectroscopy (LIBS) is an emerging Laser Induced Breakdown Spectroscopy (LIBS) is an emerging analytical technique based on atomic and ionic emission of elemeanalytical technique based on atomic and ionic emission of elemental ntal sample constituents. sample constituents.
During the LIBS analytical process the sample is irradiated by aDuring the LIBS analytical process the sample is irradiated by ahighly energetic laser pulse and absorbs this energy. The high highly energetic laser pulse and absorbs this energy. The high temperature of ablated material generates a small plasma plume. temperature of ablated material generates a small plasma plume. As As result of the temperature, the ablated material breaks down intoresult of the temperature, the ablated material breaks down intoexcited ionic and atomic species.excited ionic and atomic species.
sample
Pulsed laser
Plasma
emission
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What is LIBS?What is LIBS?
During the plasma cooling, the excited species return to their gDuring the plasma cooling, the excited species return to their ground round state emitting electromagnetic radiation in characteristic wavelstate emitting electromagnetic radiation in characteristic wavelengths. engths.
In this sense, the analysis of sample emission spectra gives a qIn this sense, the analysis of sample emission spectra gives a qualitative ualitative view of sample elemental composition. view of sample elemental composition.
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Soil pelletcoin
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Laser 1064 nm
Plasma
Sample
Focuses lens
Fiber optics
spectrometer
Computer
Laser 1064 nm
Plasma
Sample
Focuses lens
Fiber optics
spectrometer
Computer
LIBS LIBS apparatusapparatus
Use Use ofof Artificial Neural Network (ANN)Artificial Neural Network (ANN)
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Embrapa systemsEmbrapa systemsBench Portable
Spectrometers manufactured by Ocean Optics model LIBS2500
spectral range: 188-980 nmResolution: 0.1 nm
Laser manufactured by Quantelmodel Big Sky Laser Ultra50
single-pulse energy 50 mJpulse duration 8nsDelay time: 3 µs
Spectrometers manufactured by StellarNet Incmodel LIBS2500
spectral range: 190-1000 nmResolution: 0.2 nm
Laser manufactured by Kigre Inc. model MK-367
single-pulse energy 20 mJpulse duration 4nsDelay time: 2 µs
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Typical soil emission Typical soil emission –– C regionC region
Da Silva, R, Milori, D. et al.. Spectrochimica Acta. Part B, Atomic Spectroscopy. , v.63, p.1221 - 1224, 2008.
190 192 194 196 198 200
0
50
100
150
200
250
300
350
Inte
nsid
ade
(u.a
.)
Comprimento de Onda (nm)
C
Al
wavelength (nm)
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LIBS + Artificial Neural Network for LIBS + Artificial Neural Network for Carbon analysisCarbon analysis
0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,10,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
1,1
C(%
) LIB
S/M
LP
C (%) TOC
R=0.93
LOD: 0,3%
C reference concentration
(%)
C predicted concentration
(%)
Absolute Error
0.51 0.43 (±0.04) -0.08
0.79 0.94 (±0.08) 0.15
0.62 0.78 (±0.15) 0.16
0.48 0.56 (±0.09) 0.08
0.65 0.76 (±0.10) 0.11
0.36 0.44 (±0.07) 0.08
0.45 0.51 (±0.07) 0.06
0.72 0.76 (±0.07) 0.04
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LIBS + ANN LIBS + ANN
0 1 2 3 4 5 6 7 8 90
50
100
150
200
250
Ba
(mg
kg-1)
Validation Samples
ICP OES LIBS
0 1 2 3 4 5 6 7 8 9 10
0
20
40
60
80
100
Co
(mg
kg-1)
Validation samples
ICP OES LIBS
0 1 2 3 4 5 6 7 8 9 100
50
100
150
200
250
Cu
(mg
kg-1)
Validation samples
ICP OES LIBS
0 1 2 3 4 5 6 7 8 9 100
200
400
600
800
1000
1200
1400
1600
1800
2000
Mn
(mg
kg-1)
Validation samples
ICP OES LIBS
Ba
MnCu
Co
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Sample preparationSample preparation
soil samples from experimental area
manual cleaning, and after the
samples are sieved
15 ton of
pressure1 pellet of
each sample(1 g)
Cost equipment ~ US$ 50.000,00
Cost / Analysis : US$ 0.50
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SoilsSoils & Humic & Humic SubstancesSubstancesLeaderLeader:: Dr. Ladislau Martin-Neto
ResearchResearch teamteam:: Débora MiloriSilvio CrestanaWilson T. L. da SilvaMarcelo L. SimõesCarlos VazLuiz A. ColnagoEdnaldo FerreiraAdolfo PosadasRoberto Quiroz
PosPos--docdoc:: Edilene C. FerreiraAline Segnini
StudentsStudentsCleber Hilário dos SantosBruno H. MartinsLilian F. de AlmeidaLívia FavorettoMariani MussiCamila CarvalhoAndré VenâncioMarcelo CardinalliMariana RussoMarina França-SilvaBruna D.L. PintoThais OahshiLilian F. de AlmeidaTatiana M. Ferrarezi
PartnershipsPartnerships::
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AcknowledgementsAcknowledgements
