w t lopes da silva soil carbon analysis methods july 2010

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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

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www.cnpdia.embrapa.br

wilson@cnpdia.embrapa.br