Técnicas Avançadas no Estudo de Fósforo
Asst. Prof. Hudson W.P. Carvalho
Group of Applied X-ray Spectroscopy
Universidade de São PauloCentro de Energia Nuclear na AgriculturaLaboratório de Instrumentação Nuclear
Overview
The P problem from a chemist perspective
X-ray spectroscopy
X-rays spectroscopy & phosphorus @ USP
Brazilian exports
Where the US$ come from?
36% of all Brazilian exports in 2017 was Agri
Phosphorus peak: is it real?
https://www.producer.com/2019/09/phosphorus-grains-double-edged-sword/
http://www.rainharvest.co.za/2010/07/peak-phosphorus-what-does-this-mean/
Phosphorus management
Like in energy management,P management must be integrate
P inputs – P harvested
Are we creating P stocks/reserves?
Every year we bring a littleof Morocco to Brazil.
Are we using the rightphosphate fertilizers?
P Dynamics
Can we use X-rays to unlock P dynamics?
Synchrotron
2 mm0.000
131.9
263.8
395.6
527.5
659.4
791.3
923.1
1055
P
http://www-ext.impmc.upmc.fr/~blanchard/Crimin.html
2D chemical imaging
3D chemical imaging
Structure
US$ 13
US$ 367
Can we play with P prices?
Can we master soil physical-chemistry?
Université de Paris1898
Kaiser-Wilhelm-Gesellschaft
zur Förderung der Wissenschaften
1939
Imperial College1928
University of Cincinnati 1954
X-ray related discoveries/inventions
Biomolecule structures: DNA, Ribosome, Proteins Minerals Catalysts mechanisms Medical devices
X-ray fluorescencespectroscopy
X-ray absorptionspectroscopy
&
DVTEC – Laboratório de Instrumentação Nuclear
Limits of detection in XRF
2Introduction to
X-ray Fluorescence Spectroscopy
DVTEC – Laboratório de Instrumentação Nuclear
Lab Equipments for XRF
Micro-XRF
Handheld XRF
Total Reflection XRF
EDXRF$ 50 K $ 60 K
$ 180 K
$ 90 K
Introduction toX-ray Fluorescence Spectroscopy 3
DVTEC – Laboratório de Instrumentação Nuclear
What does happen after absorption?
Introduction toX-ray Fluorescence Spectroscopy 14
DVTEC – Laboratório de Instrumentação Nuclear
Principles of XAS- spectral regions
X-ray Absorption Spectroscopy for the Direct Analysis of Solids
E 0
1shn
Modified from Dr. Valerie Briois
E 0
1shn
very lowE c
3d
E 0
1shn
E c low
E 0
1shn
E c High
Ab
sorb
ance
5900 6100 6300 6500 6700
E (eV)
XANES EXAFS
Pre-edge edge
Cr XAS spectrum
The electron fateafter ejection
≠ theories for ≠ regions
33
Examples ofX-ray fluorescence
spectroscopy
cX-ray fluorescence & P uptake
Microprobe X-rayfluorescence spectrometer
c
Why does it precipitate?
X-ray fluorescence & P uptake
Time (h)0 4
c
Sugar cane leaves
In vivo & in situ P quantitative analysisNovember 2019Thais Soares, doctoral cand.Prof. P. PavinatoESALQ-USP
Treatments:FNR STPFNR+ Torta STP+Torta
Examples of X-rayabsorption spectroscopy
cXANES and P figerprint
L-edge K-edge
What are we doing atCENA & ESALQ
USP
In partnership with Prof. Paulo S. Pavinato, ESALQ-USP
P gradients in the rhizosphereof soybean
cX-ray fluorescence & P uptake
Total P concentration
• Determination by standard addition methodSample Increment (mg/kg) Intensities
cps/uA
P0 (Original) 0 0.0121
P5 200 0.0147
P4 400 0.0166
P3 600 0.0222
P2 800 0.0208
P1 1000 0.0219
y = 1E-05x + 0.0125
R² = 0.9909
0
0.01
0.02
0.03
0 500 1000 1500
Standard addition
[P] = 1280 mg kg-1
• Wet chemical fractionation indicated only 1.6% isreadily available to the plants.
• 3.8% is labile, i.e. plants can access at the expense ofroot exudates.
• Nearly 24% is strongly adsorbed to the soil.• 70.6% is not any more accessible.
Element soil
Adjusted R-
Square
Slope
Al 0.95 1.08±0.02
Si 0.93 1.05±0.02
Ca 0.59 0.31±0.02
Fe 0.81 0.75±0.02
Rh L 0.84 0.61±0.02
Soil layer disposedon the top a XRF cuvette
Scatter plotsCredits: Dr. Matheus Barreto
P1
P2
P3
P4
P5
Exploring points
XRF is not restricted to phosphorus
125 µm125 µm
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.60
50
100
150
200
250
P in
ten
sity (
ne
t in
ten
sity)
Distance (mm)
Instrumental LOD
Phosphorus
In situ Linescans
The least disturbance
0.0 0.2 0.4 0.6 0.8 1.0 1.20
20
40
60
80
100
120
140
160
P inte
nsity (
net in
tensity)
Distance (mm)
Instrumental LOD
Phosphorus
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
0
20
40
60
80
100
120
Inte
nsity (
ne
t in
ten
sity)
Distance (mm)
K
Rh
P
100
200
300
400
500
600
-20
0
20
40
60
80
100
120
140
160
180
P depletion layer?
0.0 0.2 0.4 0.6 0.8 1.0 1.20
20
40
60
80
100
120
140
160
P inte
nsity (
net in
tensity)
Distance (mm)
Instrumental LOD
Phosphorus
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
Distance (mm)
P / Rh intensity
P intensity
P n
orm
aliz
ed b
y R
h
-20
0
20
40
60
80
100
120
140
160
180
P n
et net in
tensity
P depletion layer?
Gradients close to hairs?
Perhaps we need higher lateral resolution to probe the hairneighbourhood
Tracing P movement in soil
LNLS beamtimein November 2018
cP imaging & chemical speciation
MAP granule
cLNLS setup
Mn chemical speciation
Time= 15:35-16:2720.09.18
Time= 19:18-22:0020.09.18
Time= 22:01-00:3020.09.18
Time= 00:56-04:1021.09.18
0.5 mm-5.5 mm
0 mm
2.5 mm
Granule 1
We traced P diffusionfrom granule to root
Time= 10:00-13:0221.09.18
Time= 13:04-16:1021.09.18
Time= 16:11-19:0921.09.18
Time= 20:43-23:4621.09.18
5 mm-4.5 mm
3 mm
5 mm
Granule 2
We traced P diffusionfrom granule to root
cIn vivo P uptake & Speciation
2140 2150 2160 2170 21800.00E+000
1.00E+013
2.00E+013
3.00E+013
4.00E+013
5.00E+013
XR
F P
-K
(E)
(cps)
Energy (eV)
M_Xanes_BOX3_Fert_raiz_t0
M_Xanes_BOX3_Fert_raiz_t3
2140 2150 2160 2170 21800
1
2
3
4
5
Norm
. P
-K
(E)
Energy (eV)
M_Xanes_BOX3_Fert_raiz_t0
M_Xanes_BOX3_Fert_raiz_t3
Non-Normalized
NormalizedIncreasing P content
P concentration increased in roots the influx P is chemically diferentefrom pristine P
Innovation in targeting phosphorusinputs to crops: uptake and mobility of foliar phosphate
In partnership withProf. Paulo S. Pavinato, ESALQ-USPProf. Paul Whiters, U. Bangor (UK)
cP foliar uptake by wheat Marcos Gomes, 3rd year doctoral candidate
Dr. Wilfrand Herrera, ESALQ
c
Healthy plants absorb faster
X-ray fluorescence & P uptake
