environmental arsenic speciation - umweltgeochemie · environmental arsenic speciation definitely...
TRANSCRIPT
![Page 1: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/1.jpg)
Environmental Arsenic Speciationdefinitely more than just arsenite and arsenate!
Grand Prismatic Hot Spring, Yellowstone NP
![Page 2: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/2.jpg)
Arsenic the classical poison
Homemade elderberry wine
laced with Arsenic StrychnineArsenic, Strychnine and just a pinch of
CyanideCyanide
Joseph Kesselring, 1939
![Page 3: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/3.jpg)
18401840
1836 M h t t1836 Marsh test
![Page 4: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/4.jpg)
Principle of Marsh´s TestpDetermination of total As by hydride generation
As2O3 + 6Zn + 6H2SO4 → 2AsH3 + 6Zn(SO4)2 + 3H2O
+3 -30 +2+3 -30 +2
As
![Page 5: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/5.jpg)
Arsenic speciesse c spec es
Arsenate As(V)
Arsenate As(V)
Arsenite As(III)
Arsenite As(III)
![Page 6: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/6.jpg)
1970s Species-selective Hydride GenerationSeparating As(III) and As(V)
H3AsIIIO30 / H3AsVO4
0 + NaBH4 AsH3
8090
100H3AsO3H3AsO4As(III)“
0607080 H3AsO4
pK 2.2 pK 9.2
„As(III)
304050
p p
As(III)“
0102030 „As(III)
+ „As(V)“
00 1 2 3 4 5 6 7 8 9 10 11 12
![Page 7: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/7.jpg)
Ion chromatography for speciation of arsenite and arsenate+ detection e g by atomic absorption spectroscopy
1.E+05
+ detection e.g. by atomic absorption spectroscopy
8.E+04
6.E+04
ity [c
ps]
HA O 2
4.E+04
al in
tens HAsO4
2-
arsenate
2.E+04
sign
a
arseniteH3AsO3
0
0.E+000 2 4 6 8 10 12 14 16 18 20 220 2 4 6 8 10 12 14 16 18 20 22
time [minutes]
![Page 8: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/8.jpg)
Modeling arsenite and arsenate distribution
ArsenitepK1, pK2, pK3 (H3AsO3)
t t d+ protonated species H4AsO3
+
A tArsenatepK1, pK2, pK3 (H3AsO4)
link arsenite - arsenate
![Page 9: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/9.jpg)
Traditional Arsenic Speciation
Arsenate07
06
Arsenate
05
04
03
01
03
Arsenite02
01
Gibbon Geyser Basin
![Page 10: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/10.jpg)
Sulfidic environment affects arsenic speciation!
Arsenicup to 5 4 mg/L
Sulfide0 1 5 /L up to 5.4 mg/L0.1-5 mg/L
H2S
Grotto Geyser
![Page 11: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/11.jpg)
Chromatographic separation revealed As species with retention times that did not match those of any commercial standards
1.E+05
times that did not match those of any commercial standards
?
8.E+04?
?
6.E+04
ity [c
ps]
4.E+04
al in
tens arsenate ?
2.E+04
sign
a
arsenite?
0.E+000 2 4 6 8 10 12 14 16 18 20 220 2 4 6 8 10 12 14 16 18 20 22
time [minutes]
![Page 12: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/12.jpg)
Requires a more selective detector:I d ti l l d l t tInductively coupled plasma mass spectrometry
ELAN DRC II ICP-MS, Perkin Elmer
Samplepintroductionca.1 ml/min
aerosolaerosolH2AsO4
-
Plasma 6000-8000°C
atomAs, H, O
ionAs+, H+, O+
![Page 13: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/13.jpg)
Detection of unknown As species
1.E+05sulfate S:As S:As
8.E+04
Arsenic AsO+Sulfur SO+
sulfate S:As0.95 ± 0.1n = 17
S:As2.99 ± 0.22
n = 26
6.E+04y [c
ps]
4 E+04
6.E 04
inte
nsity
arsenatesulfide
S:As1.92 ± 0.14
n = 21 S:As
2 E+04
4.E+04
sign
al
thiosulfateca.4
2.E+04 arsenite
0.E+000 2 4 6 8 10 12 14 16 18 20 22
time [minutes]
![Page 14: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/14.jpg)
Thioarsenates or Thioarsenites?
Thioarsenites
OH SH SH SHOH OH SH SH
As AsAs As
OH OHOH SH
Mono~ Di~ Tri~ Tetra~
OH
OH – As = O
OH
OH – As = O
OH
SH – As = O
SH
SH – As = O
SH
SH – As = SOH As O
SH
OH As O
OH
SH As O
SH
SH As O
SH
SH As S
SH
Thioarsenates retention time match with synthesized standards
![Page 15: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/15.jpg)
Electrospray Ionization MSElectrospray Ionization MSNo prior chromatographic separation!
No atomization of compoundp
• „Soft ionization“, rather transfer from solution to gasg• Solvent evaporation• Formation of desolvated aerosol
H A O ions by Coulombic fission (repellent forces by charged molecules)
H2AsO4-
molecules)
![Page 16: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/16.jpg)
Thioarsenates or Thioarsenites? Identical molecular masses of thioarsenites and thioarsenates on low-resolution
Thioarsenites
mass spectrometry is a problem for electrospray ionization mass spectrometry
OH SH SH SHOH OH SH SH
As AsAs As
OH OHOH SH
Mono~ Di~ Tri~ Tetra~141 157 173
OH
OH – As = O
OH
OH – As = O
OH
SH – As = O
SH
SH – As = O
SH
SH – As = SOH As O
SH
OH As O
OH
SH As O
SH
SH As O
SH
SH As S
SH141 157 173
Thioarsenates retention time match with synthesized standardsm/z: 2 * O (2*16) S (32)
![Page 17: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/17.jpg)
ESI-MS proofs for thioarsenates not thioarsenites
1. ES Q-TRAP MS molecular massesless deviations when assuming thioarsenate m/z ratios
Measured m/z
Thio-arsenate
expected m/z for thio-
rel. dev.
Thio-arsenite
expected m/z for thio-
rel. dev. [ppm]arsenate [ppm] arsenite [ppm]
140.914 H2AsO4- 140.9169 -20.6 H2AsO2S- 140.8991 +105.7
156 891 H AsO S- 156 8941 19 8 H AsOS - 156 8763 +93 7156.891 H2AsO3S 156.8941 -19.8 H2AsOS2 156.8763 +93.7
172.868 H2AsO2S2- 172.8712 -18.5 H2AsS3
- 172.8535 +83.9
188 848 H2AsOS3- 188 8484 -0 53188.848 H2AsOS3 188.8484 0.53
204.825 H2AsS4- 204.8255 -4.88
Wallschläger & Stadey Anal. Chem. 2007, 79, 3873-3880
![Page 18: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/18.jpg)
ESI-MS proofs for thioarsenates not thioarsenites
1. ES Q-TRAP MS molecular masses
OH
less deviations when assuming thioarsenate m/z ratios
OH
SH – As = O2. ES-MS-MS fractionation patterns
(m/z 173 eliminated H2O SH SH
As
SHmust be H2AsO2S2-
H2AsS3- can not eliminate H2O!)
SH
![Page 19: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/19.jpg)
trithio-ESI-MS proofs for thioarsenates not thioarsenites
arsenate
1. ES Q-TRAP MS molecular masses
dithio-arsenate
arsenate
less deviations when assuming thioarsenate m/z ratios
2. ES-MS-MS fractionation patterns(m/z 173 eliminated H2O must be H AsO S2-
monothio-arsenate
must be H2AsO2SH2AsS3
- can not eliminate H2O!)
3 Analysis of IC fractions by ES MStetratharsena
3. Analysis of IC fractions by ES-MS known As:S ratios from IC and molecular mass information from ES-MS
800 1000 1time [s]
S:As 1:1Monothioarsenite (m/z = 141)
Monothioarsenate (m/z = 157)
![Page 20: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/20.jpg)
Thioarsenates predominate arsenic speciationat the geothermal sources
dot size = sum of thioarsenates [%]
![Page 21: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/21.jpg)
Methylated (thio)arsenatesaccounted for all remaining missing species
CH3
CH3 – As = Oaccounted for all remaining missing species CH3 As O
SHSlightly different eluent:0- 3 min 2.5 mM3- 5 min 2.5 20 mM 1.0x104 dimethyl-
arsenitedimethyl-arsenate arsenate
ps]3 5 min 2.5 20 mM
5-10 min 20 mM10-20 min 20 100 mM20 24 i 2 5 M 3
monothio-arsenate
monomethyl-arsenate
monothio-arsenatey
AsO
+ [cp
20-24 min 2.5 mM
No suppressor
1.0x103
monomethyl- monothio- arsenate
arsenate
dithio-arsenatena
l int
ensi
ty
Additional As species: 13-20% DMA
1.0x102
arsenate
sign
13-20% DMA 1% MMA 5% DMMTA 200 400 600 800 1000 120
1.0x101
0.5% MMMTA time [s]
![Page 22: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/22.jpg)
Why were thioarsenates notWhy were thioarsenates not detected in previous studies?p
![Page 23: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/23.jpg)
Preservation of arsenic speciation by acidification90
10012.0
14.0
speciation by acidification
607080
cove
ry [%
]
8.0
10.0
H
304050
arse
nic
rec
4.0
6.0
pH
010
20
0.0
2.0
80
90
100
%]
12.0
14.0
90100
12.0
14.0
50
60
70
80
reco
very
[%
8.0
10.0
pH
607080
ecov
ery
[%]
8.0
10.0H
20
30
40
50ar
seni
c r
4.0
6.0
p
20304050
arse
nic
re
4.0
6.0
p
0
10
20
0.0
2.0
01020
0.0
2.0
![Page 24: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/24.jpg)
Preservation of arsenic speciation by acidificationYellowstone: Trithioarsenate pH >6speciation by acidification
not suitable in sulfidic waters!
Monothioarsenate at all pH conditions
not suitable in sulfidic waters!
flash-freezing
1.2
1.4Monothioarsenate
Dithioarsenate
Trithioarsenate
0.8
1
[mg/
L]
Trithioarsenate
Tetrathioarsenate
0.4
0.6
arse
nic
0
0.2
02 3 4 5 6 7 8 9 10
pH
![Page 25: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/25.jpg)
Analysis of arsenic by hydride generationnot suitable for arsenic speciation in sulfidic waters!
H3AsO30 / H3AsO4
0 + NaBH4 AsH3T t l d ith KI / bi
not suitable for arsenic speciation in sulfidic waters!
8090
100H3AsO3H3AsO4
„As(III)“
Totals: prered. with KI /ascorbicacid in 3.5 M HCl
40506070
pK 2.2 pK 9.2
Speciation: non-std. procedure
• different buffers
10203040 p p
„As(III)“
+ „As(V)“
• final pH 4 to 7
• batch vs. flow injection
Totals: thioarsenates arsenate arsenite
00 1 2 3 4 5 6 7 8 9 10 11 12
(diff. pH of sample / reductant prior to mixing)
Totals: thioarsenates arsenate, arsenite correct (if samples were not acidified for preservation and 1% KI is used as pre-reducing agent; not L-cysteine)
Species: „As(III)“: Arsenite, Di-, Tri-, and Tetrathioarsenate„As(V)“: Arsenate, Monothioarsenate
![Page 26: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/26.jpg)
Traditional Arsenic Speciation
ArsenateImplications of existence
f hi
0706
Arsenate
of thioarsenates…05
04
03
01
03
Arsenite02
01
Gibbon Geyser Basin
![Page 27: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/27.jpg)
Implications for speciation transformations and redox processesp
1.6 1.6
1 2
1.4
1 2
1.4measured byhydride generation
measured by AEC-ICP-MS
1.0
1.2
L]
1.0
1.2
L]
0 6
0.8
seni
c [m
g/L
0 6
0.8
seni
c [m
g/L
0.4
0.6ars
0.4
0.6ars
0 0
0.2
0 0
0.2
0.00 3 6 9 12 15 18 21 24 27 30 33 36
distance from source [m]
0.00 3 6 9 12 15 18 21 24 27 30 33 36
distance from source [m]
![Page 28: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/28.jpg)
„Oxidation“ of thioarsenate to arsenite??1190
1070950
830
720
600
480
360
240
120
0
Thioarsenate / Arsenite ArsenateXX
0
-120
-240
-360
Arsenite + S0 donor Thioarsenate
X
XX
X-480
-600
-720
830
Arsenite + (Sulfide) / S0 donor ThioarsenateXX
-830
-950
intermediate S species determine As speciation
![Page 29: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/29.jpg)
Influence of S-oxidizing microorganisms on arsenic redox transformations…?
• transformation rates are 40-500 times faster (k =
1/min, t1/2 = 0.6 min) than in abiotic control experiments
in the laboratory (k = 0 004/min t1/2 = 170 min)in the laboratory (k 0.004/min, t1/2 170 min)
• arsenate production coincides with the temperature-
dependent occurrence of organisms closely related to
Thermocrinis ruber a known sulfur-oxidizerThermocrinis ruber, a known sulfur oxidizer
![Page 30: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/30.jpg)
Implications for toxicity
1.6 1.6
measured by measured by AEC-ICP-MSLab toxicity tests exposing Vibrio fischeri to thioarsenate standards:
1 2
1.4
1 2
1.4measured by
hydride generation
yto thioarsenate standards:
Exposure time 15 min:
1.0
1.2
L]
1.0
1.2
L]
p
trithioarsenate = arsenite > di >> mono
??
0 6
0.8
seni
c [m
g/L
0 6
0.8
seni
c [m
g/L
Exposure time 60 min:
trithioarsenate > arsenite
??
0.4
0.6ars
0.4
0.6arstrithioarsenate > arsenite
lack of adaptation for thioarsenates?
0 0
0.2
0 0
0.2in the presence of both arsenite and trithioarsenate sig lower toxicity0.0
0 3 6 9 12 15 18 21 24 27 30 33 36distance from source [m]
0.00 3 6 9 12 15 18 21 24 27 30 33 36
distance from source [m]
trithioarsenate sig. lower toxicity
antagonism trithioarsenate - arsenite?
![Page 31: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/31.jpg)
Grenoble, FranceGrenoble, FranceESRF = European Synchrotron Radiation Facility
So what about the thioarsenites …?Synchrothron radiation main advantages: radiation with a large y g gspectrum (IR, VIS, UV, X-Ray), high intensity, sharp focus
844 m
![Page 32: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/32.jpg)
X-ray absorption spectroscopy XAS
monochromator(monochromatic X-rays)
synchrotron radiation source
I0
(high energetic, precise radiation)
incoming beam
sample
absorption
fluorescenceI1
absorption
fluorescence
I2reference (e.g. Au0, As0)
![Page 33: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/33.jpg)
Resulting data: XAS spectra2.5
XANES (E0 ± 50 eV) X ray Absorption Near Edge Spectroscopy
2.0
XANES (E0 ± 50 eV) X-ray Absorption Near-Edge Spectroscopy• oxidation state• local site symmetry and orbital occupancy
1.5
bsor
ptio
n µ absorption edge E0
As 11867 eV
1.0
mal
ized
ab
EXAFS
0.5
nor Extended X-ray Absorption Fine-Structure
50 – 1000 eV above E0, local coordination• bond distances R
0.011650 11850 12050 12250 12450 12650
• coordination number CN • type and number of neighbors
11650 11850 12050 12250 12450 12650
Energy [eV]
![Page 34: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/34.jpg)
Interpretation of coordination number AsS from EXAFS vs. edge position from XANES
As(V)As(III) • First spectra of synthesized thioarsenate standards
upon acidification Thioarsenites?
4
Tetrathioarsenate thioarsenate standards
• First detection of thioarsenates and
2
3
elle
d C
N
Dithioarsenate
As2S3
A S
thioarsenites in the same solution
1
2
mod
e
Monothioarsenate
DithioarsenateAs4S4
011867 11868 11869 11870 11871 11872
Na-ArsenateNa-Arsenite
E0 [eV]
![Page 35: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/35.jpg)
Can the occurrence of thioarsenates and thioarsenites be predicted by thermodynamic models?
![Page 36: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/36.jpg)
Can the occurrence of thioarsenates and thioarsenites be predicted by thermodynamic models?
pH
be predicted by thermodynamic models?
TetrathioarsenateH 9 5 d 12 3
pH 6.3 TetrathioarsenateT ithi it
pH 5.8 Trithio-it
pH 2.3 Trithio-it + A S
1 00E-02
1.00E-012 3 4 5 6 7 8 9 10 11 12
pH pH 9.5 and 12.3Trithioarsenitearsenitearsenite + As2S3
1.00E-03
1.00E 02
H3AsS3As2S3 precipitation
1.00E-04
ion
[mol
/L] H2AsS3-
AsS4-3
AsO4-3
1.00E-06
1.00E-05
conc
entr
at
As tot
1.00E-07
1.00E-08
![Page 37: Environmental Arsenic Speciation - Umweltgeochemie · Environmental Arsenic Speciation definitely more than just arsenite and arsenate! Grand Prismatic Hot Spring, Yellowstone NP](https://reader034.vdocuments.us/reader034/viewer/2022042322/5f0c737d7e708231d435775f/html5/thumbnails/37.jpg)
Projekte• Charakterisierung Thioarsenate/Thioarsenite mit IC-ICP-MS, XAS, RAMAN Elke
DFG Emmy Noether Förderung: Hydrogeochemische Speziierung von As, Au, Cu in Fe-S-Systemen unter Berücksichtigung abiotischer und mikrobiell katalysierter Wechselwirkungen
• Conny: Mikrobiell katalysierte Speziierung in As-Au-S Geothermalsystemen (Yellowstone, Neuseeland) Elke & April (DAAD RISE Praktikantin) As-S + Fe Ulli DA B d t i t diä S S i fü A R d dl tl th l Ulli: DA Bedeutung intermediärer S-Spezies für As-Redoxumwandlungen entlang geothermaler Drainagekanäle in Yellowstone NP (Photometrie vs. ionensensitive Elektrode)
• Abiotische Thioarsen-Speziierung im Fe(II)/Fe(III) System (Probenstabilisierung, Bildung von Fe-As-S Komplexen, Thioarsenat-Sorption/Remobilisierung auf Fe-Hydroxiden und Fe-Sulfiden)p p g y )
• Abiotische Reaktionen von Au- und Cu-Thioarsen-Spezies (Chile, etc.)
DFG Forschergruppe etrap• Identifikation von Polysulfiden und ihre Bedeutung als intermediäre Schwefel-Spezies für
Elektronentransferprozesse in anoxischen Aquiferen Sasan: Derivatisierung Polysulfide, Methoden-Setup RP-IC-ICP-MS Polysulfide als Elektronenshuttle bei indirekter FeOOH Reduktion durch Sulfurospirillum deleyianum Polysulfide als Elektronenshuttle bei indirekter FeOOH-Reduktion durch Sulfurospirillum deleyianum
Postdocs• Sasan: Organo-As-S-Verbindungen, As in Lebensmitteln / Toxikologie…?g g g• Nathaniel Wilson: Thioantimonate, Humboldt-Postdoc-Stipendium beantragt
MSc OS3 Toxizitätstests mit Vibrio fischeri für Thioantimonate