1. Cadmium mass and stable isotope budget of three Swiss agricultural sites
M. Imseng, M. Bigalke, M. Wiggenhauser, M. Müller, K. Murphy, K. Kreissig, M. Rehkämper, E. Frossard, A. Keller, W. Wilcke
NRP 69

2. Background – Cd Goldschmidt 2016-06-28 anthropogenic activities
highly toxic & carcinogenic
bone softening kidney dysfunction2
Natural dust deposition
Phosphate fertilizers
industry & mining
Crop availability1
0.1-1 mg kg-1
Food chain
weathering
f(total Cd, pH, organic matter)
Long biological half-life
63rd most abundant element in crustal rocks
Chronic exposure
1Smolders and Mertens (2010);
2Godt et al. (2006)

3. Establish Cd balance of three Swiss agricultural sites
Objectives
Goldschmidt 1)
Establish Cd balance of three Swiss agricultural sites 2)
Trace sources of Cd within the agricultural system 3)
Examine Cd redistribution processes within the agricultural system
Must be possibly adapted – depending on slides 10 and 11

4. Experimental sites Goldschmidt 2016-06-28 Oensingen Wiedlisbach
vertic Cambisol
Cambisol
Cambisol
Oensingen
Wiedlisbach
Nenzlingen
silt loam / high CEC /
pH 0-20 cm: 6.0
0.44 mg kg-1
sandy loam / low CEC /
pH 0-20 cm: 5.5
0.17 mg kg-1
silt loam / high CEC /
pH 0-20cm: 6.9
high background [Cd]
1.66 mg kg-1

5. Experimental design Input Output Reservoir Goldschmidt 2016-06-28
Cadmium mass and stable isotope budget
Output
Reservoir
Mineral
fertilizer
&
Manure
Bulk deposition
Crop harvest
Bulk soil Cd
0-50 cm
Experimental design
Plant
available Cd
Parent material
Leaching

6. Oensingen – Cd mass balance
Goldschmidt
Mineral
fertilizers
Wheat harvest
Bulk deposition
Input
Manure4
Output
Reservoir
Total Cd
x 23
Plant available Cadmium
0.05 M Ca(NO3)2
0-20 cm
pH 6.01
20-50 cm
pH 7.17
x 310
Rock weathering3
Leaching water
The «soil» boxes represent the Cd reservoirs (plant available Cd) for 0-20cm and 20-50cm . Inputs are shown in red and outputs in green. The value below «total Cd» refers to the total Cd content in the soil, which is 23 times and 310 times the plant available Cd concentrations.
The animation shows another hypothetical scenario:
-higher Cd concentrations in the applied fertilizers
-annual fertilizer application instead of application every 2nd year
-> statement: mineral fertilizer application is the sensitive parameter for the mass balance. If you apply more fertilizers or fertilizers with higher Cd concentrations, the balance can turn from a net loss to a net accumulation.
Net loss of 0.51 g ha-1 y-1
Net accumulation of 2.34 g ha-1 y-1
1 g ha-1 y-1
3Udluft and Quentin (1982); 4Keller et al. (2005)

7. Inputs – isotopic signatures
Goldschmidt
Inputs
Explanation
No industrial Cd evaporation process - organic component?
5,6,7,8
Oensingen
Wiedlisbach
Reflects animal feed – crops and pasture 9
Nenzlingen
Same signal as terrestrial rocks
7,10
Bulk deposition:
It was shown that Cd evaporation prefers light isotopes. Our bulk deposition is slightly enriched in heavy isotopes. We can exclude industrial Cd evaporation processes to be the dominant source of the bulk deposition Cd. The positive delta value could be explained by an organic component – Aboveground wheat and barley were shown to be positively fractionated.
Manure:
The positive delta value might reflect the animal feed (crops and pasture).
Phosphate fertilizers:
The isotopic signal is similar to the one of terrestrial rocks. There is apparently no isotopic fractionation during the phosphate fertilizer production.
Enriched in light isotopes
Enriched in heavy isotopes
5Wombacher et al. (2003); 6Cloquet et al. (2006); 7Shiel et al. (2010); 8Chrastný et al. (2015); 9Wiggenhauser et al. (submitted); 10Schmitt et al. (2009)

8. Harvest – isotopic signatures
Goldschmidt
Harvest
Explanation
Oensingen
Plant available δ114/110Cd > 0 9
Wiedlisbach
Nenzlingen
fractionation within the plants:
Root > straw > grain
light isotopes
heavy isotopes
Enriched in light isotopes
Enriched in heavy isotopes
Wheat and barley harvest: calculated isotopic signal consisting of grains and straw
Plant available Cd in soils is positively fractionated and plant induced Cd fractionation further enriches straw and grains in heavy isotopes.
9Wiggenhauser et al. (submitted)

9. Soil formation – isotopic signatures
Goldschmidt
Oensingen
Wiedlisbach
Nenzlingen
Explanation
Soil reservoir
Soil formation:
Heavy Cd is leached
Light Cd stays in the soil
11,12
Effect observable In NE: ∼80% of initial Cd is leached
-High background [Cd]
Inputs
OE + WI:
-Less leaching of initial Cd
-Lower background [Cd] -> higher influence of other inputs
Outputs
Soil formation process:
Parent material is chemically weathered and Cd is released. Different processes (Adsorption, complexation, precipitation) further influence the fate of Cd. On our sites, the soil water was found to be enriched in heavy istopes. Heavy isotopes are therefore supposed to be leached and lighter isotopes to stay in the soil.
This effect is well observable for NE: the soil Cd isotopic signal is lighter than the parent material signal. Tau-values indicated, that more than 80% of the initial Cd is lost in NE. Less of the initial Cd is lost in OE and WI, 50% at most.
Additionally we found very high background Cd concentrations in the parent material in NE, therefore other inputs like manure, bulk deposition and mineral fertilizer don’t affect the isotopic signal as much as in OE and WI, where the background Cd concentrations are lower (factor 3 lower in OE and factor 3.5 in WI).
Horner et al. (2011): During calcite precipitation: light isotopes are preferentially bound to the solid phase, ambient water is enriched in heavy isotopes.
Wasylenki et al. (2014): Cd isotope fractionation during adsorption to Mn oxyhydroxides -> preferntial adsorption of light isotopes.
Enriched in light isotopes
Enriched in heavy isotopes
11Horner et al. (2011); 12Wasylenki et al. (2014)

10. Oensingen – isotope budget
Goldschmidt
2015
-0.07 ‰ : 100 years
1 g ha-1 y-1
Bulk deposition
Mineral fertilizers
Manure
Wheat harvest
δ114/110Cd
0.18 ‰
0.00 ‰
0.38 ‰
0.51 ‰
0-50 cm
Soil reservoir ‰
x 40
Isotope budgets allow us to better understand the isotopic signal of the soil.
The isotopic budget of 2015 shows that the soil reservoir is getting lighter over time. The decisive parameter is the wheat harvest: High mass flow and very positive isotopic signal. The input of phosphate fertilizers also contribute to a shift towards more negative soil Cd isotopic values.
Expectation: Soil is getting lighter over time: We don’t observe this effect.
0.04 ‰ ‰
0.79 ‰
Rock weathering
New soil reservoir
Leaching water

11. Oensingen – isotope budget
Goldschmidt
Pre-agricultural-times
1 g ha-1 y-1
Bulk deposition
-0.07 ‰ : 10’000 years
δ114/110Cd
0.18 ‰
0-50 cm
Soil reservoir ‰
x 40
Isotope budget for pre-agricultural times: Much smaller variations. This might explain the small variations in the isotopic values of soil Cd.
Isotopic budgets are a useful tool to further investigate the isotopic signals of the soils
0.04 ‰ ‰
0.79 ‰
Rock weathering
New soil reservoir
Leaching water

12. Conclusions & outlook 1)
Goldschmidt 1)
Mineral phosphate fertilizers are decisive for the mass balances 2)
δ114/110Cd of manure reflects the cattle feed isotopic signal 3)
Leaching water is enriched in heavy isotopes
further investigation needed 4)
Plant harvest Cd is positively fractionated
Cd retention mechanism
There will be additional conlusions after the integration of slide 10 5)
Decisive parameter for the isotope budget varies over time and between different soils

13. Thank you for your attention!
Goldschmidt
Thank you for your attention!
Questions or insights?

14. References Goldschmidt 2016-06-28
(1) Six, L.; Smolders, E. Future trends in soil cadmium concentration under current cadmium fluxes to European agricultural soils. The Science of the total environment 2014, , 319–328. DOI: /j.scitotenv
(2) Godt, J.; Scheidig, F.; Grosse-Siestrup, C.; Esche, V.; Brandenburg, P.; Reich, A.; Groneberg, D. A. The toxicity of cadmium and resulting hazards for human health. J Occup Med Toxicol 2006, 1 (1), 22. DOI: /
(3) Udluft, P.; Quentin KM. Hydrogeochemical investigations with regard to the origin of heavy-metals in groundwater. ZeitsJournal for Water and Wastewater Research 1982, 15 (1), 6–11.
(4) Keller, A.; Rossier, N.; Desaules, A. Schwermetallbilanzen von Landwirtschaftsparzellen der nationalen Bodenbeobachtung: NABO - Nationales Bodenbeachtungsnetz der Schweiz; Schriftenreihe der FAL 54; FAL: Zürich, 2005.
(5) Wombacher, F.; Rehkämper, M.; Mezger, K.; Münker, C. Stable isotope compositions of cadmium in geological materials and meteorites determined by multiple-collector ICPMS. Geochimica et Cosmochimica Acta 2003, 67 (23), 4639–4654. DOI: /S (03)
(6) Cloquet, C.; Carignan, J.; Libourel, G.; Sterckeman, T.; Perdrix, E. Tracing source pollution in soils using cadmium and lead isotopes. Environmental science & technology 2006, 40 (8), 2525–2530.
(7) Shiel, A. E.; Weis, D.; Orians, K. J. Evaluation of zinc, cadmium and lead isotope fractionation during smelting and refining. The Science of the total environment 2010, 408 (11), 2357–2368. DOI: /j.scitotenv
(8) Chrastný, V.; Čadková, E.; Vaněk, A.; Teper, L.; Cabala, J.; Komárek, M. Cadmium isotope fractionation within the soil profile complicates source identification in relation to Pb–Zn mining and smelting processes. Chemical Geology 2015, 405, 1–9. DOI: /j.chemgeo
(9) Wiggenhauser M.; Bigalke M.; Imseng M.; Müller M.; Keller A.; Murphy K.; Kreissig K.; Rrehkämper M.; Wilcke W.; Frossard E. Cadmium isotope fractionation in soil-wheat systems. Environmental Science & Technology, submitted.
(10) Schmitt, A.-D.; Galer, S. J.; Abouchami, W. Mass-dependent cadmium isotopic variations in nature with emphasis on the marine environment. Earth and Planetary Science Letters 2009, 277 (1-2), 262–272. DOI: /j.epsl
(11) Horner, T. J.; Lee, R. B. Y.; Henderson, G. M.; Rickaby, R. E. M. Nonspecific uptake and homeostasis drive the oceanic cadmium cycle. Proceedings of the National Academy of Sciences 2013, 110 (7), 2500–2505. DOI: /pnas
(12) Wasylenki, L. E.; Swihart, J. W.; Romaniello, S. J. Cadmium isotope fractionation during adsorption to Mn oxyhydroxide at low and high ionic strength. Geochimica et Cosmochimica Acta 2014, 140, 212–226. DOI: /j.gca