Atmospheric deposition and isotope biogeochemistry of zinc in ombrotrophic peat
Weiss, Dominik J. ; Rausch, Nicole ; Mason, Thomas F.D. ; Coles, Barry J. ; Wilkinson, Jamie J. ; Ukonmaanaho, Liisa ; Arnold, Tim LU
and Nieminen, Tiina M.
(2007)
In Geochimica et Cosmochimica Acta
71(14).
p.3498-3517
- Abstract
Zinc isotope ratios were measured in the top sections of dated ombrotrophic peat cores in Finland to investigate their potential as proxies for atmospheric sources and to constrain post depositional processes affecting the geochemical record. The peat deposits were located in Hietajärvi, a background site well away from any point pollution source and representing 'background' conditions, in Outokumpu, next to a mining site, and in Harjavalta, next to a smelter. Measured total concentrations, calculated excess concentrations and mass balance considerations suggest that zinc is subjected to important biogeochemical cycling within the peat. Significant isotopic variability was found in all three peat bogs, with heavier zinc in the deeper... (More)
Zinc isotope ratios were measured in the top sections of dated ombrotrophic peat cores in Finland to investigate their potential as proxies for atmospheric sources and to constrain post depositional processes affecting the geochemical record. The peat deposits were located in Hietajärvi, a background site well away from any point pollution source and representing 'background' conditions, in Outokumpu, next to a mining site, and in Harjavalta, next to a smelter. Measured total concentrations, calculated excess concentrations and mass balance considerations suggest that zinc is subjected to important biogeochemical cycling within the peat. Significant isotopic variability was found in all three peat bogs, with heavier zinc in the deeper and lighter zinc in the upper sections. Isotope ratios and concentrations correlated in the two peats located next to dominant point sources, i.e. the smelting and mining site, suggesting that zinc isotopes trace pollution sources. Concentration and isotope peaks were offset from the period of mining and smelting activity, supporting migration of zinc down the profile. The δ66ZnJMC (where δ66Zn = [(66Zn/64Zn)sample/(66 Zn/64Zn)JMC-standard - 1] × 103) of the top section sample at the remote Hietajärvi site was 0.9‰ and we suggest this represents the regional background isotope signature of atmospheric zinc. The deeper sections of the peat cores show isotopically heavier zinc than any potential atmospheric source, indicating that post depositional processes affected the isotopic records. The large variations encountered (up to 1.05‰ for δ66Zn) and Rayleigh modelling imply that multiple fractionation of zinc during diagenetic alterations occurs and nutrient recycling alone cannot explain the fractionation pattern. We propose that zinc isotopes are amenable to identify different atmospheric zinc sources, including zinc derived from anthropogenic activities such as mining and smelting, but multiple biogeochemical processes seriously affect the record and they need to be evaluated and assessed carefully if zinc isotopes are used in terrestrial paleorecords.
(Less)
- author
- Weiss, Dominik J.
; Rausch, Nicole
; Mason, Thomas F.D.
; Coles, Barry J.
; Wilkinson, Jamie J.
; Ukonmaanaho, Liisa
; Arnold, Tim
LU
and Nieminen, Tiina M.
- publishing date
- 2007-07-15
- type
- Contribution to journal
- publication status
- published
- in
- Geochimica et Cosmochimica Acta
- volume
- 71
- issue
- 14
- pages
- 20 pages
- publisher
- Elsevier
- external identifiers
-
- scopus:34347356608
- ISSN
- 0016-7037
- DOI
- 10.1016/j.gca.2007.04.026
- language
- English
- LU publication?
- no
- id
- 7347b91a-55dd-4729-bf8b-0f02d81196ea
- date added to LUP
- 2024-10-24 18:40:39
- date last changed
- 2025-04-11 10:33:22
@article{7347b91a-55dd-4729-bf8b-0f02d81196ea,
abstract = {{<p>Zinc isotope ratios were measured in the top sections of dated ombrotrophic peat cores in Finland to investigate their potential as proxies for atmospheric sources and to constrain post depositional processes affecting the geochemical record. The peat deposits were located in Hietajärvi, a background site well away from any point pollution source and representing 'background' conditions, in Outokumpu, next to a mining site, and in Harjavalta, next to a smelter. Measured total concentrations, calculated excess concentrations and mass balance considerations suggest that zinc is subjected to important biogeochemical cycling within the peat. Significant isotopic variability was found in all three peat bogs, with heavier zinc in the deeper and lighter zinc in the upper sections. Isotope ratios and concentrations correlated in the two peats located next to dominant point sources, i.e. the smelting and mining site, suggesting that zinc isotopes trace pollution sources. Concentration and isotope peaks were offset from the period of mining and smelting activity, supporting migration of zinc down the profile. The δ<sup>66</sup>Zn<sub>JMC</sub> (where δ<sup>66</sup>Zn = [(<sup>66</sup>Zn/<sup>64</sup>Zn)<sub>sample</sub>/(<sup>66</sup> Zn/<sup>64</sup>Zn)<sub>JMC-standard</sub> - 1] × 10<sup>3</sup>) of the top section sample at the remote Hietajärvi site was 0.9‰ and we suggest this represents the regional background isotope signature of atmospheric zinc. The deeper sections of the peat cores show isotopically heavier zinc than any potential atmospheric source, indicating that post depositional processes affected the isotopic records. The large variations encountered (up to 1.05‰ for δ<sup>66</sup>Zn) and Rayleigh modelling imply that multiple fractionation of zinc during diagenetic alterations occurs and nutrient recycling alone cannot explain the fractionation pattern. We propose that zinc isotopes are amenable to identify different atmospheric zinc sources, including zinc derived from anthropogenic activities such as mining and smelting, but multiple biogeochemical processes seriously affect the record and they need to be evaluated and assessed carefully if zinc isotopes are used in terrestrial paleorecords.</p>}},
author = {{Weiss, Dominik J. and Rausch, Nicole and Mason, Thomas F.D. and Coles, Barry J. and Wilkinson, Jamie J. and Ukonmaanaho, Liisa and Arnold, Tim and Nieminen, Tiina M.}},
issn = {{0016-7037}},
language = {{eng}},
month = {{07}},
number = {{14}},
pages = {{3498--3517}},
publisher = {{Elsevier}},
series = {{Geochimica et Cosmochimica Acta}},
title = {{Atmospheric deposition and isotope biogeochemistry of zinc in ombrotrophic peat}},
url = {{http://dx.doi.org/10.1016/j.gca.2007.04.026}},
doi = {{10.1016/j.gca.2007.04.026}},
volume = {{71}},
year = {{2007}},
}