Deposition and fate of trace metals in Finnish bogs and implications for the use of bogs as geological archives [Elektronische Ressource] / vorgelegt von Nicole Rausch

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Deposition and fate of trace metals in Finnish bogs and implications for the use of bogs as geological archives INAUGURAL – DISSERTATION Zur Erlangung der Doktorwürde der Naturwissenschaftlich-Mathematischen Gesamtfakultät der Ruprecht – Karls – Universität Heidelberg vorgelegt von Diplom-Geologin Nicole Rausch aus Karlsruhe Tag der mündlichen Prüfung: 14.07.2005 Gutachter: Prof. Dr. William Shotyk Institut für Umwelt-Geochemie Ruprechts-Karls-Universität Heidelberg Im Neuenheimer Feld 236 D-69120 Heidelberg PD Dr. Thomas Neumann Institut für Mineralogie und Geochemie Universität Karlsruhe (TH) Fritz-Haber-Weg 2 D-76131 Karlsruhe Summary Four sampling sites in Finland were selected for this study, each of them with known history of atmospheric metal deposition: Hietajärvi (HIJ), the low-background site; Outokumpu (OUT), near a former Cu-Ni mine; Harjavalta (HAR), near a Cu and Ni smelter and Alkkia (ALK), a site of experimental Cu/Ni application in 1962. The aim of this study is to determine the extent to which the atmospheric deposition of Cu, Ni, Co, Zn and Cd is preserved in peat profiles from ombrotrophic peatlands.

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Deposition and fate of trace metals
in Finnish bogs and
implications for the use of bogs as geological archives


INAUGURAL – DISSERTATION
Zur
Erlangung der Doktorwürde
der
Naturwissenschaftlich-Mathematischen Gesamtfakultät
der
Ruprecht – Karls – Universität
Heidelberg

















vorgelegt von

Diplom-Geologin Nicole Rausch
aus Karlsruhe

Tag der mündlichen Prüfung: 14.07.2005




































Gutachter: Prof. Dr. William Shotyk
Institut für Umwelt-Geochemie
Ruprechts-Karls-Universität Heidelberg
Im Neuenheimer Feld 236
D-69120 Heidelberg




PD Dr. Thomas Neumann
Institut für Mineralogie und Geochemie
Universität Karlsruhe (TH)
Fritz-Haber-Weg 2
D-76131 Karlsruhe
Summary

Four sampling sites in Finland were selected for this study, each of them with known history
of atmospheric metal deposition: Hietajärvi (HIJ), the low-background site; Outokumpu
(OUT), near a former Cu-Ni mine; Harjavalta (HAR), near a Cu and Ni smelter and Alkkia
(ALK), a site of experimental Cu/Ni application in 1962. The aim of this study is to determine
the extent to which the atmospheric deposition of Cu, Ni, Co, Zn and Cd is preserved in peat
profiles from ombrotrophic peatlands. The importance of post-depositional processes is
studied using two independent approaches: the comparison of metal accumulation rates in
peat profiles with monitoring data and emission records, and the comparison of metal
concentrations in porewater with those in bulk peat.

ICP-sector-field-MS was used to determine trace metal concentrations in both peat and
porewater samples. A new sampling device for the collection of porewater samples from
ombrotrophic bogs was developed. A complete sampling protocol was established following
strict quality control procedures. Blank values of the sampling devices were as follows (in µg
-1L ): Cd 0.001, Co 0.009, Cr 0.05, Cu 0.07, Mn 0.2, Mo 0.02, Ni 0.10, Pb 0.004, Sc
0.011, V 0.01, Zn 1. Additional contamination by atmospheric dust during the on-site
filtration was significant for Cr, Cu and Zn. The high content of humic substances in bog
porewaters causes filtration artefacts. A Hesslein-type in-situ porewater sampler was used to
collect porewater from HIJ and OUT via dialysis. Although this method would be less
affected by filtration artefacts, it was not possible to establish reliable concentration profiles at
these concentration levels with the exception of Co and Mn.

‘Background’ concentrations for metals in peat were calculated using deep layers at HIJ (in
-1µg g ): Cu 1.3 ± 0.2 (n=62), Co 0.25 ± 0.04 (n=71), Cd 0.08 ± 0.01 (n=23), and Zn 4 ± 2
(n=40). Similar concentrations were found in deep layers of all sites, while they were elevated
in upper layers. The metal distribution was independent of the input of mineral dust, the
degree of decomposition, and the distribution of S and Fe. The comparison of metal
accumulation rates with emission records showed that Cu and Co accurately reflected the
atmospheric deposition history of the mining site (OUT), while Ni, Zn and Cd were subjected
210to post-depositional processes. Although the uncertainties of the Pb age dates and the poor
time-resolution between adjacent samples made interpretations at HAR difficult, all metals
were found to be mobile. At HIJ and OUT, porewater concentrations were in a similar range
(< 8 nM Cu and Ni, < 1.4 nM Co, < 250 nM Zn). Although a limited release of Ni and Zn was
indicated at OUT, the generally low concentrations suggested that these metals were re-
distributed at an early stage of deposition. High Cd porewater concentrations confirmed post-
depositional processes at OUT, whereas Cu was immobile. The crucial point for the retention
of different metals at OUT might be the stability of ore-derived dust particles (e.g.
chalcopyrite, pyrrhotite) against oxidation in the aerated surface layer of the bog. Porewater
concentrations at HAR exceeded those at HIJ and OUT by a factor of 2 (Zn), 10 (Cd), 20 (Co)
and 100 (Cu and Ni), confirming post-depositional mobilization of all metals. This might be
explained by the deposition of smelter-derived metal oxide particles, which should readily
dissolve in the acid conditions of the HAR bog porewater (< pH 3.4).
Zusammenfassung

Vier Probenahmestellen mit bekannter atmosphärischer Spurenmetall-Deposition wurden
beprobt: Hietajärvi (HIJ) als Referenz für die Hintergrundbelastung; Outokumpu, in der Nähe
einer ehemaligen Cu-Ni-Mine; Harjavalta (HAR), nahe eines Cu und Ni Hüttenwerks und
Alkkia, wo 1962 in einer Feldstudie Metallsalze aufgetragen wurden. Ziel dieser Arbeit ist es
herauszufinden, in welchem Ausmaß die atmosphärische Cu, Ni, Co, Zn und Cd Deposition in
Torfprofilen aus Hochmooren aufgezeichnet wird. Dies wurde mittels zweier unabhängiger
Herangehensweisen studiert: Metall-Akkumulationsraten in Torfproben wurden mit der
tatsächlichen Deposition verglichen, und Metallkonzentrationen im Porenwasser wurden mit
Gesamtkonzentrationen verglichen.

Spurenmetall-Konzentrationen wurden mittels ICP-SF-MS bestimmt. Ein neues Gerät zur
Entnahme von Porenwasser-Proben in Hochmooren sowie ein vollständiges Probenahme-
-1Protokoll wurde entwickelt, mit folgenden Blindwerten: (in µg L ): Cd 0.001, Co 0.009,
Cr 0.05, Cu 0.07, Mn 0.2, Mo 0.02, Ni 0.10, Pb 0.004, Sc 0.011, V 0.01, Zn 1. Die
manuelle Filtration an der Probenahmestelle führte zu einer signifikanten Erhöhung der Cr,
Cu und Zn Blindwerte. Der hohe Gehalt an Huminstoffen in den Porenwässern führte zu
starken Filtrationsartefakten. In HIJ und OUT wurden zusätzlich Porenwasser-Proben mittels
Dialyse gewonnen (sog. „Hesslein peeper“). Diese Probenahme-Technik ist weniger anfällig
für Filtrationsartefakte, jedoch konnte damit keine zuverlässigen Konzentrationsprofile
gewonnen werden (Ausnahme: Co und Mn).

Folgende Hintergrund-Konzentrationen wurden in tiefen Torfschichten in HIJ bestimmt (in
-1µg g ): Cu 1.3 ± 0.2 (n=62), Co 0.25 ± 0.04 (n=71), Cd 0.08 ± 0.01 (n=23) und Zn 4 ± 2
(n=40). Ähnliche Konzentrationen wurden auch in den tieferen Torfschichten der anderen
Probenahme-Stellen gefunden, während obere Torflagen erhöhte Metall-Konzentrationen
aufwiesen. Die Metallkonzentrationen waren unabhängig vom Bodenstaub-Eintrag, vom
Zersetzungsgrad der Torfschichten und von den S und Fe Konzentrationen. Die Cu und Co
Akkumulationsraten spiegelten die atmosphärische Deposition in OUT hervorragend wider.
Nickel, Zn und Cd wurden dagegen nach der Ablagerung mobilisiert. Trotz Schwierigkeiten
bei der Altersbestimmung der Torfproben deuteten die Metall-Akkumulationsraten in HAR
auf eine Mobilisierung aller Metalle hin. Porenwasser-Konzentrationen in HIJ und OUT
waren niedrig (< 8 nM Cu and Ni, < 1.4 nM Co, < 250 nM Zn). Trotz Anzeichen einer
gewissen Freisetzung von Ni und Zn in OUT deuteten sie auf eine Umverteilung der Metalle
im Anfangsstadium hin. Hohe Cd bzw. niedrige Cu Konzentrationen im Porenwasser
bestätigten die Ergebnisse der ersten Herangehensweise. Die unterschiedliche Mobilität der
Metalle basiert vermutlich auf der unterschiedlichen Resistenz der abgelagerten Sulfiderze
gegen Oxidation an der Oberfläche des Moores. Porenwasser-Konzentrationen in HAR sind
stark gegenüber HIJ und OUT erhöht, vermutlich da dort leichtlösliche Metall-Oxide
abgelagert wurden.
List of original publications and the author’s contribution
This thesis is based on the following articles, which are included in the text as separate
chapters:

ANALYTICAL SECTION
Chapter 2
Rausch, N., L. Ukonmaanaho, T.M. Nieminen, M. Krachler, G. Le Roux, W. Shotyk. A syringe-type
sampler for obtaining porewaters from ombrotrophic bogs, and application to trace metal (µg L-1 to
sub-µg L-1) determinations. Limnology and Oceanography. Methods submitted (2005)

The paper was initiated and planned jointly by N. Rausch, L. Ukonmaanaho, T. Nieminen, M.
Krachler and W. Shotyk. The field work was performed by N. Rausch, T. Nieminen and L.
Ukonmaanaho. N. Rausch was responsible for the development of the new sampler, the establishment
of the sampling protocol, all analyses and the preparation of the article. Co-authors assisted in field
and laboratory work and the interpretation of the data.


Chapter 3
Krachler, M., N. Rausch, H. Feuerbacher, P. Klemens. 2005. A new HF-resistant tandem spray
chamber for improved determination of trace elements and Pb isotopes using inductively coupled
plasma - mass spectrometry. Spectrochimica Achta B (in print).

The paper was initiated and planned jointly by M. Krachler, N. Rausch, H. Feuerbacher and P.
Klemens. H. Feuerbacher and P. Klemens developed the new spray chamber. M. Krachler and N.
Rausch were responsible for the performance of the analyses. M. Krachler was responsible for the
interpretation of the data and the preparation of the article. Co-authors assisted in the interpretation of
the data.


PEAT BOGS AS ARCHIVES
Chapter 4
Ukonmaanaho, L., T.M. Nieminen, N. Rausch, W. Shotyk. 2004. Heavy metal and arsenic profiles in
ombrogenous peat cores from four differently loaded areas in Finland.Water, Air, and Soil Pollution
158: 277-294.

The paper was initiated and planned jointly by L. Ukonmaanaho, T. Nieminen, N. Rausch and W.
Shotyk. The field work was performed by Nieminen, Ukonmaanaho and Rausch. Ukonmaanaho and
Nieminen were responsible for the interpretation of the data and the preparation of the article. Rausch
was responsible for the sample preparations and assisted in the interpretation of the data.


Chapter 5
Rausch, N., T.M. Nieminen, L. Ukonmaanaho, G. Le Roux, M. Krachler, A.K. Cheburkin, G. Bonani,
W. Shotyk. 2005. Comparison of atmospheric deposition of copper, nickel, cobalt, zinc and cadmium
recorded by Finnish peat cores with monitoring data and emission records. Environmental Science and
Technology (accepted for publication).

The paper was initiated and planned jointly by N. Rausch, T. Nieminen, L. Ukonmaanaho and W.
Shotyk. The field work was performed by Nieminen, Ukonmaanaho and Rausch. Rausch was
responsible for the analytical part (except of age datings and XRF analyses), the interpretation of the
data and the preparation of the article. Co-authors provided historical and monitoring data, age datings
and XRF data and assisted in the interpretation of data.


Chapter 6
Rausch, N., T.M. Nieminen, L. Ukonmaanaho, M. Krachler, W. Shotyk. Porewater evidence of metal
(Cu, Ni, Co, Zn, Cd) mobilization in an acidic, ombrotrophic bog impacted by a smelter, Harjavalta,
Finland and comparison with reference sites. Environmental Science and Technology in review
(2005).

The paper was initiated and planned jointly by N. Rausch, T. Nieminen, L. Ukonmaanaho and W.
Shotyk. The field work was performed by Rausch, Nieminen and Ukonmaanaho. Rausch was
responsible for the analytical part, the interpretation of the data and the preparation of the article. Co-
authors assisted in the interpretation of data.


Appendix 1
Givelet, N., G. Le Roux, A. K. Cheburkin, B. Chen, J. Frank, M. E. Goodsite, H. Kempter, M.
Krachler, T. Noernberg, N. Rausch, S. Rheinberger, F. Roos-Barraclough, A. Sapkota, C. Scholz, W.
Shotyk. 2004. Suggested protocol for collecting, handling and preparing peat cores and peat samples
for physical, chemical mineralogical and isotopic analyses. Journal of Environmental Monitoring 6:
481-482.

The paper was initiated and planned jointly by N. Givelet, G. Le Roux and W. Shotyk. The protocol
paper was jointly developed during the period of this PhD by all co-authors. N. Rausch contributed to
the parts “Quantification of trace elements” (Cd and Ni analyses), “Age dating” (results from Finnish
cores) and “Quality control” (analyses of certified reference materials using different analytical
methods).


Appendix 3
Ukonmaanaho, L., T. Nieminen, N. Rausch, A. Cheburkin, G. Le Roux, W. Shotyk. 2005. Recent
organic matter accumulation related to some climatic factors in ombrotrophic peat bogs near heavy
metal emission sources in Finland. Global and Planetary Changes in review.

The paper was initiated and planned jointly by L. Ukonmaanaho, T. Nieminen, N. Rausch and W.
Shotyk. N. Rausch performed the field work jointly with T. Nieminen and L. Ukonmaanaho. N.
Rausch prepared all samples and performed the density measurements and carbon analyses. N. Rausch
also assisted in the interpretation of the data. Co-authors were responsible for the interpretation of the
210data, XRF analyses, Pb age dating and the preparation of the article.