6
Concluding discussion
45
7
Vanadium and risk assessments
47
8
Sammanfattning (Swedish summary)
49
References
51
Acknowledgements
59
7
List of Publications
This thesis is based on the work contained in the following papers, referred to
by Roman numerals in the text:
I
Larsson, M.A., Persson, I., Sjöstedt, C. & Gustafsson, J.P. (2014). Vanadate
complexation to ferrihydrite: X-ray absorption spectroscopy and CD-
MUSIC modelling. Manuscript.
II
Larsson, M.A., Baken, S., Gustafsson J.P., Hadialhejazi, G. & Smolders, E.
(2013). Vanadium bioavailability and toxicity to
soil microorganisms and
plants. Environmental Toxicology and Chemistry 32 (10), 2266-2273.
III
Baken, S., Larsson M.A., Gustafsson, J.P., Cubadda, F. & Smolders E.
(2012). Ageing of vanadium in soils and consequences for bioavailability.
European Journal of Soil Science 63 (6), 839-847.
IV
Larsson, M.A., Baken, S., Smolders E., Cubadda F. & Gustafsson, J.P.
(2014). Vanadium bioavailability in soils amended with blast furnace slag.
Submitted manuscript.
V
Larsson, M.A., D’Amato, M., Cubadda, F., Raggi, A., Öborn, I., Berggren
Kleja, D. & Gustafsson, J.P. (2014). Long-term fate and transformations of
vanadium added by converter lime to a forest soil. Submitted manuscript.
Papers II and III are reproduced with the permission of the publishers.
8
The contribution of Maja A. Larsson to the papers included in this thesis was
as follows:
I
Planned the study together with the fourth author. Performed the
laboratory work and XAS analysis with some assistance. EXAFS and
wavelet analyses were performed by the second and third author,
respectively. Performed the modelling and writing with assistance from
the co-authors.
II
Planned the study together with the second, third and fifth author.
Performed the experimental work together with the second author.
Performed data analyses and writing with assistance from the co-authors.
III
Planned the study together with the first, third and fifth author. Performed
the experimental work together with the first author and assisted in data
analyses and writing.
IV
Planned the study together with the third and fourth author. Performed
experimental work together with the second author. Performed data
analyses and writing with assistance from the co-authors.
V
Planned the study together with the seventh author. Performed soil
sampling, laboratory work and XANES data analysis.
Performed writing
with assistance from the co-authors.
9
Abbreviations
EC10
Effective concentration at 10% inhibition
EC50
Effective concentration at 50% inhibition
EXAFS
Extended X-Ray Absorption Fine Structure
Fh
Ferrihydrite
HAO
Aluminium (hydr)oxide
LCF
Linear combination fitting
OM
Organic matter
PNR
Potential Nitrification Rate
V
Vanadium
XANES
X-Ray Absorption Near Edge Structure
XAS
X-Ray Absorption Spectroscopy
11
1 Introduction
Vanadium, V, is a transition metal and is among the 20 most abundant
elements in the Earth’s crust, in the same concentration range as lead and
copper. Its main application in human society is within the steel industry, in
alloys. The anthropogenic input to the environment is dominated by burning of
fossil fuels. The steel industry generates by-products that due to their alkalinity
and physical properties are suitable as soil amendments, road fill materials and
cement. In Sweden, these materials are naturally high in vanadium. Since the
human body always contains traces of vanadium, there are ethical and practical
issues with investigating the impact of vanadium deficiency in humans. Thus
vanadium essentiality to humans has still not been confirmed (Anke et al.,
2005). However, excessive vanadium concentrations may be carcinogenic
(Beyersmann & Hartwig, 2008). Historically, there are cases of accidental
releases of vanadium to the environment. One of the most recent was a spillage
of the bauxite residue “red mud” in Ajka, Hungary, in 2010. In addition to
alkalinity and sodium concentrations, the red mud also contained 900 mg kg
-1
vanadium (Ruyters
et al., 2011). In the 1980s, basic slag containing 3%
vanadium was inappropriately applied as a soil amendment in Lillpite in
northern Sweden. The amendment resulted in contamination of hay, which
caused the death of 23 cattle due to acute vanadium toxicity (Frank et al.,
1996).
Knowledge of vanadium behaviour in soils is poor compared with that of
heavy metals such as copper, lead and zinc, and many countries lack threshold
values for vanadium in soils and waters. The median value of total vanadium
concentration in European topsoils is 60 mg kg
-1
, but some soils may have up
to 500 mg V kg
-1
. In comparison, most toxicity-based values for unacceptable
risks range from 90 to 500 mg V kg
-1
for those member states of the European
Union that have established limit values for vanadium in soils (Carlon, 2007).