m etal l evels and m icrobial e ffects in f orest s oils at the a vesta and o xelÖsund s teel w...

METAL LEVELS AND MICROBIAL EFFECTS IN FOREST

SOILS AT THE AVESTA AND OXELÖSUND STEEL WORKS

Staffan Åkerblom , Lage Bringmark www.ma.slu.seMail: ([email protected]) Tel: +46 18 67 31 26

METAL LEVELS AND MICROBIAL EFFECTS IN FOREST SOILS AT THE AVESTA AND OXELÖSUND STEEL WORKS

(rapport JK 95041 2006-03-24)

Lage Bringmark and Staffan ÅkerblomDepartment of Environmental Assessment

Swedish University of Agricultural Sciences, Uppsala

in cooperation with Jernkontoret (the study was performed in 2002 and 2003)

mailto:[email protected]



Objectives

•Study the load and exposure from metals in organic forest top soils (mor layer) around 2 major steel works in central Sweden

•Use total metal concentrations in soil and porewater (tension lysimeter in vitro) to study the exposure of metals to soil microbial ecosystems

•Study to what degree alkaline deposition affects metal exposure and possibly microbial function

•Study metal effects on forest soil microbial function by the use of small scale spatial patterns




Studysites


Avesta•Since 17th century (Cu and Zn) •Stainless steel 1920- •Moved 1949 to present location•Smelting of scrapmetals

Production:

•Steelwork expanded production in the 1950s•Rawmaterial iron ores and coal

Oxelösund

Major metals:

•Iron(!)•molybdenum•Vanadium•(chromium and zink)

•molybdenum•chromium•nickel•(iron, copper, vanadium and cadmium)




Field study(sampling for small scale spatial patterns)


A: Metals intercepted by trees are heterogeneously deposited on the forest floor

B: Samples are taken at the nodes of regular grid systems measuring 50*50m2




Studysites


Avesta Oxelösund

Nyköping

1: AGA 2: Kyrkbyn 3: Grönsinka (ref) 1:Fence 2: Brannäs 3: Lid (ref)




Podsol


•Mor layer: Brown-blackish, high organic content (70-95%) and low pH (3.7-4.0). Deadplant and animal material in different stages of decomposition. High metal retentioncapacity. Differentiated in upper Of-layer, lower Oh-layer.

•E-horizon: Grey colour, leached mineral soil, low organic content, pH 3.9-4.2.

•B-horizon: Reddish-brown colour, mineral soil with precipitated aluminium-ironorganiccomplexes, pH 4.3-4.7. Metal accumulation.

•C-horizon: Light-brown colour, unaffected subsoil, pH 5-6

MOR LAYER




Metal load / exposure (1)


AGA (600 m) Kyrkbyn (3000 m) Grönsinka (ref)

Ratio* Mean Ratio* Mean Mean

Mo 113 277 13 31 2.4

Cr 98 733 11 83 7.4

Ni 45 560 10 129 12

Fence (1000 m) Brannäs (2000 m) Lid (ref)

Ratio* Mean Ratio* Mean Mean

Fe 23 39903(!) 13 30321(!) 1717

Mo 9.6 7.6 9.4 7.4 0.8

V 9.4 142 8.9 135 15

Oxelösund

Avesta

*Ratio to reference=mean at site

mean at reference

To

tal m

eta

l co

nce

ntr

ati

on

mg

* k

g-1



Pore water extraction


1 2 3

4

1. Soil material from mor layer2. Collection vessel3. Suction vessel (-0.3 bar)4. Ceramic lysimeter probe (1 μm pore size)5. PVC tubing

5



pH and metal solubility


Avesta Oxelösund

Kd=Total metal

concentration

Dissolved metal concentration

Alkaline deposition!



Metal load / exposure (2)


AGA (600 m) Kyrkbyn (3000 m) Grönsinka (ref)

Ratio* Mean (N=4) Ratio* Mean (N=4) Mean (N=4)

Mo >1000 847 10 7.9 0.8

Cr 5.5 19 5.1 18 3.5

Ni 8.7 50 5.5 32 5.7

Fence (1000 m) Brannäs (2000 m) Lid (ref)

Ratio* Mean Ratio* Mean (N=4)

Mean (N=2)

Fe

Not available

Not available

Mo 39 11.5 0.04

V Not available

Oxelösund

Avesta

*Ratio to reference=mean at site

mean at reference

Dis

solv

ed m

eta

l co

nce

ntr

ati

on

μg

* L

-1



Microbial response to metal load (and exposure…?) 1


AVESTA

10.9550.598Ni

Ni10.612Cr

Cr1Mo

Mo

10.9550.598Ni

Ni10.612Cr

Cr1Mo

Mo

However….Strong covariation among metals!(Pearson correlation coefficient)




Microbial response to metal load (and exposure…?) 2


10.9040.771V

V10.921Mo

Mo1Fe

Fe

10.6700.438V

V10.817Mo

Mo1Fe

Fe

However….Strong covariation among metals!(Pearson correlation coefficient)

OXELÖSUND



Conclusion (1)


AVESTA:•Very high levels of metal concentrations•Only small fractions of cationic metal species (Cr and Ni) were dissolved•Mo was found in extremely high concentrations due to MoO4

- -formation in alkaline condition•Very probable toxic effects on microbial respiration

OXELÖSUND:•High levels of metal concentrations•Small fractions of metal species were dissolved•No, or minor, disturbance on microbial respiration was found



Conclusion (2)


•Results on microbial toxicity were verified with experimentally derived toxic endpoints for individual metal species

•Metal distribution in the soil profile was also studied

Further reading:•Metal levels and microbial effects in forest soils at the Avesta and Oxelösund steel works. Lage Bringmark and

Staffan Åkerblom. Swedish University of Agricultural Sciences. Jernkontoret (rapport JK 95041 2006-03-24)

•Anthropogenic heavy metals in organic forest soils – Distribution, microbial risk assessment and Hg mobility. Staffan Åkerblom. PhD-thesis no. 2006:67. Faculty of Natural Resources and Agricultural Sciences. Swedish University of Agricultural Sciences. (ISSN 1652-6880; ISBN 91-576-7116-8)

m etal l evels and m icrobial e ffects in f orest s oils at the a vesta and o xelÖsund s teel w...

Documents

f orest s oils

o xelsund s teel w orks

lage bringmark

icrobial e ffects

metal exposure

upper o f layer

mor layer slide

s rawmaterial iron ores