Spatial distribution of metallic trace elements in soils contaminated by atmospheric fallouts. Case study: Sclaigneaux (Belgium)

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Spatial distribution of metallic trace elements in

soils contaminated by atmospheric fallouts

Case study: Sclaigneaux (Belgium)

Bari (Italy), 3rd_{July 2012}

LIÉNARD AMANDINE PHD STUDENT

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Aims

1. Spatial distribution of metallic trace elements

(MTE) at the landscape scale in the topsoil, in

the subsoil and in sediments

2. Impact of land uses, soil types, wind

directions and distance from contaminants

source on the MTE content

3. Risk assessment for agricultural soil

utilisations

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Study area:localization

Belgium

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Study area: characteristics

Meuse valley Situation of old chimney

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Study area: characteristics

- Different soil types

- Land uses (crops, grasslands and forests) - Old factories

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Topsoil study

Sampling Strategy - Map projections

Sampling points are distributed between 3 distinct soil types, 3 land uses and 4 wind directions (36 combinations)

1. Main soil types 2. Land use 3. Wind directions

Loamy soil with good drainage Loamy soil with imperfect drainage Loamy stony soil with silexite and gravels

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Methodology

• 250 topsoil samples were collected according to this stratified design

• All samples were prepared for analyses :

-Pseudo-total contents in inorganic elements -pH

-Total Organic Carbon -N

• Statistical analyses : -Anova (AV3)

-Ancova (AV3) with distance as covariate -PCA

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Distance from source:

The main factor influencing MTE content in topsoil

- Content in each MTE decreases with distance - P-value < 0.001 and R2 _{> 0.5} y = 30877x-1,248 R² = 0,5281 0 10 20 30 40 50 60 70 80 90 0 500 1000 1500 2000 2500 3000 To tal cad m iu m c o n te n t (p p m )

Source of contamination distance (m)

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Direction of dominant winds :

A second factor which influences MTE content in topsoil

0 1 2 3 4 5 6 7

South West North East

Cadmium content (ppm)

- Typical wind direction in Wallonia is South-West toward North-East

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Soil types :

A third factor which influences the MTE content in topsoil

0 1 2 3 4 5 6 7 A ve rag e c ad m iu m c o n te n t in to p soil ( ppm ) Cadmium 0 50 100 150 200 250 300 350 A ve rag e le ad c o n te n t in t o p soil ( ppm ) Lead 0 100 200 300 400 500 600 700 A ve rag e z in c c o n te n t in t o p soil ( ppm ) Zinc

- Loamy stony soils with silexite and gravels contain more MTE than loamy soils

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Land use :

A last factor which influences the MTE content in topsoil

0 1 2 3 4 5 6 7 8 9

Crop Grassland Forest

A ve rag e c ad m iu m c o n te n t in t o p soil Cadmium 0 100 200 300 400 500 600

A ve rag e lead c o n te n t in t o p soil Lead 0 100 200 300 400 500 600 700 800 900

A ve rag e z in c c o n te n t in t o p soil Zinc

- Forest content in MTE is always higher (2X) than the other land uses - Likely due to higher content in organic matter, lower pH,…

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Confirmation by PCA analysis

0.5 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 0.75 0.50 0.25 0.00 -0.25 -0.50 First Component Se co nd C om po ne nt South East West North Forest Grassland Crop

Loamy soil - imperfect drainage

Loamy soil - good drainage

Loamy pebbles rich soil

Distance Cu

Zn Pb Cd

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Topsoils

Risk assessment study

In a 1km radius around the source, there is 80% chance for each contaminant to be above the allowed regional intervention value

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Sediments

Contaminated topsoil

Loss of soil and

MTE associated

?

 Comparison of topsoil and sediment samples taken very close from each other (max 3m)

Sediments sample Topsoil sample

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Comparison of speciation elements

from topsoil and sediments

Available fraction Fraction related to carbonate Fraction related to amorphous oxides Fraction related to crystallized oxides Fraction related to the organic matter Residual fraction

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Contaminated topsoil

?

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MTE leaching?

0 10 20 30 40 50 60 70 80 90 0 5 10 D e p th o f p ro fi le (c m )

Cadmium total contents (ppm)

Loamy soil Sandy soil 0 10 20 30 40 50 60 70 80 90 0 1000 2000 3000 D e p th o f p ro fi le (c m )

Lead total contents (ppm)

0 10 20 30 40 50 60 70 80 90 0 200 400 600 800 D e p th o f p ro fi le (c m )

Zinc total contents (ppm)

- Atmospheric dusts are at the origin of the contamination - MTE evolution is different according to the kind of soil

Spatial distribution of metallic trace elements in soils contaminated by atmospheric fallouts. Case study: Sclaigneaux (Belgium)