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The availability of trace metals in the rhizosphere of contaminated soils from the Sudbury area. (Processes)

Objectives being Investigated
The long-term objective is to establish the contribution of rhizospheric processes to the cycling of trace metals in forest soils. The specific objectives are to contrasts the fractionation of metals for different levels of soil contamination and under distinct forest canopies. It is hypothesized that in disturbed environments, such as contaminated soils, the magnitude of the perturbation is the main factor controlling the extent and the direction of the rhizosphere effect.

Study/Sampling Design
The study sites are located along a transect of historic metal deposition from anthropogenic sources in the Sudbury area. Three sites corresponding to the permanent plots already established by MITE-RN researchers (Hale & Hendershot) were used in the fall of 2001 to collect rhizosphere and bulk materials under white birch (Betula alleghaniensis). Sampling will also be conducted in 2002 along the same gradient but under Abies balsamea and Picea mariana canopies. This design allows the acquisition of soil samples under varied vegetation covers for each of the three contamination level. The sites are otherwise uniform with respect to soil type, landscape position and microclimatic conditions.

Location of Field Site(s)
The three sites are located at 2, 8 and 30 km west of the Sudbury, Ontario smelter:
Site 1: 46° 35.8' N; 80° 49.9' W
Site 2: 46° 35.9' N; 80° 37.4' W
Site 3: 46° 35.2' N; 80° 15.6' W

Biota Studied

Species
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Metals, etc. Quantified
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Biological Endpoint(s)
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Physical Material(s) Studied

Medium/Media
Soil (Podzolic order). In each soil profile, samples are collected in the A or B horizon and the rhizosphere material is separated into an inner and an outer fraction by shaking. The bulk soil is also collected.

Metals, etc. Quantified
The trace metals Cd, Cu, Ni, Pb and Zn in water, BaCl2, Na-pyrophosphate, NH4-oxalate and HF extracts from the rhizosphere and the bulk soil of each soil sample. The free Cu ion activity is also measured in the water extract. Al and Fe analyzed in the oxalate extracts. Total metals by Synchrotron X-ray Fluorescence Micro-Analysis on selected thin sections of aggregates around roots. Mineralogical (XRD) and textural analyses (hydrometer) are performed on bulk soils. The pH in water and the organic C content is measured for rhizosphere and bulk soil materials.

Bibliographic References on-file with Secretariat: No

Data Available: No

Data Archived with MITHE-SN: No

Collaborators