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Linking biosensor responses to Cd, Cu and Zn partitioning in soils
J J C Dawson1, C D Campbell, W Towers
1School of Biological Sciences, University of Aberdeen, Cruickshank Building, St. Machar Drive, Aberdeen AB24 3UU, UK. j.j.dawson@abdn.ac.uk
Environmental Pollution (Barking, Essex : 1987)
|December 6, 2005
Summary
Bacterial biosensors effectively assessed heavy metal toxicity in soil pore waters, linking biological hazard assessments to physico-chemical parameters for critical metal loading determination.
Area of Science:
- Environmental Science
- Soil Science
- Ecotoxicology
Background:
- Soils naturally bind heavy metals based on physico-chemical properties.
- Assessing heavy metal bioavailability and toxicity in soils is crucial for environmental risk assessment, particularly concerning amendments like sewage sludge.
Purpose of the Study:
- To evaluate the responsiveness of bacterial biosensors to heavy metals (Cd, Cu, Zn) in soil pore waters.
- To correlate biosensor responses with standard soil-metal physico-chemical parameters, specifically the solid-solution partitioning coefficient (K(d)).
- To establish a link between biological hazard assessment and physico-chemical soil properties for determining critical metal loadings.
Main Methods:
- Bioassays were conducted using bacterial biosensors on pore waters extracted from 19 diverse soils.
- Soils were amended with cadmium (Cd), copper (Cu), and zinc (Zn) at concentrations relevant to the EU Sewage Sludge Directive.
- Heavy metal partitioning coefficients (K(d)) were calculated, and relationships between K(d), metal concentrations, and biosensor luminescence were analyzed using Gompertz functions.
Main Results:
- Bacterial biosensors showed significant responsiveness to Zn-amended soil pore waters and moderate responsiveness to Cu-amended pore waters.
- No significant toxicity was observed for Cd at environmentally relevant concentrations.
- The solid-solution heavy metal partitioning coefficient (K(d)) decreased with increasing Cu and Zn amendments, with Cu exhibiting the highest K(d) values.
- Gompertz functions effectively modeled the relationship between heavy metals and biosensor luminescence, linking K(d) values to biological responses.
Conclusions:
- Bacterial biosensors can serve as a valuable tool for assessing the biological hazard of heavy metals in soils.
- The study demonstrates a clear link between biosensor-based toxicity assessments and fundamental physico-chemical parameters (K(d)) of heavy metals in soils.
- This integrated approach aids in establishing critical metal loadings in soils, informing environmental regulations and risk management strategies.
