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Copper speciation and microbial activity in long-term contaminated soils
A Dumestre1, S Sauvé, M McBride
1Department of Soil, Crop and Atmospheric Sciences, Cornell University, Ithaca, New York 14853, USA.
Archives of Environmental Contamination and Toxicology
|January 15, 1999
Summary
Long-term copper contamination impacts soil microbes and carbon mineralization. Soil solution free Cu2+ activity (pCu2+) best predicts copper toxicity, while microbial respiration lag period (LP) serves as a reliable bioindicator.
Area of Science:
- Environmental Science
- Soil Science
- Microbiology
Background:
- Current soil quality guidelines often fail to differentiate metal forms, treating hazardous and non-hazardous metal fractions equally.
- Understanding the chemical speciation of metals is crucial for assessing their true environmental impact and toxicity.
- Long-term effects of metal contamination on soil microbial communities and functions require further investigation.
Purpose of the Study:
- To investigate the long-term effects of copper contamination on soil microorganisms and carbon mineralization.
- To correlate copper's chemical speciation in soil with its observed toxicity to microbial communities.
- To evaluate the suitability of different microbial indicators for assessing copper toxicity in contaminated soils.
Main Methods:
- Analysis of carbon mineralization processes and microbial community structure (fungi, eubacteria, actinomycetes) in 20 agricultural soils with over 50 years of copper contamination.
- Measurement of microbial respiration lag period (LP) and maximum mineralization rate (MMR).
- Correlation analysis of LP and MMR with total copper concentration, soil pH, soil organic matter (SOM), and soil solution free Cu2+ activity (pCu2+).
Main Results:
- Copper contamination significantly affected carbon mineralization and microbial community structure even after 50 years.
- Microbial respiration lag period (LP) increased with copper contamination and was best predicted by soil solution free Cu2+ activity (pCu2+), integrating soil physicochemical variability.
- Maximum mineralization rate (MMR) was sensitive to soil organic matter (SOM) and less reliable as a biomonitor for copper contamination.
Conclusions:
- Soil physicochemical properties significantly influence heavy metal toxicity and the effectiveness of toxicological measurements.
- Measuring pCu2+ is essential for characterizing soil copper contamination levels.
- The lag period (LP) of microbial respiration is a valuable bioindicator for assessing copper's biological effects and overall soil quality.