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Microfungi and microbial activity along a heavy metal gradient
A Nordgren1, E Bååth, B Söderström
1Department of Microbial Ecology, University of Lund, Helgonavägen 5, S-223 62 Lund, Sweden.
Applied and Environmental Microbiology
|June 1, 1983
Summary
Heavy metal pollution from a brass mill significantly reduced soil fungal biomass and respiration by 75%. While fungal species composition drastically changed, total fungal counts remained stable, indicating a shift in microbial community structure due to copper and zinc contamination.
Area of Science:
- Environmental microbiology
- Soil science
- Ecotoxicology
Background:
- Industrial activities, such as brass milling, release heavy metals into the environment.
- Heavy metal contamination can significantly impact soil microbial communities and ecosystem functions.
- Understanding the effects of specific pollutants like copper (Cu) and zinc (Zn) on soil fungi is crucial for ecological risk assessment.
Purpose of the Study:
- To investigate the impact of a steep copper and zinc gradient on soil fungal biomass, species composition, and respiration rate.
- To determine the threshold concentration of copper affecting fungal communities.
- To assess the relative influence of heavy metals versus soil properties on soil fungi.
Main Methods:
- Studied conifer mor soil along a copper and zinc gradient (up to 20,000 µg/g) near a brass mill.
- Measured soil fungal biomass, microfungal species composition (using CFU and isolation frequency), and soil respiration rate.
- Employed partial least squares (PLS) analysis to differentiate the effects of heavy metals from soil moisture and organic matter content.
Main Results:
- Fungal biomass and soil respiration decreased by approximately 75% along the metal gradient.
- Significant decreases in fungal biomass and respiration were evident above 1,000 µg Cu/g soil.
- Fungal species composition was drastically altered, with a decline in Penicillium and Oidiodendron, and an increase in Geomyces, Paecilomyces, and sterile forms near the mill.
- Mortierella abundance peaked at moderate pollution levels but decreased at the highest pollution levels.
Conclusions:
- Heavy metal pollution is the primary driver of changes in soil fungal communities, overriding the effects of soil moisture and organic matter.
- Soil fungal biomass and respiration are sensitive indicators of heavy metal pollution, with significant impacts observed at elevated copper concentrations.
- The shift in fungal species composition suggests adaptation or selection under high metal stress, with implications for soil ecosystem functioning.