title: Bacterial community structure and activity in different Cd-treated forest soils.
abstract: In this study we compared indicators of Cd bioavailability (water extracts, Lakanen extracts, free ions) and ecotoxicity in forest soils with contrasting physico-chemical characteristics. Soil samples were treated with CdCl(2) solutions (0, 0.1, 1, 10 and 100 mM) and incubated for 30 days. Microbial activity indexes (acid phosphatase, beta-glucosidase, basal respiration) and changes in bacterial community structure using terminal restriction fragment length polymorphism (T-RFLP) fingerprinting were investigated. The Cd concentrations measured ranged from 1% to 37% of the total additions in water extracts, to higher levels in Lakanen extracts. Effects of Cd were observed at bioavailable concentrations exceeding United Nations/European Economic Commission UN/ECE guidelines for total Cd in the soil solution. Basal respiration was the most affected index, while enzymatic activities showed variable responses to the Cd treatments. We also noticed that soils with pH higher than 6.7 and clay content higher than 50% showed inhibition of basal respiration but no marked shift in bacterial community structure. Soils with lower pH (pH <5.8) with less clay content (<50%) showed in addition strong changes in the bacterial community structure. Our results provide evidence for the importance of relating the effects of Cd on the soil communities to soil properties and to bioavailability.
authors.affiliation: Soil Ecology, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland.
authors.forename: Anna
authors.initials: A
authors.lastname: Lazzaro
authors.forename: Martin
authors.initials: M
authors.lastname: Hartmann
authors.forename: Peter
authors.initials: P
authors.lastname: Blaser
authors.forename: Franco
authors.initials: F
authors.lastname: Widmer
authors.forename: Rainer
authors.initials: R
authors.lastname: Schulin
authors.forename: Beat
authors.initials: B
authors.lastname: Frey
mesh_terms: D000135:Acid Phosphatase / Q000032:analysis; D000538:Aluminum Silicates / Q000032:analysis; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000145:classification* / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000032:analysis; D044822:Biodiversity; D019256:Cadmium Chloride / Q000032:analysis / Q000494:pharmacology*; D000077215:Clay; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology; D014197:Trees / Q000382:microbiology*; D001617:beta-Glucosidase / Q000032:analysis
chemical_list: D000538:Aluminum Silicates; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012987:Soil; D000135:Acid Phosphatase; D001617:beta-Glucosidase; D019256:Cadmium Chloride; D000077215:Clay