Determination of Acute Zn Toxicity in Pore Water from Soils Previously Treated with Sewage Sludge Using Bioluminescence Assays

• Published in: Environmental science & technology 1999-06, Vol.33 (11), p.1880-1885
• Main Authors: Chaudri, Amar M, Knight, Bruce P, Barbosa-Jefferson, Vera L, Preston, Sara, Paton, Graeme I, Killham, Ken, Coad, Nicholas, Nicholson, Fiona A, Chambers, Brian J, McGrath, Steve P
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Applied sciences; Biological and medical sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Biosensors; Copper; Ecotoxicology, biological effects of pollution; Escherichia coli; Exact sciences and technology; Fluorescence; Fundamental and applied biological sciences. Psychology; Groundwater; Microorganisms; Pollution; Pseudomonas fluorescens; Sewage disposal; Sewage sludge; soil amendments; Soil and sediments pollution; Soils; Terrestrial environment, soil, air; Toxicity; Zinc
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es980753+

The effects of increasing concentrations of Zn and Cu in soil pore water from soils of a long-term sewage sludge field experiment on microbial bioluminescence were investigated. Concentrations of total soluble Zn, free Zn2+, and soluble Cu increased sharply in soil pore water with increasing total soil metal concentrations above 140 mg of Zn kg-1 or 100 mg of Cu kg-1. Two luminescence bioassays were tested, based on two bacteria (Escherichia coli and Pseudomonas fluorescens) with the lux genes encoding bacterial luminescence inserted into them. The bioluminescence response of the two microorganisms declined as total soil Zn, soil pore water soluble Zn, and soil pore water free Zn2+ concentrations increased. The EC25 values for E. coli and P. fluorescens were 1.3 ± 0.2 and 4.3 ± 0.5 mg L-1 on a free Zn2+ basis, respectively. The EC50 values were 2.5 ± 0.2 and 9.6 ± 0.9 mg of free Zn2+ L-1, respectively. Copper had no significant effect on bioluminescence in the two assays, even at the largest soil pore water concentration of about 620 μg L-1, corresponding to a total Cu concentration in bulk soil of about 350 mg kg-1. Thus, the decline in bioluminescence of the two assays was ascribed to increasing soil pore water free Zn2+ and not soluble Cu.