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The effect of pH on the toxicity of zinc oxide nanoparticles to Folsomia candida in amended field soil
Author(s) -
WaalewijnKool Pauline L.,
Ortiz Maria Diez,
Lofts Stephen,
van Gestel Cornelis A.M.
Publication year - 2013
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.2302
Subject(s) - zinc , chemistry , soil water , sorption , toxicity , freundlich equation , nuclear chemistry , environmental chemistry , soil ph , inorganic chemistry , adsorption , biology , ecology , organic chemistry
The effect of soil pH on the toxicity of 30 nm ZnO to Folsomia candida was assessed in Dorset field soils with pH CaCl2 adjusted to 4.31, 5.71, and 6.39. To unravel the contribution of particle size and dissolved Zn, 200 nm ZnO and ZnCl 2 were tested. Zinc sorption increased with increasing pH, and Freundlich k f values ranged from 98.9 (L/kg) 1/ n to 333 (L/kg) 1/ n for 30 nm ZnO and from 64.3 (L/kg) 1/ n to 187 (L/kg) 1/ n for ZnCl 2 . No effect of particle size was found on sorption, and little difference was found in toxicity between 30 nm and 200 nm ZnO. The effect on reproduction decreased with increasing pH for all Zn forms, with 28‐d median effective concentrations (EC50s) of 553 mg Zn/kg, 1481 mg Zn/kg, and 3233 mg Zn/kg for 30 nm ZnO and 331 mg Zn/kg, 732 mg Zn/kg, and 1174 mg Zn/kg for ZnCl 2 at pH 4.31, 5.71, and 6.39, respectively. The EC50s based on porewater Zn concentrations increased with increasing pH for 30 nm ZnO from 4.77 mg Zn/L to 18.5 mg Zn/L, while for ZnCl 2 no consistent pH‐related trend in EC50s was found (21.0–63.3 mg Zn/L). Porewater calcium levels were 10 times higher in ZnCl 2 ‐spiked soils than in ZnO‐spiked soils. The authors' results suggest that the decreased toxicity of ZnCl 2 compared with 30 nm ZnO based on porewater concentrations was because of a protective effect of calcium and not a particle effect. Environ Toxicol Chem 2013;32:2349–2355. © 2013 SETAC