Copper accumulation and fitness of Folsomia candida Willem in a copper contaminated sandy soil as affected by pH and soil moisture

Abstract

Collembolans of the species Folsomia candida Willem were exposed to copper at different concentrations (11–122 mg kg −1) and pH levels (pHCaCl 2 between 3.8 and 5.4) in soil collected from a field site. Total (HNO 3 extractable) soil copper was determined, and the copper fraction available to the collembolans was estimated by extracting copper from the soil by different methods (extraction with 0.01 M CaCl 2, extraction with artificially composed rainwater, and centrifugation to obtain the pore-water of the soil). Results were compared with the copper content of the collembolans and the effects of copper on three fitness parameters of the collembolans, viz. adult survival, reproduction and growth. For one soil treatment, the influence of soil moisture content on the fitness of the collembolans and on the toxicity of copper was studied by applying four levels of soil moisture (30, 50, 79 and 90% of the field capacity of the soil). Desorption of copper from the soil was best described by a two-species Freundlich equation that includes the influence of pH. No effects of copper were found on F. candida at the levels tested. Total soil copper was the best predictor of copper concentrations in the adult collembolans, and the inclusion of pH as a second factor improved the predictive value. Soil moisture had a large effect on fitness parameters of and copper accumulation by the collembolans, but there was no correlation between accumulation and fitness.