Competition effects for copper between soil, soil solution, and yeast in a bioassay for Folsomia candida Willem

Abstract

We investigated the accumulation of copper (Cu) by the springtail Folsomia candida Willem, if exposed to Cu-contaminated sandy soil with yeast as a food source. Commonly, the dissolved and the easily desorbed Cu fractions are assumed to be available for uptake, and as both fractions depend on pH, a pH dependency of copper uptake and accumulation is expected. In recent studies with springtails this dependency was not observed. To explain this, we show that both the adsorption of copper by yeast and by soil is indeed pH dependent; however, these dependencies differ. Addition of yeast as a food source to copper-contaminated soil leads to competition for copper by yeast and soil that suppresses the pH dependency of copper adsorption by yeast. This may cause a pH dependency not to be observed in copper accumulation by springtails if they predominantly feed on yeast in bioassays. We conclude that the addition of artificial food sources in bioassays may affect the cause-effect relationships that are investigated. A combination of (soil) chemical experimentation and modeling and ecotoxicological studies may help in identifying such bias and, therefore, with interpreting bioassays.

Metal Compartmentation and Speciation in a Soil Sentinel: The Earthworm,Dendrodrilusrubidus

“…Such measurements have led to the formulation, for freshwater systems, of biotic ligand models (BLM) that predict the toxic effects of a metal from measured site-specific physicochemical parameters (44,45). In principle, BLMs could be derived for earthworms despite the complexity and heterogeneity of soil matrixes, as implied by recent studies defining the Cu relationships of a collembolan (46) and establishing soil critical limits based on free ion concentrations (47,48), respectively. Compartment 2 relationships have received sparse direct investigations in terrestrial invertebrates (15), although Oste et al (49) and Saxe et al (50) presented models describing metal accumulation, if not uptake, by earthworms.…”

Toxicity benchmarks for antimony, barium, and beryllium determined using reproduction endpoints forFolsomia candida,Eisenia fetida, andEnchytraeus crypticus

“…The effects of such contamination on soil invertebrates have been studied extensively for several decades. These studies have included assessments of impacts along heavy‐metal gradients from point sources, such as smelters [1–4]; impacts from non‐point‐source pollution, including application of metal‐based pesticides or metal‐containing sludge [5,6]; and laboratory toxicity tests with amended natural soil [7–9] or standard artificial soil [10–14]. With the exception of a few studies using natural soil types that supported high bioavailability of metals and standardized toxicity tests, the majority of metal toxicity data developed in studies with field‐contaminated soils do not meet the data‐quality objectives for establishing ecotoxicological benchmarks that could be applied directly to ecological risk assessment (ERA) of contaminated Superfund sites.…”

Metal uptake by Lolium perenne in contaminated soils using a four‐step approach

“…It has been shown previously that the Ni uptake by oat shoots was higher when the pH of these soils decreased [15]. Van der Zee et al [26] showed that Cu adsorption by yeast increased at increasing pH when the yeast was exposed to the CaCl 2 extractions of the Wildekamp soils. Lexmond [18] showed that Cu toxicity to maize on these Wildekamp soils decreased at increasing pH, but that the increasing toxicity was smaller than would be expected from the reduction in Cu 2+ activity in the soil solution.…”