Equilibrium partitioning of heavy metals in dutch field soils. II. Prediction of metal accumulation in earthworms

Abstract

Abstract-To evaluate the adequacy of the equilibrium partitioning concept in predicting metal bioaccumulation, a soil invertebrate species was exposed in 20 Dutch field soils with moderate metal contamination. Earthworms (Eisenia andrei) were kept in the soils for 3 weeks under laboratory conditions. Bioconcentration factors (BCFs) for six metals (Zn, Cu, Pb, Cd, Cr, Ni) and for As were calculated as the ratio of body-and solid-phase metal concentrations. Multivariate statistical analyses suggested that the BCFs for As, Cd, Cu, and Zn are governed by the same soil characteristics that determine equilibrium partition coefficients between the soil solid phase and the pore water. This suggests that uptake of metals is either direct from the pore water or indirect through an uptake route closely related to pore water. Regression equations were derived for predicting BCF values as a function of easily determinable soil characteristics. By means of internal validation it was shown that the equations obtained can be used for predictive purposes within the range of soil properties encountered in the dataset. Due to a lack of data, external validation was possible only in a qualitative sense.

Determining the bioavailability and toxicity of lead contamination to earthworms requires using a combination of physicochemical and biological methods

“…Bradham et al (2006) argued that the apparent correlation of earthworm survival with CEC may be caused by the strong inter-correlation between CEC and other exogenous variables such as pH, and not by a direct effect of CEC (see e.g., Criel et al, 2008). Earthworm mortality was not significantly correlated with organic matter content or DOC concentration in the porewater, which agrees with other studies (Bradham et al, 2006;Janssen et al, 1997;Peijnenburg et al, 1999). Simple and stepwise regression analysis showed that the number of surviving of adult earthworms (SN) was well predicted on the basis of the porewater Pb concentrations, CEC, silt and sand contents of the test soils (Table 4).…”

“…Internal Pb concentrations did not correlate with soil OM content, but they significantly and negatively correlated with DOC level in the porewater. In addition, internal Pb was negatively correlated with clay content and silt content but positively with Fe and sand content, which all have been shown also by others to be modifying Pb uptake by earworms (Janssen et al, 1997;Peijnenburg et al, 1999;Basta et al, 2005).…”

Assessing the ecotoxicological effects of long-term contaminated mine soils on plants and earthworms: relevance of soil (total and available) and body concentrations

“…The influence of the total and available concentrations on organism accumulation has been discussed in different articles, and the results are contradictory. Some studies revealed a dependence of the metal burden on worms (Peijnenburg, 1999;Janssen, 1997) and plants (Smith et al, 2012) with the total concentrations, whereas others (García-Salgado et al, 2012) found a dependence on the extractable concentrations. Pignattelli (2012) found a correlation between the As content in plants with the total and available concentrations, whereas the Zn and Cu accumulation was irrespective of both external concentrations.…”

Lead toxicity thresholds in 17 Chinese soils based on substrate-induced nitrification assay

“…Broos et al (2007) also developed a regression model using pH (r 2 adj = 0.73) and CEC (r 2 adj = 0.63) for the SIN assay. Soil pH and CEC have been widely recognized as the most important soil properties determining the partitioning of Pb in soils (Bradham et al, 2006;Buchter et al, 1989;Janssen et al, 1997;Peijnenburg et al, 1999). Buchter et al (1989) found that pH and CEC were significantly correlated with Kp (partition coefficient) values for 15 elements.…”

“…Buchter et al (1989) found that pH and CEC were significantly correlated with Kp (partition coefficient) values for 15 elements. Janssen et al (1997) showed that soil pH was the most important soil characteristic affecting Pb partitioning between the soil solid phase and soil pore water after studying the effect of soil properties on Pb uptake by earthworms in 20 contaminated field soils. Van den Hoop (1995) determined Kp values for Cu, Ni, Pb, Zn and Cd in field soils by analyzing element concentrations directly in the pore water, and found that the Kp values correlated well with CEC.…”