Bioavailability and Ecotoxicity of Lead in Soil: Implications for Setting Ecological Soil Quality Standards

Abstract

Ecological soil quality standards for lead (Pb) that account for soil Pb bioavailability have not yet been derived. We derived such standards based on specific studies of the long-term bioavailability and toxicity of Pb to soil organisms and a compilation of field data on the bioaccumulation of Pb in earthworms. Toxicity thresholds of Pb to plants, invertebrates, or microorganisms vary over more than 2 orders of magnitude, and the lowest values overlap with the range in natural Pb background concentrations in soil. Soils freshly spiked with Pb 2+ salts exhibit higher Pb bioavailability and lower toxic thresholds than long-term aged and leached equivalents. Comparative toxicity tests on leaching and aging effects suggest using a soil Pb threshold that is 4.0 higher, to correct thresholds of freshly spiked soils. Toxicity to plants and earthworms, and microbial N-transformation and bioaccumulation of Pb in earthworms increase with decreasing effective cation exchange capacity (eCEC) of the soil, and models were derived to normalize data for variation of the eCEC among soils. Suggested ecological quality standards for soil expressed as total soil Pb concentration are lower for Pb toxicity to wildlife via secondary poisoning compared with direct Pb toxicity to soil organisms. Standards for both types of receptors vary by factors of approximately 4 depending on soil eCEC. The data and models we have collated can be used for setting ecological soil quality criteria for Pb in different regulatory frameworks.

Fate and Exposure Assessment of Pb Leachate from Hypothetical Breakage Events of Perovskite Photovoltaic Modules

“…On the other hand, Oorts et al attempted to quantify the role of Pb 2+ bioavailability on ecological soil quality standards and found that soils freshly spiked with Pb 2+ salts similar to those in perovskite PV exhibited higher Pb bioavailability and lower toxic thresholds than long-term aged and leached equivalents . The results of the comparative toxicity tests of the study indicate that Pb soil screening thresholds could be increased by up to a factor of 4 compared to thresholds determined using freshly spiked soils.…”

Epigallocatechin Gallate Modulates Essential Elements, Zn/Cu Ratio, Hazardous Metal, Lipid Peroxidation, and Antioxidant Activity in the Brain Cortex during Cerebral Ischemia

“…Accumulating evidence indicates that the mechanism underlying Pb toxicity involves elevated oxidative stress due to ROS production and antioxidant capacity depletion [ 42 , 43 ]. In this present experiment, we observed that the brains of rats pretreated with EGCG before ischemic injury had lower Pb concentrations than did those from untreated ischemic injury rats.…”

Assessment of Current Risks of Excessive Heavy Metal Accumulation in Soils Based on the Concept of Critical Loads: A Review

“…However, the difficulties in studying the HM partitioning between the soil solid phase and solution remain for the real soil-to-solution ratios under field conditions. In particular, the latter include the addition of soluble HM salts in laboratory adsorption and ecotoxicological experiments that ignore the longterm processes of metal binding and a decrease in their bioavailability, characteristic of the field conditions [61,65,75,87,93]. The efforts to model the ageing process depending on soil properties and duration of interaction are necessary [110].…”