Toxicity of Pb contaminated soils to the oribatid mite Platynothrus peltifer.

To understand the toxicity of Pb-polluted shooting fields, oribatid mites Platynothrus peltifer were exposed to shooting field soils containing 47-2398 mg Pb/kg dry weight (DW) and having pH(CaCl2) 3.2-6.8 and 3.8-13% organic matter (OM). Exposures also included artificial soils with different pH and OM contents as well as two natural soils used as controls. Exposures lasted for 2 (acute) and 12 weeks (chronic). Survival, reproduction and uptake of Pb in the mites were related to total, water-extractable and 0.01 M CaCl2-extractable and porewater Pb concentrations as well as soil characteristics. After both the acute and chronic exposures, adult survival was not significantly affected, while upon chronic exposure reproduction was remarkably reduced in the acidic forest soils with Pb concentrations ≥2153 mg/kg DW and pH(CaCl2) ≤ 3.5. P. peltifer juvenile numbers were significantly negatively and internal Pb concentrations in the mites were significantly positively related with total, extractable and porewater Pb concentrations. This study shows that P. peltifer is not very sensitive to Pb and therefore may not be a suitable indicator of Pb-polluted soils.