Contamination of the O2 Soil Horizon by Zinc Smelting and its Effect on Woodlouse Survival

Abstract

Samples of litter from the O2 horizon of Dekalb soil (loamy‐skeletal, mixed, mesic Typic Dystrochrept) were collected from 18 ridgetop sites on a transect that ran by two Zn smelters in Palmerton, Pa. Metal concentrations increased by regular gradations from a minimum at a site 105 km west of the smelters (67 mg/kg Zn, 0.85 mg/kg Cd, 150 mg/kg Pb, 11 mg/kg Cu) to a maximum 1.2 km east of the smelters (35 000 mg/kg Zn, 1300 mg/kg Cd, 3200 mg/kg Pb, 280 mg/kg Cu), and then decreased until they reached an eastern minimum at the easternmost site, 19 km from the smelters. An increase in the P concentrations near the smelters showed that the emissions were disrupting nutrient flow through the ecosystem. An increase in the pH near the smelters was attributed to the high concentrations of Zn. The log of the distance of the sites from the smelters was significantly correlated ( r = −0.80, p < 0.05) with the mortality of woodlice ( Porcellio scaber Latreille) fed samples of the litter during an 8‐week test. There was substantial mortality of woodlice observed even in the O2 litter collected 19 km east of the smelters. Zinc, cadmium, lead, copper, and sulfur were experimentally added, alone or in combination, to O2 litter collected far from any known source of metal emissions. The highest concentration of Zn added (20 000 mg/kg) was toxic enough to account for the mortality observed in the earlier test. A lower concentration of Zn (5000 mg/kg) as well as the concentration of Cd (500 mg/kg) tested also significantly ( p < 0.05) increased the mortality of woodlice.