Ecotoxicology of copper and cadmium in a contaminated grassland ecosystem. II. Invertebrates.
Invertebrates from contaminated and semi-contaminated grasslands in the vicinity of a major copper refinery housing copper/cadmium alloying plant all showed significant elevation of total body copper and cadmium concentrations relative to control values. Cadmium concentrations in the major taxa were, ranked in decreasing order, as follows: Isopoda, Oligochaeta, Lycosidae, Opiliones, Linyphiidae, Collembola, Carabidae, Staphylinidae, Chilopoda, Curculionidae and Orthoptera. Copper concentrations in the major taxa were, ranked in decreasing order, as follows: Isopoda, Collembola, Oligochaeta, Linyphiidae, Opioliones, Lycosidae, Chilopoda, Curculionidae, Carabidae, Staphylinidae and Orthoptera. newline˜Detritivorous soil macrofauna showed accumulation of copper (2-4 times) and cadmium (10-20 times) with respect to concentrations in refinery site organic surface soil and plant litter. Oligochaeta and Isopoda both showed a significant reduction in population size at the refinery site. Herbivorous invertebrates showed body:diet concentration factors of 2-4 times for copper and 3-5 times for cadmium. Results showed a degree of homeostatic control over accumulation of copper in contrast to the pattern for cadmium. Biotransfer of metals to carnivorous invertebrates reveals marked differences in metal accumulation by predatory beetles and spiders. The copper:cadmium concentration ratio in predatory beetles was 30-35:1 compared with 9-11:1 in spiders. newline˜Among the invertebrates with the highest levels of cadmium accumulation, arachnids, in contrast with isopods, and in particular lycosid spiders, were abundant and frequently encountered in refinery grasslands. Predation on spiders, therefore, represents a potential major pathway for the accumulation of cadmium by predatory small mammals and birds.