Morton Arboretum Bioassays: Earthworm Bioassay Procedures to Evaluate the Extent of Aerially Dispersed Lead and Cadmium in an Urban Arboretum

摘要

Aerially dispersed heavy metals from a high speed motorway have been shown to be entering an urban arboretum. Lead (Pb) and Cadmium (CD) were found as remote as 930 m from an east-west, multi-lane motorway. Both Pb and Cd were bioavailable to earthworms (Eisenia foetida) and both metals were more concentrated in surface soils than at depths of 1 meter. Seven sampling stations were established at progressive intervals along the 930 m transect. At all sampling stations, soil cores 15 cm deep and replicated four times were collected. The sod was removed from each sample except for one station 33 m away from the motorway. This was retained and tested along with some additional 1 m depth soil cores. All samples were transported to the U.S. Army Engineer Waterways Experiment Station (WES) where bioassay tests utilizing the earthworm (Eisenia foetida) were conducted under controlled conditions.