Levels in soil, pasture and water at Lake Neerabup (unpublished data)
This monitoring study evolved from the treatment of a pasture adjoining Lake Neerabup, about 50km north of Perth for Argentine Ant control in early 1982. Shortly after pasture was sprayed, stock were returned to the pasture. Several cattle and horses died, as a result of acute heptachlor poisoning. Repeat treatments at different parts of the Lake occurred in 1983 and 1984.
The Entomology Branch of the Department has been regularly monitoring heptachlor and chlordane levels at a number of locations in Perth and in rural areas, in pasture, soil and water since that time.
While no results have been published, the study has provided much information on the degradation rates of these chemicals in the metropolitan environment. The results show that the initially high levels of heptachlor and chlordane in herbage fall to less than 1mg/kg within 12 months of application, but that residues after that time decline extremely slowly, and are likely to be detectable for some years to come.
P36/7 Monitoring Pesticides A Review. A Report to the Environment Protection Authority. Peter A Rutherford December 1989.