Background soil concentrations of phenolic compounds, chlorinated herbicides, PCDDs and PCDFs in the Melbourne metropolitan area.

During June and July 1990, surface soil samples were taken in the Melbourne metropolitan area and analysed for phenolic compounds, chlorinated herbicides, polychlorinated dibenzo-para-dioxins (PCDDs) and polychlorinated furans (PCDFs). A surface soil sample from a Werribee Farm Treatment Complex paddock, where cattle graze on land that is used for filtration of sewage, was also taken and analysed. No phenolic compounds or chlorinated herbicides were detected at the parts per billion detection limits in any of the samples. PCDDs and PCDFs were detected in both industrial and nonindustrial sectors of the Melbourne metropolitan area, as well as in effluent from Nufarm Limited, an agricultural chemicals manufacturer in Laverton North, in similar concentrations (toxic equivalents in the parts per trillion range). These concentrations were consistent with background levels identified in other major urban areas. There was no evidence of the Nufarm effluent fingerprint in any of the background soil samples analysed. The fingerprint profile of the sample taken from Werribee Farm, although showing traces of the Nufarm effluent fingerprint, was clearly distinct from that effluent fingerprint and consistent with the fingerprint identified in the background soils. The impact of the Nufarm effluent on the area, therefore, was considered insignificant.