Evidence for the presence of a widespread PCDD source in coastal sedimentsand soils from Queensland, Australia

Recent studies have demonstrated the occurrence of elevated levels of highe r chlorinated PCDDs in the coastal environment of Queensland, Australia. Th is study presents new data for OCDD contamination and full PCDD/F profile a nalysis in the environment of Queensland. Marine sediments, irrigation drai n sediments and topsoil were collected from sites that were expected to be influenced by specific land-use types. High OCDD concentrations were associ ated mainly with sediments collected near the mouth of rivers which drain i nto large catchments in the tropical and subtropical regions. Further, anal ysis of sediments from irrigation drains could be clearly differentiated on the basis of OCDD contamination, with high concentrations in samples from sugarcane drains collected from coastal regions, and low concentrations in drain sediments from drier inland cotton growing areas. PCDD/F congener-spe cific analysis demonstrated almost identical congener profiles in all sampl es collected along the coastline. This indicates the source to be widesprea d. Profiles were dominated by higher chlorinated PCDDs, in particular OCDD whereas 2,3,7,8-substituted PCDFs were below the limit of quantification in the majority of samples. The full PCDD/F profile analysis of samples stron gly resemble those reported for lake sediments from Mississippi and kaolini te samples from Germany, Strong similarities to these samples with respect to congener profiles and isomer patterns may indicate the presence of a sim ilar source and/or formation process that is yet unidentified. (C) 2001 Els evier Science Ltd. All rights reserved.