.JPG)
Abstract: Samples of water and sediments were collected from 24 urban wetlands in Melbourne, Australia, in April 2010, and tested for more than 90 pesticides using a range of gas chromatographic (GC) and liquid chromatographic (LC) techniques, sample ‘hormonal’ activity using yeast-based recombinant receptor-reporter gene bioassays, and trace metals using spectroscopic techniques. At the time of sampling, there was almost no estrogenic activity in the water column. Twenty-three different pesticide residues were observed in one or more water samples from the 24 wetlands; chemicals observed at more than 40 % of sites were simazine (100 %), atrazine (79 %), and metalaxyl and terbutryn (46 %). Using the toxicity unit (TU) concept, less than 15 % of the detected pesticides were considered to pose an individual, short-term risk to fish or zooplankton in the ponds and wetlands. However, one pesticide (fenvalerate) may have posed a possible short-term risk to fish (log10TUf > −3), and three pesticides (azoxystrobin, fenamiphos and fenvalerate) may have posed a risk to zooplankton (logTUzp between −2 and −3); all the photosystem II (PSII) inhibiting herbicides may have posed a risk to primary producers in the ponds and wetlands (log10TUap and/