Per- and polyfluoroalkyl substances (PFAS) contamination in a microtidal urban estuary: Sources and sinks.

This study evaluates PFAS contamination and determines the major drainage sources to a temperate microtidal estuary, the Swan Canning Estuary, in Perth Western Australia. We describe how variability in these sources influences PFAS concentrations within this urban estuary. Surface water samples were collected from 20 estuary sites and 32 catchment sites in June and December from 2016 to 2018. Modelled catchment discharge was used to estimate PFAS load over the study period. Three major catchment sources of elevated PFAS were identified with contamination likely resulting from historical AFFF use on a commercial airport and defence base. Estuary PFAS concentration and composition varied significantly with season and spatially with the two different estuary arms responding differently to winter and summer conditions. This study has found that the influence of multiple PFAS sources on an estuary depend on the historical usage timeframe, groundwater interactions and surface water discharge.

Sensitivity of Daphnia carinata sensu lato to the insect growth regulator, pyriproxyfen.

This paper reports the sensitivity of Daphnia carinata sensu lato to pyriproxyfen, a promising chironomid control agent. Neonates exposed to pyriproxyfen in acute toxicity trials produced 48-hr LC50 of 0.08 ppm, eight times the concentration known to control the emergence of nuisance chironomids. However, continuous exposure to pyriproxyfen (0.01 ppm) during a 3-brood, 14-day life cycle test, suppressed the growth of D.carinata and reduced reproduction by as much as 80%.