T. Komarova

Using SPMDs to monitor water column concentrations of PCDDs, PCDFs and dioxin-like PCBs in Port Jackson (Sydney Harbour), Australia.

Semipermeable membrane devices (SPMDs) were deployed on two occasions throughout Sydney Harbour, Australia, along a 25 km transect. They were used to measure spatial and temporal variation in the available concentrations of 7 polychlorinated dibenzo-p-dioxins (PCDDs) and 10 polychlorinated dibenzofurans (PCDFs) and 12 dioxin-like polychlorinated biphenyls (PCBs) in the water column. The relative percent difference (%RPD) among spatially replicated cages (within 0.13-0.41 km) ranged from less than 8% to greater than 66% across all congeners and was greater for WHO(05)-TEQ(DFP) (average=36%), PCDFs (average=34%) and PCDDs (average=33%) than PCBs (average=23%). Total PCDD (SigmaPCDDs) concentrations ranged between 2.7 and 84 pg L(-1), SigmaPCDF concentrations ranged from 0.15 to 7.2 pg L(-1), SigmaPCB concentrations ranged between 21 and 540 pg L(-1) and WHO(05)-TEQ(DFP) ranged from 0.069 to 1.85 pg L(-1). Highest concentrations were measured in SPMDs deployed in Homebush Bay and concentrations generally declined with distance from Homebush Bay. SPMDs detected changes in congener profiles downstream with OCDD, 2,3,7,8-TCDF and PCBs 189, 157, 167, and 126 increasing in proportion with distance from Homebush Bay. There was a large increase in the daily accumulation of the analytes from winter to summer resulting in an average 3.9-fold increase in the predicted concentration at one site with matched SPMDs.

Evaluation and in situ assessment of photodegradation of polyaromatic hydrocarbons in semipermeable membrane devices deployed in ocean water.

Semipermeable membrane devices (SPMDs) were deployed in water using four different methods: a typical SPMD cage with and without a mesh cover, a bowl chamber and without any protection. In addition to routinely used performance reference compounds (PRCs), perdeuterated dibenz[a,h]anthracene was added. Due to its high sampler to water partition coefficient no measurable clearance due to diffusion was expected during the deployment period, hence any observed loss could be attributed to photodegradation. The loss of PRCs was measured and SPMD-based water concentrations determined. Results showed that a typical SPMD deployment cage covered with mesh provided the best protection from photodegradation. Samplers which had undergone the highest photodegradation underestimated PAH water concentrations by up to a factor of 5 compared to the most protected SPMDs. This study demonstrates that the potential for photodegradation needs to be addressed when samplers are deployed in water of low turbidity.

FIELD EVALUATION OF PASSIVE SAMPLERS: MONITORING POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN STORMWATER

Abstract The aim of this study was to evaluate the feasibility of using semipermeable membrane devices (SPMDs) and polyethylene-based passive sampler devices (PSDs) for monitoring PAHs in stormwater. Firstly, SPMDs were deployed at one site and SPMD-derived water concentrations were compared with water concentration measured from grab samples. In a subsequent deployment the performance of SPMDs and PSDs was compared. Finally PSDs of multiple surface area to volume ratios were used to compare PAH concentrations at the two sites. The results obtained in this study show that SPMDs can be used to measure the water concentration of PAHs with reasonable accuracy, when compared with grab samples collected at the same site. Importantly, several PAHs which could not be detected in a 10 L grab sample could be detected in the SPMDs. PSD and SPMD samplers produced similar results when deployed at the same site, with most estimated water concentrations within a factor of 1.5. The use of PSDs in multiple surface area to volume ratios proved to be an effective means of characterizing the uptake kinetics for PAHs in situ. Overall passive water samplers proved to be an efficient technique for monitoring PAHs in stormwater.

A cleaner river: long term use of semipermeable membrane devices demonstrate that concentrations of selected organochlorines and PAHs in the Brisbane River estuary, Queensland have reduced substantially over the past decade.

We first used semipermeable membrane devices as samplers to evaluate concentrations of organochlorines and PAHs in the Brisbane River in 1998. Here we revisit this work and repeat the study a decade later in the same season (summer), also taking account of results from a similar study involving PAHs in the summer of 2001-2002. The accumulation of organochlorines and most PAHs in the samplers in the recent assessment was substantially less than in the 1998 deployment, suggesting that the ambient concentrations of these chemicals have decreased considerably over the last decade. In all cases there was high reproducibility of the mass of chemicals accumulated in the sampler. We used performance reference compounds in the later deployment, and assuming that the kinetics were similar in both deployment periods, we estimate that the concentration of dieldrin, the organochlorine found at highest concentrations, decreased from approximately 3.9 ng/L to about 1.4 ng/L. The decrease of most other analytes of interest including DDE and DDD was greater, potentially indicating that dieldrin is still entering the Brisbane River through run-off from urban areas where it was used widely for treatment of termites until 1995. DDT use in Australia ceased in the mid 1980s.