Passive sampling and modeling of PAHs and heavy metals in stormwater runoff

Requirements in the European Water Framework Directive include monitoring of priority substances in the aquatic environment. Use of passive samplers for monitoring purposes in the highly dynamic storm sewer systems is limited by the time-proportional sampling adopted by the majority of the available samplers.

This paper reports the preliminary results from work with the SorbiCell passive sampler, which samples runoff with a velocity-proportional approach. The inlet and outlet of a retention pond was monitored by using autosamplers and SorbiCell passive samplers. Total concentrations of PAHs in samples from the autosampler ranged from LOD - 0.63 μg/L in the pond inlet and LOD - 0.08 μg/L in the outlet.

Dissolved concentrations of PAHs measured using the passive samplers at the inlet varied from LOD - 0.93 μg/L. Dissolved copper concentrations ranged from 4.7-22 μg/L according to the data from the autosamplers and between 18-43 μg/L according to the passive samplers. Dissolved lead and zinc concentrations ranged from 0.3-35 μg/L and 36-122 μg/L respectively.

The different sampling techniques were compared by using an integrated stormwater quality model. Representative samples can be obtained by using both sampling methods after an accurate definition of the sampling configuration (sampling frequency, flow velocity around the sampler).