Trapping pollutants

Now, an international research team has showcased, in a new paper in Environmental Science & Technology, the potential of a technique known as passive sampling in which a polymer film absorbs toxic chemicals from contaminated sediments and measures their levels in a way that can help monitor risks associated with them over a prolonged period.¹ 

Passive sampling allows the free flow of molecules from contaminated sediment to the polymer film in a sampling device. A difference in chemical potential between the sediment and the film drives the flow of the molecules towards the film, essentially trapping them.

The chemicals are extracted from the film using a solvent, which is then chemically analyzed.

Since the tool doesn’t require an external energy source to function, passive sampling can be used freely in the field. Besides sediments, it could potentially detect toxic chemicals in air and water and even help in mapping exposure to such chemicals in humans.

The research team, including scientists from Egypt, compared 14 different passive sampling formats across different labs, successfully quantifying the concentrations of 25 toxic chemicals in river sediments.

“For the first time, this elaborate study validates the utility of the passive sampling technique in monitoring the levels of toxic chemicals in sediments across different laboratories,” says lead author Michiel T.O. Jonker from the Utrecht University, the Netherlands. 

Graham Mills from the University of Portsmouth, UK, who is not involved in the research, says that "this work will go a long way to convince regulators and other end-users [of] the power of passive sampling, creating national or even international guidelines on the subject of environmental risk assessments.”

Unlike other methods that overestimate the risks of contaminated sediments, leading to unnecessary clean-ups of contaminated sites, passive sampling has the potential to properly assess the actual risks of sediment contamination, saving huge clean-up costs, adds Jonker. 

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