Ecotoxicity assessment of particulate matter emitted from heavy-duty diesel-powered vehicles: influence of leaching conditions
Abstract
Concerns regarding the environmental impact of diesel exhaust particulate matter
(DPM) have increased in recent years. Following emission to the atmosphere, these
fine materials can sorb many contaminants at their surface, which can subsequently be
released, for instance, due to physico-chemical environmental changes. The
desorption of contaminants from particulate matter will increase the environmental
pollution and can promote ecotoxicological effects. In this context, the objective of this
study was to assess the aquatic ecotoxicity profile of extracts of DPM obtained at two
different pH values. Thus, after collecting particulate matter from the diesel exhaust of
heavy engines, extracts were obtained with pure water (at pH 2.00 and 5.00) and with
a mixture of three organic solvents (dichloromethane, n-hexane, and acetone). To
assess the environmental impact of DPM, the exhaust extracts were used in a battery
of aquatic bioassays including key organisms of the food chain: bacteria (Aliivibrio
fischeri), algae (Scenedesmus subspicatus), daphnids (Daphnia magna) and fishes
(Danio rerio). The aqueous leachate at natural pH (2.0) and solvent extracts were
extremely ecotoxic, while the aqueous leachate at pH = 5.0 showed the lowest
ecotoxicity. The global ranking of sensitivity for the biotests tested was: daphnids >
algae > bacteria > fishes. Thus, the use of this bioassay battery could improve our
understanding of the impact of DPM on aquatic environments, which is dependent on
the pH of the leaching process.