Environmental distribution and biodegradability of persistent organic pollutants in an open burning municipal solid waste site

The open dumping and burning of municipal solid waste (MSW) remain prevalent due to their low cost, despite posing serious risks to environmental and human health. This study assesses the contamination levels and the distribution of 22 persistent organic pollutants (POPs), including 13 polychlorinated biphenyls (PCBs) and 9 polycyclic aromatic hydrocarbons (PAHs) in and around an open burning MSW site in Mahdia, Tunisia. POP concentrations were quantified across different environmental matrices (i.e. surface water, sediment, soil, soil–leachate, fly ash and mallow plants) using gas chromatography coupled with single quadrupole mass spectrometry (GC-MS/MS). Furthermore, the OECD 301F manometric respirometry test was employed to evaluate the biodegradability of these compounds. Results revealed significant accumulation of POPs, particularly in fly ash and plant samples. Benzo[ghi]perylene and phenanthrene were identified as the predominant PAHs. The highest concentrations of PCBs and PAHs were found in fly ash (0.753 ± 3.54 μg per kg dry weight (dw) and 19.621 ± 26.76 μg per kg dw, respectively) and in plant material (0.378 ± 1.33 μg per kg dw and 42.563 ± 74.03 μg per kg dw, respectively), whereas surface water exhibited the lowest contamination levels. Biodegradability tests showed near-complete degradation (>90%) of POPs in surface water and mallow plant matrices over 28 days. In contrast, other matrices failed to exceed the 60% degradation threshold, classifying them as non-biodegradable.