Persistent organic pollutants in sediments of high-altitude Alpine ponds within Stelvio National Park, Italian Alps

The concentrations of persistent organic pollutants (POPs), such as dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs), were investigated in sediments collected in 25 high-altitude Alpine ponds within Stelvio National Park, Italy. The total PAH concentrations in the lake sediments ranged from 27.8 to 5644 ng/g dry weight (dw), with the ratio between low and high molecular weight PAHs (LMW-PAHs/HMW-PAHs) indicating inputs from both pyrogenic and petrogenic sources (mostly fossil fuel combustion). Limited concentrations of PBDEs (less than the limit of detection [LOD] to 9.9 ng/g dw), PCBs (<LOD-40.9 ng/g dw), and DDx (sum of DDE+DDD+ DDT; <LOD-4.75 ng/g dw) were measured in the sediments, and the ratio (? o,p'+ p,p'- DDE +?o,p'+ p,p'- DDD)/? o,p'+ p,p'- DDT indicated an overall-aged contamination of the analyzed samples. Potential sources of POP and PAH contamination in the sediments were further investigated by diff erent statistical analysis, confirming the primary role played by the medium-range atmospheric transport (MRAT) mechanism in the transfer of POPs to remote Alpine regions. Our results showed that the analyzed sediment samples can be considered slightly contaminated by the target compounds, with concentrations comparable to those detected in other remote areas.