Trace Element and Organohalogen Compound Contamination in the Supraglacial Debris of Italian Glaciers

Glaciers represent unique and threatened ecosystems, which have accumulated and continue receiving diverse, potentially toxic, and environmental contaminants released by past and ongoing anthropic activities. The accelerated ablation and retreat of glaciers due to climate warming can consequently alter the fate of contaminants trapped within their ice or on their surface, leading to increased contaminant release through meltwaters. Thus, the monitoring of glacier contaminants is crucial for assessing the potential risk for proglacial ecosystems. The present study aimed at investigating the presence and distribution of organic and inorganic contaminants in supraglacial debris from sixteen Italian glaciers. The levels of organohalogen compounds, specifically organochlorine (i.e., DDT homologues, HCH isomers, HCB, and PCBs) and polybrominated diphenyl ethers (i.e., PBDEs), and trace elements (i.e., Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sr, Ti, Va, and Zn) were investigated in the debris collected from fifteen Alpine glaciers and the only existing Apenninic glacieret. The supraglacial debris of all glaciers contained measurable concentrations of trace elements, while organohalogen compounds were detected at measurable concentrations only in certain glaciers. Fe (mean ± standard deviation: 22,781.46 ± 10,849.73 mg/Kg dry weight), Al (10,417.71 ± 6,019.36 mg/Kg d.w.), and Mn (312.52 ± 167.78 d.w.) were the predominant trace elements, but measurable concentrations of toxic metals such as Cd (0.23 ± 0.31 d.w.), Hg (0.16 ± 0.12 d.w.), and Pb (84.32 ± 110.04 d.w.) were detected in the debris of all glaciers. The DDT homologues (mean ± standard deviation: 0.006 ± 0.009 mg/Kg d.w.), PCBs (0.003 ± 0.004 d.w.), and HCB (0.0009 ± 0.0005 d.w.) were measured in less than the 75% of investigated glaciers, while HCH isomers and PBDEs were never measured. Overall, a wide variability in the levels of all the investigated contaminants was observed among glaciers, suggesting that their origin could depend on atmospheric transport but also local sources of contamination.