Sea spray as a secondary source of chlorinated persistent organic pollutants? - Conclusions from a comparison of seven fresh snowfall events in 2019 and 2021

Secondary sources of persistent organic pollutants (POPs) gain in importance worldwide as primary sources decline. In this work, we aim to determine whether sea spray may be a secondary source of chlorinated POPs to the terrestrial Arctic, since a similar mechanism was proposed there only for the more water-soluble POPs. To this end, we have determined polychlorinated biphenyls and organochlorine pesticides concentrations in fresh snow and seawater collected in the vicinity of the Polish Polar Station in Hornsund in two sampling periods covering spring 2019 and 2021. To support our interpretations, we include also metal and metalloid, and stable hydrogen and oxygen isotopes analysis in those samples. A significant correlation was found between the concentrations of POPs and the distance from the sea at the sampling point, yet the confirmation of sea spray impact lies more in capturing an event with negligible long-range transport influence where the detected chlorinated POPs (Cl-POPs) matched in composition the compounds enriched in the sea surface microlayer, which is both a source of sea spray and a seawater microenvironment rich in hydrophobic substances. [Display omitted] •Fresh snow and seawater microlayer sampled for chlorinated POPs concentrations•Two years of spring Arctic snowfall showed vastly different Cl-POPs concentrations.•2019 impacted by long-range transport (LRT) while 2021 showed mainly local factors.•POPs compounds enriched in seawater microlayer were predominant in 2021 snow.•Sea spray transports Cl-POPs inland in the Arctic, yet LRT dominates Cl-POP fluxes.