Abstract:

Chlorinated paraffins (CPs) present a complex mixture of congeners which are often analysed and assessed as short-, medium- and long-chain CPs, i.e. ΣSCCP (C₁₀–C₁₃), ΣMCCP (C₁₄–C₁₇) and ΣLCCP (≥C₁₈). Their complexity makes the chemical analysis challenging, in particular in terms of accurate quantification, but promising developments involving ultra-high resolution mass spectrometry have been presented lately. Most Arctic data exist for SCCPs, while LCCPs have not yet been studied in the Arctic. ΣSCCP concentrations in Arctic air often exceeded those of ΣMCCP, usually with a predominance of the most volatile C₁₀ congeners, and of banned persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs). The presence of SCCPs and MCCPs in Arctic air, as well as in the Antarctic and in the remote regions of the Tibetan plateau, provides evidence of their long-range transport including sufficient environmental persistence to reach the Arctic. Arctic vegetation accumulated SCCPs partly from air and partly through root uptake from soil, with consequences for the SCCP profile found in Arctic plants. No results have yet been reported for CPs in terrestrial Arctic animals. Results for freshwater sediment and fish confirmed the long-range transport of SCCPs and MCCPs and documented their bioaccumulation. Where additional PCB data were available, ΣPCB was usually higher than ΣSCCP in freshwater fish. Both SCCPs and MCCPs were widely present in marine Arctic biota (e.g. mussels, fish, seabirds, seals, whales, polar bears). In mussels and Atlantic cod, ΣMCCP concentrations exceeded those of ΣSCCP, while this was less clear for other marine species. Marine mammals and the long-lived Greenland shark roughly had ΣSCCP concentrations of 100–500 ng/g lipid weight, often dominated by C₁₁ congeners. Biomagnification appeared to be more pronounced for ΣSCCP than for ΣMCCP, but more studies will be needed. Increasing ΣSCCP concentrations were observed in Arctic air and sediment over time, but not in beluga monitored since the 1980s. For both SCCPs and MCCPs, increasing concentrations over time have been shown in blue mussels and Atlantic cod at some, but not all stations. Indications exist of local sources of SCCPs in the Arctic, including Arctic settlements and research stations. In studies involving multiple locations, a general decrease of SCCP concentrations with increasing latitude or distance from point sources was observed as well as relatively more MCCPs at locations closer to potential CP sources. Monitoring of SCCPs and MCCPs has been initiated in some Arctic regions and will be important to assess the effect of recent regulations of SCCPs and the use of potential replacement chemicals.

https://doi.org/10.1016/j.emcon.2019.06.001