Source-Exposure Relationships for Airborne Organic Contaminants of Emerging Concern in Northern Terrestrial and Freshwater Ecosystems

There is both scientific and regulatory interest in identifying man-made chemicals which may represent a risk for environmental and human health. Some chemicals can travel long distances to remote areas, such as the Arctic, via the air. Although many substances are recognized to be toxic and now regulated, e.g. many of the so-called persistent organic pollutants (POPs), there are indications that the number of potential POPs found in our environment exceeds those identified and regulated to date. In this project, we have studied relationships between sources of various Airborne Organic Contaminants of emerging concern (AOCs), and their occurrence in air, terrestrial and freshwater ecosystems. AOCs selected for this project included Dechlorane Plus and analogs (DPs), short- and medium chained chlorinated paraffins (SCCPs and MCCPs) and a range of "new" brominated flame retardants (nBFRs). We have carried out targeted air measurements of AOCs based on a model-based forecast system to explore the utility of an atmospheric model to track primary sources and source regions of AOCs. The project has also greatly benefited from passive air samples which were collected across Norway (N=45) and 32 European countries (N=107) as part of another NFR-project (244298). For this project, we expanded the target analytes to also include the selected AOCs. This research combined has allowed us to study both spatial and temporal patterns of selected AOC in background air, leading to a better understanding of the key sources and source regions controlling atmospheric burdens. As many of the studied AOCs are used world-wide in electrical and electronic equipment, we hypothesized that this may be a significant source of many AOCs. The project has therefore also included studies on the occurrence and emissions of AOCs as well as other chemicals from relevant recycling activities. We have also studied relationships between observed concentrations of AOCs in air and the occurrence in terrestrial and freshwater ecosystems. Soils play an important role in the fate of AOCs in terrestrial systems because they have the ability to sorb and store large amounts of these contaminants. The occurrence of selected AOCs in surface soils from 45 remote sites across Norway and in 10 urban samples were analyzed for selected AOCs, and their environmental fate and behavior (e.g. association with soil organic matter, spatial distribution, environmental processes) were analyzed to assess the anticipated effect of highly populated areas on AOC-burdens in soils. All selected groups of AOCs were detected in soils. MCCPs were detected with the highest concentrations, followed by SCCPs, DPs and the sum of 15 nBFRs. These results present valuable information on the atmospheric deposition and spatial variability of selected AOCs within the terrestrial environment. For freshwater environments, field work has been carried out in an urban lake (Storvannet, Hammerfest) and a remote lake (Takvannet, Troms) in northern Norway. While occurrences of AOCs in the latter lake is expected to primarily be a result of long-range atmospheric transport, Storvannet has a history of high concentrations of regulated POPs. This difference facilitated a direct comparison of contaminant burdens in limnic systems in both urban and more remote areas, as well as further opportunities to study bioaccumulation of selected AOCs across lakes. Samples of sediment, benthic organisms, three-spined sticklebacks (Gasterosteus aculeatus), Arctic char (Salvelinus alpinus) and brown trout (Salmo trutta) have been collected from both lakes. All samples were analysed for selected AOCs, including SCCPs and MCCPs and Dechlorane Plus and related analogues. Additionally, the samples were analyzed for polychlorinated biphenyls (PCBs) as a reference substance. Other biological parameters, such as such as lipid content and stable isotopes were analysed in order to standardize data and to assess bioaccumulation and biomagnification. The results showed considerably higher concentrations of AOCs in Storvannet than in Takvannet, confirming that the two lakes have different exposure profiles, i.e. that Storvannet is also receiving AOCs from local sources. Detection of Dechlorane Plus syn and anti, Dechlorane 602 and Dechlorane 603 in Takvannet suggested that these compounds may undergo long-range atmospheric transport to northern freshwater ecosystems. However, of these, only Dechlorane 602 showed potential for trophic magnification. SCCPs and MCCPs were detected in both lakes, with generally higher concentrations of MCCPs, mirroring the results from the analysis of soil samples. This also confirmed that SCCPs and MCCPs may undergo long-range atmospheric transport to northern freshwater ecosystems. However, concentrations in the top-predatory fish (char and trout) were often below detection limits, indicating that SCCPs and MCCPs do not undergo trophic magnification.

Rasjonelle kjemikaliestrategier på global skala som har som mål om å beskytte mennesker og miljø mot helseskadelige stoffer fordrer en forståelse mellom kilder og eksponering. Prosjektet har ledet til økt tverrfaglig forskningssamarbeid innen dette forskningsfeltet, både nasjonalt og internasjonalt. Nasjonale og internasjonale miljømyndigheter har allerede utvist interesse for prosjektets foreløpige resultater. De endelige resultatene for enkelte komponenter som ble studert i prosjektet kan potensielt ha innvirkning på politikkutforming innen miljøgiftfeltet.

Persistent Organic Pollutants (POPs) are contaminants often found at surprisingly high levels in remote areas, including northern ecosystems. While several POPs are now regulated under international agreements in order to protect environmental and human health, there is an increasing scientific and regulatory interest in the possible risk posed by various organic contaminants of emerging concern. Contaminants of emerging interest are generally characterized by insufficient knowledge with regard to their sources, pathways, occurrence, distribution, fate and bioaccumulation behaviour in northern ecosystems. In this project we will target "airborne" organic contaminants of emerging concern (AOCs) which may be prone to accumulate in terrestrial and/or freshwater ecosystems as a result of atmospheric transport and deposition. While past experience have demonstrated the utility of relevant tools for legacy POPs, the applicability of existing methods remains to be further developed and evaluated for AOCs. In this project, we aim to develop, evaluate and apply a novel multidisciplinary framework to understand and predict air-exposure relationships. The scientific vision behind this project is to describe mechanistically the key steps assumed influential in a molecule's journey from atmospheric source regions to its uptake and accumulation in representative ecosystems (air-exposure relationships). Two intimately linked research pillars are planned for which atmospheric source-receptor relationships and air-exposure relationships are to be studied, respectively. Each pillar will rely on a combination of empirical and theoretical (modelling) studies that are to be carried out in an iterative fashion to help identify key knowledge gaps as the project progresses. As an intended outcome of this research project, we hope to offer scientific advice to inform rational chemical management strategies.