I am also very grateful to all the members of the Environmental Chemistry group, IDAEA-CSIC. In the thesis, three studies on temporal and spatial gradients were carried out to deepen our understanding of OHCs accumulation in the fish and sediments of Greenland freshwater lakes. We found a strong influence of these seabirds in the transport and deposition of these hydrophobic compounds to remote sites.
We found a discriminating effect in seabird accumulation and transport of organohalogens to remote sites.
Resum
Arctic charr from Greenland against each of the normalized and centered predictor variables in the best models (lowest AIC model) of the multilevel linear regression (model results shown in Table 3): mean annual temperature (Tmean) and activity of the airport (Airport, Table SI -4). Greenland against each of the normalized Layman metrics (model results shown in Table 4): mean annual temperature (NR), airport activity (Airport) and fish length. 56 Table 7 Results of models showing a relationship between sum of OHC concentrations in sediments.
153 Table 25 Statistical parameters of the concentrations of the organohalogen compounds (in ng/g wet weight) found.
GENERAL INTRODUCTION AND OBJECTIVES
Introduction
The Arctic is one of the most susceptible areas on earth to both natural and human induced changes (Overpeck et al., 1997). Nevertheless, with the end of the cold war, these sites were mandated to support scientific research on the high Arctic (Goodsite et al., 2014). In addition, the Arctic is warming at an accelerated rate, much more than the rest of the world.
When fish are present in the lake, they are key players in structuring the food webs as they have a strong impact on the size, abundance and structure of the zooplankton in the lakes (Jeppesen et al., 2017).
General Objectives
Seabird-mediated transport of organohalogen compounds to remote sites
Northwest Greenland)
Occurrence and distribution of organohalogen compounds (OHCs) in freshwater
Long range transport and local effects enhance OHCs accumulation in Arctic Charr
Arctic charr is the main predatory fish in Greenland freshwater food webs (Jeppesen et al and forms an important component in the diet of the local population from this region (Kozak et al., 2021). Most of these studies have focused on temporal trends of the compounds studied, with the exception of Cleemann et al., annual mean air temperature data were obtained from the CRU TS high-resolution gridded monthly climate data set (Harris et al., 2020).
Specifically, our study and Cleemann et al. (2000) found that some charr individuals exceeded the toxicity threshold for PCBs and DDT; and half of our coal samples also exceeded toxicity thresholds set for PBDEs (Environment Canada, 1999). In the case of PBDEs, concentrations in remote lakes in Norway, such as those on the islands of Bjørnoya and Svalbard, have regularly shown low concentrations in Arctic carbon (Christensen et al., 2008; de Wit et al. Current and former military bases throughout the Arctic, particularly those with older RADAR equipment, have been identified in several studies as major contributors to Arctic pollution (Scrudato et al., 2012).
DDTs are also known to have been used at military bases and various communities in the Arctic to reduce the population of the biting insects (AMAP, 2004; Rawn et al., 2001). However, no statistical support for this mechanism was found in other studies in Arctic lakes (Gantner et al., 2010). These results indicate higher DDTs and PBDEs biomagnification when Arctic charr fed on multiple trophic positions, according to the food web biomagnification of persistent organic pollutants theory (Kelly et al., 2007).
This relationship between the trophic position of arctic char and the presence of sticklebacks in lakes was also described by Arranz et al (in preparation) in some studied lakes from Nuuk and Ilulissat. Arranz et al (in preparation) also found how the presence of three-spined stickleback in a lake had a greater effect on the trophic position of fish than the structure of the lake habitat.
GENERAL DISCUSSION AND CONCLUSIONS
Many studies have attempted to understand the presence and bioaccumulation of OHCs in the Arctic, mostly using pollution levels and their spatial/temporal trends that together provide a comprehensive picture of the pollution pattern in Greenland (Cleemann et al., 2000; Malmquist et al. , 2003) and the Arctic (AMAP Muir et al., 1995). Finally, the temporal trends of PBDE were consistent in the nuclei to the surface, neither increasing nor decreasing. Essentially, despite the ban of some OHCs, they were found to still be present in the Arctic freshwater sediments.
Their population can reach tens of thousands of individuals along the coast of Greenland in the North Water Polynya (González-Bergonzoni et al., 2017). Concentrations of heavier PCBs, whose concentrations were higher in NOW5 compared to the other lakes, indicated an increase of higher molecular weight pollutants to food tissues, which are difficult to metabolize and further accumulate in the lake's food tissues, creating "hot-spots" ” of pollutants in the Arctic lakes (Evenset, Carroll, et al., 2007). Given that freshwater species such as mountain trout constitute an important part of the diet of indigenous peoples, and high levels of POPs were found in indigenous populations, it is imperative to study these fish as well (AMAP, 2015; Carlsson et al., 2018; Lakhmanov et al ., 2020).
Furthermore, climate change may also exacerbate the re-emission of OHCs from ice, sediments and soils, increasing the mobilization of these pollutants in Arctic abiotic compartments and may concentrate in freshwater organisms (Ma et al., 2011 ). The presence of these OHCs in the Arctic is extremely concerning given that it is also one of the places most affected by increased warming due to climate change (Ma et al., 2016), especially because both stressors (climate change and OHCs) depend on temperatures (Macdonald, 2005; Macdonald et al., 2003). Climate change may also intensify the re-emission of POPs which have long been deposited in different environmental compartments (sediments, soil, glaciers) in the cold Arctic climate.
These differences testify to a selective effect in seabird accumulation and transport of the organohalogen to distant sites. Temperature and local effects best explained the patterns of accumulation of PCBs, DDTs and PBDEs in the Arctic trout, indicating the long-distance transport of the OHCs to the remote environments of Greenland.
Legacy and Emerging Persistent Organic Pollutants (POPs) in Terrestrial Spaces in the High Arctic: Sorption and Secondary Sources. Seabird guano is an effective transporter of persistent organic pollutants (POPs) to Arctic lake ecosystems. Atmospheric monitoring of organic pollutants in the Arctic under the Arctic Monitoring and Assessment Program (AMAP.
Temporal trends in persistent organic pollutants (POPs) in arctic air: 20 years of monitoring under the Arctic Monitoring and Assessment Program (AMAP). Persistent organic pollutants (POPs) in fish consumed by indigenous peoples of the Nenec Autonomous District. How global climate change will affect risks from long-range transport of persistent organic pollutants.
Monitoring persistent organic pollutants in polar regions: knowledge gaps and redundancies through evidence mapping. Legacy and Emerging Persistent Organic Pollutant Trends in the Circumpolar Arctic: Summary, Conclusions, and Recommendations. Past, present and future controls on persistent organic pollutant levels in the global environment.
Levels and trends of persistent organic pollutants in ringed seals (Phoca hispida) from central west Greenland, with a particular focus on polybrominated diphenyl ethers (PBDEs). Environmental fate and behavior of persistent organic pollutants in Shergyla Mountain, southeast of China's Tibetan Plateau.
ANNEX
Supporting Material
Values represent the sum of congener concentrations analyzed for each group of compounds. None of the random values were significant and were therefore excluded from the final models. None of the random slopes and intercepts in the models were significant, so they were excluded from the final structure.
The airport was scaled from 0-3 depending on the size and use of the airport; 0 no airport present, 1- airport with one runway (< 900 m) and small number of passengers, 2- airport with runway (> 900 m) and higher number of passengers than 1, 3- with the largest airport (longer runways) , > 2500 m) and highest number of passengers.
Supporting Material
The sediment fluxes of PCBs, HCHs, drins, chlordanes, PBDEs, HCB and endosulfans were highest in the upper sediment layer of the polynyamer (year 2014). 15–16ng/g; Tables 2–3), the concentrations of all POPs from the core of the lake with strong avian influence, NOW5, are lower than those reported in the lake cores of remote high mountains of Europe (Grimalt et al., 2004a). Phytoplankton in the water column is a transport engine of organohalogen compounds to the sediments, both in lacustrine (Meijer et al., 2006) and in marine environments (Dachs et al., 2002).
In lacustrine environments, sedimentation fluxes of organohalogen compounds driven by sinking phytoplankton in the water column have been related to water column chlorophyll concentrations by Eq. (1) (Meijer et al., 2006). Similar downward trends were recorded in Lake Ellasjøen where the maximum concentration was observed in the 1966 core section (Evenset et al., 2007b). However, on Devon Island, concentrations of these pollutants in sediment cores of lakes with strong avian influence (Cape Vera) show higher concentrations in the most recent sections of the core (Michelutti et al., 2009a, 2009b).
Most of the studies focused exclusively on dieldrin, but in the current study all three were drins. For example, in one study of freshwater lakes from Alaska, it was detected at concentrations of 0.17 ng/g dw in the upper 2 cm of the sediment cores (Allen-Gil et al., 1997). Temperature dependence of the distribution of organochlorine compounds in the mosses of the Andes Mountains.
Influence of diet on accumulation of organochlorine compounds in herons breeding in remote riverine environments. Past, present and future controls on levels of persistent organic pollutants in the global environment.
