Sandimirov S. Screening studies of POP levels in bottom sediments from selected lakes in the Paz watercourse / In State of the environment in the Norwegian, Finnish and Russian border area. The Finnish Environment. Finland, Jyvaskyla: Kopijyva Oy. 2007, №6.

Screening studies of PO P levels in bottom sediments from selected lakes in the Paz watercourse 5.4. Persistent Organic Pollutants (POPs) In science and daily language, POPs stands for persistent organic pollutants. In general, the term POPs does not have a clear definition and includes chemical compounds that are highly resistant to most forms o f degradation and, therefore, have relatively long half-lives. POPs are often chlorinated and characterised by low water solubility and high lipid solubility. Due to their affinity for lipids they can easily be transported throughout the food chain and bioaccumulate in the fatty tissues o f top-level predators, including humans. Most o f the POPs are semi-volative compounds, and they are distributed to different degrees between gaseous, particulate and aqueous phases in the atmosphere, thereby facilitating their long- range transport. Laboratory investigations and environmental impact studies have shown that POPs can cause birth defects, various cancers, immune system dysfunction, neurobehavioural effects and reproductive abnormalities in wildlife. Although the effects o f POPs on human health are still quite unclear, there is a growing concern that even low-dose, long-term exposure may cause significant adverse health effects. For more information see de March et al. (1998) and AMAP (2004). 5.4.1. Chlorinated pesticides Table 4 summarize the levels o f organochlorine pesticides found in sediments from lakes within the study area. Geographic distributions o f the selected OC concentrations are shown in Figure 6. DDD T was the dominating OC-pesticide in the sediment samples. The highest levels were measured close to the smelters (Figure 6). The levels o f IDDT detected in this study are high compared to levels measured in sediments from the Arctic and from Norway (AMAP 1994, Muir et al., 1995, Rognerud et al., 1997, Skotvold et al., 1997, Evenset et al., 2006). Skotvold et al. (1997) found concentrations between 0.1 and 3.8 ng/g dw in surface sediments from 15 lakes in Finnmark County in 1995 - 1996. In 8 Arctic lakes in Canada the levels varied from 0.1 to 10 ng/g dw (Muir et al., 1995). The levels o f p ,p '-DDE in Paz-watercourse is also high compared to levels measured by Skotvold et al. (1997). The reasons for the high levels o f p ,p '-DDT in both surface sediment and reference sediment from Stuorajavri Lake is not clear. Also for Hexachlorobenzene (HCB) and Chlordanes were the highest levels were measured close to the smelters. However, the levels o f these components were significantly lower than the DDT concentrations. HCH and endrin were only detected in samples from stations 4 and 5. Dieldrine and mirex were not detected in any o f the samples. In sediment samples from station 4 and 5, pentachlorobenzene, octachlorostyrene, aldrin, dachtal, PCPME and photomirex were analysed in addition to the listed OCs. Aldrin and photomirex were not detected in any samples. Concentrations o f the others above-listed OC compounds were low, ranging from 0.012 to 0.082 ng/g dw (Table 4). Rapport APN- 514.3665.01 14