Search

Within the Swedish National Monitoring Programme for Contaminants in Freshwater Biota, perch, pike and Arctic char are being analysed from 32 lakes distributed all over Sweden. One of the main objectives of the monitoring has been to detect temporal trends in different areas and for different contaminants. However, the measured concentrations in biota can be affected by biological factors such as age, length, trophic position (TP), fat or dry weight content. A change in one or several of these variables over time, or even among specimens taken within the same year, is likely to result in an increased variation of the measured concentrations and hence in a lower chance of detecting a trend. The purpose of this study was to evaluate if an adjustment of contaminant time trends by primarily stable isotopes, but also other confounding factors can: A) reduce the individual and between-year variation and hence B) improve the likelihood of detecting temporal trends in time series for metals and organic contaminants. The study revealed an improvement in the likelihood of detecting a contaminant trend after adjustment of the data for almost all lakes and for all tested substances. For some lakes and substances, this improvement was substantial. Age seems to be an important confounding factor for metals and per- and polyfluoroalkyl substances. For lipophilic substances, fat content also appears to be an important factor in some lakes together with adjustments for carbon and nitrogen isotope ratios (d13C and d15N), which all reduced the variation in contaminant data. This suggests that there is a benefit of adjusting data on a regular basis in contaminant monitoring programmes in the future.

The report summarises the monitoring activities within the National Swedish Contaminant Programme for freshwater biota. Each monitored contaminant has been examined in pike, perch or Arctic char from 32 lakes from the north to the south in Sweden. No general trend could be seen for mercury, and all samples were above the EU threshold. Lead was generally decreasing. Cadmium concentrations showed no consistent trends over the monitored period, and cadmium concentrations in 2017 were below the suggested threshold in all lakes. Nickel showed a general upward trend in 30% of the perch lakes. Arsenic concentrations showed no general spatial pattern and were increasing in liver from Arctic char, pike and perch from approximately 50 % of the sampling sites. Tin concentrations decreased in the majority of the perch time series during the most recent ten years. For copper, no general spatial pattern existed for concentrations in perch and about one third of the monitored lakes showed an upward trend. No general trend was observed for silver and aluminum. In general, downward trends were seen for; PCBs, HCHs, DDT, DDE and PCDD/Fs in all species (with a few exceptions). The chlorinated compounds generally showed a somewhat higher concentration in the southern parts of Sweden. Most chlorinated compounds were below the suggested target levels. No general trend was seen during the monitoring period for PBDEs. However an indication of decreasing concentrations of PBDEs is seen in the most recent years. The concentration of HBCDD was under LOQ in a majority of the samples. Several of the perfluorinated carboxylic compounds showed an increase in concentration in arctic char, while PFOS and FOSA decreased. In perch PFOS has decreased since 1995. Higher concentrations of perfluorinated compounds can in general be seen in the southern part of Sweden. In all lakes, PFOS is below the target level for all species.

The report summarises the monitoring activities within the National Swedish Contaminant Programme in marine biota. In this report, we present time series and maps of most contaminants in various species but we only comment results that shows large differences compared to the previous year. Results show that herring from Holmöarna had elevated concentrations during the last two years of the time series for approximately half of the analysed metals, most chlorinated pesticides, polychlorinated biphenyls (PCBs) and brominated flame retardants (BFRs). The last two years’ Herring is on average one year older than the previous years’, heavier and the last years’ fat percentage is ca. 2 % higher compared to the year before. These differences in biological variables may have had an influence on the elevated contaminant concentrations. Also, herring from Väderöarna shows increasing concentrations for several chlorinated pesticides, PCBs, dioxins, and BFRs during the ten most recent years. A reason for this might be that the included fish were older during the seven most recent years, although their size was similar or smaller than previous years. Additionally, the fat percentage of the tissue has also decreased over time and might influence the results. This year’s report is also the first to show PFAS concentrations in Cod, Perch and Eelpout where Perch has the highest concentrations of most PFASs within the Baltic Proper sampling sites. This report is also the first report within the Swedish National Monitoring Programme of Contaminants in marine biota presenting environmental contaminant data in eggs of Common tern and Eurasian oystercatcher. In general, many of the compounds could be detected in Common tern and Eurasian oystercatcher. Concentrations of several of the contaminants are similar in the two species, but there are exceptions among each contaminant class and even opposing time trends for some contaminants. There are clear differences in contaminant concentrations between species for PCDD/Fs and BFRs; for most PCDD/Fs, concentrations are higher in Eurasian oystercatcher compared to Common tern, while for the BFRs concentrations are higher in Common tern, with the exception of HBCDD.