Last updated 17 August 2016

The glaucous gull (Larus hyperboreus) is at the top of the food chain and exposed to excessively high amounts of persistent organic pollutants. It is the most abundant of the large gulls in the Arctic, and its important food items are benthic fauna, fish, carrion, and eggs and chicks of other seabirds.

Pollutants in glaucous gulls
Photo: Stein Ø. Nilsen / Norwegian Polar Institute

What is being monitored?

Persistent organic pollutants (POPs) in glaucous gull

Most organic legacy pollutants, like PCB-153 and oxychlordane, have declined in recent years because the international regulation of their use has been effective. For others, such as DDE and HCB, the variation between years is too large to see any effect. Chlordane shows a tendency to decrease.
(Cite these data: Norwegian Polar Institute (2022). Organic pollution in glaucous gull blood plasma. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL:

The concentration of PFOS in glaucous gull eggs from Bjørnøya decreased by 27.6% from 2011 to 2013 while the reduction in eggs sampled from Kongsfjorden was 18.7%. The reason for the considerable difference in PFOS concentration between eggs sampled from Bjørnøya and Kongsfjorden is currently unknown.
(Cite these data: Norwegian Polar Institute (2022). PFOS in glaucous gulls eggs, wet weight. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL:

The concentration of PFOA in glaucous gull eggs from Bjørnøya was reduced by 11.3% from 2011 to 2013. There was a 43.6% decrease in PFOA levels from 2012 to 2013 for eggs sampled in Kongsfjorden.
(Cite these data: Norwegian Polar Institute (2022). PFOA in glaucous gulls eggs, wet weight. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL:

Details on these data

Last updated17 August 2016
Update intervalAt least every second year
Commissioning organizationMinistry of Climate and Environment
Executive organizationNorwegian Polar Institute
Contact personsGeir Wing Gabrielsen


Individual blood samples from glaucous gulls are analysed. The blood is centrifuged and the light-coloured part (the blood plasma) is analysed for pollutants.

The glaucous gull is listed as Near Threatened on the Svalbard Red List. Consequently, it has been decided to use blood samples for the monitoring rather than killing the birds in order to obtain tissue samples. The samples are taken in connection with other fieldwork activities by the Norwegian Polar Institute.

The samples are processed in the laboratory using various techniques so that several groups of pollutants can be analysed. The following is done to analyse for organic, fat-soluble pesticides, PCBs and some brominated flame retardants (BFRs):

  • 1ml of plasma is weighed and an internal standard for pesticides, PCBs and BFRs is added.
  • 2ml superclean (milliQ) water saturated with ammonium sulphate and 2ml of ethanol are added, and the solution is vigorously mixed using a vortex.
  • Pollutants, fat and proteins are then extracted from the mixture twice using 6ml of n-hexane as the solvent.
  • The extract is concentrated to 200 μl by vacuum evaporation (RapidVap).
  • It is further cleansed with activated Florisil (magnesium silica) in a RapidTrace SPE machine.

The samples are analysed in an interlinked gas chromatograph – mass spectrometer (GC-MS). The sample is injected and separated on a 30-metre column. The initial temperature is 60–70 °C, and this is raised incrementally using pre-determined programmes depending on which substances are being analysed. Helium is used as the carrier gas in the machine.

The concentrations of the pollutants are calculated by quantifying internal standards with known concentration and comparing these with the response (chromatogram) from the samples.

For PFAS the procedure is as follows:

  • The samples are extracted twice from homogenized eggs with acetonitrile in an ultrasonic bath. The concentrate is cleaned using activated charcoal and ethanoic acid. Then ammoniumacetate is added and the concentrate is precipitated.
  • High performance liquid chromatography coupled to high resolution mass spectrometry (HPLC-HRMS) and tandem mass spectrometry (MS/MS) are used in the instrumental analyses of PFASs.
  • Internal standards, analysis of duplicates and reference materials form the quality control.

Since the data are only collected every 3rd year, the analysis will fail to give information on the variation in pollutant concentrations from year to year. When analysing time series, allowance must therefore be made for the possibility that year-to-year variations are not being detected. It will also take a long time to demonstrate changes in the time series since it is difficult to determine whether a difference between two measured points is due to an actual change or a random variation.

The lower Level of Detection (LOD) is calculated for each sample and is usually better than 0.1 ng/g. For PCB-153 and DDE, this is approximately 1000 times lower than the measured value in the sample. For oxychlordane, this is approximately 500 times lower than the measured value in the sample. For HCB, this is approximately 20 times lower than the measured value in the sample. The uncertainty is around 25–30%. Particularly LOD, but also the measurement uncertainty, has improved in recent years. In time series, there will therefore always be greater uncertainty attached to older measurements in the series.


The analysis is quality assured in accordance with the methods described in the accreditation. To avoid sample contamination, only superclean equipment is used in the laboratory. A blank and a standard reference sample are analysed for every 10th sample. The laboratory regularly takes part in international proficiency testing schemes.

Other metadata

The Norwegian Polar Institute’s data service

Reference level and action level

As POPs are manufactured pollutants that are not found in a natural state, the reference value for an unaffected state will be zero (really the detection limit).

Threshold limits

As the glaucous gull is a protected species, it is not used as human food. Hence, no limits have been set for the content of PCB or other pollutants in glaucous gulls. However, dietary advice has been given regarding gull’s eggs in Norway. This will also apply to glaucous gull eggs. The advice is to limit their consumption, and children and women of fertile age should not eat gull’s eggs.

Stringent measures have been applied to limit the spread of persistent organic pollutants. The Stockholm Convention regulates an international ban on the manufacture and use of PCBs and most western nations introduced strict regulations of PCBs around 1980. Furthermore, the Stockholm Convention regulates an international ban on the manufacture and use of DDT, which is the parent compound of DDE, and most western nations introduced strict regulations of DDT at the end of the 1960s and the beginning of the 1970s. The Stockholm Convention also regulates an international ban on the manufacture and use of chlordanes and most western countries introduced strict regulations of chlordanes in 1970–1990. Chlordanes have been little used in Europe.The Stockholm Convention regulates an international ban on the manufacture and use of HCB as a fungicide and verifies that the chemical industry has reduced its emissions.

Status and trend

The levels of organic pesticides like HCB and oxychlordane have dropped during the 18 years the glaucous gulls have been monitored. However, there are substantial variations from year to year. These variations mean that it is too early to draw any final conclusions regarding the trends, but since the trends coincide with the ban on the use and discharge of the pollutants, it is most likely that the average reduction is real.

The concentration of DDE, the breakdown product of the insecticide DDT, also varies considerably from year to year. It is not possible to say whether the DDE levels in glaucous gulls are rising or falling. This is actually surprising because the use of DDT was banned in most western countries already in the 1970s. However, some DDT is still being used to combat the malaria mosquito in southern parts of Africa following a recommendation from the World Health Organisation (WHO), but it is uncertain whether any of this can be found in the Arctic. Another possible reason may be that the levels had already declined before the measurements began and the speed of the reduction has flattened out. The proportion of DDE is still high compared with the other pollutants known to be present in glaucous gulls.

The PCB level is presented in MOSJ as the concentration of PCB-153, the most stable variant of the 209 possible PCBs. There is a very good link between PCB-153 and the other PCBs. The concentration of PCB-153 therefore gives a correct picture of the development of the PCB levels in the glaucous gull.

There was some variation in the concentration of PCB-153 during 1997–2009, but on the whole the levels halved during this period due to the regulations that were introduced. New uses for PCB were banned in most western countries in the early 1980s. Many countries also put an emphasis on proper waste handling and disposal when dealing with PCB in rubbish during the phasing-out period, which was probably important since very large quantities of PCB were used in many products.

PFASs (PFOS and PFOA) have been produced since the 1950s due to their desirable physico-chemical properties, but it is only relatively recently that they have become the focus of scientific investigation. After PFOS was detected in wildlife, its main producer initiated a voluntary phase-out in 2001. The reduction seen here is thus likely a continuation of a longer time period of decreasing levels of PFOS in wildlife. PFOA has been proposed for inclusion in the Stockholm Convention and is therefore an important contaminant to focus on. The data herein show a reduction of both PFOS and PFOA levels in glaucous gull eggs from Bjørnøya and Kongsfjorden. There is a considerable difference in PFOS concentrations between eggs from Bjørnøya and Kongsfjorden and the specific reason for this is currently unknown. However, glaucous gulls from Bjørnøya are likely exposed to higher concentration of PFASs through their diet which is then transferred into the eggs.

Causal factors

The high levels of “old” organic pollutants like PCB-153, DDE, oxychlordane and HCB, and at times high values of “new” pollutants like  perfluoroalkyl and polyfluoroalkyl substances (PFOS and PFOA) are mainly caused by 2 factors:

  1. The glaucous gull is at the top of the food chain. These pollutants are stable and are slowly broken down in nature. The pollutants entering the food chain therefore become more concentrated as the animals eat (bioaccumulation). When these animals are eaten by the next ones in the food chain, further accumulation takes place. Hence, the levels of stable pollutants increase up the food chain. The difference in the concentration at each level in the chain varies considerably from one pollutant to another, and in the food chain in the Barents Sea it is from around one to more than 2000. This is due to the physico-chemical properties of the compounds.
  2. Glaucous gulls have limited ability to convert and rid themselves of them through their faeces.


The high levels of pollutants recorded in glaucous gulls from 1997 to 2013 have had considerable consequences for the health of the glaucous gulls on Bjørnøya in the Barents Sea.

Some of these glaucous gulls eat large numbers of seabirds, eggs and chicks during the breeding period and these individuals are particularly likely to have the highest levels of pollutants. The most pronounced effects have been found in these birds, but negative effects have also been seen in birds away from Bjørnøya.

Effects have been found on the enzyme, immune and hormone systems, reproduction and survival. The significance of these effects is, nevertheless, still uncertain, but as so many negative effects have been found in the same population there is little reason to assume that this does not have a negative impact on the health of the glaucous gulls. Modelling has also shown that pollutants probably have negative effects on the glaucous gull population on Bjørnøya.

Glaucous gulls which have been found sick, dying and dead on Bjørnøya have had extremely high levels of pollutants.

There are probably several natural causes for the death of glaucous gulls at their breeding sites, including old age. However, studies show that the ability to find food may be reduced with increasing concentrations of pollutants. This means that individuals with a high level of pollutants may starve and thus decline in weight. A drop in weight means that fat is consumed which, in turn, raises the concentration of pollutants since they are in the fat. Consequently, pollutants may contribute to a negative “spiral effect”, whereby poor availability of food gives increased pollutant concentrations which, in turn, make the individual less able to find food, ultimately resulting in it dying due to shortage of food and poisoning.

As the glaucous gull is a top predator in the arctic system and is exposed to high levels of pollutants, it is important to follow the trend in pollutant concentrations over time to assess the health of the glaucous gulls and verify that the international regulations concerning pollutants are working.

Samples from glaucous gulls are also often used to seek possible new pollutants.

About the monitoring

The glaucous gull is the most important, large gull in the Arctic. It has a circumpolar distribution, which means that it lives in arctic areas in Russia, Alaska, Canada, Greenland and Svalbard. The glaucous gull migrates southwards in winter, but not out of the Arctic. The majority of glaucous gulls from Svalbard migrate to the waters off Iceland and the southern tip of Greenland in winter. In summer, glaucous gulls are found in the northern part of the Barents Sea, from Bjørnøya in the south to Franz Josef land in the northeast.

Knowledge about pollutant levels in glaucous gulls provides knowledge about how pollutants become increasingly concentrated up the food chain and on possible effects in the top predators. The substances included in the monitoring are organic pollutants that are found everywhere in the environment even though many are no longer in use.

Research on glaucous gulls has uncovered effects of pollutants on the behaviour and the immune, enzyme, hormone and vitamin systems of the gulls. Individuals with the highest levels of pollutants have impaired reproductive ability and the survival of adults is lower. A general decline in the levels of phased-out pollutants is therefore positive for the glaucous gulls and the environment. Research to reveal whether known effects disappear with the decline of the “old” pollutants remains to be performed.

Places and areas

Relations to other monitoring

Monitoring programme

  • The Norwegian Polar Institute monitoring programme

International environmental agreements

Voluntary international cooperation

  • None

Related monitoring

  • None

Further reading



  1. Bogan, J.A. and Bourne, W.R.P. 1972. Organochlorine levels in Atlantic seabirds. Nature 240: 358.
  2. Bustnes, J.O. 2006. Pinpointing potential causative agents in mixtures of persistent organic pollutants in observational field studies: A review of glaucous gull studies. Journal of Toxicology and Environmental Health – Part A 69: 97–108.
  3. Bustnes, J.O., Gabrielsen, G.W. and Verreault, J. 2010. Climate Variability and Temporal Trends of Persistent Organic Pollutants in the Arctic: A Study of Glaucous Gulls. Environmental Science & Technology 44 (8): 3155–3161.
  4. Gabrielsen,G.W. & Sydnes, L. K. 2009. Pollution in the Barents Sea. (eds E.Sakshaug, G.M.Johnsen & K.M.Kovacs) Ecosystem Barents Sea, Tapir Academic Press, Trondheim.
  5. Verreault, J., Gabrielsen, G.W. & Bustnes, J.O. 2010. The Svalbard Glaucous Gull as Bioindicator Species in the European Arctic: Insight from 35 Years of Contaminants Research. Reviews of Environmental Contamination and Toxicology 205, Springer Science, 77-116.