Atmospheric transport of pollutants to the Barents Sea

Last updated 23 February 2022

The transport of environmental pollutants to the Barents Sea occurs primarily by means of air and ocean currents, but inflows from rivers, run-off from land and transport by ice also contribute.

Status and trend

In 2018, the concentrations of PCBs, PAHs and most pesticides measured in the air at Zeppelin were slightly lower than in previous years. There has been a continued downward trend. The levels of brominated flame retardants (PBDE) vary from year to year, and no clear trends are discernible. PFASs and HBCD are mainly below the analytical detection level, in other words, below the concentration at which the compound can be measured, and no clear trends can be discerned.

Levels of the pesticide HCB showed an increasing trend from the early 2000s to 2015, but then exhibited a downward trend in 2016-2018. The annual mean concentration of HCB at Zeppelin in 2018 (63 pg/m3) is the lowest that has been measured since 2003.

The annual mean concentration of atmospheric PAHs showed a clear downward trend from 1998 to 2006. Since then, the levels have been relatively stable, with some annual variations. Elevated levels in 2013 and 2014 are mainly due to individual episodes of high levels. Since then (2015-2018), the levels have declined.

The long-term trend for atmospheric PCBs at the Zeppelin Observatory is for levels to have decreased, but there are also variations from year to year.

Most of the PFAS compounds measured in Svalbard are below the analytical detection level. In other words, the levels are so low that they are not measurable. PFOS, PFOSA and PFOA are the compounds that are measured above the detection level more than any others. The concentrations vary from year to year and no clear trend can be discerned.

There has been a slight decrease in atmospheric mercury levels in Svalbard since 2000. This tallies with observations at lower latitudes. However, at lower latitudes, the decline has been clearer.

The concentration of lead has fallen by 30 percent at the Zeppelin Observatory since measurements began in 1994. Lower lead levels correlate with significantly reduced emissions in Europe and North America, following the banning of lead in petrol in Western countries. However, emissions in Asia have increased sharply.

The level of mercury measured in the air in Svalbard varies throughout the year. In winter, contaminated air is transported from western, central and eastern regions of Europe northwards, resulting in higher levels of atmospheric mercury in Svalbard. The levels are also high in summer. This is due to the evaporation of mercury from the ocean, as a result of the sea ice melting.

In the spring, there are periods when atmospheric mercury levels are greatly reduced. This is due to processes in the atmosphere that convert mercury into more reactive compounds that are deposited on the ground, the ice or the ocean surface. The majority of the mercury will evaporate back into the atmosphere.

A small proportion will end up in sediments, the soil, lakes and in the ocean. Algae and bacteria can convert mercury into highly toxic methylmercury, which is how the mercury enters the food chain. Methylmercury is bioaccumulated through the food chain. Fish and mammals high up in the food chain may have high concentrations of methylmercury in their bodies through their food intake.

Causal factors

The concentrations of airborne pollutants in Svalbard are affected by emissions of pollutants in different parts of the world, with Europe and Asia making the greatest contributions. The concentrations are also affected by climatic conditions that impact the atmospheric modes of transport.

Consequences

Climate change with increased temperatures is expected to cause intensified dispersal of pollutants globally. The melting of sea ice and thawing of permafrost may cause the remobilisation and evaporation of pollutants into the atmosphere in the Arctic. Large forest fires and cropland burning have been shown to increase the transport of organic pollutants to the Arctic. Increased local industrialisation (such as oil and gas activities and mining) and shipping in the High North may contribute to increased transport of some of the pollutants measured in the air in Svalbard.

The transport and levels of many of the pollutants measured in the air in Svalbard have continued to fall, but for some pollutants there have been slight increases in recent years. Causes are assumed to be continued use of environmental pollutants in different parts of the world, and pollutants being released from previous deposition in the environment by rising temperatures. The mercury levels remained unchanged for a long time, but have shown a decline since 2007.

About the monitoring

The indicator describes atmospheric transport of pollutants to the Barents Sea. The Zeppelin Observatory in Ny-Ålesund in Svalbard has long time series from the 1990s of transport of the following pollutants:

– heavy metals: mercury, lead, cadmium, copper, arsenic.
– organic compounds: PAHs (38 components), PCBs (32 components).
– pesticides: DDT (6 components), chlordane (4 components), HCHs (2 components) and HCB.
Since 2006, brominated flame retardants and PFASs have also been included: PBDEs (16 components), HBCD (3 components) and PFASs (13 components).

The monitoring is performed as part of the “Long-range transported pollutants in air and precipitation” programme under the Norwegian Environment Agency. The Norwegian Institute for Air Research (NILU) performs the monitoring and also contributes results from its own measurement programme.