Heavy metals have been part of the Norwegian national monitoring program since 1980. Monitoring heavy metals in air was initiated at Zeppelin Observatory in 1994 and at Andøya Observatory in 2010. In 2013, annual mean concentrations of most heavy metals except mercury, nickel, and vanadium were somewhat higher at Zeppelin than observed at Andøya. This was due to individual episodes with high concentrations of heavy metals at Zeppelin during winter in 2013 (Figure 4.4.12).
Heavy metals in air
Episodes with increasing levels of cadmium and lead are well correlated. High levels of cadmium and lead occurred at the same time, and were not necessarily a result of common emission sources. Polluted air is often well mixed, and high levels can occur when meteorological conditions favor long-range transport. At Zeppelin, there have been significant reductions since 1994 for several elements, including arsenic, cadmium, copper, lead, nickel, and vanadium. Reductions in lead and cadmium have been 44% and 49%, respectively. Reductions of lead in the atmosphere are measured in the whole Arctic as a result of a ban on the use of leaded gasoline (AMAP 2004). No significant trends were found for mercury at any of the sites within their measurement periods. Gaseous mercury has a longer residence time in the atmosphere than the particulate bound heavy metals, and therefore has larger potential to be transported far from emissions sources. As a consequence, mercury is a global pollutant while the other heavy metals originate more from regional pollution emissions.
Riverine inputs of heavy metals to the Barents Sea
Results from monitoring with passive gear to estimate riverine input of heavy metals into the Barents Sea basin indicate that copper, nickel, and sulphates are the main pollutants from Norwegian and Russian river tributaries (Figure 4.4.13). Highest concentrations were found in the Kolosjoki River, and levels were related to the direct discharge of wastewater from iron smelting operations conducted upstream. Relatively high concentrations of chromium, lead, and zinc were recorded in the Pinega River in the Arkhangelsk area (Kaste et al., 2014). Levels of nickel and copper in the rivers examined have increased throughout the 2000s. Nickel concentrations have increased in all rivers, and copper concentrations have increased in Pechanga River. In Norwegian rivers far north, the highest levels of nickel and copper were found in Pasvik River and Jakobselva River. Highest levels of chromium were found in the Mattusjåkka-, Storelva-, and Jakobselva- rivers. Highest concentrations of Zn were found in Tana River and Neiden River. Highest concentrations of Pb were found in the rivers Stabburselva, Adamselva, and Jakobselva (Skarbøvik et al., 2012).
Figure 4.4.13. Results from monitoring by passive samplers in the three rivers Pasvik, Pinega and Kolosjoki. High levels of heavy metals found in river Kolosjoki are related to wastewater discharge from smelters (Kaste et al., 2014).
Heavy metals in bottom sediments
Spatial distribution of lead, copper, cadmium, nickel, chromium, iron, manganese, and zinc in sediments is characterized by a general trend of increasing concentrations from coastal areas to the deep-water part of the Central Trough (Figure 4.4.14, Table 4.4.6). Kola Bay is a high anomaly zone for heavy metal contamination.
Table 4.4.6. Concentration of heavy metals and trace elements in Barents Sea sediments, µg/g dry weight.
Pechora Sea sediments typically have a lower level of heavy metal and trace element accumulation than other areas in the Barents Region (Figure 4.4.14a,b). Generally a relatively low concentration of heavy metals and trace elements is typical for bottom sediments of the Barents Sea.
Geochemical estimates of sediment concentrations during 2014 in the Russian zone were made using 2008-2012 monitoring data (Figure 4.4.15). Indications were that for near-shore areas high anomalies of heavy metal contamination were influenced by water transport within the currents.
Current levels of contamination in sediments from technogenic radionuclides (Cs= Cesium, Sr=Strontium, Pu=Plutonium, Sb=Antimony) are very low (Figure 4.4.16). MMBI data for 2001-2011 show that the level of 137Cs ranges from 1 to 3 Bk/kg (becquerel per kilogram), and the level of 90Sr ranges from 0.2 to 2.0 Bk/kg. However, in the deeper sediments of the central Barents Sea 137Cs ranges from 5–8 Bk/kg and 239,240Pu ranges from 0.004 to 1.33 Bk/kg. Episodically, the level of 125Sb was detected at 0.4 Bk/kg in near shore areas in association with waters being transferred with the currents from industrial plants in England.
In Kola Bay, the level of 137Cs in sediment is about 10 Bk/kg (on average) with a maximum value of 21.5 Bk/kg in the northern part.