Concentrations of elementary mercury (Hg) measured at the Zeppelin observatory is at the same level as the concentrations measured in the southern part of Norway. There are episodes during spring time where levels of elementary Hg in gaseous phase decreases (Figure 4.4.7). The reason for this decrease is that light from the polar sunrise starts a chemical prosess that transform Hg to more reactive components that becomes bioavailable. Such inter-annual trends have also been found at other sites in the Arctic (AMAP 2002).
For other heavy metals measured in air, there are a decreasing trend for nickel (Ni) and lead (Pb) wheras other components show no or only minor changes in concentrations since 1994 (Aas et al. 2008). Reductions of Pb in the atmosphere are measured in the whole Arctic as a result of a ban on the use of leaded gasoline (AMAP 2004).
Recent sediment samples collected throughout the open ocean revealed levels within the limits of natural background levels of the heavy metals Zn, Cr, Co, Pb, Cd, and Hg (Knies et al., 2006, PINRO, Green et al. 2008).
The levels of Cu are also generally low. There are high natural background levels of Cu on the Kola peninsula and on the Novaja Zemlja (see Figure 4.4.8). The concentration of Cu increases in the northern direction from Varanday towards Novaja Zemlja. This can be due to a change in type of deposits, or run off from rivers and underground waters from Novaja Zemlja. The maximum concentration of Cu is found in silty-pelitic sediments in the Murmansk Trough (146 - 150 p.p.m), opposite Kola Bay. Apparently, these concentration are of natural character, connected with the clay structure in the bottom sediments, but run-off from the Kola bay is also a possible contributor.
The concentrations of Ni in bottom sediments exceed the natural background level (30 g/g dw) at all the stations in the Kola Bay. The levels vary from 32 to 215 ppm, and exceeds the level of “considerable pollution” at several stations (SFT 1997). Nickel is the main metal in the metal-working industry at the Kola peninsula. Arsenic (As) is present in high concentrations in the Barents Sea area. In the western part of the Barents Sea, As has been found in concentrations corresponding to Class III, marked pollution level, according to the classification guidance from the Norwegian Pollution Control Authority. In the eastern part of the Barents Sea the levels were in Class II (moderate pollution level). Maximum concentrations of As were found in bottom sediments in the area from the south of Novozemelsky to the Pechora sea. The average level of As concentration in sediments at the Kola polygon were 52,8 p.p.m for 2005-2008, lower than in the Pechora sea. The highest concentration of As was located opposite the mouth of the Kola Bay. The As concentration in silty-pelitic deposits in the open part of the Barents Sea was near 50-60 p.p.m.
Increase of concentration of As in clay deposits of the South Novozemelsky Through can be connected with its input as at the expense of a removal from Southern island of Novaja Zemlja and at the expense of infiltration of underground waters on faults. Occurrence of increasing concentrations of arsenic in nearmouth parts of Kola bay can be connected with its inflow from the Kola bay. Occurrence of local concentration of arsenic around the Shtokmanovsky deposit probably reflects inflow of gasfluids from bedrock.
Elevated barium (Ba) concentrations were encountered in the Håkon Mosby mud volcano area at the continental margin and near the Snøhvit gas/condensate field. The latter might be due to emissions of barite (BaSO4) additive of drilling mud used during drilling operations in year 2000.
Analysed fillets of cod from the Barents Sea had concentrations of Cd, Hg or Pb below EUs limits for food consumption (Sunnanå 2009). The values were at about the same level all three years from 2006-2008. Concentrations of Ca and Pb were higher in cod liver than in fillet, while the Hg consentrations were higher in cod filet (> 0,1 mg Hg/kg). There are no marginal value from EU metals in fish liver (Figure 4.4.9).
Shrimp samples from 2007 and 2008 shows that the edible part of shrimps all had concentrations of metal below EUs limits for consumption. The levels of Cd were at the same level as analyses from 1995 and 2000. The concentrations of Cd and Pb were generally higher in whole shrimps than in analyses were only the edible part was included (see Sunnanå et al. 2009).
Low levels of heavy metals was also found in fish from the Russian side of the Barents Sea. Concentration of nickel, chromium, cobalt, lead, and cadmium in the muscles of all fish examined were below detectable limits. Concentrations of copper, zinc, and mercury varied within a very narrow range, and corresponded to natural background levels. Concentrations of cadmium in livers of all fish examined did not exceed the permissible level for consumption (0,7 µg/g ww). One exception was Atlantic wolfish where the concentration of cadmium in liver twice exceeded the standard. Concentrations of arsenic in individual samples from muscles of cod, long rough dab, wolffish, haddock and thorny skate exceeded the established standard of 5,0 µg/g ww.