The highest levels of long-range heavy metal pollution are found in the southern half of Norway. There has been a marked drop in concentrations of heavy metals in moss since the first nationwide survey in 1977. The latest survey was completed in 2005, and the results show that concentrations of most heavy metals are still decreasing.

The Climate and Pollution Agency is conducting a new survey of heavy metals in moss in 2010 - 2011.

Background levels show natural concentrations

Moss always contains a certain amount of all naturally occurring elements. The natural concentrations are called the background levels. Background levels for lead and cadmium have been determined to be 5 micrograms per gram and 0.1 micrograms per gram respectively. However, the true background level for lead is probably considerably lower than 5 micrograms per gram.

If the concentrations of heavy metals measured in moss exceed the background levels, we interpret this as being a result of anthropogenic emissions.

Deposition of heavy metals carried to the southernmost parts of Norway with long-range air pollution results in higher concentrations of metals in plants and herbivorous animals. This relationship is particularly clear for lead. A correlation has been shown between lead concentrations in the moss Hylocomium spendens and in the liver of willow grouse, black grouse and mountain hare. However, the lead concentrations that have been measured are far below the levels at which harmful effects have been demonstrated.

Between 1977 and 1990, deposition of arsenic, cadmium, lead, zinc and vanadium was reduced by more than 50 per cent. This was a result of measures introduced to control emissions, a changeover to less polluting energy sources, and the closure of many factories and plants in Eastern Europe.

In 1995, the drop in deposition rates appeared to have come to a stop for most metals, but the 2000 survey showed a continued reduction. From 2000 to 2005, there was a reduction in the deposition of most heavy metals, with the exception of mercury. Lead deposition in Southern Norway is now only 10 per cent of the level in 1977.

Due to a reduction in long-range input, Norwegian sources subsequently mean more for the deposition of heavy metals locally in Norway. Smelters on the Kola Peninsula are however still responsible for substantial deposition of nickel and copper in eastern parts of Finnmark, and in addition to smaller amounts of arsenic and cobalt.

A survey of seven industrial sites in Norway showed elevated concentrations of heavy metals in their surroundings. For example, chromium deposition is considerably elevated around a ferro-chromium plant in Mo i Rana in Nordland. Other towns where deposition of pollutants from local sources has been registered are Odda, Årdal and Kristiansand. Chromium, copper and nickel deposition, and to some extent iron and mercury deposition, originates mainly from local point sources.

Local sources also contribute

Atmospheric long-range transport from other countries in Europe is the dominant source of arsenic, cadmium, lead, zinc and vanadium deposited in Norway. Long-range inputs have been greatly reduced since the first nationwide survey based on studies of moss was carried out in 1977.

The Convention on Long-Range Transboundary Air Pollution was signed in 1979. Since then, several binding protocols have been adopted under the convention. One of these is the Aarhus Protocol on Heavy Metals, which entered into force on 29 December 2003. Parties have undertaken to reduce their emissions of lead, cadmium and mercury below their levels in 1990, and are required to take the following steps:

• reduce the content of metals in products 
• introduce limit values for emissions from industrial sources
• phase out the use of leaded petrol.

Norway meets the requirements of this protocol.

Emissions of several heavy metals to be reduced or phased out

The environmental authorities have drawn up a priority list of substances that represent a serious health or environmental risk in Norway. The list includes the heavy metals arsenic, lead, cadmium, copper, chromium and mercury. Norway’s goal is to reduce emissions of these substance substantially, at the latest by 2010.

Industrial enterprises taking part in the moss surveys

The Climate and Pollution Agency wishes to gain a better overview of the effects of environmentally hazardous industrial pollutants on the local environment around industrial sites. The nationwide surveys of heavy metals in moss have therefore been extended to include ten industrial plants. Extra samples of mosses have been taken near these plants to evaluate the local inputs of heavy metals.