Risikovurdering av beitedyr i Melbu skyte- og øvingsfelt – jordspising, beiteadferd og metallopptak

The Norwegian military shooting ranges contain metal contamination, such a lead and copper, from ammunition residues. These shooting ranges are usually not fenced, and can therefore be part of ruminants’ rangeland pasture. In 2017 a study was conducted on Melbu shooting range in Hadsel, to get more knowledge about the risk for ruminants’ grazing on shooting ranges. Parameters such as the grazing behavior, soil ingestion rate and accumulation of metals in plants were studied. Samples were also collected from three additional locations: Hengsvann and Steinsjøen shooting ranges, and a cultivated pasture in Kjeller. Eight wildlife cameras were installed in Melbu shooting range, taking pictures when the ruminants moved in front of them. GPS trackers were also attached to some of the sheep. Grass and feces samples were collected three times during the grazing period in Melbu, and soil samples were collected once in the same areas. Blood samples were collected from lambs and calves before and after the grazing period. In addition, liver samples from lambs were collected during slaughter. In the three additional locations, soil, grass and feces samples were collected once. It seemed as if the ruminants were not attracted to the heavily contaminated areas, but they did not shy away from them either. The animals generally grazed very little in areas with marsh terrain. The most heavily grazed area was the grass area on range 3/4, which had very little contamination. Varying degree of pollution was found in Melbu. The lead contamination in five places was classified as “very bad”, while the copper concentration was classified as “bad” in a couple of areas. In the remaining areas the copper and lead concentration was characterized as “moderate”, “good” or “very good”. The lead concentration in grass had a positive correlation with the lead concentration in soil, while no correlation was found between the copper concentration in soil and grass. Elevated concentrations of copper and lead were found in the liver of some lambs, but none had copper or lead concentrations consistent with poisoning. The average concentration of copper and lead in lamb and calf blood did not exceed normal values either before or after the grazing period. 12 of the lambs did have copper concentration above normal in the blood, but all of these were measured before they had grazed on the shooting range. None of the animals had elevated concentration of lead in the blood. The soil ingestion rate found was very low; all under two percent and most under 1 percent. Because some of the copper and lead concentrations in grass were high, and the soil ingestion was very low, most of the copper and lead ingested by the ruminants came from grass. None of the calculated doses of ingested copper and lead exceeded the daily ingested value considered toxic for sheep and cattle. An overall evaluation based on the results from this study shows that there is minimal risk of metal pollution for ruminants grazing on shooting ranges, even on the heavily contaminated sites. This is mainly due to four factors: the soil ingestion rate was low, the ruminants were not attracted to the contaminated areas, the accumulation of metals in grass was low and the heavily contaminated areas were limited.