Heavy water

 作者:邓掂     |      日期:2019-03-07 05:02:00
By Rob Edwards Drinking water in Kosovo could end up being contaminated with radioactive uranium at levels in breach of safety limits, warns the United Nations Environment Programme (UNEP). A new study by an international team of scientists says the water should be monitored and the uranium cleaned up. Over 30,000 shells containing nine tonnes of depleted uranium (DU) were fired by US A-10 aircraft at 112 sites in Kosovo during the conflict in 1999. The material is very dense and helps the shells penetrate armour. Because of controversy over how this might endanger the health of local people, 11 of the sites have been examined for UNEP by 14 scientists from the US and Europe. Their report, published on 13 March, concludes that there is “no widespread contamination” by DU and hence no significant risk to health. It points out, however, that the water from wells in heavily shelled areas could be polluted in years to come as the uranium dissolves and leaches into the groundwater. The report says a thousand DU shells buried in the ground could increase uranium levels in water by 100 times. This would push them over the two micrograms per litre limit recommended by the World Health Organisation. An A-10 fires up to 150 rounds in a single dive, which can penetrate seven metres into soft soil. Pekka Haavisto, chairman of UNEP’s DU assessment team, stresses that there are “considerable scientific uncertainties” about the safety of the groundwater. “Additional work has to be done to reduce these uncertainties and to monitor the quality of the water,” he says. The UNEP report also recommends that all the sites in Kosovo contaminated with DU should be cleaned up. “DU can still pose risks,” cautions UNEP executive director, Klaus Töpfer. “Our report highlights a series of precautionary measures that should be taken to ensure that the areas struck by DU ammunition remain risk-free.” Scientists also confirm that the seven and a half DU shells they found in Kosovo last November contained traces of plutonium. Although the amounts were too small to add any significant radioactivity, they did suggest that the uranium had been burnt in nuclear reactors. The 19 members of NATO, which co-ordinated the military action in Kosovo, are currently discussing whether a DU clean-up is necessary and, if so, how it would be conducted and funded. “The UNEP report adds further information to the public debate about DU,” a spokesman for NATO told New Scientist. More at: