olgakurt
06/14/2001, 01:11 PM
Radioactive iodine in central Sweden and beyond
American Chemical Society web site ES&T June 1, 2001 / Volume 35 , Issue 11 / p 228 A.
Researchers at Uppsala University have detected radioactive iodine-129 (129I) levels in surface water and precipitation in central Sweden that are 3–4 orders of magnitude higher than prenuclear-era values (Environ. Sci. Technol. 2001, 35 (8), 1579–1586). Although most experts believe that current 129I levels do not pose a danger to human health, there is concern that safe levels could be exceeded in the future if nuclear fuel-reprocessing facilities continue to discharge waste into the environment. Some argue, however, that 129I is unlikely to ever reach levels that are of concern to human health. What is more important, they say, is that if large amounts of 129I are being produced, large amounts of more dangerous radionuclides, such as krypton-85 (85Kr), which is less readily measured than 129I, are also being produced.
129I has a half-life of about 15.7 million years, whereas 85Kr has a half-life of about 10 years. Although 129I will be in the environment for a long time, in some ways its long half-life makes it more safe, says Jean E. Moran of Lawrence Livermore National Laboratory. “129I goes right for your thyroid, but in your body there won’t be much decay,� says Moran. In fact, it’s such a weak beta decay that it’s unlikely to ever reach dangerous levels, she says.
Nonetheless, 129I is long-lived and relatively easy to measure at levels present today in the environment. Unlike most other radionuclides produced during the nuclear bomb testing era between 1945 and the early 1960s, 129I has not returned to near-prenuclear values (105–106 atoms/L in the ocean).Instead, levels of 129I continue to increase globally because of releases from two key nuclear fuel-reprocessing facilities in Europe—Sellafield in England, and Cap de La Hague in France. 129I from these two facilities has even been detected in precipitation in the continental United States (Environ. Sci. Technol. 1999, 33 (15), 2536–2542), although U.S. levels are 1–2 orders of magnitude lower than those in countries, such as Sweden, which are closer to the source.
“These two facilities have been pouring a lot of 129I into the North Sea and the English Channel, and part of it has already been transported into the Arctic Ocean,� says Ala Aldahan, lead author of the Swedish group’s paper. “129I levels in the North Sea are about 1012 atoms/L. We are seeing 129I values of 109–1010 atoms/L in the rain in Sweden,� says Aldahan. “Scandanavia is becoming more and more like a disposal site for waste from central Europe. We have some of the most contaminated waters outside of the Baltic Sea, between Denmark and Sweden,� he says.
ldahan and his colleagues plan to continue monitoring levels of 129I in precipitation and surface water in central Sweden and have now expanded their efforts into the far north of Sweden (latitude 70°) and southern Sweden near the North Sea. They are also looking at iodine in all of the rivers around the Baltic Sea. “We see variable discharges,� says Aldahan. “Southern Swedish rivers have higher concentrations of
iodine than the northern rivers.� About 90% of the 129I in nuclear fuel-reprocessing waste is discharged directly into the ocean. The other 10% is released into the atmosphere. “In Europe, they regulate what goes out of their pipes into the English Channel. They know where those pipes are, and it’s pretty easy to measure what is coming out of them. What has been released into the atmosphere and where it has been deposited on land is less well known,� says Moran.
“It takes a little over a week for an air mass to get all the way around the globe. Certainly, some of the iodine that makes it up into the higher parts of the atmosphere is going to make it all the way around to the continental United States,� adds Moran.
Environmental groups in Europe are worried that France and the United Kingdom are becoming nuclear waste dumps, because Sellafield and La Hague accept nuclear waste for reprocessing from other countries around the world. In April, Greenpeace activistschained themselves to railroads in Germany, attempting to stop a shipment of nuclear waste en route to La Hague for reprocessing.
American Chemical Society web site ES&T June 1, 2001 / Volume 35 , Issue 11 / p 228 A.
Researchers at Uppsala University have detected radioactive iodine-129 (129I) levels in surface water and precipitation in central Sweden that are 3–4 orders of magnitude higher than prenuclear-era values (Environ. Sci. Technol. 2001, 35 (8), 1579–1586). Although most experts believe that current 129I levels do not pose a danger to human health, there is concern that safe levels could be exceeded in the future if nuclear fuel-reprocessing facilities continue to discharge waste into the environment. Some argue, however, that 129I is unlikely to ever reach levels that are of concern to human health. What is more important, they say, is that if large amounts of 129I are being produced, large amounts of more dangerous radionuclides, such as krypton-85 (85Kr), which is less readily measured than 129I, are also being produced.
129I has a half-life of about 15.7 million years, whereas 85Kr has a half-life of about 10 years. Although 129I will be in the environment for a long time, in some ways its long half-life makes it more safe, says Jean E. Moran of Lawrence Livermore National Laboratory. “129I goes right for your thyroid, but in your body there won’t be much decay,� says Moran. In fact, it’s such a weak beta decay that it’s unlikely to ever reach dangerous levels, she says.
Nonetheless, 129I is long-lived and relatively easy to measure at levels present today in the environment. Unlike most other radionuclides produced during the nuclear bomb testing era between 1945 and the early 1960s, 129I has not returned to near-prenuclear values (105–106 atoms/L in the ocean).Instead, levels of 129I continue to increase globally because of releases from two key nuclear fuel-reprocessing facilities in Europe—Sellafield in England, and Cap de La Hague in France. 129I from these two facilities has even been detected in precipitation in the continental United States (Environ. Sci. Technol. 1999, 33 (15), 2536–2542), although U.S. levels are 1–2 orders of magnitude lower than those in countries, such as Sweden, which are closer to the source.
“These two facilities have been pouring a lot of 129I into the North Sea and the English Channel, and part of it has already been transported into the Arctic Ocean,� says Ala Aldahan, lead author of the Swedish group’s paper. “129I levels in the North Sea are about 1012 atoms/L. We are seeing 129I values of 109–1010 atoms/L in the rain in Sweden,� says Aldahan. “Scandanavia is becoming more and more like a disposal site for waste from central Europe. We have some of the most contaminated waters outside of the Baltic Sea, between Denmark and Sweden,� he says.
ldahan and his colleagues plan to continue monitoring levels of 129I in precipitation and surface water in central Sweden and have now expanded their efforts into the far north of Sweden (latitude 70°) and southern Sweden near the North Sea. They are also looking at iodine in all of the rivers around the Baltic Sea. “We see variable discharges,� says Aldahan. “Southern Swedish rivers have higher concentrations of
iodine than the northern rivers.� About 90% of the 129I in nuclear fuel-reprocessing waste is discharged directly into the ocean. The other 10% is released into the atmosphere. “In Europe, they regulate what goes out of their pipes into the English Channel. They know where those pipes are, and it’s pretty easy to measure what is coming out of them. What has been released into the atmosphere and where it has been deposited on land is less well known,� says Moran.
“It takes a little over a week for an air mass to get all the way around the globe. Certainly, some of the iodine that makes it up into the higher parts of the atmosphere is going to make it all the way around to the continental United States,� adds Moran.
Environmental groups in Europe are worried that France and the United Kingdom are becoming nuclear waste dumps, because Sellafield and La Hague accept nuclear waste for reprocessing from other countries around the world. In April, Greenpeace activistschained themselves to railroads in Germany, attempting to stop a shipment of nuclear waste en route to La Hague for reprocessing.