After Chernobyl accident wildlife flourishes

After Chernobyl accident wildlife flourishes

Ecological Society of America

August 10, 2005

Chernobyl’s ecosystems seem to be recovering just 19 years after the region was badly contaminated with radiation from a nuclear meltdown. Researchers, who presented the results of suverys around old nuclear power plant at the Ecological Society of America meeting in Montreal, say that biodiversity is actually higher than before the disaster. What follows is a release from the Ecological Society of America.

Nearly 20 years ago Reactor number 4 at Chernobyl exploded, sending radiation across a large region of what is now the Ukraine, Belarus, and Russia. Some 40 radionucleotides were released into the environment, including Strontium 90 (90Sr) and Cesium 137 (137Cs). Yet despite radiation levels dangerous to humans, most natural areas in the region have rebounded, and by ecological standards, are functioning normally. The session, organized by James Morris and Timothy Mousseau (University of South Carolina, US) will reveal how the environment has responded — from genetic mutation rates, to plant and animal communities, to nutrient cycling.

Sergey Gaschak (International Radioecology Laboratory, Ukraine) will open the session with his presentation, “Determinants of levels of 90Sr and 137Cs in birds in Chernobyl.” Studying 228 birds of 23 different species captured in Chernobyl, Gaschak and colleagues from the University of South Carolina (US) and University Pierre et Marie Curie (France) measured the birds’ levels of radioactive strontium and radioactive cesium, comparing migrating populations with those that remain in the area, as well as examining age, sex, and nesting preferences to determine the amounts and types of radiation accumulating in the birds. In the presentation, Gaschak will discuss how quantities of 90Sr and 137Cs vary with feeding, nesting and migration habits.

Timothy Mousseau will present “Consequences of radiation for reproduction and survival of barn swallows Hirundo rustica from Chernobyl.” Barn swallows are long-distance migratory birds, which nest across Europe, providing researchers with numerous populations to sample. Examining swallows from the Chernobyl region and Kanev, southeast of Kiev, Mousseau and his colleague, Anders Moller (Laboratorie de Parasitologie Evolutive, France), found reproductive success was significantly reduced for the Chernobyl-nesting birds. Survival rates, number of eggs laid, and overall body condition was lower, despite similar nesting and laying dates.

Chernobyl disaster [from Wikipedia]

On Saturday, April 26, 1986, at 1:23:58 a.m. local time, the fourth reactor of the Chernobyl power plant—known as Chernobyl-4—suffered a catastrophic steam explosion that resulted in a fire, a series of additional explosions, and a nuclear meltdown.

203 people were hospitalized immediately, of whom 31 died (28 of them died from acute radiation exposure). Most of these were fire and rescue workers trying to bring the accident under control, who were not fully aware of how dangerous the radiation exposure (from the smoke) was. 135,000 people were evacuated from the area, including 50,000 from the nearby town of Pripyat, Ukraine. Health officials have predicted that over the next 70 years there will be a 2% increase in cancer rates in much of the population which was exposed to the 512 (depending on source) EBq of radioactive contamination released from the reactor.

Some children in the contaminated areas were exposed to high thyroid doses up to 50 gray (Gy) because of an intake of radioactive iodine, a relatively short-lived isotope, from contaminated local milk. Several studies have found that the incidence of thyroid cancer among children in Belarus, Ukraine and Russia has risen sharply. The IAEA notes “1800 documented cases of thyroid cancer in children who were between 0 and 14 years of age when the accident occurred, which is far higher than normal” but fails to note the expected rate. The childhood thyroid cancers that have appeared are of a large and aggressive type, and if detected early, can be treated. Treatment entails surgery followed by iodine-131 therapy for any metastases. To date, such treatment appears to have been successful in all diagnosed cases.

Late in 1995, the World Health Organisation linked nearly 700 cases of thyroid cancer among children and adolescents to the Chernobyl accident and among these some 10 deaths are attributed to radiation. However, the rapid increase in thyroid cancers detected suggests that some of it at least is an artifact of the screening process. Typical latency time of radiation-induced thyroid cancer is about 10 years; but the increase in childhood thyroid cancers in some regions was observed as early as 1987. Presumably, either the increase is unrelated to the accident or the mechanisms behind it are not well enough understood.

So far no increase in leukemia is discernible, but this is expected to be evident in the next few years along with a greater, though not statistically discernible, incidence of other cancers. There has been no substantiated increase attributable to Chernobyl in congenital abnormalities, adverse pregnancy outcomes or any other radiation-induced disease in the general population either in the contaminated areas or further afield.

The radio nucleotides in the area also filter into the soil, and from there into plants. Animals that consume these plants, including livestock, then take up the radionucleotides. Viktor Dolin (National Academy of Sciences, Kyiv, Ukraine) will discuss a newly described process of environmental self-cleaning in the talk, “Biogeochemical cycling of radionucleotide: Implications for the human food web.” Dolin calculated the rate of 137Cs and 90Srs moving through the environment, then used the data to determine an ecosystem’s ability to “clean” itself of excess radiation.

Oleksander Orlov’s (Ukrainian Scientific Research Institute) presentation, “The distribution and cycling of 137Cs in forests of the Chernobyl exclusion zone,” will focus on 137Cs levels in three 50-year old Scotch Pine forests. Forest litter, moss, lichens, understory, macromycetes, and canopy 137Cs activity measurements will be described. Also working in these pine forests, Vadim Skripkin and colleagues from the Institute for Environmental Geochemistry, Ukraine and the University of South Carolina will report their findings on the distribution of 14C in, “The turnover of 14C carbon in forests of the Chernobyl exclusion zone.”

The final presentation of the session, Ronald Chesser (Texas Tech University, US) will describe the distribution and effects of radiation doses that hit wildlife that were living in the area at the time of the accident, as well as how the populations recovered in the talk, “Temporal trends in radiation doses, survival, and recovery in wildlife populations at Chernobyl.”

Organized Oral Session 7: “Ecological effects of the Chernobyl disaster: Genes to ecosystems,” will take place Monday 8 August 2005, 1:30 – 5:00 PM in Meeting Room 510 A, Level 5, Palais des congrès de Montréal.

For more information about this session and other ESA-INTECOL Meeting activities, visit: http://www.esa.org/montreal. The theme of the meeting is “Ecology at multiple scales,” and some 4,000 scientists are expected to attend.

Annie Drinkard

annie -AT esa.org

Ecological Society of America

http://www.esa.org

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