**6. Radiation effects on ecosystems**

Since the early 1960's there have been numerous studies on the effect of gamma radiation on ecosystems. These studies were fueled by the arms race between the Soviet Union and the United States (Stalter and Kincaid 2009). After lengthy negotiations between the two powers the SALT (Strategic Arms Limitation Treaty) was signed in 1971 and extended in 1977. With the signing of the treaty, less funding for irradiation studies was available (Stalter and Kincaid 2009). Thus most studies cited in this paper are those conducted prior to the SALT agreement of 1971. The gamma source that has been used has been either cesium 137 or cobalt 60. These include the studies of Woodwell (1962, 1965a) at Brookhaven National Laboratory, Long Island, New York, a tropical rain forest , Puerto Rico (Odum and Pigeon 1970) and the desert of Nevada (French 1965). Additional studies have been conducted in the fields and forests of Georgia (Odum and Kuenzler 1963) (Platt 1965), and Oak Ridge, Tennessee (Witherspoon 1965, 1969). Much additional work involving a portable gamma source on plant communities has been conducted at the Savanna River Ecology Laboratory, Aiken, South Carolina (McCormick and Platt 1962, McCormick and Golly 1966, Monk 1966, McCormick 1969).

 Stalter and Kincaid (2009) investigated community development following gamma radiation at a pine-oak forest, Brookhaven National Laboratory, Long Island, New York. The objective of this study was to compare vascular plant community change at five vegetation zones the site of Woodwell's (1962) gamma irradiated forest (Figure 1). The zones were: the dead zone where all vegetation was killed; a gramminoid *Carex pensylvanica* zone; an ericaceous zone; an oak dominated zone; and a control, the original oak pine forest. Radiation greater than 63,000 roentgens killed all vegetation. *Carex* dominated the zone receiving 27,000 to 63,000 roentgens, ericaceous shrubs, *Vaccinium* spp. and *Gaylussacia baccata* were dominant at the zone receiving 11,000 to 27,000 roentgens while oaks survived at the zone receiving 3600 to 11,000 roentgens. Upon completion of the Woodwell study in the 1970's, pitch pine (*Pinus rigida*) has invaded the total kill zone as bare mineral soil favors pine regeneration (Stalter and Kincaid 2009). *Carex* remained the dominant taxon in the

radioactive fallout from Chernobyl. Ultimately the rabbits were destroyed because of the

There are differences in the kind of radionuclides that enter terrestrial and marine food chains. Soluble fission products, strontium 90 and cesium 137, are generally found in the highest amounts in land plants and animals. In marine systems fallout that forms strong complexes with organic matter such as cobalt 60, iron 59, zinc 65, and manganese 54 are most likely to be concentrated in marine organisms. In addition, those found in colloidal form such as cesium 134 and zirconium 95 are also found in high concentration in marine organisms. Cesium 134 is mostly from the fission products of a power reactor whereas cesium 137 can be formed during atomic power plant accidents or as a product of nuclear

There are additional considerations/problems associated with concentrating radioactive material entering food chains as the concentration of radioactivity is also a function of nutrient richness, and the exchange and storage capacity of soils. Nutrient poor soils and thin soils such as those found on granite outcrops act as a nutrient trap providing more radionuclides to the vegetation. For example, sheep grazing on hill pastures in England accumulated 20x as much strontium 90 in their bones than sheep pastured in deep valleys where calcium content of the soil was higher and the grasses taller (Bryant et al 1957). For additional radiological work on tracers in food chains and trophic levels see Odum and Golley (1963), Odum and Kuenzler (1963), de la Cruz (1963), Ball and Hooper (1963), Foster

Brief descriptions of three power plant accidents in the United States the Soviet Union and Japan follow. The first nuclear power plant accident occurred at 4 am on March 28, 1979, near Harrisburg, Pennsylvania, USA, the state's capital. A malfunction in the cooling system resulted in a portion of the core to melt in the Number 2 reactor. The approximately 2 million people who lived near the plant had an average dose of 0.14 Gy (Rogovin 1980). Although some radioactive gas was released from the plant on the 29th and 30th of March there was, "not enough to cause any radiation dose above background levels in the neighborhood of the accident "(http://www.world-nuclear.org/info/info/info/inf36.html). Fortunately, there were no reported injuries or health issues emanating from the Three Mile

A more serious nuclear accident occurred at the Chernobyl power plant located 80 miles north of the city of Chernobyl in the Ukraine, one of the original Soviet Republics. A "routine" shut down and test that began on the 25th of April, 1986, led to this disaster. At one in the morning, 26 April, the reactor's power source dropped and when the backup safety system failed, the reactor, Reactor Four, exploded. Shortly after the initial explosion at Chernobyl, the Swedish government reported high levels of radiation at their Forsmark nuclear power plant at Stockholm. When additional European nuclear power plants also experienced higher than normal levels of radiation, they contacted the USSR for an explanation. Although initially denying the nuclear disaster, on the 28th of April the USSR

acknowledged that one of their reactors had been compromised.

high concentration of radioactive material in their flesh.

bomb explosions.

Island accident.

(l958), and Foster and Davis (1956).

**9. Nuclear power plant accidents** 

original *Carex* zone demonstrating again that different plant species vary in their tolerance of radiation.

Herbaceous plant communities may be more resistant to radiation than mature forests because many early successional species have small nuclei (Sparrow and Evans 1961) and also because herbaceous taxa like *Carex pensylvanica* have more below ground plant material which is shielded from gamma radiation. Sparrow (1962), Sparrow and Evans (1961), and Sparrow et al (1963) present detailed information on the relationship between nuclear volumes, chromosome numbers and relative radiosensitivity.
