Spatial distribution of cesium-137 in surface soils on the Araya and Paria Peninsulas (Venezuela)

摘要

The activity of cesium-137 (Bq/kg) in surface soils between 2-5 cm was determined for more than ninety sample sites on the Araya Peninsula, the Paria Peninsula and the isthmus in between them in the state of Sucre (Venezuela). The measurements were performed by high-resolution gamma-ray spectroscopy, employing a compatible IBM computer with a Nucleus analog to digital interface card. In general, the values for the 137{sup left}Cs activities were much greater on the Paria Peninsula than the Araya Peninsula and slightly lower on" the isthmus. Even though the peninsulas are only separated by a small isthmus, their environmental characteristics are very different. The large difference in the annual rainfall of the peninsulas could have resulted in a greater amount of deposition of 137{sup left}Cs on the Paria Peninsula, as well as other environmental characteristics, such as altitude and vegetation. The difference of the environmental characteristics could also affect the degree of disturbances of the soils by natural processes on the peninsulas and the isthmus, which could also have affected the I37{sup left}Cs activity distribution. Finally, an anomalous high 137{sup left}Cs activity distribution was found at the farthest southeastern sample sites and one of lesser extent at the most northern sample sites. These anomalies are possibly due the direct affect of the northeasterly winds which transported the 137{sup left}Cs fallout from the nuclear weapon test sites.