An airborne sampling system using a spin trapping method has been developed to determine the concentration of hydroxyl radical in the troposphere. Hydroxyl radical was trapped In a «-4-pyrldyl-Af-fert-butylnltrone a-1-oxide (4-PO-BN) In situ to form a stable hydroxy adduct of 4-POBN and determined by electron spin resonance (ESR) later In the laboratory. The concentration of hydroxyl radical ranged from less than 5 X 10s molecules/cm3 at an altitude of 10 km to a maximum of 5 X 106 molecules/cm3 at an altitude of 6 km at 37°N 140°E during the period of May 1980 to Feb 1981. The limit of detection of the present system was about 5 X 10s molecules/cm3 If 200 m3 of air was sampled. The uncertainty of the concentration was estimated to be less than 30%.is now recognized to be of prime importance (2-4). It controls the concentration of various trace species such as CH4, CO,

No abstract

Depth profile and inventory of fallout 237 Np in sediment cores from the Mikata Five Lakes and Nyu Bay located in the coastal area of the Sea of Japan have been studied together with those of Pu isotopes ( 238 Pu, 239 -24°P u and 241 Pu), 241 Am and 137 Cs to understand the sedimentation behaviors of these elements under different aquatic environments. Mikata Five Lakes has different water salinity levels in a narrow area: fresh water (Lake Mikata), brackish water (Lakes Kugushi, Suigetsu and Suga) and sea water (Lake Hiruga).The inventory of 239,240 Pu estimated from measured depth profiles ranged from 109 to 347 MBq/km 2 . The depth profiles of 237 Np and 241 Am in sediment cores were similar to that of 239,240p u Gn the basis of a comparison of the 237 Np/ 239 -240 Pu inventory ratio obtained in sediment cores with that in surface soils, Np is considered to be more soluble than Pu in an aquatic environment. The 241 Am depth profile observed can well be explained by the ingrowth from parent 241 Pu by assuming the USA nuclear tests during the late 1950's as a substantial source of this nuclide and the immobilization of Pu and Am in the sediment. The 239,240 Pu/ 137 Cs inventory increased from 0.027 to 0.38 with the increase of salinity of the water.

No abstract

No abstract