Abstract
Abstract Lombok strait is outflow of water masses from the Pacific Ocean to the Indian Ocean by Indonesian Throughflow (ITF). Radioecology studies in these waters were including monitoring of natural and artificial radionuclide. This study aims to obtain baseline data of artificial radionuclide 137Cs that entering from the Pacific Ocean through the Makassar Strait. The sampling location were covered territorial waters of Bali and Lombok. A large volume sample preparation for the 137Cs analysis were performed by co-precipitation process using K4Fe(CN)6 and CuCl2 at pH 8-9. Measurement of the concentration activity of natural radionuclides and 137Cs were using Gamma HPGe spectrometer with 20 – 25 % efficiency. The result of this study indicate the average concentration of 40K 226Ra 212Pb 214Bi 228Ac 214Pb and 137Cs in the sediments of Strait Bali waters respectively 165.16 Bq kg-1, 25.11 Bq kg-1, 8.36 Bq kg-1, 7.51 Bq kg-1, 7.05 Bq kg-1, 6.68 Bq kg-1 and the lowest of 0.15 Bq kg-1. In the waters of Lombok concentration activity of radionuclides 40K 226Ra 212Pb 214Bi 228Ac 214Pb and 137Cs in the sediments was 172.00 Bq kg-1, 25.88 Bq kg-1, 10.10 Bq kg-1, 6.50 Bq kg-1, 6.39 Bq kg-1, 5.70 Bq kg-1 and 0,162 Bq kg-1. The concentration activity of 137Cs in seawater of Bali and Lombok respectively was 0.113 Bq m-3 and 0.644 Bq m-3. Keyword : Natural Radionuclide, 137Cs, Lombok Strait
Highlights
Lombok Strait located in coordinates of 115 ° 37 'E - 116 ° 02' E and 8 ° 20 'S - 8 ° 50' S represents the marine waters between the islands of Bali and Lombok and connects western seas of Flores and the Indian Ocean
The Lombok Strait was route of water mass from Pacific Ocean into Indian Ocean via Indonesian Throughflow (ITF), which is influenced by differences of sea level, temperature and salinity (Brink and Robinson, 2005)
137Cs and 134Cs were conservative radionuclides that are very soluble in sea water, so their distribution in the ocean is strongly influenced by physical process of mixing and diffusion
Summary
Lombok Strait located in coordinates of 115 ° 37 'E - 116 ° 02' E and 8 ° 20 'S - 8 ° 50' S represents the marine waters between the islands of Bali and Lombok and connects western seas of Flores and the Indian Ocean. The Lombok Strait was route of water mass from Pacific Ocean into Indian Ocean via Indonesian Throughflow (ITF), which is influenced by differences of sea level, temperature and salinity (Brink and Robinson, 2005). The water mass from the Pacific Ocean enters to Indonesian Seas through two entrances i.e west channel and east channel. The western channel which is the main inflow water from the Pacific Ocean transports 11.8 Sv through the Makassar Strait and exits the Lombok Strait and partially into the Banda Sea through the Flores Sea and Timor Sea into the Indian Ocean. The eastern channel of water mass enters through Halmahera and Maluku Seas and pass through the strait of Ombai and Timor Passage to Indian Ocean (Gordon et al, 2003, Gordon et al, 2010). In addition the large quantities of this water mass from ITF contains 137Cs radionuclide caused by nuclear activity in the Pacific Ocean
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