The analysis of cessium-137 activity of sediment surface by gamma spectroscopy methods on dry season at Cilacap Donan Estuarine 2014

Transcription

1 SC.179 Proceedings of the IConSSE FSM SWCU (2015), pp. SC ISBN: The analysis of cessium-137 activity of sediment surface by gamma spectroscopy methods on dry season at Cilacap Donan Estuarine 2014 Nusantara Maritime Academy, Indonesia Abstract The research of radionuclide activity cesium-137 which is the anthropogenic radionuclide have been carried out on sediments surface at Cilacap Donan Estuarine. The samples taken on October 2014, the end of dry seasons. Analysis has been carried out by gamma spectroscopy, samples were taken at three stations. There is a first station (near the cement factory), the second station (near the refinery), and Station III (near the Harbour). The result showed that the activity mean of cesium-137 of sediment surface are (0.181±0.015) Bq/kg.this condition indicates that there are many activities peoples such as industries, domestics, agricultures and transportations were produce cesium waste. Keywords anthropogenic, cesium-137, estuarine, radionuclide, sediment surface 1. Introduction The cesium-137 is radionuclide included in the category of anthropogenic radionuclides. The half life years. Existence in the universe as an impact of human activities, for example reactor accident, the disaster of nuclear experiment and the used of medical equipments. Cesium is also found naturally in the environment mostly from the erosion and weathering of rocks and minerals. Cesium is also released into the air, soil, and water (Haidir, 2010). Chernobyl nuclear power plant (NPP) accident in 1986 and Fukushima NPP in 2011 were enriched anthropogenic radionuclides to environment. Which one of the radionuclide element is cesium-137. Indonesian region there is rarely a source of anthropogenic radionuclides, but many of the events that resulted in the release of radionuclides satisfied seawater enriched radionuclides in Indonesia. This happens because the global flows (The Great Ocean Conveyor Belt) from the Pacific Ocean through the Indonesian waters of the Indian Ocean (Kurniawan, 2014). Artificial radionuclide which produce cesium-137 are activities of food preservation industry and control in the production process. The artificial radionuclides is also used in medicine, for the sterilization process and radiographic, and food industries that need preservation by irradiations (Wardhana, 2007). The mean of Cs-137 concentration of sea in the world resulting from fallout is about 2x10ˉ³Bq/kg, The mean of Cs-137 concentrations in surface sea water in the Asia Pacific about 3x10 ˉ³Bq/kg, in the South Pacific ocean around ( )x10ˉ³ Bq/kg, and in the Indian Ocean range between ( )x10ˉ³ Bq/kg (Makmur, 2004).

2 The analysis of cessium-137 activity of sediment surface by gamma spectroscopy methods on dry season at Cilacap Donan Estuarine 2014 SC.180 Donan waters Estuarine is adjacent to an industrial area, Cilacap City, and harbour allow for waste containing radionuclides cesium. Cilacap coastal waters many industrials such as Holcim (Cement plant), Pertamina (Refinery plant) and Harbor, resulting disposal which contain of radionuclide (, 2013). The goals of this paper is to investigate the activity of the radionuclide cesium-137 on sediment surface of Donan Estuarine waters and determine the source of radionuclide so can to know the strategy of management / utilization of estuarine. 2. Methodology The study was conducted at three observation stations in coastal waters, around Donan Estuarine. Station 1 is located at (7⁰40.766, 109⁰00733 ), near the cement factory, while Station 2 is located at ( 7⁰41.308' S, 108⁰59.684'), near the Pertamina refinery and station 3 (7⁰41.453'S, 108⁰29.791), near the Harbor, where there are frequent stops ships lining up to enter the port area. Detailed maps can be seen in Figure 1. Figure 1. Research site at Donan Estuarine. The experiment was conducted at October 10, 2014 which was the peak of the dry season (end of the east wind/transition), the discharge current of Donan river is in a minimum condition. The Measurement and analysis techniques used gamma spectroscopy method, namely gamma rays spectrometry, the rays are produced by the radioactive substances, research procedure is presented in Figure 2. Sediment sampling equipment includes compreng boat with a counterweight, a device to obtain sediment (Eikman grab), global positioning system (GPS), the preparation apparatus of Spectrometer, and the gamma spectrometer.

3 SC.181 Figure 1. Scheme of Cs-137 Radionuclide with Gamma Spectrometer. Sampling is done in the Donan Estuarine of Cilacap, preparation footage to the analysis performed on nuclear energy agency (BATAN) Yogyakarta. Amount of sediment footage taken of each station is 5 kilograms, from the bottom waters with depths 4 8 meters. Dried by the sun for 3 days, then in doing preparation in BATAN Yogyakarta, in mash until smooth with a mesh size of 450 μm, standards-compliant marine sediments (Certificate Reference Material CRM-315, IAEA). The next step footage placed in a sealed container which is heated at a temperature 60 ⁰C, on leave for 40 days in order to obtain a balanced condition of Cs-137 as well as elements of disintegration, especially in order to be free from volatile radon. 3. Result and discussion The results of measurements and radionuclides analysis cesium-137 are shown in Table 1. Table 1. Cesium-137 radionuclide activity at three observation stations in Donan Estuarine. Sampling on October 10, 2014, the tide conditions at 11 am 1 pm. No. Stations Salinity (ppt) Experiments result (Bq/kg) 1 I 29 0,192 ± 0,013 2 II 30 0,224 ± 0,018 3 III 31 0,126 ± 0,014 Results of measurement and analysis was showed that the activity mean of the radionuclide cesium-137 on the sediment surface is 181x10ˉ³ Bq/kg. if consulted with the measurement results reported by Makmur (2004 ) which states that the activity of cesium- 137 in the Indian ocean is varied ( )x10ˉ³ Bq/kg or mean is 1.41x10ˉ³ Bq/kg showed a higher number. Comparisons of cesium activity on sediment and sea water is The comparisons of radionuclide activity Kalium-40, Thorium-232 and Uranium-238 of sediment surface and sea water above it is measured by (2013) are 205.7, 177.3

4 The analysis of cessium-137 activity of sediment surface by gamma spectroscopy methods on dry season at Cilacap Donan Estuarine 2014 SC.182 and 61.7, respectively. So the activity of cesium-137 in surface sediments in estuaries Donan is reasonable activity, such as elements of other radionuclides, which was the environmental impact of industrial and domestic. October 2014 (the end of the dry season ) almost no sediment carried by the river flow Donan towards the estuarine, because the river Donan including small and short streams, sediment transport only season when flooding in the rainy season (Subardi, 1994). The dry season radionuclide cesium-137 comes from falling out due to industrial, transport and domestic waste, that settles in the bottom waters during the dry season. On July to October winds ranged from 95 to 175, which is between the east to southeast (, 2014). Cesium-137 is the element that is soluble and high toxicity (Wardhana, 2007) and cesium is an element fission of uranium and plutonium (Sanusi, 2008). then its existence on the sediment surface needs to know accurately and must be controlled for save of survival biota. According to the regulation of the nuclear energy agency number 9 of 2009 on intervention against exposure originating Technologically Enhanced Naturally Occurring Radioactive Material, The safe threshold or maximum permissible emission limits on the sediment surface is 1 Bq/g (one becquerel per gram) for each member of the uranium and thorium series radionuclides, including cesium isotops, equal to 1000 Bq/kg. Thus the emission of radiation at the surface sediments in Donan waters estuarine still below the threshold. Cesium-137 activity is highest in station II (0.224 Bq /kg), possible presence of radioactive fallout from the chimney of refinery (pertamina), that located quite close to this location. The second order of cesium activity is the first station (0.192 Bq/kg), which is close to the factory cemen and lowest at station III which is the boundary between the sea estuaries and the ocean. Based on the results of measurements of the activity of cesium-137 on dry season, the concentration of cesium 137 is not dangerous to the environment, estuarine areas Donan still feasible for the conservation, maintenance and harbor fish, used as day. 4. Conclusion and recommendation Sediment surface of Donan estuarine on the dry season has been contaminated by radionuclides cesium-137 of 0,18 Bq/kg, but still under of the threshold that is safe for the environment, so the estuarine region is suitable for fishing, conservation and harbor. Needs to be studied radionuclides cesium-137 contamination for the animals that live in the sediment, especially mussels and shrimp. References Haidir, M., Rosmini, D., & Tjahaja, P.I. (2010). The elimination of radionuclide Cs-134 from andisol soil by mustard plant (Brassica Juncea). E-Journal PI EM-4. Kurniawan, S., Muslim, & Suseno, H. (2014) Study of cesium-137 radionuclide contents in sediment at Muria Peninsula Jepara Regency. Journal of Oseanografi, 3(1), Makmur, M. (2004) Determination of Cs-137 by quick methods in sea water. Bulletin Limbah, 8(2), Tusiro, Z., Koenawan, & Willian (2012). The analysis of cesium-137 radionuclide content in sediment at Batam Sea Ocean. E-Journal ,IKL-2. Subardi, & Sidabutar, S.M. (1994). Sediment transport from the mainland to the marine environment.

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