|Year : 2015 | Volume
| Issue : 3 | Page : 72-77
Marine environmental radioactivity measurement programme in India
SK Jha, SJ Sartandel, RM Tripathi
Environmental Radioactivity Measurement Section, Health Physics Division, Bhabha Atomic Research Centre Trombay, Mumbai, Maharashtra, India
|Date of Web Publication||10-Nov-2015|
S K Jha
Environmental Radioactivity Measurement Section, Health Physics Division, Bhabha Atomic Research Centre Trombay - 400 085, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
Coastal marine Environmental Radioactivity Measurement Programme in India assume significance in view of massive expansion of nuclear power plants in the Asia Pacific region and to establish benchmark of specific radionuclides in coastal marine environment. In the present study Marine Environmental Surveillance was carried out along the east and west coast of India. Fallout out 137 Cs and naturally occurring 226 Ra, 228 Ra were assessed by in house developed in-situ pre-concentration method using copper ferrcyanide and manganese di-oxide coated filter cartridges. 137 Cs activity concentration mapped for Indian coastal region varied from 0.30 to 1.25 Bq m -3 and these were compared with 137 Cs levels of Asia Pacific Region. The marine surveillance data also indicates no input from any source including operation of nuclear power plant in east and west coast of India.
Keywords: Activity concentration, Indian coast, large volume, pre-concentration
|How to cite this article:|
Jha S K, Sartandel S J, Tripathi R M. Marine environmental radioactivity measurement programme in India. Radiat Prot Environ 2015;38:72-7
|How to cite this URL:|
Jha S K, Sartandel S J, Tripathi R M. Marine environmental radioactivity measurement programme in India. Radiat Prot Environ [serial online] 2015 [cited 2019 Jun 20];38:72-7. Available from: http://www.rpe.org.in/text.asp?2015/38/3/72/169368
| Introduction|| |
Environmental monitoring is one of the major activities necessary to ensure protection of environment and human health from the wide spectrum of materials released into the environment as a result of technological developments. The unique activities of assessing the impact of operations beyond plant boundaries were initiated by the nuclear industries as an operational responsibility right from its inception. The care and concern for the environment shown by the nuclear industries slowly permeated to have environmental activities and today it is mandatory to have an environmental impact assessment and environmental management plan for any proposed industrial activities. It is particularly significant that marine environmental surveillance program for nuclear technological development in our country was started at a time when environmental data were either sparse or nonexistent at most of the locations. The understanding and the evaluation of the possible interaction of various anthropogenic pollutants with the coastal marine environment of the east and west coast of Indian sub-continent assumed significance about five decades ago with the setting of nuclear power plants, release of industrial, domestic, and sewage waste in coastal water.  The initiation of the marine monitoring program of the environmental studies for nuclear sites was made at Trombay following the setting of the research center in 1957.
The study of radioactivity in the marine environment is filled with challenges. The sea and their depths are not easily accessible; the environment is ever changing, and special techniques are needed for the measurement of very low-level of radionuclides present. Environmental radioactivity measurement facilitated in; (i) assessing the short-term and long-term impact of man-made sources of marine radioactivity, (ii) characterizing the distribution of key radioactivity pollutants in regional ocean/sea, (iii) establishing benchmark of specific radionuclides in coastal marine environment against which future man-made contribution can be assessed, (iv) understanding transport process and the fate and behavior of pollutants in marine environment. , In the past decades, the method for detection and measurement of radioactivity in the marine environment has improved vastly, and a large database has been generated.
| Sources of radioactivity in marine environment|| |
Environmental radioactivity is ubiquitous and virtually all materials in the environments on our planet are exposed to ionizing radiation. The two sources of radioactivity in the marine say, seafood, as with the terrestrial environment, are natural and artificial. [Table 1] gives the overall estimate of radioactivity in oceans. The naturally occurring predominant radionuclides are 40 K with a half-life of 1.28 × 10 9 years, 232 Th with a half-life of 1.405 × 10 10 years, and 238 U with a half-life of 4.468 × 10 9 years. Both 232 Th and 238 U have decay products that also contribute to the of humans from consumption of seafood. One of these decay products, alpha-emitting 210 Po from the 238 U decay series, is considered to contribute significantly to dose from ingestion of marine products.  Its parent in the decay series, 210 Pb, serves as a natural tracer that provides historical information on land-based and atmospheric inputs into the marine environment. In the recent years, there has also been an increased recognition of the radiological significance of nonnuclear process of natural radioactivity build-up in particular, 226 Ra, 228 Ra, 222 Rn, 210 Po, and 210 Pb produced, for example by phosphate processing plants, offshore oil and gas installations, and ceramic industries, etc., UNSCEAR-2000. 226 Ra an alpha emitter (half-life = 1602 years) of the primordial 238 U decay series and 228 Ra an beta emitting particle (half-life = 5.8 years) of 232 Th decay series. Distribution of radium isotopes in the water column depends  on their respective half-lives as well as the distribution of their parent nuclides in the sediments. In the light of the possible radio-ecological significance  in the environment, investigation of the distribution of 226 Ra and 228 Ra in sea water was a part of the environmental surveillance program. 
However, artificial radionuclides or radionuclides associated with human activities have become to a large extent, the focus of regulatory control. The major sources of artificial radionuclides in the marine environment are:
Of these major sources, atmospheric nuclear weapon testing is considered as the most significant contributor to the presence of radionuclides in the marine environment. 
- Nuclear weapon testing in the atmosphere or under water
- Controlled, routine release of low-level radioactive effluents by nuclear power plant and related installations
- Nuclear accidents such as the Chernobyl accident accidents involving nuclear-powered submarines, or reentry of satellites with radioactive materials
- Sea dumping of radioactive waste.
In 1946, the first planned disposal of packaged radioactive wastes into the deep sea took place in the Northeast Pacific Oceans. This waste management strategy was adopted in order to isolate radionuclides from man's terrestrial environment, while allowing these radionuclides to decay to a level that no longer pose an unacceptable health risk to man. In 1972, the convention on the prevention of marine pollution by dumping of wastes and other matter which was held in London, that is, London Dumping Convention (LDC) was adopted and later entered into force in 1975. The LDC designated International Atomic Energy Agency (IAEA) as the international competent authority with respect to sea dumping of radioactive wastes. In 1983, a nonbinding moratorium on sea dumping was proposed by LDC. Thus, the last sea dumping operation on record was in 1982 in the Atlantic Ocean. In the span of 36 years, 12 countries have disposed in 47 sites, a total of about 46 PBq or 1.24 MCi of mainly solid or solidified low-level radioactive waste in the sea.
From the prospects of regulatory agencies, a database dealing mainly with the artificial radionuclide will be useful to provide benchmark values in order to assess the impact of future radionuclide input into the marine environment. Among these artificial radionuclides, 137 Cs and 239],[240 Pu were considered of primary interest in terms of existing inventories and significance to health. Both these radionuclides are considered as important indicators of radioactive pollution of the marine environment and good tracers of water movement.
| Sampling and measurement|| |
A wide range of seafood and indicator materials routinely monitored in environmental surveillance are reported in [Table 2]. The frequency of measurement depends on the level of environmental impact from the source under scrutiny, with the intervals between measurements varying between 1-week and 1-year. Indicator materials such as seawater, sediment, and biota are sampled to provide information on current status and trends in contamination levels in the environment. These materials can concentrate particular radionuclides and offer a cost-effective means of determining levels of activity in the environment. Generated data helps to distinguish contributions to the overall dose rates from artificial and natural radionuclides.
|Table 2: Details of sample preparation, analytical techniques, detection limits, and observed normal range of radionuclides involved in regular environmental surveillance in sea water |
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The natural and man-made radionuclides as discussed in [Table 1] in seawater exists in trace levels, which quite often present difficulties in actual measurement by employing existing method. To generate data on activity in radium in marine seawater, on-site pre-concentration using MnO 2 coated polypropylene filter cartridges was adapted.  After pre-concentration, the cartridges were ashed in a furnace at 500-550°C, filled in standard geometry and analyzed by gamma-ray spectrometric technique.
The common practice of 137 Cs measurement was by adsorption of the radionuclides on ammonium phosphomolybdate which is routinely used in the laboratory. This is effective with samples containing significant activity. In case of measurement of low-level activity such as fallout levels, a large volume of sea water is required to be sampled. In this situation, collecting hundreds of liters of water from different locations, field processing such as acidification, tracer addition, transportation, etc., will add to the complexity in the measurement of the activity.  In the new developed method cesium isotope in dissolved phase was sequestered using sorption material copper ferrocyanide coated on 1 μm pore size filter cartridge. [Figure 1] gives the various process involved in sample preparation and measurement of 137 Cs in sea water. The preconcentrated copper ferrocyanide cartridges were ashed in a furnace at 350°C and analyzed using gamma spectrometric technique [Figure 2].
|Figure 2: Acquired gamma spectrum of Cs-137 preconcentrated on copper ferrocyanide impregnated filter cartridge|
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| Quality control and quality|| |
Marine environmental radioactivity laboratory developed procedure appropriate for Indian condition, documented and implemented an appropriate (quality control [QC]) program. Accurate and precise determination of radionuclide concentrations in marine samples is crucial for reliable marine radioactivity assessment. Validity of the environmental monitoring data is ensured by proper choice of sampling location, sampling frequency, adoption of appropriate sensitive techniques, counting instruments, and QC program. Periodic inter-laboratory and intercomparison exercise, use of reference sample, and replicate analysis are some of the programs perused for ensuring the reliability of analytical results. Environmental Radioactivity Measurement Section; Health Physics Division had participated in special proficiency test organized in the frame of the IAEA Technical Cooperation project RAS/7/021. This proficiency test involved checking national capability in field measurement, homogenization, and developed analytical method for low-level contamination of cesium isotopes in sea water. The results of proficiency test as depicted in [Figure 3] validated the in situ pre-concentration of high volume sea water for cesium radioisotopes. The results also ensure the international community for the accurate and precise determination of radionuclide activity in sea water.  The laboratory is also regularly participating in the measurement of environmental radioactivity and other intercomparison exercise conducted by national and international agencies. [Table 3] gives the results of a few participated international intercomparison exercises.
|Figure 3: Results of special proficiency test conducted under RAS/7/21 "Marine Benchmark study on the possible impact of the Fukushima radioactive releases in the Asia-Pacific Region"|
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| 137Cs Distribution in Indian Coastal Region Compared to Asia-Pacific Region|| |
The absence of significant radionuclide sampling mission for 137 Cs concentration in the Indian coastal region was mainly due to a number of constraints which includes, requirement of large volume samples, cumbersome chemical separation from large samples size, time constraint, financial constraint, etc., Only very limited studies were carried out in Indian Oceans to understand the spatial variation of 137 Cs in the coastal area of India. With the developed capability, an attempt has been made for low-level measurement to trace anthropogenic 137 Cs contribution due to global fallout in sea water of Indian coastal area at the national scale. India also actively participates in regional and international initiated activities in marine pollution studies and controls. For the marine radioactivity database, India has participated in following international marine projects namely; RAS/8/083 management of the marine coastal environment and its pollution (1996-1999), RAS/7/011 enhancing the marine coastal environment phase II (1999-2003), ROK/06/001 mitigation of coastal impact of natural disasters like tsunami, using nuclear or isotope-based techniques (post tsunami environmental impact assessment) (2006-2009), RAS/7/016 establishment of a benchmark for assessing the radiological impact of nuclear power activities on the marine environment in the Asia-Pacific region (2007-2011) and the on-going RAS/7/21 marine benchmark study on the possible impact of the Fukushima radioactive releases in the Asia-Pacific region (2011-2015).
The study has helped in understanding the behavior of existing 137 Cs global fallout level and its depletion from surface seawater of Asia-Pacific region. [Figure 4] gives the frequency distribution of 137 Cs concentration in the Arabian Sea which indicates the maxima at 0.80 Bq m−3 . [Figure 5] shows nonuniform distribution of 137 Cs concentration at the different sampling locations covering the Indian coastal region extending from 8.09°N 77.43°E to 22.48°N 69.07°E along the western coast and 8.06°N 77.55°E-21.60°N 87.53°E along the eastern coast.  Mean 137 Cs activity concentration in surface water was found to vary from 0.09 to 1.30 Bq m−3 with an overall mean of 0.69 ± 0.29 Bq m−3 . The obtained value lies in the range appeared in the Asia-Pacific marine radioactivity database 0.26-11.47 Bq m−3 [Figure 6]. 
|Figure 5: 137Cs activity concentration in costal marine environment of India|
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|Figure 6: Frequency distribution of 137Cs activity concentration in Asia-Pacific region|
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| Conclusions|| |
The observed concentration of 137 Cs in the offshore coastal environment was found to be lower as compared with the marine water of Asia-Pacific region. The marine surveillance data also indicate no radionuclide contribution from any source including the operation of the nuclear power plant in East and West coast of India. Frequent participation in intercomparison exercise conducted by international agencies has increased the reliability of generated data. The result will be useful as the reference source on the average level of 137 Cs in the surface water of Indian coastal environment.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3]