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Distribution of some natural and artificial radionuclides in Mangalore environment of South India
.I.Environ. Radioactieif~~. Vol.
Copyright
0
Printed ELSEVIER
30 No. 1. pp. 31 54, 1996 1995 Elsevier Science Limited
in Ireland. All rights reserved 0265-931X/96 $15.00 $ 0.00
0265-931X(95)00037-2
Distribution of Some Natural and Artificial Radionuclides in Mangalore Environment of South India
A. P. Radhakrishna,
Department
H. M. Somashekarappa, & K. Siddappa
of Studies in Physics, Mangalore (Received
14 February
University, 1994; accepted
Y. Narayana
Mangaiagangotri
-
574 199, India
12 May 1995)
ABSTRACT The activities of 40K, 226Ra, 22XRa, “‘PO, 2’“Pb, J37CLsand”‘Sr were determined in a number of natural samples in the environment of Mangalore, South India where large-scale industrial activities are envisaged. Well-established nuclear techniques were employed to measure the activities and wherever necessary radiochemical methods were also followed. The measurement of transfer coef jicients indicated that the uptake ofZZ6Ra, 228Ra and “‘Pb in paddy is higher than that in vegetables. The measured activity ratios of “‘Po: ‘tOPb and 228Ra : 226Ra in soil samples suggest the existence of equilibrium between the corresponding radionuclides in normal background areas and disequilibrium in high background areas. The intake ofradionuclides by the population and the internal dose were estimated. The annual internal efjective dose,for the population is,found to be 341 uSv year-’ which mainly arises from 40K and ‘IoPb.
INTRODUCTION Mangalore city and the surrounding region (Fig. 1) on the west coast of India are on the threshold of becoming a major industrial area. In addition to the existing big chemical and fertilizer factories, an iron ore pelletisation plant, a large number of tile factories and a number of major industries, such as an oil refinery, a 1000 MWe thermal power station, are being set-up near Mangalore. Nuclear power reactors with a total capacity of 1410 MWe are coming up at Kaiga about 250 km north of Mangalore. In view of these industrial endeavours, a study of background radiation level and distribution of 31
32
A. P. Radhakrishna
et al
-55’
78
1L5-.;-
\
\
\
L
0
LKM
3O 0’
z 6
f
lil 4 cc 4
5’
\
B C ROAC
CL-’
0
0 7 1
n
NANOIKUR
PROPOSED THERMAL POWER STATION
A
MANGACA
CHEMICAL
l
KUDREMUKH
IRON
FERTILISER OR I’
Fig. 1. Area under investigation.
radionuclides in the environment of the region was carried out and baseline data have been evaluated to facilitate future impact assessment studies.
MATERIALS
AND METHODS
Sample processing
Natural samples of soil, sand, milk, rice, fish (marine), and varieties of vegetables were collected during 1988-1992 from Mangalore and the
Distribution qf‘natural and artijkial radionuclides in South India
33
surrounding area. All food items were directly collected from the farmers living in normal background area. Samples were preprocessed by following the standard methods (EML Procedures Manual, 1983). The collected samples were dried in an oven at 110°C. Except for soil and sand, the dried samples were charred under a low flame and converted into uniform white ash in a muffle furnace at 400-45O”C. Activity determination
The activity of 226Ra was estimated by the emanometry method where the samples were brought into solution form by leaching with HNOR and stored in the bubbler for sufficient buildup of radon activity. After radon was transferred to a scintillation cell from the bubbler, the cell was connected to a photomultiplier tube and then cl-activity was counted in an a-counting system (Iyengar et al., 1980). The activity of 228Ra was determined radiochemically. The activity of 228A~, the daughter of “‘Ra, was separated and 228Ra fraction was kept for a minimum of 30 h so as to reach equilibrium with its daughter and then counted in an argon gas flow type P-ray counter which had l-2 cpm background and 40% counting efficiency (Iyengar et al., 1990). The radiochemical method was also used to determine 2’0Pb activity. Here 210Bi, the daughter of 210Pb was separated from the sample solution and the 2’oPb fraction was kept for equilibrium with 2’oBi. Finally, it was separated as bismuth phosphate and counted in a low background /?-ray counter (Iyengar et al., 1990). The electrochemical deposition method was used for the measurement of 2roPo (Khandekar, 1977; Iyengar et al., 1990). About 20g of the dry sample were leached with HN03 + H202 and then converted into 0.5 M HCl solution. The solution was kept in a water bath at 90°C and 2’0Po was spontaneously plated by electrochemical displacement onto a silver disc. The disc was washed with distilled water, rinsed with alcohol, dried under an infrared lamp and the a-activity was counted in a ZnS(Ag) scintillation counter of 0.1 cpm background and 30% counting efficiency. Appropriate corrections for the growth of 2’oPo from “‘Pb and also for the decay of “‘PO were applied. Caesium- 137 and 9”Sr activities were measured by using the radiochemical method (Iyengar et al., 1990). Caesium-137 was separated as Cs2SnCld by using a Cs carrier and counted in a P-ray counter. To determine the activity of 90Sr, its daughter, 9oY, was separated and the “‘Sr fraction was kept for the equilibrium build up with 9oY. 9oY was finally separated as yttrium oxalate and counted in a b-ray counter. The activity of 40K was measured by employing y-ray spectrometry
34
A. P. Radhakrishna
et al.
method (Ramachandran & Mishra, 1989). The t-ray spectrometer consisted of a 10 x 10 cm NaI(T1) well-type crystal (M/S Harshaw Inc.) coupled to a 4K-channel pulse-height analyser. The detector was enclosed in a massive lead shielding of 15 cm thick lead blocks, lined with cadmium and copper sheets to reduce the intensity of lead X-rays. The spectrometer was calibrated using the standard sources of ‘37Cs, 40K, 226Ra and Th. The counting efficiency of the spectrometer in the 40K region was 15%. Ashed samples were filled in a 2 cm dia x 8 cm height plastic vial up to the top and kept inside the detector and counted for 50 000 s. The processing and counting of the environmental samples were carried out in the Environmental Survey Laborator, Kalpakkam, established by the Department of Atomic Energy, Government of India. The overall accuracy of different procedures was continually monitored in this laboratory by analysing periodically standardised matrices containing certified analytes provided by international agencies such as IAEA and the results are ascertained to be in agreement with certified values.
RESULTS AND DISCUSSIONS Radium-226 activity
In Table 1 the results are given of the activity of 226Ra and are compared with reported values for other environments. It can be seen that 226Ra activity is relatively high in soil and sand samples. Among the soil and sand samples, the activity is higher in soil samples, especially for the Ullal beach area, where the presence of monazite patches has already been reported (Radhakrishna et al., 1993). Mishra and Sadasivan (1971) analysed a large number of soil samples of different places in India by y-ray spectrometry and reported the 226Ra activity to be in the range of 2.59-26.3 Bq kg-’ with a mean value of 14.7 Bq kg-‘. The results obtained in the present work compare well with these literature values. The 226Ra activity in milk samples fall well within the range reported by Maul and O’Hara (1989). The activities in fish samles are comparable with reported values for Bombay, Kalpakkam, Italy, USA and other environments. The 226Ra activity in rice samples is comparable with reported values for other environments. The observed 226Ra activity in vegetable samples is comparable with reported values for some other areas of the world, but smaller compared to the reported values for Chavra in Kerala, Ramsar in Iran, and Black Forest in Germany. From the geometric mean values of 226Ra in soil and vegetables, the
Distribution qf’natural and artificial radionuclides in South India
35
soil-to-plant transfer coefficients (the ratio of activity concentration in plant to that in soil) were estimated. The transfer coefticients for vegetables was found to be 4 x IO-” and for rice 7 x IO-‘. The relatively higher values for rice may be due to the longer growing period of the paddy. This fact incidentally confirms the earlier findings, viz. the uptake of the radionuclides by plants depend upon soil characteristics, climatic conditions, type of plants, physical and chemical properties of radionuclides (Bettencourt et al., 1988). The transfer coefficients of ‘lhRa for vegetables reported in the literature are in the range of 0.07 x lo-‘-0.75 (Bettencourt et al., 1988). Paul and Pillai (1986) carried out an extensive investigation on uptake of 226Ra and 228Ra by rice and a variety of vegetables in Kerala and reported transfer coefficients are in the range of 4.2 x 10e3-0.36. Thus the values obtained in the present work are well within the range reported in the literatures. Lead-210 activity In Table 2 the results are given of 210Pb activity in various samples of Mangalore environment. It may be seen that both in soil and sand samples of high background area of Ullal beach 2’0Pb activity is considerably high. Fish samples show considerably higher activity of 2’0Pb. The activity in the rice sample is comparable to that of the Bombay samples. In vegetables, the activity is low compared with that of Kalpakkam and Black Forest of Germany. The activity of 2’0Pb in milk samples is higher compared to the literature values for different parts of the world. The 2’oPb in plants may come from fallout, and also from the root uptake (Jaworowski, 1967). The average soil-to-plant transfer coefficients were estimated for rice and vegetables using the average activity in soil and in the corresponding samples and were respectively found to be I .2 x lo-’ and 7 x 10-j. As in the case of “26Ra, a higher uptake was observed in rice compared to vegetables. Polonium-210
activity
Polonium-210 activity results are given in Table 3. The activities are relatively higher in soil and sand samples. The activity in samples from the monazite area of Ullal is quite high. The 2’oPo in soil is produced due to the decay of radionuclides of the uranium series present in the soil or due to the precipitation of radon decay products from the atmosphere. The ““PO content of the soil varies widely (8.14219 Bq kg-‘) depending upon the soil structure (Parfenov, 1974). Next to soil, fish samples show higher activity. The higher 2’oPo activity in fish samples was also observed in
Fish [S]
Milk /5 J
Sandd [2/
0.08-0.27 (0.12)
(3.6) 466-50.9 (48.7) BDL’-0.08 (0.03
84.2-120.5 (102.4) 2.8-4.9
Soil” [3/
Sand [4/
3.1-15.9 (il.l)h
Present work
Soil [8 /
Sample
Activity
Kalpakkam USA Italy World range
BDL-0.2 0.033 0.052-O. 12 0.007-0.2
All India Kalpakkam Bombay Ireland Black Forest Kerala Ramsar, Iran Kalpakkam
Samples
Kalpakkam Kerala Italy Italy USA World range Black Forest Bombay
values
Region
TABLE 1 Activity in Different
170-347.8 1011 0.003-0.02 0.007 0.009 0.03-O. 1 0~0041~78 0.32-0.62
2.59-26.3 9.25 3.33-18.5 I O-200 l3&48~1 7.8-1520” 740-3700“ 4.81
Literature
(Bq kg -‘j
Radium-226
Rajan et al. (1987) Fisenne and keller ( 1970) de Bortoli and Gaglione (1972) Maul and O’Hara (1989)
Iyengar et al. (1980) Lalit and Shukla (1982) Mastinu and Santaroni (1980) de Bortoli and Gaglione (1972) Morse and Welford (1971) Maul and O’Hara (1989) Schuttelkopf and Kiefer (1982) Ramachandran and Mishra (1989)
Mishra and Sadasivan (1971) Iyengar et al. (1980) Lalit and Shukla (1982) McAulay and Moran (1988) Schuttelkopf and Kiefer (1982) Kamath et al. (1964) Khademi et al. (1980) Iyengar et al. (1980)
Reference
.-
BDL-0.12 (0.04)
Vegetables [IO]
0~04-0~07
BDL BDL-0.1 0~01-0~30 0.03 0.2 0.02-0.3 BDL4.78” BDL-0.06 0.13-2.21d 0.04-6.29 0~01-0~04 0.056
Kalpakkam Kalpakkam Bombay USA World range Kalpakkam Kerala Bombay Ramsar, Iran Black Forest Italy USA World range
Iyengar et al. (1980) Rajan et al. (1987) Ramachandran and Mishra (1989) Morse and Welford (1971) Maul and O’Hara (1989) Rajan et al. (1987) Lalit and Shukla (1982) Lalit and Shukla (1982) Khademi e? al. (1980) Schuttelkopf and Kiefer (1982) de Bortoli and Gaglione (1972) Fisenne et al. (1987) Maul and O’Hara (1989)
“The numbers given in the square bracket indicate the number of samples analysed. ‘When the number of samples is 3 or more than 3 the geometric mean value is calculated and when it is less than 3, the arithmetic mean value is calculated. These values are reported in parentheses. ‘If the net sample count of the sample is less than twice the square root of the standard deviation of counter background, the activity reported as BDL (below detectable limit). “High background area in Ullal. The same nomenclature is followed in Table 2-7.
BDLO.09 (0.08)
Rice [S]
.I
w
8 5 ;5
Q. 6’ z r?. fi: 2 _. 3
& K’ -. 2
2 %
2
2
B 2
5 B z 2. 2
P
Sand (41
0.49-l .72 (1.05)
0.06-0.23 (0.09)
Fish [5/
Vegetables [IO]
Rice [5/
Milk (51
Sand” [2/
BDL@75 0.13 0,2 0.11 0.12-1.65 0.04 0.05 0.5631.82
0.03 0.01 0.13 0.03-0.48 0.14 0.033
384.8
(118) 2.9-4.4
Soild [3]
(3.8) 9x-141.3 (118.5) BDL-0.07 (0.04) BDL-0.39 (0.16)
22.2-122.1
3&45.2 (13,3) 89.7-146.4
Soil [8/
Literature values
Activity iBq kg~-‘j
Samples
Kalpakkam USA World range Bombay Kalpakkam USA UK Black Forest
UK USA Bombay Bombay Kalpakkam USA
Kalpakkam
-
Black Forest
Region
TABLE 2 Activity in Different
Present work
Sample
Lead-210
et al. (1980)
Iyengar et al. (1980) Morse and Welford (1971) Maul and O’Hara (1989) Ramachandran and Mishra (1989) Iyengar et al. (1979) Morse and Welford (1971) Maul and O’Hara (1989) Schuttelkopf and Kiefer (1982)
(1989)
and Kiefer (1982)
Maul and O’Hara (1989) Morse and Welford (1971) Ramachandran and Mishra Lalit et al. (1980) Iyengar et al. (1980) Morse and Welford (1971)
Iyengar
Schuttelkopf
Reference
8 s 2 R P r
$ F
s
b
E
Vegetables (IO]
Fish IS/
Rice (51
Milk (5 /
Sand” (41
Sand [4]
Soild (51
Soil [8/
Sample
(2.0) BDL-0.20 (0.06)
BDL-0.24 (0.16) 0.2 I-3.7
(1.7) 24.240.1 (37.1) BDL-0.019 (0.010)
(9.5) 2 1659.6 (24.7) 1.6-2.7
1.3-13.7
Present work
Activity
Samples
Bombay World range World range Kalpakkam Bombay Kalpakkam World range Bombay Kalpakkam Black Forest
Kalpakkam
Kalpakkam Black Forest World range
Region
TABLE 3 10 Activity in Different
values
0.015 0.02-0.2 0~003-0~018 0.1-0.5 0.12 0.98-24.6 6 0.016-0.4 BDL-O.2 0.33-l ,63
44.4
44.4 33.3-207.2 814-219
Literature
(Bq kg-‘)
Polonium-2
et al. (1980) Khandekar (1977) Maul and O’Hara (1989) Parfenov (1974) Rajan et al. (1987) Khandekar (1977) Iyengar et al. (1980) Maul and O’Hara (1989) Khandekar (1977) Rajan et a. (1987) Schuttelkopf and Kiefer (1982)
Iyengar
-
Iyengar et al. (1980) Schuttelkopf and Kiefer (1982) Parfenov (1974)
Reference
40
A. P. Radhakrishna et al.
other environments (Holtzman, 1969; Khandekar, 1977; Iyengar et af., 1980; Rajan et al., 1980; Horsic & Bauman, 1982). Plankton present in sea water accumulate some kinds of radionuclides very rapidly and retain them for a long time, which leads to a considerable degree of selective concentration of the radionuclides from the sea water (Parfenov, 1974). These plankton are the main food for marine species. Most of the 210PO content in the plants is the result of direct deposition of radon daughter products on the leaf of plants from the atmospheric precipitation. Apart from this the accumulation of 2’oPo by vegetables depends on their morphological aspects and on plant age as well as on external factors such as soil type, chemical fertilizers, frequency of precipitation and density of aerosols (Santos et al., 1990). Only in root vegetables is the uptake of 2’oPo from the soil exclusively. In the present work no root vegetables were analysed. Hence the soil-to-plant transfer coefficients for 210Po were not estimated. In order to tind out whether or not the parent and daughter nuclides are in equilibrium, the average activity ratios of 2’oPo : 210Pb were estimated. In normal soils of Mangalore, the result was found to be 0.71 suggesting that 210Po is partially in equilibrium with 2’0Pb. The activity ratios reported in the literature are in the range of 0.75-0.82 (Parfenov, 1974). On the other hand, in high background areas, they are not in equilibrium. Lead-210 activity is about 5 times higher than 2’oPo activity. The 210: 2’0Pb ratio depends on: (i) duration of 2’0Pb existing within a matrix; and (ii) whether polonium is selectively removed from its site of production by chemical or biological means (Eisenbud, 1987). In the high background area of Ullal beach, the continuous deposition of the monazite by sea wave actions, the turbulent wind blowing constantly from the sea and also the effective sequestering of 210Pb by the organic matter of the soil may be responsible for the observed disequilibrium between 210Po and 2’0Pb. The measured “‘PO activity in milk samples of Mangalore is comparable with the reported values for Bombay and the world range. The average activity ratio of 2’oPo : 210Pb in milk samples is 0.25, lower than the reported values 0.4-0.8 (Parfenov, 1974). In rice and vegetables, the average activity ratio is I.0 and 0.67, respectively. It was reported that as the growing period of the plant increases, the ratio is tending to unity (Parfenov, 1974). The result obtained for rice in the present work substantiates this viewpoint. In fish samples the average activity ratio was found to be I.90 and lies on the lower side of the range of 1.8-12.4 reported by Parfenov (1974). The observed wide variation is due to the various environmental factors which influence the concentrations of 210Po as well as 210Pb in the environment.
Distribution of natural and art$cial radionuclides in South India
41
Radium-228 activity In Table 4 the 228Ra results are given. It is clear that 228Ra activity is significantly high in monazite soil and sand samples. However, it is low compared to the literature values reported for samples of Kalpakkam monazite area (Iyengar et al., 1980). The activity in rice and vegetable samples of Mangalore environment is low compared to the activity in corresponding samples from Kalpakkam, Kerala and Brazil which are monazite areas. The average soil-to-plant transfer coefficient was estimated using the geometric mean value presented in Table 4. The transfer coefficients are 0.017 and 0.028 in vegetables and rice. Both in 226Ra and 22sRa the transfer coefficients from soil-to-plant area lower than unity, showing that plants are not preferential to pick-up of Ra, even though Ra is chemically similar to Ca. The transfer coefficients for 226Ra is an order of magnitude lower than that for *‘sRa, which indicate the preferential transfer and uptake of 228Ra and support the earlier observations of Paul and Pillai (1986). Using the geometric mean activity of 228Ra (Table 4) and 226Ra (Table 1) in soil and sand samples, the activity ratios of 228Ra: 226Ra were estimated. In the normal background radiation of Mangalore, the ratio is nearly unity in soil and sand samples. However, in Ullal beach soil, the ratio is 2.2 and in sand it is 3.8. It is reported that the activity ratio of 228Ra : 226 Ra in normal soil is nearly 1 (Eisenbud, 1987). In Kalpakkam monazite samples the reported ratio is 3615.3 and in Brazil it is 6 (Iyengar, 1989). Since monazite contains more 232Th and 228Ra belonging to Th series, its activity is more than 226Ra and the observed trend clearly reflects this fact. Potassium-40 activity The y-ray spectrometry results for 40K activity are given in Table 5. The number of samples analysed is one in each case and the activity is presented with the standard deviation of counting statistics. It can be seen that the 40K activity in soil samples is comparable with that of Kudankulam environment, but low compared to that of other areas of the country as well as outside the country. The activity is also low compared to the world range (UNSCEAR, 1982). In milk samples the activity is comparable to the result reported for the Kudankulam and Kerala areas, but higher compared to the reported world range. More extensive investigations are needed to understand the relatively higher activity present in milk. The activities in rice, fish and vegetable samples are either comparable with literature values reported for other environments or lower.
42
A. P. Radhakrishna et al
108 i 22.6
71.9*0.7
59.6 + 0.6
79.2 i 0.6
70.9 i 0.5
70.8 i 0.5
85.2 & 0.4
68.2 i 0.6
Milk
Rice
Fish
Vegetables Cucumber
Brinjal
Spinach
Ladies Finger
Present work
Soil
Sample
12k-632 9.6240.7 34.78-245 2&146 1036 350 103-1362 10~700 (370) 670-1000 87 46.7698.87 40 62 55.5-86.6 44.488.8 31.5-88.7 17.4-46.3 76.2-129.2 72.2-98.86 90 4g-240 79.4 9.6-37 33.9 108.8, 64.7 33.9 91.4136.9 75.9-242 X1.4218.3 104 20. 6.3, 60.7
Samples
World range Kerdla Kerala Kerala Kerala Kerabd Bombay Bombay Bombay Bombay Kerala
Kalpakkam Bombay Bombay Kudankulam Maryland, USA Ireland Kerala World range Finland Kudankulam Kerala World range World range Bombay Bombay Kerala Kerala Bombay Kerala
Region
TABLE 5 Activity in Different
Literature values
Activity (Bq kg-‘)
Potassium-40
Kannan et al. (1992) Kamath et ul. (1964) Lalit and Shukla (1982) Lakshmi (1990) Pinkerton et al. (1964) McAulay and Moran (1988) Lalit and Shukla (1982) UNSCEAR (I 982) Klemola et al. (1991) Lakshmi (1990) Mistry et al. (1970) Maul and O’Hara (1989) Maul and O’Hara (1989) Ramachandran and Mishra (1989) Lalit and Shukla (1982) Lalit and Shukla (1982) Mistry et al. (1970) Ramachandran and Mishra (1989) Mistry et al. (1970) Maul and O’Hara (1989) Maul and O’Hara (1989) Mistry et al. (1970) Lalit and Shukla (1982) Lalit and Shukla (1970) Lalit and Shukla (1982) Mistry et al. ( 1970) Lalit and Shukla (1982) Ramachandran and Mishra (1989) Lalit and Shukla (1982) Lalit and Shukla (1982) Lalit and Shukla (1982)
Reference
44
A. P. Radhakrishna et al.
Strontium-90 activity The results obtained for ?Sr activity are given in Table 6. It can be seen that 90Sr activity in all the samples of Mangalore area is, in general, low compared to the reported values for other environments. The activity of 90Sr in soil and milk samples is close to BDL. Strontium-90 activity in fish samples of Mangalore is low compared with the values reported for Kalpakkam environment. Caesium-137 activity Table 7 contains the results of 13’Cs activity. It is interesting to note that compared to 90Sr activity, ‘37Cs activity is present in appreciable amounts in samples from Mangalore. The activity in soil samples of Mangalore is lower than that of Kalpakkam and is comparable with activity for the Bombay and Hawaii areas. The ‘37Cs activity in soil samples of Mangalore is low compared to Finland, Greece and Japan. These findings indicate that fallout activity due to the Chernobyl accident has not reached the Indian environment significantly. Caesium-137 is chemically similar to potassium and is therefore ingested quantitatively when taken into the animal body through food, and excretion of 137Csthrough the milk is very rapid because its biological half-life in a cow is only 20 days (Vohra et al., 1961). Furthermore, milk is one of the common items of food of all sections of the people. Hence, the estimation of ‘37Cs in milk is important to assess the internal dose. Vohra et al. (1961) reported ‘s’Cs activity in milk samples of different patrts of India. The values obtained in the present work for milk samples of Mangalore fall in the lower range of values reported by Vohra et al. (1961). The higher values reported correspond to the activity measured in 1961, the period in which a large number of atmospheric nuclear weapon tests were conducted in various countries and the fallout of ‘37Cs was maximum. It can also be seen from Table 7 that ‘37Cs activity in rice samples of Mangalore is low compared to the activity reported for Kalpakkam environment. In vegetable samples, the activity is comparable with that of Kalpakkam and is relatively higher compared to Bombay, while the activity is low compared to Japan and Finland. In fish samples the activity in Mangalore is lower compared to Kalpakkam and Japan and it is very low compared to the activity in fish samples of Finland. Internal dose Using the results of average activities of rice, milk, fish and vegetables presented in Tables 1-7 and the data on food consumption pattern
BDL-0.15 (0.05)
BDL-0.04 (0.03)
BDL-0.23 (0.08)
BDL-0.20 (0.03)
Fish (41
Rice [S]
Vegetables [IO]
(0.4)
BDL-0.75
Present work
Milk [S /
Soil /4]
Sample
Activity
Samples
Japan Finland Kalpakkam Kalpakkam Austria Bombay Japan Finland Taiwan Japan Kalpakkam New York Kalpakkam Japan New York Kalpakkam New York
Region
TABLE 6 Activity in Different
values
0.1-13 3.6-34 BDL-6.67 0.02ZO.17 0.33 0.1 l-0.16 0~0160~28 0.12-0.13 0.31 BDL-0.053 0.08-0.26 0.0074, 0.026 < 0.02-0.6 BDL-0.08 0.022 0.040.35 0.33
Literature
(Bq kg-‘)
Strontium-90
NIRS (1990) Klemola et al. (1991) Iyengar et a/. (1979) Rajan et al. (1987) Muck et al. (1990) Hingorani et al. (1976) NIRS (1990) Klemola et al. (1991) Chien (1989) NIRS (1990) Rajan et al. (1987) Eisenbud (1987) Rajan et al. (1987) NIRS (1990) Eisenbud (1987) Rajan et al. (1987) Eisenbud (1987)
Reference
0.051-0.43 (0.093) BDL-0.32 (0.14)
BDL-0.30 (0.18)
Rice ./5 _1
Vegetable [IO]
(1963)
Rajan ef al. (1987) NIRS (1990) Eisenbud (1987) Hasanen and Miettinen Klemola et al. (1991) Shukla et al. (1987) Rajan et al. (1987) Eisenbud (1987) Klemola ef al. (1990) NIRS (I 990) Chien (1989) Kalpakkam Japan New York Finland Finland Bombay Kalpakkam New York Finland Japan Taiwan
< 0.08-2.5 0.012-0.49 7.2 23.7-218 4.6-200 0.15-0.27 0.04-0.27 0.074 0.48-0.69 BDL-0.82 3.1
BDL-0.14 (0.06)
Milk [Sj
Fish [S]
Rao et al. (1983) Iyengar et al. (1979) Shukla et al. (1987) Cox and Fankhauser (1984) NIRS (1990) Papastefanou et al. (1988) Klemola et al. (1991) NIRS (1990) Eisenbud (1987) Vohra et al. (1961) Rajan et a/. (1987) Klemola et al. (1991) Chien (1989) Ward et al. (1989) Rajan et al. (1987)
Bombay Kalpakkam Bombay Hawaii Japan Greece Finland Japan New York All India Kalpakkam Finland Taiwan Hungary Kalpakkam
< 1.18 BDL-14.43 5.2-9.5 1.5-71.4 0.6-98 291-7671 22-6700 BDL-0.65 0,67 0.1 l-9.69 0.02-0.56 8.7 0.31 6.696 <0.02-1.31
Reference
BDL-7.4 (1.66)
values
Region
Soil [ 7/
(By kg-‘)
Samples
Literature
Activity
TABLE 7 Activity in Different
Present work
Sample
Caesium-137
Distribution of natural and artjficial radionuclides in South India
47
reported in Diet Atlas of India (ICMR, 1971). the intake of radionuclides by the population of Mangalore was estimated. The results are presented in Table 8. It can be seen from the table that the average daily intake of 40K is the maximum. However, it causes no concern because as an isotope of an essential element for metabolic activity, it is homeostatically controlled in the body (Holtzman, 1980). Next to 40K, the intake of 2’oPo is relatively more. The contributions from *“Pb and 22*Ra are also considerable. It may be noted that the major share of intake of both *“Pb and 210Po comes from fish (Tables 2 and 3). Literature values reported for other environs of the country/world are also presented in Table 9 for comparison. Using the activity intake results presented in Table 9, the annual effective internal dose due to the ingestion of different radionuclides is calculated. The results are given in Table 10. The corresponding conversion factors used to evaluate the internal doses are also given in the table. The literature values reported for other environs are given in column 4 for comparison. It is clear from columns 3 and 4 that the effective dose equivalents to the population of Mangalore area due to 226Ra and ‘j7Cs are comparatively low, that due to *“Pb is almost the same, due to 40K is comparable and due to 228Ra is relatively high. The percentage contributions for the cumulative dose from the individual radionuclides are given in the last column of the table. The population of Mangalore and surrounding regions covered under the present investigation is about 700000. The total internal dose for this population is estimated by adding the effective dose equivalent from different radionuclides (column 3, Table 10). The internal dose for the population of Mangalore is estimated to be 341 ,&v year-‘.
ACKNOWLEDGEMENT The authors would like to thank Dr D. V. Gopinath, Former Director, Health, Safety and Environment Group, BARC, Bombay, for his encouragement. The authors would like to express their special thanks to Dr M. A. R. Iyengar, Head, ESL, Kalpakkam, for many helpful suggestions and the assistance received from his colleagues. The authors acknowledge the helpful assistance of Dr K. M. Balakrishna and N. Karunakara, Department of Physics, Mangalore University. The authors are grateful to the Board of Research in Nuclear Sciences, Department of Atomic Energy, Government of India for sponsoring the research project.
Dail) in take (kg)
0.36 0.1 0.10 0.05
Food item
Rice Milk Fish Vegetables Total:
0.029 0.003 0.012 0.002 0.046
226 Ra
The Estimated
0.058 0.004 0.105 0.004 0.171
“OPb 0.058 0.001 0.20 0.003 0.262
2’oPo 0.090 0.019 0.050 0.007 0.166
“‘Ra
Dai!,l intake qfuctivity
21.60 7.19 7.92 3.9 40.61
40K
(Bq day-‘)
TABLE 8 Daily Intake of Main Food Items and Activity
0.029 0.005 0.003 0.001 0.038
9”Sr
0.032 0.006 0.014 0.009 0.061
‘37cs
a 2 Pr
$j
a 3a B $
b
l"lcs
40K “Sr
22SRa
‘lop0
*“Pb
226Ra
Radionuclide
0.06
40.6 0.04
0.166
0.262
0.171
0.046
Present work
TABLE 9
0.13 0.074 0.11 0.027 0.067 0.05 1 0.065 0.374.14 0.13 0.13 0.05 0.32 0.06 0.15 2.55 5.92 0.26, 5.2 0.56 0.7488 79.4 0.04-0.32 0.096 2.0 0.040~7 1.25
Reported values
Daily intuke (Bq da-v-‘)
Daily Intake of Radionuclides
Bombay Kalpakkam Kerala Bombay USA USA UK Brazil Bombay Bombay USA Finland Bombay Erstwhile USSR Finland Kerala Kerala Kalpakkam Brazil Bombay Kalpakkam New York San Francisco Kalpakkam Chicago
Region
in Different Regions
Ramachandran and Mishra (1989) lyengar et al. (1978) Chabra (1966) Chabra (1966) UNSCEAR (1982) Holtzman (1980) UNSCEAR (1982) Penna-Franca et al. (1970, 1972) Ramachandran and Mishra (1989) Lalit and Shukla (1981) Morse and Welford (1971) Kauranen and Miettinen (1969) Khandekar (1977) Ladinskaya et al. (1973) Kauranen and Miettinen (1969) Mistry et al. (1970) Paul et al. (1982) Iyengar (1989) Penna-Franca et al. (1972) Ramachandran and Mishra (1989) Rajan et al. (1987) Eisenbud (1987) Eisenbud (1987) Rajan et al. (1987) Eisenbud (1987)
Reference
180
122
0.7
0.4
3h
0.05”
0.02”
40K
u,& Bq-’ (ICRP, 1978). ‘@v year-‘/Bq day-’ (NCRP, “UNSCEAR (1988).
13’cs
1987).
13
60 29
0.63” 0.48”
2’oPo 22sRa
260 2.1-190 I.5514
1.8760
120
122
1.96”
“‘Pb
90Sr
65-250
Literature’ values
I
Present work
background
Europe Erstwhile USSR Asia North America
of the world Normal background of the world -
Normal
Araxa-Tapira Normal background of the world
Environ
Effective dose equivalent (ptsv year-‘)
with Other Environs
TABLE 10 and Comparison
0.43”
Dose conversion factors
Mangalore
226~~
Radionuclide
The Estimated
areas
areas
areas
by the Population
0.1
0.2
36
2 %+ a &‘. B g I P; .-
b 18 8
b 2
of
36
Percentuge of contribution (present work) (%)
Radionuclides
Distribution of natural and ar@cial radionuclides in South India
51
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Iyengar, M. A. R., Bhat, I. S. & Kamath, P. R. (1979). Progress Report of Environmental Survey Laboratory, Kalpakkam (1974-78) BARC/I-536. lyengar, M. A. R., Rajan, M. P., Ganapathy, S. & Kamath, P. R. (1980). Sources of natural radiation exposure in a low monazite environment. In Natural Radiation Environment III, Proceedings of ht. Conference, CONF-780422, ed. T. F. Gesell & W. M. Lowder, Vol. 2, pp. 1090-106. Iyengar, M. A. R., Ganapathy, S., Kannan, V., Rajan, M. P. & Rajaram, S. (1990). Procedure
Manual,
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Radioactivity,Kaiga,
India, 16-18 Apr. Jaworowski, Z. (1967). Stable and Radioactive Lead in Environment and Human Body. Nuclear Energy Centre, Warsaw, Poland. Kamath, P. R., Khan, A. A., Rao, S. R., Pillai, T. N., Borkar, M. L. & Ganapathi, S. (1964). In The Natural Radiation Environment I, ed. J. A. S. Adams & W. M. Lowder, University Chicago Press, Chicago, pp. 957-78. Kannan, V., Rajan, M. P. & Iyengar, M. A. R. (1992). Gamma spectrometric studies of beach sands and soils in the enhanced background site at Kalpakkam. National Seminar on Radiation Environment and Man, Mysore University, Mysore, India, 8-9 Oct. Kauranen, P. & Miettinen, J. K. (1969). PO-210 and b-210 in the arctic food chain and the natural radiation exposure of Lapps. Health Phys., 16, 287-96. Khademi, B., Alemi, A. A. & Nasseri, A. (1980). Transfer of radium form soil to plants in an area of high natural radioactivity in Ramsar, Iran. In Natural Radiation Environment III, Proceedings qf Int. Conference, CONF-780422, ed. T. F. Gesell & W. M. Lowder, Vol. 2, pp. 600-10. Khandekar, R. N. (1977). Polonium-210 in Bombay diet. Health Phys., 33, 1_5&4. Klemola, S., Ilus, E., Sjoblom, K. L., Arvela, H. & Blomqvist, L. (1991). Monitoring of Radionuclides in the Environs of the Finish Nuclear Power Stations in 1988. STUK-A92. Ladinskaya, L. A., Parfenov, Y. D., Popov, D. K. & Fedorova, A. V. (1973). Pb210 and PO-210 content in air, water, foodstuffs and the human body. Health Phys., 21, 244-58.
Lakshmi, K. S. (1990). A Report on the Background Radiation Survey at Kudankulam Project Site and its Environs, Part-II. Spectral Measurements and Analysis of Soil, Terrestrial, Marine and Diet Samples. Meenkshi College for Women, Madras, India. Lalit, B. Y. & Shukla, V. K. (1982). Natural radioactivity in food stuffs from high natural radioactivity areas of southern India. In Proceedings of 2nd Special Symposium on Natural Radiation Environment, ed. K. G. Vohra, U. C. Mishra, K. C. Pillai & S. Sadasivan. Wiley Eastern, New Delhi, pp. 43-9. Lalit, B. Y., Ramachandran, T. V. & Rajan, S. (1980). Pb-210 content of food samples in India. Radiat. Environ. Biophys., 18, 13-7. Linsalata, P., Morse, R. S., Ford, H., Eisenbud, M., Penna-Franca, E., de Castro, M. B., Lobao, N., Sachett, I. & Carlos, M. (1989). An assessment of soil to plant concentration ratios for some natural analogues of the transuranic elements. Health Phys., 56, 33-46. Mastinu, G. G. & Santaroni, G. P. (1980). Radium-226 levels in Italian drinking water and foods. In Natural Radiation Environment III, Proceedings qf Int. Conjbence, CONF-780422, ed. T. F. Gesell & W. M. Lowder, Vol. 2, pp. 810-2.5.
Distribution of natural and artificial radionuclides in South India
53
Maul, P. R. & O’Hara, J. P. (1989). Background radioactivity in environmental materials. J. Environ. Radioactivity, 9, 265-80. McAulay, I. R. & Moran, D. (1988). Natural radioactivity in soil in the Republic of Ireland. Radiat. Prot. Dosi., 24, 47-9. Mishra, U. C. & Sadasivan, S. (1971). Natural radioactivity levels in Indian soils. J. Sci. Indust. Res., 30, 59-62.
Mistry, K. B., Bharatan, K. G. & Gopal Iyengar, A. R. (1970). Radioactivity in the diet of population of the Kerala coast including monazite bearing high radiation areas. Health Phys., 19, 53542. Morse, R. S. & Welford, G. A. (1971). Dietary intake of Pb-210. Health Phys., 21, 53-5.
Muck, K., Streit, S., Steger, F. & Mayar, M. (1990). Estimate of the dose due to Sr-90 to the Austrian population after the Chernobyl accident. Health Phys., 58,47-g
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Council on Radiation
Protection
Exposure of the population in the United States background radiation. Report No. 94.
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and Canada from
natural
NIRS (1990). Radioactivity Survey Data in Japan, NIRS-RSD-90 & 91. National Institute of Radiological Sciences, Chiba, Japan. Papastefanou, C., Manolopoulou, M. & Charalambous, S. (1988). Cs-137 in soils from Chernobyl fallout. Health Phys., 55, 985-7. Parfenov, Y. D. (1974). PO-210 in the environment and in the human organism. Atomic
Energy Rev., 12, 75143.
Paul, A. C. & Pillai, K. C. (1986). Transfer and uptake of radium in natural and technologically modified radiation environment. J. Environ. Radioactivity, 3, 55-73.
Paul, A. C., Pillai, P. M. B., Velayudhan, T. & Pillai, K. C. (1982). Internal exposure at high background areas. In Proceedings of 2nd Special Symposium on Natural Radiation Environment, ed. K. G. Vohra, U. C. Mishra, K. C. Pillai & S. Sadasivan. Wiley Eastern, New Delhi, pp. 50-7. Penna-Franca, E., Fiszman, M, Lobao, N., Trindade, H., Costa-Ribeiro, C. & Santos, P. L. (1970). Radioactivity in the diet in high background areas of Brazil. Health Phys., 19, 657-62. Penna-Franca, E., Coasta-Ribeiro, C., Cullen, T. L., Barcinski, M. & Gonzalez, D. E. (1972). Natural radioactivity in Brazil, A comprehensive review with a model for dose effect studies. In The Natural Radiation Environment II, Proceedings of Symposium on Natural Radiation Environment, Houston, TX, pp. 92940. Pillai, T. N. V. & Kamath, P. R. (1966). Radioactivity measurement in environmental samples in monazite areas. Proceedings qf Symposium on Radioactivity and Metrology of Radionuclides, BARC, Bombay, India, pp. 27486. Pinkerton, C., Chen, W. Y, Hutchins, R. G. & Schrohenloher, R. E. (1964). Background radioactivity monitoring of a pilot study community in Washington county, Maryland. In The Natural Radiation Environment I, ed. J. A. S. Adams & W. M. Lowder. University Chicago Press, Chicago, pp. 919-56. Radhakrishna, A. P., Somashekarappa, H. M., Narayana, Y. & Siddappa, K. (1993). A new natural background radiation area on the south west coast of India. Health Phys., 65, 390-5.
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Rajan, M. P., Kannan, V., Ganapathy, S. & Iyengar, M. A. R. (1980). Natural radioactivity intake through dietary sources at Kalpakkam. Bull. Radiat. Prot., 3, 69-74.
Rajan, M. P., Kannan, V., Ganapathy, S. & Iyengar, M. A. R. (1987). Radiation exposure estimates from natural and man made sources in environment of Kalpakkam. Seventh National Symposium on Radiation Physics, Mangalore, India, November 1620. Ramachandran, T. V. & Mishra, U. C. (1989). Measurement of natural radioactivity levels in Indian food stuffs by gamma spectrometry. Bull. Radiat. Prot., 12, 51-5.
Rao, S. R., Londhe, V. S. & Pillai, K. C. (1983). Low level radioactivity measurements using gamma ray spectrometry. Bull. Radiat. Prot., 6, 3341. Santos, P. L., Gouvea, R. C., Dutra, I. R. & Gouvea, V. A. (1990). Accumulation of ~0-210 in foodstuffs cultivated in farms around the Brazilian mining and milling facilities on Pocos de Caldas Plateau. J. Environ. Radioactivity, 11, 141-9.
Schuttelkopf, H. & Kiefer, H. (1982). The radium-226 and polonium-210 concentration of the Black Forest. In Proceedings qf 2nd Special Symposium on Natural Radiation Environment, ed. K. G. Vohra, U. C. Mishra, K. C. Pillai & S. Sadasivan. Wiley Eastern, New Delhi, pp. 194200. Shukla, V. K., Menon, M. R. & Lalith, B. Y. (1987). Environmental contamination from Chernobyl fallout. Bull Radiat. Prot., 10,93-6. UNSCEAR (1982). 32nd Session, SupplNo. 45 (A/37/45). United Nations Scientific Committee on the Effects of Atomic Radiation, United Nations, New York. UNSCEAR (1988). United Nations Scientific Committee on the Effects of Atomic Radiation, United Nations, New York, pp. 309-74. Vohra, K. G., Bhatnagar, V. S., Mishra, U. C. & Ragupathy, S. (1961). Measurement of Cs- 137 in milk. Health Phys., 6, 142-8. Ward, G. M., Keszthelyi, Z., Kanyar, B., Karalovanszky, U. P. & Johnson, J. E. (1989). Transfer of Cs-137 to milk and meat in Hungary from Chernobyl fallout with comparisons of world wide fallout in 1960s. Health Phys., 57, 587-92.
Copyright
0
Printed ELSEVIER
30 No. 1. pp. 31 54, 1996 1995 Elsevier Science Limited
in Ireland. All rights reserved 0265-931X/96 $15.00 $ 0.00
0265-931X(95)00037-2
Distribution of Some Natural and Artificial Radionuclides in Mangalore Environment of South India
A. P. Radhakrishna,
Department
H. M. Somashekarappa, & K. Siddappa
of Studies in Physics, Mangalore (Received
14 February
University, 1994; accepted
Y. Narayana
Mangaiagangotri
-
574 199, India
12 May 1995)
ABSTRACT The activities of 40K, 226Ra, 22XRa, “‘PO, 2’“Pb, J37CLsand”‘Sr were determined in a number of natural samples in the environment of Mangalore, South India where large-scale industrial activities are envisaged. Well-established nuclear techniques were employed to measure the activities and wherever necessary radiochemical methods were also followed. The measurement of transfer coef jicients indicated that the uptake ofZZ6Ra, 228Ra and “‘Pb in paddy is higher than that in vegetables. The measured activity ratios of “‘Po: ‘tOPb and 228Ra : 226Ra in soil samples suggest the existence of equilibrium between the corresponding radionuclides in normal background areas and disequilibrium in high background areas. The intake ofradionuclides by the population and the internal dose were estimated. The annual internal efjective dose,for the population is,found to be 341 uSv year-’ which mainly arises from 40K and ‘IoPb.
INTRODUCTION Mangalore city and the surrounding region (Fig. 1) on the west coast of India are on the threshold of becoming a major industrial area. In addition to the existing big chemical and fertilizer factories, an iron ore pelletisation plant, a large number of tile factories and a number of major industries, such as an oil refinery, a 1000 MWe thermal power station, are being set-up near Mangalore. Nuclear power reactors with a total capacity of 1410 MWe are coming up at Kaiga about 250 km north of Mangalore. In view of these industrial endeavours, a study of background radiation level and distribution of 31
32
A. P. Radhakrishna
et al
-55’
78
1L5-.;-
\
\
\
L
0
LKM
3O 0’
z 6
f
lil 4 cc 4
5’
\
B C ROAC
CL-’
0
0 7 1
n
NANOIKUR
PROPOSED THERMAL POWER STATION
A
MANGACA
CHEMICAL
l
KUDREMUKH
IRON
FERTILISER OR I’
Fig. 1. Area under investigation.
radionuclides in the environment of the region was carried out and baseline data have been evaluated to facilitate future impact assessment studies.
MATERIALS
AND METHODS
Sample processing
Natural samples of soil, sand, milk, rice, fish (marine), and varieties of vegetables were collected during 1988-1992 from Mangalore and the
Distribution qf‘natural and artijkial radionuclides in South India
33
surrounding area. All food items were directly collected from the farmers living in normal background area. Samples were preprocessed by following the standard methods (EML Procedures Manual, 1983). The collected samples were dried in an oven at 110°C. Except for soil and sand, the dried samples were charred under a low flame and converted into uniform white ash in a muffle furnace at 400-45O”C. Activity determination
The activity of 226Ra was estimated by the emanometry method where the samples were brought into solution form by leaching with HNOR and stored in the bubbler for sufficient buildup of radon activity. After radon was transferred to a scintillation cell from the bubbler, the cell was connected to a photomultiplier tube and then cl-activity was counted in an a-counting system (Iyengar et al., 1980). The activity of 228Ra was determined radiochemically. The activity of 228A~, the daughter of “‘Ra, was separated and 228Ra fraction was kept for a minimum of 30 h so as to reach equilibrium with its daughter and then counted in an argon gas flow type P-ray counter which had l-2 cpm background and 40% counting efficiency (Iyengar et al., 1990). The radiochemical method was also used to determine 2’0Pb activity. Here 210Bi, the daughter of 210Pb was separated from the sample solution and the 2’oPb fraction was kept for equilibrium with 2’oBi. Finally, it was separated as bismuth phosphate and counted in a low background /?-ray counter (Iyengar et al., 1990). The electrochemical deposition method was used for the measurement of 2roPo (Khandekar, 1977; Iyengar et al., 1990). About 20g of the dry sample were leached with HN03 + H202 and then converted into 0.5 M HCl solution. The solution was kept in a water bath at 90°C and 2’0Po was spontaneously plated by electrochemical displacement onto a silver disc. The disc was washed with distilled water, rinsed with alcohol, dried under an infrared lamp and the a-activity was counted in a ZnS(Ag) scintillation counter of 0.1 cpm background and 30% counting efficiency. Appropriate corrections for the growth of 2’oPo from “‘Pb and also for the decay of “‘PO were applied. Caesium- 137 and 9”Sr activities were measured by using the radiochemical method (Iyengar et al., 1990). Caesium-137 was separated as Cs2SnCld by using a Cs carrier and counted in a P-ray counter. To determine the activity of 90Sr, its daughter, 9oY, was separated and the “‘Sr fraction was kept for the equilibrium build up with 9oY. 9oY was finally separated as yttrium oxalate and counted in a b-ray counter. The activity of 40K was measured by employing y-ray spectrometry
34
A. P. Radhakrishna
et al.
method (Ramachandran & Mishra, 1989). The t-ray spectrometer consisted of a 10 x 10 cm NaI(T1) well-type crystal (M/S Harshaw Inc.) coupled to a 4K-channel pulse-height analyser. The detector was enclosed in a massive lead shielding of 15 cm thick lead blocks, lined with cadmium and copper sheets to reduce the intensity of lead X-rays. The spectrometer was calibrated using the standard sources of ‘37Cs, 40K, 226Ra and Th. The counting efficiency of the spectrometer in the 40K region was 15%. Ashed samples were filled in a 2 cm dia x 8 cm height plastic vial up to the top and kept inside the detector and counted for 50 000 s. The processing and counting of the environmental samples were carried out in the Environmental Survey Laborator, Kalpakkam, established by the Department of Atomic Energy, Government of India. The overall accuracy of different procedures was continually monitored in this laboratory by analysing periodically standardised matrices containing certified analytes provided by international agencies such as IAEA and the results are ascertained to be in agreement with certified values.
RESULTS AND DISCUSSIONS Radium-226 activity
In Table 1 the results are given of the activity of 226Ra and are compared with reported values for other environments. It can be seen that 226Ra activity is relatively high in soil and sand samples. Among the soil and sand samples, the activity is higher in soil samples, especially for the Ullal beach area, where the presence of monazite patches has already been reported (Radhakrishna et al., 1993). Mishra and Sadasivan (1971) analysed a large number of soil samples of different places in India by y-ray spectrometry and reported the 226Ra activity to be in the range of 2.59-26.3 Bq kg-’ with a mean value of 14.7 Bq kg-‘. The results obtained in the present work compare well with these literature values. The 226Ra activity in milk samples fall well within the range reported by Maul and O’Hara (1989). The activities in fish samles are comparable with reported values for Bombay, Kalpakkam, Italy, USA and other environments. The 226Ra activity in rice samples is comparable with reported values for other environments. The observed 226Ra activity in vegetable samples is comparable with reported values for some other areas of the world, but smaller compared to the reported values for Chavra in Kerala, Ramsar in Iran, and Black Forest in Germany. From the geometric mean values of 226Ra in soil and vegetables, the
Distribution qf’natural and artificial radionuclides in South India
35
soil-to-plant transfer coefficients (the ratio of activity concentration in plant to that in soil) were estimated. The transfer coefticients for vegetables was found to be 4 x IO-” and for rice 7 x IO-‘. The relatively higher values for rice may be due to the longer growing period of the paddy. This fact incidentally confirms the earlier findings, viz. the uptake of the radionuclides by plants depend upon soil characteristics, climatic conditions, type of plants, physical and chemical properties of radionuclides (Bettencourt et al., 1988). The transfer coefficients of ‘lhRa for vegetables reported in the literature are in the range of 0.07 x lo-‘-0.75 (Bettencourt et al., 1988). Paul and Pillai (1986) carried out an extensive investigation on uptake of 226Ra and 228Ra by rice and a variety of vegetables in Kerala and reported transfer coefficients are in the range of 4.2 x 10e3-0.36. Thus the values obtained in the present work are well within the range reported in the literatures. Lead-210 activity In Table 2 the results are given of 210Pb activity in various samples of Mangalore environment. It may be seen that both in soil and sand samples of high background area of Ullal beach 2’0Pb activity is considerably high. Fish samples show considerably higher activity of 2’0Pb. The activity in the rice sample is comparable to that of the Bombay samples. In vegetables, the activity is low compared with that of Kalpakkam and Black Forest of Germany. The activity of 2’0Pb in milk samples is higher compared to the literature values for different parts of the world. The 2’oPb in plants may come from fallout, and also from the root uptake (Jaworowski, 1967). The average soil-to-plant transfer coefficients were estimated for rice and vegetables using the average activity in soil and in the corresponding samples and were respectively found to be I .2 x lo-’ and 7 x 10-j. As in the case of “26Ra, a higher uptake was observed in rice compared to vegetables. Polonium-210
activity
Polonium-210 activity results are given in Table 3. The activities are relatively higher in soil and sand samples. The activity in samples from the monazite area of Ullal is quite high. The 2’oPo in soil is produced due to the decay of radionuclides of the uranium series present in the soil or due to the precipitation of radon decay products from the atmosphere. The ““PO content of the soil varies widely (8.14219 Bq kg-‘) depending upon the soil structure (Parfenov, 1974). Next to soil, fish samples show higher activity. The higher 2’oPo activity in fish samples was also observed in
Fish [S]
Milk /5 J
Sandd [2/
0.08-0.27 (0.12)
(3.6) 466-50.9 (48.7) BDL’-0.08 (0.03
84.2-120.5 (102.4) 2.8-4.9
Soil” [3/
Sand [4/
3.1-15.9 (il.l)h
Present work
Soil [8 /
Sample
Activity
Kalpakkam USA Italy World range
BDL-0.2 0.033 0.052-O. 12 0.007-0.2
All India Kalpakkam Bombay Ireland Black Forest Kerala Ramsar, Iran Kalpakkam
Samples
Kalpakkam Kerala Italy Italy USA World range Black Forest Bombay
values
Region
TABLE 1 Activity in Different
170-347.8 1011 0.003-0.02 0.007 0.009 0.03-O. 1 0~0041~78 0.32-0.62
2.59-26.3 9.25 3.33-18.5 I O-200 l3&48~1 7.8-1520” 740-3700“ 4.81
Literature
(Bq kg -‘j
Radium-226
Rajan et al. (1987) Fisenne and keller ( 1970) de Bortoli and Gaglione (1972) Maul and O’Hara (1989)
Iyengar et al. (1980) Lalit and Shukla (1982) Mastinu and Santaroni (1980) de Bortoli and Gaglione (1972) Morse and Welford (1971) Maul and O’Hara (1989) Schuttelkopf and Kiefer (1982) Ramachandran and Mishra (1989)
Mishra and Sadasivan (1971) Iyengar et al. (1980) Lalit and Shukla (1982) McAulay and Moran (1988) Schuttelkopf and Kiefer (1982) Kamath et al. (1964) Khademi et al. (1980) Iyengar et al. (1980)
Reference
.-
BDL-0.12 (0.04)
Vegetables [IO]
0~04-0~07
BDL BDL-0.1 0~01-0~30 0.03 0.2 0.02-0.3 BDL4.78” BDL-0.06 0.13-2.21d 0.04-6.29 0~01-0~04 0.056
Kalpakkam Kalpakkam Bombay USA World range Kalpakkam Kerala Bombay Ramsar, Iran Black Forest Italy USA World range
Iyengar et al. (1980) Rajan et al. (1987) Ramachandran and Mishra (1989) Morse and Welford (1971) Maul and O’Hara (1989) Rajan et al. (1987) Lalit and Shukla (1982) Lalit and Shukla (1982) Khademi e? al. (1980) Schuttelkopf and Kiefer (1982) de Bortoli and Gaglione (1972) Fisenne et al. (1987) Maul and O’Hara (1989)
“The numbers given in the square bracket indicate the number of samples analysed. ‘When the number of samples is 3 or more than 3 the geometric mean value is calculated and when it is less than 3, the arithmetic mean value is calculated. These values are reported in parentheses. ‘If the net sample count of the sample is less than twice the square root of the standard deviation of counter background, the activity reported as BDL (below detectable limit). “High background area in Ullal. The same nomenclature is followed in Table 2-7.
BDLO.09 (0.08)
Rice [S]
.I
w
8 5 ;5
Q. 6’ z r?. fi: 2 _. 3
& K’ -. 2
2 %
2
2
B 2
5 B z 2. 2
P
Sand (41
0.49-l .72 (1.05)
0.06-0.23 (0.09)
Fish [5/
Vegetables [IO]
Rice [5/
Milk (51
Sand” [2/
BDL@75 0.13 0,2 0.11 0.12-1.65 0.04 0.05 0.5631.82
0.03 0.01 0.13 0.03-0.48 0.14 0.033
384.8
(118) 2.9-4.4
Soild [3]
(3.8) 9x-141.3 (118.5) BDL-0.07 (0.04) BDL-0.39 (0.16)
22.2-122.1
3&45.2 (13,3) 89.7-146.4
Soil [8/
Literature values
Activity iBq kg~-‘j
Samples
Kalpakkam USA World range Bombay Kalpakkam USA UK Black Forest
UK USA Bombay Bombay Kalpakkam USA
Kalpakkam
-
Black Forest
Region
TABLE 2 Activity in Different
Present work
Sample
Lead-210
et al. (1980)
Iyengar et al. (1980) Morse and Welford (1971) Maul and O’Hara (1989) Ramachandran and Mishra (1989) Iyengar et al. (1979) Morse and Welford (1971) Maul and O’Hara (1989) Schuttelkopf and Kiefer (1982)
(1989)
and Kiefer (1982)
Maul and O’Hara (1989) Morse and Welford (1971) Ramachandran and Mishra Lalit et al. (1980) Iyengar et al. (1980) Morse and Welford (1971)
Iyengar
Schuttelkopf
Reference
8 s 2 R P r
$ F
s
b
E
Vegetables (IO]
Fish IS/
Rice (51
Milk (5 /
Sand” (41
Sand [4]
Soild (51
Soil [8/
Sample
(2.0) BDL-0.20 (0.06)
BDL-0.24 (0.16) 0.2 I-3.7
(1.7) 24.240.1 (37.1) BDL-0.019 (0.010)
(9.5) 2 1659.6 (24.7) 1.6-2.7
1.3-13.7
Present work
Activity
Samples
Bombay World range World range Kalpakkam Bombay Kalpakkam World range Bombay Kalpakkam Black Forest
Kalpakkam
Kalpakkam Black Forest World range
Region
TABLE 3 10 Activity in Different
values
0.015 0.02-0.2 0~003-0~018 0.1-0.5 0.12 0.98-24.6 6 0.016-0.4 BDL-O.2 0.33-l ,63
44.4
44.4 33.3-207.2 814-219
Literature
(Bq kg-‘)
Polonium-2
et al. (1980) Khandekar (1977) Maul and O’Hara (1989) Parfenov (1974) Rajan et al. (1987) Khandekar (1977) Iyengar et al. (1980) Maul and O’Hara (1989) Khandekar (1977) Rajan et a. (1987) Schuttelkopf and Kiefer (1982)
Iyengar
-
Iyengar et al. (1980) Schuttelkopf and Kiefer (1982) Parfenov (1974)
Reference
40
A. P. Radhakrishna et al.
other environments (Holtzman, 1969; Khandekar, 1977; Iyengar et af., 1980; Rajan et al., 1980; Horsic & Bauman, 1982). Plankton present in sea water accumulate some kinds of radionuclides very rapidly and retain them for a long time, which leads to a considerable degree of selective concentration of the radionuclides from the sea water (Parfenov, 1974). These plankton are the main food for marine species. Most of the 210PO content in the plants is the result of direct deposition of radon daughter products on the leaf of plants from the atmospheric precipitation. Apart from this the accumulation of 2’oPo by vegetables depends on their morphological aspects and on plant age as well as on external factors such as soil type, chemical fertilizers, frequency of precipitation and density of aerosols (Santos et al., 1990). Only in root vegetables is the uptake of 2’oPo from the soil exclusively. In the present work no root vegetables were analysed. Hence the soil-to-plant transfer coefficients for 210Po were not estimated. In order to tind out whether or not the parent and daughter nuclides are in equilibrium, the average activity ratios of 2’oPo : 210Pb were estimated. In normal soils of Mangalore, the result was found to be 0.71 suggesting that 210Po is partially in equilibrium with 2’0Pb. The activity ratios reported in the literature are in the range of 0.75-0.82 (Parfenov, 1974). On the other hand, in high background areas, they are not in equilibrium. Lead-210 activity is about 5 times higher than 2’oPo activity. The 210: 2’0Pb ratio depends on: (i) duration of 2’0Pb existing within a matrix; and (ii) whether polonium is selectively removed from its site of production by chemical or biological means (Eisenbud, 1987). In the high background area of Ullal beach, the continuous deposition of the monazite by sea wave actions, the turbulent wind blowing constantly from the sea and also the effective sequestering of 210Pb by the organic matter of the soil may be responsible for the observed disequilibrium between 210Po and 2’0Pb. The measured “‘PO activity in milk samples of Mangalore is comparable with the reported values for Bombay and the world range. The average activity ratio of 2’oPo : 210Pb in milk samples is 0.25, lower than the reported values 0.4-0.8 (Parfenov, 1974). In rice and vegetables, the average activity ratio is I.0 and 0.67, respectively. It was reported that as the growing period of the plant increases, the ratio is tending to unity (Parfenov, 1974). The result obtained for rice in the present work substantiates this viewpoint. In fish samples the average activity ratio was found to be I.90 and lies on the lower side of the range of 1.8-12.4 reported by Parfenov (1974). The observed wide variation is due to the various environmental factors which influence the concentrations of 210Po as well as 210Pb in the environment.
Distribution of natural and art$cial radionuclides in South India
41
Radium-228 activity In Table 4 the 228Ra results are given. It is clear that 228Ra activity is significantly high in monazite soil and sand samples. However, it is low compared to the literature values reported for samples of Kalpakkam monazite area (Iyengar et al., 1980). The activity in rice and vegetable samples of Mangalore environment is low compared to the activity in corresponding samples from Kalpakkam, Kerala and Brazil which are monazite areas. The average soil-to-plant transfer coefficient was estimated using the geometric mean value presented in Table 4. The transfer coefficients are 0.017 and 0.028 in vegetables and rice. Both in 226Ra and 22sRa the transfer coefficients from soil-to-plant area lower than unity, showing that plants are not preferential to pick-up of Ra, even though Ra is chemically similar to Ca. The transfer coefficients for 226Ra is an order of magnitude lower than that for *‘sRa, which indicate the preferential transfer and uptake of 228Ra and support the earlier observations of Paul and Pillai (1986). Using the geometric mean activity of 228Ra (Table 4) and 226Ra (Table 1) in soil and sand samples, the activity ratios of 228Ra: 226Ra were estimated. In the normal background radiation of Mangalore, the ratio is nearly unity in soil and sand samples. However, in Ullal beach soil, the ratio is 2.2 and in sand it is 3.8. It is reported that the activity ratio of 228Ra : 226 Ra in normal soil is nearly 1 (Eisenbud, 1987). In Kalpakkam monazite samples the reported ratio is 3615.3 and in Brazil it is 6 (Iyengar, 1989). Since monazite contains more 232Th and 228Ra belonging to Th series, its activity is more than 226Ra and the observed trend clearly reflects this fact. Potassium-40 activity The y-ray spectrometry results for 40K activity are given in Table 5. The number of samples analysed is one in each case and the activity is presented with the standard deviation of counting statistics. It can be seen that the 40K activity in soil samples is comparable with that of Kudankulam environment, but low compared to that of other areas of the country as well as outside the country. The activity is also low compared to the world range (UNSCEAR, 1982). In milk samples the activity is comparable to the result reported for the Kudankulam and Kerala areas, but higher compared to the reported world range. More extensive investigations are needed to understand the relatively higher activity present in milk. The activities in rice, fish and vegetable samples are either comparable with literature values reported for other environments or lower.
42
A. P. Radhakrishna et al
108 i 22.6
71.9*0.7
59.6 + 0.6
79.2 i 0.6
70.9 i 0.5
70.8 i 0.5
85.2 & 0.4
68.2 i 0.6
Milk
Rice
Fish
Vegetables Cucumber
Brinjal
Spinach
Ladies Finger
Present work
Soil
Sample
12k-632 9.6240.7 34.78-245 2&146 1036 350 103-1362 10~700 (370) 670-1000 87 46.7698.87 40 62 55.5-86.6 44.488.8 31.5-88.7 17.4-46.3 76.2-129.2 72.2-98.86 90 4g-240 79.4 9.6-37 33.9 108.8, 64.7 33.9 91.4136.9 75.9-242 X1.4218.3 104 20. 6.3, 60.7
Samples
World range Kerdla Kerala Kerala Kerala Kerabd Bombay Bombay Bombay Bombay Kerala
Kalpakkam Bombay Bombay Kudankulam Maryland, USA Ireland Kerala World range Finland Kudankulam Kerala World range World range Bombay Bombay Kerala Kerala Bombay Kerala
Region
TABLE 5 Activity in Different
Literature values
Activity (Bq kg-‘)
Potassium-40
Kannan et al. (1992) Kamath et ul. (1964) Lalit and Shukla (1982) Lakshmi (1990) Pinkerton et al. (1964) McAulay and Moran (1988) Lalit and Shukla (1982) UNSCEAR (I 982) Klemola et al. (1991) Lakshmi (1990) Mistry et al. (1970) Maul and O’Hara (1989) Maul and O’Hara (1989) Ramachandran and Mishra (1989) Lalit and Shukla (1982) Lalit and Shukla (1982) Mistry et al. (1970) Ramachandran and Mishra (1989) Mistry et al. (1970) Maul and O’Hara (1989) Maul and O’Hara (1989) Mistry et al. (1970) Lalit and Shukla (1982) Lalit and Shukla (1970) Lalit and Shukla (1982) Mistry et al. ( 1970) Lalit and Shukla (1982) Ramachandran and Mishra (1989) Lalit and Shukla (1982) Lalit and Shukla (1982) Lalit and Shukla (1982)
Reference
44
A. P. Radhakrishna et al.
Strontium-90 activity The results obtained for ?Sr activity are given in Table 6. It can be seen that 90Sr activity in all the samples of Mangalore area is, in general, low compared to the reported values for other environments. The activity of 90Sr in soil and milk samples is close to BDL. Strontium-90 activity in fish samples of Mangalore is low compared with the values reported for Kalpakkam environment. Caesium-137 activity Table 7 contains the results of 13’Cs activity. It is interesting to note that compared to 90Sr activity, ‘37Cs activity is present in appreciable amounts in samples from Mangalore. The activity in soil samples of Mangalore is lower than that of Kalpakkam and is comparable with activity for the Bombay and Hawaii areas. The ‘37Cs activity in soil samples of Mangalore is low compared to Finland, Greece and Japan. These findings indicate that fallout activity due to the Chernobyl accident has not reached the Indian environment significantly. Caesium-137 is chemically similar to potassium and is therefore ingested quantitatively when taken into the animal body through food, and excretion of 137Csthrough the milk is very rapid because its biological half-life in a cow is only 20 days (Vohra et al., 1961). Furthermore, milk is one of the common items of food of all sections of the people. Hence, the estimation of ‘37Cs in milk is important to assess the internal dose. Vohra et al. (1961) reported ‘s’Cs activity in milk samples of different patrts of India. The values obtained in the present work for milk samples of Mangalore fall in the lower range of values reported by Vohra et al. (1961). The higher values reported correspond to the activity measured in 1961, the period in which a large number of atmospheric nuclear weapon tests were conducted in various countries and the fallout of ‘37Cs was maximum. It can also be seen from Table 7 that ‘37Cs activity in rice samples of Mangalore is low compared to the activity reported for Kalpakkam environment. In vegetable samples, the activity is comparable with that of Kalpakkam and is relatively higher compared to Bombay, while the activity is low compared to Japan and Finland. In fish samples the activity in Mangalore is lower compared to Kalpakkam and Japan and it is very low compared to the activity in fish samples of Finland. Internal dose Using the results of average activities of rice, milk, fish and vegetables presented in Tables 1-7 and the data on food consumption pattern
BDL-0.15 (0.05)
BDL-0.04 (0.03)
BDL-0.23 (0.08)
BDL-0.20 (0.03)
Fish (41
Rice [S]
Vegetables [IO]
(0.4)
BDL-0.75
Present work
Milk [S /
Soil /4]
Sample
Activity
Samples
Japan Finland Kalpakkam Kalpakkam Austria Bombay Japan Finland Taiwan Japan Kalpakkam New York Kalpakkam Japan New York Kalpakkam New York
Region
TABLE 6 Activity in Different
values
0.1-13 3.6-34 BDL-6.67 0.02ZO.17 0.33 0.1 l-0.16 0~0160~28 0.12-0.13 0.31 BDL-0.053 0.08-0.26 0.0074, 0.026 < 0.02-0.6 BDL-0.08 0.022 0.040.35 0.33
Literature
(Bq kg-‘)
Strontium-90
NIRS (1990) Klemola et al. (1991) Iyengar et a/. (1979) Rajan et al. (1987) Muck et al. (1990) Hingorani et al. (1976) NIRS (1990) Klemola et al. (1991) Chien (1989) NIRS (1990) Rajan et al. (1987) Eisenbud (1987) Rajan et al. (1987) NIRS (1990) Eisenbud (1987) Rajan et al. (1987) Eisenbud (1987)
Reference
0.051-0.43 (0.093) BDL-0.32 (0.14)
BDL-0.30 (0.18)
Rice ./5 _1
Vegetable [IO]
(1963)
Rajan ef al. (1987) NIRS (1990) Eisenbud (1987) Hasanen and Miettinen Klemola et al. (1991) Shukla et al. (1987) Rajan et al. (1987) Eisenbud (1987) Klemola ef al. (1990) NIRS (I 990) Chien (1989) Kalpakkam Japan New York Finland Finland Bombay Kalpakkam New York Finland Japan Taiwan
< 0.08-2.5 0.012-0.49 7.2 23.7-218 4.6-200 0.15-0.27 0.04-0.27 0.074 0.48-0.69 BDL-0.82 3.1
BDL-0.14 (0.06)
Milk [Sj
Fish [S]
Rao et al. (1983) Iyengar et al. (1979) Shukla et al. (1987) Cox and Fankhauser (1984) NIRS (1990) Papastefanou et al. (1988) Klemola et al. (1991) NIRS (1990) Eisenbud (1987) Vohra et al. (1961) Rajan et a/. (1987) Klemola et al. (1991) Chien (1989) Ward et al. (1989) Rajan et al. (1987)
Bombay Kalpakkam Bombay Hawaii Japan Greece Finland Japan New York All India Kalpakkam Finland Taiwan Hungary Kalpakkam
< 1.18 BDL-14.43 5.2-9.5 1.5-71.4 0.6-98 291-7671 22-6700 BDL-0.65 0,67 0.1 l-9.69 0.02-0.56 8.7 0.31 6.696 <0.02-1.31
Reference
BDL-7.4 (1.66)
values
Region
Soil [ 7/
(By kg-‘)
Samples
Literature
Activity
TABLE 7 Activity in Different
Present work
Sample
Caesium-137
Distribution of natural and artjficial radionuclides in South India
47
reported in Diet Atlas of India (ICMR, 1971). the intake of radionuclides by the population of Mangalore was estimated. The results are presented in Table 8. It can be seen from the table that the average daily intake of 40K is the maximum. However, it causes no concern because as an isotope of an essential element for metabolic activity, it is homeostatically controlled in the body (Holtzman, 1980). Next to 40K, the intake of 2’oPo is relatively more. The contributions from *“Pb and 22*Ra are also considerable. It may be noted that the major share of intake of both *“Pb and 210Po comes from fish (Tables 2 and 3). Literature values reported for other environs of the country/world are also presented in Table 9 for comparison. Using the activity intake results presented in Table 9, the annual effective internal dose due to the ingestion of different radionuclides is calculated. The results are given in Table 10. The corresponding conversion factors used to evaluate the internal doses are also given in the table. The literature values reported for other environs are given in column 4 for comparison. It is clear from columns 3 and 4 that the effective dose equivalents to the population of Mangalore area due to 226Ra and ‘j7Cs are comparatively low, that due to *“Pb is almost the same, due to 40K is comparable and due to 228Ra is relatively high. The percentage contributions for the cumulative dose from the individual radionuclides are given in the last column of the table. The population of Mangalore and surrounding regions covered under the present investigation is about 700000. The total internal dose for this population is estimated by adding the effective dose equivalent from different radionuclides (column 3, Table 10). The internal dose for the population of Mangalore is estimated to be 341 ,&v year-‘.
ACKNOWLEDGEMENT The authors would like to thank Dr D. V. Gopinath, Former Director, Health, Safety and Environment Group, BARC, Bombay, for his encouragement. The authors would like to express their special thanks to Dr M. A. R. Iyengar, Head, ESL, Kalpakkam, for many helpful suggestions and the assistance received from his colleagues. The authors acknowledge the helpful assistance of Dr K. M. Balakrishna and N. Karunakara, Department of Physics, Mangalore University. The authors are grateful to the Board of Research in Nuclear Sciences, Department of Atomic Energy, Government of India for sponsoring the research project.
Dail) in take (kg)
0.36 0.1 0.10 0.05
Food item
Rice Milk Fish Vegetables Total:
0.029 0.003 0.012 0.002 0.046
226 Ra
The Estimated
0.058 0.004 0.105 0.004 0.171
“OPb 0.058 0.001 0.20 0.003 0.262
2’oPo 0.090 0.019 0.050 0.007 0.166
“‘Ra
Dai!,l intake qfuctivity
21.60 7.19 7.92 3.9 40.61
40K
(Bq day-‘)
TABLE 8 Daily Intake of Main Food Items and Activity
0.029 0.005 0.003 0.001 0.038
9”Sr
0.032 0.006 0.014 0.009 0.061
‘37cs
a 2 Pr
$j
a 3a B $
b
l"lcs
40K “Sr
22SRa
‘lop0
*“Pb
226Ra
Radionuclide
0.06
40.6 0.04
0.166
0.262
0.171
0.046
Present work
TABLE 9
0.13 0.074 0.11 0.027 0.067 0.05 1 0.065 0.374.14 0.13 0.13 0.05 0.32 0.06 0.15 2.55 5.92 0.26, 5.2 0.56 0.7488 79.4 0.04-0.32 0.096 2.0 0.040~7 1.25
Reported values
Daily intuke (Bq da-v-‘)
Daily Intake of Radionuclides
Bombay Kalpakkam Kerala Bombay USA USA UK Brazil Bombay Bombay USA Finland Bombay Erstwhile USSR Finland Kerala Kerala Kalpakkam Brazil Bombay Kalpakkam New York San Francisco Kalpakkam Chicago
Region
in Different Regions
Ramachandran and Mishra (1989) lyengar et al. (1978) Chabra (1966) Chabra (1966) UNSCEAR (1982) Holtzman (1980) UNSCEAR (1982) Penna-Franca et al. (1970, 1972) Ramachandran and Mishra (1989) Lalit and Shukla (1981) Morse and Welford (1971) Kauranen and Miettinen (1969) Khandekar (1977) Ladinskaya et al. (1973) Kauranen and Miettinen (1969) Mistry et al. (1970) Paul et al. (1982) Iyengar (1989) Penna-Franca et al. (1972) Ramachandran and Mishra (1989) Rajan et al. (1987) Eisenbud (1987) Eisenbud (1987) Rajan et al. (1987) Eisenbud (1987)
Reference
180
122
0.7
0.4
3h
0.05”
0.02”
40K
u,& Bq-’ (ICRP, 1978). ‘@v year-‘/Bq day-’ (NCRP, “UNSCEAR (1988).
13’cs
1987).
13
60 29
0.63” 0.48”
2’oPo 22sRa
260 2.1-190 I.5514
1.8760
120
122
1.96”
“‘Pb
90Sr
65-250
Literature’ values
I
Present work
background
Europe Erstwhile USSR Asia North America
of the world Normal background of the world -
Normal
Araxa-Tapira Normal background of the world
Environ
Effective dose equivalent (ptsv year-‘)
with Other Environs
TABLE 10 and Comparison
0.43”
Dose conversion factors
Mangalore
226~~
Radionuclide
The Estimated
areas
areas
areas
by the Population
0.1
0.2
36
2 %+ a &‘. B g I P; .-
b 18 8
b 2
of
36
Percentuge of contribution (present work) (%)
Radionuclides
Distribution of natural and ar@cial radionuclides in South India
51
REFERENCES Bettencourt, A. O., Teixeira, M. M. G. R., Elias, M. D. T & Faisca, M. C. (1988). Soil to plant transfer of Ra-226. J. Environ. Radioactivity, 6, 49-60. de Bortooli, M. & Gaglione, P. (1972). Ra-226 in environmental materials and foods. Health Phys., 22, 43-8. Chabra, A. S. (1966). Ra-226 in food and man in Bombay and Kerala State (India). Br. J. Radiol., 39, 141-6. Chien, C. (1989). Environmental radioactivity and dose evaluation in Taiwan after the Chernobyl accident. Health Phys., 56, 456-71. Cox, M. E. & Fankhauser, B. L. (1984). Distribution of fallout Cs-137 in Hawaii. Health Phys., 46, 65-71. Eisenbud, M. (1987). Environmental Radioactivity, 3rd edn. Academic press. California. Eisenbud, M., Petrow, H., Drew, R. T., Roser, F. X., Kegel, G. & Cullen, T. L. (1964). Naturally occurring radionuclides in foods and waters from the Brazilian areas of high radioactivity. In The Natural Radiation Environment I, ed. Adams, J. A. S. & W. M. Lowder. University Chicago Press, Chicago, pp. 837-54. EML (1983). Procedures Manual, ed. H. L. Volchok & G. de Planque, 26th edn. Environmental Measurement Laboratory, US Department of Energy, New York. Fisenne, I. M. & Keller, H. W. (1970). Ra-226 in the diet in two US cities. US Atomic Energy Commission Report, HASL-224, New York. Fisenne, I. M., Perry, P. M., Decker, K. M. & Keller, H. W. (1987). The daily intake of U-234, 235, 238 Th-228, 230, 232 and Ra-226, 228 by New York city rsidents. Health Phys., 53, 357-63. Hasanen, E. & Miettinen, J. K. (1963. Caesium-137 content of freshwater fish in Finland. Nature, 200, 1018-9. Hingorani, S. B., Lalit, B. Y., Rajan, S. & Ramachandran, T. V. (1976). Sr-90 measurements in milk and composite diet samples in India. J. Sci. Indust. Res., 35, 557-79. Holtzman, R. B. (1969). Concentrations of the naturally occurring radionuclides Ra-226, Pb-210, PO-210 in aquatic fauna. Proceedings oj’ Symposium on Radioecology, ed. D. J. Nelson & F. Evans. Michigan, pp. 53546. Holtzman, R. B. (1980). Normal dietary levels of Ra-226 and Ra-228 and Pb-210 and PO-210 for man. In Natural Radiation Environment III, Proceedings of Int. Cocference, CONF-780422, ed. T. F. Gesell & W. M. Lowder, Vol. 2, pp. 755-8 1. Horsic, E. & Bauman, A. (1982). Uranium and Ra-226 levels in autochthonic fishes of an Adriatic Estuary. Proceedings of 2nd Special Symposium on Natural Radiation Environment, ed. K. G. Vohra, U. C. Mishra, K. C. Pillai & S. Sadasivan. Wiley Eastern, New Delhi, pp. 23943. ICRP (1978). ICRP Publication 30 and Its Supplements. Pergamon Press, Oxford. ICMR (1971). Diet Atlas of India. National Institute of Nutrition, Hyderabad. Iyengar, M. A. R. (1989). Natural radiation aspects of a low monazite environment. 9th Radiochemistry and Radiation Chemistry Symposium, IGCAR, Kalpakkam, India, 47 Jan.
A. P. Radhakrishna
52
et al.
Iyengar, M. A. R., Bhat, I. S. & Kamath, P. R. (1979). Progress Report of Environmental Survey Laboratory, Kalpakkam (1974-78) BARC/I-536. lyengar, M. A. R., Rajan, M. P., Ganapathy, S. & Kamath, P. R. (1980). Sources of natural radiation exposure in a low monazite environment. In Natural Radiation Environment III, Proceedings of ht. Conference, CONF-780422, ed. T. F. Gesell & W. M. Lowder, Vol. 2, pp. 1090-106. Iyengar, M. A. R., Ganapathy, S., Kannan, V., Rajan, M. P. & Rajaram, S. (1990). Procedure
Manual,
Workshop
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