Distribution and environmental impact of radionuclides in marinesediments along the Venezuelan coast

Juan A. Alfonso • Karla Perez • Daniel Palacios •

Helga Handt • John J. LaBrecque • Abrahan Mora •

Yaneth Vasquez

Received: 2 July 2013

� Akademiai Kiado, Budapest, Hungary 2014

Abstract The activity concentrations of 137Cs, 40K, 226Ra

and 232Th in Bq/kg from 42 marine sediment samples col-

lected at nine sampling sites were determined in order to

establish a radiological baseline along the Venezuelan coast.

The radioactivity levels were determined by means of a

gamma-ray spectroscopy system using a hyper-pure ger-

manium detector in a low-background configuration. Parti-

cle size distribution and total organic matter content were

also determined. Activity concentrations of 137Cs were lower

than the detection limit of the analytical technique (0.9 Bq/kg)

in all studied sites. The results suggest that the variation of

grain-size distribution is one of the most important factors

influencing the spatial variations of 40K, 226Ra and 232Th in

sediments along the Venezuelan coasts. In all sampling sites,

average concentrations of 40K, 226Ra and 232Th were lower

than the world average values. Activity concentrations of226Ra, 232Th and 40K in coastal marine sediments along the

Venezuelan coast could be considered to be low when

compared with global average values, indicating that they

are not apparently above of the range that might be consid-

ered normal or background. These results suggest that the

studied sites do not pose any significant radiological threat to

the population. The results attained in this study should be of

considerable value as baseline data and background refer-

ence levels for Venezuelan coastlines.

Keywords Natural radioactivity � Venezuelan coast �Marine sediments � Radionuclides

Introduction

Everyone on the planet is exposed to some background

level of radiation. Natural environmental radioactivity and

the associated external exposure due to gamma radiation

depend primarily on the geological and geographical con-

ditions, and appear at different levels in the soils of each

region in the world. Human exposure to ionizing radiation

is one of the scientific subjects that attract public attention,

since radiation of natural origin is responsible for most of

the total radiation exposure of the human population [1].

The natural radioactivity in beach sands come from natural

K, U and Th series. Also, artificial radionuclides such as137Cs can be present. The determination of baseline levels

of pollutants and/or contaminants in the environment is

very important because it serves as the control point for

evaluating future environmental alterations. Therefore, it is

important to determine the baseline levels of radionuclides

in the different environmental compartments before pol-

lution or contamination events happen. The measurement

of the natural radioactivity is necessary not only due to its

radiological impacts, but also because it acts as excellent

biochemical and geochemical tracer in the environment.

J. A. Alfonso (&) � H. Handt � A. Mora � Y. Vasquez

Centro de Oceanologıa y Estudios Antarticos, Instituto

Venezolano de Investigaciones Cientıficas (IVIC),

Apartado 20632, Caracas 1020A, Venezuela

e-mail: jalfonso@ivic.gob.ve

K. Perez

Fondo Nacional de Ciencia, Tecnologıa e Innovacion

(FONACIT), Torre Ministerial, esquina El Chorro,

Av. Universidad, Caracas, Venezuela

D. Palacios

Universidad Simon Bolıvar (USB), Apartado 89000,

Caracas, Venezuela

J. J. LaBrecque

Centro de Quımica, Instituto Venezolano de Investigaciones

Cientıficas (IVIC), Apartado 20632, Caracas 1020A, Venezuela

123

J Radioanal Nucl Chem

DOI 10.1007/s10967-014-2999-z

Radioactivity monitoring in the marine environment is

normally based on the analyses of specific nuclides in

seawater, suspended particulate matter and/or sediments. In

a marine environment, radioactive materials can be attached

to particulate matter in water. Some isotopes remain dis-

solved and are termed conservative within water. Others are

scavenged out of solution onto particulate material by

biological or chemical processes, e.g., adsorption and co-

precipitation. They may be deposited in sediments on the

bottom of the sea. Uranium and thorium radionuclides have

different behaviour in the marine environment. While ura-

nium remains dissolved in water, thorium is a particularly

insoluble element in natural waters and it is usually found

associated with solid matter [2]. The sediments play a

predominant role in aquatic radioecology. Sediments are

formed when rocks and/or organic materials are broken into

small pieces by moving water. Sediment layer settles out of

the moving water. The radioactivity contents inside the

material are normally unaffected because the breaking of a

rock into pieces does not change its chemical composition.

Sediments also play a key role in the transport and accu-

mulation of contaminants within a geographic area, thus

they can be considered as the environmental host of the

waste discharged by natural or artificial processes [3]. Only

few studies have been reported on radionuclides in sedi-

ments of Venezuela, however, such studies have only

considered a limited number of radionuclides, and have

mainly been undertaken in restricted areas. This work aims

at establishing a radiological baseline along Venezuelan

coasts, via measurement of the activity concentrations of137Cs, 226Ra, 232Th and 40K in marine sediments.

Experimental

A total of 42 coastal marine sediment samples (upper

3 cm) were collected from nine sampling sites (Fig. 1),

Paraguaipoa in the state of Zulia (site 1), Casigua, Los

Pozones and Boca de Aroa in the state of Falcon (sites

2, 3 and 4), Buche and Playa Chocolate in the state of

Miranda (sites 5 and 6), Boca de Uchire in Anzoategui

(site 7), and Mata Cuare and Isla Larga in the state of

Sucre (sites 8 and 9). After collection, each sample was

dried up at room temperature and sieved through a 2 mm

mesh-sized sieve to remove stones, pebbles and other

macro-impurities. All samples were then oven dried at a

temperature of 105 �C for 24 h to remove moisture. The

homogenized samples were then packed and sealed in an

impermeable air tight 1-L PVC container to prevent the

escape of radiogenic gases radon (222Rn) and thoron

(220Rn). About 650–700 g of sample was used for

measurements. Before measurements, the containers were

kept sealed hermetically for about 4 weeks to allow

226Ra and its short-lived decay products to reach the

secular equilibrium.

The gamma spectrometric measurements were performed

with a hyper-pure germanium (HPGe) detector with an

energy resolution of less than 1.8 keV for the 1.33 MeV

gamma-ray of 60Co and with relative detection efficiency

greater than 25 %. To reduce gamma-ray background, a

cylindrical lead shielded (100 mm thick) with a fixed bottom

and movable cover shielded the detector. The lead shield

contained an inner concentric cylinder of aluminum (0.4 cm

thick) and an outer concentric cylinder of copper (0.7 cm

thick) to absorb leads X-rays. Standard gamma-ray sources241Am, 133Ba, 137Cs and 60Co (Isotope Products Laborato-

ries, Inc.) were used to calibrate the detector energy scale. All

the samples were counted for a period of 24 h.

The activity concentrations of 137Cs, 40K, 226Ra and232Th in Bq kg-1 of dried material were determined using

the comparative method with constant geometry. Most

prominent gamma energy peaks of 295.2 and 351.9 keV

(for 214Pb); 609.31 keV (for 214Bi); 238.6 keV (for 212Pb);

911.07 keV (for 228Ac); 1,462 keV (for 40K) and

661.6 keV (for 137Cs) were considered for activity con-

centration calculations. 226Ra concentration was deter-

mined from the average concentrations of 214Bi and 214Pb,

while 232Th concentration from the average concentrations

of 212Pb and 228Ac. Full energy peak efficiencies for

coastal marine sediment matrices were determined by

RGU-1, RGTh-1, RGK-1, SOIL-6 and SL-2 reference

materials (International Atomic Energy Agency IAEA,

Vienna, Austria). The reference materials and silica blank

were prepared and measured the same as the samples. The

detection limits of 137Cs, 40K, 226Ra and 232Th for this

method were determined to be 0.9, 2, 1.8 and 1.4 Bq kg-1,

respectively. The detection limits were calculated as 4.66

times the square root of the background counts for the

respective gamma-ray.

Granulometric analysis provides basic information for

the geochemical investigations of marine sediments and

was carried out by laser granulometry (Mastersizer 2000

particle size analyzer, Malvern Instruments Ltd.) to

measure particles in the 4–2,000 lm size range [4]. Total

organic matter content was determined by ignition at

550 �C [5]. Particle size distributions and total organic

matter content were determined on one representative

sample of each sampling site. Radiological indices such

as radium equivalent activity (Raeq) and absorbed dose

rate (D) were also calculated.

Results and discussion

The average activity (Bq kg-1) values of 137Cs, 40K, 226Ra

and 232Th in coastal marine sediment from the nine

J Radioanal Nucl Chem

123

sampling sites are presented in Table 1. The calculated

values for granulometric analysis and total organic matter

content are presented in Table 2.

It can be seen in Table 1, that the nine sampling sites

had coastal marine sediments with 137Cs activities lower

than the detection limit of 0.9 Bq kg-1. Our results

suggest that little if any 137Cs fallout from the atmo-

spheric nuclear weapon test was found in these marine

sediments. It should be noted that anomalous levels, as

high as 140 Bq kg-1 of 137Cs fallout were reported to

have been measured in surface soils of the tropical cloud

forests in the island of Margarita (Venezuela) [6]. But, it

does not seem that any significant amount of this 137Cs

has been transported by man or nature to estuaries or

coastal waters. The baseline levels of 137Cs reported

herein for coastal marine sediments are very similar to

the reported in coastal marine sediments of Margarita

Island [7] and Los Roques archipelago [8] with values

B1.0 Bq kg-1.

The range of measured natural radionuclide concentra-

tions differed widely as their presence in marine environ-

ment depends on their physical, chemical and geochemical

Fig. 1 A map of the

Venezuelan coast showing the

sampling sites

Table 1 Average concentration

and standard deviation values of137Cs, 40K, 226Ra and 232Th in

the studied sites

Sampling

site

Number

of samples

137Cs

(Bq/kg)

40K

(Bq/kg)

226Ra

(Bq/kg)

232Th

(Bq/kg)

1 4 \0.9 168.3 ± 30.7 5.8 ± 3.1 9.0 ± 4.3

2 4 \0.9 51.2 ± 19.1 7.2 ± 4.3 8.5 ± 5.7

3 4 \0.9 45.2 ± 12.7 4.8 ± 2.0 6.7 ± 3.1

4 5 \0.9 150.7 ± 27.6 8.6 ± 4.8 12.9 ± 7.7

5 5 \0.9 318.4 ± 42.0 23.7 ± 8.5 31.7 ± 9.6

6 5 \0.9 257.3 ± 28.9 18.4 ± 5.5 20.3 ± 4.0

7 4 \0.9 27.8 ± 11.1 3.7 ± 0.8 5.6 ± 1.0

8 5 \0.9 75.5 ± 22.0 11.0 ± 7.0 14.7 ± 7.6

9 6 \0.9 286.5 ± 38.3 19.4 ± 8.1 22.3 ± 4.4

Table 2 Sediment texture (coarse sand, fine sand, silt and clay

content) and total organic matter content in representative sediment

samples of each studied site

Site Clay

(%)

Silt

(%)

Fine sand

(%)

Coarse sand

(%)

Total organic

matter (%)

1 0 0 99.0 1.0 5.3

2 0 0 10.6 89.4 3.5

3 0 1.4 38.5 60.1 7.4

4 0 0 80.5 19.5 5.8

5 2.4 9.6 26.4 61.5 26.6

6 0 2.6 91.1 6.3 8.6

7 0 0 4.6 95.4 3.9

8 0.2 2.7 18.3 78.7 7.8

9 1.0 3.4 47.4 48.2 11.1

J Radioanal Nucl Chem

123

properties and the pertinent environment [9]. In all sam-

pling sites, mean activity concentration is of the order40K [ 232Th [ 226Ra. 232Th concentration is found to be

higher than 226Ra concentration in all the sampling sites

along the Venezuelan coast. This may be due to the low

geochemical mobility and insoluble nature in water of

thorium. The 40K activity concentration dominates over226Ra and 232Th elemental activities like what normally

happens in soil [1].

From Table 1 one can see that the highest mean

activities of 40K, 226Ra and 232Th are found in Buche

(site 5), whereas the lowest mean activities are found in

Boca de Uchire (site 7). The obtained results (Tables 1, 2)

showed that, the lowest mean values were found in

sandy sediments, while the highest mean values were

found in sandy loam sediments. This can be attributed to

the difference in grain size texture. The radionuclide

activity concentrations increase as the particle size

decrease, because of the increase in surface area per unit

of mass [10, 11]. The increase and decrease of radio-

nuclides in soil and sediment samples are also affected

by the amount and composition of the organic matter

content, adsorption kinetics and the pH of the medium

[11]. The results show that the mean activity concen-

trations of 40K, 226Ra and 232Th are higher in the site 5,

where the total organic matter content is highest. Buche

(site 5), is an estuary located to the west of the mouth of

the Tuy River, which has a plume known to move in a

northwesterly direction and receives waste water efflu-

ents from the metropolitan area of Caracas, via the

Guaire River [12]. Desorption of radium from estuarine

sediments is enhanced by the combined effects of low

pH and high salinity [11]. Characteristics of environ-

mental radioactive particles, i.e. activity and atom/activ-

ity ratios, are related to the origin, whereas properties

such as size distribution, share, crystalline structures, and

oxidation states of matrix elements depend on the spe-

cific conditions of the release mechanisms [14].

While a plot of one radionuclide activity concentration

against another (or a calculation of a correlation coefficient)

can be used to deduce some conclusions about the coexis-

tence of the radionuclides, these correlations should not be

mistaken for actual chemical interactions among the ra-

dionuclides [15]. In the present data set, 226Ra shows a very

good linear correlation with 232Th (Fig. 2). This fact sug-

gests that both thorium and uranium series nuclides are

probably associated with the same mineral fraction [15, 16]

along the Venezuelan coast. The natural radionuclides

concentrations found in this study are within the range or

are very slightly higher than those previously reported for

coastal marine sediments and soils in Venezuela [7, 8]. In

all sampling sites, average concentrations of 40K, 226Ra and

232Th in the sediments, are lower than worldwide mean

values (worldwide mean of 226Ra, 232Th and 40K is 35, 30

and 400 Bq/kg, respectively [1, 18]). Only one sample of

the site 5 has a value slightly higher than world average of232Th. A comparison of radionuclide activities in the sedi-

ment of the studied sites and in other coastal and aquatic

environments is given in Table 3. Concentrations in coastal

marine sediments along the Venezuelan coast can be

interpreted to be low on a global scale for 226Ra, 232Th and40K, indicating that they are not apparently above of the

range that might be considered normal or background.

The absorbed dose rate is the first major step for eval-

uating the health risk. With regard to biological effects, the

radiological and clinical effects are directly related to the

absorbed dose rate. The measured activity concentrations

of 226Ra, 232Th and 40K are converted into doses by

applying the conversion factors 0.462 nGy/h for 226Ra,

0.604 nGy/h for 232Th and 0.0417 nGy/h for 40K [1]. These

factors are used to calculate the absorbed dose rate D (nGy/h)

due to radiations in air at 1 m above the ground surface,

using the following equation:

D ¼ 0:462CRa þ 0:604CTh þ 0:0417CK ð1Þ

where CRa, CTh and CK are the activity concentrations (Bq/kg)

of 226Ra, 232Th and 40K in sediment samples, respectively.

Radium equivalent Raeq (Bq/kg) is a convenient index to

describe the gamma output from different mixtures of

radium, thorium and potassium in the sediments sampled

from different locations. It is a widely used hazard index

and it is defined based on the assumption that 10 Bq/kg of226Ra, 7 Bq/kg of 232Th and 130 Bq/kg of 40K produce the

same gamma dose. It is calculated using the Eq. (2) [2, 11]:

Raeq ¼ CRa þ 1:43CTh þ 0:077CK ð2Þ

where CRa, CTh and CK are the activity concentrations (Bq/kg)

of 226Ra, 232Th and 40K in sediment samples, respectively.

The D and Raeq calculated values for our sampling sites are

0

5

10

15

20

25

30

35

0 5 10 15 20 25

232 T

h (B

q/K

g)

226Ra (Bq/Kg)

r = 0.98

Fig. 2 Scatter plot of 226Ra versus 232Th in the studied sites with

linear regression line showing positive correlation

J Radioanal Nucl Chem

123

presented in Table 4. Average absorbed dose rate (D) for

all samples is lower than the world average value (57 nGy/h)

[1]. The estimated average values of Raeq are lower than

the recommended maximum value of 370 Bq/kg for the

safe use of materials in the construction of buildings [1].

Therefore, the sites studied do not pose any significant

radiological threat to the population. The results attained in

this study should be of considerable value as base line data

and background reference level for Venezuelan coastlines.

Conclusions

All of our values for 137Cs in the studied coastal sediments

were lower than our detection limit of 0.9 Bq kg-1 dry

weight. The highest mean activities of 40K, 226Ra and 232Th

are found in Buche, whereas the lowest mean activities are

found in Boca de Uchire. Our results suggest that the

variation of grain-size distribution is one of the most

important factors influencing the spatial variations of 40K,226Ra and 232Th in sediments along the Venezuelan coasts.

The high correlation found between 226Ra and 232Th sug-

gest that both thorium and uranium series nuclides are

probably associated with the same mineral fraction in the

studied sites. The natural radionuclides activity concen-

trations found in this study are within the range or are very

slightly higher than those previously reported for coastal

marine sediments and soils in Venezuela. In all sampling

sites, average concentrations of 40K, 226Ra and 232Th are

lower than world average values. Concentrations in coastal

marine sediments along the Venezuelan coast can be

interpreted to be low on a global scale for 226Ra, 232Th and40K, indicating that they are not apparently above of the

range that might be considered normal or background. Our

results suggest that the studied sites do not pose any sig-

nificant radiological threat to the population. The results

attained in this study should be of considerable value as

base line data and background reference level for Vene-

zuelan coastlines.

Acknowledgments This work was supported by the FONACIT-

Venezuela. We thank Carlos Bastidas and Juan M. Carrera for their

assistance.

References

1. United Nations Scientific Committee on the Effects of Atomic

Radiation (2000) Sources of radiation exposure. UNSCEAR,

New York

2. El-Taher A, Madkour HA (2011) Distribution and environmental

impacts of metals and natural radionuclides in marine sediments

in-front of different wadies mouth along the Egyptian Red Sea

Coast. Appl Radiat Isot 69:550–558

Table 3 Activity concentration ranges and/or means of 226Ra, 232Th and 40K (Bq/kg) in sediment samples worldwide

Country Location 226Ra (Bq/kg) 232Th (Bq/kg) 40K (Bq/kg) Reference

India Kali river 34.1–49.4 4.6–12.2 296–525 [13]

Egypt Red sea 27.4 (18–48) 38.5 (34–110) 419.4 (214–641) [2]

Albania Butrint lagoon 13–28.6 13.1–38.1 266–657 [14]

Greece Milos volcanic island 67 (29–110) 45 (19–80) 691 (153–1,593) [17]

Italy Tyrrhenian sea 28.2 ± 4.4 91.7 ± 13.4 604 ± 30 [19]

Serbia Artificial lake 7.9–12.2 18–31.3 27.1–456 [20]

Spain Palmones river estuary 60–130 10–45 250–600 [21]

Turkey Rirtima river 16–113 17–87 51–1,605 [22]

UK Irish sea 7–58 8–59 277–1,011 [23]

Yugoslavia Bega canal 71 (53–100) 49 (42–59) 520 (420–610) [24]

Antarctic King George island 11.2–16.2 10.2–25.5 402–607 [25]

USA Reedy river 21.4 45.3 609 [26]

Korea Keum river estuary 65.7 (26.7–174) 91.1 (30.9–157) 1,005 (707–1,559) [27]

Venezuela Venezuelan coast 11.4 (2.6–28.9) 14.52 (4.2–41.8) 153.43 (15–421.2) This study

Table 4 Average radiological indexes calculated in the studied sites

Site D (nGy/h) Raeq (Bq/kg)

1 15.14 31.63

2 10.6 23.3

3 8.15 17.86

4 18.04 38.65

5 43.38 93.55

6 32.1 68.67

7 6.25 13.84

8 17.11 37.83

9 34.38 73.35

J Radioanal Nucl Chem

123

3. El-Galy MM, El-Mezayn AM, Said AF, El-Mowafy AA, Mo-

hamed MS (2008) Distribution and environmental impacts of

some radionuclides in sedimentary rocks at Wadi Naseib area,

southwest Sinai, Egypt. J Environ Radioact 99:1075–1082

4. Brunskill GJ, Orpin AR, Zagorskis I, Woolfe KJ, Ellison J (2001)

Geochemistry and particle size of surface sediments of Exmouth

Gulf, Northwest Shelf, Australia. Cont Shelf Res 21:157–201

5. Heiri O, Lotter AF, Lemcke G (2001) Loss on ignition as a

method for estimating organic and carbonate content in sedi-

ments: reproducibility and comparability of results. J Paleolimnol

25:101–110

6. LaBrecque JJ (2009) The enhanced deposition of 137Cs fallout in

tropical cloud forests. In: Koskinen AN (ed) Nuclear chemistry:

new research. Nova Science Publishers, Hauppauge, pp 15–49

7. LaBrecque JJ, Cordoves PR, Cordoves MA, Perez K, Palacios D,

Alfonso JA (2010) Distribution of 137Cs, 40K, 232Th and 238U in

coastal marine sediments of Margarita Island, Venezuela. J Ra-

dioanal Nucl Chem 238:669–674

8. LaBrecque JJ, Laine J (1995) Comparacion de la Radioactividad

Ambiental en Suelos y Sedimentos del Archipielago Los Roques

con valores de la isla de Margarita y la Costa Continental Ven-

ezolana. Acta Cient Venez 46:140–141

9. Khatir SA, Ahamed-Mustafa MO, El-Khaangi FA, Nigumi YO,

Holm E (1998) Radioactivity levels in the red Sea coastal envi-

ronment of Sudan. Mar Pollut Bull 36:19–26

10. Ramasamy V, Suresh G, Meenakshisundaram V, Ponnusamy V

(2011) Horizontal and vertical characterization of radionuclides

and minerals in river sediments. Appl Radiat Isot 69:184–195

11. Ramadan AA, Diab HM (2013) Radiological characterization and

environmental impact in northwestern coast of Egypt. J Radio-

anal Nucl Chem 296:89–95

12. Alfonso JA, Handt H, Mora A, Vasquez Y, Azocar J, Marcano E

(2013) Temporal distribution of heavy metal concentrations in

oysters Crassostrea rhizophorae from the central Venezuelan

coast. Mar Pollut Bull 73:394–398

13. Narayana Y, Rajashekara KM, Siddappa K (2007) Natural

radioactivity in some major rivers of coastal Karnataka on the

southwest coast of India. J Environ Radioact 95:98–106

14. Tsabaris C, Elefheriou G, Kapsimalis V, Anagnostou C, Vlastou

R, Durmishi C, Kedhi M, Kalfas CA (2007) Radioactivity levels

of recent sediments in the Butrint Lagoon and the adjacent coast

of Albania. Appl Radiat Isot 65:445–453

15. Nielsen AH, Murray AS (2008) The effects of holocene podz-

olisation on radionuclide distributions and dose rates in sandy

coastal sediments. Geochronometria 31:53–63

16. Margineanu RM, Duliu OG, Blebea-Apostu AM, Gomoiu C, Bercea

S (2013) Environmental dose rate distribution along the Romanian

Black Sea Shore. J Radioanal Nucl Chem 298:1191–1196

17. Papaefthymiou H, Papatheodorou G, Moustakli A, Christodoulou

D, Geraga M (2007) Natural radionuclides and 137Cs distribu-

tions and their relationship with sedimentological processes in

Patras Harbour, Greece. J Environ Radioact 94:55–74

18. Kessaratikoon P, Boonkrongcheep R, Benjaku S, Youngchauy U

(2013) Specific activities and radioactive contour maps of natural

and anthropogenic radionuclides in beach sand samples (Patong,

Kamala, Kata, Karon and Nai Yang) after tsunami disaster in

Phuket province, Thailand. J Radioanal Nucl Chem 297:247–255

19. Desideri D, Meli MA, Roselli C, Testa C (2002) Geochemical

partitioning of actinides, 137Cs and 40 K in a Tyrrhenian sea

sediment sample: comparison to stable elements. J Radioanal

Nucl Chem 251:37–41

20. Drndarski ND, Lavi N (1996) Radioactivity in sediments from

the Grliska impoundment. Water Res 30:1539–1542

21. Rubio L, Linares-Rueda A, Duena C, Fernandez MC, Clavero V,

Niell FX (2003) Sediment accumulation rate and radiological

characterization of the sediment of Palmones River estuary

(southern of Spain). J Environ Radioact 65:267–280

22. Kurnaz A, Kucukomeroglu B, Keser R, Okumusoglu NT,

Korkmaz G (2007) Determination of radioactivity levels and

hazards of soil and hazards of soil and sediment samples in Fir-

tina Valley (Rize Turkey). Appl Radiat Isot 65:1281–1289

23. Jones DG, Roberts PD, Strutt MH, Higgo JJ, Davis JR (1999)

Distribution of 137 Cs and inventories of 238Pu, 239/240Pu, 241Am

and 137Cs in Irish Sea intertidal sediments. J Environ Radioact

44:159–189

24. Bikit I, Varga E, Conkic LJ, Slivka J, Mrda D, Curcic S (2005)

Radioactivity of the Bega sediment case study of a contaminated

canal. Appl Radiat Isot 63:261–266

25. Godoy JM, Schuch LA, Nordemann DJR, Reis VRG, Ramalho

M, Recio JC (1998) 137Cs, 226,228Ra, 210Pb and 40K concentra-

tions in Antarctic soil, sediment and selected moss and lichen

samples. J Environ Radioact 41:33–45

26. Powell BA, Hughes LD, Soreefan AM, Falta D, Wall M, DeVol

TA (2007) Elevated concentrations of primordial radionuclides in

sediments from the Reedy River and surrounding creeks in

Simpsonville, South Carolina. J Environ Radioact 94:121–128

27. Lee KY, Yoon YY, Cho SY, Ko KS, Kim Y (2009) Regional

characteristics of naturally occurring radionuclides in surface

sediments of Chinese deserts and Keum River area of Korea.

J Radioanal Nucl Chem 281:287–290

J Radioanal Nucl Chem

123