ORIGINAL ARTICLE

Assessment of natural radioactivity in aquifer medium bearinguranium ores in Koprubasi, Turkey

Celalettin Simsek

Received: 29 June 2007 / Accepted: 29 October 2007 / Published online: 15 November 2007

� Springer-Verlag 2007

Abstract Koprubasi, located within Manisa Province

near the Izmir, is the biggest uranium mine where uranium

ores originate from Neogene aged altered sandstone and

conglomerate layers. The main objective of this study is to

determine the radiation hazard associated with radioactiv-

ity levels of uranium ores, and the rocks and sediments

around Koprubasi. In this regard, measured activity levels

of 226Ra, 232Th and 40K were compared with world aver-

ages. The average activity levels of 226 Ra, 232Th and 40K

were measured to be 5369.75, 124.78 and 10.0 Bq/kg in

uranium ores, 24.32, 52.94 and 623.38 Bq/kg in gneiss,

46.24, 45.13 and 762.26 Bq/kg in sandstone and con-

glomerate, 73.11, 43.15 and 810.65 Bq/kg in sediments,

respectively. All samples have high 226Ra and 40K levels

according to world average level. As these sediments are

used as construction materials and in agricultural activities

within the study area, the radiation hazard are calculated by

using dose rate (D), annual effective dose rate (He), radium

equivalent activity (Raeq) and radiation hazard index (Iyr).

All the samples have Raeq levels that are lower than the

world average limit of 370 Bq/kg. On the other hand, D,

He and Iyr values are higher than world average values.

These results indicate that the uranium ores in the Kopru-

basi is the most important contributor to the natural

radiation level. The radioactivity levels of sediments and

rocks make them unsuitable for use as agricultural soil and

as construction materials. Moreover, it is determined that

shallow groundwater in sediments and deep groundwater in

conglomerate rocks and also surface water sources in the

Koprubasi have high 226Ra content. According to envi-

ronmental radioactive baseline, some environmental

protection study must be taken in Koprubasi uranium site

and the environment.

Keywords Radioactivity � Radiological hazard �Uranium bearing sediments � Aquifer medium � Koprubasi

Introduction

Rocks and sediments around the world contain different

levels of radioactivity controlled by geological structure

and rock chemistry. Major sources of radioactivity in the

environment are the elements of uranium, thorium and

potassium. Among these elements, uranium is the most

significant source of radioactivity and decay to form

radium (Singh et al. 2006). Although presence of natural

levels of these radioactive elements in rocks, sediments and

water does not create health effects, elevated levels of

radioactivity beyond permissible standards are known to be

the most important cause of cancer in humans. High levels

of radioactivity is taken into human body via air and water

intake and cause cancers in bones, stomach, intestines and

lungs (USEPA 1986; Zepecza and Szabo 1986). Further-

more, uranium is also responsible for water and sediment

pollutions and is known to emit radiation for long periods

of time when found in construction materials that are used

for dwellings (Sroor et al. 2002; Woo et al. 2002; Hayambu

et al. 1995; Xinwei and Xiaolan 2006). Thus, presence of

uranium ores in the vicinity of residential areas demon-

strates significant problems. The use of radioactivity

containing materials in construction and/or the use of

radioactivity containing sediments in agricultural produc-

tion are the major causes for humans to be exposed to

C. Simsek (&)

Department of Drilling,

Torbali Technical Vocational School of Higher Education,

Dokuz Eylul University, Izmir 35860, Turkey

e-mail: celalettin@deu.edu.tr

123

Environ Geol (2008) 55:1637–1646

DOI 10.1007/s00254-007-1113-z

natural radioactivity. In addition, groundwater bearing

aquifers that is composed of uranium containing medium

are other sources of radioactive pollution.

The Aegean region in western Turkey is known to

contain several uranium deposits originating from Neogene

aged sandstones. It has been estimated that the uranium

reserves of Turkey are about 0.37% of world’s total ura-

nium potential (TAEK 2004). The most significant reserve

is found within the boundaries of the province of Manisa

(Manisa 2004). The Koprubasi region of Manisa province

is a good example for uranium deposits found in sandstone

formations. The uranium ore in this region is approximated

to be 2,852 tons, which is mostly found in Neogene aged

sediments and has a tenor value ranging from 0.05 to

0.08% U308 (http://www.mta.gov.tr/mta/enerji/argekorrad.

html; Manisa 2004; Yılmaz 1982). An enrichment plant

was constructed, and the site has been operated by the

General Directorate of Mineral Research and Exploration

(MTA) until the 1980s. As a result of the enrichment

process, the tenor of uranium was increased to 50%. The

plant was closed in 1980 for indefinite reasons and since

then it has been inactive.

In Koprubasi uranium mine site, both uranium and the

sandstone and conglomerates that contains uranium are

highly weathered and thus, silt, sand and gravel-sized

particles are commonly observed in the study area. Such

small-sized particles are eroded via wind effect and surface

drainage and are transported to creek beds. These materials

are then taken from creek beds and are used as agricultural

soils and as construction materials. Besides, these uranium

containing sandstones and sediments form the surfacial

aquifer medium and are known to bear groundwater that is

typically used in drinking water supply within Koprubasi

area. In addition to these sandstones, gneiss is another

typically observed rock of the area and are commonly used

as a construction material in the construction industry.

Based on this strong interaction of humans with the ura-

nium containing rocks of the region, it is extremely

important to determine the natural radioactivity levels in

the region’s rocks, sediments and water resources. Thus,

this study aims to determine natural radioactivity levels in

rocks, sediments and water resources of the district of

Koprubasi and its vicinity, where the most important ura-

nium reserves of Turkey are located.

Description of the study area

The study area is situated in western Aegean region and is

located within the boundaries of the district of Manisa

(Fig. 1). With a total population of about 25,000 according

to 2000 census results, Koprubasi is the main population

center of the study area. Main economic activities of the

region comprise poorly developed farming, and cattle

breeding with main products being olive, cotton, vegeta-

bles and fishing from Demirkopru Dam. The Koprubasi

Stream is the main drainage structure of the area that runs

from south to north and connects with Demirkopru Res-

ervoir. The Demirkopru Dam is a rock-filled structure,

which is constructed to the east of Koprubasi to provide

irrigation waters for the Lower Gediz Irrigation Scheme of

the State Hydraulic Works (DSI). Geomorphologically, the

study area is characterized by a horst that spans from west

to east with an elevation range of 250–1,650 m. The study

area demonstrates typical characteristics of inland Aegean

climate with mild winters and hot summers. Based on the

past 20 years of meteorological data, the mean precipita-

tion value of the study area is 750.3 mm; the highest

precipitation amounts occurring in December (Manisa

2004).

The basement of the area is mainly composed of

Paleozoic aged gneiss with low-grade metamorphism that

is widely observed in the Aegean Region. Several north-

west directed faults formed the basement rock, and this

zone is overlaid by the Neogene aged sediments in a non-

uniform fashion (Yılmaz 1981). The Quaternary aged

alluvium consists of silt, sand and gravel that are eroded

from Neogene rocks and Paleozoic basement rock. It

covers all rocks with discordance in central part of the

study area. The study area is mostly covered by Neogene

aged sediments, which could be divided into two groups:

(1) highly weathered conglomerate and sandstone series

and (2) claystone and clayey limestone series. The uranium

deposits are mostly observed within greenish yellow

sandstone and conglomerate series and was further found

out that gneiss is the main source of uranium deposits in the

study area (Kacmaz and Nakoman 2006).

The groundwater flow mechanism of the study area

could be analyzed in two major aquifer systems. The first

aquifer is formed from Neogene aged conglomerate and

sandstone series and demonstrates confined aquifer char-

acteristics in many parts of the area. The second aquifer is

formed from the alluvial sediments and exhibits unconfined

surfacial aquifer characteristics (Fig. 2). The confined

conglomerate and sandstone aquifer is the main aquifer of

the region, within which groundwater flows from northwest

to southeast towards Demirkopru Reservoir, and is in

hydraulic interaction with the basement strata. The source

of recharge to this aquifer is the infiltrating precipitation

from the outcropping recharge zones to the northwest of

the basin as well as the leakage from precipitation through

permeable and fractured zones. Several important drinking

and irrigation water supply wells are drilled in this main

aquifer that have depths ranging from 34 to 150 m with

flow rates of 3-5 L/s. The depth of groundwater level in the

main aquifer ranges between 17 and 37 m below ground

1638 Environ Geol (2008) 55:1637–1646

123

surface. The surface aquifer, on the other hand, has limited

supply potential and is typically used by local residents for

individual water supply purposes. Wells in this aquifer

could provide yields as high as 1–3 L/s during winter

months and less than 1 L/s during summer months. These

are typically hand-dug wells with depths ranging between 4

and 6 m, and water levels ranging between 1 and 3 m.

Sampling and experimental procedure

A total of 16 rock and sediment samples were taken from

Koprubasi and environs. In alluvial formation, the soil

samples were taken from a depth of 25 cm by using an

auger. In rocky formation, rock samples were taken from

rock surface representing various locations. A total of 21

water samples are taken from the groundwater wells and

the reservoir in wet season (February 2007). Groundwater

samples were taken after at least 10 minutes of pumping

when the temperature and the specific conductance are

stabilized. Two sets of water samples are taken from wells

and stored in 50 and 500 mL polyethylene bottles after

filtering through 0.45-lm membrane filters. To determine

the physical properties of samples, pH (WTW-pH330) and

electrical conductivity (EC) (WTW-EC330) values are

measured on the field.

For radioactivity measurements of soil and rocks, both

rock and soil samples were dried for 24 h at 105�C, cru-

shed and sieved, through 2 mm meshes. Then, 100 g of the

homogeneous samples was weighed and transferred to the

polypropylene beaker of 44 mm 9 54 mm. The samples

were conserved for a period of 1 month for 226Ra and 232Th

to reach equilibrium conditions with their radionuclide

daughters. The activity concentrations of 226Ra, 232Th and40K in the soil and rock samples were measured by gamma

spectrometer in Ege University, Institute of Nuclear Sci-

ences as described by Kumru and Balcı (1994). In this

method, the two radioactive daughters of 226Ra (214Bi and208TI) are used for quantitative and qualitative analysis

when equilibrium has been established. In this study, the

1.76-MeV peak of 214Bi was used for quantitative deter-

mination of uranium, the 2.62-MeV peak of 208Tl was used

for the quantitative determination of thorium and the 1.46-

MeV peak of radioactive potassium was used for the

quantitative determination of potassium.

For radioactivity measurements on water samples, the

radium activity measurement is made by using a collector

system that included a disintegrations directly measured by

Fig. 1 Location map of the

study area within Aegean region

Environ Geol (2008) 55:1637–1646 1639

123

the alpha scintillation counter system (Eberline Model SAC-

4) (Kumru 1992). For the water samples, most of the tests

were carried out with solutions containing several Bq of226Ra. Calibration solutions, each of 100 mL volumes, were

prepared by adding distilled water and HCl to 10 mL of

standard 226Ra solutions, containing activities of 0.185,

0.370, 0.555, 0.740, 0.925 Bq. The efficiency of the collector

system for water samples was found to be 12% in Ege

University, Institute of Nuclear Sciences.

Results and discussion

Radioactivity in uranium bearing rocks and sediments

The radioactivity levels in the uranium ore, in gneiss, sand-

stone and conglomerate formations as well as in creek bed

sediments are determined in the study area. In this regard,

radioactivity tests for 226Ra, 232Th and 40K are conducted on

rock and sediment samples. The results of the analysis are

presented in Table 1 and compared with the world radioac-

tivity levels determined by UNSCEAR (2000) as given in

Table 2. As seen from the tables, the results revealed

significant levels of radioactivity in rocks and sediments of

the study area. The average radioactivity levels of the old

uranium mine site (T1) and the uranium storage area in the

enrichment plant (T6) are determined to be 5369.75, 124.78

and10.0 Bq/kg, for 226Ra, 232Th and 40K, respectively. The226Ra and 232Th activity of uranium ore was found to be high,

whereas the 40K activity was detected to be low when

compared to UNSCEAR (2000) levels.

The 226Ra, 232Th and 40K values of the gneiss formation

found in the study area were determined to be 24.32, 52.94

Fig. 2 Geological map and

sampling locations map of the

study area (Geology map

modified from Yılmaz 1982)

1640 Environ Geol (2008) 55:1637–1646

123

Table 1 The activity and radiation hazard parameters in rocks and sediments

Sample

no

X Y Z 226Ra

(Bq/kg)

232Th

(Bq/kg)

40K

(Bq/kg)

Radium

equivalent

(Raeq) (Bq/kg)

Representative

level index (Iyr)

Dose rate

(nGy h-1)

Annual

effective dose

rate (mSv y-1)

T1 618233 4290143 397 4526.41 123.14 10.0 4703.27 31.11 2165.99 2.66

T2 613427 4290371 363 208.52 51.66 636.36 331.39 2.32 154.07 0.19

T3 619357 4289855 313 93.62 47.65 606.98 208.50 1.50 97.34 0.12

T4 619760 4289773 309 25.71 32.94 1123.68 159.34 1.25 78.63 0.10

T5 621671 4289587 262 10.75 57.38 1386.49 199.56 1.57 97.44 0.12

T6 621446 4290475 273 6213.08 126.41 10.0 6394.62 42.28 2947.21 3.61

T7 619224 4293338 338 10.0 51.54 10.0 84.47 0.59 36.16 0.04

T8 619015 4293631 338 69.0 36.71 222.57 138.63 0.97 63.33 0.08

T9 618909 4292754 315 43.5 58.71 560.02 170.58 1.25 78.91 0.10

T11 622974 4291333 297 17.7 32.46 765.45 123.06 0.95 59.70 0.07

T13 624590 4288047 231 109.86 76.7 872.64 286.73 2.07 133.47 0.16

T14 622306 4294125 345 38.63 54.34 1236.75 211.57 1.62 102.24 0.13

T15 620828 4295970 440 24.22 26.86 658.31 113.32 0.87 54.86 0.07

T16 626461 4292565 311 25.02 29.66 676.42 119.52 0.91 57.68 0.07

T17 627155 4290697 225 31.08 32.58 887.61 146.02 1.12 71.05 0.09

T18 622068 4289506 215 57.26 46.43 1040.76 203.79 1.54 97.89 0.12

Table 2 Mean value of activity and radiation hazard in various rocks and sediments

Radioactive elements Ranges Uranium

ore (n = 2)

Gneiss

(n = 2)

Conglomerate

and sandstone

(n = 6)

Alluvium

sediments

(n = 6)

UNSCEAR

(range and

average value)

226Ra (Bq/kg) Min 4526.41 10.0 17.70 10.75 8

Max 6213.08 38.63 109.86 208.52 160

Mean 5369.75 24.32 46.24 73.11 40232Th (Bq/kg) Min 123.14 51.54 26.86 32.58 4

Max 126.41 54.34 76.70 57.38 130

Mean 124.78 52.94 45.13 43.15 3540K (Bq/kg) Min 10.0 10.0 560.02 606.98 100

Max 10.0 1236.75 1040.76 1386.49 700

Mean 10.0 623.38 762.26 810.65 370

Radium equivalent (Raeq) (Bq/kg) Min 4703.27 84.40 113.32 138.63 –

Max 6394.62 211.57 286.73 331.39 370

Mean 5548.94 147.98 196.77 197.63 –

Representative level index (Iyr) Min 31.11 0.59 0.87 0.97 –

Max 42.28 1.62 2.07 2.32 –

Mean 36.69 1.11 1.26 1.45 –

Dose rate (nG yr-1) Min 2165.21 36.16 54.86 71.05 –

Max 2947.99 102.21 133.47 154.07 55

Mean 2556.60 69.20 80.42 93.64 –

Annual effective dose rate (mSv yr-1) Min 2.66 0.04 0.07 0.08 –

Max 3.61 0.13 0.16 0.19 0.07

Mean 3.14 0.08 0.10 0.12 –

Environ Geol (2008) 55:1637–1646 1641

123

and 623.38 Bq/kg, respectively. Based on these results, the226Ra activity was found to be lower than the UNSCEAR

(2000) level of 40 Bq/kg, whereas the 232Th and 40K

activities were detected to be higher than the corresponding

UNSCEAR (2000) levels (Table 2). Potassium formed as a

result of the alternation of silicates in gneiss is believed to

be source of 40K activity observed in the samples.

Significant levels of radioactivity were locally detected

within the conglomerates and sandstones of the area that

overlie non-uniformly over the gneiss. In this regard, the

average levels of 226Ra, 232Th and 40K were measured to be

46.24, 45.13 and 762.26 Bq/kg, respectively, where the

highest levels of 226Ra and 232Th activities were detected at

samples T13 and T18 collected from sandstone and con-

glomerate samples (Fig. 2). The 226Ra and 232Th activities

of the sandstone and conglomerate samples taken from the

northwestern parts of the study area, where the most sig-

nificant uranium deposits are located, were measured to be

higher than the UNSCEAR (2000) level of 40 Bq/kg. On

the other hand, lower radioactivity levels were detected in

the sandstone samples collected from eastern parts of the

study area where uranium deposition is not present (T15

and T16). Thus, the radioactivity levels in sandstones and

conglomerates were found to depend on the presence of

uranium deposits and reach highest levels in the western-

northwestern parts of the study area.

Since regional rocks are extensively altered, a dense

surface drainage network is clearly observed in areas with

significant uranium presence (Fig. 2). A fairly thick sedi-

ment layer is deposited along the creek beds of the drainage

network as a result of sediment transport originating from

the altered sandstones found in the vicinity of the old

uranium site. The sand and silt-sized sediments deposited

along the creek beds are extensively used for agriculture,

and these flat areas are commonly utilized for residential

development. Furthermore, these sand and silt layers are

used as raw materials in construction sector in the region.

The sediment samples collected from the vicinity of the

uranium site revealed high levels of radioactivity. In this

regard, the average levels of 226Ra, 232Th and 40K activities

were detected to be 73.11, 43.15 and 810.65 Bq/kg,

respectively. It must be noted that the highest levels of226Ra and 40K activities in the entire study area were

measured in these sediment samples. The radioactivity

levels in the sediments demonstrate a decreasing trend, as

the distance from the uranium site is increased. The sam-

ples collected from the vicinity of the uranium mine site

(T2) have shown 208.52 Bq/kg 226Ra activity. This value is

higher than the average UNSCEAR (2000) levels given in

Table 2. Furthermore, the sediment sample collected from

the vicinity of the district of Koprubasi (T17) revealed226Ra , 232Th and 40K activities of 31.08, 32.58 and

887.61 Bq/kg, respectively (Table 1). Based on the

radioactivity levels observed in the sediment samples, it

could be concluded that wind and water erosion has played

an important role in the transport of uranium containing

sediments from the mine site towards the Demirkopru

Reservoir.

Evaluation of radiation hazard

The uranium ore in Koprubasi and the rock and sediment

samples in its vicinity contain high levels of radioactivity

that are above the world’s average. In particular, the

presence of uranium in granular form in and around the

mine site and in the enrichment plant of MTA is the source

of elevated levels of ambient radioactivity levels. These

levels are herein assessed by the most commonly applied

radiation assessment methods including (1) dose rate (D),

(2) annual effective dose rate (He); and, (3) c-ray radiation

hazard.

Dose rate (D)

This technique is used to assess the total air absorbed dose

rate (nGy h-1) 1 m above the ground due to the activity

concentrations of 226Ra, 232Th and 40K (UNSCEAR 2000;

Xinwei and Xiaolan 2006). The dose rate is calculated as:

D nGy h�1� �

¼ 0:0417CK þ 0:462CRa þ 0:604CTh ð1Þ

where CRa, CTh and Ck are the activity concentrations of226Ra, 232Th and 40K in Bq/kg, respectively. The dose rates

calculated for the uranium ore, rock and sediment samples

collected from the study area are presented in Tables 1 and

2. Accordingly, it could be seen that the dose rate values

range between 36.16 and 2947.21 nGy h-1. The highest

natural gamma radiation dose was computed for the sample

collected from the uranium ore (T1 and T6). With the

exception of T8, all rock and sediment samples collected

from the study area demonstrate radiation levels that are

higher than the world average value of 55 nGy h-1. The

average dose rates of sediments, sandstones and gneisses

are determined to be 93.64, 80.42 and 69.20 nGy h-1,

respectively; all representing values higher than the world

average value.

Annual effective dose rate (He)

This technique is computed based on the following formula

as given in UNSCEAR (2000) and Yang et al. (2005):

He mSv y�1� �

¼ D nGy h�1� �

� 8760 h y�1� �

� 0:2

� 0:7 SvG y�1� �

� 10�6 ð2Þ

1642 Environ Geol (2008) 55:1637–1646

123

The He values calculated for the uranium ore, rock and

sediment samples collected from the study area are pre-

sented in Tables 1 and 2. The annual effective dose rates in

air varied from 0.07 to 3.61 mSv y-1 with an average of

3.14 mSv y-1 in the uranium ore and a range of 0.10–

0.12 mSv y-1 in rock and sediment samples (Table 2). On

the other hand, the sediment samples collected from the

vicinity of the mine site has revealed an effective dose rate

of 0.12 mSv y-1. The annual effective dose rates in all

sediment samples are above the world average value of

0.07 mSv y-1. The major source of D and He in the study

area is the Ra versus Th originating from the mine site and

the 40K that is naturally found in regional rocks. In par-

ticular, the sediments collected from the old mine site, the

enrichment plant and the creek beds demonstrate high

levels of radiation levels that are above the world average.

The relative contributions to the absorbed dose rate and the

effective dose rate owing to 226Ra, 40K and 232Th are

calculated to be 49.9, 46.3 and 3.8%, respectively, as seen

in Fig. 3.

c-ray radiation hazard

The most commonly applied technique for calculating the

radium equivalent activity (Raeq) value is given as follows

(Beretka and Mathew 1985):

Raeq ¼ CRa þ 1:43CTh þ 0:077CK ð3Þ

where CRa, CTh and Ck are the activity concentrations of226Ra, 232Th and 40K in Bq/kg, respectively. Another index

used in computing the radiation level is the representative

level index (Iyr) that is computed as follows (NEA-OECD

1979; Alam et al. 1999):

Iyr ¼ 1=150ð ÞCRa þ 1=100ð ÞCTh þ 1=1500ð ÞCK ð4Þ

where CRa, CTh and Ck are the activity concentrations of226Ra, 232Th and 40K in Bq/kg, respectively. Iyr levels

that are less than 1 Bq/kg represent normal absorbed

radiation levels in the air. The computed Raeq and Iyr

values are given in Tables 1 and 2. As seen from the

tables, the highest Raeq and Iyr levels are observed in

samples T1 and T6 that are collected from the uranium

ore. The average Raeq and Iyr levels are calculated to be

5548.94 and 36.69 Bq/kg, respectively. Uranium Raeq

([370 Bq/kg) and Iyr ([1 Bq/kg) are significantly higher

than the world average value. The sediment samples

contaminated by the uranium ore has revealed Raeq and

Iyr levels of 331.39 and 2.32 Bq/kg, respectively, as seen

from Table 2. These average levels are calculated to be

196.77 and 1.26 Bq/kg, respectively, in sandstone and

conglomerate samples and 147.98 and 1.11 Bq/kg,

respectively, in gneiss samples. The Raeq values obtained

from all rock and sediment samples are below the world

average value of 370 Bq/kg. On the other hand, the Iyr

values of all rock and sediment samples are above

1.0 Bq/kg. The Iyr values of samples collected from the

uranium ore and the vicinity of the enrichment plant

have been calculated to be 2.32 and 42.28 times higher

than the normal levels.

Based on these results, it could be concluded that the

district of Koprubasi, the most important uranium site of

0%

20%

40%

60%

80%

100%

T1 T2 T3 T4 T5 T6 T7 T8 T9 T11 T13 T14 T15 T16 T17 T18

232Th (Bq/Kg) 226 Ra (Bq/kg) 40K (Bq/Kg)Fig. 3 Relative contributions of226Ra, 232Th and 40K activity in

samples

Environ Geol (2008) 55:1637–1646 1643

123

Turkey, and its immediate vicinity contains above normal

levels of radiation originating from the old mine site as

well as in the regional rocks and sediments. In particular,

the c-ray radiation levels of the uranium ore, sediments and

rocks situated in the immediate vicinity of the old mine site

are significantly higher than the world average values.

Radioactivity in waters

As discussed in previous sections, the rocks and sediment

layers of the study area demonstrate aquifer properties and

bear groundwater that is utilized for drinking water pur-

poses as well as for agricultural irrigation. The high levels

of radioactivity in rocks and sediments are also crucial with

regard to determining the radioactivity levels in surface and

subsurface water resources of the study area. In this regard,

water samples are collected from the surfacial alluvial

aquifer (K5, K7, K8 and K15) that comprises creek sedi-

ments, from the sandstone aquifer (K2, K3, 4, 5, 8, 9, 10,

11, 12, 13, 14, 16, 17, 18, 19, 20 and 21) and from the

reservoir (K22). The results of the radioactivity levels in

these water samples are given in Table 3. Based on these

results, the pH values of groundwater samples collected

from sediments and sandstones are weakly acidic to neutral

(6.61 to 7.85), whereas the pH value of the reservoir waters

are basic (8.05). The Eh potential of all water samples

range between -60 and +10, with lowest Eh values being

measured in basic waters and highest values being mea-

sured in groundwater samples collected from the vicinity of

the uranium mine site (K3, K9 and K7). The electrical

conductivity values in groundwater samples collected from

both the surfacial aquifer and the sandstone aquifer range

between 182.6 and 1,221 lS/cm, with highest value

occurring within the sediments located next to the mine site

(K7). When the EC distribution in samples collected from

the sandstones are considered, it is observed that the

highest values are observed in the northwestern parts of

the study area where uranium presence is at its maximum.

The water temperatures, on the other hand, range between

6.6 and 21.6�C, with samples collected from the sediment

layers being generally colder than the samples collected

from the sandstones. With respect to physical characteris-

tics, it could be concluded that groundwater samples are

influenced from the uranium containing rocks and sedi-

ments as a result of rock–water interaction.

Being a decay series element of uranium, the radioactive

radium 226Ra analysis is conducted to detect the presence

of natural radioactivity in water samples, and the results of

these analyses are presented in Table 3. It is known that the

presence of radium in different forms in natural waters is

one of the major causes of radioactivity-originated cancers.

It accumulates in bone tissue and causes bone and liver

cancers (USEPA 1991). The international standard on

combined radium (226Ra + 228Ra) is set at 5 pCi/L,

whereas the maximum allowable limit for 226Ra is set at

15 pCi/L (USEPA 1991). In this regard, the 226Ra levels

range between 5.8 and 12.8 pCi/L in water samples col-

lected from sediments and between 3.3 and 11.3 pCi/L in

samples collected from sandstone and conglomerates. The226Ra level in the reservoir water was measured to be

9.5 pCi/L. These levels are below the standard values.

In particular, the K2 sample collected from the drinking

water supply well of the district of Koprubasi that is drilled

in the alluvial and sandstone layers had a 226Ra level of

8.5 pCi/L (Fig. 2). Sidhu and Breithart (1998) have com-

puted risk factors of 5E10-5 and 1E10-4, for 226Ra levels

of 5 and 10 pCi/L, respectively. These computations are

based on an average daily human intake of radium present

in water for an average of 2 L of drinking water per day

throughout his lifetime. Based on this assessment, 5 in

100,000 people will be exposed to cancer risk for 226Ra

level of 5 pCi/L, and 10 in 100,000 people for 226Ra level

of 10 pCi/L. Although no cases of radioactivity-originated

cancers are reported within the study area, its radioactivity

levels need to be monitored on a routine basis. Further-

more, the radium levels in surface and subsurface waters of

the study area vary as a function of the pH of water. Water

Eh potential show positive correlation with pH and 226Ra,

whereas Eh show negative correlation with electrical con-

ductivity value. The dissolved uranium is shown to

increase the 226Ra levels and gross alpha activity in waters.

In this regard, water resources are influenced from rock and

sediment radioactivity which is verified particularly in high

uranium bearing rocks and sediments. Finally, the presence

of radium in reservoir waters demonstrates the fact that the

eroded sediments from the old mine site and its vicinity

could negatively influence the quality of water in the

reservoir.

Conclusions

The 226Ra, 40K and 232Th values in the uranium ore and in

the regional aquifer rocks and sediments are above

the international standards at the Koprubasi site, that is the

most significant uranium mine in Turkey. Based on the

dose rate and the effective dose rate values calculated for

the samples collected from the rocks and sediments of the

area that are used to assess the presence of radiation dan-

ger, it has been found out that inactive uranium mine and

the storage area in the abandoned enrichment plant are

significant sources of radioactive level. The average dose

rate and the average effective dose rate values were cal-

culated to be 2556.60 nG y-1 and 3.14 mSv y-1,

respectively, for the uranium ore as well as 99.71 nG y-1

1644 Environ Geol (2008) 55:1637–1646

123

and 0.12 mSv y-1, respectively, for the regional sediments

of the area. These values are above the world average

levels of 55 nGy h-1 and 0.07 mSv y-1. The Raeq values

of all samples excluding the uranium ore are below the

world average. On the other hand, the Iyr values of all

samples are above the 1 Bq/kg level, with uranium mine

having a maximum value of 42.28 Bq/kg, and sediments

having a maximum value 2.32 Bq/kg. These radioactivity

containing aquifer rocks and sediments influence the sur-

face and subsurface waters of the region and increase their

natural radioactivity levels. Therefore, the 226Ra level in

the groundwater samples collected from alluvial and

sandstone aquifers varied from 3.3 to 12.8 pCi/L. These

levels are below the standard values. In particular, the226Ra level of 9.5 pCi/L measured in the reservoir water is

a clear indication of mine site influencing the nearby water

resources as a result of wind and water erosion from the

uranium containing formations of the study area.

Due to the elevated levels of radioactivity in the rocks

and sediments of the study area, their use as construction

material in dwellings and as agricultural soils in green-

houses imply human health risks. In addition, several

precautions must be enforced to preserve the environ-

mental quality in the study area. In essence, the exposure of

uranium to air in the mine site and in the storage area

within the enrichment plant must be minimized, and ero-

sion due to wind and water from these locales must be

prevented. Sediment traps must be constructed on some of

the major creeks that drain to the Demirkopru Reservoir

such that the transport of uranium containing material to

the reservoir is prevented. Furthermore, the radioactivity

levels in groundwater utilized for drinking water purposes

must be closely monitored.

Acknowledgments This study is funded by Torbali Technical

Vocational School of Higher Education of Dokuz Eylul University.

The author expresses his gratitude to Dr. Orhan Gunduz and Osman

Erdemirtekin for their support during field studies, laboratory analysis

and manuscript preparation.

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