Enhancement of 210pO and 210 Pb in the vicinity of Syrian phosphate mines and Tartous port M. S. AI-Masri*, K. AI-Kharfan, H. Khalili, M. Abdel Haleem, Z. AIHares Department of Protection and Safety, Atomic Energy Commission of Syria, Damascus, P. 0. Box 6091 , SYRIA
Introd Detion Phosphate rocks contain relatively high concentrations of naturally occurring radioactive materials from the uranium and thorium decay series 38U and 232Th). Mining, milling and transporting of phosphate ores and manufacturing of phosphate fertilizers are ways of exposing the workers, public and the environment to enhanced natural radioactivity. These natural radionuclides are concentrated in the solid waste of phosphate fertilizers industry such as phosphogypsum, the effluent discharges and in the emission of air such as radon gas and dust carrying radioactivity. Many studies on the impact of this industry are carried out to assess the risk on human and the environment (Barisic et al., 1992; Caravalho, 1995; Hamam & Landsberger, 1994; Marovic & Sencar, 1995; Martinez & Garcia, 1996; McCartney et al., 1992; MacDonald et al., 1996; Rutherford et al., 1994; Timmrmanas et al., 1996). Some studies (UNSCEAR, 1998; Othman et al., 1992; Othman, 1993) considered radon gas is most important hazard to workers and public in the mines area and phosphate factory including phosphogypsum piles; the dose due to inhalation of radon daughters can be relatively high.
e
In Syria, the main phosphate mines are situated near Palmyra. The two open pit mine regions are separated by about 25 km; more than 2000 workers are employed in this industry and live in two villages located near the mines (Othman et al., 1993). The climate is very hot and dry where strong wind may arise. In addition, most of the mined phosphate ore is exported for more than 20 years in large quantities via one of the main Syrian ports (Tartous) situated on the east part of the Mediterranean Sea (34 54 NO, 35 52 EO). However, in both areas (mines and export platform), dust-carrying radioactivity is elevated and transported to the surroundings. Studies (Othman et al., 1994; AI-Masri et al., 2001) have reported high concentrations of 2\opO in sediment collected from Tartous shore. On the other hand, studies (Othman et al., 1992,1993) on the impact of this industry on the environment near the mines were limited to the workplace, where radon concentrations in air, and gamma exposure and hence radiation dose to workers have been determined. The main objective of this study was to assess the impact of mining activities and phosphate loading cargoes on the surrounding environment including workers villages by determination of 2\opO and 2\OPb in air particulates and soils; 2\opO and 2\OPb in the phosphate industry environment are mainly due to 222Rn decay and dust carrying phosphate ores .
• Corresponding author, Email:
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1
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Materials and Methods Sampling Sampling was carried out during loadings and operations at both sites (Tartous port and the mines).Referencesitesin both areaswere chosenfar from the operations.Air
particulates werecollectedusinghighvolumeair samplers (HVAS)with airflowof 4.2 102m' hr-'; whatmanEPM2000filters(20 cm x 25 cm) beingused.soil sampleswere also collectedfrom the samelocationsusedfor air particulatesampling; only the top 5 cm layer of surfacesoil being collectedand placed in plastic bags for transportation. Analytical Methods Total suspendedparticulates in each filter were determined by weighing the filter beforeand after sampling.The collectedsoil sampleswere oven-driedat 90 oC for 24 hr. Each air filter was cut into small piecesand digestedusing concentratednitric acid for at least 24 hr after addition of a known amount of 208Po(0.2 Bq) as a yield tracer for determinationof 210Poand 2l0Pb.For soil samplesanaiysis,d.s g of each soil sample (duplicate) was digested using a combination of mineral acids (nitric and hydrochloricacid) for at least24h. Concentrationsof 210Poand 2t0Pbwere measured using the st?l9ard technique (the sjfyer disc technique) (Harley, 1978). Alpha counting of 208Po(5.15 Mev) and 2t0Po15.30 Mevi was done using an alpha spectrometer(Oasis, Oxford) with a passive ion-implanted silicon detector (active area 300 mm', backgroundcountsper day 3.6 and the minimum depletion thickness 100 pm). The plating and countingwere the! repeatedafter 6 months of storageof the solution to measurethe ingrowth of new 2'oPofrom 2l0Pband to calculatethe 2l0Pb concentrationin the original sample.The lower limit of detectionof the method used was 0.4 Bq kg-t dry vrt. Soil sampleswere also measuredby gammaspectrometers using high resolution(1.85 kev at 1.33 Mev), high relative efficiency (26Yo and 80%) lo_wbackgroundHpGe detectorsto determinegamma emitting radionuclidessuch as "oRa by measuring its gammaemitting daughters"oPb,and 2laBi. Quality Control Quality control procedures were applied using homemade control samples and duplicateanalysis.Referencesamplessuppliedby IAEA (IAEA-368, SL-1, soil 7, RGU, RGTH) were also analyzed to ensure the accuracy of the analytical results obtainedin this study.
Resultsand Discussion 210Po 210Pb and activity concentrationin the vicinity of Knefeesand Al-Sharkia mines and worker's villages Tables I and 2 show the mean values of TSP, 2l0Poand 2l0Pbconcentrationin air particulatescollectedfrom both mines areasand workers villages.TSP concentrations (Knefeesmine) varied between 877 1tgm-3at the worker village and,24106pg m-3at the factory. While in Al-Sharkia, higher concentrationswere observedand found to be
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about 56557pg m-3at the factory and 55358 pg m-3at the storageloading cells. This is due to the fact that more milling and mining operationsbeing carried out at AlSharkia mine. However, all of the reported values here are much higher than the maximum permissible concentrations(120 pg m-3).TSP in worker viiages in both areas was found to be 877 pg m-' and 848 pg m-' for Knefees and Al-Sharkia respectively; these values are 7 times higher than the maximum permissible concentrationsand they may^.b:.e due to.the dry climate and windy weather of the 2l0Po 2l0Pb region. Moreover, uranium, and concentrationsin air particulatesof all sites were found to be relatively higher than the natural levels; the highest2l0Poand 2r0Pb concentration were 47 mnq ma and 50 mBq m-3 for Knefees, respectively. Lower levels of radionuclidesin Al-Sharkia worker village were observedand they may be due to the fact that large particlescan hardly reachthe villages.
Site No.
2 J
4
5 6
Site Description A d mi n i s t r a t i o n Buildine MaintenanceWorkshoo
Workers'Villase Control Room The Factory Mine Area
TSP' t lSD uq m-' 3 4 6 6! 2 5 2 3 925!334 8 1 7! 3 7 1 22304! 13399 24106!7458 83t'7! 4408
,ttPo
,tuPb
+1SD mBo m-3 6 . 3r 1 . 3 1.6!0.4
3 . 11 0 . 7 t . 6! 0 . 4
1 . 8r 0 . 3
l.l t 0.6
4 7! 2 5 42.9r 13.9 t 1. 6! 3 . 3
+ISD mBq m-3
5 0! 2 9 3 4 . 8! l t . 2
14.2! 9.0
Tsble I Mean valuesof TSP, 2t0Poand2l0Pbconruntrationin air at phosphatemines (Knefees) Site No.
Site Description
6
StoraseCells Dryer Unit ChemicalLaboratory Austrian FactorvNO. A MaintenanceWorkshop AdministrationBuildins
7
FactoryNO. B
8 9
ElectricalWorkshop Worker's Villase
2 J A a
5
TSPt ISD ug m-' 55358!27426 27348!.10472 215t ! 499
56557!43252 2570X t503 692!280 5223X708 4740!t952 84816I 7
,.tPo
tISD mBq m-3
5 7 . 2X 3 4 . 8 3 . 7t 0 . 8 JJ.t !
t+.t
3 . 9I 1 . 8 t . 4t 0 . 2 6.4!t.0 6.2!2.02 t.6+0.2
,tupb
tISD mBo m-3 28.8! 17.0 1 4 . 2! 9 . 9 2 . 3! 0 . 3 22.1t9.2 2 . 2! 0 . 7 l.l t 0.2
2 . 7t 0 . 2 3.1t 1.7 1 . 2 0+ 0 . 0 3
Table2 Meanvaluesof TSP, t"'Po andt"tPb concentrationin air at phosphatemines (AI-Sharkia) *: Two frlters were collected and analyzed Radioactivity content of soil samplescollected from the vicinity of the two mines areaswere found to be distance and wind direction dependant;the concentrationsof the studied radionuclides decreaseas the distance from the mines area increases (Table 3). Of course,the effect of mining processesis very clear near the mine area and air particulates are transportedby wind to the villages. Uranium ("oTh) activity contentin soil samplescollectednear the village Clinic (Knefeesvillage) was found to be 194 Bq kg-t . In additio.r,ttoPo and 2l0Pbconcentrationswere also high in those samplescollectednearthe village school; I73 Bqkg-r and 233 Bqkg-r being observed
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fo. 2l0Po and 2l0Pb respectively. These high levels may be due to high radon concentrationsin the areaand not the transportof phosphatedust from the mines by wind to the village. Similar values were also found in Al-Sharkia worker village (Table 3). Therefore, radon gas should be measuredin air and monitored in the villages in order to assessthe risk to public and workers arising from inhalationsof radonand its daughters.
,r"Th
,roRa
Site No. I
2 J
4
5
6 7 8 9 I
2 J
A
5 6 7 8 9 l0 1t
Site Description
+ISD Bo ks-l
Knefees Mine AdministrationBuildine MaintenanceWorkshoo Dryer Unit The Factorv The Mine Area Village, Main Gate Village,Hieh School V i l l a s eC l i n i c Villaee.GuestHouse Al-Sharkiu Mine LoadinsCells Dryer Unit ChemicalLaboratory AustrianFactorvNO. A MaintenanceDivision A d mi n i s t r a t i o n B ui l d i n e FactoryNO. B Electrical Workshoo lase.Police Station lage,The Mosque The Mine
820!25 413! t2 821+ 26
3 r 7t t 0 5 1 0r 1 5 820+ 30 120t5 1 9 3t 6 85i3 413tt2 510r15 382!20 422t 2 364! 2 396+ 2 408+2 460+ + t
I 28r5 87r3 28018.5
+1SD Bq ks-r 824! 100 432t 56 824+ 100 312+ lg 5 1 0+ 4 8 7 5 0! 7 0 rzr 1 tz
1 9 4X 2 3
84r8 482!63 522+50 442+53 408!52 366!46 366!46 423+55 461t60 I l3rl5.5 7 5 t l0 283t34
""Po +ISD
""Pb +1SD
Bq ks-r
Bo ks-l
1455+ 14
751t38
1997! 159 l01l +81
1479+ 73
2022 + 162
6 0 1+ 3 1 760+ 39 '1184 ! 62 1 7 3t 1 0 339! 17 148r8
1 0 3 3+ 8 2 t557+ 124 2 3 3! t 9 416t38 2 1 1! t 7
7 3 1r 5 0 7s6! 6 1 794x 63 ll98t89 553+ 41 422+ 42 692+ 36
749t39 zJJ !
tz
153+8 454+ 23
8 8 5+ 7 1
809r 65 847t68 816t70 1266! 101 388t31
3 7 4+ 3 0 704! s6 10481 84 3 3 0t 2 6 2 3 5! 2 9 679 + 54
t"'Pb, ttoRaand23tTh Tabte3 Concentrationof 210Po, in soil samples from workers villagesandmines 2t0Po and2l0Pbactivity concentrationin the vicinity of Tanousport Table 4 showsthe resultsof total suspended particulatesand mean valuesof 2lOPoand 'toPb concentrationin all filters collected from Tartous port area. The results have beencomparedwith thoseobtainedfor the referencesite (ttro.8), which is 7 km south of the affectedarea(wind direction in the port areais eastnorth). TSP concentrations were found to vary between 136 and 2269 1tgm-' at the loading platform. All other valueswere also higher than the referencesite value (110 pg m-') and higher than the maximum permissiblelevels (120 pg m-'). Moreover, it is clear that dust has spread only in an areawith 500 m radius; this may be due to the fact that large particulates may be formed becauseof the high humidity in air at the coast,thereforeit is difficult to travel far distances.However, small air particulatesmay be carriedto far distances by wind and reachTartousCity.
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2l0Poand 2toPb concentrationsin particulateswere found to be high in comparisonto the reportedvaluesof the referencesite. 2l0Poin particulat", r*g.d from 1.b mBq m' lTartous City) and 305 mBq m-l at the loading platform; the natural levels Ueing between0.47-3.7 mBq m-' (Eisenbud& Gesell, 1997).Similar relation was observed for 2l0Pbat the samelocations.The highestconcentrationof 2l0Pbwas 160 mBq m:r, which is 43 times higher than the natural levels (3.7 mBq m-3;.However, the highest concentrationswere found to be within the 500 m circle from the loading platform. It can be suggestedthat wind directionand speedin the areamayaffect this distribution; air particulate carrying radioactivity can reach other areassituated severalkm north of the port. Site No.
z J A
5 6 7
8
Site Description Loadine Platform North of Loadine Platform 400m Eastof Loadins Platform De-Loadins Station Al-Maxer Area MaintenanceWorkshop Tartous City TartousBeach Cabins(Ref Site)
TSP+ ISD (us m-3) 2263' 1779!963
t22t!973 2269!t',708 l ' 7 9! 2 7
136t57 l7l138 1l0rl5
tlupo
tISD
""Pb +ISD
(mBq m-3)
(mBo m-3)
305r39 45+0.7 10.5!2.6 l3+lI
1.7t0.01 2t0.1
1.0r0.6 1.6!0.4
I 6019
3.7+0.2 2.6+0.2 1.9r0.5 1.810.2 1.7010.03 0.8t0.1 1.6!0.2
Table3 Meanvaluesof TSP,t"'Po and2t0Pbconcentrationin air at the vicinitv of Tartous port area *: Only one measurement *: Two hlters were collectedand analyzed Table 5 shows the results of natural radioactivity concentrationsof soil samples collected from Tartous area. By examining the results,226Ra,23oTh (uranium), 2l0po 2l0Pb and in soils collected near the loading platform contain high levels, which is almost phosphateore. However, it is also clear by moving out of the port area, the concentrationswere decreasedand especiallyfor 23aThand,"uku, while 2l0po and 2l0Pb concentrationswere found to be relatively high in all other sites, even at the referencesite. 2l0Poand 210Pbconcentrationsvaried between13 and 1175 Bq kg-l and 73 and,925Bqkg-r, respectively.Thesehigh concenlrationsin soil may be Aueto trigtt radon concentrationsin the area, and hencehigh 2l0Pband 2l0po fluxes, and not the transport of phosphate dust generatedduring loading and de-loading operations. Therefore,radon gas, which is generatedfrom the phosphatepiles stored near the platform in large quantities before exporting, can be considered the main hazard in these sites. Radon gas in air should be measuredand monitored and the risk arising from inhalationshouldbe assessed.
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,roRa
Site No.
Site Description WeatherForecastCenter
2
PortCustomBuildins I
a J
AdministrationBui ldine
A a
CivilConstruction Buildins
5
Loadine Platform I Loadins Platform 2 Port CustomBuildins 2 TartousCity I Arwad Island De-Loadins Station
6 7
8 9
t0
u t2
"'"Po tlSD Bo ks-r 73t6
tISD Bq ks-r 1 9 1I 4t !3 5 3 0! 3 1
-'Th
,tupb
tISD
+ISD
Bq ks-l
Bo ks-l
2 1 +4 2 7! 6 400184
828+ l 5
75tl 121! 6 6 8 8r 9 6
2 8! 2
1 0 5t 2
7 3! 1 2
656 ! 45
ll75lt3 657 + 68
874+ 55 620+ 40
418188
297+ 20 2 0 . 7+ 1 . 4
146x 16
1 5r 3
n.6r 1.7
TanousCity 2
8.4r 0.6 580t 40 144t t0
400 m East of the Loadins Platform
4 1 5r 3 0
109r6
2 0 1! 3 1 8l +7 2 6! 0 . 3 1030 r 128 224+1 641+ 4l
73+6 3l +2 925!10
419t t00
238+5
1 4 4+ 3 0
455+ 50
300r 63
8 . 3+ 1 . 7
Table 5 Natural radioactivity concentrationin soil somplescollectedfrom the vicinity of Tartousport
Conclusion
Enhanced2l0Poand 2l0Pbactivity concentrationswere found to be in air particulates and soil samplescollectedfrom the phosphatemines and export platforms at Tartous port. The highest levels of '''Po and 'ruPb were found to be more located at the workplacein the mines areasand the export p.latform,where phosphatedust carrying radioactivity being the most important risk. '''Po is also found to be enhancedthan '''Pb, which is due to the fact that 2loPois morevolatilethan210pb.
Acknowledgment Many thanks to Prof. I. Othman (G.D. of AECS) for his encouragement and support. In addition, the authors would like to thank member staff of the low-level measurement for their time spent for measuring of the prepared samples. References M.S Al-Masri S. Mamish and Y. Budeir,A. Nashwati.2t"Pband2t"Poconcentrationsin fish consuntedin Syria J. ErrvironRadioactivity a9 Q000) 34-352. M.S Al-Masri S. Mamish and Y. Budeir. The impact of phosphateloading activities on near marine environment:the Syrian coctst.J. Environ Radioactivity,58 (2002) 95-104. D. Barisic S. Lulic and Milatic P. Radium and urqnium in phosphatefertilizers and their impact on the radioactivity of water. Water Research26(1992):607- 6ll. J.P. Bolivar T.R. Garcia and LN. Garcia.Fluxes and distribution of natural radionuclidesin the production and use of fertilizer. Sixth-InternationalSymposium on Radiation Physics. Rabat1994:2p. F.P. Caravalho. 2t0Pb qnd 2"'Po in sediments and suspended matter in Tagus estuaries Portugal, local enhancement of natural levels by wastesfrom phosphate ore processing industry,Scienceof Total Environment159(1995)201-214.
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M. Eisenbud and T. Gesell. EnvironmentalRadioactivity, Fotrth Edition, Academic press, New York, 1997. H. Hamam and S. Landsberger. Studies of radioactivity and heavy metals in phosphate fertilizer. J. Radioanal.Nucl. Chemistry 1994; 194: 331-336. J.H. Harley. Manual of standard procedures, Environmental Measurement Laboratory. Departmentof Energy.USAEC Report FIASL-300.New york, 1978. G. Marovic and J. Sencar. tt"Ra andpossiblewater contaminationdue to phosphate fertilizer production,J. Radioanal.Nucl. Chemistry200(1995)9-18. A. Maninez and LM . Garcia. Anthropogenicemissionsof 2t')po,'"'pb, t'oRa in an estuqrine environmendJ. RadioanalNucl. Chemistry207(1996)357-367. M' McCartney P.J. Kershaw D.J. Allingtu A.K. Young and D. Turner. Industrial sourceso/ naturally occuruing radionuclides in the eastern lrish Sea. Radiat Protect Dosimetry 45(t9e2)711-7t4. P' McDonald M.S. Baxter and E.M. Scott. Technological enhancement of natural radionuclidesin the marine environmenf,J. Environ. Radioactivity 32(1996) 67-90. I. Othman M. Al-Hushari and G. Raja. Radiation exposure levels in phosphate mining activities.Radiat ProtectDosimetry 45(1992)197- 201. Othman L The relation betweenuranium and the number of working years in the Syrian phosphate mines,Environmental Radioactivity1993;l8: l5l-161. I. OthmanT. Yassineand I. Bhat. Measurementsof someradionuclidesin the marine coastal environmentof Syria. Scienceof TotalEnvironment 153(1994)57-60. P.M. Rutherford M.J. Dudas and R.A. Samek.Environmental impacts of phosphog,,psum, Scienceof the Total Environment149(1994) l-38. C.W. Timmrmanasand Van der SteenJ. Environmentaland occupationalimpactsof natural radioactivityfrom some non-nuclearindustriesin the Netherlands.J. Environ. RadioactiviW 32 (1996\97-104. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Sourcesand Effects of lonizing Radiation.United Nations.New york, 1998.
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