Pre- and post-Chernobyl accident levels of 129I and 137Cs in the Southern Baltic Sea by brown seaweed Fucus vesiculosus

P e- and pos -Che nobyl acciden le els o 129 I and 137 Cs in he Sou he n Bal ic Sea by b own seaweed Fucus esiculosus J.M. Gómez-Guzmán a , b , * , 1 , E. Holm a , c , S.M. Enamo ado-Báez a , d , J.A. Ab il d , A.R. Pin o-Gómez a , J.M. López-Gu ié ez a , e , M. Ga cía-León a , b a Cen o Nacional de Acele ado es (CNA), A da. Thomas Al a Edison 7, Isla de la Ca uja, 41092 Se ille, Spain b Dp o., de Física A ómica, Molecula y Nuclea , Uni e si y o Se ille, Spain c No wegian Radia ion P o ec ion Au ho i y, Øs e ås, No way d Dp o., de Física Aplicada I, E.T.S. de Ingenie ía Ag onómica, Uni e si y o Se ille, Spain e Dp o., de Física Aplicada I, Escuela Uni e si a ia Poli écnica, Uni e si y o Se ille, Spain a icle in o A icle his o y: Recei ed 26 Ma ch 2012 Recei ed in e ised o m 12 July 2012 Accep ed 9 Augus 2012 A ailable online 30 Augus 2012 Keywo ds: AMS ICP-MS 129 I 127 I Seaweed Che nobyl acciden abs ac 129 I is a e y long-li ed adionuclide (T 1/2 ¼15.7 10 6 yea s) ha is p esen in he en i onmen bo h because o na u al and an h opogenic sou ces. In his wo k 129 I concen a ion and 129 I/ 127 I a io ha e been de e mined in seaweed Fucus esiculosus collec ed in he Sou he n Bal ic Sea du ing 1982 and 1986 (pos -Che nobyl acciden ). The esul ing da a we e e alua ed in e ms o 129 I concen a ions, 129 I/ 127 I and 129 I/ 137 Cs a ios. 129 I concen a ions we e ound o be in he o de o (0.82e5.89) 10 9 a oms g 1 in 1982 and (1.33e38.83) 10 9 a oms g 1 in 1986. The 129 I/ 127 I a ios anged om (22.7e87.8) 10 10 o seaweed collec ed in 1982 and om (26.1e305.5) 10 -10 o seaweed collec ed in 1986. Also a linea ela ionship was es ablished o 127 I concen a ions in seawa e and salini y in his a ea, enabling he es ima ion o concen a ion ac o s o 127 IinF. esiculosus. The high le els o 129 I and 129 I/ 127 I in he Ka ega and hei g adually dec easing end o he Bal ic Sea indica es ha he mos impo an con ibu ion o he 129 I in en o y in he Bal ic Sea a ea comes om Sellafield and La Hague ep ocessing plan s. Wi h espec o Che nobyl acciden , 129 I concen a ions in samples collec ed in 1986 we e no much highe han hose expec ed in less con amina ed samples om 1982. This suppo s he iew ha he con ibu ion o he Che nobyl acciden o 129 I in he Bal ic egion was no significan . Ó2012 Else ie L d. All igh s ese ed. 1. In oduc ion 129 I is a long-li ed cosmogenic adionuclide (T 1/2 ¼15.7 10 6 yea s) o which he na u al abundances ha e been al e ed in a significan way by human ac ions. In na u e, i is p oduced by cosmic ays in e ac ions wi h Xe in he a mosphe e, by spon a- neous fission o 238 U and 235 U in he li hosphe e (Eisenbud and Gesell, 1997) and, o a mino ex en , by neu on-induced eac- ions on 128 Te and 130 Te in he Ea h c us (NCRP, 1983). These p ocesses lead o ypical iso opic a ios 129 I/ 127 I be ween 10 12 (Kilius e al., 1992) and 6 10 13 (Fab yka-Ma in e al., 1985). The na u al in en o y o 129 I has been es ima ed o be w230 kg, mos o which esides in he deep oceans (Rao and Fehn,1999). 129 I has also been p oduced an h opogenically du ing he las 60 yea s du ing fission p ocesses associa ed wi h ci il and mili a y nuclea ac i i- ies and acciden s, such as he Che nobyl acciden (Ap il 26 h, 1986). An es ima ed 50e150 kg o 129 I was eleased o he a mo- sphe e du ing he main pe iod (1945e1964) o nuclea weapons es ing (Raisbeck e al., 1995;Wagne e al., 1996) and a u he w6 kg we e eleased due o he Che nobyl acciden (Gallaghe e al., 2005). Howe e , he main sou ces o an h opogenic 129 Ia e nuclea uel ep ocessing plan s (La Hague-F ance and Sellafield- England, see Fig. 1). I has been es ima ed ha , by 2004, 1371 kg o 129 I had been discha ged in o he NE I ish Sea om he Sellafield plan , wi h an addi ional 182 kg eleased di ec ly o he a mosphe e in gaseous o m (G ay e al., 1995;López-Gu ié ez e al., 2004). By he end o he same yea , 3119 kg o 129 I had been eleased om La Hague plan as liquid discha ges in o he English Channel, wi h an *Co esponding au ho . Cen o Nacional de Acele ado es (CNA), A da. Thomas Al a Edison 7, Isla de la Ca uja, 41092 Se ille, Spain. Tel.: þ34 954 46 05 53; ax: þ34 954 46 01 45. E-mail add esses: [email p o ec ed],[email p o ec ed] (J.M. Gómez- Guzmán). 1 P esen add ess: Technische Uni e si ä München, Physics Depa men E12, James-F anck-S asse 1, D-85748 Ga ching bei München, Ge many. Con en s lis s a ailable a SciVe se ScienceDi ec Jou nal o En i onmen al Radioac i i y jou nal homepage: www.else ie .com/loca e/jen ad 0265-931X/$ esee on ma e Ó2012 Else ie L d. All igh s ese ed. h p://dx.doi.o g/10.1016/j.jen ad.2012.08.007 Jou nal o En i onmen al Radioac i i y 115 (2013) 134e142 addi ional 68 kg eleased in gaseous o m (López-Gu ié ez e al., 2004;Aldahan e al., 2007). These la ge eleases o 129 I om ep ocessing acili ies, along wi h he conse a i e beha iou o iodine in seawa e (Chai and Zhu, 1994) gi e a esidence ime o iodine in he ocean o 4 10 5 yea s, make 129 I an impo an oceanog aphic ace . Seaweed is use ul as a bioindica o o moni o ing adioac i e con amina ion o he sea, due o i s p ope y o concen a ing a ious elemen s p esen in he wa e . I is well known ha i can concen a e iodine o a high le el, wi h concen a ion ac o s as high as 10 4 in some b own seaweed (Hou and Yan, 1998). I has he e o e been used as a bioindica o o adioiodine, such as 131 I and 129 I(D uehl e al., 1988;Coope e al., 1998;Hou e al., 2000a). In addi ion, he ela i ely high s abili y o iodine in seaweed and he con enience o s o ing d y seaweed p esen a unique possibili y o use a chi ed seaweed collec ed a app op ia e imes and loca- ions. This p o ides use ul eco ds o he a ia ion o he an h o- pogenic 129 I le els. I has been well es ablished ha he discha ged adioac i e e fluen s om he ep ocessing acili ies a La Hague a e fi s ans e ed no hwa ds o he coas o no h-wes e n Eu ope ia he English Channel, mixed wi h e fluen om Sellafield a he No h Sea, and hen u he ans e ed by he No wegian Coas al Cu en o he A c ic (Alfimo e al., 2004). Meanwhile, he e is an inflow o saline sea wa e om he No h Sea ha en e s he Ska- ge ak b inging an h opogenic pollu an s om he Eu opean ep ocessing acili ies. 129 I in he Bal ic Sea is mainly due o allou om he a mosphe ic emissions om nuclea acili ies and emis- sions om con amina ed seawa e as iodide (especially o ming o ganic compounds, such as CH 3 I(Aldahan e al., 2006)), and ioda e (Leh o e al., 2012). The Bal ic and Black Seas became con amina ed by he Che - nobyl acciden wi h 90 S , 134 Cs, 137 Cs and 239,240 Pu. The dose a es o he public om inges ion o 137 Cs om Che nobyl in aqua ic ood ha e been es ima ed o be low, a leas one o de o magni ude lowe han hose due o na u al 210 Po (Po inec e al., 1996). The highes dose om he Che nobyl acciden was deli - e ed o he c i ical g oup in he Bal ic Sea egion, who ecei ed a maximum dose o 0.08 mS du ing 1986 (Nielsen and Kei h- Roach, 2004). While he dis ibu ion and beha iou o caesium iso opes ha e been widely s udied, less is known abou he iodine iso opes, which had a subs an ially di e en ini ial elease his o y and also di e en physical mechanisms go e ning hei deposi ion. Thus, in he 10 days pe iod a e he acciden , he ini ial la ge elease om he Che nobyl eac o con ained mainly he mo e ola ile adionu- clides such as noble gases, iodine and some caesium. The second la ge elease was associa ed wi h he high empe a u es eached in he co e mel , and con ained mos o he pa icula e caesium (B an e al., 2002). He e we p esen a s udy o 129 I concen a ion in b own seaweed Fucus esiculosus sampled a ound he coas line o Sweden a 33 di e en s a ions in he yea s 1982 and 1986 (pos -Che nobyl acciden ). The esul ing da a we e e alua ed in e ms o 129 I concen a ions, 129 I/ 127 I and 129 I/ 137 Cs a ios. 2. Sampling and adiochemical me hod B own seaweed F. esiculosus was sampled a loca ions selec ed o p o ide a ep esen a i e geog aphical dis ibu ion on all aspec s o he Swedish coas (Fig. 2). Sampling ook place in yea s 1982 (du ing he mon h o Oc obe ) and 1986 (du ing he mon h o July), and abou 1 kg o each sample was collec ed, d ied, g ound and homogenised. All samples we e chemically p epa ed using he mic owa e- diges ion me hod desc ibed by Gómez-Guzmán e al. (2011). Typically, 0.5 g o sample and 10 mL o 60% ( / ) HNO 3 sup apu e quali y (Me ck, Da ms ad , Ge many) we e in oduced in o he essels. The ope a ional condi ions we e: 200  C o 10 min ( amp o 10 min), 200  C o 20 min and 20 min o cooling o oom empe a u e. A e diges ions, he chemical sepa a ion consis ed o an o ganic compound ex ac ion ollowed by an aqueous solu ion ex ac ion. Iodine was ex ac ed om diges ed samples h ee imes wi h 10 mL CHCl 3 and hen back-ex ac ed in o aqueous solu ion by addi ion o 20 mL 0.1 M NaHSO 3 .Then he solu ion was s i ed and he SO 3 2 and SO 4 2 ions we e p ecipi- a ed by addi ion o 10 mL o sa u a ed Ba(NO 3 ) 2 solu ion ol- lowed by cen i uga ion. Finally, iodine was p ecipi a ed as AgI by adding 10 mL 0.1 M AgNO 3 solu ion, washed wice wi h dis illed wa e and d ied a 60e80  C. The mean eco e y o he adio- chemical p ocedu e was ound o be 90%. The AgI was mixed wi h abou he same olume o Nb powde and loaded in a coppe a ge holde o he measu emen o 129 I. A e he diges ion and be o e he addi ion o 2 mg o Woodwa d iodine as ca ie ( 129 I/ 127 Iz710 14 (Robe s e al., 1997)), a 1 mL aliquo o each sample was used o 127 I measu emen . These aliquo s we e dilu ed in adequa e olume o double deionised wa e (18 M U cm) o ob ain maximum s able iodine concen a ions in he o de o 20 m gL 1 . 3. Expe imen al 3.1. Measu emen o 129 I by AMS De e mina ion o 129 I/ 127 I a ios in seaweed samples was con- duc ed a he 1 MV mul ielemen compac Accele a o Mass Spec ome y (AMS) sys em a he Cen o Nacional de Acele ado es (CNA) in Se ille (Spain). De ails o he measu emen and he sys em ha e been p e iously desc ibed (Gómez-Guzmán e al., 2012;Klein e al., 2006,2007), so only a sho desc ip ion will be gi en he e. A beam o nega i e iodine ions is ex ac ed om he AgI þNb a ge using he Cs þ high-in ensi y spu e sou ce a 35 keV. A he e minal o he andem, nega i e iodine ions a e changed o posi- i e iodine ions by he s ippe (p essu e a 6 10 3 mba o a gon, which co esponds o a mass hickness o abou 0.15 m gcm 2 ) and hey a e hen accele a ed. Following accele a ion, selec ed posi i e ions (cha ge s a e þ3) a e analyzed by mass spec ome e . The 127 I Fig. 1. Annual 129 I elease o he sea om he ep ocessing acili ies in Sellafield and La Hague (compila ion un il 2004 om López-Gu ié ez e al. (2004) and he es by Moni o ing ou En i onmen (2006) and A e a Rappo En i onnemen (2006)). J.M. Gómez-Guzmán e al. / Jou nal o En i onmen al Radioac i i y 115 (2013) 134e142 135 cu en beam is measu ed in a Fa aday cup, and 129 I 3þ ions a e coun ed in a gas ioniza ion chambe . AMS measu emen s we e pe o med ela i e o a s anda d wi h known 129 I/ 127 I iso opic a io which was made by epea ed dilu ions om NIST SRM 3230 Iodine Iso opic S anda d Le el I. The iso opic a ios ob ained di ec ly by AMS measu emen o he samples (including ca ie ) we e ypically o he o de o 129 I/ 127 Iw10 10 e10 11 . Backg ound e ec s we e e alua ed h ough equen diges ions o iodine blanks (Woodwa d Iodine, om Woodwa d Iodine Co po a ion, USA), which measu ed a 129 I/ 127 I iso opic a io o (3e4) 10 13 when 2 mg ca ie was used, meanwhile he limi o de ec ion o he CNA AMS sys em was ound o be 129 I/ 127 I¼(3.11 0.16) 10 13 (Gómez-Guzmán e al., 2012). This is ypically 2 o 3 o de s o magni ude lowe han he iso opic a ios measu ed o eal samples. 3.2. Measu emen o 127 I by ICP-MS Measu emen s o 127 I con en in seaweed samples we e pe - o med a he Induc i ely Coupled Plasma Mass Spec ome y (ICP- MS) Uni o he Se icio de In es igación Ag a ia (Uni e si y o Se ille, Spain). De ails o he measu emen and he sys em ha e been p e iously desc ibed (Gómez-Guzmán e al., 2011), so only a sho desc ip ion will be gi en he e. A Quad upola ICP-MS (The mo X7, The mo, Mad id, Spain) equipped wi h a concen ic qua z nebulize (Meinha d Associa es, Golden, USA) was used o 127 I de e mina ion. The ins umen was used a no mal esolu ion and se o de ec he signal in ensi y a m/z127. Samples we e analyzed using ecommenda ions p o ided by US-EPA 200.8 me hodology adap ed o iodine. Va ious da a quali y es s we e used du ing e e y ins umen al unning, such as eplica e, ma ix ma ching, memo y e ec s, and bo h diges ion analysis and labo- a o y eac i e blanks checking. The ins umen al de ec ion limi o 127 I calcula ed as h ee imes he s anda d de ia ion o he blank, was 0.045 m gL 1 . The me hodology used o measu e he 127 I con en in seaweed samples by his echnique was p e iously alida ed by measu ing 127 I con en in s anda d e e ence ma e ials om he Na ional Ins i u e o S anda ds and Technology (NIST), he In e na ional A omic Ene gy Agency (IAEA) and he Communi y Bu eau o Re e ence (BCR) (Gómez-Guzmán e al., 2011). 4. Resul s Concen a ions o 129 I and 127 I, 129 I/ 127 I a ios and he ac i i y o 137 Cs in seaweed samples collec ed in 1982 and 1986 a ound he Swedish coas line a e shown in Table 1. I can be seen ha he concen a ion o s able iodine ( 127 I) in he seaweed a ies signifi- can ly om 54 o 178 m gg 1 o 1982 and om 37 o 372 m gg 1 o 1986 d y weigh . This a ia ion has also been obse ed in o he species o seaweed (Hou and Yan,1998;Hou e al., 2000b). The a io 129 I/ 127 I ins ead o 129 I concen a ion in seaweed could be used as an index o he 129 I le el in he su ounding seawa e o sampling loca ion, which is based on he assump ion ha seaweed has a simila capabili y o ake up and assimila e 129 I and 127 I, as p e iously epo ed by Hou e al. (2000b). 129 I concen a ions in seaweed samples we e ound o be in he o de o (0.82e5.89) 10 9 a oms g 1 in 1982 and (1.33e 38.83) 10 9 a oms g 1 in 1986 (Table 1,Fig. 3b). The 129 I/ 127 I a ios anged om (22.7e87.8) 10 10 o seaweed collec ed in 1982 and om (26.1e305.5) 10 10 o seaweed collec ed in 1986 (Table 1,Fig. 3a). Fo bo h yea s hese 129 I/ 127 I le els a e s ill wo o h ee o de s o magni ude highe han he allou backg ound le el o w10 10 (Edmonds e al., 1998;Coope e al., 1998). F om Table 1 and Fig. 3 i can be seen ha he e is a geog aphical enhancemen o 129 I concen a ions and 129 I/ 127 I a ios in samples collec ed in he Ka ega a ea (posi ions 27e33) wi h espec o seaweed samples collec ed in he Bal ic Sea coas line (posi ions 1e26). The e ec o he ho izon al g adien s in salini y has o be Fig. 2. Sampling si es (blue do s) o Fucus esiculosus ex ac ed om Ca lson and Holm (1992). Red do s ep esen he nuclea acili ies in he d ainage a e o he Bal ic Sea. The small map in he le uppe co ne shows he loca ion o Sellafield and La Hague ep ocessing acili ies wi h espec o he sampling si es. [Fo in e p e a ion o he e e ences o colou in his figu e legend, he eade is e e ed o he web e sion o his a icle.] J.M. Gómez-Guzmán e al. / Jou nal o En i onmen al Radioac i i y 115 (2013) 134e142136 e alua ed, bu p e ious esul s indica e ha a significan amoun o discha ge om he ep ocessing acili ies had been ans e ed om he No h Sea o he inne Danish wa e s and eached he wes coas o Sweden h ough he Ka ega and Skage ak. Howe e , only a mino ac ion o his con amina ed seawa e is hen ans e ed h ough he Ka ega u he o he Bal ic Sea; mos o i e u ns o he No h Sea (Hou e al., 2000b). To compa e hese 129 I concen a ions and 129 I/ 127 I a ios on a global scale, Table 2 p esen s a compa ison o 129 I le els and 129 I/ 127 I a ios in seaweed om o he loca ions wo ldwide. Fo example, Os e c and S ibilj (2008) epo ed esul s ob ained in seaweed Fucus i soides sampled du ing he summe s o 2005 and 2006 in he coas line o he Ad ia ic Sea. 129 I concen a ions and 129 I/ 127 I a ios in hese samples anged be ween (1.5e3.4) 10 9 a oms g 1 and (8.3e21.1) 10 10 , espec i ely. Resul s epo ed by F échou and Calme (2003) and ob ained in seaweed sampled be ween 1998 and 1999 in Gou y, si ed in he icini y o La Hague nuclea ep ocessing plan , show e y high 129 I concen a ions and 129 I/ 127 I a ios. Bo h ange be ween (1.4e3.2) 10 13 a oms g 1 and (1.01e1.94) 10 5 , espec i ely, be ween ou and fi e o de s o magni ude highe o ha ound in his s udy. Hou e al. (1999a) epo ed 129 I concen a ions and 129 I/ 127 I a ios in seaweed sampled in Denma k and Iceland be ween 1988 and 1992. These alues anged be ween (0.6e115) 10 9 a oms g 1 and (4e640) 10 10 , espec i ely, and we e in he same o de o magni ude as esul s ound in his s udy. Resul s epo ed by Coope e al. (1998) showed 129 I/ 127 I a ios anged be ween (2.2e80) 10 10 in seaweed sampled in No aya Zemlya be ween 1967 and 1993. This Russian a chipelago has been influenced by he impac o he So ie nuclea es s and, indi ec ly, i s wa e s a e con amina ed by Sellafield and La Hague liquid emissions ha a i e h ough he NCC (No wegian Coas al Cu en ) (A c ic Moni o ing and Assessmen P og amme, 2003). Ac i i y concen a ions o 137 Cs a ied om 600 Bq kg 1 a he no he nmos locali y (1), o 20e25 Bq kg 1 a he sou heas coas in July 1986. Fo 1982, he mean ac i i y concen a ion o 137 Cs was 92Bqkg 1 . Thus, he 137 Cs concen a ion inc eased by 2e5 imes in mos o he seaweed samples (Table 1). 5. Discussion 5.1. 127 I The Bal ic Sea is a semi-enclosed wa e body connec ed o he No h Sea h ough he S ai o Ka ega . Salini y dis ibu ions in i s su ace laye (0e10 m) show s ong ho izon al g adien s, wi h alues close o 30 psu a he Ka ega a ea. This alue dec eases owa ds he Bo hnian Bay and he gul s o Finland and Riga, whe e alues below 3 psu a e ound (Feis el e al., 2010). Ve ical s a i- fica ion is also no iceable (Hou e al., 2001). 127 I is na u ally p esen in seawa e wi h concen a ions ha inc ease wi h he salini y, as shown in Fig. 4, wi h da a om a se o wa e samples om he Bal ic Sea a ea (Hou e al., 2001;Leh o e al., 2012). Fig. 4 shows ha iodine beha iou is conse a i e, as expec ed aking in o accoun ha his adionuclide is gene ally soluble in seawa e and poo ly adso bed on o pa icula es and sedimen . Bo h iodide (I  ) and/o ioda e (IO 3  ) anions can be p esen , bu he la e p edomina es (Pen ea h, 1985). Table 1 129 I and 127 I concen a ions (d y weigh ), 137 Cs ac i i ies and 129 I/ 127 I a ios in Fucus esiculosus sampled a ound he Swedish coas line in 1982 and 1986. Quo ed unce ain ies a e 1 s . Unce ain ies ela ed o he 129 I/ 127 I a ios come om he e o p opaga ion heo y. 137 Cs da a ex ac ed om Ca lson and Holm (1992). Sampling si e 1982 1986 129 I(10 9 a oms g 1 ) (measu ed) 127 I( m gg 1 ) (measu ed) 129 I/ 127 I(10 9 ) (calcula ed) 137 Cs (Bq kg 1 ) (measu ed) 129 I(10 9 a oms g 1 ) (measu ed) 127 I( m gg 1 ) (measu ed) 129 I/ 127 I(10 9 ) (calcula ed) 137 Cs (Bq kg 1 ) (measu ed) 1 3.49 0.16 38 5 19.6 3 600 29 2 1.77 0.09 61.6 1.6 6.0 0.3 110 6 3 3.87 0.22 40 4 20.2 2.4 138 7 4 1.80 0.11 35.9 0.2 10.6 0.7 91 5 5 1.33 0.06 54 4 5.2 0.5 41 2 6 1.55 0.21 51 3 6.4 0.9 46 3 7 1.03 0.06 75 6 2.9 0.3 8.2 0.5 1.81 0.15 51.4 0.6 7.4 0.6 26 1 8 0.82 0.05 77 3 2.27 0.16 7.3 0.7 1.59 0.07 74 6 4.5 0.4 30 2 9 1.18 0.06 85 5 2.92 0.23 9.3 0.5 1.88 0.18 53 4 7.4 0.9 46 3 10 0.93 0.05 61 7 3.2 0.4 7.5 0.4 1.72 0.10 41.9 2.0 8.6 0.7 26 1 11 0.96 0.05 67 5 3.0 0.3 7.0 0.4 12 1.12 0.09 90 4 2.66 0.24 7.5 0.7 1.60 0.08 129 5 2.60 0.17 20 1 13 1.44 0.10 102 4 2.97 0.24 7.2 0.5 1.50 0.09 78.4 4.1 0.3 28 2 14 1.9 0.3 104 3 3.8 0.7 28 2 15 2.55 0.13 84 3 6.4 0.4 57 3 16 2.11 0.12 132 12 3.4 0.4 7.5 0.4 1.82 0.11 71 4 5.4 0.4 24 1 17 2.09 0.10 84 3 5.3 0.3 8.3 0.7 1.97 0.19 35 3 12.0 1.5 27 2 18 1.9 0.3 106 8 3.8 0.7 42 2 19 2.19 0.11 115 10 4.0 0.4 29 2 20 2.48 0.13 144 6 3.65 0.24 8.6 0.7 2.81 0.16 163 3 3.64 0.22 89 5 21 3.39 0.15 131 2 5.5 0.3 9.3 0.5 22 2.51 0.11 134 9 3.9 0.3 8.7 0.9 2.89 0.21 142 5 4.3 0.4 23 1 23 2.81 0.16 68 7 8.8 1.0 14.6 0.8 2.1 0.4 67 6 6.8 1.3 24 1 24 2.18 0.09 72 4 6.4 0.4 8.0 0.7 1.88 0.13 50 3 7.9 0.7 352 19 25 2.05 0.10 54 8 7.9 1.3 8.2 0.9 2.66 0.12 55 4 10.2 0.9 19 1 26 3.22 0.23 118 8 5.7 0.6 6.9 0.4 3.36 0.17 68.4 1.9 10.4 0.6 107 5 27 4.02 0.21 109 8 7.8 0.7 10.4 0.6 6.9 0.3 114 5 12.7 0.8 40 2 28 5.89 0.15 178 15 6.9 0.6 13.0 1.3 18.0 0.8 132 5 28.6 1.6 36 2 29 29.6 1.2 341 24 18.3 1.5 34 2 30 28.8 1.2 331 12 18.4 1.0 34 2 31 31.0 1.6 372 18 17.6 1.3 33 2 32 29.4 2.0 279 7 22.2 1.6 27 1 33 38.8 2.1 269 15 30.5 2.4 41 2 J.M. Gómez-Guzmán e al. / Jou nal o En i onmen al Radioac i i y 115 (2013) 134e142 137 Measu ed alues o 127 I concen a ions in F. esiculosus sampled a ound he sou he n Swedish coas line in 1982 and 1986 along wi h salini y a e shown in Fig. 5 (mean annual alues o he pe iod 1900e2005 and o 1  1  10 m size cells, aken om Feis el e al., 2010). The dis ibu ion o 127 I concen a ions, C, as a unc- ion o he sampling poin we e simila in bo h campaigns, wi h an inc easing end owa ds he S ai o Ka ega ha can be linea ly co ela ed wi h salini y, S, a 99% confidence le el (R 2 ¼0.84, p<0.01; C¼20.4$Se60.4, in uni s o m gg 1 ). 127 I concen a ions in seawa e can be in e ed om he salini y da a (Fig. 5) and om Fig. 4, which allows he es ima ion o concen a ion ac o s (defined as he a io be ween concen a ions in F. esiculosus and in seawa e ). The so ob ained alues o he wo sampling campaigns a e compa ible wi h a no mal dis ibu ion o mean alue 6540 and a s anda d de ia ion o 400. When excluding he sampling poin s om he Ka ega a ea ( hose wi h highe salini y, and index >27), he concen a ion ac o s ollow a no mal dis ibu ion wi h mean alue 5900 and s anda d de ia ion o 355. 5.2. 129 I, 137 Cs and 129 I/ 137 Cs a io The possible o igins o man-made adionuclides in he Bal ic Sea can be classified as ollows: na u al occu ence, allou om a mosphe ic nuclea weapon es s, he elease om he Che nobyl nuclea powe plan acciden , au ho ised discha ges o adioac- i i y in o he sea occu ing du ing ou ine ope a ion o nuclea ins alla ions in he Bal ic Sea egion and discha ges om Eu opean nuclea uel ep ocessing plan s. The na u al in en o y o 129 I has been es ima ed o be w230 kg, mos o which esides in he deep oceans (Rao and Fehn, 1999). I is well es ablished ha he a io 129 I/ 127 I in he p e-nuclea e a had ypical alues be ween 10 12 (Kilius e al., 1992) and 6 10 13 (Fab yka-Ma in e al., 1985). These le els, compa ed wi h he ones measu ed in F. esiculosus in his wo k, accoun o <0.05% o he o al 129 I in en o y in his egion. An es ima ed amoun o 50e150 kg o 129 I we e eleased o he a mosphe e du ing he main pe iod (1945e1964) o nuclea weapons es ing (Raisbeck e al., 1995;Wagne e al., 1996), which enhanced he na u al 129 I/ 127 I a io o 10 10 . This le el, compa ed wi h he iso opic a ios measu ed in his wo k, s ill accoun o <5% o he o al 129 I in en o y in he Bal ic Sea egion. Acco ding o Salo e al. (1986), he in en o y o 137 Cs in he Bal ic Sea due o his sou ce, based on measu ed concen a ions in wa e and sedimen s, is 620 TBq (calcula ed o 1981). Fig. 3. (a) 129 I/ 127 I a ios and (b) 129 I concen a ion (d y weigh ) in seaweed Fucus esiculosus sampled a ound he Swedish coas line in 1982 and 1986. Table 2 129 I concen a ions and 129 I/ 127 I epo ed in a ious seaweeds sampled wo ldwide. Seaweed Sampling zone 129 I(10 9 a oms g 1 ) 129 I/ 127 I (10 10 ) Re e ence Da e Loca ion F. Vi . Sep . 2005 Slo enia 2.0 0.6 424.5 34.0 (Os e c and S ibilj, 2008)F. Vi . June 2006 I aly 1.5 1.1 405.3 28.9 F. Vi . Oc . 2006 C oa ia 3.4 1.1 330.7 26.8 F. Ves. Oc . 1998 Gou y, F ance 14,000 900 99,434 985 (F échou and Calme , 2003)F. Ves. Ma ch 1999 Gou y, F ance 32,000 2300 190,992 17781 F. Ves. July 1967 K uglaya Le aya 21.4 1.1 (Coope e al., 1998) F. Ves. July 1972 Sosno e z 71.8 2.0 F. Ves. Augus 1993 G ibo aya Fjo d 789 18 F. Ves. Dec. 1988 Iceland 0.6 0.04 3.90 0.24 (Hou e al., 1999a) F. Ves. No . 1989 Klin , Denma k 62.1 4.6 393 6 F. Ves. Ap il 1992 Klin , Denma k 115.3 10.4 638 11 1982 8 0.82 0.05 22.7 0.16 This wo k F. Ves. 1982 28 5.89 0.15 88 10 a F. Ves. 1986 5 1.33 0.06 26.1 1.7 a F. Ves. 1986 33 38.8 2.1 305 24 a Highes 129 I/ 127 I a io in 1982 and lowes 129 I/ 127 I a io in 1986 we e ound in posi ions 23 and 12, espec i ely. Fig. 4. Co ela ion be ween 127 I concen a ion and salini y in seawa e . 127 I and salini y da a ex ac ed om Hou e al. (2001) and Leh o e al. (2012). J.M. Gómez-Guzmán e al. / Jou nal o En i onmen al Radioac i i y 115 (2013) 134e142138 The Che nobyl acciden , which happened in Ap il 1986, eleased a la ge amoun o adioac i e ma e ial, including abou 6 kg o 129 I (Gallaghe e al., 2005). The o al inpu o 137 Cs om he Che nobyl acciden in o he Bal ic Sea a ea was es ima ed a 4500 TBq by CEC (1991). This es ima e was la e adjus ed o 4700 TBq by Nielsen e al. (1999). The deposi ion allou om Che nobyl was e y une enly dis ibu ed in he d ainage a ea o he Bal ic Sea; he mos con amina ed a eas we e su ounding he Bo hnian Sea and he eas e n Gul o Finland. This beha iou is shown in Table 1, whe e i can be seen ha he highes 137 Cs ac i i ies in samples om 1986 a e in he no h-eas e n a ea o he Bal ic Sea. Concen a ion ac o s o 127 I can be used o econs uc he 129 I concen a ion in seawa e om he measu ed concen a ions in F. esiculosus collec ed in 1982. In he second sampling campaign, samples we e collec ed in July 1986, h ee mon hs a e he Che - nobyl acciden . The biological hal -li e o iodine in F. esiculosus has been measu ed and ound o be qui e sho , be ween 5 and 10 days (Vi es i Ba lle e al., 2007;D uehl e al., 1988). Using a CF o 14.7 m 3 kg 1 and a ypical mass o 0.261 kg (Vi es i Ba lle e al., 2008), a simple wo-compa men al model shows ha equilib- ium wi h a wa e body o w10 10 m 3 should be a ained in wo mon hs. Al hough in he eal wo ld a s eady-s a e is a ely encoun e ed, unde ou pa icula condi ions, i seems easonable o use concen a ion ac o s de i ed om 127 I o es ima ing he 129 I concen a ions in seawa e in July 1986. Fu he mo e, om he esul s shown in Table 1, 137 Cs concen a ions in F. esiculosus sha ply inc eased in samples collec ed in July 1986 (i is wo h no ing ha adionuclide discha ges om Sellafield and Cap de la Hague con inued hei dec easing end in he pe iod be ween sampling campaigns, and hus, ac i i y concen a ions lowe han hose measu ed in 1982 could be expec ed jus p io he Che nobyl acciden ). On he o he hand, he applica ion o models wi h concen a ion ac o s cons an in ime (al hough a ying om si e o si e) o 137 Cs, could easonably ep oduce he obse ed ime se ies o 137 Cs concen a ions in F. esiculosus in he Bal ic Sea, p io o and a e he Che nobyl acciden (HELCOM, 2009). Resul s a e depic ed in Fig. 6 (double panel, wi h he de ail o he common a ea co e ed by he wo sampling campaigns). Concen a ions in 1982 show an inc easing end owa ds he Ka ega S ai , consis en wi h he expec ed pa e n o 129 I dispe sion ollowing liquid discha ges om Sellafield and Cap de la Hague (Po inec e al., 2003)ewe no e ha he e ec o salini y was al eady inco po a ed in he es ima ion o concen a ion ac o s e. Wi hin his common a ea, 129 I concen a ions in 1986 a e sligh ly inc eased in some loca ions, as i could be expec ed o non-uni o m a mosphe ic deposi ion om he Che nobyl adioac i e cloud (HELCOM, 2009), and he limi ed homogeniza ion o concen a- ions p omo ed by wa e ci cula ion du ing his elapsed ime (Toscano and Ga cía-Teno io, 2004). A he wo edges o he expanded a ea o sampling in 1986, ela i ely highe concen a- ions o 129 I we e ound. To dis inguish wha ex en hey a e due o localized deposi ion om he Che nobyl acciden o i hey a e he esul o he dispe sion pa e n om he wo ep ocessing plan s, i is necessa y o s udy he 137 Cs dis ibu ion and he 129 I/ 137 Cs iso opic a ios. F om Table 1, 137 Cs concen a ions in F. esiculosus in 1982 we e a he uni o m, wi h a mean alue and s anda d de ia ion o 8.7 and 0.5 Bq kg 1 , espec i ely. I is well es ablished ha he Che - nobyl acciden was he main sou ce o 137 Cs o he Bal ic Sea. Fo example, Ca lson and Holm (1992) measu ed ac i i y a ios 134 Cs/ 137 Cs o (0.45 0.05) in seaweed sampled in hese loca ions, in good ag eemen wi h he a io (0.47e0.48) in July 1986, calcu- la ed by IAEA (1986). Thus, 137 Cs concen a ions in Fucus collec ed in 1986 we e e y high in samples 1e4 and ha can be linked wi h high local deposi ion om Che nobyl, and is also consis en wi h he high concen a ions o 129 I ound in his a ea. Isola ed peaks in 137 Cs concen a ion also appea in samples 24 and 26. By excluding hese six samples, he mean concen a ion and s anda d de ia ion become 35 and 3 Bq kg 1 , espec i ely, a ac o 4 highe han he Fig. 5. 127 I concen a ion ( m gg 1 )inFucus esiculosus om he Bal ic Sea in 1982 (black) and 1986 ( ed), and salini y (mean annual alues o he pe iod 1900e2005 o 1110 m size cells, aken om Feis el e al. (2010)). [Fo in e p e a ion o he e e ences o colou in his figu e legend, he eade is e e ed o he web e sion o his a icle.] Fig. 6. 129 I concen a ions in seawa e in he di e en sampling si es in e ed by concen a ion ac o s o 127 I. J.M. Gómez-Guzmán e al. / Jou nal o En i onmen al Radioac i i y 115 (2013) 134e142 139 le els measu ed in 1982 (and likely highe han he p e-Che nobyl le els, due o he known dec easing end in 137 Cs eleases om Sellafield and Cap de la Hague). Finally, 137 Cs concen a ion in Fucus in samples 29e33 emained a he le el o he p e ious mean alue, which in u n sugges s ha he high concen a ions o 129 I ound in his a ea should be ela ed o he e fluen s om he wo ep oc- essing plan s. The concen a ion ac o s o 137 Cs in F. esiculosus a ies widely om si e o si e in he Bal ic Sea (HELCOM, 2009), mos likely linked o changes in salini y. This could mask o some ex en he in o - ma ion om iso opic a ios. Thus, 137 Cs concen a ions in seawa e ha e been es ima ed om hei ecommended concen a ion ac o s in F. esiculosus in he di e en egions co e ed by he sampling campaign (HELCOM, 2009; concen a ion ac o s anging om 188 39 L kg 1 d y weigh in Ka ega o 453 145 L kg 1 in he wes e n Bal ic Sea and 622 100 L kg 1 in he Bo hnian Sea). This allows es ima ion o he 129 I/ 137 Cs iso opic a ios in bo h ma ices, F. esiculosus and seawa e using, o he las one, he ollowing equa ion, 129I 137CsW ¼129I 127IF ½ 127IWCFð137CsÞ ½137CsF whe e: [ 129 I/ 137 Cs] W is he 129 I/ 137 Cs a om a io in seawa e a he a ious Fucus sampling si es; [ 129 I/ 127 I] F is he a om a io in Fucus, using 129 I and 127 I concen a ions ob ained in his wo k, and assuming i o be he same as he [ 129 I/ 127 I] a io in seawa e (Hou e al. (2000b)); [ 127 I] W is he s able iodine concen a ion in coas al wa e a ound Sweden, aken om salini y da a (Figs. 3 and 4); [ 137 Cs] F is he 137 Cs concen a ion in Fucus gi en by Ca lson and Holm (1992) and CF( 137 Cs) is he ecommended concen a ion ac o o adiocaesium om seawa e o Fucus in Swedish coas al wa e s gi en by HELCOM (2009). These a ios a e shown in Fig. 7. F om he es ima ed composi ion o he Che nobyl emissions (Hou e al., 2002), he expec ed 129 I/ 137 Cs iso opic a io was 0.18, much lowe han he alues depic ed in Fig. 7. P e ious le els o 137 Cs concen a ions in seawa e con ibu e o dec ease his a io, while he p e ious exis ing le els o 129 I inc ease i . I he dis ibu ion and deposi ion o bo h iso opes did no la gely di e , he iso opic a ios in seawa e depic ed in Fig. 7 ha e o be unde s ood in e ms o he ela i ely low con ibu ion o 129 I om Che nobyl o enhance p e iously exis ing le els (as shown in Fig. 6), wha also has been epo ed elsewhe e (Hou e al., 2002;Bu aglio, 2000). Fu he mo e, om Fig. 7 i can be concluded ha as he de ia ion o his iso opic a io in seawa e becomes la ge wi h espec o he 1982 le els, he highe will be he local a mosphe ic deposi ion o he Che nobyl e fluen s. Again we can see ha o samples 29e33, he iso opic a io emains a he same le el as ha in 1982, which sugges s ha he o igins o 129 I in his egion a e he Sellafield and Cap de La Hague ep ocessing plan s. The 129 I/ 137 Cs iso opic a ios in F. esiculosus a e media ed by he di e en concen a ion ac o s ( hose o 129 I being on a e age, la ge by a ac o 20 han hose o 137 Cs) and by hei di e en ends o a ia ion wi h salini y (concen a ion ac o s o 129 I sligh ly inc ease wi h inc easing salini y, while hose o 137 Cs sha ply dec ease wi h inc easing salini y). In ac , hese da a can be used o in e a ela ionship o he concen a ion ac o o 137 Cs in F. esiculosus as a unc ion o he salini y in he Bal ic Sea a ea, ollowing a logelog ela ionship (R 2 ¼0.79, confidence le el 99%; da a se o 1986): log ½CFCs¼3:55 1:03log ½S This ela ionship can be unde s ood in e ms o he e ec o compe i i e ions (Ab il and F aga, 1996). E ec i ely, 137 Cs is usually p esen in seawa e as a mono alen ca ion a ace concen a- ions, in compe i ion wi h he dominan ca ions Na þ and K þ , whose concen a ions inc ease wi h salini y. I is wo h no ing in con as ha iodine exis s in seawa e mainly as dissol ed anions ioda e and iodide (Hou e al., 2001). F om da a shown in Table 1 i can be seen ha he 137 Cs concen a ions in seaweed samples collec ed in 1986 a e much highe han hose collec ed in 1982. This also explains he ac ha he a omic a ios 129 I/ 137 Cs in he Bal ic Sea shown in Fig. 7 we e highe in 1982 han in 1986. This was because he deposi ion o addi ional 137 Cs om he Che nobyl acciden was much mo e impo an han he addi ional 129 I deposi ion om he same sou ce. The highes 137 Cs ac i i y concen a ion in 1986 was obse ed a loca ion 1, he no he nmos locali y, and adjacen o he land a ea which ecei ed he highes allou deposi ion in Sweden om he Che nobyl acciden (Ca lson and Holm, 1992). The unexpec ed high 137 Cs ac i i y concen a ion ound a locali ies 24 and 26 could be influenced by he nea ly p esence o wo nuclea powe plan s, loca ed a Ba sebäck and Oska shamn, bo h eleasing 137 Cs in he d ainage a ea o he Bal ic Sea. Conce ning o he possible con ibu ions o 129 I and 137 Cs in his a ea, a ound he Bal ic Sea he e a e nuclea powe plan s in Sweden, Finland, Russia, Li huania and Ge many (as shown in Fig. 2) ha could di ec ly o indi ec ly elease 129 I and 137 Cs o i s d ainage a ea. No da a o 129 I discha ge om hese powe plan s a e a ailable, bu some au ho s (Bu aglio, 2000;Hou e al., 1999b, 2002) ha e concluded ha hei con ibu ion o he 129 I in en o y in he Bal ic Sea is insignifican . HELCOM (2009) has de e mined he o al aqua ic 137 Cs discha ges om hese local nuclea acili ies in o he Bal ic Sea o be 2.4 TBq un il he end o 2006, compa ed o he 4700 TBq eleased om he Che nobyl acciden in he same a ea. So he con ibu ion o hese acili ies o he o al in en o y o 137 Cs in he Bal ic Sea a ea is also insignifican , al hough some au ho s ha e ela ed 137 Cs concen a ions measu ed in Fucus collec ed nea Ba sebäck nuclea powe plan wi h i s eleased cooling wa e (E landsson and Ma sson, 1988;Ma sson e al., 1980). F om ou p esen esul s, i is clea ha he mos impo an con ibu ion o he 129 I in en o y in he Bal ic Sea a ea comes om he eleases o he wo ep ocessing acili ies a Sellafield and La Fig. 7. 129 I/ 137 Cs a om a io in seawa e (open ci cles and squa es) and in Fucus es- iculosus (filled ci cles and squa es) a he a ious sampling si es o 1982 (black) and 1986 ( ed). Unce ain ies come om he e o p opaga ion heo y. [Fo in e p e a ion o he e e ences o colou in his figu e legend, he eade is e e ed o he web e sion o his a icle.] J.M. Gómez-Guzmán e al. / Jou nal o En i onmen al Radioac i i y 115 (2013) 134e142140 Hague. HELCOM (2009) has also es ima ed he o al inpu o 137 Cs o igina ing om hese wo nuclea ep ocessing plan s o be 250 TBq, which is e en less han he 137 Cs eleased as a esul o allou om a mosphe ic nuclea weapon es s (620 TBq calcula ed o 1981). Thus, o his adionuclide he mos impo an sou ce o he in en o y in he Bal ic Sea a ea is he Che nobyl acciden . 6. Conclusions 129 I and 129 I/ 127 I a ios in seaweed samples F. esiculosus collec ed in 1982 (du ing he mon h o Oc obe ) and 1986 (du ing he mon h o July) ha e been measu ed. Fo bo h yea s, 129 I/ 127 I a ios a e much highe han expec ed o p e-nuclea e a (be ween 10 12 and 6 10 13 ) and due o a mosphe ic nuclea weapons es ing (10 10 ). These le els accoun o <0.05% and <5% o he o al 129 I in en o y in his egion espec i ely. A linea ela ionship has been es ablished o 127 I concen a ions in seawa e and salini y in he Bal ic Sea, enabling he es ima ion o concen a ion ac o s o 127 IinF. esiculosus, anging om 2500 o 13,300, and showing a sligh ly dec easing end wi h salini y. I has been assumed ha hese concen a ion ac o s equally apply o 129 I, enabling he econs uc ion i s concen a ions in seawa e and he s udy o hei spa ial dis ibu ion. The high le els o 129 I and 129 I/ 127 I in he Ka ega and hei g adually dec ease owa ds he Bal ic Sea indica e ha he 129 I discha ged om he ep ocessing plan s a Sellafield and La Hague has been anspo ed o he Ka ega om he No h Sea and pa ly u he anspo ed o he Bal ic Sea ia he Bel Sea. Hence, he mos impo an con ibu ion o he 129 I in en o y in he Bal ic Sea a ea comes om he eleases o bo h ep ocessing plan s. This esul was also suppo ed by he 129 I/ 137 Cs a ios in F. esiculosus and seawa e . This a io in Fucus was media ed by concen a ion ac o s o 137 Cs, which dec eased wi h salini y as a esul o he e ec o he dominan compe i i e ca ions. Wi h espec o he Che nobyl acciden , 129 I concen a ions in samples collec ed in 1986 a e no much highe han hose expec ed in less con amina ed samples om 1982. This suppo s he iew ha he con ibu ion o he Che nobyl acciden o 129 I in he Bal ic egion was no significan . In con as , he 137 Cs ac i i y concen- a ions in samples collec ed in 1986 a e much highe han hose in co esponding samples collec ed in 1982, confi ming ha he Che nobyl acciden was he main sou ce o 137 Cs o he Bal ic Sea a ea. Acknowledgemen s The au ho s would like o hank he Swedish Radia ion P o ec- ion Au ho i y (SSM), Spanish Minis y o Science and Technology (FIS2008-01149) and he Jun a de Andalucía (EXC/2005/RNM-419) o hei financial suppo . The au ho s a e also e y hank ul o D . Elis Holm o p o iding he seaweed samples. Re e ences Ab il, J.M., F aga, E., 1996. Some physical and chemical ea u es o he a iabili y o kd dis ibu ion coe ficien s o adionuclides. Jou nal o En i onmen al Radio- ac i i y 30, 253e270. Aldahan, A., Kekli, A., Possne , G., 2006. Dis ibu ion and sou ces o 129 I in i e s o he Bal ic Sea. Jou nal o En i onmen al Radioac i i y 88, 49e73. Aldahan, A., Alfimo , V., Possne , G., 2007. 129 I an h opogenic budge : majo sou ces and sinks. Applied Geochemis y 22, 606e618. Alfimo , V., Aldahan, A., Possne , G., Winso , P., 2004. An h opogenic iodine-129 in seawa e along a ansec om he No wegian coas al cu en o he No h Pole. Ma ine Pollu ion Bulle in 49, 1097e1104. A c ic Pollu ion Issues: A S a e o he A c ic En i onmen Repo , 2003. Chap e 3, A c ic Moni o ing and Assessmen P og amme. A e a Rappo En i onnemen , 2006. The En i onmen al Moni o ing P og am, Annual Repo . A e a L d. B an , J., Ch is ensen, J.H., F ohn, L.M., 2002. Modeling anspo and deposi ion o caesium and iodine om he Che nobyl acciden using he DREAM model. A mosphe ic Chemis y and Physics 2, 397e417. Bu aglio, N., 2000. Accele a o Mass Spec ome y o 129 I and i s applica ion in na u al wa e sys em. PhD hesis, Uppsala Uni e si y. Ca lson, L., Holm, E., 1992. Radioac i i y in Fucus esiculosus L. om he Bal ic Sea ollowing he Che nobyl acciden . Jou nal o En i onmen al Radioac i i y 15, 231e248. CEC (Commission o he Eu opean Communi ies), 1991. P oceeding o Semina on Compa a i e Assessmen o he En i onmen al Impac o Radionuclides Released du ing Th ee Majo Nuclea Acciden s: Kysh ym, Windscale, Che - nobyl, ol. I and II. EUR 1374. Chai, Z.F., Zhu, H.M., 1994. In oduc ion o T ace Elemen s Chemis y. A omic Ene gy P ess, Beijing, pp. 84e85. Coope , L.W., Beasley, T.M., Zhao, X.L., So o, C., Vinog ado a, K.H., Dun on, J., 1998. Iodine-129 and plu onium iso opes in A c ic kelp as his o ical indica o s o anspo o nuclea uel- ep ocessing was es om mid- o-high la i udes in he A lan ic Ocean. Ma ine Biology 131, 391e399. D uehl, L.D., Cacke e, M., D’Au ia, J.M., 1988. Geog aphical and empo al dis ibu- ion o iodine-131 in he b own seaweed Fucus subsequen o he Che nobyl acciden . Ma ine Biology 98, 125e129. Edmonds, H.N., Smi h, J.N., Li ings on, H.D., Kilius, L.R., Edmond, J., 1998. I-129 in a chi ed seawa e samples. Deep Sea Resea ch I 45, 1111e1125. Eisenbud, M., Gesell, T., 1997. En i onmen al Radioac i i y. Academic P ess, San Diego. E landsson, B., Ma sson, S., 1988. Up ake o d y-deposi ed adionuclides in Fucus- afield s udy a e he Che nobyl acciden . Jou nal o En i onmen al Radioac- i i y 6, 271e281. Fab yka-Ma in, J.T., Ben ley, H., Elmo e, D., Ai ey, P.L., 1985. Na u al iodine-129 as an en i onmen al ace . Geochimica and Cosmochimica Ac a 49, 337e347. Feis el, R., Wein eben, S., Wol , H., Sei z, S., Spi ze , P., Adel, B., Nausch, G., Schneide , B., W igh , D.G., 2010. Densi y and absolu e salini y o he Bal ic Sea 2006e2009. Ocean Science 6, 3e24. F échou, C., Calme , D., 2003. 129 I in he en i onmen o he La Hague nuclea uel ep ocessing plan - om sea o land. Jou nal o En i onmen al Radioac i i y 70, 43e59. Gallaghe , D., McGee, E., Mi chell, P.I., Alfimo , V., Aldahan, A., Possne , G., 2005. Re ospec i e sea ch o e idence o he 1957 Windscale fi e in NE I eland using 129 I and o he long-li ed nuclides. En i onmen al Science and Technology 39, 2927e2935. Gómez-Guzmán, J.M., Enamo ado-Báez, S.M., Pin o-Gómez, A.R., Ab il- He nández, J.M., 2011. Mic owa e-based diges ion me hod o ex ac ion o 127 I and 129 I om solid ma e ial o measu emen s by AMS and ICP-MS. In e na- ional Jou nal o Mass Spec ome y 303, 103e108. Gómez-Guzmán, J.M., López-Gu ié ez, J.M., Pin o-Gómez, A.R., Holm, E., 2012. 129 I measu emen s on he 1 MV AMS acili y a he Cen o Nacional de Acele ado es (CNA, Spain). Applied Radia ion and Iso opes 70, 263e268. G ay, J., Jones, S.R., Smi h, A.D., 1995. Discha ges o he en i onmen om he Sellafield si e, 1951e1992. Jou nal o Radiological P o ec ion 15, 99e131. HELCOM, 2009. Radioac i i y in he Bal ic Sea, 1999e2006. In: Bal ic Sea En i on- men P oceedings, ol. 117. Helsinki Commission, Bal ic Ma ine En i onmen P o ec ion Commission, Helsinki. Hou, X.L., Yan, X.J., 1998. S udy on he concen a ion and seasonal a ia ion o ino ganic elemen s in 35 species o ma ine algae. Science o he To al En i- onmen 222, 141e156. Hou, X.L., Dahlgaa d, H., Rie z, B., Jacobsen, U., Nielsen, S.P., Aa k og, A., 1999a. De e mina ion o 129 I in seawa e and some en i onmen al ma e ials by neu on ac i a ion analysis. Analys 124, 1109e1114. Hou, X.L., Dahlgaa d, H., Rie z, B., Jacobsen, U., Nielsen, S.P., Aa k og, A., 1999b. De e mina ion o chemical species o iodine in seawa e by adiochemical neu on ac i a ion analysis combined wi h ion-exchange p esepa a ion. Analy ical Chemis y 71, 2745e2750. Hou, X.L., Dahlgaa d, H., Nielsen, S.P., Ding, W.J., 2000a. Iodine-129 in human hy oids and seaweed in China. Science o he To al En i onmen 246, 285e291. Hou, X.L., Dahlgaa d, H., Nielsen, S.P., 2000b. Iodine-129 ime se ies in Danish, No wegian and No hwes G eenland Coas and he Bal ic Sea by seaweed. Es ua ine, Coas al and Shel Science 51, 571e584. Hou, X.L., Dahlgaa d, H., Nielsen, S.P., 2001. Chemical specia ion analysis o 129 Iin seawa e and a p elimina y in es iga ion o use i as a ace o geochemical cycle s udy o s able iodine. Ma ine Chemis y 74, 145e155. Hou, X.L., Dahlgaa d, H., Nielsen, S.P., Kuce a, J., 2002. Le el and o igin o Iodine-129 in he Bal ic Sea. Jou nal o En i onmen al Radioac i i y 61, 331e343. IAEA, 1986. S udy o Radioac i e Ma e ials in he Bal ic Sea. IAEA TECDOC-362. In e na ional A omic Ene gy Agency, Vienna, 189 pp. Kilius, L.R., Li he land, A.E., Rucklidge, J.C., Baba, N., 1992. Accele a o mass spec- ome y measu emen s o hea y long-li ed iso opes. Applied Radia ion and Iso opes 43, 279e287. Klein, M.G., Mous, D.J.W., Go dang, A., 2006. A compac 1 MV mul i-elemen AMS sys em. Nuclea Ins umen s and Me hods in Physics Resea ch, Sec ion B: Beam In e ac ions wi h Ma e ials and A oms 249, 764e767. Klein, M.G., Van S a e en, H.J., Mous, D.J.W., Go dang, A., 2007. Pe o mance o he compac HVE 1 MV mul i-elemen AMS sys em. Nuclea Ins umen s and Me hods in Physics Resea ch, Sec ion B: Beam In e ac ions wi h Ma e ials and A oms 259, 184e187. J.M. Gómez-Guzmán e al. / Jou nal o En i onmen al Radioac i i y 115 (2013) 134e142 141 Leh o, J., Rä y, T., Hou, X.L., Paa e o, J., Aldahan, A., Possne , G., Flinkman, J., Kankaanpäa, H., 2012. Specia ion o 129 I in sea, lake and ain wa e s. Science o he To al En i onmen 419, 60e67. López-Gu ié ez, J.M., Ga cía-León, M., Schnabel, Ch., Su e , M., Synal, H.A., Szida , S., Ga cía-Teno io, R., 2004. Rela i e influence o 129 I sou ces in a sedimen co e om he Ka ega a e. Science o he To al En i onmen 323, 195e210. Ma sson, S., Fink, R., Nilsson, M., 1980. Dis ibu ion o ac i a ion p oduc s om Ba seback nuclea powe plan (Sweden) in he ma ine en i onmen : empo al and spa ial a ia ions as es ablished by seaweed. En i onmen al Pollu ion B1, 105e115. Moni o ing ou En i onmen , 2006. Discha ges and Moni o ing in he UK, Annual Repo . Sellafield L d. NCRP (Na ional Council on Radia ion P o ec ion and Measu emen ), 1983. Iodine- 129: E alua ion o Releases om Nuclea Powe Gene a ion. NCRP epo No. 75. Nielsen, S.P., Kei h-Roach, M., 2004. Upda e o he MARINA P ojec on he Radio- logical Exposu e o he Eu opean Communi y om Radioac i i y in No h Eu opean Ma ine Wa e s, Annex E: C i ical g oup exposu e. Eu opean Commission epo , 30 pp. Nielsen, S.P., Beng son, P., Bojanowki, R., Hagel, P., He mann, J., Ilus, E., Jakobson, E., Mo iejunas, S., Pan elee , Y., Skujina, A., Suplinska, M., 1999. The adiological exposu e o man om adioac i i y in he Bal ic Sea. Science o he To al En i onmen 237e238, 133e141. Os e c, J., S ibilj, V., 2008. 127 I and 129 I/ 127 I iso opic a io in ma ine alga Fucus i - soides om he No h Ad ia ic Sea. Jou nal o En i onmen al Radioac i i y 99, 757e765. Pen ea h, R.J., 1985. Gene al e iew o li e a u e ele an o wa e discha ges. IAEA- TECDOC-329. In: Beha io o Radionuclides Released in o Coas al Wa e s. In e na ional A omic Ene gy Agency. Po inec, P.P., Fowle , S.W., Bax e , M.S., 1996. Che nobyl and he ma ine en i on- men : he adiological impac in con ex . IAEA Bulle in 1, 22. Po inec, P.P., Du Bois, P.B., Ke shaw, P.J., Nies, H., Sco o, P., 2003. Tempo al and spa ial ends in he dis ibu ion o 137 Cs in su ace wa e s o No he n Eu o- pean Seas ea eco d o 40 yea s o in es iga ions. Deep Sea Resea ch II 50, 2785e2801. Raisbeck, G.M., Yiou, F., Zhou, Z.Q., Kilius, L.R., 1995. 129 I om nuclea ep ocessing acili ies a Sellafield (UK) and La Hague (F ance): po en ial as an oceanog aphic ace . Jou nal o Ma ine Sys ems 6, 561e570. Rao, U., Fehn, U., 1999. Sou ces and ese oi s o an h opogenic Iodine-129 in wes e n New Yo k. Geochimica and Cosmochimica Ac a 63, 1927e1938. Robe s, M.L., Ca ee, M.W., P oc o , I.D., 1997. 129 I in e labo a o y compa ison. Nuclea Ins umen s and Me hods in Physics Resea ch, Sec ion B: Beam In e - ac ions wi h Ma e ials and A oms 123, 367e370. Salo, A., Tuomainen, K., Voipio, A., 1986. In en o ies o some long-li ed adionu- clides in he Bal ic Sea. Science o he To al En i onmen 54, 247e260. Toscano, M., Ga cía-Teno io, R.A., 2004. Th ee-Dimensional model o he dispe - sion o adioac i e subs ances in ma ine ecosys ems. Applica ion o he Bal ic Sea a e he Che nobyl disas e . Ocean Enginee ing 31, 999e1018. Vi es i Ba lle, J., Wilson, R.C., McDonald, P., 2007. Allome ic me hodology o he calcula ion o biokine ic pa ame e s o ma ine bio a. Science o he To al En i onmen 388, 256e269. Vi es i Ba lle, J., Wilson, R.C., Wa s, S.J., Jones, S.R., McDonald, P., Vi es-Lynch, S., 2008. Dynamic model o he assessmen o adiological exposu e o ma ine bio a. Jou nal o En i onmen al Radioac i i y 99, 1711e1730. Wagne , M.J.M., Di ich-Hannen, B., Synal, H.A., Su e , M., Scho e e , U., 1996. Inc ease o 129 I in he en i onmen . Nuclea Ins umen s and Me hods in Physics Resea ch, Sec ion B: Beam In e ac ions wi h Ma e ials and A oms 113, 490e494. J.M. Gómez-Guzmán e al. / Jou nal o En i onmen al Radioac i i y 115 (2013) 134e142142