21ºPb enhancemen in i e s a ec ed by he phospha e
ock p ocessing in sou hwes e n Spain
A. Ma ínez-Agui e and M. Ga cía-León
Facul ad de Física, Uni e sidad de Se illa, Apdo. 1065, 41080 Se illa, Spain
ABSTRACT
The ac i i y le els o 21ºPb in solu ion and bo om sedimen a we e measu ed in he
es ua y o med by he Odiel and Tin o i e a in sou hwes Spain. The le els in bo h
wa e and sedimen samples indica e ha he discha ges om wo e ilize ac o ies
in he a ea enhance he adioac i i y o such samples.
l. INTRODUCTION
Recen ly, high adioac i i y le els o U, Th and 226Ra iso opes we e ound in
solu ion, suspended ma e and bo om sedimen s o he Odiel and Tin o i e s
loca ed in sou hwes em Spain [l-3]. The anomaly was a ibu ed o wo e il
ize ac o ies loca ed in an indus ial complex su ounded by hese wo i e s
(Fig. 1). These ac o ies elease hei was es di ec ly o he Odiel i e o s o e
hem in unco e ed piles nea he Tin o i e channel. In his pape , we ha e
ex ended p e ious wo k o he s udy o 210Pb in solu ion and bo om sedimen s.
2. SAMPLES AND EXPERIMENTAL METHODS
Se en poin s on he Odiel i e , ou on he Tin o i e and one a he con lu
ence o bo h i e s (Fig. 1) we e sampled o wa e and bo om sedimen s in
July 1990 (d y season) and in Feb ua y 1991 (we season) o e alua e seasonal
a ia ions in 21ºPb ac i i ies. The pH o he wa e s was measu ed a he ime
o sampling. The suspended ma e was sepa a ed by il a ion h ough Nu
cleopo e il e s o 0.45 µm po e size. Immedia ely, he il a e was acidi ied o
pH -2 wi h concen a ed HNOa, The small size ac ion (d < 63 µm) was
sepa a ed om sedimen samples in o de o de e mine he 21ºPb con en .
De e mina ions o pe cen o ganic ma e and pe cen o wa e we e ca ied
ou on each bo om sedimen sample.
N
� PHOSPHOGYPSUM PILES
0 FERTILIZER INDUSTRIES
o 3km
Fig. l. Map o he Odiel and Tin o i e s which shows he sampling s a ions along bo h i e
channels. The e ilize ac o ies and he phosphogypsum s o age a ea a e also shown.
21ºPb was de e mined h ough he measu emen o i s daugh e 21ºPo by
cx-spec ome y, a le secula equilib ium was achie ed. The samples we e
spiked wi h known ac i i ies o 208Po o de e mine he chemical eco e y o he
o al p ocedu e. Samples we e i s acid diges ed wi h concen a ed HN08
ollowed by aqua egia and, inally dissol ed in 8 M HN08• Po was sepa a ed
using a sol en ex ac ion me hod wi h TBP as he o ganic phase and 8 M
HN03 as he ino ganic phase. A e igo ous shaking Po emains in he
ino ganic phase whe eas o he adionuclides join he o ganic phase. The
solu ion con aining he Po was e apo a ed o d yness and sel deposi ion o Po
on o sil e planche s was encou aged by shaking gen ly a 60ºC. The planche
was inally measu ed by cx-spec ome y wi h ion implan ed de ec o s. Fu he
de ails on he adiochemical p ocedu e a e p esen ed in Mo ón e al. [ 4).
3. RESULTS AND DISCUSSION
To simpli y he subsequen discussion we will i s p esen he esul s o wa e
samples om bo h i e s o all sampling campaign.s, ollowed by hose ob
ained o bo om sedimen s. Samples O ep esen hose alcen in he Odiel
i e , T in he Tin o i e and OT in he con luence o bo h i e s. Sedimen
samples a e iden i ied as SO, ST and SOT o he Odiel, Tin o and he con lu
ence espec i ely. The index ep esen s he sampling s a ion along each i e
(Fig. 1).
3.1. Wa e s
The esul s ob ained o he analysis o 210Pb in wa e samples alcen du ing he
low ide in 1990 (d y season) and 1991 (we season) a e p esen ed in Table l.
The le els o 21ºPb in he Odiel i e a ea unde s udy ange om 3. 7 ± 0.5 o
289 ± 22 mBq 1-1 wi h he maxima, in summe and in win e , in on o one o
he e ilize ou alls (Fig. 2). The le els dec ease quickly downs eam om his
poin , due, p obably, o p ecipi a ion o Fe and Mn du ing mixing downs eam
[5]. This ac i i y pa e n is simila o hose ob ained p e iously o o he
adionuclides [1,2) e lec ing he p esence o a local sou ce o adioac i i y ( he
e ilize indus ies) along he i e channel. The minimum le els ound in sum
me a e clea ly highe han hose in win e , p obably due o a lowe wa e s eam
low o he i e in he d y season. In he case o he Tin o i e he le els along
he channel a e qui e cons an , anging om 17.0 ± 1.5 o 26.6 ± 3.0 mBq 1-1 in
summe 1991, wi h a sligh dec ease downs eam o he channel. In 1991, he
le els ange om 15.3 ± 3.1 o 45.6 ± 2.7 mBq 1-1• In bo h campaigns he
TABLE I
Da a o 21ºPb in mBq 1-1 in wa e samples (low ide) aken om he Odie! and Tin o i e basins
in 1990 (d y season) and 1991 (we season). The pH o he wa e s a he ime o sampling is also
gi en. N.M means no measu ed
1990 1991
Code pH 210pb pH 210pb
01 2.86 21.1±2.5 3.90 N.M.
02 6.37 7.9±1.0 5.52 7.8±0.7
03 6.42 10.2±3.4 5.90 3.7±0.5
04 6.35 289±22 5.96 36.4±2.6
05 6.32 34.4±2.2 6.03 8.4±0.8
06 6.48 12.2±1.4 6.06 7.4±1.1
07 6.40 14.0±1.0 6.02 50.6±3.9
Tl 2.41 41.7±3.1 2.88 N.M.
T2 5.54 26.6±3.0 3.22 45.6±2.7
T3 5.82 19.5±1.5 5.56 15.3±3.1
T4 6.10 17.0±1.5 6.40 30.7±5.7
OT 6.56 11.7±1.0 6.23 10.5±1.2
º'
Odlel and Tin o wo e s
02 03 04 05 06 07
----1990
- - -- --1991
OT T4 T3 T2 T1
Fig. 2. 210pb in mBq 1-1 in wa e samples aken om he Odiel and Tin o i e s in 1990 and
1991.
maximum le el in he Tin o i e was ound in s a ion T2. This s a ion is
loca ed close o an a i icial s eam coming om he · phosphogypsum s o age
a ea. In ac , he pH o he wa e a his s a ion is lowe han a he es o he
s a ions, a 3.22 in 1991 (Table 1), which e lec s he was es eleased a his
poin . We also obse e ha he le el o 210Pb ound a s a ion T4 o he Tin o
i e is qui e simila o ha ound a s a ion 07 o he Odiel i e . This ac could
be explained by he in luence ha con amina ed wa e s om he Odiel i e ha e
on he Tin o i e channel. Thus, con amina ed wa e om he Odiel i e can low
ups eam in o he Tin o i e when he ide changes om low o high.
In he Ne he lands, Kos e e al. [6] ob ained le els o 210Pb o 0.9 mBq 1-1 in
wa e s o he Oos e chelde sys em while in he a ea a ound a e ilize ac o y
in he Nieuwe Wa e weg sys em hey ound 10 mBq 1-1. In gene al, he au ho s
assumed le els below 1 mBq 1-1 as a backg ound le el, hose highe han 3 mBq
1-1 as p obably enhanced and inally, hose highe han 5 mBq 1-1 as clea ly
enhanced. Lewis [5] epo ed dissol ed 21ºPb in no mal i e wa e s o be less
han 0.2 mBq 1-1• By con as in acid i e wa e s, dissol ed 210Pb was ound o
each 230 mBq 1-1 in he Colo ado sys em and 2.8 mBq i-1 in he wes b anch
o he Susquehannah i e [7]. Compa ing he le els o
21ºPb in he Odiel and
Tin o i e s o bo h sampling campaigns we should conside bo h i e s o be
clea ly enhanced in 210Pb ac i i y by he e ilize indus ies, pa icula ly in he
a ea close o he ou alls. The backg ound le el away om he ou alls appea s
o be a ound 7 mBq 1-1•
We will conside sepa a ely he case o samples 01 and Tl, which we e
collec ed a he sou ce o bo h i e s, a om he e ilize indus ies (20 km
ups eam in bo h cases) and una ec ed by hei was es. Bo h sampling s a ions
p esen le els o
210Pb much highe han he usual alues in esh i e wa e s.
This ac mus be ela ed wi h he acid pH o he wa e s (Table 1) a bo h
s a ions. These acid pHs p oduce a dissolu ion o
210Pb om soil pa icles and
consequen ly a highe 21ºPb ac i i y in solu ion, as was p e iously ound in he
Colo ado i e and in he Susquehannah i e (6, 7]. This e ec o dissolu ion
om bo om sedimen s by he acid pH o he wa e s was also ound o o he
adionuclides in he same sampling s a ions (1-3).
3.2. Sedimen s
The small size ac ion (d::;; 63 µm) o 7 bo om sedimen s om he Odiel i e ,
4 om he Tin o and 1 om he con luence o bo h i e s sampled in 1990 and
1991 we e sepa a ed o 210Pb de e mina ions. The esul s ob ained oge he
wi h pe cen o wa e and pe cen o o ganics o each sedimen sample a e
p esen ed in Table 2.
Le els o 21ºPb a e qui e high in he a ea close o he e ilize indus ies in
he Odiel i e , wi h a maximum le el o 799 ± 48 mBq g-1 in 1990 and 534 ±
25 mBq g-1 in 1991. These le els o adioac i i y a s a ions 04 o 07 a e much
highe han he backg ound le el, ::;;100 mBq g-1 epo ed elsewhe e [6]. Only
in wo s a ions (Fig. 3), ups eam om he indus ies, in bo h sampling
campaigns, does he le el o 210Pb all in he non enhanced ange (::;;100 mBq g-1).
210Pb ac i i y le els a s a ion 07 we e much lowe (::;;100 mBq g-1) in he 1990
TABLE2
Da a o 210Pb in mBq g-1 in he small size ac ions o bo om sedimen a aken om he Odie! and
Tin o i e basins in 1990 (d y season) and 1991 (we season). Pe cen o wa e and pe cen o
o ganice in he sedimen samples a e siso gi en. N.M. means no measu ed
Code %Wa e % O ganics 210pb %Wa e % O ganice 210pb
S01 52.58 5.73 N.M. 61.18 15.40 N.M.
S02 26.64 11.76 13.9±1.3 24.53 3.09 8.0±0.7
S03 60.58 9.51 27.2±1.5 57.21 8.25 40.9±2.7
S04 52.53 10.91 212±10 39.13 11.57 284±14
S05 65.51 5.26 438±21 59.83
9.74
420±31
S06 58.18
9.47
799±49 67.93 12.95 534±25
S07 65.35
9.47
78.6±3.7 55.64 9.58 411±24
STl 79.63 8.38 N.M. 39.80 2.25 N.M.
ST2 38.78 4.34 96.7±6.1 51.37 8.96 33.1±3.3
ST3 59.29 9.64 39.8±1.9 56.8 11.72 233±9
ST4 61.46 8.64 74.4±4.8 56.03 10.93 47.9±2.5
OT 64.98 8.69 149±11 66.77 11.49 204±16

Odlel and Tin a 1edlmen 1
502 503 504 S011 508 507
___ 1990
------1991
se S 4 5 3 S 2
Fig. 3. 21°Fb in mBq g-1 in bo om sedimen samples aken om he Odiel and Tin o i e s
in 1990 and 1991.
sampling campaign han in ha o 1991. This mus be ela ed o so ne d ainage
ac i i ies ca ied ou in he a ea in 1990.
In he Tin o i e he le els ange om 33.1 ± 3.3 o 233 ± 9 mBq g-1 in he
ine ac ion o bo h yea s. 21ºPb le els in he Tin o i e sedimen s, o he
same sampling campaigns, a e much lowe han in he Odiel i e . Mo eo e ,
he e is a clea peak o ac i i y in s a ion T3 in he sampling campaign o 1991
(Fig. 3), wi h le els much highe han he ypical backg ound le el. This s a ion
is loca ed a he con luence wi h a small na u al s eam, Es e o del Rincón,
(Fig. 1) which c osses he phosphogypsum s o age a ea, and could anspo
so ne gypsum pa icles wi h high ac i i y le els. These pa icles will e en ually
be deposi ed on he Tin o i e bed a he con luence. High ac i i y le els o
o he na u al adionuclides we e also ound a he same s a ion in 1988 and
1989 [1,2]. The s a ions ups eam om he indus ies a he Odiel i e and
also s a ions ST2 and ST4 o he Tin o i e , howe e , p esen le els o 21ºPb
much lowe and simila o he backg ound le el (SlOO mBq g-1). In gene al, no
co ela ions be ween 210Pb con en and o ganic o g anula composi ion we e
ound in ei he i e , and he ac i i y pa ems ob ained a e simila o hose
ound o o he adionuclides in p e ious yea s [1,2].
4. ACKNOWLEDGEMENTS
The au ho s wish o hank J.M. Ab il, G. Manjon and J. Diaz o helping in he
sampling. The wo k was pa ially suppo ed unde con ac DGICYT PB89-
0621 and EEC con ac FI3P-CT920035.
5. REFERENCES
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Chem. Le ., 155: 97-106.
2. Ma ínez-Agui e, A., M. Ga cía-León and M. l ano ich, 1994. The dis ibu ion o
U, Th and 226Ra de i ed om he phospha e e ilize indus ies on an es ua ine
sys em in sou hwes Spaín. J. En i on. Radioac i i y, 22: 155-177.
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ion in solu ion and suspended ma e om i e s a ec ed by he phospha e ock
p ocessing in sou hwes e n Spain. Nucl. Ins um. Me h. Phys. Res. A, 339: 287-
293.
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ENS, Ba celona, p. 111.
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