The Dis ibu ion o U, Th and 226Ra De i ed om he
Phospha e Fe ilize Indus ies on an Es ua ine Sys em in
Sou hwes Spain
A. Ma ínez-Agui e, M. Ga cía-León
Facul ad de Física, Uni e sidad de Se illa, Apa ado 1065. 41080 Se illa, Spain
&
M. I ano ich
AEA En i onmen and Ene gy, Ha well Labo a o y, Oxon OXI 1 ORA. UK
ABSTRACT
This pape epo s an ex ensi e s udy o he p esence o na u al adioac i i y
a ound a phospha e e ilize ac o y complex sí ua ed in an es ua ine a ea
o sou hwes Spain. The s udy has concluded ha he was es om such indus ies a e
he cause o he enhancemen o na u al adioac i i y in he immedia e en i onmen .
Thus, signi ican ly high le els o U- and Th-iso opes and 226 Ra a e de ec ed in wa e
and sedimen samples collec ed in his a ea. These conclusions based on he enhanced
iso opic concen a ions a e u he suppo ed by he measu ed U, Th and Ra iso opic
ac i i y a ios being qui e di e en om any obse ed e sewhe e in undis u bed
es ua ies. These iso ope ac i i y a ios appea o be e y sensi i e indica o s o was e
disposal p ac ices in such en i onmen s.
INTRODUCTION
Recen ly, se e a! s udies ha e been ca ied ou in he icini y o phospha e
e ilize indus ies in a de o es ablish he signi icance o he adiological
impac o hei ope a ions on he en i onmen as well as on he human
popula ion (S ain, 1979; Van de Heidje e al., 1988; Kos e e al., 1991;
Ma ínez-Agui e & Ga cía-León, 1991a). While ypical ocks con ain on
a e age so ne 2·8 ppm o U (UNSCEAR, 1977), a phospha e ock can
con ain up o 50-300 ppm o U (Gascoyne, 1982). The Eu opean
Communi y impo s annually so ne 15-17 MT o phospha e ock
(Baes slé, 1991 ). The impo ed ma e ial is p ocessed in o di e en
p oduc s gene a ing was es such as phosphogypsum. Each yea 6-7 MT
o phosphogypsum is discha ged di ec ly in o he sea, and, in addi ion,
so ne 8-11 MT is deposi ed as so lid was es in piles (Baes slé, 1991 ). These
piles emain unp o ec ed om ainwa e , wind and o he elemen s, and
hus hey could be connec ed hyd aulically o su ace o g oundwa e s as a
po en ial sou ce o con amina ion.
The phosphogypsum is mainly composed o CaS04. This means ha i
also con ains U, Th and Ra in la ge quan i ies as a esul o co-p ecipi a ion
wi h Ca du ing he p ocess o e ilize p oduc ion. I is he e o e possible
ha na u al p ocesses could lead o he edis ibu ion o hese na u al
adionuclides in o he en i onmen su ounding he was e disposal si es.
S ain ( 1979) ound a signi ican inc ease o Ra ac i i ies in g ound
wa e s collec ed a ound a e ilize ac o y a No h Ca olina, USA. So ne
o he wo ke s (Van de Heidje e al., 1988; Kos e e al., 1991) ha e also
s udied he p esence o na u al adioac i i y, mainly 226Ra and 21 ºPo, in
Eu opean en i onmen s a ec ed by such indus ies. Also, Paul e al. (1980)
in es iga ed signi ican ly high 226Ra concen a ions in phosphogypsum a
Ke ala, India.
Recen ly, Ma ínez-Agui e and Ga cía-León (1991a) ound anoma
lously high U-iso ope ac i i ies in wa e and sedimen samples collec ed a
he Odie! and Tin o i e s in sou hwes Spain (Figs 1 and 2). Such
enhancemen s we e a ibu ed o an indus ial complex su ounded by
hese i e s in which wo phospha e e ilize ac o ies we e loca ed. One
ac o y p ocesses a ound 1-4 MT pe yea o phospha e ock om
Mo occo, while he o he uses a ound 0·2 MT o ock om Mo occo,
Senegal and Togo. Bo h ac o ies elease hei was es di ec ly o he Odie!
i e o a e s o ed in unco e ed piles ( he a ea ma ked wi h s a s in Fig. 2).
U sing he da a gi en by Guimond and Ha din (1989) o phospha e ock
om Mo occo, he i s ac o y alone may p oduce a ound 2-2 TBq o
226Ra, 2-3 TBq o 238U and 1 -4 TBq o 232Th each yea . Pa o his ac i i y
can ob iously be edis ibu ed o e he en i onmen ha su ounds he
indus ial complex.
This pape ep esen s a mo e comple e s udy o possible edis ibu ion o
he adioac i i y om he was es gene a ed by he abo e phospha e
e ilize ac o ies. To his pu pose iso opes o U and Th and 226Ra ha e
been ex ac ed and de e mined om di e en su ace wa e and sedimen
Medi e anean sea
Fig. l. Map o Spain showing he s udied a ea in he Andalousian egion.
collec ed du ing 1989. The adionuclide concen a ions in hese samples
and he co esponding ac i i y a ios, which e lec he daugh e s mobili y,
and p obably, also he o igin o he adionuclides, will be used o
in es iga e he dis ibu ion o adioac i i y o e his a ea o sou hwes e n
Spain.
SAMPLING AND EXPERIMENTAL METHODS
Samples o i e wa e and sedimen we e collec ed along he Odiel and
Tin o i e basins (Fig. 2) du ing July 1989. Su ace wa e samples o 7-1 O l
we e collec ed in plas ic bo les du ing low ide, and pH and empe a u e
(ºC) we e measu ed a he same ime. The suspended ma e was sepa a ed
as soon as possible using 0-45 µm po e size Nuclepo e il e s. I has been
p ese ed o u u e analysis, since i could p o ide in e es ing addi ional
in o ma ion. Then, he il a e was acidi ied o pH ""2 by concen a ed
HN03, o a oid he g ow h o mic oo ganisms and o minimize wa e /wall
in e ac ions. A he same ime, bo om sedimen s we e collec ed. Samples
o abou 1 kg we e collec ed and s o ed in plas ic bags. Then, in he
labo a o y, sub-samples we e d ied and powde ed be o e analysis.
The ex ac ion me hod used o U- and Th-iso ope sepa a e is gi en in
® Piles o phosphogypsum
O 3km
L____J__j
Fig. 2. Map o Odiel and Tin o i e s showing he sampling s a ions in 1989.
I ano ich and Mu ay (1992) and Ma ínez-Agui e (1991). Only a b ie
desc ip ion is gi en he e. A e homogeniza ion, a ew g ams o d y
sedimen , spiked wi h known quan i ies o 236U and 229Th s anda d
solu ions o chemical yield de e mina ions, a e diges ed wi h HN03, aqua
egia, HC104 and HF. The esidue le a e he abo e ea men is
dissol ed in 7M HN03. The U and Th a e co-p ecipi a ed wi h Fe3+ by
adding concen a ed ammonia o he solu ion. The U- and Th-iso opes a e
i s sepa a ed by using anion exchange esins (Dowex AG 1 X 8
hyd ochlo ic o m) condi ioned wi h 8M HCl. Then each ac ion is
u he pu i ied by he emo al o Fe whose p esence would a ec he .x
spec al esolu ion. Fo his las pu i ica ion s ep he esins in he
sepa a ion columns a e condi ioned wi h 7M HN03. These pu i ied
solu ions a e d ied and U and Th a e elec opla ed on o s ainless s eel
planche s using he p ocedu e o Lally and Eakins (1978). The ac i i ies a e
de e mined by a-spec ome y using su ace ba ie Si a-de ec o s.
In he case o wa e samples, so ne 7-101 o wa e a e spiked wi h 236U
and 229Th s anda d solu ions and hen boiled down o app oxima ely 11.
The U and Th con en is hen co-p ecipi a ed wi h Fe3
+ by he addi ion
o (NH)40H. The p ecipi a e, a e sepa a ion om supe na e by con i
uging, is dissol ed by 7M HN03. Finally, he same p ocedu e, desc ibed
abo e o diges ed solid samples, is ollowed.
Fo he 226Ra analysis in sedimen samples, he 222Rn emana ion me hod
was used. The samples a e i s diges ed wi h HN03, aqua egia, HC104
and HF and hen he esidue is dissol ed wi h 8M HCl and he olume made
up o 0-51. The solu ion is hen ans e ed in o a sealed glass bo le and he
o iginal c op o 222Rn expelled by bubbling ul apu e He gas h ough. A e
app oxima ely h ee weeks secula equilib ium be ween a new c op o
222Rn and 226 Ra in solu ion is eached. The 222Rn is again expelled and
collec ed in a ZnOz-lined qua z coun ing cell. The 222Rn ac i i y is
measu ed by a gas scin illa ion coun e and om i he 226Ra concen a ion
in he sample is de e mined (I ano ich & Mu ay, 1992).
RESULTS AND DISCUSSION
As al eady s a ed, he indus ial zone unde s udy is si ua ed on a ongue o
land su ounded by he i e s Odiel and Tin o, wi h hei con luence a i s
ip (Fig. 2). The wo i e s a e a ec ed di e en ly by he indus ial ac i i y.
Consequen ly, he p esen a ion and he discussion o he esul s will be
ca ied ou sepa a ely o each i e . In he ables and igu es he au ho s
ha e deno ed wi h 'O' and 'SO' he wa e and sedimen samples,
espec i ely, om he Odie! i e . Simila ly, o he Tin o i e samples,
p e ix le e 'T' and 'ST' ha e been used. P e ix le e s 'OT' and 'SOT'
co espond o samples de i ed om he con luence o he wo i e s which
o ms a common mou h o he A lan ic Ocean. The numbe s gi en o each
sample iden i y he sampling s a ion (Fig. 2).
In addi ion o he U and Th iso opic ac i i ies exp essed in mBq/1 ( o
wa e samples) o mBq/g ( o sedimen samples), U and Th mass
concen a ions a e also gi en in µg/1 o µg/g. The wo a e ela ed by he
ollowing con e sion o mulae:
[U] = 0-08 l lA23s
[Th] = 0-2436A232
(1)
(2)
whe e [U] and [Th] a e he mass concen a ions and A238 and A232 a e he
ac i i ies o 238U and 232Th, espec i ely.
Odiel i e
The sampling s a ions a e dis ibu ed along he lowe eaches o he i e
close o he indus ial zone a ea (Fig. 2). The excep ion is s a ion 1 which is
si ua ed a ups eam o his a ea close o he i e sou ce.
Wa e
The U- and Th-iso ope ac i i ies a e gi en in Table 1 oge he wi h pH
alues. I is appa en ha all adionuclides measu ed in he collec ed wa e

TABLE 1
U- and Th-Iso ope Ac i i ies (m/Bq/1) and pH o Wa e Samples Taken Along he Odiel Ri e
238Th
Sample pH 23su 234u 232Th 230Th
01
3-01 197·9 ± 6·8 316-3 ± 10-7 13-4 ± 0-6 49.7 ± 1-7 22-9 ± 0-9
02 7-40 34-2 ± 1-1 36-3±1-2 0-58 ± 0-30 7-02 ± 1-33 2-65 ± 0-78
03 7-20 33·0 ± 2-0 35-0 ± 2-1 1-81 ± 0-14 12-0 ± 0-5 NM
NM
04 7-12 54·1 ± 3.4 58-7 ± 3.7 2-21 ± 0-24 14-3 ± 0-7
05 7-08 52·7 ± 3-6 54.3 ± 3.7 2-51 ± 0-25 18-9±1-3 7-52 ± 1-20
8-83 ± 2-89
2-38±0-15
06 6-80 131-3±11-3 136-2± 11-7 4.73 ± 0-67 34-2 ± 3.3
07 6-96 35-8 ± 0-9 39-2 ± 0-9 1-83±0-12 11-2±0-4
NM, No measu ed.
sample ollow he same dis ibu ion pa e n along he i e wi h wo well
de ined peaks.
The iso opic da a ob ained o sample O 1 a e anomalous ela i e o he
es o he da a se . The e y low pH alue o 3, due o local geology
condi ions, accoun s o he obse ed enhanced concen a ion lis ed. The
head wa e s o i e Odiel a e chemically agg essi e, esul ing in e ec i e
leaching and ans e o U and Th om he solid o he aqueous phase o
he sys em. The Th iso opes, mainly insoluble in na u al wa e s, ha e
concen a ions a leas one o de o magni ude highe han in a e age
su ace wa e s (Ma ínez-Agui e & Ga cía-León, 1992; Osmond &
l ano ich, 1992), e lec ing he highe mobili y o Th a e y low pH alues.
Highe concen a ions o U- and Th-iso opes also pe sis downs eam
be ween sampling s a ions 04 and 06, wi h a clea peak o ac i i y a
sampling s a ion 06. A simila pa e n was obse ed o U-iso opes in
samples collec ed in 1988 (Ma ínez-Agui e & Ga cía-León, 1991a). The
obse ed pa e n is indica i e o he exis ence o a local sou ce be ween
s a ions 04 and 06. The ob ious candida e o his local sou ce o
adioac i i y has o be ela ed o he phospha e manu ac u ing complex
loca ed be ween s a ions 04 and 05. The obse ed shi in he loca ion o
he peak o ac i i y om s a ions 05 and 06 in he wo sampling campaigns
is a esul o a lowe idal inpu and a highe ac i i y inpu (highe was e
ou pu om he phospha e ac o ies) o he i e a he ime o sampling.
This si ua ion was encoun e ed du ing he 1988 sampling campaign when
he ac i i y peak was obse ed highe ups eam a s a ion 05 (Ma ínez
Agui e & Ga cía-León, 1991a).
Table 2 p esen s he U and Th con en s o he wa e s collec ed in he
Odiel i e , and he co esponding Th/U mass a io oge he wi h he
234U /238U, 23ºTh/234U and 228
Th/232
Th ac i i y a ios. In Fig. 3, U and Th
concen a ions along he i e channel a e shown. The Th/U a ios ound
a e consis en wi h he well known ac o highe end o Th o be
associa ed wi h he solid phase in i e s. On he o he hand, such esul s a e
highe han no mally encoun e ed in mos i e wa e s (Osmond &
I ano ich, 1992) sampled ups eam om he es ua y. These esul s,
howe e , a e qui e simila o he mass a ios ob ained o he es ua ine
wa e s o he Guadalqui i i e (Ma ínez-Agui e, 1991; Ma ínez
Agui e & Ga cía-León, 1992).
The 234U/238U ac i i y a ios epo ed in Table 2 a e unusually low o
a i e sys em. A weigh ed a e age o he da a o s a ions 02 o 07 is
1-07 ± 0-02. This alue is mo e ypical o a p ima y mine al ac i i y a io
om a e ilize manu ac u ing p ocess han he a e age disequilib ium
obse ed in i e s (Sco , 1982).
Sample 01 is clea ly a di e en case. I s low pH p omo es he dissolu ion
TABLE 2
U and Th Concen a ions (µg/1), Th/U Mass Ra io and Iso opic Ac i i y Ra ios in Wa e Samples Taken Along he Odie! Ri e
Sample [U] [Th] Th/U 214u¡21su210Th/214U21sTh/212Th
01 ¡5.9 ± 0·6 3·31±0·15 0·208 ± 0·012 1·60 ± 0,02 0· 157 ± 0·008 1·70 ± 0·07
02 2.75 ± 0·09 0· 145 ± 0·075 0,053 ± 0·027 1,06 ± 0,03 0•71 ± 0-21 4-51 ± 2-49
03 2-68 ± 0-16 0-447 ± 0-035 0-167 ± 0,017 1-07 ± 0-02 0-34 ± 0-03
04 4.39 ± 0-30 0-546 ± 0-059 0,134 ± 0-017 1-08±0-10 0-24 ± 0-02
os 4·28 ± 0-29 0-620 ± 0-061 0-151 ± 0-018 1-02 ± 0-09 0-37 ± 0-04 3-00 ± 0-25
06 10-7 ± 0-9 ¡ .¡7 ± 0-16 0-110 ± 0-018 1-04 ± 0-04 0-25 ± 0-03 1-87 ± 0-67
07 2-88 ± 0-07 0-450 ± 0-029 0-157±0,011 1-10 ± 0-02 0-29 ± 0-01 1-31±0-11
(a)
ú)
úJ
02 03 04 05 06 07
(b)
-a-
o
J
�
� ··�
01 02 03 04 05 06 C1l OT1
Fig. 3. U concen a ion (a) and Th concen a ion (b) in µg/1 in wa e samples along he
Odie! i e .
o U-iso ope ac i i ies om he solid phase o he i e sys em. In such
condi ions, he 234 U-iso ope is p e e en ially mobilized, esul ing in 234U
en ichmen in he aqueous phase ela i e o 238U (Gascoyne, 1982) and
hence he highe 234U /238U ac i i y a io obse ed in sample O l.
The 23ºTh/234U ac i i y a ios epo ed in Table 2 a e anomalously high
when compa ed wi h o he i e sys ems. Thus, ypical ac i i y a ios o
i e wa e s a e a ound Ü· l o less (Pla e e al., 1992; Ma ínez-Agui e &
Ga cía-León, 1992). In he p esen case he weigh ed a e age 23ºTh/234 U
(a)
T1 T2 T3 T4 Ts Ts
(b)
ID
ú)
o -·� j
T1 " .2 T3 T4 Ts Ts OT1 OT2
Fig. 4. U concen a ion (a) and Th concen a ion (b) in µg/1 in wa e samples along he
Tin o i e .
The ma e ial discha ged a s a ions 2 and 4 mus also con ain U. The ac
ha enhanced le els o U ha e no been obse ed is p obably ela ed o he
di e en ial mobili ies o Th and U in aqueous sys ems. The U being much
mo e mobile han Th, i will end o edis ibu e mo e apidly in he mass o
wa e along he i e channel, esul ing in a smoo he dis ibu ion pa e n,
compa ed o Th which will be inco po a ed o he solid pa icles e y as .
The iso ope ac i i y a ios p esen ed in Table 6 o s a ions 2 and 4 may
help o suppo his p oposi ion.

TABLE 6
U and Th Concen a ions (µg/1), Th/U Mass Ra ios and Iso opic Ac i i y Ra ios in Wa e Samples Along he Tin o Ri e
234u¡2Jsu 230Th/234U22sTh/232Th 230Th/232Th
Sample [U} [Th} Th/U
TI 9-26 ± 0-32 4-82 ± 0-23 0-521 ± 0-031 1-83 ± 0-03 0-25 ± 0-01 3-60 ± 0-12 2-67 ± 0-09
T2 3-20±0-15 11-8±3,6 3-69±1·13 1-07 ± 0-04 2-14 ±0-64 0-27 ± 0-05 1-90±0-21
T3 3-82 ± 0-18 0-193 ± 0-028 0-050 ± 0-006 1-09 ± 0-04 0-11±0-01 1-27 ± 0-22 7-2 ± 0-8
T4 3-87±0-19 5.33 ± 1-21 1-38 ± 0-32 1-11 ± 0-04 0-77±0-17 0-10 ± 0-03 1-90 ± 0-21
T5 3-42 ± 0-08 0-136 ± 0-024 0-040 ± 0-007 1-08 ± 0-02 0-085 ± 0-007 7.1 ±0·3
T6 3-68±0-12 0-155 ± 0-015 0·042 ± 0-004 1-08 ± 0-03 0-077 ± 0-004 1-09 ± 0-17 6-0 ± 0-6
OT1 3.97 ± 0-11 0-135 ± 0-016 0-034 ± 0-004 1-09 ± 0-02 0-060 ± 0-004 0-91 ± 0·18 5.9 ± 0-7
OT2 2-80 ± 0-16 0-021 ± 0-008 0-008 ± 0-003 1-11 ± 0-05 0-016 ± 0-002 7.4 ± 2-8
The weigh a e age o he 234U /238U ac i i y a io o 1-09 ± 0-02
( excluding sample Tl) is s a is ically iden ical o he weigh ed a e age
ob ained o he Odiel i e wa e samples. The e o e, simila conclusions
can be d awn on he o igin o U-iso ope signa u es. Howe e , he impac o
he p esence o he phosphogypsum piles on he Tin o i e wa e s wi h
espec o U-iso opes is no as high as ha o he di ec inpu o phospha e
e ilize p ocess was es on he Odiel i e . In ac , i is e y di icul o
iden i y he sou ces o U ac i i ies om he da a p esen ed in Table 6. I
any hing, he only i m conclusion is ha any Th-en ichmen a s a ions 2
and 4 is apidly emo ed om he aqueous column and p esumably
adso bed on o he solid pa icles su ace. In ac , all o he Th/U mass a ios
a e ,.._, 10�2, in good ag eemen wi h published da a o o he i e sys ems
(Sco , 1982; Ma ínez-Agui e, 1991).
The 23ºTh/234U ac i i y a ios a e consis en wi h he abo e a gumen s,
adding weigh o he conclusion ha discha ge o he Tin o i e om he
phosphogypsum piles con ains a g ea <leal mo e Th han U. The dec ease
in he 228Th/232Th ac i i y a io a s a ions 2 and 4 in he Tin o i e e lec s
he ela i e immobili y o 228Ra, a p ecu so o 228Tb in he decay se ies, in
he phosphogypsum piles.
Sedimen
The iso ope adioac i i y in bo om sedimen s in he Tin o i e a e gi en in
Table 7. I compa ed o published U da a o bo om sedimen s in o he
i e sys ems (Sco , 1982; Descamps & Foulquie , 1988; Mo ón e al.,
1988; Pla e e al., 1992) i becomes clea ha he i e bo om sedimen s
i e accumula ing U and i s daugh e s. The concen a ions o 238U, 234U,
226Ra and 23ºTh a e lowe han hose epo ed in Table 3 o he Odiel i e
bu signi ican ly highe han he published le els o undis u bed i e
sys ems, always below 60 mBq/g o all o hem (Sco , 1982; Ma ínez
Agui e , 1991; Ma ínez-Agui e & Ga cía-León, 1992; Pla e e al., 1992).
This is no he case o 232Tb and i s daugh e 228Tb, whe e he
concen a ions a e simila o hose ound in he li e a u e o unpe u bed
sys ems, usually below 57 mBq/g o 232Tb (Sco , 1982; Ma ínez-Agui e,
1991; Ma ínez-Agui e & Ga cía-León, 1992).
Howe e , he ac ha all U-de i ed ac i i ies inc ease owa ds he
con luence wi h he Odiel i e may e lec a possible ans e o adioac i e
ma e ial om he Odiel i e o he Tin o i e . The ways h ough which
his occu s should be in es iga ed, bu mus be ela ed mainly o he idal
cycle and suspended ma e dynamics.
The co esponding ac i i y a ios o he Tin o i e bo om sedimen s
a e p esen ed in Table 8. Again, as in he case o he Odiel i e , he
weigh ed a e age 234U /238U ac i i y a io o 1-04 ± 0-03 sugges s an
Sample
-
STl
ST2
ST3
ST4
ST5
ST6
SOT1
ND, No de ec ed.
TABLE 7
U- and Th-Iso ope and 226Ra Ac i i ies (mBq/g) in Sedimen Samples Taken Along he Tin o Ri e
23su231u226Ra232Th230Th
15,7 ± 1-3 16·8 ± 0,8 25·2 ± 0-9 11,5±3·0 20-3 ± 4-0
195·2 ± 4-4 198-5 ± 4.5 146-0 ± 2-7 30·8 ± ¡.o 341,7±11·6
74.5 ± 2-8 80-9 ± 3.0 33.2 ± 0-5 45·0 ± 4.0 66·4 ± 5-2
133.1 ± 3,8 137,8 ± 3.9 49,6±1·1 36-1 ± 3·6 88-6 ± 6-6
342·0 ± 7.5 363·8 ± 7.9 46·1 ± ¡.o 25,3 ± 2·0 231-0 ± 12·3
516·9 ± 15-9 531-2± 16·3 149-9 ± 0-8 47.5 ± 4-0 490,8 ± 23·3
299-0 ± 12-6 304-5 ± 12-8 50-3±1·7 53-7±4·1 279·5 ± ¡5.¡
22sTh
ND
34.3 ± 1-5
48,9 ± 4-8
36-3 ± 4,1
30-8 ± 2·3
41·0 ± 4·0
55.4 ± 4.0
TABLE 8
U and Th Concen a ions (µg/g), Th/U Mass Ra io and Iso opic Ac i i y Ra ios in Sedimen Samples Along he Tin o Ri e
Sample [U][ThjTh/U
STI 1·26 ± 0·06 2·84 ± 0-74 2·24 ± 0.59
ST2 15·7 ± 0-5 7-6±0-3 0-485 ± 0·023
ST3 6-0 ±0·2 11-1 ± l·O 1·85±0·18
ST4 10-7 ± 0·3 3.9 ± 0-9 0·831 ± 0-087
ST5 27-5 ± 0·6 6-2 ± 0·5 0,226 ± 0,019
ST6 41-6±1·3 11,7 ± 1-0 0-282 ± 0·025
SOT1 24-0 ± l·O 13·2± l·O 0,550 ± 0-048
234U/23su 230Th/234U
1,07 ± 0-07 1-21±0·25
1.02 ± 0,02 1-72 ± 0·07
1·09 ± 0·05 0·82 ± 0-07
1·04 ± 0,03 0,64 ± 0·05
1-06 ± 0-02 0·64 ± 0·04
1·03 ± 0,02 0-92 ± 0·05
1-02 ± 0·03 0·92 ± 0·06
226
Ra/230Th
1-24 ± 0,25
0-43 ± 0·02
0·50 ± 0,04
0,56 ± 0,04
0,20 ± 0,01
0·31 ± 0·02
0·18±0,01
22sTh/232Th 230Th/232Th
1-77 ± 0-56
1·11 ± 0-05 11·1 ±0·5
1-09 ± 0-13 1-48
± 0· 15
1-01 ± 0,14 2-46 ± 0·26
1-22±0·10 9.2 ± 0·6
0,86 ± 0-10 10·3 ± 0·8
1-04 ± 0-09 5·2 ± 0·3
a i icial ongm o U-iso ope signa u es such as phosphogypsum piles
si ua ed along i s igh bank.
The gene al end in he iso opic a ios sugges a U-en ichmen in he
Tin o i e bo om sedimen s. Obse a ions made om he sedimen s in he
Odiel i e a e also alid o he Tin o i e case.
CONCLUSIONS
A ca e ul sampling campaign ca ied ou in 1989 o i e wa e and
bo om sedimen samples along he Odiel and Tin o i e s (sou hwes
Spain) has yielded comp ehensi e U, Th and 226Ra iso opic da a. These
da a ha e been in e p e ed o es ablish he connec ion be ween he
obse ed anomalously high concen a ions o U-, Th- and 226Ra-iso opes
in wa e s and sedimen s, and he ope a ions o phospha e e ilize ac o ies
loca ed in a zone i ually su ounded by bo h i e s. The conclusion based
on he iso opic da a is ha bo h liquid and solid was es a ising om he
e ilize p oduc ion, and discha ged om his indus ial zone, a e
esponsible o he obse ed adioac i i y enhancemen in he immedia e
en i onmen o he e ilize plan s.
ACKNOWLEDGEMENTS
The au ho s hank he Spanish DGICYT (con ac PB89-0621) and he
AMA o Jun a de Andalucía o he inancial suppo o his wo k. They
also wish o hank J. M. Ab il, G. Manjón and J. Díaz o helping in he
sampling, and a e obliged o Miss Sand a Hasle o Iso ope Geoscience
Sec ion, Ha well Labo a o y o in aluable help wi h he analy ical wo k.
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