.
..
1-
ANTHROPOGENIC EMISSIONS OF 21oPo, 21oPb ANO 226Ra IN AN
ESTUARINE ENVIRONMENT
A. MARTÍNEZ-AGUIRRE,* M. GARdA-LEÓN,* C. GASCÓ,** A. TRAVESI**
*Facul ad de Física, Uni e sidad de Se illa, 41080 Se illa (Spain)
**! ns i u o de Medio Ambien e, Ciema , 28040 Mad id (Spain)
An ex ensi e s udy on he dis ibu ion o na u al adionuclides in an es ua ine ecosys em loca ed in
Sou hwes em Spain is p esen ed. This en i onmen is highly a ec ed by he was es eleased by a
phospho ic acid indus y which uses phospha e ocks as aw ma e ial o e ilize p oduc ion. This ock
has gene ally high concen a ions o U and i s daugh e s. The es ua y is o med by wo i e s, Odiel
and Tin o, which ha e a common mou h in o he A lanic Ocean and a sal ma sh (Odiel ma sh) a ec ed
by he in come o Odiel i e wa e s. This i e ecei es di ec ly he liquid and pa o he solid (gypsum)
was es eleased om he indus ies. Besides ha , mos o he phosphogypsum was es a e s o ed in
unco e ed piles a he igh ma gin o he Tin o i e . The s udy has concluded ha he was es om
such indus ies a e he cause o he enhanced concen a ions ound a he bed o bo h i e channels as
well as he enhancemen ound in su ace soils in ce ain zones o he Odiel we ma shland. lndeed, he
No hem ma sh and he Moja e a channel a he Odiel ma sh seem o be he main sinks o he
con aminan eleased by he phospho ic acid indus y.
On a his o ical ime scale, sedimen s may be ega ded as, a leas , a empo a y sink
o much o he ma e ial which passes h ough he a ious chemical and biological
cycles ope a ing on he ea h's su ace. A p esen , he ma e ial which is eleased and
akes pa in hese cycles can ha e i s composi ion ma kedly a eé ed by an h opogenic
emissions. Sedimen s became an en i onmen al hos o many o he was e p oduc s
discha ged by socie y. Toe e ec s o hese man-made emissions, in so ne si ua ions, can
be su icien ly s ong o a ec highly he composi ion o he deposi ed sedimen .
In he ma ine en i onmen , nea -sho e sedimen s e ain he s onges memo y o he
impac o he eleased ma e ial on he ea h 's su ace. This is because hese sedimen s
accumula e a a es which can be as much as se e al o de s o magi ude highe han
hose in deep sea and because hey a e being o med in a eas in which many
an h opogenic subs ances ini ially each he sea. Mos indus ial complexes a e loca ed
in es ua ine a eas close o he sea. Thus, hey beha e as sinks o much o he
an h opogenic emissions, which wi h ime will p obably be anspo ed o hei close sea
en i onmen . Thus. he s udy o na u al en i onmen al adioac i i y in es ua ine sys ems
is o g ea impo ance and in e es in heal h physics and many o he pu poses.
J:;S. Pile• ol pho1phogypsum
O 3 km
Fig. l. Map o he Es ua ine a ea o Huel a. Bo om sedimen s om he Odiel and Tin o i e s a e deno ed
by "O" and "T', espec i ely, ollowed by a numbe which indica es he loca ion o he sample. Soil
samples om he Odiel ma sh a e deno ed by "M" ollowed by he numbe o he s a ion
In Spain a la ge indus ial complex is loca ed nea he ci y o Huel a, along he
es ua y o med by he Odiel and Tin o i e s. A phospho ic acid indus y o e ilize
p oduc ion is loca ed a he le ma gin o he Odiel i e (see Fig. 1 ).
Phospha e o es used o phospho ic acid p oduc ion con ain impo an amoun s o
na u al adioac i e elemen s, specially 238U and daugh e s, in concen a ions ha depend
on hei geog aphical and geological o igin, bu which can each up o 300 ppm o U.
Toe adioac i e impac o he indus ial complex o e he Odiel and Tin o i e s has
been widely s udied o he case o U and Th iso opes.1•2 A dose es ima ion due o he
222Rn inhala ion emi ed by he phosphogypsum piles has been also published.
3 Toe
mo emen s o hese wa e s due o he low o he wa e du ing change in ide, p oduce
he logical dis ibu ion o he con aminan upwa ds and downwa ds o he poin o
elease.
Nex o he i e s, he e is a la ge saline we ma shland. This a ea is a na u al
ese a ion wi h high biological ac i i y. I is loca ed a he igh side o he Odiel i e
in on o he e ilize indus y and is highly a ec ed by he income o he Odiel i e
wa e s. Toe adiological signi icance o 210Po, 210Pb and 226Ra in he u u e <lose
ecei ed by he popula ion mo i a ed he ex en ion o p e ious wo ks. Toe p esen pape
discusses he esul s ob ained in he s udy in he p esence o hese adionuclides in
bo om sedimen s om he Odiel and Tin o i e s as well as in su ace soil samples om
he we Ma shland. The gene al aim was o s udy he each and in luence ha he
e ilize p oduc ion has o e all he es ua ine a ea.
Expe imen al
Two sampling campaigns we e pe o med in Feb ua y and No embe 1993,
espec i ely. In each campaign bo om sedimen s om he Odiel and Tin o i e s and
su ace soil sampes om he Odiel Ma sh we e collec ed. Bo om sedimen s we e
collec ed a he cen e o he i e s, whe eas soil samples we e collec ed du ing he low
ide in a eas co e ed wi h wa e du ing he high ide.
Toe samples we e d ied, powde ed and homogenized be o e he analysis. So ne 1 g
o sample was spiked wi h well known 208Po ac i i ies. A e diges ion o he sample
wi h HN03 and aqua egia, Po is ex ac ed by sol en ex ac ion and he inal solu ion
is sel -deposi ed on o sil e planche s.4 210Po ac i i y is de e mined by a-spec ome y
wi h su ace ba ie o ion-implan ed de ec o s. 210Pb and 226Ra a e measu ed by
y-spec ome y wi h Re e se Coa ed Ge manium de ec o s. 210Pb duplica e analysis
we e pe o med in sedimen aliquo s,5•6 being signi ican ly conco dan wi h hose
ob ained by y-spec ome y.
Resul s and discussion
To simpli y he discussion, he da a ob ained on bo om sedimen s om he Odiel and
Tin o i e s o bo h sampling campaigns will be i s discussed. Fo he sake o cla i y,
we will deno e by "O" hose samples collec ed a he Odiel i e and by "T" hose om
he Tin o i e . Samples collec ed in he con luence o bo h i e will be deno ed by
"OT". The numbe ollowing hese da a will deno e he loca ion o he sampling s a ion
(see Fig. 1 ). La elly, da a ob ained o he same sampling campaigns in su ace soils
om he Odiel we ma shland will be p esen ed and discussed. Toe loca ion o he soils
collec ed a his a ea is shown in he same Figu e.
Code 210p0
01 518 ± 26
02 726± 21
03 4919± 126
04 1300± 100
05 884± 33
TI 76± 10
T2 221 ± 16
T3 1498±
75
OTl 474± 13
OT2 1062± 47
OT3 56± 5
OT4 54± 8
Bo om sedimen s
In Tables 1 and 2 he 210J>o, 210Pb and 226Ra ac i i y concen a ions in mBq/g
oge he wi h so ne ac i i y a ios, o Feb ua y and No embe campaigns a e p esen ed,
espec i ely.
F om he esul s o ali adionuclides in bo h sampling campaigns,7 i can be
concluded ha all bo om sedimen s om he Odiel i e p esen ac i i y concen a ions
Table 1
Radioac i e concen a ions in mBq/g in bo om sedimen s om he Odiel and Tin o i e s collec ed
in Feb uay 1993
210pb226Ra
506± 31 406± 96
922 ± 38 584± 88
2743 ± 64 3395 ± 198
1176 ± 41 1140 ± 129
763 ± 35 723 ± 65
31 ± 16 70± 20
82±20 �203
914 ± 40 618 ± 110
445 ± 27 211 ± 68
629 ±31 364± 77
20± 15 �67
<26 <62
Table 2
210p0¡210pb
1.02 ±0.08
0.79±0.04
1.79± 0.06
1.16 ± 0.07
2.45 ± 1.30
2.70±0.69
1.64 ± 0.11
1.07 ±0.07
1.69 ± 0.11
2.80±2.11
21 ºPb 226Ra
1.24± 0.30
1.57 ± 0.25
0.81 ±0.05
1.03± 0.12
1.05± 0.11
0.44± 0.26
1.47 ± 0.27
2.11 ± 0.69
1.73 ± 0.37
Radioac i e concen a ions in mBq/g in bo om sedimen s om he Odiel and Tin o i e s collec ed
Code 210p0
01 567 ± 38
02 500± 30
03 2080± 140
04 1330± 80
05 1660± 140
T1
T2 233± 16
T3 788± 50
OTI 600± 24
OT2 618± 39
OT3 21 ± 2
OT4 19 ± 2
in No embe 1993
210pb226R_a
511 ± 86 405 ± 55
419 ± 66 363 ± 75
925 ± 134 972 ± 109
1160 ± 189 831 ± 83
1450±213 1273 ± 112
98± 22 94± 22
73 ± 14 87± 20
733±116 718± 62
408 ± 70 407±
45
529 ± 81 416± 29
�35 �32
15± 10 19± 10
210p0¡210pb
1.11 ± 0.20
1.19 ± 0.20
2.25 ± 0.36
1.15 ± 0.20
1.15 ± 0.19
3.19 ± 0.65
1.08 ± 0.18
1.47 ± 0.26
1.17 ± 0.19
1.27 ± 0.86
21 ºPb 226Ra
1.26± 0.27
1.15 ± 0.30
0.95 ± 0.17
1.40± 0.27
1.14 ± 0.19
1.04 ± 0.34
0.84± 0.25
1.02 ± 0.18
1.00± 0.21
1.27
± 0.21
0.79± 0.67
...
abo e backg ound le els.
8 Thus, adioac i e concen a ions abo e 470, 445 and
211 mBq/g o 210Po, 210pb and 226Ra, espec i ely, a e ound along he es ua y o he
Odiel i e in Feb ua y. Radioac i e concen a ions in No embe a e simila o hos�
ound in Feb ua y. The highes ac i i y concen a ion is ound, as i was expec ed, a hc,
poin o elease o he phospho ic acid indus y (03), being he adioac i
concen a ion in Feb ua y much highe han ha in No embe o ali adionuclides. Tui
ac i i y concen a ion dec eases downs eam he i e channel bu s ill high adioac i d
concen a ions we e ound a he common con luence wi h he Tin o i e (OTl and
OT2). Pa em dis ibu ions o 210po and 210Pb along he Odiel i e o samples
collec ed in No embe a e shown in Fig. 2. These pa em dis ibu ions a e simila o
ha o 226Ra, and e lec s ali said abo e. Samples OT3 and OT4 we e collec ed a he
A lan ic Ocean coas close o he mou h o he i e . F om he da a in Tables 1 and 2
o s a ions OT3 and OT4 is easy o conclude ha he con amina ion in he Odiel i e
does no ye each he coas . In ac , adioac i e concen a ions a e simila o ypical
backg ound le els ( - 25 mBq/g).9
In he case o he Tin o i e channel, h ee samples we e collec ed. The adioac i e
concen a ion in bo h sampling campaigns a e simila and excep ing s a ion T3, hey a e
10l 5
CT
'b 4
x
3
2
_210Po
----- 210Pb
Fig. 2. Compa ison o 210Po and 210Pb ac i i y concen a ion in mBq/g in bo om sedimen s om he Odiel
i e collec ed in Feb ua y 1993
lowe han hose ound in he Odiel i e channel. The e o e, he excep ion o s a ion
T3, has an ac i i y concen a ion e en highe han in mos Joca ion o he Odiel i e�.
This s a ion is loca ed a he con luence o a small na u al i ule (Es e o del Rincón)
wi h he Tin o i e . This i ule c osses he phosphogypsum s o age a ea and p obably,

i can edissol e pa o he adioac i i y concen a ion con ained in hese was es.
S a ion T2 also seems o be con amina ed. This sample was collec ed close o an
a i ical s eam which c osses he phosphogypsum s o age a ea. Ups eam his s a ions,
he ac i i y concen a ions a e simila o backg ound.
F om he esul s i is clea ha he was es om he phospho ic acid p oduc ion
enhance he adioac i e concen a ions in bo om sedimen s om he Odiel and Tin o
i e s. Howe e , his con amina ion seems o be es ic ed o he es ua ine a ea o he
i e s, hus being he adioac i e concen a ions a he coas al a ea simila o
backg ound le els.
I is also in e es ing o discusse he 21°I>o/210Pb and 210Pb/226Ra ac i i y a ios which
a e also gi en in Tables 1 and 2 o Feb ua y and No embe campaigns, espec i ely.
The 21 0Po/21°I>b ac i i y a io e eals he exis ence o secula equilib ium in hose
s a ions less con amina ed whe eas hose highly enhanced show an excess o 21°I>o
compa ed o 21°I>b. The excess is con i med by he alues o his ac i i y a io in s a ions
03, T2 and T3. This excess should e lec ei he a highe p esence o 210Po in he was es
om he indus ies o a di e en en i onmen al beha iou a e he elease. Toe excess
disappea s downs eam he i e channel. The excess o 210Po ound a s a ion STl,
loca ed ups eam om he phosphogypsum piles in he Tin o i e , which seems o be
unenhanced by he indus ies, mus be ela ed wi h he highe 21°I>o associa ion wi h
solid pa icles.
In he case o he 21°I>b/226Ra ac i i y a io, mos s a ions p esen alues which
indica e he exis ence o secula equilib ium be ween bo h adionuclides o a li le
excess o 210Pb compa ed o 226Ra. Howe e , s a ion 03 om he Odiel i e and T1
om he Tin o i e , p esen a clea excess o 226Ra ela ed o 210Pb (mainly in samples
collec ed in Feb ua y) gi en 210Pb/226Ra ac i i y a ios clea ly below uni y. This
si ua ion should be explained in di e en ways o each sample. Sample 03, was
collec ed a he poin o discha ge om he phospho ic acid indus y in o he Odiel i e .
Thus, he excess o 226Ra should indica e he exis ence o a simila excess in he was es.
As i is well know, phosphogypsum (mainly CaS04) a e en iched in 226Ra compa ing
wi h o he adionuclides ( om he 238U decay se ies.10 The equilib ium is es o ed
downs eam he Odiel channel due o a highe associa ion o Pb11 o solid phases as well
as o he edissolu ion o 226Ra in saline wa e s.8,12
Toe case o s a ion T1 loca ed ups eam om he indus ies mus be ela ed o a
highe p esence o 226Ra in solu ion. Thus, due o he solubili y o his adionuclide in
na u al wa e s, eleases o was es wi h high concen a ion o 226Ra would p oduce a
gene al inc ease o 226Ra in solu ion in compa e wi h uncon amined i e s. This excess
o Ra would p oduce a highe con ain o 226Ra in bo om sedimen s in loca ions
upwa ds, compa ed o 21 0Po whk.h has been al eady inco po a ed o he sedimen s.
Sw ace soils
In Tables 3 and 4 adioac i e concen a ions o he same adionuclides and same
ac i i y a ios as hose o bo om sedimen s a e p esen ed he e bu o su ace soil
samples om he Odiel we ma shland. In each Table esul s o Feb ua y and
No embe campaigns a e p esen ed, espec i ely.
Toe esul s e eal clea ly ha he Ma sh is also enhanced by he phospho ic acid
p oduc ion.13 Toe ac i i y concen a ions a e, in gene al, below he maxima o�nd in
bo om sedimen s om he Odiel i e . Howe e , ac i i y concen a ions up o 370, 660
and 500 mBq/g o 210Po, 210J>b and 226Ra, espec i ely, we e ound in Feb ua y, being
in No embe he le els up o 580, 670 and 600 mBq/1 o 210Po, 210Pb and 226Ra,
espec i ely. Besides ha , much highe adioac i i y concen a ions we e ound in
samples collec ed in he No he n ma sh (see Fig. 1) in he campaign o No embe .
In he Odiel i e ma gin o he ma sh, eigh s a ions we e sampled o soils. These
loca ed in on o he e ilize indus ies, p esen adioac i e concen a ions in he
campaign o Feb ua y only sligh ly abo e backg ound concen a ions, being hose
ups eam and downs eam mo e con amina ed. In No embe , he s a ion in on o he
indus ies p esen s he lowes adioac i e concen a ions, below he concen a ions
ound in Feb ua y. Thus, i seems ha con amina ion in he ans e sal di ec ion is no
as high as in he longi udinal di ec ion. O cou se, his ac mus be ela ed wi h he low
eloci y o he i e wa e . Toe di e ences in s a ions M20 and M21 be ween bo h
Table 3
Radioac i e concen a ions in mB/g in su ace soil samples collec ed a he Odiel we ma shland
Code 2JOp0
M6 264 ± 412
M7 290± 31
MIO 341 ± 19
Mll 276± 14
M12 25.1 ± 1.7
M14 108±6
MIS 367 ± 34
M16 117±7
M20 288 ±25
M21 181 ± 14
M22 168±9
M23 124± 8
M24 44.9 ± 2.9
M18 29.0± 1.8
M17 40.5 ±2.3
in Feb ua y 1993
210pb 226Ra
454 ±27 321 ± 40
424 ±29 280± 43
514±36 326± 56
435 ±30 304± 39
37.4 ± 9.1 26.4 ± 14.8
160±25 143 ± 35
658 ± 30 505 ± 44
137 ± 18 65.4 ± 25.4
125 ±20 �241
125 ± 21 � 148
236 ±25 136 ± 36
205 ±23 76.6± 35.9
34.8 ±6.8 33.2 ± 11.4
34.0± 8.4 34.8 ± 13.7
53.2 ± 6.5 43.3 ± 10.5
2H)po¡2JC>pb
0.581 ± 0.043
0.684 ± 0.087
0.663 ± 0.059
0.634 ± 0.054
0.671 ± 0.169
0.675 ± 0.112
0.558 ± 0.058
0.854 ± 0.123
2.30 ±0.42
1.45 ± 0.27
0.716 ± 0.085
0.605 ± 0.078
1.29 ± 0.26
0.853± 0.217
0.761 ± 0.102
21 Opb¡226Ra
1.41 ± 0.20
1.51± 0.25
1.58±
0.29
1.43 ± 0.21
1.42± 0.87
1.12 ± 0.32
1.30± 0.13
2.10±0.86
1.73± 0.50
2.68 ± 1.29
1.05 ± 0.41
0.98± 0.45
1.13 ± 0.33
Table4
Radioac i e concen a ions in mBq/g in su ace soil samples collec ed a he Odiel we ma shland
in No embe 1993
Code 210p0 210pb226R_a210p0¡210pb210pb¡226Ra
Ml 199± 10 236± 16 166± 25 0.843 ± 0.071 1.42 ± 0.24
M2 778 ± 41 820±27 711 ± 45 0.949 ± 0.059 1.153 ± 0.082
M3 643 ±28 795 ±23 681 ± 36 0.811 ± 0.042 1.167 ± 0.070
M4 210± 11 233 ± 13 242 ± 23 0.901 ± 0.069 o. 963 ± 0.106
M5 222± 11 156 ± 14 161 ± 24 1.42 ± 0.15 0.97 ± 0.17
M6 580±26 673 ± 16 598 ±25 0.862 ± 0.044 1.125 ± 0.054
M7 213 ± 10 287 ± 12 213 ± 21 0.742 ± 0.047 1.347 ± 0.144
M8 130±7 212 ± 14 130± 21 0.613 ± 0.052 1.631 ± 0.285
M9 141 ±7 161 ± 12 149 ± 20 0.876 ± 0.078 1.081 ± 0.166
MIO 188 ± 10 161 ± 13 149 ± 22 1.168 ± 0.113 1.081± 0.182
Mll 64.6±4.0 76.2 ± 12.3 49.0± 18.6 0.848 ± 0.147 1.56 ± 0.64
M12 27.9 ± 2.0 24.8 ± 12.3 46.0± 22.3 1.13 ± 0.56 0.54 ± 0.37
M13 565 ±23 681 ± 23 673 ± 39 0.830 ± 0.044 1.012 ± 0.068
M14 41.0 ± 3.2 18.4 ± 10.1 30.4± 16.5 2.23 ± 1.24 0.605 ± 0.467
M15 441±20 589 ± 21 484± 32 0.749 ± 0.043 1.217±0.091
M16 131 ±7 162 ± 11 134 ± 16 0.809 ± 0.070 1.21 ±0.17
M19 233± 11 268 ± 15 245 ± 26 0.869 ± 0.064 1.094 ± 0.131
M20 16.2 ± 2.5 15.4± 10.1 21.3 ± 16.0 1.05 ±0.71 0.72 ±0.72
M21 37.2 ± 2.5 22.9 ± 10.9 20.3 ± 17.7 1.62 ±0.78 1.12 ± 1.12
M22 44.2±2.5 26.6 ± 11.1 31.7 ± 17.2 1.66 ±0.70 0.84 ±0.57
M23 194±9 121 ± 13 97.3 ± 20.7 1.61 ±0.19 1.24 ±0.30
M18 54.4± 3.7 51.9 ± 11.1 35.3 ± 17.6 0.830 ± 0.044 1.012 ± 0.068
M17 54.7 ± 3.7 51.9 ± 11.1 35.3 ± 17.6 0.68 ± 0.10 2.7 ± 1.7
campaigns mus be ela ed o he composi ion o he samples. Thus, samples collec ed
in No embe had highe con en o sand pa icles, which was e lec ed in he densi y
(0.7 and 1.5 g/cm3 d y weigh in Feb ua y and No embe , espec i ely), and in he
o ganic con en (10% and 1.5%, espec i ely) o he samples. Concen a ions a he eas
side o he Sal és island, which clea ly e eals a con amina ion, a e simila o hose
ound in bo om sedimen s a he con luence o he Odiel and Tin o i e s (OTl and
OT2). Toe di e ences ound in s a ions a he eas side o he Sal és island again mus
be pa ially ela ed wi h he composi ion o he samples. Thus, alues o densi y and
o ganic con en o s a ions M16 and M14 may e eal ha hey ha e a high amoun o
sandy pa icles, which p oduces a dec ease in he speci ic ac i i y o he samples.
In gene al, he di e ences i11 adioac i e concen a ions in s a ions along he Odiel
i e ma gin could be due o di e ences in o ganic con en . I we nonnalize he
adioac i e concen a ions o he o ganic con en o he soil samples, he di e ences
,,,,
be ween s a ions a e less signi ica i e. This e ec can be clea ly obse ed in Fig. 3,
whe e he 210Po concen a ion in mBq/g a e compa ed wi h he da a no malized o he
o ganic con en o hose soils along he Odiel i e ma gin, which showed wide
di e ences in composi ion. Only, s a ion M14 does no seem o be con amina ed in he
same deg ee as hose s a ions in he icini y.
300
200
100
M21 M20 M19 M13 M14 M15 M16
Fig. 3. Compa ison o 210Po ac i i y concen a ion in mBq/g o d y soil sample (con inuous line) wi h he
21 Üpo ac i i y concen a ion nonnalized o he o ganic con en o he soil samples (dashed line) collec ed
along he Odiel i e bank o he Odiel ma sh in No embe 1993. Da a o no malized concen a ions
(in mBq/g) ha e been di ided by 10
Besides, ha , a se o samples appea s in which he in luence o he was es eleased
om he indus ies is clea ly e lec ed. Thus, soils along he Moja e a channel ha e
qui e high adioac i e concen a ions. I we conside ha he cause o he high ac i i y
concen a ions ound in sedimen s O 1 and 02 was he mo emen o he con aminan s
ups eam he Odiel i e du ing high ide, his should be also he cause o he
con amina ion along he Moja e a channel. Thus, du ing he high ide he Odiel
i e wa e lows ups eam. Pa o his con amina ed wa e will low o he No hem
ma sh and he o he pa will lood he Odiel ma sh h ough he no h o he Bacu a
island. The same could occu h ough he sou h o his island. O his mos o he
con amina ed wa e lows in o he Moja e a channel and a small pa would low in o
he Cha e channel. The ac i i y concen a ion a he No hwes o he Enmedio island
dec eases downs eam hc Cha e channel and he Pun a Umb ía i e , whe e backg ound
concen a ions o 210Po. 210Pb and 226Ra we e ound. Thus, he pa em dis ibu ion o
adioac i i y concen a ions in soils ac oss he ma sh has clea ly iden i ied he way o