Enviro nme ntal Manage me nt No ttingham Tre nt Unive rs ity, No ttingham, UK
F.B. Pyatt and D.D. Gilbe rts o n An Atlantic sho re line e c o syste m re c o ve ring fro m Che rno byl (? ) Gamma-radio ac tivity: Isle o f Barra, We ste rn Isle s, Sc o tland Enviro nme ntal Manage me nt and He alth
9 / 2 [1 9 9 8 ] 5 4 –5 9
Results and discussion
Intertidal sites
T h e r es u lt s a r e p r es en t ed in Ta bles I a n d II. Wh er e com p a r ison is p oss ible, t h es e d a t a p oin t clea r ly t o a n a lm os t u n iver s a l over a ll im p r ovem en t in t er m s of d ecr ea sin g ga m m a cou n t s in t h e or ga n ism s su r veyed in 1994, in com p a r is on w it h t h e s it u a t ion d et ect ed in 1989.
In m or e d et a il, lich en s a t t h e b a s e of m a n y food ch a in s h ave b een n ot ed by sever a l wor k -er s t o b e effect ive b ioa ccu m u la t or s of t h e p r od u ct s of a t om ic r a d ia t ion (H a n son , 1966; Woodw ell a n d Ga n n u t z, 1967), in clu d in g a p p r ecia ble q u a n t it ies of ga m m a r a d ia t ion (P ya t t , 1988a ). Su ch ob ser va t ion s w er e su p p or t ed by t h e su r vey s of N ilon t ova a n d Alek -sa s h en k o (1992) w h o exa m in ed r a d ioa ct iv it y levels in or ga n ism s clos e t o t h e a ct u a l Ch er -n oby l r ea ct or a -n d fou -n d e-n h a -n ced ga m m a r a d ioa ct iv it y va lu es. In Rom a n ia , Ba r t ok a n d Mocs y (1990) r e p or t ed t h a t t h e 137Cs con t en t s
of lich en s h a d in cr ea sed eigh t een -fold d u r in g t h e p er iod 1965 t o 1988. T h ese n ew H eb r id ea n d a t a s u p p or t t h ese ob s er va t ion s on t h e b ioa c-cu m u la t or y r ole of lich en s. T h e lich en s in t h e in t er t id a l zon e h ave eleva t ed ga m m a cou n t s (Ta ble 1). La r ge cou n t s, in t h es e s h or elin e zon es, w er e a lso d et ect ed in ot h er a u t ot r op h s – in clu d in g t h e a lga e Pelv etia ca n a licu la ta a n d Fu cu s v esicu losu s, q.v . E ven so, t h es e n ew d a t a in d ica t e t h a t t h er e h a s b een a sign ifi ca n t
im p r ovem en t in en v ir on m en t a l q u a lit y r efl ect ed by t h e d ecr ea sed ga m m a cou n t s in t h ese or ga n is m s. T h ese r ed u ct ion s m ay b e r ela t ed t o sever a l fa ct or s in clu d in g n ew gr ow t h of t h e t h a llu s, loss of old er p or t ion s of t h a llu s by a gen cies in clu d in g gr a zin g p r es-su r e, a n d t h e d ecay of r a d ion u clid es es-su ch a s
137Cs. T h e h igh es t va lu e for lich en s (5.2 c.p.s.)
w a s r ecor d ed fr om R a m a lin a siliqu osa w h ich p ossesses a fr u t icose (bu sh y ) t h a llu s. H en ce, t h e la r ge su r fa ce a r ea of t h is lich en h a d t h e p ot en t ia l t o t r a p gr ea t er q u a n t it ies of a ir -b or n e r a d ion u clid es em a n a t in g fr om t h e Ch er n oby l exp losion . On t h e ot h er h a n d , t h e cr u st ose lich en (L eca n ora a tra ), w h ich is m or e closely a d p r es sed t o t h e su b st r a t u m a n d is a lso m or e slow ly gr ow in g, p r od u ced low er cou n t s (3.8 c.p.s.). T h e foliose lich en X a n th o-r ia sp., w h ich is in t eo-r m ed ia t e in go-r ow t h foo-r m b et w een cr u st ose a n d fr u t icose lich en s in t h e ca p a cit y of it s la r ge su r fa ce a r ea t h a llu s t o in t er ce p t a ir b or n e p ollu t a n t s, a lso d isp layed in t er m ed ia t e ga m m a -r a d ioa ct iv it y cou n t s (4.8 c.p.s.). Over a ll, t h e ga m m a -r a d ioa ct iv it y cou n t s p r od u ced by lich en s h ave d ecr ea sed by a p p r oxim a t ely 30 p er cen t b et w een 1989 a n d 1994.
Va r iou s p r op er t ies in t h e ga m m a -r a d ioa c-t iv ic-t y cou n c-t s n oc-t ed fr om lich en s in c-t h e 1989 su r vey h ave con t in u ed t o b e ev id en ced in 1994, for exa m p le, t h e m icr ogeogr a p h ica l r ela t ed va r ia b ilit y in t h e cou n t s fr om t h e cr u st ose lich en Ver ru ca r ia m a u ra . A We ste rn
Isle s
Be nbe c ula
Skye
So uth Uist
BARRA
Po rt Cao l
Mingulay
We ste rn Isle s
Sc o tland
Wale s
Che rno byl No
rw ay
BARRA
*
* * * *
*
0 km 3 0
Note: * o the r s ampling s ite s in So uth Uis t, Be nbe c ula, Skye , No rth Wale s , and No rway that are me ntio ne d in the te xt.
Figure 1
F.B. Pyatt and D.D. Gilbe rts o n An Atlantic sho re line e c o syste m re c o ve ring fro m Che rno byl (? ) Gamma-radio ac tivity: Isle o f Barra, We ste rn Isle s, Sc o tland Enviro nme ntal Manage me nt and He alth
9 / 2 [1 9 9 8 ] 5 4 –5 9
d ecr ea sed cou n t w a s a ga in n ot ed in t h a lli on t h e low er p a r t s of t h e in t er t id a l zon e (3.2 c.p.s.) com p a r ed t o t h ose t h a lli exp os ed on h igh er s h or elin e s it es (4.5 c.p.s.). T h e t h a lli loca t ed low er on t h e sh or e, a p p ea r, by v ir t u e of t h eir m or e fr eq u en t in u n d a t ion by t h e s ea , t o h ave b een r ela t ively p r ot ect ed fr om t h e Ch er n oby l r a d ion u clid es d u r in g t h e 1986 p r ecip it a t ion .
T h e ga m m a -r a d ioa ct iv it y cou n t s ob t a in ed fr om t h e b r ow n a lga e list ed in Ta ble 1 a lso illu s t r a t e a r ecover y w it h a m a r k ed d im in u -t ion in ga m m a va lu es. T h e r es u l-t s ob -t a in ed fr om Fu cu s v esicu losu s a n d Pelv etia ca n a licu -la ta r em a in com p a r a t ively h igh , bu t on ly in
t h ose t h a lli w h ich w er e a n ch or ed in r ock cr ev ices loca t ed h igh er on t h e s h or e. A p ossi-ble exp la n a t ion is t h a t t h e Ch er n oby l-p ol-lu t ed r a in m igh t h ave b ecom e p r efer en t ia lly con cen t r a t ed a n d t r a p p ed a ga in st t h e a lga l t h a lli in t h ese cr ev ices for a sign ifi ca n t p a r t of t h e t id a l cycle.
It ca n n ot b e p r oved in t h is fi eld st u dy t h a t a ll t h e r a d ioa ct iv it y d et ect ed in t h is su r vey h a s r esu lt ed fr om t h e Ch er n oby l exp losion ; ot h er sou r ces m ay h ave a lso con t r ibu t ed t o t h e ga m m a -cou n t s r ecor d ed . H ow ever, t h e ga m m a -r a d ioa ct iv it y va lu es of t h e d ee p er w a t er a lga e (e.g. L a m in a r ia ) a n d low er sh or e lich en s (e.g Ver ru ca r ia m a u ra ) a r e of Table I
Gamma-radio ac tivity c o unts fro m Po rt Cao l, Bo rve He adland, Is le o f Barra, We s te rn Is le s o f Sc o tland
cps cps cps cps
Intertidal zone 1989 1994 M achair – terrestrial zone 1989 1994
Biological producers Biological producers
Lichens Ammophila arenaria 2 .6 1 .2
Caloplaca marina 6 .6 4 .3 Ammophila arenaria (young root) – 1 .4
Lecanora atra 7 .1 3 .8 Ammophila arenaria (old root and bases) – 3 .3
Ochrolechia parella 6 .8 4 .2 Ameria maritima 3 .1 2 .0
Ramalina siliquosa 7 .1 5 .2 Argrostis/ Festuca spp. 2 .2 1 .5
Verrucaria maura (lower shore) 4 .8 3 .2 Bellis perennis 2 .4 1 .3
Verrucaria maura (exposed upper shore) 7 .9 4 .5 Brachythecium spp. 4 .1 2 .3
Xanthoria spp. 9 .2 4 .8 Peltigera spp. 4 .6 3 .0
Green algae Biological consumers
Enteromorpha intestinalis (growing on peat) 3 .1 1 .5 Sheep wool 3 .2 1 .8
Entermorpha intestinalis (on middle shore) 3 .0 2 .2 Sheep scapula 8 .6 3 .9
Brown algae Sheep scapula and skull – 4 .1
Ascophyllum nodosum 4 .3 3 .7 Lamb scapula and vertebrae – 1 .8
Fucus serratus 5 .3 4 .1 Sheep faeces 3 .4 2 .1
Fucus spiralis 5 .6 2 .9 Cattle faeces 2 .9 5 .0
Fucus vesiculosus 4 .1 2 .7
Fucus vesiculosus (in crevices) 2 0 .0 6 .5
Laminaria spp. 4 .9 1 .9
Pelvetia canaliculata 5 .4 3 .3
Pelvetia canaliculata (high on shore in crevices) 9 .6 6 .8
Red algae
Gigartina stellata 6 .9 2 .2
Porphyra umbilicalus 4 .9 2 .2
Biological consumers
Actinia equina 8 .1 4 .0
Balanus balanoides 5 .7 3 .7
Patella intermedia 4 .4 4 .3
Patella vulgata (tissue) 6 .8 3 .0
Patella vulgata (shell) 4 .6 4 .9
Sediment types
Exposed in upper part of intertidal zone
Surface of c. 4000 year old peat 2 .1 1 .5
Peat at 12 cms depth 0 .6 0 .6
M odern intertidal shell sand splash zone 1 .6 1 .6
F.B. Pyatt and D.D. Gilbe rts o n An Atlantic sho re line e c o syste m re c o ve ring fro m Che rno byl (? ) Gamma-radio ac tivity: Isle o f Barra, We ste rn Isle s, Sc o tland Enviro nme ntal Manage me nt and He alth
9 / 2 [1 9 9 8 ] 5 4 –5 9
p a r t icu la r in t er es t in t h is con t ext . T h e d a t a sh ow n in Ta ble 1 d em on s t r a t es t h a t t h ese or ga n ism s, w h ich wou ld h ave b een b ot h t h e m os t p r ot ect ed fr om Ch er n oby l fa llou t a n d a r e a ls o t h e m os t exp os ed t o p os sible s eaw a -t er -b or n e r a d ion u clid e con -t a m in a -t ion , h a d ver y low ga m m a -cou n t s.
T h e r ela t ive in t en sit ies of con t a m in a t ion a n d t h e over a ll p a t t er n of ga m m a -cou n t s for t h e con s u m er s in t h e in t er t id a l h a b it a t ob ser ved in 1989 h a s a ls o con t in u ed t o 1994, bu t a ga in t h er e h a s b een a n over a ll r ed u ct ion in t h e cou n t s. H et er ot r op h s a r e s h ow n t o p os s es s n ot a bly h igh er cou n t s t h a n t h e a u t ot r op h s t h ey con su m e. T h e r a n ge of cou n t s in h igh er t r op h ic levels ob ser ved h a s a lso con t in u ed . T h e d a t a ob t a in ed fr om s p eci-m en s of t h e in t er t id a l lieci-m p et Pa tella v u lga ta in d ica t e t h a t t h er e is a loca lis ed en h a n ce-m en t of r a d ioa ct ive p r od u ct s w it h in t h e s h ell m a t r ix, a s op p osed t o t h e soft t iss u es. Over a ll, t h es e d a t a m a t ch t h ose fr om a b r oa d ly s im ila r sit e in a n in t er t id a l a r ea in N or t h Wa les w h ich d isp lay s s im ila r p a t t er n s of a ccu m u la t ion t h r ou gh t r op h ic levels (P ya t t a n d Bea u -m on t , 1990).
Th e r a ised Ievels of ga m m a -r a dioa ctivity in th e h eter otr oph s com pa r ed to a u totr oph s h ave been expla in ed in t er m s of bioa ccu m u la t ion
t h r ou gh t r op h ic levels by P ya t t (1988b ) a n d P ya t t a n d Bea u m on t (1989, 1990, 1992, 1993).
A com p a r ison of t h e ga m m a -cou n t s fr om t h e su r fa ce a n d n ea r su r fa ce of a fou r t h ou -sa n d yea r old fr esh w a t er p ea t exp osed in t h e in t er t id a l zon e su ggest s a r ela t ively low level of con t a m in a t ion by r a d ion u clid es. T h er e a p p ea r s t o h ave b een lim it ed in fi lt r a t ion of r a d ion u clid es t o d e p t h . T h e r ed u ct ion in su r fa ce levels a r e p r esu m a bly b ein g a ch ieved by d a ily w a sh in g d u r in g t h e t id a l cycle. T h e ga m m a cou n t s fr om sh ell sa n d in t h e sp la sh zon e a p p ea r n ot t o h ave ch a n ged d u r in g t h e st u dy p er iod . T h ey a r e, h ow ever, n ot a bly low er t h a n t h e ga m m a cou n t s p r od u ced by t h e sh ell of live lim p et s. T h e a n t iq u it y a n d or igin s of s h ell s a n d in t h es e a r ea s is u n k n ow n .
M achair sites
T h e m a ch a ir a t t h is sit e is gr a zed by sh ee p a n d ca t t le a n d m ay b e over t op p ed by t h e sea a t t h e t im es of t h e h igh est st or m s. T h e loca l ve get a tion is t ypica l of loca l m a ch a ir (Gilber t -son a n d Ken t in (pr ess); P ya tt a n d Bea u m on t, 1989) a n d in clu ded A m m oph ila a ren a r ia , A r m er ia m a r itim a , Festu ca ru b ra , Festu ca ov in a , A grostis ten u is, B ellis peren n is, Pla n -ta go spp., L eon tod on spp., Hiera ciu m spp., Collem a spp., Cla d on ia spp., Peltigera spp., a n d B ra ch yth eciu m spp. Th e ga m m a -cou n ts for th is h a bita t a r e sh ow n in Ta bles I a n d II. T h er e is clea r eviden ce of a r edu ction in cou n ts fr om 1989 to 1994. In A m m oph ila a ren a r ia th e ga m m a -cou n ts h a d decr ea sed fr om 2.6 c.p.s. in 1989 to 1.2 c.p.s in 1994; h en ce r ecover y is a ppa r en t w ith th e developm en t of n ew folia ge. Th e h igh er va lu e of 3.3 c.p.s. obta in ed fr om th e old r oot a n d sh oot ba ses of A m m oph ila pr oba -bly r efl ects pr ocesses of tr a n sloca tion of r a dion u clides to older tissu e a n d a n a ctive a ccu m u la tion in th e older r oots. Th e oth er com pa r a tively h igh va lu e wh ich occu r r ed in th e lich en Peltiger a (3.0 c.p.s. in 1994) a ga in in dica tes th e well-developed a bility of som e lich en s to bioa ccu m u la te pollu ta n ts.
T h e a ccu m u la t ion of ga m m a -r a d ioa ct iv it y in t h e va r iou s t issu es of sh ee p a n d ca t t le w a s w ell d efi n ed in 1989 (Ta ble I). At t h a t t im e t h e r esu lt s for r ecen t ly d ea d sh ee p w er e – sca p u la 8.6 c.p.s. a n d fa eces 3.4 c.p.s. T h ese sh ee p sca p u la d a t a w er e n ot a b ly low er t h a n t h ose ob t a in ed by P ya t t (1988b ) on e yea r ea r lier, fu r t h er n or t h in t h e West er n Isles on t h e isla n d s of Ben b ecu la a n d Sou t h Uist (F igu r e 1), a n d a ll t h ese d a t a a r e m a r k ed ly low er t h a n t h e r ea d in gs ob t a in ed in West er n N or w ay, on ly 15 m on t h s a ft er t h e Ch er n oby l exp losion (P ya t t , 1988a ). T h e 1994 d a t a p r esen t ed h er e p oin t t o a r ecover y. It is h en ce a p p a r en t t h a t t h e h er b ivor es a r e st ill losin g r a d ion u clid es t h r ou gh t h eir fa eces. T h is ou t com e is lik ely t o Table II
Gamma-radio ac tivity c o unts fro m a fre s hly e xpo s e d fac e in mac hair s ands
cps cps
1989 1994
Ammophila arenaria 2 .6 1 .2
General machair vegetation 1 .5 –
Sand
0-5 2 .4 1 .3
5-10 2 .3 1 .4
10-15 2 .2 1 .5
15-20 2 .1 1 .6
20-25 2 .2 1 .7
25-30 2 .1 2 .0
30-35 2 .1 2 .2
35-40 2 .0 2 .3
40-45 – 2 .2
45-50 – 2 .1
50-55 – 1 .5
55-60 – 1 .4
60-65 – 1 .3
65-70 – 1 .3
70-75 – 1 .4
75-80 – 1 .2
80-85 – 1 .3
F.B. Pyatt and D.D. Gilbe rts o n An Atlantic sho re line e c o syste m re c o ve ring fro m Che rno byl (? ) Gamma-radio ac tivity: Isle o f Barra, We ste rn Isle s, Sc o tland Enviro nme ntal Manage me nt and He alth
9 / 2 [1 9 9 8 ] 5 4 –5 9
con t in u e. T h e b ody bu r d en w ill d ecr ea se a s a r esu lt of t h is p r ocess a n d a ls o a s t h e q u a n t it y of r a d ion u clid es in gest ed w it h food d eclin es t h r ou gh t im e. T h e r ela t ively h igh va lu es in t h e b on es in d ica t es t h a t 1oca lis ed a ccu m u la -t ion h a s occu r r ed in -t h e sk ele-t a l s y s -t em of t h es e h er b ivor es.
Th e m ovem en t of r a dion u clides th r ou gh th e m ediu m -coa r se, well-sor ted, ca lca r eou s sa n dy soils of th e ter r estr ia l sa n dy m a ch a ir a r e in di-ca ted in Ta ble II. Th er e is clea r eviden ce of a dow n w a r d m ovem en t th r ou gh th e m a ch a ir in th e pea k ga m m a r a dioa ctivity r ea din gs, a pr ocess fa cilita ted by th e h igh por osity of th ese sa n ds. In 1989, th e h igh est cou n ts w er e detected in th e u pper pa r t of th e pr ofi le. Th e over a ll pa tter n fou n d w a s sim ila r to th a t obser ved by P ya tt (1988a ) in podsols in u pla n d Wester n N or w ay, wh er e a m a r k ed r edu ction in ga m m a -cou n ts w ith in cr ea sin g depth w a s fou n d. By 1994 on Ba r r a , th e pa tter n h a s clea r ly ch a n ged. Th e cou n ts h ave dim in ish ed in m a gn itu de, a n d th e pea k va lu es h ave m igr a ted dow n w a r ds to a depth of 30-50 cm s.
Conclusions
It is a p p a r en t fr om t h is in ves t iga t ion t h a t d u r in g t h e fi ve-yea r p er iod fr om 1989 t o 1994 t h e ga m m a cou n t s h ave d im in is h ed in b ot h t h e h et er ot r op h s a n d a u t ot r op h s in a n in t er -t id a l/ s h or elin e s i-t e on -t h e w es -t er n coa s-t of t h e Is le of Ba r r a , Wes t er n Is les. Recover y is p r oceed in g a s a r esu lt of t h e gr ow t h of fr es h ve get a t ion , excr et ion by h er b ivor es of in gest ed r a d ion u clid es, t h e d ow n w a r d m ove-m en t of p ollu t a n t s fr oove-m t h e p ed osp h er e, a n d t h e d ecay of 137Cs. Lich en s a r e a ga in in d
ica t ed t o h ave b een im p or t a n t b ioa ccu m u la t or s of ga m m a r a d ioa ct iv it y a n d a ccu m u la -t ion -t h r ou gh -t r op h ic levels -t o h er b ivor es (e.g. sh ee p ) is a p p a r en t . T h r ou gh t im e, s h ee p a n d ca t t le a p p ea r t o b e in ges t in g a d im in is h in g loa d of p ollu t a n t s. T h ese n ew d a t a in d ica t e b ot h a n a ccu m u la t ion in t h e s k elet a l s y s t em , a n d t h e los s of r a d ion u clid es in fa eces. T h e va lu es in t h e la m b s ca p u la a t 1.8 c.p.s., a s com p a r ed w it h t h e sh ee p s ca p u la (3.9 c.p.s.) fu r t h er in d ica t e t h a t a n im p r ovem en t is occu r r in g. A clea r im p r ovem en t in en v ir on -m en t a l q u a lit y, over t h e p er iod 1989-1994, is su gges t ed by t h is st u dy.
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