Deposition of fission product radionuclides in lichens and coniferous plants in Turkey

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<ul><li><p>Jointly published by Elsevier Science S. A., Lausanne and Akad~miai Kiad6, Budapest </p><p>J .Radioanal .Nucl . Chem.,Letters 200 (2) 147-158 (1995) </p><p>DEPOSITION OF FISSION PRODUCT RADIONUCLIDES IN LICHENS AND CONIFEROUS PLANTS IN TURKEY </p><p>H. Akgay </p><p>Department of Chemistry, Dokuz Eyl~l Univers i ty of Izmir, </p><p>TR-35150 Buca-Izmir, Turkey </p><p>Received 20 January 1995 Accepted 31 January 1995 </p><p>The effects of the Chernobyl disaster on l ichens and pines, which are widely distr ib- uted in northern and western Turkey, have been examined within the four years between 1986-1990. Analyses of the plants studied by y-spectrometry and spectrophotometr ic tech- niques have shown that the highest radio- active pol lut ion was observed in the Pseud- evernia furfuracea. The effects of Chernobyl on the ecosystem have been examined by com- paring di f ferent plant species from the point of view of their reception and accu- mulat ion of fal lout radionucl ides. </p><p>INTRODUCTION </p><p>The existence of radioact ive fal lout in plants has </p><p>recent ly become the center of special interest for en- </p><p>v i ronmental ists because of their part icu lar i ty in inter- </p><p>ception and retention of radioact ive isotopes, and studies </p><p>on the transfer of these elements to people through food chains1,9,12,14,15,18,19 </p><p>0236-5731/951US $ 9.50 Copyright 9 1995 Akad(rniai Kiad6,BlMapest All rights reserved </p><p>147 </p></li><li><p>AKCAY: DEPOSITION OF RADIONUCLIDES IN LICHENS </p><p>The data and f indings related to one of the major nu- </p><p>clear accidents in the history of nuclear energy, which </p><p>occurred in Chernobyl, Ukraine, are stil l considered to </p><p>be current issues with a great number Of indefinite as- </p><p>pects in the Ukraine and other countr ies in eastern </p><p>Europe. The major i ty of f ission product radionucl ides </p><p>re leased into the atmosphere as a result of this nu- </p><p>clear accident remained in the region near Chernobyl. </p><p>The main f ission product radionucl ides in Turkey and </p><p>other countries contaminated by the radioact ive pollu- </p><p>t ion were 131I, 137Cs and 134Cs. The radioact ive ele- </p><p>ments which reached Turkey via radioact ive clouds did </p><p>not remain for a long time over Turkey, so that the </p><p>doses of radiat ion through air did not cause s igni f icant </p><p>effects. </p><p>In the first days after the accident, the measure- </p><p>ments showed that 90% of the radioact iv i ty accumulated 131 </p><p>in the soil was I, and after the sixth and seventh </p><p>weeks it was proved that this amount decreased by half </p><p>for cesium and the other radioact ive elements. </p><p>It has been determined that the radioact ive pollu- </p><p>t ion varies by a factor of 10 over di f ferent localit ies, </p><p>depending on the radioact ive fallout. According to eco- </p><p>logical characterist ics, especia l ly l ichens and pine </p><p>trees are indicate most def initely the radioact ive pol- </p><p>lution. It was proved a long time ago that these plants </p><p>play an important role in the transfer of radioact ive </p><p>elements to people. </p><p>In this work, coniferous plants and l ichens which form </p><p>vast green areas especial ly in the northern and western </p><p>regions of Turkey, have been examined to determine the </p><p>level of contaminat ion from the Chernobyl accident. </p><p>148 </p></li><li><p>AK~AY: DEPOSITION OF RADIONUCLIDES IN LICHENS </p><p>"~' Jl </p><p>~'~C.,% " , . . . . . -x . JZ 9 </p></li><li><p>AKCAY: DEPOSITION OF RADIONUCLIDES IN LICHENS </p><p>species of the same kind of needle shoots of pine were </p><p>collected. </p><p>The samples were mi l led and dried for 8 h at 110 ~ </p><p>Consider ing the low boi l ing point of cesium, samples with </p><p>low act iv i t ies were turned into ash form at 500 ~ and </p><p>samples of 1.0-10.0 g taken from this ash were measured </p><p>by a planar X-ray detector. The detect ion l imit was re- </p><p>duced to 10 Bq by this detector. </p><p>Each sample dried and weighed was placed into a Mari- </p><p>nell i beaker or a transparent container of 125 ml and </p><p>was counted using a HPGe technique. </p><p>The y-spectra of the samples were taken at the Radio- </p><p>chemistry Laboratory of Nice University, and the Nuclear </p><p>Research Center of 9ekmece, Istanbul. The analyses were </p><p>made by using two di f ferent germanium detectors. The </p><p>first one was a coaxial HPGe detector (EG-G ORTEC) with </p><p>a re la t ive ef f ic iency of 17% and a resolut ion of 1.9 keV </p><p>(FWHM) at 1.33 MeV. The second one was a 2 ml planar de- </p><p>tector with a low energy photon spectrophotometer X-ray </p><p>detector. </p><p>RESULTS AND DISCUSSION </p><p>The radio isotopes and the act ivity values of the </p><p>l ichens col lected from the East and West Black Sea region </p><p>and from the Aegean region are shown in Table I. </p><p>The isotope values that have been measured in the vi- </p><p>cinity of Izmir show a concordance with the f indings </p><p>during studies in Southern France, South-Western Poland </p><p>and Austr ia (Table I). </p><p>On the hypothesis that act iv i t ies measured in Septem- </p><p>ber 1986 have decreased only due to radioact ive decay, </p><p>these act iv i t ies have been compared with the values meas- </p><p>150 </p></li><li><p>AK~AY: DEPOSIT ION OF RADIONUCL IDES IN L ICHENS </p><p>0 </p><p>T tm </p><p>.,-i </p><p>o </p><p>o </p><p>m </p><p>0 .,--I </p><p>c~ 1.4 </p><p>o .~ tl~ ol </p><p>o </p><p>o </p><p>2 </p><p>0 0 0 ~ 0 0 ~ 0 ~ 0 ~ ~ </p><p>0 0 0 ~ 0 0 ~ 0 ~ ~ 0 ~ </p><p>0 0 0 0 0 ~ ~ ~ 0 ~ 0 ~ </p><p>~ 0 ~ 0 </p><p>0 0 0 0 0 0 </p><p>0 ~ 0 ~ </p><p>9 9 o o </p><p>o </p><p>I.-i :J r~-,~ </p><p>~.~ ~ P </p><p>o~-~ o,--~ 9 ~-~ o </p><p>m ~o~Jm~ </p><p>0 0 0 0 N N N N ~ ~ - ~ . ~ </p><p>~ N N </p><p>kO oo 0"1 v - </p><p>~ 0 0 0 ~ 0 0 </p><p>~ 0 0 0 0 ~ </p><p>~ 0 0 ~ ~ </p><p>~ 0 ~ 0 0 ~ 0 ~ ~ 0 ~ 0 </p><p>~ ~ o ~ 1 ~ </p><p>~ 0 ~ 0 0 0 ~ 0 </p><p>~ 0 I ~ I O ~ I ~ I </p><p>9 9 o o </p><p>t~ t~q4 o ~ ~ </p><p>I~ ~-~ ~-~ 1~ o -~ </p><p>~ r ~ o ~ o c o o </p><p>0 0 0 0 0 </p><p>. ~ - ~ . ~ ~ </p><p>N N N ~ ~ </p><p>oo O~ v - </p><p>t t~ ! t 1 I v-- </p><p>o ~ </p><p>~ o ~ </p><p>~ 0 ~ ~ o ~ I </p><p>I I I I I I </p><p>cq e~ o I t~l I Lr~ I </p><p>w-- </p><p>0 0 I kD I U~ I I </p><p>9 9 o </p><p>..4 t~ </p><p>..IJ 4-t [,,..-I -,'-'1 }4,-4 0 0 ~ </p><p>4a ~104/ t~ ~ </p><p>0 0 0 0 0 0 N N N N m N </p><p>cO oO </p><p>~O I I ! ~ I </p><p>~ 0 ~ 0 ~ </p><p>~ 0 </p><p>I l l l l </p><p>0 i LO I Cq I </p><p>"0 I I I ~ I </p><p>a~ o o </p><p>. .~ ~ -,-.I ,.-.-t </p><p>-,4 I&gt;-~- ,~ ~ ,-~ O~ ~0 </p><p>0 0 0 0 0 N N N N N </p><p>135 </p><p>p- </p><p>I I I </p><p>CD I r',,1 </p><p>i I </p><p>qJ 0 </p><p>151 </p></li><li><p>AKCAY: DEPOSITION OF RADIONUCLIDES IN LICHENS </p><p>3ooo- {13,c, ~_ 2700 </p><p>2400 2100 </p><p>1800 </p><p>1500 - 13 </p><p>1200 ~~1~, 900 - Ce/144pr </p><p>600-'~ u%~ '06Ru I 106Rh </p><p>300-125Sb i ~ , ~ ~ ~ ~ 0 1 1986 1987 1988 1989 1990 </p><p>Year Fig. 2. Var ia t ion of ac t iv i ty for a l i chen co l lec ted </p><p>f rom Trabzon </p><p>,~ 2700 " '37cs~ </p><p>2400 </p><p>&lt; 2100 </p><p>1800 - </p><p>1500 </p><p>1200i- ~4C s 900 o </p><p>600 106Ru </p><p>300 q03Ru~~. .~ </p><p>198.6 1987 1988 1989 1990 Year </p><p>Fig. 3. Var ia t ion of ac t iv i ty for Parmel ia t rac t i ca col lected f rom Trabzon </p><p>152 </p></li><li><p>AKCAY: DEPOSITION OF RADIONUCLIDES IN LICHENS </p><p>ured in the subsequent years (Figs 2 and 3). The Am/A d </p><p>values for Lecanora mural is (A m act iv i ty measured and </p><p>A d act ivity calculated for decay) show a rapid in- </p><p>crease. </p><p>In the fol lowing year the 134Cs adsorbed by the </p><p>l ichens has rapidly increased due to erosion, other at- </p><p>mospher ic phenomena and due to wash-out by rain. However, </p><p>in the beginning of 1988, this fast decrease has compara- </p><p>t ively slowed down and in 1988-1990 it has become ap- </p><p>proximately stable. This conclusion shows a similar ity </p><p>with the result obtained for 137Cs. </p><p>On the other hand, the decrease in the amount of 106Ru </p><p>is approximately half of the decrease obtained for Cs. </p><p>This result shows that the absorpt ion mechanism of' Ru is </p><p>different. </p><p>Among the l ichen species which have been systemati- </p><p>cal ly studied, Parmel ia furfuracea exhibits the highest -I </p><p>act ivity (6727 Bq kg ) and Parmel ia tractica shows the -I lowest act ivity (3882 Bq kg ) due to the fact that </p><p>these plants general ly exist on the surface of rock </p><p>(epilithic lichens) and this s ituat ion is quite incon- </p><p>venient for isotope absorpt ion (Tables 2 and 3). The </p><p>fact that Parmel ia furfuracea contains approximately </p><p>twice as much activity in comparison with Parmel ia </p><p>tract ica can be related to two di f ferent reasons: the </p><p>first one is that Parmel ia furfuracea has a very porous </p><p>structure and the other one is that this part icular l ichen </p><p>lives on the branches of trees (epiphytic lichen) and </p><p>therefore absorbs quite a large amount of radioelements </p><p>found in rain. </p><p>The cesium activit ies measured in the pine species in </p><p>the areas of Trabzon, Zonguldak and Izmir studied since </p><p>1986, are shown in Table 4. It was found that, according </p><p>to analyses carr ied out in pine trees in Northern Italy, </p><p>153 </p></li><li><p>AK~AY: DEPOSITION OF RADIONUCLIDES IN LICHENS </p><p>TABLE 2 </p><p>The Am/A d values for Pseudevern ia fur furacea, Ao, act iv i t ies measured in September 1986; A m , act iv i t ies </p><p>measured in years fo l lowing 1986; A d, act iv i t ies ca lcu la ted accord ing to rad ioact ive decay </p><p>Isotope T, year X A (1986) o </p><p>~/% </p><p>1987 1989 1990 </p><p>103Ru 0.1078 6.4290 630 </p><p>106Ru 1.0082 0.6874 650 </p><p>125Sb 2.77 0.2502 </p><p>134Cs 30.1 0.023 </p><p>(180/327) (122/164) (20/42) 0.55 0.63 0.48 </p><p>1320 (310/941) (280/673) (153/344) 0.33 0.42 0.46 </p><p>144Ce 0.7803 0.8881 1000 (200/411) 0.49 </p><p>TABLE 3 </p><p>T ime dependent rad ioact ive concentrat ions , in Bq kg -I and act iv i ty rat ios of P. fu r furacea co l lec ted from </p><p>Trabzon (nd: non-detected) </p><p>Year 103Ru 106Ru/106Rh 125Sb 134Cs 137Cs 144Ce/144pr 235 U </p><p>1986 630 650 177 1320 2950 1000 nd </p><p>1987 195 250 32 370 1170 320 nd </p><p>1988 60 122 - 280 956 156 nd </p><p>1989 - 52 - 218 808 - - </p><p>1990 20 - 159 740 </p><p>154 </p></li><li><p>AK(2AY: DEPOSITION OF RADIONUCLIDES IN LICHENS </p><p>TABLE 4 </p><p>Cesium inventory in Bq kg -I according to local it ies and years </p><p>Year Local i ty Plants species 134Cs 137Cs </p><p>1986 Trabzon Pinus brutia 49 181 Izmir Pinus brutia 45 169 Trabzon Pinus nigra 52 186 Izmir Pinus nigra 44 167 Trabzon Picea or iental is 86 307 </p><p>1987 Trabzon Pinus brut ia 44 165 Izmir Pinus brutia 37 150 Trabzon Pinus nigra 46 171 Izmir Pinus nigra 34 150 Trabzon Picea or iental is 77 285 </p><p>1988 Trabzon Pinus nigra 38 153 Zonguldak Pinus nigra 7 32 Izmir Pinus nigra 25 94 Trabzon Picea or iental is 68 249 </p><p>1989 Zonguldak Pinus mar i t ima 4 12 </p><p>Middle France and Belgium, these show 4-6 times greater </p><p>pol lut ion than those in the Eastern Black Sea region of Turkey4,5, 15-17 </p><p>The act ivity ratios for di f ferent isotopes of the same </p><p>element greatly resemble the ratio of the 137Cs act iv i ty </p><p>of any isotope in di f ferent areas. When Table 5 is exam- </p><p>ined, it can easi ly be seen that the act iv ity ratios for </p><p>di f ferent isotopes of the same element strongly resemble </p><p>the ratio of the same isotopes to 134Cs. These values </p><p>also show a s imi lar i ty to Baldini 's f indings for pine 4 needles of Northern Italy </p><p>Exper imental results show that the species studied have </p><p>a high absorpt ion rate for 134Cs, 137Cs and 40K isotopes. </p><p>155 </p></li><li><p>AKCAY: DEPOSITION OF RADIONUCLIDES IN LICHENS </p><p>TABLE 5 </p><p>Act iv i ty ratios for di f ferent isotopes measured in l ichens and pines (nd: non-detected) </p><p>Lichen Pine Ratio . . . . . </p><p>Trabzon Izmir T rabzon Zonguldak Izmir area area area area area </p><p>137Cs/134Cs 3.2 3.3 3.7 3.7 3.6 </p><p>103Ru/106Ru 2.2 2.2 nd nd nd </p><p>141Ce/144Ce 2.4 2.4 nd nd nd </p><p>On the other hand, it was observed that the pine species </p><p>covering most of the area col lected a lot of Cs isotopes </p><p>especial ly in the year fol lowing the Chernobyl accident. </p><p>It has been found that although there are di f ferences </p><p>between lichen species, their 137Cs uptake capacity is </p><p>approximately 10 times larger than that of pine species. </p><p>The radioactive pol lut ion of pine trees by rain is most ly </p><p>caused by pine needles. </p><p>Measurements carr ied out in di f ferent periods show </p><p>that the cesium activity is found especial ly in parti- </p><p>cles with radii below a few micrometers I'7'17 </p><p>Lichens have the character ist ics of col lect ing dust, </p><p>aerosol particles, radioelements and most of the heavy </p><p>metals5, 6'13'15'20, due to the slow growth and the long </p><p>life span of these plants and the fact that the plant </p><p>surface area to biomass ratio is very small and that each </p><p>unit of the surface has a lot of stomata. </p><p>The capacity of the plants to col lect and deposit ra- </p><p>dioact ive isotopes depends on their morphological struc- </p><p>ture. The uptake of radioisotopes into the leaf mesophyl </p><p>and their t ransportat ion to the root of the plant by </p><p>156 </p></li><li><p>AK(~AY: DEPOSITION OF RADIONUCLIDES IN LICHENS </p><p>other organs of the tree is a complex phenomenon, which </p><p>is related to some physiological factors and to chemical </p><p>interactions between plant tissue and the radioisotopes. </p><p>The author expresses his thanks to the Turkish Scien- </p><p>tific and Technical Board, which supported the main pro- </p><p>ject financially (DEBgA~, 39) and to Dr. T. Kesercio~lu </p><p>(Dokuz Eyl01 University), Dr. Volker John (Pfalzmuseum </p><p>for Naturkunde Bad DHrkheim, Germany), Dr. Ulvi Zeybek </p><p>(Ege University), Adnan Erdag (Ege University) who helped </p><p>to identify the plants. </p><p>REFERENCES </p><p>1. H. Akgay, G. Ardisson, J. Radioanal. Nucl. Chem., Letters, 128 (1988) 273. </p><p>9 r v </p><p>2. H. Akgay, T. Kesercloglu, Tr. Doga, J. Eng. Environ. 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