{"id":4989,"date":"2018-08-10T08:31:07","date_gmt":"2018-08-10T07:31:07","guid":{"rendered":"https:\/\/www.vtei.cz\/?p=4989"},"modified":"2024-07-16T14:32:17","modified_gmt":"2024-07-16T13:32:17","slug":"determination-of-low-level-tritium-concentrations-for-tritium-tracing-applications","status":"publish","type":"post","link":"https:\/\/www.vtei.cz\/en\/2018\/08\/determination-of-low-level-tritium-concentrations-for-tritium-tracing-applications\/","title":{"rendered":"Determination of low level tritium concentrations for tritium tracing applications"},"content":{"rendered":"

<\/i> This article is available in Czech only. For translation or more information on this topic, please contact author.<\/h4>\n

 <\/p>\n

Souhrn<\/h2>\n

V\u00a0sou\u010dasnosti jsou hlavn\u00edmi zdroji tritia v\u00a0\u017eivotn\u00edm prost\u0159ed\u00ed p\u0159etrv\u00e1vaj\u00edc\u00ed dopady atmosf\u00e9rick\u00fdch test\u016f jadern\u00fdch zbran\u00ed v\u00a0minul\u00e9m stolet\u00ed, tritium vypou\u0161t\u011bn\u00e9 jadern\u00fdmi za\u0159\u00edzen\u00edmi a\u00a0jeho p\u0159irozen\u00e1 produkce v\u00a0atmosf\u00e9\u0159e. D\u00edky jeho v\u0161eobecn\u00e9 p\u0159\u00edtomnosti a\u00a0p\u0159\u00edzniv\u00fdm vlastnostem je tritium ve form\u011b HTO vyu\u017e\u00edv\u00e1no jako stopova\u010d v\u00a0podzemn\u00edch a\u00a0povrchov\u00fdch vod\u00e1ch. Od ukon\u010den\u00ed atmosf\u00e9rick\u00fdch jadern\u00fdch test\u016f obsah tritia ve sr\u00e1\u017ek\u00e1ch kles\u00e1 a\u00a0postupn\u011b se bl\u00ed\u017e\u00ed p\u0159irozen\u00fdm koncentrac\u00edm pod 1 Bq\/l. V\u00a0t\u00e9to souvislosti je t\u0159eba citliv\u00e9 metody stanoven\u00ed. \u010cl\u00e1nek popisuje v\u00fdvoj objemov\u00e9 aktivity tritia v\u00a0povod\u00ed Labe v\u00a0lokalit\u00e1ch bez p\u0159\u00edm\u00e9ho vlivu antropogenn\u00edch emis\u00ed tritia v\u00a0obdob\u00ed 2001\u20132017. Vyhodnocen\u00e9 \u00farovn\u011b jsou v\u00fdchoz\u00edm podkladem pro vyu\u017eit\u00ed tritia jako stopova\u010de, nap\u0159. v\u00a0oblasti hydrogeologick\u00e9ho modelov\u00e1n\u00ed.<\/p>\n\"\"<\/a>\n

\u00davod<\/h2>\n

Tritium (3<\/sup>H) je radioaktivn\u00ed izotop vod\u00edku s\u00a0polo\u010dasem p\u0159em\u011bny 12,32 r, resp. 4\u00a0500\u00a0\u00b1 8 d [1], kter\u00fd se p\u0159irozen\u011b vyskytuje v\u00a0mno\u017estv\u00ed 1 atom na 1018<\/sup> atom\u016f vod\u00edku. Tritium p\u0159irozen\u011b vznik\u00e1 jadern\u00fdmi reakcemi vyvolan\u00fdmi kosmick\u00fdm z\u00e1\u0159en\u00edm v\u00a0horn\u00edch vrstv\u00e1ch atmosf\u00e9ry, pat\u0159\u00ed mezi tzv. kosmogenn\u00ed radionuklidy\u00a0[2]. Ro\u010dn\u00ed kosmogenn\u00ed produkce tritia je odhadov\u00e1na na 72 PBq\/r (72\u22191015<\/sup>\u00a0Bq), co\u017e odpov\u00edd\u00e1 p\u0159irozen\u00e9mu konstantn\u00edmu v\u00fdskytu tritia v\u00a0atmosf\u00e9\u0159e p\u0159ibli\u017en\u011b 1 275\u00a0PBq [3]. P\u0159irozen\u00e1 \u00farove\u0148 tritia ve sr\u00e1\u017ek\u00e1ch v\u00a0oblasti st\u0159edn\u00ed Evropy je odhadov\u00e1na na 5 TU [4]. Tritiov\u00e9 jednotky (TU) jsou odvozeny z\u00a0p\u0159irozen\u00e9 koncentrace tritia. Pro p\u0159evod hodnot uveden\u00fdch v\u00a0TU plat\u00ed vztah 1 TU = 0,11919 \u00b1 0,00021 Bq\/kg [5]; 5 TU je tedy p\u0159ibli\u017en\u011b 0,6 Bq\/l. Hansl\u00edk [6] na z\u00e1klad\u011b d\u0159\u00edv\u011bj\u0161\u00edch odhad\u016f uv\u00e1d\u00ed pro p\u0159irozenou \u00farove\u0148 tritia ve sr\u00e1\u017ek\u00e1ch hodnotu 0,38 Bq\/l.<\/p>\n

Um\u011ble je produkov\u00e1no tritium zejm\u00e9na v\u00a0d\u016fsledku vyu\u017e\u00edv\u00e1n\u00ed jadern\u00e9 energie a\u0165 u\u017e pro m\u00edrov\u00e9, nebo vojensk\u00e9 \u00fa\u010dely. V\u00a0jadern\u00e9m reaktoru vznik\u00e1 tritium p\u0159i \u0161t\u011bpn\u00fdch procesech (tern\u00e1rn\u00ed \u0161t\u011bpen\u00ed) a\u00a0aktiva\u010dn\u00edch procesech v\u00a0konstruk\u010dn\u00edch materi\u00e1lech, chladivu a\u00a0moder\u00e1toru. Doposud nejv\u011bt\u0161\u00edm zdrojem tritia v\u00a0atmosf\u00e9\u0159e, kter\u00fd je st\u00e1le m\u011b\u0159iteln\u00fd, v\u0161ak byly testy jadern\u00fdch zbran\u00ed v\u00a0pades\u00e1t\u00fdch a\u00a0\u0161edes\u00e1t\u00fdch letech minul\u00e9ho stolet\u00ed. Mno\u017estv\u00ed tritia uvoln\u011bn\u00e9ho v\u00a0pr\u016fb\u011bhu test\u016f do atmosf\u00e9ry se odhaduje na 186 EBq (186\u22191018<\/sup> Bq) [3]. V\u011bt\u0161ina test\u016f prob\u00edhala na severn\u00ed polokouli. Jen asi 5\u00a0% uvoln\u011bn\u00e9ho tritia se vlivem stratosf\u00e9rick\u00e9 cirkulace dostalo na ji\u017en\u00ed polokouli [7]. Objemov\u00e1 aktivita tritia ve sr\u00e1\u017ek\u00e1ch v\u00a0dob\u011b kulminace atmosf\u00e9rick\u00fdch test\u016f byla na severn\u00ed polokouli p\u0159ibli\u017en\u011b 600 Bq\/l [4]. Od z\u00e1kazu atmosf\u00e9rick\u00fdch jadern\u00fdch test\u016f v\u00a0roce 1963 doch\u00e1z\u00ed k\u00a0postupn\u00e9mu poklesu glob\u00e1ln\u00ed \u00farovn\u011b tritia v\u00a0\u017eivotn\u00edm prost\u0159ed\u00ed. Z\u00a0uv\u00e1d\u011bn\u00fdch dat [3] m\u016f\u017eeme odhadnout p\u0159\u00edsp\u011bvek tritia z\u00a0jadern\u00fdch test\u016f v\u00a0glob\u00e1ln\u00edm invent\u00e1\u0159i pro rok 2016 na 9,6 EBq, po roce 2050 bude p\u0159\u00edsp\u011bvek srovnateln\u00fd s\u00a0mno\u017estv\u00edm tritia p\u0159irozen\u00e9ho p\u016fvodu (1,3 EBq). Ve srovn\u00e1n\u00ed s\u00a0atmosf\u00e9rick\u00fdmi testy jadern\u00fdch zbran\u00ed jsou ostatn\u00ed antropogenn\u00ed zdroje tritia v\u00a0glob\u00e1ln\u00edm m\u011b\u0159\u00edtku minoritn\u00ed a\u00a0maj\u00ed sp\u00ed\u0161e lok\u00e1ln\u00ed v\u00fdznam [8]. Nap\u0159\u00edklad Unscear uv\u00e1d\u00ed ro\u010dn\u00ed celosv\u011btovou v\u00fdpust tritia do ovzdu\u0161\u00ed v\u00a0devades\u00e1t\u00fdch letech na \u00farovni jednotek PTBq (1015<\/sup> Bq) a\u00a0celosv\u011btovou ro\u010dn\u00ed v\u00fdpust do vodote\u010d\u00ed na \u00farovni 10 PTBq [3].<\/p>\n

Tritium p\u0159irozen\u00e9ho p\u016fvodu i\u00a0p\u016fvodem z\u00a0jadern\u00fdch test\u016f se v\u00a0atmosf\u00e9\u0159e vyskytuje dominantn\u011b ve form\u011b HTO. K\u00a0zemsk\u00e9mu povrchu se dost\u00e1v\u00e1 nejv\u00edce b\u011bhem jara a\u00a0l\u00e9ta. Je to zp\u016fsobeno jarn\u00edm zeslaben\u00edm tropopauzy, kdy doch\u00e1z\u00ed k\u00a0pr\u016fniku stratosf\u00e9rick\u00e9ho vzduchu do troposf\u00e9ry. Tomu odpov\u00edd\u00e1 i\u00a0cyklick\u00fd pr\u016fb\u011bh koncentrac\u00ed tritia ve sr\u00e1\u017ek\u00e1ch. Na severn\u00ed polokouli se jedn\u00e1 o\u00a0zv\u00fd\u0161en\u00e9 hodnoty v\u00a0obdob\u00ed jaro\u2013l\u00e9to a\u00a0nejni\u017e\u0161\u00ed v\u00a0zim\u011b [9].<\/p>\n

Vzhledem k\u00a0v\u00fd\u0161e uveden\u00fdm skute\u010dnostem je tritium v\u00a0chemick\u00e9 form\u011b HTO vyu\u017e\u00edv\u00e1no jako stopova\u010d pro podzemn\u00ed a\u00a0povrchov\u00e9 vody. Nap\u0159\u00edklad pro modelov\u00e1n\u00ed transportu polutant\u016f v\u00a0toku pod jadernou elektr\u00e1rnou [10, 11], v\u00a0podzemn\u00edch vod\u00e1ch [12, 13], tak\u00e9 se pou\u017e\u00edv\u00e1 k\u00a0ur\u010dov\u00e1n\u00ed st\u00e1\u0159\u00ed a\u00a0p\u016fvodu podzemn\u00edch vod. Pro v\u0161echny tyto \u00fa\u010dely je z\u00e1kladn\u00edm p\u0159edpokladem p\u0159esn\u00e9 stanoven\u00ed n\u00edzk\u00fdch objemov\u00fdch aktivit tritia.<\/p>\n

Objemov\u00e1 aktivita tritia ve sr\u00e1\u017ek\u00e1ch je z\u00e1visl\u00e1 p\u0159edev\u0161\u00edm na zem\u011bpisn\u00e9 \u0161\u00ed\u0159ce a\u00a0vzd\u00e1lenosti lokality od oce\u00e1nu. Sou\u010dasn\u00e1 \u00farove\u0148 aktivity tritia ve sr\u00e1\u017ekov\u00fdch vod\u00e1ch ve st\u0159edn\u00edm zem\u011bpisn\u00e9m p\u00e1smu severn\u00ed polokoule v\u00a0kontinent\u00e1ln\u00edch podm\u00ednk\u00e1ch je p\u0159ibli\u017en\u011b 1 Bq\/l. V\u00a0podzemn\u00edch vod\u00e1ch jsou ojedin\u011ble zji\u0161\u0165ov\u00e1ny vy\u0161\u0161\u00ed koncentrace a\u017e n\u011bkolik Bq\/l p\u016fvodem ze sr\u00e1\u017eek v\u00a0obdob\u00ed jadern\u00fdch test\u016f. Na ji\u017en\u00ed polokouli je to z\u00a0d\u016fvodu omezen\u00e9 v\u00fdm\u011bny vzduchu p\u0159es rovn\u00edkov\u00e9 p\u00e1smo v\u00a0dob\u011b vrchol\u00edc\u00edch test\u016f jadern\u00fdch zbran\u00ed m\u00e9n\u011b, p\u0159ibli\u017en\u011b 0,1\u20130,5 Bq\/l [14].<\/p>\n

Pro \u010ceskou republiku nebylo publikov\u00e1no mnoho souhrnn\u00fdch \u00fadaj\u016f o\u00a0objemov\u00fdch aktivit\u00e1ch tritia v\u00a0\u017eivotn\u00edm prost\u0159ed\u00ed, kter\u00e9 by byly vyu\u017eiteln\u00e9 pro v\u00fd\u0161e uveden\u00e9 modely. Existuje celosv\u011btov\u00e1 s\u00ed\u0165, kter\u00e1 zve\u0159ej\u0148uje \u00fadaje o\u00a0izotopech v\u010detn\u011b tritia ve sr\u00e1\u017ek\u00e1ch a\u00a0povrchov\u00fdch vod\u00e1ch (Global Network of Isotopes in Precipitation and Rivers, GNIP, resp. GNIR) [15, 16], kterou zaji\u0161\u0165uje Mezin\u00e1rodn\u00ed atomov\u00e1 agentura se s\u00eddlem ve V\u00eddni. Do t\u00e9to s\u00edt\u011b p\u0159isp\u011bla \u00fadaji z\u00a0\u010cesk\u00e9 republiky pouze jedna stanice sr\u00e1\u017ekov\u00fdch a\u00a0povrchov\u00fdch vod (stanice Uhl\u00ed\u0159sk\u00e1 v\u00a0Jizersk\u00fdch hor\u00e1ch), a\u00a0to za obdob\u00ed 2006\u20132010, resp. 2006\u20132012. \u00dadaje o\u00a0objemov\u00e9 aktivit\u011b tritia ve sr\u00e1\u017ek\u00e1ch a\u00a0povrchov\u00fdch vod\u00e1ch na \u00fazem\u00ed \u010cesk\u00e9 republiky v\u00a0lokalit\u00e1ch p\u0159\u00edmo neovlivn\u011bn\u00fdch provozem jadern\u00fdch elektr\u00e1ren v\u00a0p\u0159ede\u0161l\u00e9m obdob\u00ed publikovali nap\u0159\u00edklad auto\u0159i viz [6, 17\u201319].<\/p>\n

Tento p\u0159\u00edsp\u011bvek se zam\u011b\u0159il na v\u00fdvoj aktivit tritia ve sr\u00e1\u017ek\u00e1ch a\u00a0povrchov\u00fdch vod\u00e1ch bez p\u0159\u00edm\u00e9ho vlivu jadern\u00fdch za\u0159\u00edzen\u00ed v\u00a0\u010cech\u00e1ch, resp. v\u00a0povod\u00ed Vltavy a\u00a0Labe. Hlavn\u00edm c\u00edlem bylo vyhodnotit aktu\u00e1ln\u00ed \u00farove\u0148 aktivity tohoto radionuklidu. Stanoven\u00ed tritia bylo prov\u00e1d\u011bno podle \u010cSN EN 9698 [20], od roku 2010 byly vzorky p\u0159edupravov\u00e1ny elektrolytick\u00fdm nabohacen\u00edm.<\/p>\n

Tabulka 1. Z\u00e1kladn\u00ed charakteristika odb\u011brov\u00fdch m\u00edst
\nTable 1. Characteristics of sampling sites<\/h5>\n\"\"<\/a>\n

Metodika<\/h2>\n

Vzorky sr\u00e1\u017eek byly odeb\u00edr\u00e1ny jedenkr\u00e1t m\u011bs\u00ed\u010dn\u011b (sm\u011bsn\u00fd m\u011bs\u00ed\u010dn\u00ed vzorek) v\u00a0lokalit\u00e1ch Praha-Podbaba, Kocelovice, P\u0159imda, Lu\u017enice nad Lu\u017enic\u00ed, Z\u00e1vi\u0161\u00edn, podrobnosti jsou uvedeny v\u00a0tabulce 1<\/em>. Vzorky povrchov\u00fdch vod byly odeb\u00edr\u00e1ny jedenkr\u00e1t m\u011bs\u00ed\u010dn\u011b v\u00a0profilech Vltava-Hlubok\u00e1 a\u00a0Labe-Lys\u00e1 a\u00a0\u010dtvrtletn\u011b v\u00a0profilech Vltava-Hn\u011bvkovice, Lu\u017enice-Kolod\u011bje a\u00a0Otava-Top\u011blec v\u00a0obdob\u00ed 2002\u20132017 (tabulka 1<\/em>, obr. 1<\/em>).<\/p>\n

Tritium bylo stanoveno podle \u010cSN EN 9698 [20]. Vzorky byly p\u0159edupraveny destilac\u00ed a\u00a0m\u011b\u0159eny v\u00a0p\u0159\u00edstroji Quantulus 1 220, od roku 2010 byly vzorky nejprve elektrolyticky nabohaceny (v\u00fdchoz\u00ed objem vzorku 0,5\u2008l). M\u011b\u0159ena byla sm\u011bs 8\u2008ml vzorku a\u00a012\u2008ml scintila\u010dn\u00edho koktejlu Ultima Gold LLT. K\u00a0omezen\u00ed chemiluminiscence byl vzorek p\u0159ed m\u011b\u0159en\u00edm uchov\u00e1v\u00e1n 12\u00a0hodin v\u00a0temnu. Doba m\u011b\u0159en\u00ed byla 800\u00a0minut, v\u00a0p\u0159\u00edpad\u011b nabohacen\u00fdch vzork\u016f 300\u00a0minut. Ke kalibraci byl pou\u017eit certifikovan\u00fd referen\u010dn\u00ed materi\u00e1l od \u010cMI. Jako slep\u00fd vzorek byla pou\u017eita art\u00e9zsk\u00e1 voda z\u00a0dlouhodob\u011b sledovan\u00e9ho zdroje s\u00a0aktivitou men\u0161\u00ed ne\u017e 0,07 Bq\/l. Nejistota m\u011b\u0159en\u00ed a\u00a0nejmen\u0161\u00ed detekovateln\u00e1 aktivita (cND<\/sub>) na hladin\u011b v\u00fdznamnosti 95\u00a0% byla vyj\u00e1d\u0159ena podle \u010cSN 75 7600 [21]. U\u00a0vzork\u016f bez elektrolytick\u00e9ho nabohacen\u00ed byla cND<\/sub> cca 1 Bq\/l, pro vzorky nabohacen\u00e9 0,07 Bq\/l.<\/p>\n

Hodnoty men\u0161\u00ed ne\u017e cND<\/sub> byly do dal\u0161\u00edho zpracov\u00e1n\u00ed zahrnuty na \u00farovni cND<\/sub>. Pr\u016fm\u011brn\u00e9 hodnoty tritia ve sr\u00e1\u017ek\u00e1ch byly v\u00e1\u017een\u00e9 mno\u017estv\u00edm sr\u00e1\u017eek na konkr\u00e9tn\u00ed stanici.<\/p>\n

Pro popis poklesu objemov\u00fdch aktivit tritia byla pou\u017eita rovnice prvn\u00edho \u0159\u00e1du:<\/p>\n\"\"<\/a>\n\n\n\n\n\n
kde<\/td>\n\u00a0cj<\/sub><\/em><\/td>\nje<\/td>\nro\u010dn\u00ed pr\u016fm\u011brn\u00e1 objemov\u00e1 aktivita tritia v\u00a0povrchov\u00e9 vod\u011b nebo sr\u00e1\u017ek\u00e1ch v\u00a0roce j (Bq\/l),<\/td>\n<\/tr>\n
<\/td>\n\u03bbef<\/sub><\/em><\/td>\n<\/td>\nefektivn\u00ed (pozorovan\u00e1) konstanta ub\u00fdv\u00e1n\u00ed (1\/r),<\/td>\n<\/tr>\n
<\/td>\nt<\/em><\/td>\n<\/td>\ndoba sledov\u00e1n\u00ed.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Statistick\u00e1 v\u00fdznamnost z\u00e1vislosti byla ov\u011b\u0159ena pomoc\u00ed Pearsonova koeficientu. S\u00a0pou\u017eit\u00edm efektivn\u00ed konstanty byl vypo\u010dten pozorovan\u00fd polo\u010das poklesu aktivity Tef<\/sub> (r) [22]:<\/p>\n\"\"<\/a>\n

Pro zji\u0161t\u011bn\u00ed sezonn\u00edch zm\u011bn tritia ve sr\u00e1\u017ek\u00e1ch byly vypo\u010dteny pr\u016fm\u011brn\u00e9 hodnoty v\u00e1\u017een\u00e9 mno\u017estv\u00edm sr\u00e1\u017eek pro jednotliv\u00e1 ro\u010dn\u00ed obdob\u00ed. Pro v\u00fdpo\u010det byly jako jaro vzaty m\u011bs\u00edce b\u0159ezen\u2013kv\u011bten, l\u00e9to \u010derven\u2013srpen, podzim z\u00e1\u0159\u00ed\u2013listopad a\u00a0zima m\u011bs\u00edce prosinec a\u017e \u00fanor [23].<\/p>\n

V\u00fdsledky a\u00a0diskuse<\/h2>\n

V\u00fdvoj objemov\u00e9 aktivity tritia v\u00a0povrchov\u00e9 vod\u011b vyhodnocen\u00e9 jako pr\u016fm\u011br z\u00a0profil\u016f neovlivn\u011bn\u00fdch p\u0159\u00edm\u00fdmi v\u00fdpustmi jadern\u00e9ho za\u0159\u00edzen\u00ed je zachycen na obr. 2<\/em>. Na obr\u00e1zku jsou data porovn\u00e1na s\u00a0v\u00fdsledky pro \u010desk\u00e9 \u00fazem\u00ed publikovan\u00fdmi d\u0159\u00edve a\u00a0d\u00e1le s\u00a0profily uveden\u00fdmi v\u00a0datab\u00e1zi GNIR. Jednak byly pou\u017eity profily v\u00a0N\u011bmecku, kter\u00e9 svoj\u00ed geografickou polohou a\u00a0klimatick\u00fdmi podm\u00ednkami odpov\u00eddaj\u00ed na\u0161im podm\u00ednk\u00e1m, a\u00a0d\u00e1le v\u00fdsledky z\u00a0jedin\u00e9 \u010desk\u00e9 stanice zapojen\u00e9 v\u00a0GNIR.<\/p>\n

Vyhodnocen\u00e9 ro\u010dn\u00ed pr\u016fm\u011brn\u00e9 objemov\u00e9 aktivity v\u00a0povrchov\u00e9 vod\u011b v\u00a0hodnocen\u00e9m \u00fazem\u00ed byly v\u00a0obdob\u00ed 2002\u20132017 v\u00a0rozmez\u00ed 0,87\u20131,43 Bq\/l.<\/p>\n\"\"<\/a>\n

Obr. 1. Mapa odb\u011brov\u00fdch m\u00edst vzork\u016f v\u00a0povod\u00ed Vltavy a\u00a0Labe
\nFig. 1. Map of sampling sites<\/h6>\n

V\u00fdvoj v\u00e1\u017een\u00fdch ro\u010dn\u00edch pr\u016fm\u011brn\u00fdch objemov\u00fdch aktivit tritia ve sr\u00e1\u017ek\u00e1ch v\u00a0\u010desk\u00e9 \u010d\u00e1sti povod\u00ed Labe je uveden na obr. 3<\/em>. V\u00a0grafu je uvedeno i\u00a0srovn\u00e1n\u00ed s\u00a0v\u00fdsledky publikovan\u00fdmi d\u0159\u00edve pro \u010desk\u00e9 \u00fazem\u00ed a\u00a0s\u00a0daty uveden\u00fdmi v\u00a0GNIP. Vyhodnocen\u00e9 v\u00e1\u017een\u00e9 ro\u010dn\u00ed pr\u016fm\u011brn\u00e9 aktivity v\u00a0hodnocen\u00e9m obdob\u00ed 2001\u20132017 byly v\u00a0rozmez\u00ed 0,94\u20131,38 Bq\/l.<\/p>\n

Pozorovan\u00e9 ro\u010dn\u00ed pr\u016fm\u011brn\u00e9 objemov\u00e9 aktivity tritia ve sr\u00e1\u017ek\u00e1ch a povrchov\u00e9 vod\u011b jsou p\u0159ibli\u017en\u011b 1 Bq\/l a\u00a0jsou srovnateln\u00e9 s\u00a0v\u00fdsledky uv\u00e1d\u011bn\u00fdmi v\u00a0datab\u00e1z\u00edch GNIR a\u00a0GNIP pro stanice ve srovnateln\u00fdch geografick\u00fdch podm\u00ednk\u00e1ch (severn\u00ed polokoule, st\u0159edn\u00ed zem\u011bpisn\u00e1 \u0161\u00ed\u0159ka, kontinent\u00e1ln\u00ed charakter). Tyto aktivity jsou st\u00e1le vy\u0161\u0161\u00ed, ne\u017e je \u00farove\u0148 tritia odpov\u00eddaj\u00edc\u00ed p\u0159irozen\u00e9mu pozad\u00ed tritia a\u00a0ne\u017e aktivity pozorovan\u00e9 na ji\u017en\u00ed polokouli, kde se \u00farove\u0148 tritia dostala p\u0159ibli\u017en\u011b na \u00farove\u0148 charakteristickou pro obdob\u00ed p\u0159ed jadern\u00fdmi testy [7, 14, 24].<\/p>\n\"\"<\/a>\n

Obr. 2. V\u00fdvoj objemov\u00fdch aktivit tritia v povrchov\u00fdch vod\u00e1ch na \u00fazem\u00ed povod\u00ed Labe ve srovn\u00e1n\u00ed s d\u0159\u00edve publikovan\u00fdmi v\u00fdsledky pro \u010cR a s daty uveden\u00fdmi v GNIR (N\u011bmecko, \u010cR)
\nFig. 2. Comparison of tritium concentrations in surface water in Elbe River Basin with data from GNIR and previously published data for the Czech Republic<\/h6>\n

S\u00a0pou\u017eit\u00edm rovnice (1) byl hodnocen trend poklesu ro\u010dn\u00edch pr\u016fm\u011brn\u00fdch objemov\u00fdch aktivit tritia v\u00a0povrchov\u00fdch vod\u00e1ch i\u00a0sr\u00e1\u017ek\u00e1ch. V\u00a0p\u0159\u00edpad\u011b povrchov\u00fdch vod byl pro obdob\u00ed 2001\u20132017 nalezen statisticky v\u00fdznamn\u00fd trend poklesu, ov\u0161em s\u00a0polo\u010dasem vypo\u010dten\u00fdm podle rovnice (2) 28,3 \u00b1 9,0\u00a0let, co\u017e je hodnota v\u00fdznamn\u011b vy\u0161\u0161\u00ed, ne\u017e je polo\u010das p\u0159em\u011bny tritia 12,32\u00a0let [1]. D\u016fvodem mohou b\u00fdt sou\u010dasn\u00e9 zdroje tritia: a) antropogenn\u00ed, zejm\u00e9na\u00a0jadern\u00e9 elektr\u00e1rny v\u00a0\u010cR a\u00a0v\u00a0zahrani\u010d\u00ed (ze kter\u00fdch se k\u00a0n\u00e1m dost\u00e1v\u00e1 atmosf\u00e9rick\u00fdm p\u0159enosem), b) p\u0159irozen\u00e1 produkce tohoto radionuklidu. Korekce pro v\u00fdpo\u010det polo\u010dasu poklesu aktivity (odpov\u00eddaj\u00edc\u00ed hodnot\u011b objemov\u00e9 aktivity pro stabiln\u00ed p\u0159\u00edsun tritia z\u00a0t\u011bchto zdroj\u016f) byla odhadnuta na z\u00e1klad\u011b publikovan\u00fdch \u00fadaj\u016f. Podle autor\u016f publikace [5] \u010dinila tato hodnota 0,48 Bq\/l (0,38 Bq\/l odhadovan\u00e1 aktivita odpov\u00eddaj\u00edc\u00ed p\u0159irozen\u00e9 produkci a\u00a00,1 Bq\/l aktivita odpov\u00eddaj\u00edc\u00ed p\u0159enosu tritia z\u00a0jadern\u00fdch elektr\u00e1ren), podle \u00fadaj\u016f z\u00a0publikace [4] byla pou\u017eita hodnota 0,6 Bq\/l (auto\u0159i uv\u00e1d\u00ed pro odhad odpov\u00eddaj\u00edc\u00ed pouze p\u0159irozen\u00e9 produkci). Vypo\u010dten\u00e9 hodnoty efektivn\u00edch polo\u010das\u016f poklesu aktivity pak byly 15,9 \u00b1 4,8\u00a0let podle\u00a0[6] a\u00a012,7 \u00b1 3,7\u00a0let podle [4], jak je uvedeno v\u00a0tabulce 2<\/em>. S\u00a0p\u0159ihl\u00e9dnut\u00edm k\u00a0nejistot\u00e1m vypo\u010dten\u00fdch polo\u010das\u016f jde v\u00a0obou p\u0159\u00edpadech o\u00a0hodnoty odpov\u00eddaj\u00edc\u00ed p\u0159ibli\u017en\u011b polo\u010dasu p\u0159em\u011bny tritia. Pro \u00fazem\u00ed \u010cesk\u00e9 republiky se jev\u00ed jako p\u0159esn\u011bj\u0161\u00ed odhad vych\u00e1zej\u00edc\u00ed z\u00a0rovnov\u00e1\u017en\u00e9 hodnoty objemov\u00e9 aktivity 0,6\u00a0Bq\/l, jeliko\u017e je zat\u00ed\u017een men\u0161\u00ed nejistotou. Z\u00a0v\u00fdpo\u010dtu vypl\u00fdv\u00e1, \u017ee p\u0159\u00edsp\u011bvek jadern\u00fdch elektr\u00e1ren na na\u0161em \u00fazem\u00ed je velmi mal\u00fd a\u00a0v\u00a0r\u00e1mci nejistot jej m\u016f\u017eeme zanedbat. V\u00a0budoucnu ov\u0161em s\u00a0rozv\u00edjej\u00edc\u00ed se sv\u011btovou jadernou energetikou a\u00a0dal\u0161\u00edm poklesem \u201ebombov\u00e9ho\u201c tritia m\u016f\u017ee jeho v\u00fdznam nar\u016fst.<\/p>\n\"\"<\/a>\n

Obr. 3. V\u00fdvoj objemov\u00fdch aktivit tritia ve sr\u00e1\u017ek\u00e1ch na \u00fazem\u00ed povod\u00ed Labe ve srovn\u00e1n\u00ed s d\u0159\u00edve publikovan\u00fdmi v\u00fdsledky pro \u010cR a s daty uveden\u00fdmi v GNIP (N\u011bmecko, Rakousko, \u010cR)
\nFig. 3. Comparison of tritium concentrations in precipitation in Elbe River Basin with data from GNIP and previously published data for the Czech Republic<\/h6>\n

Obdobn\u011b byl analyzov\u00e1n trend poklesu objemov\u00fdch aktivit tritia ve sr\u00e1\u017ek\u00e1ch. V\u00a0obdob\u00ed po roce 2002 nebyl pozorov\u00e1n statisticky v\u00fdznamn\u00fd trend poklesu objemov\u00fdch aktivit tritia ve sr\u00e1\u017ek\u00e1ch ani p\u0159i anal\u00fdze korigovan\u00fdch hodnot jak postupem podle [6], tak i\u00a0[4], kter\u00fd byl pozorov\u00e1n v\u00a0p\u0159edchoz\u00edch obdob\u00edch (obr. 2<\/em> a\u00a03<\/em>), v\u00a0\u010cesk\u00e9 republice je\u0161t\u011b v\u00a0devades\u00e1t\u00fdch letech [6].<\/p>\n

D\u00e1le byla hodnocena sezonn\u00ed variabilita tritia ve sr\u00e1\u017ek\u00e1ch v\u00a0obdob\u00ed 2010\u20132017, kdy byly vzorky ze stanic Praha-Podbaba, Kocelovice a\u00a0Lu\u017enice (sledov\u00e1n\u00ed ukon\u010deno 2012) elektrolyticky nabohaceny. Pr\u016fb\u011bh objemov\u00fdch aktivit na t\u011bchto stanic\u00edch je uveden na obr. 4<\/em>. U\u00a085\u00a0% zji\u0161t\u011bn\u00fdch hodnot bylo rozmez\u00ed 0,5\u20131,5 Bq\/l, jen asi 4\u00a0% z\u00a0celkov\u00e9ho po\u010dtu hodnot p\u0159es\u00e1hlo 2 Bq\/l (p\u0159esn\u00e1 p\u0159\u00ed\u010dina odlehl\u00fdch hodnot nebyla zkoum\u00e1na).<\/p>\n\"\"<\/a>\n

Obr. 4. V\u00fdvoj objemov\u00e9 aktivity tritia ve sr\u00e1\u017ek\u00e1ch na vybran\u00fdch profilech v obdob\u00ed 2010\u20132017
\nFig. 4. Tritium concentrations in precipitation from selected monitoring sites in the period 2010\u20132017<\/h6>\n

Byly hodnoceny pr\u016fm\u011brn\u00e9 hodnoty objemov\u00fdch aktivit (v\u00e1\u017een\u00e9 sr\u00e1\u017ekov\u00fdmi \u00fahrny) pro jednotliv\u00e1 ro\u010dn\u00ed obdob\u00ed, kter\u00e9 jsou zobrazeny na obr. 5<\/em>. Vy\u0161\u0161\u00ed pr\u016fm\u011brn\u00e9 hodnoty byly pozorov\u00e1ny v\u00a0jarn\u00edm a\u00a0letn\u00edm obdob\u00ed, nejni\u017e\u0161\u00ed v\u00a0zim\u011b. Sezonn\u00ed variabilita tritia ve sr\u00e1\u017ek\u00e1ch souvis\u00ed s\u00a0pohyby vzdu\u0161n\u00fdch mas, kdy v\u00a0d\u016fsledku oh\u0159evu kontinent\u016f doch\u00e1z\u00ed k\u00a0vzestupu tropopauzy nejv\u00edce v\u00a0jarn\u00edm obdob\u00ed a\u00a0k\u00a0pr\u016fniku stratosf\u00e9rick\u00e9ho vzduchu s\u00a0vy\u0161\u0161\u00edm obsahem tritia k\u00a0zemsk\u00e9mu povrchu [25].<\/p>\n

Tabulka 2. Vypo\u010dten\u00e9 efektivn\u00ed polo\u010dasy (bez a\u00a0s\u00a0korekc\u00ed o\u00a0p\u0159\u00edsp\u011bvek tritia p\u0159irozen\u00e9ho p\u016fvodu, p\u0159\u00edpadn\u011b p\u0159enosem z\u00a0jadern\u00fdch za\u0159\u00edzen\u00ed jinde ve sv\u011bt\u011b)
\nTable 2. Evaluated effective half-lives of tritium concentration decrease in surface water (without and with correction for the natural component and the contribution from nuclear facilities worldwide) in the period 2002\u20132017<\/h5>\n\"\"<\/a>\n

Z\u00e1v\u011br<\/h2>\n

S\u00a0vyu\u017eit\u00edm citliv\u00e9ho stanoven\u00ed v\u010detn\u011b elektrolytick\u00e9ho nabohacen\u00ed je mo\u017en\u00e9 stanovit velmi n\u00edzk\u00e9 objemov\u00e9 aktivity tritia, kter\u00e9 maj\u00ed \u0161irok\u00e9 uplatn\u011bn\u00ed nap\u0159. v\u00a0oblasti hydrogeologick\u00e9ho modelov\u00e1n\u00ed. Zp\u0159esn\u011bn\u00ed hodnot aktivity tritia p\u0159isp\u011blo i\u00a0k\u00a0redukci rozptyl\u016f pozorovan\u00fdch hodnot objemov\u00fdch aktivit.<\/p>\n\"\"<\/a>\n

Obr. 5. Pr\u016fm\u011brn\u00e9 hodnoty (v\u00e1\u017een\u00e9) objemov\u00fdch aktivit tritia ve sr\u00e1\u017ek\u00e1ch pro jednotliv\u00e1 ro\u010dn\u00ed obdob\u00ed v obdob\u00ed 2010\u20132017
\nFig. 5. Seasonal average tritium concentrations weighted by quantity of precipitation for the period 2010\u20132017<\/h6>\n

Hlavn\u00edm c\u00edlem p\u0159\u00edsp\u011bvku bylo vyhodnotit aktu\u00e1ln\u00ed \u00farove\u0148 tritia ve sr\u00e1\u017ek\u00e1ch a\u00a0povrchov\u00e9 vod\u011b na \u00fazem\u00ed povod\u00ed Labe na profilech p\u0159\u00edmo neovlivn\u011bn\u00fdch v\u00fdpustmi z\u00a0jadern\u00fdch za\u0159\u00edzen\u00ed (p\u0159edev\u0161\u00edm JE Temel\u00edn a\u00a0\u00daJV \u0158e\u017e). Zji\u0161t\u011bn\u00e9 objemov\u00e9 aktivity na \u00farovni p\u0159ibli\u017en\u011b 1 Bq\/l odpov\u00eddaj\u00ed geografick\u00fdm podm\u00ednk\u00e1m. Tyto aktivity jsou st\u00e1le vy\u0161\u0161\u00ed, ne\u017e je p\u0159irozen\u00e1 \u00farove\u0148, ale p\u0159\u00edsp\u011bvek tritia ze sou\u010dasn\u00fdch zdroj\u016f za\u010d\u00edn\u00e1 p\u0159eva\u017eovat nad tritiem poch\u00e1zej\u00edc\u00edm z\u00a0jadern\u00fdch test\u016f. Po roce 2001 u\u017e nen\u00ed patrn\u00fd dal\u0161\u00ed pokles aktivity tritia ve sr\u00e1\u017ek\u00e1ch tak, jak tomu bylo v\u00a0p\u0159ede\u0161l\u00e9m obdob\u00ed.<\/p>\n","protected":false},"excerpt":{"rendered":"

Past tests of nuclear weapons in the atmosphere, nuclear energy facilities and tritium of natural origin are main sources of tritium in the environment. Thanks to its presence in environment and its favourable properties, tritium is used as a\u00a0radiotracer. <\/p>\n","protected":false},"author":8,"featured_media":4913,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[2,86,87],"tags":[1286,577,316],"coauthors":[327,238,239,237],"class_list":["post-4989","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-from-the-world-of-water-management","category-hydraulics-hydrology-and-hydrogeology","category-hydrochemistry-radioecology-microbiology","tag-electrolytic-enrichment","tag-precipitation","tag-surface-water"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/4989","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/comments?post=4989"}],"version-history":[{"count":2,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/4989\/revisions"}],"predecessor-version":[{"id":30469,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/posts\/4989\/revisions\/30469"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media\/4913"}],"wp:attachment":[{"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/media?parent=4989"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/categories?post=4989"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/tags?post=4989"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.vtei.cz\/en\/wp-json\/wp\/v2\/coauthors?post=4989"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}