Perceived Value of Mobile Service Use and its Consequences

The thesis is positioned in the services marketing field. Previous mobile service research has identified perceived value or relative advantage as a stable predictor of use of services. However, a more detailed view of what customers value in mobile services is needed for marketing diverse types of mobile content and attracting committed customers. The direct relationships between multidimensional value and loyalty constructs have received limited attention in the previous literature, although a multidimensional view is needed for differentiating services. This thesis studies how perceived value of mobile service use affects customer commitment, repurchase intentions, word-of-mouth and willingness to pay. The doctoral thesis consists of three journal articles and one working paper. The four papers have different sub-aims and comprise individual empirical studies. Mixed methods including both personal interviews and survey data collected from end-users of different types of mobile content services are used. The conceptual mobile perceived value model that results from the first explorative empirical study supports a six- dimensional value view. The six dimensions are further categorized into two higher order constructs: content-related perceived value (emotional, social, convenience and monetary value) and context-related (epistemic and conditional value) perceived value. Structural equation modeling is used in the other three studies to validate this framework by analyzing the relationships between context- and content-related value, and how the individual perceived value dimensions affect commitment and behavioral outcomes. Analyzing the direct relationships revealed differences in the effect of perceived value dimensions between information and entertainment mobile service user groups, between effects on commitment, repurchase intentions and word-of-mouth intentions, as well as between effects on commitment to the provider and to the mobile channel as such. This thesis contributes to earlier perceived value literature by structuring the value dimensions into two groups. Most importantly, the thesis contributes to the value and loyalty literature by increasing understanding of how the different dimensions of perceived value directly affect commitment and post-purchase intentions. The results have implications for further theory development in the electronic services field using multidimensional latent constructs, and practical implications for enhancing commitment to content provider and for differentiated marketing strategies in the mobile field. The general conclusion of this thesis is that differentiated value-based marketing of mobile services is essential for attracting committed customers who will use the same providers��� content also in the future. Minna Pihlstr��m is associated with the Centre for Relationship Marketing and Service Management (CERS) at Hanken.

Archaea, Bacteria, and methane production along environmental gradients in fens and bogs

Metanogeenit ovat hapettomissa oloissa el��vi�� arkkien p����ryhm����n kuuluvia mikrobeja, joiden ainutlaatuisen aineenvaihdunnan seurauksena syntyy metaania. Ilmakeh��ss�� metaani on voimakas kasvihuonekaasu. Yksi suurimmista luonnon metaanil��hteist�� ovat kosteikot. Pohjoisten soiden metaanip����st��t vaihtelevat voimakkaasti eri soiden v��lill�� ja yhden suon sis��ll��kin, riippuen muun muassa vuodenajasta, suotyypist�� ja kasvillisuudesta. V��it��skirjaty��ss�� tutkittiin metaanip����st��jen vaihtelun mikrobiologista taustaa. Tutkimuksessa selvitettiin suotyypin, vuodenajan, tuhkalannoituksen ja turvesyvyyden vaikutusta metanogeeniyhteis��ihin sek�� metaanintuottoon kolmella suomalaisella suolla. Lis��ksi tutkittiin ei-metanogeenisia arkkeja ja bakteereita, koska ne muodostavat metaanin tuoton l��ht��aineet osana hapetonta hajotusta. Mikrobiyhteis��t analysoitiin DNA- ja RNA-l��ht��isill��, polymeraasiketjureaktioon (PCR) perustuvilla menetelmill��. Merkkigeenein�� k��ytettiin metaanin tuottoon liittyv���� mcrA-geeni�� sek�� arkkien ja bakteerien ribosomaalista 16S RNA-geeni��. Metanogeeniyhteis��t ja metaanintuotto erosivat huomattavasti happaman ja v��h��ravinteisen rahkasuon sek�� ravinteikkaampien sarasoiden v��lill��. Rahkasuolta l��ytyi l��hes yksinomaan Methanomicrobiales-lahkon metanogeeneja, jotka tuottavat metaania vedyst�� ja hiilidioksidista. Sarasoiden metanogeeniyhteis��t olivat monimuotoisempia, ja niill�� esiintyi my��s asetaattia k��ytt��vi�� metanogeeneja. Vuodenaika vaikutti merkitt��v��sti metaanintuottoon. Talvella havaittiin odottamattoman suuri metaanintuottopotentiaali sek�� viitteit�� aktiivisista metanogeeneista. Arkkiyhteis��n koostumus sen sijaan vaihteli vain v��h��n. Tuhkalannoitus, jonka tarkoituksena on edist���� puiden kasvua ojitetuilla soilla, ei merkitt��v��sti vaikuttanut metaanintuottoon tai -tuottajiin. Ojitetun suon yhteis��t kuitenkin muuttuivat turvesyvyyden mukaan. Vertailtaessa erilaisia PCR-menetelmi�� todettiin, ett�� kolmella mcrA-geeniin kohdistuvalla alukeparilla havaittiin p����osin samat ojitetun suon metanogeenit, mutta lajien runsaussuhteet riippuvat k��ytetyist�� alukkeista. Soilla havaitut bakteerit kuuluivat p����jaksoihin Deltaproteobacteria, Acidobacteria ja Verrucomicrobia. Lis��ksi l��ydettiin Crenarchaeota-p����jakson ryhmiin 1.1c ja 1.3 kuuluvia ei-metanogeenisia arkkeja. Tulokset ryhmien esiintymisest�� hapettomassa turpeessa antavat l��ht��kohdan selvitt���� niiden mahdollisia vuorovaikutuksia metanogeenien kanssa. Tutkimuksen tulokset osoittivat, ett�� metanogeeniyhteis��n koostumus heijastaa metaanintuottoon vaikuttavia kemiallisia tai kasvillisuuden vaihteluita kuten suotyyppi��. Soiden metanogeenien ja niiden fysiologian parempi tuntemus voi auttaa ennustamaan ymp��rist��muutosten vaikutusta soiden metaanip����st��ihin.

Influence of harvesting strategy on nutrient supply and production of dairy cows consuming diets based on grass and red clover silage

The main objective of this thesis was to elucidate the effects of regrowth grass silage and red clover silage on nutrient supply and milk production of dairy cows as compared with primary growth grass silages. In the first experiment (publication I), two primary growth and four regrowth grass silages were harvested at two stages of growth. These six silages were fed to 24 lactating dairy cows with two levels of concentrate allowance. Silage intake and energy corrected milk yield (ECM) responses, and the range in these response variables between the diets, were smaller when regrowth silages rather than primary growth silages were fed. Milk production of dairy cows reflected the intake of metabolizable energy (ME), and no differences in the ME utilization were found between the diets based on silages harvested from primary growth and regrowth. The ECM response to increased concentrate allowance was, on average, greater when regrowth rather than primary growth silages were fed. In the second experiment (publication II), two silages from primary growth and two from regrowth used in I were fed to rumen cannulated lactating dairy cows. Cows consumed less feed dry matter (DM), energy and protein, and produced less milk, when fed diets based on regrowth silages rather than primary growth silages. Lower milk production responses of regrowth grass silage diets were mainly due to the lower silage DM intake, and could not be accounted for by differences in energy or protein utilization. Regrowth grass silage intake was not limited due to neutral detergent fibre (NDF) digestion or rumen fill or passage kinetics. However, lower intake may be at least partly attributable to plant diseases such as leaf spot infections, dead deteriorating material or abundance of weeds, which are all higher in regrowth compared with primary growth, and increase with advancing regrowth. In the third experiment (publications III and IV), red clover silages and grass silages harvested at two stages of growth, and a mixed diet of red clover and grass silages, were fed to five rumen cannulated lactating dairy cows. In spite of the lower average ME intake for red clover diets, the ECM production remained unchanged suggesting more efficient utilisation of ME for red clover diets compared with grass diets. Intake of N, and omasal canal flows of total non-ammonia N (NAN), microbial and non-microbial NAN were higher for red clover than for grass silage diets, but were not affected by forage maturity. Delaying the harvest tended to decrease DM intake of grass silage and increase that of red clover silage. The digestion rate of potentially digestible NDF was faster for red clover diets than for grass silage diets. Delaying the harvest decreased the digestion rate for grass but increased it for red clover silage diets. The low intake of early-cut red clover silage could not be explained by silage digestibility, fermentation quality, or rumen fill but was most likely related to the nutritionally suboptimal diet composition because inclusion of moderate quality grass silage in mixed diet increased silage DM intake. Despite the higher total amino acid supply of cows fed red clover versus grass silage diets, further milk production responses on red clover diets were possibly compromised by an inadequate supply of methionine as evidenced by lower methionine concentration in the amino acid profile of omasal digesta and plasma. Increasing the maturity of ensiled red clover does not seem to affect silage DM intake as consistently as that of grasses. The efficiency of N utilization for milk protein synthesis was lower for red clover diets than for grass diets. It was negatively related to diet crude protein concentration similarly to grass silage diets.

Characterisation, cloning and production of industrially interesting enzymes: gluconolactone oxidase of Penicillium cyaneo-fulvum and gluconate 5-dehydrogenase of Gluconobacter suboxydans

The work covered in this thesis is focused on the development of technology for bioconversion of glucose into D-erythorbic acid (D-EA) and 5-ketogluconic acid (5-KGA). The task was to show on proof-of-concept level the functionality of the enzymatic conversion or one-step bioconversion of glucose to these acids. The feasibility of both studies to be further developed for production processes was also evaluated. The glucose - D-EA bioconversion study was based on the use of a cloned gene encoding a D-EA forming soluble flavoprotein, D-gluconolactone oxidase (GLO). GLO was purified from Penicillium cyaneo-fulvum and partially sequenced. The peptide sequences obtained were used to isolate a cDNA clone encoding the enzyme. The cloned gene (GenBank accession no. AY576053) is homologous to the other known eukaryotic lactone oxidases and also to some putative prokaryotic lactone oxidases. Analysis of the deduced protein sequence of GLO indicated the presence of a typical secretion signal sequence at the N-terminus of the enzyme. No other targeting/anchoring signals were found, suggesting that GLO is the first known lactone oxidase that is secreted rather than targeted to the membranes of the endoplasmic reticulum or mitochondria. Experimental evidence supports this analysis, as near complete secretion of GLO was observed in two different yeast expression systems. Highest expression levels of GLO were obtained using Pichia pastoris as an expression host. Recombinant GLO was characterised and the suitability of purified GLO for the production of D-EA was studied. Immobilised GLO was found to be rapidly inactivated during D-EA production. The feasibility of in vivo glucose - D-EA conversion using a P. pastoris strain co-expressing the genes of GLO and glucose oxidase (GOD, E.C. 1.1.3.4) of A. niger was demonstrated. The glucose - 5-KGA bioconversion study followed a similar strategy to that used in the D-EA production research. The rationale was based on the use of a cloned gene encoding a membrane-bound pyrroloquinoline quinone (PQQ)-dependent gluconate 5-dehydrogenase (GA 5-DH). GA 5-DH was purified to homogeneity from the only source of this enzyme known in literature, Gluconobacter suboxydans, and partially sequenced. Using the amino acid sequence information, the GA 5-DH gene was cloned from a genomic library of G. suboxydans. The cloned gene was sequenced (GenBank accession no. AJ577472) and found to be an operon of two adjacent genes encoding two subunits of GA 5-DH. It turned out that GA 5-DH is a rather close homologue of a sorbitol dehydrogenase from another G. suboxydans strain. It was also found that GA 5-DH has significant polyol dehydrogenase activity. The G. suboxydans GA 5-DH gene was poorly expressed in E. coli. Under optimised conditions maximum expression levels of GA 5-DH did not exceed the levels found in wild-type G. suboxydans. Attempts to increase expression levels resulted in repression of growth and extensive cell lysis. However, the expression levels were sufficient to demonstrate the possibility of bioconversion of glucose and gluconate into 5-KGA using recombinant strains of E. coli. An uncharacterised homologue of GA 5-DH was identified in Xanthomonas campestris using in silico screening. This enzyme encoded by chromosomal locus NP_636946 was found by a sequencing project of X. campestris and named as a hypothetical glucose dehydrogenase. The gene encoding this uncharacterised enzyme was cloned, expressed in E. coli and found to encode a gluconate/polyol dehydrogenase without glucose dehydrogenase activity. Moreover, the X. campestris GA 5-DH gene was expressed in E. coli at nearly 30 times higher levels than the G. suboxydans GA 5-DH gene. Good expressability of the X. campestris GA-5DH gene makes it a valuable tool not only for 5-KGA production in the tartaric acid (TA) bioprocess, but possibly also for other bioprocesses (e.g. oxidation of sorbitol into L-sorbose). In addition to glucose - 5-KGA bioconversion, a preliminary study of the feasibility of enzymatic conversion of 5-KGA into TA was carried out. Here, the efficacy of the first step of a prospective two-step conversion route including a transketolase and a dehydrogenase was confirmed. It was found that transketolase convert 5-KGA into TA semialdehyde. A candidate for the second step was suggested to be succinic dehydrogenase, but this was not tested. The analysis of the two subprojects indicated that bioconversion of glucose to TA using X. campestris GA 5-DH should be prioritised first and the process development efforts in future should be focused on development of more efficient GA 5-DH production strains by screening a more suitable production host and by protein engineering.

The connection between on-farm assessed welfare (A-index) and production parameters of the sows

T��m��n tutkimuksen tavoitteena oli selvitt���� tilalla m����ritetyn hyvinvoinnin yhteytt�� emakoiden tuotantotuloksiin. Hyvinvointia arvioitiin suomalaisen hyvinvointi-indeksin, A-indeksi, avulla. Tuotantotuloksina k��ytettiin kahta erilaista tuotosaineistoa, jotka molemmat pohjautuivat kansalliseen tuotosseuranta aineistoon. Hyvinvointim����ritykset tehtiin 30 porsastuotantosikalassa maaliskuun 2007 aikana. A-indeksi koostuu kuudesta kategoriasta ���liikkumismahdollisuudet���, ���alustan ominaisuudet���, ���sosiaaliset kontaktit���, ���valo, ilma ja melu���, ���ruokinta ja veden saanti��� sek�� ���el��inten terveys ja hoidon taso���. Jokaisessa kategoriassa on 3-10 p����osin ymp��rist��per��ist�� muuttujaa, jotka vaihtelevat osastoittain. Maksimipistem����r�� osastolle on 100. Hyvinvointimittaukset tehtiin porsitus-, tiineytys- ja joutilasosastoilla. Erillisten tiineytysosastojen pienen lukum����r��n takia (n=7) tilakohtaiset tiineytys- ja joutilasosastopisteet yhdistettiin ja keskiarvoja k��ytettiin analyyseiss��. Yhteyksi�� tuotokseen tutkittiin kahden eri aineiston avulla 1) Tilaraportti aineisto (n=29) muodostuu muokkaamattomista tila- ja tuotostuloksista tilavierailua edelt��v��n vuoden ajalta, 2) POTSIaineisto (n=30) muodostuu POTSI-ohjelmalla (MTT) muokatusta tuotantoaineistosta, joka sis��lt���� managementtiryhm��n (tila, vuosi, vuodenaika) vaikutuksen ensikoiden ja emakoiden pahnuekohtaiseen tuotokseen. Yhteyksi�� analysointiin korrelaatio- ja regressioanalyysien avulla. Vaikka osallistuminen tutkimukseen oli vapaaehtoista, molempien tuotantoaineistojen perusteella tutkimustilat edustavat keskituottoista suomalaista sikatilaa. A-indeksin kokonaispisteet vaihtelivat v��lill�� 37,5���64,0 porsitusosastolla ja 39,5���83,5 joutilasosastolla. Tilaraporttiaineistoa k��ytett��ess�� paremmat pisteet porsitusosaston ���el��inten terveys ja hoidon taso��� -kategoriasta lyhensiv��t el��inten lis����ntymissykli��, lis��siv��t syntyvien pahnueiden ja porsaiden m����r���� sek�� alensivat kuolleena syntyneiden lukum����r����. Regressiomallin mukaan ���el��inten terveys ja hoidon taso��� -kategoria selitti syntyvien porsaiden lukum����r��n, porsimisv��lin pituuden sek�� keskiporsimiskerran vaihtelua. Paremmat pisteet joutilasosaston ���liikkumismahdollisuudet��� kategoriasta alensivat syntyneiden pahnueiden sek�� syntyneiden ett�� vieroitettujen porsaiden lukum����r����. Regressiomallin mukaan ensikkopahnueiden osuus ja ���liikkumismahdollisuudet��� kategorian pisteet selittiv��t vieroitettujen porsaiden lukum����r��n vaihtelua. POTSI-aineiston yhteydess�� kuolleena syntyneiden porsaiden lukum����r��n aleneminen oli ensikoilla yhteydess�� parempiin porsitusosaston ���sosiaalisiin kontakteihin��� ja emakoilla puolestaan joutilasosaston parempiin ���el��inten terveys ja hoidon taso��� pisteisiin. Kahden eri tuotantoaineiston avulla saadut tulokset erosivat toisistaan. Seuraavissa tutkimuksissa onkin suositeltavampaa k��ytt���� Tilaraporttiaineistoja, joissa tuotokset ilmoitetaan vuosikohtaisina. T��m��n tutkimuksen perusteella hyvinvoinnilla ja tuotoksella on yhteyksi��, joilla on my��s merkitt��v���� taloudellista vaikutusta. Erityisesti hyv�� el��inten hoito ja el��inten terveys lis����v��t tuotettujen porsaiden m����r���� ja lyhent��v��t lis����ntymiskiertoa. Erityishuomiota tulee kiinnitt���� vapaana olevien joutilaiden emakoiden sosiaaliseen stressiin ja rehunsaannin varmistamiseen kaikille yksil��ille.

Development of radiosynthesis methods for 18F-labelled radiopharmaceuticals : General considerations and production of a dopamine transporter radioligand

Positron emission tomography (PET) is a molecular imaging technique that utilises radiopharmaceuticals (radiotracers) labelled with a positron-emitting radionuclide, such as fluorine-18 (18F). Development of a new radiotracer requires an appropriate radiosynthesis method: the most common of which with 18F is nucleophilic substitution with [18F]fluoride ion. The success of the labelling reaction is dependent on various factors such as the reactivity of [18F]fluoride, the structure of the target compound in addition to the chosen solvent. The overall radiosynthesis procedure must be optimised in terms of radiochemical yield and quality of the final product. Therefore, both quantitative and qualitative radioanalytical methods are essential in developing radiosynthesis methods. Furthermore, biological properties of the tracer candidate need to be evaluated by various pre-clinical studies in animal models. In this work, the feasibility of various nucleophilic 18F-fluorination strategies were studied and a labelling method for a novel radiotracer, N-3-[18F]fluoropropyl-2beta-carbomethoxy-3beta-4-fluorophenyl)nortropane ([18F]beta-CFT-FP), was optimised. The effect of solvent was studied by labelling a series of model compounds, 4-(R1-methyl)benzyl R2-benzoates. 18F-Fluorination reactions were carried out both in polar aprotic and protic solvents (tertiary alcohols). Assessment of the 18F-fluorinated products was studied by mass spectrometry (MS) in addition to conventional radiochromatographic methods, using radiosynthesis of 4-[18F]fluoro-N-[2-[1-(2-methoxyphenyl)-1-piperazinyl]ethyl-N-2-pyridinyl-benzamide (p-[18F]MPPF) as a model reaction. Labelling of [18F]beta-CFT-FP was studied using two 18F-fluoroalkylation reagents, [18F]fluoropropyl bromide and [18F]fluoropropyl tosylate, as well as by direct 18F-fluorination of sulfonate ester precursor. Subsequently, the suitability of [18F]beta-CFT-FP for imaging dopamine transporter (DAT) was evaluated by determining its biodistribution in rats. The results showed that protic solvents can be useful co-solvents in aliphatic 18F-fluorinations, especially in the labelling of sulfonate esters. Aromatic 18F-fluorination was not promoted in tert-alcohols. Sensitivity of the ion trap MS was sufficient for the qualitative analysis of the 18F-labelled products; p-[18F]MPPF was identified from the isolated product fraction with a mass-to-charge (m/z) ratio of 435 (i.e. protonated molecule [M+H]+). [18F]beta-CFT-FP was produced most efficiently via [18F]fluoropropyl tosylate, leading to sufficient radiochemical yield and specific radioactivity for PET studies. The ex vivo studies in rats showed fast kinetics as well as the specific uptake of [18F]beta-CFT-FP to the DAT rich brain regions. Thus, it was concluded that [18F]beta-CFT-FP has potential as a radiotracer for imaging DAT by PET.

Impact of Tobacco Control Policy on Smoking and Exposure to Environmental Tobacco Smoke

The aim of the study was to evaluate the impact of the Finnish tobacco control measures for reduction of smoking. First, the trends and patterns in ever smoking among adult Finns in 1978 2001 as well as the associations of trends with the Tobacco Control Act in 1976 were examined. Secondly, the impact of the 1976 TCA on the proportion of ever daily smokers in different socioeconomic groups was studied. Thirdly, the impact of the 1995 TCAA on recent trends in the prevalence of daily smoking was evaluated by gender and employment status. Fourthly, the trends of exposure to environmental tobacco smoke (ETS) at workplaces and homes were investigated. The study is based on data of the Health Behaviour among the Finnish Adult Population surveys. Among Finnish men smoking initiation declined from earlier to later cohorts, whereas among women it increased in successive birth cohorts born before 1956. The lasting differences between birth cohorts as regards ever daily smoking reflected well the impact of measures to reduce smoking in Finland in 1976. Smoking initiation in the birth cohorts (born in 1961 or later) which were in critical age as regards the risk of smoking initiation when the TCA came into force was less common than could be expected according to the trends seen in the earlier birth cohorts. Marked socioeconomic differences were found in smoking in the different birth cohorts. Smoking was more prevalent in the lower socioeconomic groups than in the higher ones, and the differences were larger in the later birth cohorts compared to the earlier ones. The differences between the birth cohorts in ever daily smoking were compatible with the hypothetical impact of the TCA in almost all socioeconomic groups, except farmers. Among men the 1976 TCA appears to have had the greatest impact on white-collar employees. Among women the effect of the act was highly significant in all socioeconomic groups. However, female smoking prevalence continues to show wide socioeconomic disparities. Daily smoking decreased among employees after the 1995 TCAA, supporting the hypothesis of the lowering impact of the amendment on daily smoking due to increased smoking cessation. No parallel change in daily smoking was found in the population without direct expose to ETS legislation (farmers, students, housewives, pensioners or unemployed). Exposure to ETS decreased markedly among non-smokers at work after the 1995 TCAA. The 1976 TCA and the 1995 TCAA were useful in controlling smoking initiation and cessation, but their impact was not equal across the population groups. The results of this study strongly suggested that tobacco control policies markedly contribute to the decrease in smoking and in exposure to environmental tobacco smoke.

Development of analytical techniques for studies on dispersion of actinides in the environment and characterization of environmental radioactive particles

Radioactive particles from three locations were investigated for elemental composition, oxidation states of matrix elements, and origin. Instrumental techniques applied to the task were scanning electron microscopy, X-ray and gamma-ray spectrometry, secondary ion mass spectrometry, and synchrotron radiation based microanalytical techniques comprising X-ray fluorescence spectrometry, X-ray fluorescence tomography, and X-ray absorption near-edge structure spectroscopy. Uranium-containing low activity particles collected from Irish Sea sediments were characterized in terms of composition and distribution of matrix elements and the oxidation states of uranium. Indications of the origin were obtained from the intensity ratios and the presence of thorium, uranium, and plutonium. Uranium in the particles was found to exist mostly as U(IV). Studies on plutonium particles from Runit Island (Marshall Islands) soil indicated that the samples were weapon fuel fragments originating from two separate detonations: a safety test and a low-yield test. The plutonium in the particles was found to be of similar age. The distribution and oxidation states of uranium and plutonium in the matrix of weapon fuel particles from Thule (Greenland) sediments were investigated. The variations in intensity ratios observed with different techniques indicated more than one origin. Uranium in particle matrixes was mostly U(IV), but plutonium existed in some particles mainly as Pu(IV), and in others mainly as oxidized Pu(VI). The results demonstrated that the various techniques were effectively applied in the characterization of environmental radioactive particles. An on-line method was developed for separating americium from environmental samples. The procedure utilizes extraction chromatography to separate americium from light lanthanides, and cation exchange to concentrate americium before the final separation in an ion chromatography column. The separated radiochemically pure americium fraction is measured by alpha spectrometry. The method was tested with certified sediment and soil samples and found to be applicable for the analysis of environmental samples containing a wide range of Am-241 activity. Proceeding from the on-line method developed for americium, a method was also developed for separating plutonium and americium. Plutonium is reduced to Pu(III), and separated together with Am(III) throughout the procedure. Pu(III) and Am(III) are eluted from the ion chromatography column as anionic dipicolinate and oxalate complexes, respectively, and measured by alpha spectrometry.

Development of analytical methods for the separation of plutonium, americium, curium and neptunium from environmental samples

In this work, separation methods have been developed for the analysis of anthropogenic transuranium elements plutonium, americium, curium and neptunium from environmental samples contaminated by global nuclear weapons testing and the Chernobyl accident. The analytical methods utilized in this study are based on extraction chromatography. Highly varying atmospheric plutonium isotope concentrations and activity ratios were found at both Kurchatov (Kazakhstan), near the former Semipalatinsk test site, and Sodankyl�� (Finland). The origin of plutonium is almost impossible to identify at Kurchatov, since hundreds of nuclear tests were performed at the Semipalatinsk test site. In Sodankyl��, plutonium in the surface air originated from nuclear weapons testing, conducted mostly by USSR and USA before the sampling year 1963. The variation in americium, curium and neptunium concentrations was great as well in peat samples collected in southern and central Finland in 1986 immediately after the Chernobyl accident. The main source of transuranium contamination in peats was from global nuclear test fallout, although there are wide regional differences in the fraction of Chernobyl-originated activity (of the total activity) for americium, curium and neptunium.