Mobilization of natural uranium series radionuclides at three mining sites in Finland

Northern Fennoscandia has experienced an unparalleled mineral exploration boom since around 2005. At the same time, there has been increasing awareness of the potential environmental impact of non-nuclear industries that extract and/or process ores containing naturally occurring radionuclides. Industrial activities may result in significant environmental problems if the waste generated during ore processing is not adequately managed. In 2010, a new project was launched with an objective to study the mobility of uranium series radionuclides from diverse mill tailings in a northern boreal environment in Finland. Three sites were investigated: the Talvivaara Ni-Cu-Zn-Co mine in central Finland, a former phosphate mine at Sokli, Finnish Lapland, and a former pilot-scale uranium mine at Paukkajanvaara, eastern Finland. The mobility of radionuclides from the mill tailings at Sokli was examined in order to assess the potential environmental impact of past and future mining activities. Mineralogical studies did not indicate that uranium or thorium have been mobilized from altered pyrochlore-group minerals in the Sokli ore or tailings. In the tailings pond, no clear trends were observed in the activity concentrations of uranium, radium or thorium isotopes in the surface layers of the mill tailings. In subsurface samples, an increase in the concentration of these isotopes can be seen when approaching the pond at the distal end of the sludge field. However, this increase is most likely to a consequence of compositional changes in material discharges. The results of the sequential extraction tests suggested that neither uranium nor thorium is in an exchangeable form and could potentially be released to the environment. Uranium (4% of the total concentration) was partly soluble under weakly acidic conditions, whereas thorium was tightly bound in mineral phases. At the former Paukkajanvaara uranium mine in Eno, the aim of the study was to examine the potential for further mobilization of radionuclides after remediation of the site in early 1990s. There are two primary sources of contamination at the site, the waste rock pile and the tailings. The results indicate that Ra-226 has been leached from the waste rock pile and accumulated in surrounding soil. In run-off sediment samples collected from a dry stream bed near the waste rock pile, the activity concentrations of Ra-226 and U-238 are higher than in soil samples. From the tailings, radionuclides can leach directly to the lake and to another small stream, which flows to the east of the waste rock pile. The results from the soil samples collected between the tailings area and the stream indicate leaching of U-238 and Ra-226 with the surface flow. Sediment samples collected from the bottom of the lake display pronounced uranium series disequilibrium with fractionation of Pb-210 and Ra-226 relative to the parent U-238. The results therefore indicate that leaching and accumulation of at least Ra-226 from the waste rock pile and possibly tailings is still ongoing. At Talvivaara, the aim of the study was to generate new data leading to a better understanding of the fate of radiotoxic uranium daughter nuclides, primarily Ra-226, Pb-210 and Po-210, in the mining process. In heap leaching, uranium is dissolved from uraninite to the pregnant leach solution. Uranium is probably transported as uranyl ions and uranyl sulfate complexes in the acid pregnant leach solution (PLS), and finally ends up in precipitates of the gypsum pond tailings via iron removal and final neutralization processes during the removal of residual metals. In terms of radiation safety, the U-238 activity concentration in the gypsum pond is partly above the exemption value (1000 Bq/kg) for natural radionuclides of the U-238 series. Radium and thorium mostly stay in the heaps during heap leaching. In addition, Pb-210 and Po-210 stay mainly in the heaps but slight mobilization of these nuclides was indicated. Secondary sulfate minerals, such as gypsum and jarosite, are precipitated from the sulfate-rich and acid PLS at Talvivaara. These minerals can incorporate radium in their crystal lattices, limiting Ra-226 mobility. Therefore, it can be assumed that most of radium and possibly part of Pb-210 and Po-210 are co-precipitated with poorly soluble sulfates in the Talvivaara heaps.Pohjoisessa Fennoskandiassa kaivostoiminta on ollut kasvussa vuodessa 2005 lähtien. Samanaikaisesti on tiedostettu, että malmin louhinta ja prosessointi voivat johtaa vakaviin ympäristöongelmiin, mikäli syntynyttä kaivosjätettä ei käsitellä asianmukaisesti. Vuonna 2010 Helsingin yliopiston Radiokemian laboratorio yhteistyökumppaneineen käynnisti Suomen Akatemian rahoittaman nelivuotisen projektin, jonka tarkoituksena oli tutkia uraanisarjan radionuklidien mobilisaatiota erilaisista kaivosjätteistä Suomen pohjoisboreaalisessa ympäristössä. Tutkimuskohteina olivat entinen uraanikaivos Paukkajanvaarassa Enossa, entinen fosfaattikaivos Soklissa Itä-Lapissa, sekä Talvivaaran Ni-Cu-Zn-Co-kaivos Sotkamossa. Paukkajanvaaran entisen uraanikaivoksen tutkimuksessa pyrittiin selvittämään radionuklidien liukoisuutta 1990-luvun alkuvuosien kunnostuksen jälkeen. Alueella on kaksi ensisijaista kontaminaatiolähdettä: raakkukasa ja jätekenttä. Tulokset osoittivat, että 226Ra on liuennut raakkukasasta ja kertynyt ympäröivään maaperään. Raakkukasan läheisyydestä kerätyissä kuivuneen puronuoman sedimenttinäytteissä 226Ra ja 238U-konsentraatiot olivat maaperänäytteitäkin suuremmat. Jätekentästä radionuklidit saattavat huuhtoutua pieneen järveen tai puroon, joka kulkee kentän vieressä ja laskee järveen. Jätekentän ja puron välistä kerättyjen maaperänäytteiden tulokset osoittivat, että 226Ra ja 238U huuhtoutuu pintavalunnan mukana. Järven pohjasta kerätyissä sedimenttinäytteissä oli havaittavissa 210Pb -ja 226Ra-nuklidien fraktioitumista 238U nähden. Näin ollen tulosten perusteella ainakin 226Ra-nuklidin huuhtoutuminen raakkukasasta ja mahdollisesti rikastushiekkakentältä sekä kertyminen ympäristöön jatkuu edelleen. Soklissa radionuklidien mobilisaatiota kaivosjätteestä tutkittiin tarkoituksena selvittää aiemman ja tulevan kaivostoiminnan mahdollisia ympäristövaikutuksia. Mineralogiset tutkimukset eivät osoittaneet, että uraania tai toriumia olisi mobilisoitunut malmista tai kaivosjätteestä. Jätekentän päällimmäisen kerroksen näytteissä ei havaittu selkeää eroavaisuutta uraanin, radiumin ja toriumin aktiivisuuskonsentraatioiden välillä. Alemman kerroksen näytteissä näiden isotooppien konsentraatiot suurenevat jätekentän toisessa päässä olevaa lampea kohden. Konsentraatioiden suureneminen johtuu kuitenkin todennäköisesti jätepäästöjen koostumuksen vaihteluista. Selektiiviset uuttokokeet lisäksi osoittivat, ettei uraani eikä torium esiinny vaihtuvassa muodossa näytteissä ja näin ollen ne eivät vapaudu liuokseen helposti. Uraani (4 % kokonaiskonsentraatiosta) oli osittain liukenevassa muodossa heikosti happamissa olosuhteissa. Sen sijaan torium oli edelleen tiukasti kiinni mineraalifaaseissaan. Talvivaaran tutkimuksen tarkoituksena oli selvittää radiotoksisten uraanin tytärnuklidien 226Ra, 210Pb ja 210Po käyttäytymistä kaivosprosessissa. Biokasaliuotuksessa uraani liukenee uraniniitista prosessiliuokseen ja päätyy lopulta kipsisakka-altaaseen. Säteilysuojelun näkökulmasta 238U-aktiivisuuskonsentraatio ylittää osittain altaassa 238U-sarjan radionuklidien vapaarajan (1000 Bq/kg). Radium ja torium jäävät suurelta osin liuotuskasaan. Myös 210Pb ja 210Po jäävät kasoihin, joskin pientä liukenemista havaittiin. Sekundaariset mineraalit, kuten kipsi ja jarosiitti, saostuvat sulfaatteja sisältävästä happamasta prosessiliuoksesta ja sitovat radiumia kidehiloihinsa rajoittaen näin sen liikkumista prosessissa. Samoin 210Pb ja 210Po kerasaostuvat pääsääntöisesti vähäliukoisten sulfaattimineraalien kanssa Talvivaaran bioliuotuskasoissa

Behaviour of Metals during Bioheap Leaching at the Talvivaara Mine, Finland

The behaviour of base metals Ni, Zn, Cu, Co, Fe, and Mn, potentially toxic metals Pb, Cr, and Cd, and the radioactive elements, U and Th, in the Talvivaara mining process, Finland has been studied by tracing metal concentrations from the black schist ore, through ores subjected to bioheap leaching of varying duration, to pregnant leach solution (PLS), and solid process waste material deposited on site in gypsum waste ponds. It is apparent that Zn, Cu, Co, and Cd are leached from the ore in a similar manner and recovered efficiently in the PLS; however, Ni, though leached, was also found in the gypsum pond at relatively high concentrations. Relatively little Pb is released from the ore, but the small fraction that is mobilised accumulates in the gypsum pond. Of the radioactive constituents, Th is essentially immobile, whereas U is readily leached from the ore, again accumulating in gypsum pond waste. In addition, a laboratory-based sequential leach test was applied to assess the future leaching potential of metals from residual ore and process waste material under different environmental conditions.Peer reviewe

Radionuclide and heavy metal redistribution at the former pilot-scale apatite plant in Sokli, northern Finland

A new phosphate mine is being planned at Sokli in northern Finland. In the late 1970s, pilot-scale mining and mineral processing took place at the site. The mobilisation of radionuclides and heavy metals from the mill tailings was examined in order to assess the potential environmental impact of past and future mining activities. Given the considerable amount of apatite still present, the waste material does not represent true tailings. Variations in abundance probably represent material discharges to the tailings rather than mobilization of the elements from the tailings themselves. No indication of heavy-metal migration was found. Extraction results suggest that only a small proportion of cadmium is in exchangeable form. Elements that are partly soluble under weakly-acidic conditions include copper, zinc, cadmium, uranium and lead. However, most of the elements are tightly bound to the sample matrix and therefore not easily released to the environment.Peer reviewe

Release of base and potentially harmful metals from waste deposits at a former uranium mine in eastern Finland

Peer reviewe

The Plot Thickens: Haploid and Triploid-Like Thalli, Hybridization, and Biased Mating Type Ratios in Letharia

The study of the reproductive biology of lichen fungal symbionts has been traditionally challenging due to their complex lifestyles. Against the common belief of haploidy, a recent genomic study found a triploid-like signal in Letharia. Here, we infer the genome organization and reproduction in Letharia by analyzing genomic data from a pure culture and from thalli, and performing a PCR survey of the MAT locus in natural populations. We found that the read count variation in the four Letharia specimens, including the pure culture derived from a single sexual spore of L. lupina, is consistent with haploidy. By contrast, the L. lupina read counts from a thallus' metagenome are triploid-like. Characterization of the mating-type locus revealed a conserved heterothallic configuration across the genus, along with auxiliary genes that we identified. We found that the mating-type distributions are balanced in North America for L. vulpina and L. lupina, suggesting widespread sexual reproduction, but highly skewed in Europe for L. vulpina, consistent with predominant asexuality. Taken together, we propose that Letharia fungi are heterothallic and typically haploid, and provide evidence that triploid-like individuals are hybrids between L. lupina and an unknown Letharia lineage, reconciling classic systematic and genetic studies with recent genomic observations

Weight concerns as a predictor of smoking cessation according to nicotine dependence : A population-based study

Background: Nicotine-dependent smokers find it difficult to quit smoking. Additionally, smoking-specific weight concerns may affect smoking cessation although the evidence is controversial. We investigated whether smoking-specific weight concerns predict the probability of cessation and, if so, whether the effect varies according to the level of nicotine dependence. Methods: The study was conducted with a population-based sample of 355 adult daily smokers who participated in the baseline examination in 2007 and in the 2014 follow-up. Baseline nicotine dependence was classified as low or high (Fagerstrom Test for Nicotine Dependence; 0-3 vs. 4-10 points). Within these groups, we examined whether baseline weight concerns predict smoking status (daily, occasional, ex-smoker) at follow-up by using multinomial logistic regression with adjustment for multiple covariates. Results: Among low-dependent participants at baseline, 28.5% had quit smoking, while among highly dependent participants 26.1% had quit smoking. The interaction between weight concerns and nicotine dependence on follow-up smoking status was significant. Among participants with low nicotine dependence per the fully adjusted model, greater weight concerns predicted a lower likelihood of both smoking cessation (relative risk ratio 0.93 [95% CI 0.87-1.00]) and smoking reduction to occasional occurrence (0.89 [95% CI 0.81-0.98]). Weight concerns were not associated with follow-up smoking status among participants with high nicotine dependence. Conclusions: Weight concerns are associated with a smaller likelihood of quitting among smokers with low nicotine dependence. Weight concerns should be addressed in smoking cessation interventions, especially with smokers who have low nicotine dependence.Peer reviewe

Continuous Experimentation Cookbook : An introduction to systematic experimentation for software-intensive businesses

An increasing number of companies are involved in building software-intensive products and services – hence the popular slogan “every business is a software business”. Software allows companies to disrupt existing markets because of its flexibility. This creates highly dynamic and competitive environments, imposing high risks to businesses. One risk is that the product or service is of only little or no value to customers, meaning the effort to develop it is wasted. In order to reduce such risks, you can adopt an experimentdriven development approach where you validate your product ideas before spending resources on fully developing them. Experiments allow you to test assumptions about what customers really want and react if the assumptions are wrong. This book provides an introduction to continuous experimentation, which is a systematic way to continuously test your product or service value and whether your business strategy is working. With real case examples from Ericsson, Solita, Vaadin, and Bittium, the book not only gives you the concepts needed to start performing continuous experimentation, but also shows you how others have been doing it

Release of radionuclides from waste rock and tailings at a former pilot uranium mine in eastern Finland

The Paukkajanvaara mine in Eno, eastern Finland, started to operate in 1959. The mine was a test site for assessing the feasibility of larger-scale uranium extraction. Pilot-scale mining and milling were carried out between 1958 and 1961, and the mine site was rehabilitated in the early 1990s. The aim of this study was to examine the potential for further mobilization of radionuclides after remediation. There are two primary sources of contamination at the site, the waste-rock pile and the tailings. Our study indicates that 226Ra leached from the waste-rock pile and accumulated in surrounding soil. In run-off sediment samples collected from a dry stream bed near the waste-rock pile, the activity concentrations of 226Ra and 238U were higher than in soil samples. From the tailings, radionuclides can leach directly to the lake and to another small stream, which flows to the east of the waste-rock pile. In the water samples collected from this stream, uranium concentrations increased at the outlet to the lake. The results from the soil samples collected between the tailings area and the stream indicate leaching of 238U and 226Ra with the surface flow. Sediment samples collected from the bottom of the lake displayed pronounced uranium series disequilibrium with fractionations of 210Pb and 226Ra relative to the parent 238U. The results therefore indicate that leaching and accumulation of at least 226Ra from the waste-rock pile and possibly tailings is still ongoing.Peer reviewe

Long-term follow up of families with pathogenic NFKB1 variants reveals incomplete penetrance and frequent inflammatory sequelae

Publisher Copyright: © 2022 The AuthorsNuclear factor κ light-chain enhancer of activated B cells (NF-κB) family of evolutionarily conserved transcription factors are involved in key cellular signaling pathways. Previously, hypogammaglobulinemia and common variable immunodeficiency (CVID)-like phenotypes have been associated with NFKB1 variants and loss-of-function NFKB1 variants have been reported as the most common monogenic cause for CVID among Europeans. Here, we describe a Finnish cohort of NFKB1 carriers consisting of 31 living subjects in six different families carrying five distinct heterozygous variants. In contrast to previous reports, the clinical penetrance was not complete even with advancing age and the prevalence of CVID/hypogammaglobulinemia was significantly lower, whereas (auto)inflammatory manifestations were more common (42% of the total cohort). At current stage of knowledge, routine genetic screening of asymptomatic individuals is not recommended, but counseling of potential adult carriers seems necessary.Peer reviewe

Effectiveness of internet-delivered cognitive behavioural therapy in reducing sickness absence among young employees with depressive symptoms : study protocol for a large-scale pragmatic randomised controlled trial

INTRODUCTION: Depression is a highly prevalent condition with typical onset in early adulthood. Internet-delivered cognitive behavioural therapy (iCBT) is a promising cost-effective and more widely available alternative to face-to-face CBT. However, it is not known whether it can reduce sickness absence in employees showing depressive symptoms. The randomised controlled trial component of the DAQI (Depression and sickness absence in young adults: a quasi-experimental trial and web-based treatment intervention) project aims to investigate if iCBT is effective in reducing sickness absence compared with care as usual (CAU) among young employees with depressive symptoms in primary care provided in an occupational health setting. METHODS AND ANALYSIS: This study will use a randomised controlled single-centre service-based trial of an existing iCBT programme (Mental Hub iCBT for Depression) to evaluate whether or not this treatment can reduce the number of sickness absence days in public sector employees aged 18-34 years who present at the occupational health service with mild depressive symptoms (score textgreater/=9 on the Beck Depression Inventory-IA). Control participants will be offered CAU, with no constraints regarding the range of treatments. The active condition will consist of seven weekly modules of iCBT, with support from a web therapist. Primary outcome will be participants' all-cause sickness absence as indicated in employer's and national administrative records up to 6 months from study entry. Secondary outcomes relating to long-term sickness absence (over 11 calendar days) for mental and musculoskeletal disorders and psychotropic medication use will be obtained from the Finnish Social Insurance Institution's administrative records; and short sickness absence spells (up to 11 calendar days) will be extracted from employer's records. Analyses will be conducted on an intention-to-treat basis. ETHICS AND DISSEMINATION: The Coordinating Ethics Committee of the Hospital District of Helsinki and Uusimaa has approved the study (HUS/974/2019). The results will be published in peer-reviewed scientific journals and in publications for lay audience. TRIAL REGISTRATION NUMBER: ISRCTN10877837.Peer reviewe