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Tekstiiliteollisuudessa käytetään merkittäviä määriä kemikaaleja, joista osa on ympäristölle ja terveydelle haitallisia. Tekstiiliteollisuuskehityksen kasvaessa ja kulutuskäytäntöjen kiihtyessä pois heitettävän tekstiilin määrä lisääntyy. Samalla haitalliset kemikaalit vapautuvat saastuttamaan ihmistä ja ympäristöä. Tämä käy ilmi aiemmasta tutkimuksesta, vaikka poistotekstiilien ympärillä tehty tutkimus on muutoin vähäistä. Tämä tutkimus tehdään yritysyhteistyössä Lounais-Suomen Jätehuolto Oy:n kanssa määrittämään poistotekstiilien lajittelutyön yhteydessä ilmeneviä terveysvaikutuksia ja sovellettavia testimenetelmiä yrityksen tarpeisiin. Tutkielman tavoitteena oli ensisijaisesti selvittää kemikaalien, pölyn ja homeen terveysvaikutukset ja ne testimenetelmät, joita tulisi terveysvaikutusten vähentämiseksi tehdä. Muiden tutkimuskysymysten osalta tarkoituksena oli selvittää poistotekstiilien sisältämät merkittävimmät haitalliset kemikaalit ja niiden enimmäisraja-arvot. Näitä tutkittiin tutkimuksen teoreettisessa viitekehyksessä. Tutkimuksessa käytettiin laadullista tutkimussuuntausta ja sen menetelmiä. Aineiston keruumenetelmänä oli asiantuntijahaastattelu, jossa tietoja kerättiin puolistrukturoidun kysymyksenasettelun kautta neljältä asiantuntijataholta: Turun ammattikorkeakoululta, Terveyden- ja hyvinvoinninlaitokselta, Työterveyslaitokselta ja Aalto-yliopistolta. Haastattelut toteutettiin puhelinhaastatteluina. Aineistoa analysoitiin temaattisen sisällönanalyysin avulla, jossa aineisto luokiteltiin tutkimuksen kannalta merkittävimpiin teemoihin. Saatuja tuloksia verrattiin olemassa olevaan tutkimuskirjallisuuteen. Hengitystievälitteinen altistuminen yksistään pölylle nähtiin merkittävimmäksi terveysriskiksi laitosolosuhteissa. Kemikaalien, pölyn ja homeen aiheuttamien terveysvaikutusten vähentämiseksi soveltuvimpina testimenetelminä nähtiin erilaisten keräävien menetelmien käyttö ja biomonitorointi. On selvää, että poistotekstiilit sisältävät ihmisen terveydelle ja ympäristölle haitallisia kemikaaleja, pölyä ja homeita. Testimenetelmiä hyödyntämällä voidaan terveysriskejä paikantaa ja niiden osuutta työperäisessä altistumisessa vähentää. Tutkimustulosten tieteellisen luotettavuuden lisäämiseksi on suositeltavaa, että laitoksella otetaan käyttöön kokeelliset testausmenetelmät.

In reductive dehalogenation, halogenated compounds act as electron acceptors in respiration or cometabolic reactions. The halogen atom is removed and usually replaced with hydrogen. Polybrominated diphenyl ethers (PBDEs) are persistent and toxic compounds, which have been extensively used as flame retardants. Even after bans and use restrictions, they are released to the environment from products manufactured earlier. PBDEs have been found ubiquitously in the environment. In anaerobic conditions like in sediments, they can be degraded through reductive dehalogenation. While remediating contaminated sediments, knowledge is needed about factors affecting the degradation of PBDEs. In the present work, anaerobic debromination of two PBDEs, BDE-47 and BDE-209 in sediment was investigated in microcosms. Sediment samples were taken from the estuary of the Kymijoki River from the Baltic, and from two sites in Lake Kernaalanjärvi, one representing clean and the other contaminated sediment. In addition to sampling site, the effect of incubation temperature on the degradation rate and products was investigated with different treatments, and possible abiotic degradation was examined with autoclaved controls. The samples were analyzed with gas chromatograph with electron capture detector (GC-µECD). The amounts of Dehalococcoides and total bacteria as 16S rRNA gene copies were determined with qPCR. Hypotheses were that debromination is faster in contaminated sediments, in warmer temperature, and in the microcosms with more bacteria of the genus Dehalococcoides. The half-time of BDE-47 varied from 173 to 7701 weeks, and that of BDE-209 from 28 to 173 weeks. The debromination rate could not be explained with sampling sites or incubation temperature, but the degradation of BDE-47 was significantly slower in autoclaved microcosms. In the microcosms where BDE-47 was removed most, the main debromination product was BDE-8. In the microcosms with sediment from the clean site of Lake Kernaalanjärvi, the amount of BDE-47 did not decrease. Obviously, bacteria capable of degrading it are not abundant in sites with little or no previous contamination with organohalogens. The removal of BDE-209 in autoclaved microcosms is probably explained with abiotic degradation or adsorption so that the compound is not extractable. At the end of incubation, there were more total bacteria in the microcosms with BDE-47 than those with BDE-209. The proportion of Dehalococcoides was greater in the microcosms with BDE-209, those incubated in room temperature, and those not autoclaved. Debromination was faster in the microcosms with more total bacteria in the beginning or Dehalococcoides at the end. BDE-47 proved to be more persistent than in the literature reviewed. The hypotheses about the effect of the incubation temperature and the contamination of the sediment did not reach statistical significance, but the importance of Dehalococcoides for debromination was established according to the hypothesis.

Ihmistoiminta muuttaa elinympäristöjä maailmanlaajuisesti. Vaikutukset näkyvät niin yksittäisten lajien populaatioissa, lajien välisissä vuorovaikutuksissa kuin kokonaisten ekosysteemien toiminnassakin. Monimutkaisuutensa ja vaikean havainnoitavuutensa takia lajien väliset vuorovaikutukset ja erityisesti niiden yhteys ekosysteemien toimintaan tunnetaan osin huonosti. Ympäristömuutoksista ilmaston lämpeneminen vaikuttaa erityisen voimakkaasti arktisella alueella. Muuttuva ja yksinkertainen arktinen eliöyhteisö tarjoaakin loistavan malliekosysteemin lajien välisten vuorovaikutusten havainnoimiselle ja niiden rakenteen mallintamiselle. Tässä tutkielmassa selvitän pölyttäjäyhteisön rakennetta ja toimintaa yhden kasvilajin, lapinvuokon Dryas octopetala × integrifolia, pölytyksessä. Lapinvuokko on runsain kukkakasvi monilla pohjoisilla alueilla, ja sitä voidaankin pitää avainlajina paikallisissa pölytysyhteisöissä. Liittääkseni pölyttäjäyhteisön rakenteen lapinvuokon siementuotannon onnistumiseen havainnoin lapinvuokon pölyttäjäyhteisön vaihtelua tilassa ja ajassa. Tähän käytin kukanmuotoisia liimapahvista valmistettuja pyydyksiä. Tein liimakukkapyyntejä 21 koealalla Zackenbergin laaksossa Grönlannissa. Tutkin koealoilla lisäksi lapinvuokon siementuotantoa. Tutkimuksessani havaitsin, että lapinvuokon kukinnan ajoittumisessa on suurta alueellista vaihtelua. Ensimmäiset kukat puhkeavat heti pälvien ilmestyessä ja viimeisten yksilöiden kukinta alkaa vasta juuri ennen ensilumia. Myös lapinvuokon siementuotannon onnistuminen vaihtelee paljon (12,7 - 52,7 % kukista) alueellisesti. Alueellinen vaihtelu siementuotannon onnistumisessa johtuu osittain ympäristöolosuhteista, mutta myös pölyttäjäyhteisöllä on selvä vaikutuksensa. Lapinvuokolla tapahtuu itse- ja tuulipölytystä (8,6 % onnistuneesta siementuotannosta), mutta pölyttäjien läsnä ollessa siementuotanto on moninkertainen (33,7 %). Tutkimusalueellani Zackenbergissa maailmanlaajuisesti tärkeimmät pölyttäjät, mesipistiäiset, puuttuvat lähes tyystin. Runsaimpien pölyttäjien paikan ovat vallanneet kärpäset erityisen runsaslukuisten sukaskärpästen johdolla. Havaintojeni perusteella sukaskärpästen runsaus selittääkin parhaiten lapinvuokon siementuotannon onnistumista. Kesän edetessä havaitsin pölyttäjäyhteisön kasvavan huomattavasti sekä yksilö- että lajimäärältään. Pölyttäjäyhteisön runsastuminen kasvukauden edetessä antaa olettaa, että lapinvuokon pölytys voi parantua ainakin lyhyellä aikavälillä. Ilmaston lämmetessä pölyttäjien esiintymisen on havaittu liukuvan aikaisemmaksi kasvien kukintaa nopeammin. Näin ollen aikaisin kukkivat kasvit kohtaavat yhä enemmän pölyttäjiä ja myöhäisimmätkin kasvit onnistuvat tuottamaan siemeniä ennen syksyä, kun niiden kukinta siirtyy absoluuttisesti aikaisemmaksi. Toisaalta sukaskärpästen määrän on havaittu vähenevän ilmaston lämmetessä. Tutkimukseni pohjalta sukaskärpäset ovat lapinvuokon tärkeimpiä pölyttäjiä, ja jos niiden väheneminen jatkuu, on lapinvuokon pölytys Zackenbergissa uhattuna. Kaiken kaikkiaan tutkimukseni viittaa siihen, että lapinvuokon pölytys voi lyhyellä aikavälillä parantua, mutta pitkällä aikavälillä muutokset pölyttäjäyhteisössä uhkaavat lapinvuokon pölytyksen onnistumista. Lapinvuokko on arktisen alueen tärkeimpiä kasveja niin pölyttäjien kuin monien muidenkin hyönteisten ravintona. Siten muutokset sen menestyksessä heijastunevat koko pölyttäjien ja kukkakasvien muodostamaan yhteisöön.

Gliomas are the most common malignant brain tumours. The most aggressive and lethal type of glioma is glioblastoma. It has a dismal prognosis, and, despite aggressive treatment, the average patient survival is 1-2 years. Although glioblastoma has a heavy impact on individuals and their families, as well as on healthcare systems, our current lack of mechanistic knowledge hinders the development of improved treatments and diagnostics. Recent studies showed that glutaminolysis, a metabolic pathway utilizing glutamine to produce α-ketoglutarate, is promoted in tumour cells, suggesting a significant role of α-ketoglutarate concentration in tumour progression. Therefore, I hypothesise that reduction of α-ketoglutarate concentration in glioblastoma might suppress glioblastoma aggressiveness. To address this hypothesis, I focus on another metabolic pathway controlling α-ketoglutarate concentration, namely the GABA metabolism. Here, I show that the expression of ABAT and GAD1, which encode rate-limiting enzymes of the GABA metabolism, is associated with the lower-grade of glioma and a better prognosis for patients. Interestingly the expression of ABAT and GAD1 negatively correlates with the expression of CD109, a glioma stemness marker. Furthermore, suppression of glioblastoma stemness by CD109 silencing induces ABAT and GAD1 expression. Taken together these results suggest that the upregulation of the GABA metabolism reduces glioblastoma stemness and proliferation. In future, I am planning to examine the effect of ABAT and GAD1 overexpression and knockdown on glioblastoma stemness and proliferation, as well as the underlying molecular mechanisms to understand how the GABA metabolism suppresses the glioblastoma progression.

Mitochondrial dysfunction is involved in many neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD). Most of the mitochondrial disorders lack effective treatments so far. One of the important defects of mitochondrial dysfunction is the blockade of mitochondrial respiratory chain. An alternative oxidase (AOX), originated from Ciona intestinalis, has been found to counteract this defect by providing a bypath of the mitochondrial respiratory chain in plants, drosophila, mice and human cultured cells. Therefore, we suggest that AOX might be a promising tool for curing neurodegenerative diseases from the aspect of alleviating mitochondrial defects. An engineered mouse model has been created to express the Ciona intestinalis AOX ubiquitously in the whole animal. Our study aims at investigating the expression and function of AOX in the transgenic mouse brain and exploring therapeutic potential of AOX in human diseases. AFG3l2 gene encodes a subunit of m-AAA metalloprotease, which is involved in mitochondrial protein quality control process. Mutations in the AFG3L2 is known to be related to spinocerebellar ataxias 28 (SCA28), a neurodegenerative disease resulting from cerebellar damage. Loss of AFG3L2 gene causes OPA1 protein cleavage and mitochondrial fragmentation which are easily detected. Thus, we propose an in vitro neurodegenerative disease model generated by knocking down of AFG3L2 in target cells. We used western blotting to detect the expression level of AOX in the brain and primary neuro-glia cells of the transgenic mice, finding that the AOX protein reduces in the brain along with age. Antimycin A treatment on neuro-glia cells demonstrated the function of AOX in transgenic pups. However, the respiratory activity caused by AOX also decreases with the mice age. In addition, we constructed a lentiviral vector with DNA recombinant technology to express AOX in U2OS cells. To examine the function of AOX under disease condition, we established an in vitro neurodegenerative disease model by knocking down the AFG3L2 gene of U2OS cells with siRNA, and infected the cells with AOX lentivirus. By comparing the immunostaining images of wild-type and AOX infected cells, we saw a significant difference in the degree of mitochondrial fragmentation between these cells. Nevertheless, the cleavage pattern of OPA1 protein, which is mainly responsible for mitochondrial fragmentation, remains unchanged whether AOX is present in the cell or not. In conclusion, our study first investigated the expression and function of AOX in the brain of this transgenic mouse model. And we established a lentivirus vector to apply AOX gene to human cells, testing the therapeutic function of AOX in a neurodegenerative disease model in vitro. Moreover, the mitochondrial fragmentation of the disease model is alleviated by AOX despite of OPA1 cleavage, indicating that the mitochondrial phenotype caused by loss of AFG3L2 is not only due to OPA1 cleavage, but also related to respiratory defects. This highlights the possibility to rescue the mitochondrial morphological changes from new aspects.

Paleoekologia tutkii fossiloituneita kasveja ja eläimiä ja niiden suhdetta ympäristöönsä. Se on yksi niistä tutkimusaloista, joka pyrkii selvittämään kuinka esimerkiksi nisäkäsyhteisöjen rakenne on muuttunut aikojen kuluessa ympäristön ja muiden pitkäaikaisten muutosten seuraksena. Tämän tutkimuksen tavoitteena oli selvittää, voidaanko kehittää menetelmä, joka voisi muutamalla nisäkkäisiin liittyvällä perusmuuttujalla, kuten niiden liikkumistavalla ja ravinnolla, määrittää nisäkäslajien muodostaman yhteisön rakenne sekä sen, ovatko nämä rakenteet erilaisia eri elinympäristöjen kesken. Mikäli menetelmä toimisi nykyisten nisäkäslajien tiedoilla, voisi sitä kehittää myös paleoympäristöjen ennustamiseen. Tutkimukseen valittiin kaksi menetelmää nisäkäsyhteisöjen muodostamiseksi. Ensimmäinen menetelmä pohjautui itseorganisoituvaan kartta-algoritmiin (SOM, Self-Organizing Map). Toinen perustui nisäkkäiden ryhmittelyyn liikkumismuodon ja ravinnon perusteella. Kaikki tutkimukseen valitut muuttujat olivat sellaisia, että niitä voidaan käyttää myös paleontologisissa aineistoissa. Ensimmäisen menetelmän tuloksena voidaan todeta, että itseohjautuvan kartan käyttö nisäkäsyhteisöjen muodostamiseen ei ollut toimiva. Muodostuneet yhteisörakenteet olivat hyvin abstrakteja ja niitä oli vaikea selittää. Itseohjautuvien karttojen käyttö soveltui kuitenkin muiden rakenteiden, kuten nisäkkäiden ravintoryhmien luokitteluun. Toisen menetelmän tulokset osoittavat, että on mahdollista erottaa suurin osa maalla olevista pääelinympäristöistä niillä nisäkäsyhteisöjen rakenteilla, jotka muodostettiin lajien liikkumismuodolla ja ravinnolla. Näillä kahdella muuttujalla muodostui merkitseviä eroja eri nisäkäsyhteisöjen välillä. Nämä yhteisöt toimivat hyvin myös eri pääelinympäristöjen indikaattoreina. Osoittautui, että useassa tapauksessa alueilla, joilla oli samankaltaiset ympäristöolot, vaikka sijaitsivatkit eri mantereilla, oli samankaltaiset nisäkäsyhteisöt. Jälkimmäistä menetelmää voidaan kehittää edelleen ryhmittelemällä nisäkäsyhteisöjä myös muiden muuttujien avulla. Näitä muuttujia voisivat olla esimerkiksi nisäkkäiden koko sekä hampaiden rakenne. Kehittämällä algoritmeja, jotka laskevat erikseen elinympäristöjen indikaattoreita ja myöhemmin yhdistävät niitä voisi muodostaa vielä tarkemman mallin elinympäristöjen ennustamiseen.

As a result of habitat degradation, prey depletion, and human-wildlife conflict, African lion (Panther leo) population has been decreasing rapidly in the past decades. Via top-down regulation, lions maintain trophic balance by controlling herbivore populations, and consequently affecting vegetation. Due to their important role in ecosystems, reintroducing lions to small, fenced reserves has become an increasingly important tool in biodiversity conservation and ecosystem restoration, especially in South Africa. However, introducing lions into small systems can negatively affect prey populations as well as smaller carnivores if lion populations are not actively managed, and these impacts can vary depending on prey selection of introduced lions. Prey selection of lions provide valuable information for managers, but currently the knowledge of the impacts of population management on the diet of lions is very limited. Therefore, with this study I was aiming to investigate the influence of sex and management interventions, such as lion removals and introductions, and group size control on the prey preferences of lions in a small, fenced reserve. The study was conducted by using long-term data from the past 30 years on the lion population in the Munywana Conservancy in South Africa. In particular, I used the data on lions’ diet and their history (including management interventions and group sizes), and data on prey abundances. First, I used Jacob’s index to determine prey preferences and specific prey selection of Munywana’s lions in general, per lion unit per year, as well as per sex and lion unit size. Eight main prey species (nyala, warthog, giraffe, wildebeest, impala, kudu, zebra, buffalo) of lions in Munywana were considered in this study. To evaluate the influence of management interventions, group size, and sex on the prey preferences of lions, I used generalized linear mixed models with zero-inflated beta-regression at the level of whole Munywana and at the level of lion unit. Lastly, I used chi-square test to evaluate the impact of lion origin by comparing the diets of introduced and native lions, and to determine whether population management has longer term impacts on prey selection by comparing within lion unit variation in prey selection across years. It was observed that lions are not opportunistic feeders, and they had overall strong prey preferences: some prey species were fed upon more often than others regardless of the abundance of the available prey species. The most preferred prey species in Munywana were warthog and wildebeest, followed by giraffe and zebra, while impala, nyala, and buffalo were generally avoided. The results of this study showed that lion management interventions and lion origin have independent impacts on prey preferences even when sex and group size were accounted for. Introduction of new lions resulted in higher preference for wildebeest and zebra, and lower preference for warthog and nyala, while introduced lions preferred kudu, giraffe, buffalo, and wildebeest significantly more compared to native lions. Sex and group size also had an impact on prey selection: the preference for zebra increased as group size increased, and male lions preferred giraffe, warthog and nyala more compared to female lions, and the removal of male lions resulted in decreased preference for zebra and giraffe. The results of my study supported hypotheses that lion management interventions, lion origin, group size, and sex have an impact on prey selection, but the most significant factors differed between prey species. In addition, the interaction between management interventions, and sex, and their impact on population characteristics of lions appeared to be extremely important, but due to limitations in the data, the relationship between lion translocations, changes in group compositions, and their results in prey choices could not be assessed in a required detail, highlighting the importance for further investigations. My findings reflect the importance of taking prey selection of the apex predator into consideration when planning management interventions and reintroduction projects since it has a potential to substantially alter prey populations, and indirectly vegetation. However, prey selection is a complex process consisting of several factors and their interactions, and therefore further research would be required to enhance our understanding of this process. Management of lion populations is essential in small, fenced reserves, and wider understanding of the impacts of management interventions on the prey preferences would allow conservationists to create better management plans and ensure effective predator conservation as well as the long-term sustainability of predator-prey systems.

In multicellular organisms, complex signalling mechanisms have evolved to guide the behaviour of individual cells. Growth factors are secreted proteins that can stimulate the proliferation and/or differentiation of cells. Vascular endothelial growth factor D (VEGF-D) is a ligand for VEGF receptor 2 (VEGFR-2) and for VEGFR-3, which are predominantly expressed on blood vascular endothelial cells and on lymphatic endothelial cells, respectively. Thus VEGF-D can contribute to growth of both blood vessels (angiogenesis) and lymphatic vessels (lymphangiogenesis). Although there have been many reports showing the angiogenic and lymphangiogenic effects of VEGF-D, its physiological role is still largely unknown. Most of these reports are severely hampered by incomplete characterization of the specific form of VEGF-D that was used. During or after secretion, VEGF-D undergoes complicated proteolytic processing. Alternative Nterminal cleavage results in two different fully processed forms, VEGF-D major and VEGF-D minor. Processing significantly increases the activity of VEGF-D towards its receptors. Surprisingly, it is still unknown whether the differential N-terminal cleavage of VEGF-D has any effect on receptor binding activity or on receptor activation. The goal of this study was to produce and purify high quality biologically active VEGF-D which is needed for studying the physiological role of this growth factor. Several different forms of recombinant human VEGF-D were produced using the Drosophila Schneider 2 insect cell system. A bioassay utilizing the Ba/F3 cells expressing chimeric VEGFR/EpoR receptors was used to determine the receptor binding activities of recombinant VEGF-Ds. Two constructs producing biologically active VEGF-Ds were chosen for chromatographic purification (untagged major and his-tagged major forms). During purification, the activity of both VEGF-D forms towards their receptors decreased significantly. In case of the untagged form, this was presumably due to some residual proteolytic activity during purifications. The results might indicate that only the major form is responsible for the activation of VEGFR-3. The fact that no activity of the minor forms was detected when screening the cell supernatants with Ba/F3-VEGFR-3-EpoR-bioassay, supports this explanation. If this explanation can be verified, the role of the alternative N-terminal cleavage becomes obvious: By proteolysis the activity of VEGF-D can be redirected from the lymphatics towards the blood vessels.

The discovery and development of new antifungal drugs has lagged behind the clinical needs for effective treatments of fungal infections. Invasive fungal infections can be challenging to treat and can become life-threatening, particularly for immunosuppressed individuals. Despite the need for new and improved antifungal drugs, the pipeline for antifungal drug development has been relatively slow, with only a few new agents being approved in recent years. Many existing antifungal drugs have toxic side effects, limiting their use and highlighting the need for more targeted and effective therapeutics. The glycosylphosphatidylinositol biosynthesis pathway has been proposed as a potential new target for antifungal drugs. The glycosylphosphatidylinositol (GPI) anchor is a complex glycoconjugate that is attached to many proteins found on the surface of eukaryotic cells. GPI anchored proteins play important roles in various cellular processes, including signaling, cell adhesion, and cell recognition. The biosynthesis of GPI anchors involves multiple enzymatic steps, including the transfer of the GPI anchor to a target protein. Gpi3 is one of the key enzymes involved in the first step of GPI biosynthesis and is the catalytic subunit of the GPI GlcNAc-PI synthesis complex. The naturally occurring molecule Jawsamycin has been shown to selectively inhibit fungal Gpi3 while not interfering with its human ortholog. However, the development and research of Jawsamycin and other potential inhibitors of the GPI synthesis pathway are hampered by the lack of structural data on the proteins involved in the pathway. This thesis aimed to express and purify functionally active Gpi3 as a recombinant fusion protein using the SUMO tag expression system, with the end goal of utilizing the protein for structural studies through crystallography to better understand the function of Jawsamycin. In this thesis, Gpi3 was successfully expressed and purified as a fusion protein. However, enzymatic activity of Gpi3 was not observed, additionally, the purification and stability of the Gpi3 fusion proteins were shown to be problematic and no crystal structure of the protein of interest was acquired. These results indicate that a different approach is needed to gain structural insights into the function and interaction between Gpi3 and Jawsamycin. A likely path forward is the purification of the whole GPI GlcNAc synthesis complex which could give more insights into the organization and function of both Gpi3 and Jawsamycin.

One open question related to microplastics found in seas is the sources and routes of microplastics into seas. In Helsinki about one third of the snow collected from urban areas is dumped directly into the Baltic sea. When snow is collected from an urban area also the possible waste in the snow becomes collected. This is the first study that examines the numerical quantity and the characteristics of waste in urban snow. In order to study waste contained in snow, samples were collected from three different urban areas in Helsinki in February 2016. Snow was collected from Hakaniemen tori, Kullervonkatu in Käpylä and Sörnäisten rantatie. Solid matter in snow samples was divided into particles sized over 4 mm and 0.3–4 mm. Waste particles were visually identified utilizing the morphology of the particles. Material of selected waste particles was analysed using a FTIR spectrometer. Snow samples collected from Käpylä contained more waste by weight and number than samples collected from other areas. Reasons for differences between sampling areas did not become clear in this study. The most common waste in urban snow were particles disengaged from asphalt pavement and road markings, along with paper, plastic and rubber waste. All snow samples contained microplastics. Urban snow contained more microplastics than purified wastewater leaving from Viikinmäki wastewater treatment plant and seawater in the Gulf of Finland. Stormwaters have been identified as a route for microplastics from urban areas into inland waters and seas, and according to this study also dumping of urban snow into seas acts as a route for microplastics. In urban snow road marking and plastic particles were the most common microplastics. In snow samples collected from road areas road marking particles were clearly the most common microplastic by number. In snow collected from Hakaniemen tori about half of the microplastics were plastic particles and almost a half road marking particles. Most of the microplastics in snow were different kinds of fragments. Like in earlier microplastics studies also in urban snow the most common materials of small plastic particles were polyethylene and polypropylene. In this study sources of the waste in snow are estimated to be the abrasion of asphalt pavement, road markings, tyres, plastic products and possibly also wood and metal products and different kinds of textiles. In addition to that numerous waste items had ended up in urban areas through littering or inadequate waste disposal. Littering is the most significant environmental impact of dumping urban snow into the sea in Helsinki. Marine Strategy Framework Directive states that properties and quantities of marine litter are not to cause harm to the coastal and marine environment. According to the guidelines of the City of Helsinki, snow that is brought to snow collection sites needs to be clean and not to contain waste. Nevertheless, according to this study through dumping snow into the sea in Hernesaaren ranta several thousand kilograms of waste and approximately over fifty million microplastic particles end up in the Baltic Sea. A monitoring program should be established to investigate and monitor the amount and the characteristics of waste in urban snow in Helsinki.