14 resultados para Great Plains

em Doria (National Library of Finland DSpace Services) - National Library of Finland, Finland


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The bioavailability of metals and their potential for environmental pollution depends not simply on total concentrations, but is to a great extent determined by their chemical form. Consequently, knowledge of aqueous metal species is essential in investigating potential metal toxicity and mobility. The overall aim of this thesis is, thus, to determine the species of major and trace elements and the size distribution among the different forms (e.g. ions, molecules and mineral particles) in selected metal-enriched Boreal river and estuarine systems by utilising filtration techniques and geochemical modelling. On the basis of the spatial physicochemical patterns found, the fractionation and complexation processes of elements (mainly related to input of humic matter and pH-change) were examined. Dissolved (<1 kDa), colloidal (1 kDa-0.45 μm) and particulate (>0.45 μm) size fractions of sulfate, organic carbon (OC) and 44 metals/metalloids were investigated in the extremely acidic Vörå River system and its estuary in W Finland, and in four river systems in SW Finland (Sirppujoki, Laajoki, Mynäjoki and Paimionjoki), largely affected by soil erosion and acid sulfate (AS) soils. In addition, geochemical modelling was used to predict the formation of free ions and complexes in these investigated waters. One of the most important findings of this study is that the very large amounts of metals known to be released from AS soils (including Al, Ca, Cd, Co, Cu, Mg, Mn, Na, Ni, Si, U and the lanthanoids) occur and can prevail mainly in toxic forms throughout acidic river systems; as free ions and/or sulfate-complexes. This has serious effects on the biota and especially dissolved Al is expected to have acute effects on fish and other organisms, but also other potentially toxic dissolved elements (e.g. Cd, Cu, Mn and Ni) can have fatal effects on the biota in these environments. In upstream areas that are generally relatively forested (higher pH and contents of OC) fewer bioavailable elements (including Al, Cu, Ni and U) may be found due to complexation with the more abundantly occurring colloidal OC. In the rivers in SW Finland total metal concentrations were relatively high, but most of the elements occurred largely in a colloidal or particulate form and even elements expected to be very soluble (Ca, K, Mg, Na and Sr) occurred to a large extent in colloidal form. According to geochemical modelling, these patterns may only to a limited extent be explained by in-stream metal complexation/adsorption. Instead there were strong indications that the high metal concentrations and dominant solid fractions were largely caused by erosion of metal bearing phyllosilicates. A strong influence of AS soils, known to exist in the catchment, could be clearly distinguished in the Sirppujoki River as it had very high concentrations of a metal sequence typical of AS soils in a dissolved form (Ba, Br, Ca, Cd, Co, K, Mg, Mn, Na, Ni, Rb and Sr). In the Paimionjoki River, metal concentrations (including Ba, Cs, Fe, Hf, Pb, Rb, Si, Th, Ti, Tl and V; not typical of AS soils in the area) were high, but it was found that the main cause of this was erosion of metal bearing phyllosilicates and thus these metals occurred dominantly in less toxic colloidal and particulate fractions. In the two nearby rivers (Laajoki and Mynäjoki) there was influence of AS soils, but it was largely masked by eroded phyllosilicates. Consequently, rivers draining clay plains sensitive to erosion, like those in SW Finland, have generally high background metal concentrations due to erosion. Thus, relying on only semi-dissolved (<0.45 μm) concentrations obtained in routine monitoring, or geochemical modelling based on such data, can lead to a great overestimation of the water toxicity in this environment. The potentially toxic elements that are of concern in AS soil areas will ultimately be precipitated in the recipient estuary or sea, where the acidic metalrich river water will gradually be diluted/neutralised with brackish seawater. Along such a rising pH gradient Al, Cu and U will precipitate first together with organic matter closest to the river mouth. Manganese is relatively persistent in solution and, thus, precipitates further down the estuary as Mn oxides together with elements such as Ba, Cd, Co, Cu and Ni. Iron oxides, on the contrary, are not important scavengers of metals in the estuary, they are predicted to be associated only with As and PO4.

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Julkaisussa: Geographia classica : the geography of the ancients

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The National Library of Finland realizes the Digitization Project of Kindred Languages in 2012–15. The project is financially supported by the Kone Foundation. During this project the National Library of Finland has digitized and made available approximately 1200 monograph and more than 100 newspaper titles in several Uralic languages. The materials are available to both researchers and citizens in the National Library’s Fenno-Ugrica collection. The project will produce digitized materials in the Uralic languages as well as their development tools to support linguistic research and citizen science. The resulting materials will constitute the largest resource for the Uralic languages in the world. Through this project, researchers will gain access to corpora which they have not been able to study before and to which all users will have open access regardless of their place of residence. In my presentation, I will discuss 1) how we utilized the social media (Facebook, Twitter, VKontakte etc) to gain audience for our collection and 2) how the needs of researchers and laymen were met in crowdsourcing.

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Työilmoitus voi jäädä työnhakijan ja työnantajan välillä ainoaksi viestinnän mahdollisuudeksi, jolloin ratkaisevaa on, kuinka houkuttelevaksi työnantaja työilmoituksensa laatii kilpaillessaan halutuista osaajista. Samalla työilmoitus antaa lupauksia tulevasta työstä ja työyhteisöstä. Tämän tutkimuksen perimmäinen tarkoitus on tutkia, näkyykö työsuhteen kahdenvälinen transaktioluonne työilmoitusten tasolla eli kerrotaanko ilmoituksissa työnantajan osaajatarpeiden lisäksi, mitkä olisivat työntekijän työllistymisellä saavutetut hyödyt. Tarkemmiksi tarkastelun kohteiksi on valittu kaksi työnhakijan päätöksenteon kannalta mielenkiintoista näkökulmaa: viestityt työarvot ja työnantajalupaukset. Teoreettiselta taustaltaan tämä tutkimus liittyy rekrytoinnin kokonaisuuteen, mutta se sivuaa useita muita aihealueita, kuten yksilön ja yrityksen yhteensopivuutta, työnantajamielikuvaa, psykologista sopimusta, informaation prosessointia, suostuttelua ja työnhakupäätöksen syntymekanismin tutkimusta. Tutkimuksen empiirinen aineisto koostuu kolmena peräkkäisenä vuonna (2013−2015) Suomen parhaimmiksi työnantajiksi tituleerattujen yritysten julkaisemista työilmoituksista. Näiden oletettiin olevan kiinnostuneita työnantajakuvastaan ja rekrytoinnistaan keskimääräistä enemmän. Kerätyistä 19 työilmoituksesta tulkittiin arvoilmaisuja ja annettuja esilupauksia kahden teoreettisen luokituksen yhdistelmänä muodostetun analyysirungon avulla. Aineiston lauseita eriteltiin analyysirungon teemojen alle ja niiden vakuuttamiskeinoja analysoitiin retorisella diskurssianalyysillä. Tutkimuksen tuloksena havaittiin, että työnteon puitteista, palkkatiedoista, määräysvallasta ja työn merkityksellisyydestä mainittiin verrattain vähän työilmoituksissa. Sen sijaan aineiston työilmoituksista löytyi runsaasti ilmaisuja, joista työnhakija voi tehdä päätelmiä työilmapiiristä tai potentiaalisten kollegoiden asiantuntijuuden tasosta. Yrittäjähenkisyys- ja suorituspainepuheiden läpi heijastui puolestaan kovemmat arvot. Arvojen ilmaisu tapahtui usein epäsuorasti kuin selkeinä arvolistoina. Konkreettisia lupauksia työnantajalta työnhakijalle tehtiin vähän tai ne olivat ylimalkaisia. Tutkimus antaa aihetta laajemmille kartoituksille. Mitkä ovat syyt tiettyä kaavaa toistavien työilmoitusten taustalla ja mitkä tekijät työilmoituksissa eri kohdeyleisöjä aidosti vaikuttavat?