1000 resultados para 411 Maatalous ja metsätieteet
Resumo:
Lakes are an important component of ecosystem carbon cycle through both organic carbon sequestration and carbon dioxide and methane emissions, although they cover only a small fraction of the Earth's surface area. Lake sediments are considered to be one of rather perma-nent sinks of carbon in boreal regions and furthermore, freshwater ecosystems process large amounts of carbon originating from terrestrial sources. These carbon fluxes are highly uncer-tain especially in the changing climate. -- The present study provides a large-scale view on carbon sources and fluxes in boreal lakes situated in different landscapes. We present carbon concentrations in water, pools in lake se-diments, and carbon gas (CO2 and CH4) fluxes from lakes. The study is based on spatially extensive and randomly selected Nordic Lake Survey (NLS) database with 874 lakes. The large database allows the identification of the various factors (lake size, climate, and catchment land use) determining lake water carbon concentrations, pools and gas fluxes in different types of lakes along a latitudinal gradient from 60oN to 69oN. Lakes in different landscapes vary in their carbon quantity and quality. Carbon (C) content (total organic and inorganic carbon) in lakes is highest in agriculture and peatland dominated areas. In peatland rich areas organic carbon dominated in lakes but in agricultural areas both organic and inorganic C concentrations were high. Total inorganic carbon in the lake water was strongly dependent on the bedrock and soil quality in the catchment, especially in areas where human influence in the catchment is low. In inhabited areas both agriculture and habitation in the catchment increase lake TIC concentrations, since in the disturbed soils both weathering and leaching are presumably more efficient than in pristine areas. TOC concentrations in lakes were related to either catchment sources, mainly peatlands, or to retention in the upper watercourses. Retention as a regulator of the TOC concentrations dominated in southern Finland, whereas the peatland sources were important in northern Finland. The homogeneous land use in the north and the restricted catchment sources of TOC contribute to the close relationship between peatlands and the TOC concentrations in the northern lakes. In southern Finland the more favorable climate for degradation and the multiple sources of TOC in the mixed land use highlight the importance of retention. Carbon processing was intensive in the small lakes. Both CO2 emission and the Holocene C pool in sediments per square meter of the lake area were highest in the smallest lakes. How-ever, because the total area of the small lakes on the areal level is limited, the large lakes are important units in C processing in the landscape. Both CO2 and CH4 concentrations and emissions were high in eutrophic lakes. High availability of nutrients and the fresh organic matter enhance degradation in these lakes. Eutrophic lakes are often small and shallow, enabling high contact between the water column and the sediment. At the landscape level, the lakes in agricultural areas are often eutrophic due to fertile soils and fertilization of the catchments, and therefore they also showed the highest CO2 and CH4 concentrations. Export from the catchments and in-lake degradation were suggested to be equally important sources of CO2 and CH4 in fall when the lake water column was intensively mixed and the transport of sub-stances from the catchment was high due to the rainy season. In the stagnant periods, especially in the winter, in-lake degradation as a gas source was highlighted due to minimal mixing and limited transport of C from the catchment. The strong relationship between the annual CO2 level of lakes and the annual precipitation suggests that climate change can have a major impact on C cycling in the catchments. Increase in precipitation enhances DOC export from the catchments and leads to increasing greenhouse gas emissions from lakes. The total annual CO2 emission from Finnish lakes was estimated to be 1400 Gg C a-1. The total lake sediment C pool in Finland was estimated to be 0.62 Pg, giving an annual sink in Finnish lakes of 65 Gg C a-1.
Resumo:
Nature conservation in everyday life: Private landowners perceptions of and experiences on temporary nature conservation and its renewing process This study explores the legitimacy of official nature conservation of private lands. It describes how temporary nature conservation became a part of Finnish nature conservation policy and how forest owners perceived this tool and its usage. In addition, the study analyses forest owners' attitudes on official nature conservation. The study combines individual and official perspectives, and presents a nature conservation politics of everyday life. The theoretical background of the study is learning processes of environmentally responsible participation, and especially empowerment. Main methods in gathering the material for the study have been interviews and a survey. In the 1990 s, Finnish landowners opposed the implementation of nature conservation, especially conservation of shores and the establishment of the European-wide network of conservation areas (Natura 2000). After negative experiences on these conservation efforts, some private landowners were disempowered and some even rejected conservation completely. The Nature Conservation Act of 1996 launched an option to conserve nature officially for fixed time-periods. Use of such a policy tool did not immediately become a widely-used and appreciated conservation practice. During the following decade, however, it attracted remarkable attention within Finnish nature conservation policy discussions. The perspective of landowners began to be emphasised when local and regional organisations for nature conservation and forestry together defined the ideas of natural values trading. Later, the national governance process of the committee defining the Forest Biodiversity Programme for Southern Finland (METSO) institutionalised these ideas in one of its pilot projects. Landowners participated in the project of natural values trading by offering their forests for conservation, which reflects the increased acceptance and legitimacy of nature conservation on private forests. The central elements producing the legitimacy of natural values trading have been voluntariness, temporariness, and dialogue between nature conservation and forestry. Natural values trading analysed in the study is an example of new environmental policy instruments and its creation process represents governance in the implementation of nature conservation. It has increased the legitimacy of nature conservation policy of private forests in Finland. The results reveal the importance of participation and learning processes in the implementation of nature conservation policy, and the need to also pay attention to these processes in the future.
Resumo:
Samanaikainen alkoholiriippuvuus ja vakava masennustila on haasteellista sekä lääketieteelliselle hoidolle että tutkimukselle. Tämä oireyhtymä on yksi yleisimmistä psykiatrisista häiriöistä niin Yhdysvalloissa kuin Suomessakin. Potilaiden ja heidän omaistensa inhimillisen kärsimyksen lisäksi myös kokonaistaloudelliset terveydenhoidolliset kustannukset ovat suuret tämän oireyhtymän hoidossa: niiden arvioidaan olevan yli neljäkymmentä prosenttia korkeammat kuin pelkän depression kohdalla. Tässä tutkimuksessa pyrittiin löytämään uusia hoidollisia vaihtoehtoja alkoholiriippuvuudesta ja vakavasta masennuksesta yhtäaikaisesti kärsivien potilaiden hoidossa. Tutkimukseen osallistui 80 potilasta Helsingin kaupungin kolmelta A-klinikalta. Kyseessä oli kaksoissokko, randomisoitu, kahden eri tavalla vaikuttavan lääkkeen, essitalopraamin (selektiivinen serotoniinin takaisinoton estäjä) ja memantiinin (glutamaatin NMDA reseptorin ei-kilpaileva estäjä) vertaileva tutkimus. Potilaiden oireiden kulkua seurattiin 26 viikkoa depressioon, ahdistuneisuuteen, kogniitioihin, elämänlaatuun ja alkoholin käyttöön liittyvillä mittareilla. Tämän jälkeen tarkasteltiin hoitovastetta alkutilanne- ja taustamuuttujien valossa. Pyrkimyksenä oli löytää joitakin ennustekijöitä, joiden pohjalta kliinikko voisi tehdä hoitoratkaisunsa näiden potilaiden hoidossa. Molemmat lääkkeet vähensivät merkittävästi sekä masennusta että ahdistuneisuutta, eikä essitalopraami- ja memantiiniryhmien välillä ollut tilastollisesti merkitsevää eroa. Kognitiiviset toiminnot olivat lähtövaiheessa normatiivisella tasolla. Elämän laatu parani molemmissa hoitoryhmissä. Alkoholimittareilla AUDIT (alkoholihäiriöiden tunnistusmittari) ja OCDS (pakkomielteisen ja pakkotoimintoisen alkoholinkäytön mittari) paranivat molemmissa hoitoryhmissä. Varhainen ensimmäisen vakavan masennuksen episodin alku näytti ennakoivan huonoa vastetta essitalopraamille, mutta ei memantiinille, mitattuna Montgomery-Åsberg depression rating scale -asteikolla. Toisaalta myöhäinen ensimmäisen masennuksen episodi näytti ennakoivan hyvää hoitovastetta essitalopraamille. Niinpä ensimmäisen masennuksen alkamisikä saattaisi olla käyttökelpoinen ennustekijä näille lääkkeille. Varhainen humalahakuisen juomisen alkamisikä näytti ennustavan huonoa hoitovastetta molemmille lääkkeille, erityisesti essitalopraamille, mitattuna AUDIT-mittarilla. Aktiivinen alkoholinkäyttö tutkimuksen alkaessa ennakoi tutkimuksen keskeyttämistä. HTTLPR-geenin L-alleeli näytti ennustavan parempaa hoitovastetta essitalopraamille masennukseen kuin S-alleeli.