Ilmastonmuutoksen vaikutus arktisten virtavesien biodiversiteettiin

Tiivistelmä. Arktinen alue on hyvin omalaatuinen ja monimuotoinen elinympäristö johtuen sen ankarista ilmasto-olosuhteista. Nyt ilmaston lämmetessä arktiset elinympäristöt ovat suurien muutosten äärellä, sillä ilmaston lämmetessä esimerkiksi alueella tavattava ikirouta sulaa. Elinympäristöjen muuttuminen ilmaston lämpenemisen ja esimerkiksi maankäytön muutosten vuoksi tulee vaikuttamaan negatiivisesti alueiden biodiversiteettiin. Erilaiset makean veden ekosysteemit ovat tärkeä osa arktista aluetta, sillä ne ovat suhteessa monimuotoisempia kuin maaekosysteemit ja ne tuottavat esimerkiksi tärkeitä ekosysteemipalveluita. Arktisten virtavesien ekosysteemit koostuvat monista erilaisista prosesseista, ja niihin vaikuttaa suuresti myös niiden valuma- ja ranta-alueet, joten ne ovat herkkiä ilmastonmuutoksen tuomille muutoksille. Ilman lämpötilan kohoaminen tuo mukanaan monenlaisia ongelmia. Esimerkiksi veden lämpötilan nousu tulee vaikuttamaan negatiivisesti lajeihin, jotka ovat tottuneet kylmiin vesiin. Jääpeitteen väheneminen lisää valon määrää joissa, joka voi kiihdyttää rehevöitymistä. Lumen määrän väheneminen vähentää makean veden määrää arktisella alueella. Kaikki nämä tuottavat haasteita alueiden eliöille ja vaikuttavat näin negatiivisesti biodiversiteettiin. Ilmaston lämmetessä levittäytyvät ihmiset ja erilaiset lajit pohjoisempaan päin. Eteläisten lajien leviäminen yhä pohjoisemmille alueille tuottaa kilpailua alueen alkuperäiselle lajistolle ja vie niiltä resursseja. Ihmistoiminnan levittäytyessä yhä pohjoisempaan leviää erilaiset maankäytön muutokset ja esimerkiksi turismi yhä syrjäisemmille alueille muuttaen näin habitaatteja ja vaikeuttamalla organismien selviytymistä. Biologisen seurannan tila arktisella alueella on ollut epäsäännöllistä ja riittämätöntä. Tähän suurimpana syynä on ollut resurssipula. Tähän voisi olla yhtenä ratkaisuna arktisen alueen yhteisöjen mukaanotto seurannan suorittamiseen. Tärkeää olisi saada koko arktisen alueen kattava säännöllinen seurantasuunnitelma, jotta alueesta ja siellä tapahtuvista muutoksista tiedettäisiin mahdollisimman paljon. Näin arktisen alueen suojelua voitaisiin toteuttaa mahdollisimman tehokkaasti

Measurements of hydrocarbon emissions from a boreal fen using the REA technique

International audienceFluxes of biogenic volatile organic compounds (VOC) and methane were measured above a boreal fen. Vegetation on the fen is dominated by Sphagnum mosses and sedges. A relaxed eddy accumulation (REA) system with dynamic deadband was designed and constructed for the measurements. Methane, C2-C6 hydrocarbons and some halogenated hydrocarbons were analysed from the samples by gas chromatographs equipped with FID and ECD. A significant flux of isoprene and methane was detected during the growing seasons. Isoprene emission was found to follow the common isoprene emission algorithm. Average standard emission potential of isoprene was 680 ? g m-2h-1. Fluxes of other non-methane hydrocarbons were below detection limit

Technical Note: Quantitative long-term measurements of VOC concentrations by PTR-MS ? measurement, calibration, and volume mixing ratio calculation methods

International audienceProton transfer reaction mass spectrometry (PTR-MS) is a technique for online measurements of atmospheric concentrations, or volume mixing ratios, of volatile organic compounds (VOCs). The aim of this paper is to give a detailed description of our measurement, calibration, and volume mixing ratio calculation methods, which have been designed for long-term stand-alone field measurements by PTR-MS. We also show how the information obtained from a calibration can be used to determine the instrument specific relative transmission curve, which enables quantitative mixing ratio calculation for VOCs which are not present in a calibration gas standard. To illustrate the functionality of our measurement, calibration, and calculation methods, we present a one-month period of ambient mixing ratio data measured in a boreal forest ecosystem at the SMEAR II station in southern Finland. During the measurement period 27 March?26 April 2007, the hourly averages of mixing ratios were 0.1?0.5 ppbv for formaldehyde, 0.2?3.0 ppbv for methanol, 0.04?0.39 ppbv for benzene, and 0.03?1.25 ppbv for monoterpenes

Winter to spring transition and diurnal variation of VOCs in Finland at an urban background site and a rural site

Peer reviewe

LIBS applicability for investigation of re-deposition and fuel retention in tungsten coatings exposed to pure and nitrogen-mixed deuterium plasmas of Magnum-PSI

We have investigated the applicability of Laser Induced Breakdown Spectroscopy (LIBS) for analyzing the changes in the composition and fuel retention of W and W-Ta coatings following exposure to D2 or mixed D2-N2 plasma beams in the linear plasma device Magnum PSI. The exposed samples were characterized by in situ ns-LIBS and complementary analysis methods Secondary Ion Mass Spectroscopy, Energy Dispersive x-ray spectroscopy and Nuclear Reaction Analysis. In agreement with the used complementary analysis methods, LIBS revealed the formation of up to 400 nm thick co-deposited surface layer in the central region of the coatings which contained a higher concentration of the main plasma impurities, such as N, and metals, such as Ta and Mo, the latter originating mainly from the substrate and from the plasma source. The deuterium retention on the other hand was highest outside from the central region of the coatings.</p

ERO modelling of net and gross erosion of marker samples exposed to L-mode plasmas on ASDEX Upgrade

In this paper, we report experimental and numerical investigations of gross and net erosion of gold (Au) and molybdenum (Mo), proxies for the common plasma-facing material tungsten (W), during L-mode plasma discharges in deuterium (D) in the outer strike-point region of the ASDEX Upgrade tokamak. To this end, erosion profiles of different marker spots (for Au, dimensions 1 x 1 and 5 x 5 mm(2)) and marker coatings (for Mo) have been determined and modelled using the ERO code. The smaller marker spots were designed to quantify the gross-erosion rate while on the bigger markers local prompt re-deposition of Au allowed obtaining data on net erosion. The experimental results indicate relatively uniform erosion profiles across the marker spots or coatings, very little re-deposition elsewhere, and the largest erosion taking place close to the strike point. Compared to W, the markers show up to 15 times higher net erosion but no major differences in the poloidal migration lengths of Au and W can be seen. Gold thus appears to be a proper choice for studying migration of W in the divertor region. The ERO simulations with different background plasmas are able to reproduce the main features of the experimental net erosion profile of Au. Of the studied parameters, electron temperature has the strongest impact on erosion: doubling the temperature enhances erosion by a factor of 2.5-3. In contrast, for Mo, the simulated net erosion is similar to 3 times smaller than what experimental data indicate. The discrepancies can be attributed to the deviations of the background plasma profiles from the measured ones as well as to the applied models or approximations for the ion temperature, plasma potential, and sheath characteristics in ERO. In addition, the surrounding areas of the marker samples being covered with impurities and W from previous experiments may have considerably reduced the actual re-deposition of Mo. All the simulations predict a toroidal tail of re-deposited particles, downstream of the markers, but the particle density seems to be below the experimental detection threshold. The comparison between the 1 x 1 mm(2) and 5 x 5 mm(2) marker spots further reveal that re-deposition drops from >50% toPeer reviewe

Measurements of hydrocarbon emissions from a boreal fen using the REA technique

Fluxes of biogenic volatile organic compounds (VOC) and methane were measured above a boreal fen. Vegetation on the fen is dominated by Sphagnum mosses and sedges. A relaxed eddy accumulation (REA) system with dynamic deadband was designed and constructed for the measurements. Methane, C-2-C-6 hydrocarbons and some halogenated hydrocarbons were analysed from the samples by gas chromatographs equipped with FID and ECD. A significant flux of isoprene and methane was detected during the growing seasons. Isoprene emission was found to follow the common isoprene emission algorithm. Average standard emission potential of isoprene was 680 mu g m(-2) h(-1). Fluxes of other non-methane hydrocarbons were below detection limit.Fluxes of biogenic volatile organic compounds (VOC) and methane were measured above a boreal fen. Vegetation on the fen is dominated by Sphagnum mosses and sedges. A relaxed eddy accumulation (REA) system with dynamic deadband was designed and constructed for the measurements. Methane, C-2-C-6 hydrocarbons and some halogenated hydrocarbons were analysed from the samples by gas chromatographs equipped with FID and ECD. A significant flux of isoprene and methane was detected during the growing seasons. Isoprene emission was found to follow the common isoprene emission algorithm. Average standard emission potential of isoprene was 680 mu g m(-2) h(-1). Fluxes of other non-methane hydrocarbons were below detection limit.Fluxes of biogenic volatile organic compounds (VOC) and methane were measured above a boreal fen. Vegetation on the fen is dominated by Sphagnum mosses and sedges. A relaxed eddy accumulation (REA) system with dynamic deadband was designed and constructed for the measurements. Methane, C-2-C-6 hydrocarbons and some halogenated hydrocarbons were analysed from the samples by gas chromatographs equipped with FID and ECD. A significant flux of isoprene and methane was detected during the growing seasons. Isoprene emission was found to follow the common isoprene emission algorithm. Average standard emission potential of isoprene was 680 mu g m(-2) h(-1). Fluxes of other non-methane hydrocarbons were below detection limit.Peer reviewe