Kasvihuonekaasut, soiden näkymättömät vaikuttajat

Hiiltä sisältävät "kasvihuonekaasut", kuten hiilidioksidi ja metaani, sitovat maapallon heijastamaa lämpöenergiaa tehostaen ilmakehän lämpenemistä. Ilmakehän kaasukoostumuksen ja lämpenemisen välillä on tietysti aina ollut yhteys. Teollisen ihmisen vaikutuksesta eräiden kaasujen määrä on kasvanut nopeasti viime vuosikymmeninä voimistaen ilmakehän kasvihuoneilmiötä. Muinoin syntyneitä fossiileja poltetaan energiaksi ja hiili on nyt äkkiä palaamassa ilmakehään hiilidioksidina. Lisääntynyt riisinviljely ja märehtijöiden kasvatus, kaatopaikkajätteen mätäneminen, maakaasuvuodot sekä biomassan poltto ovat puolestaan lisänneet metaanipäästöjä. Luonnon kosteikot osallistuvat hiilidioksidin ja metaanin taseisiin. Soisessa Suomessa varsinkin ojitettujen, mutta myös koskemattomien soiden hiilitase kiinnostaa meitä päästäjiä

Responses of Scots pine to wintertime flooding

Poster

Lakes as nitrous oxide sources in the boreal landscape

Abstract Estimates of regional and global freshwater N2O emissions have remained inaccurate due to scarce data and complexity of the multiple processes driving N2O fluxes the focus predominantly being on summer time measurements from emission hot spots, agricultural streams. Here we present four-season data of N2O concentrations in the water columns of randomly selected boreal lakes covering a large variation in latitude, lake type, area, depth, water chemistry and land use cover. Nitrate was the key driver for N2O dynamics, explaining as much as 78% of the variation of the seasonal mean N2O concentrations across all lakes. Nitrate concentrations varied among seasons being highest in winter and lowest in summer. Of the surface water samples 71% were oversaturated with N2O relative to the atmosphere. Largest oversaturation was measured in winter and lowest in summer stressing the importance to include full year N2O measurements in annual emission estimates. Including winter data resulted in four-fold annual N2O emission estimates compared to summer only measurements. Nutrient rich calcareous and large humic lakes had the highest annual N2O emissions. Our emission estimates for Finnish and boreal lakes are 0.6 Gg and 29 Gg N2O-N y-1, respectively. The Global Warming Potential (GWP) of N2O cannot be neglected in the boreal landscape, being 35% of that of diffusive CH4 emission in Finnish lakes.peerReviewe

Towards Transformational Creation of Novel Songs

We study transformational computational creativity in the context of writing songs and describe an implemented system that is able to modify its own goals and operation. With this, we contribute to three aspects of computational creativity and song generation: (1) Application-wise, songs are an interesting and challenging target for creativity, as they require the production of complementary music and lyrics. (2) Technically, we approach the problem of creativity and song generation using constraint programming. We show how constraints can be used declaratively to define a search space of songs so that a standard constraint solver can then be used to generate songs. (3) Conceptually, we describe a concrete architecture for transformational creativity where the creative (song writing) system has some responsibility for setting its own search space and goals. In the proposed architecture, a meta-level control component does this transparently by manipulating the constraints at runtime based on self-reflection of the system. Empirical experiments suggest the system is able to create songs according to its own taste.Peer reviewe