Search

Soils play multiple roles in vital ecosystem processes, even though they form only a thin layer between Earth’s atmosphere and lithosphere. Soils are reservoirs of carbon, most nutrients and fresh water while acting as a substrate for plants, a site for decomposition processes, and a sink for harmful substances. The decomposition of dead organic matter and the associated recycling of nutrients are a prerequisite for photosynthesis by green plants and, therefore, for all life forms on Earth. Without healthy soils, the integrity of the Earth system cannot be maintained in the future. Soils are highly diverse habitats, inhabited by both structurally and functionally diversified organisms. However, human activity is currently threatening both soil health and biodiversity. Intensive farming, mining, deforestation, pollution, and urbanization are significantly reducing the area of undisturbed land and simplifying the soil structure. This also represents a threat to nature’s contributions to people. On the road to planetary well-being, humanity should therefore pay particular attention to soils. This chapter discusses how soil processes contribute to the well-being of our planet and how the impacts of human activities on soil affect planetary well-being. peerReviewed

Increasing concentration of iron (Fe) is observed in many boreal lakes, such as for the present study in Oslo Østmark, SE-Norway (1983–2018). As Fe-regulating processes are complex and dynamic, the link between mobilizing and retention processes is still not well understood. A seasonal study (2017–2018) from two headwaters, with medium and high dissolved organic matter (DOM) concentrations, showed that the loading of Fe to the lakes was highly dependent on flow conditions. Significantly higher values of Fe were related to autumn and winter periods with high runoff of highly colored and aromatic DOM compared to a severe drought period with minimum Fe values in the lakes. Compared to DOM, a significantly larger part of Fe was in a colloidal form, and a size-selective process (dependent on flow and water retention time) seemed to preferentially settle Fe compared to DOM. In contrast to Fe, the variability in DOM concentrations was moderate through the whole year. However, there were significant changes in the spectroscopic properties of DOM, with decreased fluorescence intensity and increased spectral slope during the warm dry season, indicating increased importance of DOM turnover in the lake. As Fe was transported from the catchment during high flow condition, at the same time as the oxic form of sulfur (SO42−), there was no sign of retention of Fe as FeS. We conclude that the mobilization and retention of compounds that are mainly in a colloidal form, such as Fe, are especially vulnerable to changes in flow conditions, suggesting increased variation in Fe levels in a future climate with increased frequency of flooding and drought episodes.

Current knowledge on the seasonality of benthic nitrate reduction pathways in the aphotic, density stratified coastal zone of the Baltic Sea is largely based on data from muddy sediments, neglecting the potential contribution of sandy sediments. To gain a more comprehensive understanding of seasonality in this part of the Baltic Sea coast, we measured rates of benthic denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA) monthly in the ice-free period of 2016 in both sandy and muddy aphotic sediments, northwestern Gulf of Finland. No anammox was observed. The seasonal cycle of denitrification in both sediment types was related to the hydrography-driven development of bottom water temperature. The seasonal cycle of DNRA was less clear and likely connected to a combination of bottom water temperature, carbon to nitrogen ratio, and substrate competition with denitrification. Denitrification and DNRA rates were 50-80 and 20% lower in the sandy than in the muddy sediment. The share of DNRA in total nitrate reduction, however, was higher in the sandy than in the muddy sediment, being (by similar to 50%) the highest DNRA share in sandy sediments so far measured. Our data add to the small pool of published studies showing significant DNRA in both cold and/or sandy sediments and suggest that DNRA is currently underestimated in the Baltic coastal nitrogen filter. Our results furthermore emphasize that the various environmental conditions of a coastal habitat (light regime, hydrography, and geomorphology) affect biogeochemical element cycling and thus need to be considered in data interpretation.

Dramatic environmental shifts are occuring throughout the Arctic from climate change, with consequences for the cycling of mercury (Hg). This review summarizes the latest science on how climate change is influencing Hg transport and biogeochemical cycling in Arctic terrestrial, freshwater and marine ecosystems. As environmental changes in the Arctic continue to accelerate, a clearer picture is emerging of the profound shifts in the climate and cryosphere, and their connections to Hg cycling. Modeling results suggest climate influences seasonal and interannual variability of atmospheric Hg deposition. The clearest evidence of current climate change effects is for Hg transport from terrestrial catchments, where widespread permafrost thaw, glacier melt and coastal erosion are increasing the export of Hg to downstream environments. Recent estimates suggest Arctic permafrost is a large global reservoir of Hg, which is vulnerable to degradation with climate warming, although the fate of permafrost soil Hg is unclear. The increasing development of thermokarst features, the formation and expansion of thaw lakes, and increased soil erosion in terrestrial landscapes are increasing river transport of particulate-bound Hg and altering conditions for aquatic Hg transformations. Greater organic matter transport may also be influencing the downstream transport and fate of Hg. More severe and frequent wildfires within the Arctic and across boreal regions may be contributing to the atmospheric pool of Hg. Climate change influences on Hg biogeochemical cycling remain poorly understood. Seasonal evasion and retention of inorganic Hg may be altered by reduced sea-ice cover and higher chloride content in snow. Experimental evidence indicates warmer temperatures enhance methylmercury production in ocean and lake sediments as well as in tundra soils. Improved geographic coverage of measurements and modeling approaches are needed to better evaluate net effects of climate change and long-term implications for Hg contamination in the Arctic. Highlights • Current evidence indicates climate change is influencing Hg cycling in the Arctic. • Permafrost thaw, glacier melt, and coastal erosion are increasing Hg export. • Arctic permafrost is a global Hg reservoir, vulnerable to degradation and release. • Experiments show warmer temperatures increase MeHg in Arctic sediments and soils. • Net effects of climate change on Arctic Hg contamination remain poorly resolved.

Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low-nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization are poorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low-nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, and were strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature-dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature. Collectively, we demonstrated that exogenous nutrient supply and immobilization are critical control points for decomposition of organic matter. Key Points • Nitrogen (N) and phosphorus (P) immobilization was measured on organic matter (cotton) in 100 rivers and riparian zones representing 11 biomes • Elevated temperature in riparian zones and phosphate in rivers increased immobilization, and consequently accelerated decomposition • N and P immobilization was strongly linked by microbial stoichiometry despite widely varied surface-water nutrient ratios Plain Language Summary Bacteria and fungi contribute to the breakdown of leaf litter in rivers and floodplains. To break down leaf litter, these microbes need the nutrients nitrogen and phosphorus (P), and microbes can get nutrients either from the leaf litter itself or from the environment. Most leaf litter has low nutrient content and microbes must rely on the environment to supply nutrients. We studied microbial nutrient uptake from the environment during litter breakdown to determine whether it varies predictably across the globe and how it is influenced by changing climate and nutrient pollution. In 100 rivers and floodplains in 11 of Earth's major biomes we placed small strips of cotton as stand-ins for leaf litter. Nutrient uptake was consistently greater on cotton strips that were submerged in the river compared to cotton on the floodplain. For microbes in the river, nutrient uptake was faster in instances where there was more P in the water. For microbes in the floodplain, nutrient uptake was faster where temperatures were warmer. Faster nutrient uptake by microbes was linked with faster cotton breakdown in rivers and floodplains. Our study shows that climate change and nutrient pollution can alter the activity of microbes in rivers and floodplains.

Soils are important sources of nitric oxide (NO) and nitrous acid (HONO) in the atmosphere. These nitrogen (N)-containing gases play a crucial role in atmospheric chemistry and climate at different scales because of reactions modulated by NO and hydroxyl radicals (OH), which are formed via HONO photolysis. Northern permafrost soils have so far remained unexplored for HONO and NO emissions despite their high N stocks, capacity to emit nitrous oxide (N2O), and enhancing mineral N turnover due to warming and permafrost thawing. Here, we report the first HONO and NO emissions from high-latitude soils based on measurements of permafrost-affected subarctic peatlands. We show large HONO (0.1–2.4 µg N m−2h−1) and NO (0.4–59.3 µg N m−2h−1) emissions from unvegetated peat surfaces, rich with mineral N, compared to low emissions (⩽0.2 µg N m−2h−1 for both gases) from adjacent vegetated surfaces (experiments with intact peat cores). We observed HONO production under highly variable soil moisture conditions from dry to wet. However, based on complementary slurry experiments, HONO production was strongly favored by high soil moisture and anoxic conditions. We suggest urgent examination of other Arctic landscapes for HONO and NO emissions to better constrain the role of these reactive N gases in Arctic atmospheric chemistry. peerReviewed

Highlights • Fe has a key role in biogeochemical and ecological contexts in boreal catchments. • Fe has many harmful impacts on aquatic organisms and ecosystems. • Drivers of Fe transport should be better known in water management. • Catchment-scale approaches are required to create effective management of Fe. Iron (Fe) is an important element in aquatic ecosystems worldwide because it is intimately tied with multiple abiotic and biotic phenomena. Here, we give a survey of manifold influences of Fe, and the key factors affecting it in the boreal catchments and their waters. It includes the perspectives of biogeochemistry, hydrology, ecology, and river basin management. We emphasize views on the dynamics and impacts of different forms of Fe in riverine environments, including organic colloids and particles, as well as inorganic fractions. We also provide perspectives for land use management in boreal catchments and suggest guidelines for decision making and water management. Based on our survey, the main emphases of water protection and management programs should be (i) prevention of Fe mobilization from soil layers by avoiding unnecessary land-use activities and minimizing soil disturbance in high-risk areas; (ii) disconnecting Fe-rich ground water discharge from directly reaching watercourses; and (iii) decreasing transport of Fe to watercourses by applying efficient water pollution control approaches. These approaches may require specific methods that should be given attention depending on catchment conditions in different areas. Finally, we highlight issues requiring additional research on boreal catchments. A key issue is to increase our understanding of the role of Fe in the utilization of DOM in riverine food webs, which are typically highly heterotrophic. More knowledge is needed on the metabolic and behavioral resistance mechanisms that aquatic organisms, such as algae, invertebrates, and fish, have developed to counter the harmful impacts of Fe in rivers with naturally high Fe and DOM concentrations. It is also emphasized that to fulfil the needs presented above, as well as to develop effective methods for decreasing the harmful impacts of Fe in water management, the biogeochemical processes contributing to Fe transport from catchments via rivers to estuaries should be better understood.

Despite their key role in biogeochemical processes, particularly the methane cycle, archaea are widely underrepresented in molecular surveys because of their lower abundance compared to bacteria and eukaryotes. Here, we use parallel high‐resolution small subunit rRNA gene sequencing to explore archaeal diversity in 109 Swedish lakes and correlate archaeal community assembly mechanisms to large‐scale latitudinal, climatic (nemoral to arctic), and nutrient (oligotrophic to eutrophic) gradients. Sequencing with universal primers showed the contribution of archaea was on average 0.8% but increased up to 1.5% of the three domains in forest lakes. Archaea‐specific sequencing revealed that freshwater archaeal diversity could be partly explained by lake variables associated with nutrient status. Combined with deterministic co‐occurrence patterns this finding suggests that ecological drift is overridden by environmental sorting, as well as other deterministic processes such as biogeographic and evolutionary history, leading to lake‐specific archaeal biodiversity. Acetoclastic, hydrogenotrophic and methylotrophic methanogens as well as ammonia‐oxidizing archaea were frequently detected across the lakes. Archaea‐specific sequencing also revealed representatives of Woesearchaeota and other phyla of the DPANN superphylum. This study adds to our understanding of the ecological range of key archaea in freshwaters and links these taxa to hypotheses about processes governing biogeochemical cycles in lakes. peerReviewed

The majority of the carbon worldwide is in soil. In a river catchment, the tight relationship between soil, water and climate makes carbon likely to be eroded and transported from the soil to the rivers. There are multiple variables which can trigger and accelerate the process. In order to assess the importance of the factors involved, and their interactions resulting in the changes in the carbon cycle within catchments, we have studied the catchments of 26 Finnish rivers from 2000 to 2019. These catchments are distributed all over Finland, but we have grouped them into three categories: southern, peatland and northern. We have run a boosted regression tree (BRT) analysis on chemical, physical, climatic and anthropogenic factors to determine their influence on the variations of total organic carbon (TOC) concentration. TOC concentration has decreased in Finland between 2000 and 2019 by 0.91 mg/l, driven principally by forest ditching and % old forest in the catchment. Old forest is especially dominant in the northern catchments with an influence on TOC of 40.5%. In southern and peatland catchments, average precipitation is an important factor to explain the changes in TOC whilst in northern catchments, organic fields have more influence.

Lakes are a dominant feature of the Arctic landscape and a focal point of regional and global biogeochemical cycling. We collected a sediment core from a High Arctic Lake in southwestern Svalbard for multiproxy paleolimnological analysis. The aim was to find linkages between the terrestrial and aquatic environments in the context of climate change to understand centennial-long Arctic biogeochemical cycling and environmental dynamics. Two significant thresholds in elemental cycling were found based on sediment physical and biogeochemical proxies that were associated with the end of the cold Little Ice Age and the recent warming. We found major shifts in diatom, chironomid and cladoceran communities and their functionality that coincided with increased summer temperatures since the 1950s. We also discovered paleoecological evidence that point toward expanded bird (Little Auk) colonies in the catchment alongside climate warming. Apparently, climate-driven increase in glacier melt water delivery as well as a prolonged snow- and ice-free period have increased the transport of mineral matter from the catchment, causing significant water turbidity and disappearance of several planktonic diatoms and clear-water chironomids. We also found sedimentary accumulation of microplastic particles following the increase in Little Auk populations suggesting that seabirds potentially act as biovectors for plastic contamination. Our study demonstrates the diverse nature of climate-driven changes in the Arctic lacustrine environment with increased inorganic input from the more exposed catchment, larger nutrient delivery from the increased bird colonies at the surrounding mountain summits and subsequent alterations in aquatic communities.

Protection measures are needed to control nutrient leaching from agriculture to the Baltic Sea. Ecological Recycling Agriculture (ERA) is based on local nutrient resources, integrating animal and crop production on farms or in their proximity. In Finland, three agricultural study catchments were chosen to demonstrate environmental impacts of ERA. Inorganic nitrogen (N) leaching from the catchments was simulated with INCA-N model in prevailing and ERA farming conditions. Lepsamanjoki catchment is a crop production area, in the Ylaneenjoki catchment animal husbandry is common and in the Lestijoki catchment the main production line is dairy production. A theoretical crop rotation was developed to represent ERA cultivation consisting of leys, cereals and mixture of cereals and pea. N fixation, mineralization and manure were sources of N. INCA-N was calibrated in the catchments using present cultivation practices. Next, crop parameters were modified to describe ERA cultivation. The model results showed that ERA has potential to decrease N losses: the highest inorganic stream N concentrations and average annual inorganic N losses from agricultural fields decreased, compared to those resulting from present production relying on inorganic fertilizers. Therefore, ERA may serve as one of the measures to achieve the N reduction targets set for agriculture in the Baltic Sea Action Plan.

Dissolved organic nitrogen (DON) represents a significant reservoir of potentially plant available nitrogen (N) in saltmarsh ecosystems and wastewater treatment streams. Here we investigated the capacity of two halophytic plants used in wastewater remediation, Salicornia europaea and Aster tripolium, to access soluble organic forms of N when grown in water or soil-based culture. Incubation experiments with 15N13C- and 14C-labelled alanine and trialanine, 15NH4+ and 15NO3− indicated that both S. europaea and A. tripolium can take up and assimilate amino acids (alanine) and oligopeptides (trialanine), in addition to NH4+ and NO3−. In hydroponic solutions the uptake of alanine-N and trialanine-N was comparable to that of NO3−, but lower than NH4+. Comparison of the 13C and 15N ratios in the plant tissues suggested that at least 70% of the alanine and trialanine was taken up intact from solution. Plant capture of exogenously applied N by the soil-grown plants was much lower than in the hydroponically-grown plants. We ascribe this reduced rate of plant N uptake to increased microbial competition for DON, lower rates of N delivery to the root surface (from reduced mass flow and diffusion) and sorption of N solutes to the solid matrix. 14C-labelled amino acid and peptides indicated rapid assimilation of the DON once taken up by the plants. Our results strongly suggest that hydroponically grown S. europaea and A. tripolium are capable of taking up DON at high rates showing that it is highly pertinent to consider DON removal in the phytoremediation of wastewater. In addition, this is the first indication of direct peptide uptake by halophytic plants. We conclude that halophytes have evolved the capacity to take up a wide range of N compounds to satisfy their N demand when growing in N-limiting saltmarsh environments and that this intrinsic potential can be harnessed for wastewater treatment.

International audience; The quantification of sources and sinks of carbon from land use and land cover changes (LULCC) is uncertain. We investigated how the parametrization of LULCC and of organic matter decomposition, as well as initial land cover, affects the historical and future carbon fluxes in an Earth System Model (ESM). Using the land component of the Max Planck Institute ESM, we found that the historical (1750-2010) LULCC flux varied up to 25% depending on the fraction of biomass which enters the atmosphere directly due to burning or is used in short-lived products. The uncertainty in the decadal LULCC fluxes of the recent past due to the parametrization of decomposition and direct emissions was 0.6 Pg C yr −1 , which is 3 times larger than the uncertainty previously attributed to model and method in general. Preindustrial natural land cover had a larger effect on decadal LULCC fluxes than the aforementioned parameter sensitivity (1.0 Pg C yr −1). Regional differences between reconstructed and dynamically computed land covers, in particular, at low latitudes, led to differences in historical LULCC emissions of 84-114 Pg C, globally. This effect is larger than the effects of forest regrowth, shifting cultivation, or climate feedbacks and comparable to the effect of differences among studies in the terminology of LULCC. In general, we find that the practice of calibrating the net land carbon balance to provide realistic boundary conditions for the climate component of an ESM hampers the applicability of the land component outside its primary field of application.

Considering the combined effects of CO2 fertilization and climate change drivers on plant physiology leads to a modest increase in simulated European forest transpiration in spite of the effects of CO2-induced stomatal closure. The Earth’s carbon and hydrologic cycles are intimately coupled by gas exchange through plant stomata1,2,3. However, uncertainties in the magnitude4,5,6 and consequences7,8 of the physiological responses9,10 of plants to elevated CO2 in natural environments hinders modelling of terrestrial water cycling and carbon storage11. Here we use annually resolved long-term δ13C tree-ring measurements across a European forest network to reconstruct the physiologically driven response of intercellular CO2 (Ci) caused by atmospheric CO2 (Ca) trends. When removing meteorological signals from the δ13C measurements, we find that trees across Europe regulated gas exchange so that for one ppmv atmospheric CO2 increase, Ci increased by ∼0.76 ppmv, most consistent with moderate control towards a constant Ci/Ca ratio. This response corresponds to twentieth-century intrinsic water-use efficiency (iWUE) increases of 14 ± 10 and 22 ± 6% at broadleaf and coniferous sites, respectively. An ensemble of process-based global vegetation models shows similar CO2 effects on iWUE trends. Yet, when operating these models with climate drivers reintroduced, despite decreased stomatal opening, 5% increases in European forest transpiration are calculated over the twentieth century. This counterintuitive result arises from lengthened growing seasons, enhanced evaporative demand in a warming climate, and increased leaf area, which together oppose effects of CO2-induced stomatal closure. Our study questions changes to the hydrological cycle, such as reductions in transpiration and air humidity, hypothesized to result from plant responses to anthropogenic emissions.

Human activities disturb the biogeochemical cycles often resulting in limited eco-system services. The cycles of biologically active elements are also coupled to each other which is rarely acknowledged in ecosystem studies. Many of the regulating and maintenance services are linked to element cycles driven by micro-organisms, but these have often been omitted in ecosystem service studies. In the present publication the terminology of ecosystem services are used to help to define and describe the coupled biogeochemical processes and to highlight their importance in both terrestrial and aquatic ecosystems. The extended abstracts offer fresh viewpoints on biogeochemical cycles and on the management of their fluxes. The abstracts may also function as basis for new themes for research.

Nitrogen (N) and phosphorus (P) are essential elements for all living organisms. However, in excess, they contribute to several environmental problems such as aquatic and terrestrial eutrophication. Globally, human action has multiplied the volume of N and P cycling since the onset of industrialization. The multiplication is a result of intensified agriculture, increased energy consumption and population growth. Industrial ecology (IE) is a discipline, in which human interaction with the ecosystems is investigated using a systems analytical approach. The main idea behind IE is that industrial systems resemble ecosystems, and, like them, industrial systems can then be described using material, energy and information flows and stocks. Industrial systems are dependent on the resources provided by the biosphere, and these two cannot be separated from each other. When studying substance flows, the aims of the research from the viewpoint of IE can be, for instance, to elucidate the ways how the cycles of a certain substance could be more closed and how the flows of a certain substance could be decreased per unit of production (= dematerialization). In Finland, N and P are studied widely in different ecosystems and environmental emissions. A holistic picture comparing different societal systems is, however, lacking. In this thesis, flows of N and P were examined in Finland using substance flow analysis (SFA) in the following four subsystems: I) forest industry and use of wood fuels, II) food production and consumption, III) energy, and IV) municipal waste. A detailed analysis at the end of the 1990s was performed. Furthermore, historical development of the N and P flows was investigated in the energy system (III) and the municipal waste system (IV). The main research sources were official statistics, literature, monitoring data, and expert knowledge. The aim was to identify and quantify the main flows of N and P in Finland in the four subsystems studied. Furthermore, the aim was to elucidate whether the nutrient systems are cyclic or linear, and to identify how these systems could be more efficient in the use and cycling of N and P. A final aim was to discuss how this type of an analysis can be used to support decision-making on environmental problems and solutions. Of the four subsystems, the food production and consumption system and the energy system created the largest N flows in Finland. For the creation of P flows, the food production and consumption system (Paper II) was clearly the largest, followed by the forest industry and use of wood fuels and the energy system. The contribution of Finland to N and P flows on a global scale is low, but when compared on a per capita basis, we are one of the largest producers of these flows, with relatively high energy and meat consumption being the main reasons. Analysis revealed the openness of all four systems. The openness is due to the high degree of internationality of the Finnish markets, the large-scale use of synthetic fertilizers and energy resources and the low recycling rate of many waste fractions. Reduction in the use of fuels and synthetic fertilizers, reorganization of the structure of energy production, reduced human intake of nutrients and technological development are crucial in diminishing the N and P flows. To enhance nutrient recycling and replace inorganic fertilizers, recycling of such wastes as wood ash and sludge could be promoted. SFA is not usually sufficiently detailed to allow specific recommendations for decision-making to be made, but it does yield useful information about the relative magnitude of the flows and may reveal unexpected losses. Sustainable development is a widely accepted target for all human action. SFA is one method that can help to analyse how effective different efforts are in leading to a more sustainable society. SFA's strength is that it allows a holistic picture of different natural and societal systems to be drawn. Furthermore, when the environmental impact of a certain flow is known, the method can be used to prioritize environmental policy efforts. Typpi (N) ja fosfori (P) ovat elintärkeitä alkuaineita kaikille olioille. Liiallisissa määrin ympäristössä ne kuitenkin aiheuttavat monia ongelmia kuten vesistöjen ja maaperän rehevöitymistä. On arvioitu, että maailmanlaajuisessa mittakaavassa ihmistoiminta on moninkertaistanut typen ja fosforin kiertomäärän ja -nopeuden teollistumisesta alkaen. Pääasiallisina syinä ovat maatalouden tehostuminen, energiankäytön lisääntyminen ja väestömäärän kasvu. Teollisessa ekologiassa ihmisten vuorovaikutusta ekosysteemien kanssa tarkastellaan systeemianalyyttisen lähestymistavan avulla. Teollisen ekologian perusajatus on, että teolliset järjestelmät muistuttavat ekosysteemeitä, ja niitä voidaan näin ollen kuvata materiaali-, energia- ja tietovirtojen ja varantojen avulla. Teolliset järjestelmät ovat riippuvaisia biosfäärin tarjoamista resursseista, eikä näitä kahta voida erottaa toistaan. Kun tutkitaan ainevirtoja, on teollisen ekologian näkökulmasta tavoitteena muun muassa etsiä ja havainnollistaa tapoja, kuinka tietyn aineen kierto voisi olla entistä suljetumpi. Lisäksi voidaan tutkia esimerkiksi dematerialisaatiota eli sitä, miten tietyn yhdisteen virtoja voitaisiin pienentää tuotettuun määrään verrattuna. Suomessa typpeä ja fosforia sekä niiden käyttäytymistä, kiertoa ja vaikutuksia on tutkittu kattavasti eri ekosysteemeissä. Lisäksi päästöjä ympäristöön on selvitetty paljon. Kattava kokonaiskuva, joka vertailee typpeä ja fosforia eri yhteiskunnallisissa järjestelmissä, on kuitenkin puuttunut. Tässä tutkimuksessa typen ja fosforin virtoja tarkasteltiin ainevirta-analyysilla neljässä järjestelmässä: I) metsäteollisuus ja puupolttoaineiden käyttö, II) ruoan tuotanto ja kulutus, III) energia ja IV) yhdyskuntajätteet. Näistä tehtiin yksityiskohtainen 1990-luvun loppua koskeva analyysi. Lisäksi typen ja fosforin virtojen historiallista kehitystä tutkittiin energiajärjestelmässä (III) ja yhdyskuntajätejärjestelmässä (IV). Pääasialliset tietolähteet olivat viralliset tilastot, kirjallisuus, päästöjen tarkkailuaineisto ja asiantuntija-arviot. Tutkimuksen tarkoituksena oli tunnistaa tärkeimmät typen ja fosforin virrat neljässä järjestelmässä Suomessa sekä laskea virtojen suuruus. Lisäksi tarkoituksena oli tarkastella, ovatko kyseisten järjestelmien typpi- ja fosforivirrat suljettuja vai avoimia sekä löytää tapoja, kuinka typen ja fosforin käyttöä ja kiertoa voitaisiin tehostaa. Tavoitteena oli myös pohtia, kuinka hyvin ainevirta-analyysi soveltuu ympäristöongelmia ja niiden ratkaisuja koskevan päätöksenteon tueksi. Tarkastelluista neljästä järjestelmästä ruoan tuotanto ja kulutus ja energiajärjestelmä tuottivat suurimmat typen virrat. Fosforin virtojen aiheuttajana ruoan tuotanto ja kulutus oli merkittävin. Suomen merkitys maailmanlaajuiseen ravinnekiertoon on vähäinen, mutta asukasmäärään suhteutettuna Suomi on yksi merkittävämpiä typpi- ja fosforivirtojen aiheuttajia. Syitä ovat suhteellisen korkea energian- ja lihankulutus. Tutkimus osoitti kaikkien neljän systeemin avoimuuden, mikä johtuu suomalaisen kaupan kansainvälisyydestä, keinolannoitteiden mittavasta käytöstä, suhteellisen suuresta energiankulutuksesta ja monien jätejakeiden alhaisesta kierrätysasteesta. Polttoaineiden ja keinolannoitteiden käytön vähentäminen, energiantuotantorakenteen uudistaminen, ihmisten ravinteiden kulutuksen (ruoassa) vähentäminen ja teknologinen kehitys ovat olennaisia keinoja pienentää typpi- ja fosforivirtoja. Puutuhkan ja lietteen kierrätyksen avulla voitaisiin edistää ravinnekiertojen sulkeutumista ja korvata keinolannoitteita. Ainevirta-analyysi ei ole yleensä riittävän tarkka menetelmä tuottaakseen yksityiskohtaisia johtopäätöksiä päätöksentekijöille. Sen avulla voidaan tuottaa käyttökelpoista tietoa eri virtojen suhteellisista osuuksista ja se voi myös paljastaa odottamattomia aineiden hävikkejä. Kestävyys on yleisesti hyväksytty tavoite kaikessa ihmistoiminnassa. Ainevirta-analyysi on yksi menetelmä, jonka avulla voidaan tarkastella tapoja, miten kohti kestävämpää yhteiskuntaa päästään. Ainevirta-analyysin vahvuutena on, että sen avulla voidaan tuottaa kokonaiskuva eri luonnon- ja yhteiskunnan järjestelmistä. Kun lisäksi kunkin virran ympäristövaikutus tiedetään, menetelmää voidaan käyttää ympäristöpoliittisten toimenpiteiden priorisointiin

Methane (CH4) exchange in tree stems and canopies and the processes involved are among the least understood components of the global CH4 cycle. Recent studies have focused on quantifying tree stems as sources of CH4 and understanding abiotic CH4 emissions in plant canopies, with the role of microbial in situ CH4 formation receiving less attention. Moreover, despite initial reports revealing CH4 consumption, studies have not adequately evaluated the potential of microbial CH4 oxidation within trees. In this paper, we discuss the current level of understanding on these processes. Further, we demonstrate the potential of novel metagenomic tools in revealing the involvement of microbes in the CH4 exchange of plants, and particularly in boreal trees. We detected CH4 producing methanogens and novel monooxygenases, potentially involved in CH4 consumption, in coniferous plants. In addition, our field flux measurements from Norway spruce (Picea abies) canopies demonstrate both net CH4 emissions and uptake, giving further evidence that both production and consumption are relevant to the net CH4 exchange. Our findings, together with the emerging diversity of novel CH4 producing microbial groups, strongly suggest microbial analyses should be integrated in the studies aiming to reveal the processes and drivers behind plant CH4 exchange. peerReviewed