Browsing by Subject "organic carbon"

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  • Cano Bernal, José Enrique; Rankinen, Katri; Thielking, Sophia (Academic Press., 2022)
    Journal of Environmental Management
    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.
  • Kivilä, E. Henriikka; Luoto, Tomi P.; Rantala, Marttiina V.; Kiljunen, Mikko; Rautio, Milla; Nevalainen, Liisa (2019)
    Climate warming and consequent greening of subarctic landscapes increase the availability of organic carbon to the detrital food webs in aquatic ecosystems. This may cause important shifts in ecosystem functioning through the functional feeding patterns of benthic organisms that rely differently on climatically altered carbon resources. Twenty-five subarctic lakes in Finnish Lapland across a tree line ecotone were analysed for limnological and optical variables, carbon (delta C-13) and nitrogen (delta N-15) stable isotope (SI) composition of surface sediment organic matter (OM) and fossil Chironomidae (Diptera) remains to examine environmental controls behind chironomid functional feeding group (FFG) structure and their isotopic associations for assessing ecosystem functioning and carbon utilisation. We hypothesise that the chironomid SI signatures reflect increased allochthony with increasing allochthonous input, but the resource use may be altered by the functional characteristics of the assemblage. Multivariate analyses indicated that carbon geochemistry in the sediments (delta C-13, delta N-15, C/N), nutrients, indices of productivity (chlorophyll-a) and lake water optical properties, related to increasing presence of OM, played a key role in defining the chironomid FFG composition and isotopic signatures. Response modelling was used to examine how individual FFGs respond to environmental gradients. They showed divergent responses for OM quantity, dissolved organic carbon and nutrients between feeding strategies, suggesting that detritivores and filter feeders prefer contrasting carbon and nutrient conditions, and may thus hold paleoecological indicator potential to identify changes between different carbon fluxes. Benthic production was the primary carbon source for the chironomid assemblages according to a three-source SI mixing model, whereas pelagic and terrestrial components contributed less. Between-lake variability in source utilisation was high and controlled primarily by allochthonous OM inputs. Combination of biogeochemical modelling and functional classification is useful to widen our understanding of subarctic lake ecosystem functions and responses to climate-driven changes in limnology and catchment characteristics for long-term environmental change assessments and functional paleoecology.
  • Jauhiainen, Jyrki; Page, Susan E.; Vasander, Harri (2016)
    Agricultural and other land uses on ombrotrophic lowland tropical peat swamps typically lead to reduced vegetation biomass and water table drawdown. We review what is known about greenhouse gas (GHG) dynamics in natural and degraded tropical peat systems in south-east Asia, and on this basis consider what can be expected in terms of GHG dynamics under restored conditions. Only limited in situ data are available on the effects of restoration and the consequences for peat carbon (C) dynamics. Hydrological restoration seeks to bring the water table closer to the peat surface and thus re-create near-natural water table conditions, in order to reduce wildfire risk and associated fire impacts on the peat C store, as well as to reduce aerobic peat decomposition rates. However, zero emissions are unlikely to be achieved due to the notable potential for carbon dioxide (CO2) production from anaerobic peat decomposition processes. Increased vegetation cover (ideally woody plants) resulting from restoration will increase shading and reduce peat surface temperatures, and this may in turn reduce aerobic decomposition rates. An increase in litter deposition rate will compensate for C losses by peat decomposition but also increase the supply of labile C, which may prime decomposition, especially in peat enriched with recalcitrant substrates. The response of tropical peatland GHG emissions to peatland restoration will also vary according to previous land use and land use intensity.
  • Broman, Elias; Bonaglia, Stefano; Norkko, Alf; Creer, Simon; Nascimento, Francisco J. A. (2021)
    Benthic macrofauna is regularly used in monitoring programmes, however the vast majority of benthic eukaryotic biodiversity lies mostly in microscopic organisms, such as meiofauna (invertebrates <1 mm) and protists, that rapidly responds to environmental change. These communities have traditionally been hard to sample and handle in the laboratory, but DNA sequencing has made such work less time consuming. While DNA sequencing captures both alive and dead organisms, environmental RNA (eRNA) better targets living organisms or organisms of recent origin in the environment. Here, we assessed the biodiversity of three known bioindicator microeukaryote groups (nematodes, foraminifera, and ciliates) in sediment samples collected at seven coastal sites along an organic carbon (OC) gradient. We aimed to investigate if eRNA shotgun sequencing can be used to simultaneously detect differences in (i) biodiversity of multiple microeukaryotic communities; and (ii) functional feeding traits of nematodes. Results showed that biodiversity was lower for nematodes and foraminifera in high OC (6.2%-6.9%), when compared to low OC sediments (1.2%-2.8%). Dissimilarity in community composition increased for all three groups between Low OC and High OC, as well as the classified feeding type of nematode genera (with more nonselective deposit feeders in high OC sediment). High relative abundant genera included nematodeSabatieriaand foraminiferaElphidiumin high OC, andCryptocaryon-like ciliates in low OC sediments. Considering that future sequencing technologies are likely to decrease in cost, the use of eRNA shotgun sequencing to assess biodiversity of benthic microeukaryotes could be a powerful tool in recurring monitoring programmes.
  • Mao, Zhun; Derrien, Delphine; Didion, Markus; Liski, Jari; Eglin, Thomas; Nicolas, Manuel; Jonard, Mathieu; Saint-André, Laurent (Copernicus, 2019)
    In a context of global changes, modeling and predicting the dynamics of soil carbon stocks (CSs) in forest ecosystems are vital but challenging. Yasso07 is considered to be one of the most promising models for such a purpose. We examine the accuracy of its prediction of soil carbon dynamics over the whole French metropolitan territory at a decennial timescale. We used data from 101 sites in the RENECOFOR network, which encompasses most of the French temperate forests. These data include (i) the quantity of above-ground litterfall from 1994 to 2008, measured yearly, and (ii) the soil CSs measured twice at an interval of approximately 15 years (once in the early 1990s and around 2010). We used Yasso07 to simulate the annual changes in carbon stocks (ACCs; in tC ha−1 yr−1) for each site and then compared the estimates with actual recorded data. We carried out meta-analyses to reveal the variability in litter biochemistry in different tree organs for conifers and broadleaves. We also performed sensitivity analyses to explore Yasso07's sensitivity to annual litter inputs and model initialization settings. At the national level, the simulated ACCs (+0.00±0.07 tC ha−1 yr−1, mean ± SE) were of the same order of magnitude as the observed ones (+0.34±0.06 tC ha−1 yr−1). However, the correlation between predicted and measured ACCs remained weak (R2<0.1). There was significant overestimation for broadleaved stands and underestimation for coniferous sites. Sensitivity analyses showed that the final estimated CS was strongly affected by settings in the model initialization, including litter and soil carbon quantity and quality and also by simulation length. Carbon quality set with the partial steady-state assumption gave a better fit than the model with the complete steady-state assumption. With Yasso07 as the support model, we showed that there is currently a bottleneck in soil carbon modeling and prediction due to a lack of knowledge or data on soil carbon quality and fine-root quantity in the litter.
  • Sarkala, Tero (Helsingin yliopisto, 2019)
    Tiivistelmä * Referat * Abstract Tutkimuksessa selvitettiin maan muokkausmenetelmien vaikutusta savimaalla. Tutkimus tehtiin Yara Suomen koetilalla Vihdissä. Siellä vuodesta 2007 käynnissä olleiden yhtäjaksoisten muokkauskokeiden jatkoksi haluttiin selvittää, miten muokkausmenetelmät ovat vaikuttaneet maahan. Kokeessa tutkittiin suorakylvetyn, sänkimuokatun ja kynnetyn maan eroja. Tutkimuksessa selvitettiin maan rakenteeseen liittyviä ominaisuuksia: maan kosteus keväällä, penetrometri läpäisevyys, lierojen kekolaskenta, maan orgaanisen hiilen pitoisuus, maan ravinneanalyysit sekä Peltomaan laatutesti. Mittaukset ja määritykset tehtiin kasvukauden 2015 aikana. Kokeista selvisi, että pitkäaikaiset muutokset muokkauksessa vaikuttivat maahan erilaisesti. Penetrometri mittauksissa kävi ilmi, että kynnetyn maan työntövastus oli pienin 0–25 cm syvyydessä, josta syvemmälle mentäessä kaikkien muokkaustapojen työntövastus oli lähes sama. Maan orgaanisen hiilen pitoisuus? 0–15 cm syvyydessä oli kevennetyillä muokkaustavoilla 26 % suurempi kuin kynnetyllä. Maan kosteus keväällä oli suorakylvetyssä maassa suurin ja kynnetyssä pienin. Lierolaskennassa kävi ilmi, että kynnetyllä maalla oli kekoja vähemmän kuin muissa muokkauksissa. Maan ravinneanalyyseissä ei löytynyt merkitsevää eroa eri muokkaustapojen välillä. Peltomaan laatutestissä tutkittiin maan ominaisuuksia fysikaalisesti ja biologisesti. Peltomaan laatutestin perusteella pintamaan vedenjohtavuus on kaikilla mailla hyvä, suorakylvetystä maasta ei löydy tiivistymää ja siinä on eniten lieroja. Lopuksi todettiin, että tämän tutkimuksen mukaan ei voida päätellä, mikä muokkaustavoista olisi paras savimaalla pohjoisissa olosuhteissa. Kuitenkin tutkimus viittaa siihen että, pitkään jatkunut suorakylvö saattaisi olla hyvä vaihtoehto savimaan viljelyssä.
  • Ekholm, Petri; Ollikainen, Markku; Ala-Harja, Venla; Begum, Khaleda; Huttunen, Markus; Järvenranta, Kirsi; Kiirikki, Mikko; Kuosa, Harri; Lötjönen, Sanna; Riihimäki, Juha; Taskinen, Antti; Tikkanen, Tommi Petteri; Yli-Halla, Markku (Suomen ympäristökeskus, 2022)
    Suomen ympäristökeskuksen raportteja
  • Johannesdottir, Solveig L.; Kärrman, Erik; Barquet, Karina; Koskiaho, Jari; Olsson, Olle; Giełczewski, Marek (Elsevier, 2021)
    Cleaner Environmental Systems 2: 100030
    Sustainability assessments can be a powerful tool in decision-making regarding technical innovations. In this study, a sustainability assessment of technical systems for recovering nutrients and carbon from domestic wastewater is presented. Multi-criteria analysis was used to calculate a sustainability score of three different technical systems compared to a baseline in two case-studies: the Fyriså river catchment in Sweden and the Słupia river catchment in Poland. Two participatory workshops with local stakeholders were held in each case-study, the first to co-develop the system alternatives and sustainability criteria and the second to collect stakeholder weighting of the criteria. Although the systems assessed in both case studies were similar, the resulting sustainability scores were different. In Fyris, although the differences in scores was small, the preferred alternative was introduction of source-separation followed by a large redesign of the treatment and phosphorus extraction from incinerated sludge was the least sustainable alternative. For the Słupia systems the scores varied more, and the preferred system was a large redesign of the wastewater treatment followed by ammonia stripping of the reject water and the source-separation alternative received the lowest score. In both case-studies, the more costly system received highest sustainability score indicating the large potential benefits of enhancing resource recovery from domestic wastewater. Stakeholders did not prioritize technical aspects over the other sustainability criteria, yet most of research on resource recovery interventions is focused on technical performance.