Suomen ympäristökeskus - Julkaisuarkisto: Recent submissions

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  • Västilä, Kaisa; Väisänen, Sari; Koskiaho, Jari; Lehtoranta, Virpi; Karttunen, Krister; Kuussaari, Mikko; Järvelä, Juha; Koikkalainen, Kauko (MDPI, 2021)
    Sustainability 13, 16
    Conventional dredging of ditches and streams to ensure agricultural drainage and flood mitigation can have severe environmental impacts. The aim of this paper is to investigate the potential benefits of an alternative, nature-based two-stage channel (TSC) design with floodplains excavated along the main channel. Through a literature survey, investigations at Finnish field sites and expert interviews, we assessed the performance, costs, and monetary environmental benefits of TSCs in comparison to conventional dredging, as well as the bottlenecks in their financing and governance. We found evidence supporting the expected longer-term functioning of drainage as well as larger plant and fish biodiversity in TSCs compared to conventional dredging. The TSC design likely improves water quality since the floodplains retain suspended sediment and phosphorus and remove nitrogen. In the investigated case, the additional value of phosphorus retention and conservation of protected species through the TSC design was 2.4 times higher than the total costs. We demonstrate how TSCs can be made eligible for the obligatory vegetated riparian buffer of the European Union agri-environmental subsidy scheme (CAP-AES) by optimising their spatial application with respect to other buffer measures, and recommend to publicly finance their additional costs compared to conventional dredging at priority sites. Further studies on biodiversity impacts and long-term performance of two-stage channels are required.
  • Bhattacharjee, Joy; Rabbil, Mehedi; Fazel, Nasim; Darabi, Hamid; Choubin, Bahram; Khan, Md. Motiur Rahman; Marttila, Hannu; Haghighi, Ali Torabi (Elsevier, 2021)
    Science of the Total Environment 797 (2021), 149034
    Lake water level fluctuation is a function of hydro-meteorological components, namely input, and output to the system. The combination of these components from in-situ and remote sensing sources has been used in this study to define multiple scenarios, which are the major explanatory pathways to assess lake water levels. The goal is to analyze each scenario through the application of the water balance equation to simulate lake water levels. The largest lake in Iran, Lake Urmia, has been selected in this study as it needs a great deal of attention in terms of water management issues. We ran a monthly water balance simulation of nineteen scenarios for Lake Urmia from 2003 to 2007 by applying different combinations of data, including observed and remotely sensed water level, flow, evaporation, and rainfall. We used readily available water level data from Hydrosat, Hydroweb, and DAHITI platforms; evapotranspiration from MODIS and rainfall from TRMM. The analysis suggests that the consideration of field data in the algorithm as the initial water level can reproduce the fluctuation of Lake Urmia water level in the best way. The scenario that combines in-situ meteorological components is the closest match to the observed water level of Lake Urmia. Almost all scenarios showed good dynamics with the field water level, but we found that nine out of nineteen scenarios did not vary significantly in terms of dynamics. The results also reveal that, even without any field data, the proposed scenario, which consists entirely of remote sensing components, is capable of estimating water level fluctuation in a lake. The analysis also explains the necessity of using proper data sources to act on water regulations and managerial decisions to understand the temporal phenomenon not only for Lake Urmia but also for other lakes in semi-arid regions.
  • de Wit, Heleen A.; Lepistö, Ahti; Marttila, Hannu; Wenng, Hannah; Bechmann, Marianne; Blicher-Mathiesen, Gitte; Eklöf, Karin; Futter, Martyn N.; Kortelainen, Pirkko; Kronvang, Brian; Kyllmar, Katarina; Rakovic, Jelena (Wiley, 2020)
    Hydrological Processes 34, 25 (2020)
    Agricultural, forestry-impacted and natural catchments are all vectors of nutrient loading in the Nordic countries. Here, we present concentrations and fluxes of total nitrogen (totN) and phosphorus (totP) from 69 Nordic headwater catchments (Denmark: 12, Finland:18, Norway:17, Sweden:22) between 2000 and 2018. Catchments span the range of Nordic climatic and environmental conditions and include natural sites and sites impacted by agricultural and forest management. Concentrations and fluxes of totN and totP were highest in agricultural catchments, intermediate in forestry-impacted and lowest in natural catchments, and were positively related %agricultural land cover and summer temperature. Summer temperature may be a proxy for terrestrial productivity, while %agricultural land cover might be a proxy for catchment nutrient inputs. A regional trend analysis showed significant declines in N concentrations and export across agricultural (−15 μg totN L−1 year−1) and natural (−0.4 μg NO3-N L−1 year−1) catchments, but individual sites displayed few long-term trends in concentrations (totN: 22%, totP: 25%) or export (totN: 6%, totP: 9%). Forestry-impacted sites had a significant decline in totP (−0.1 μg P L−1 year−1). A small but significant increase in totP fluxes (+0.4 kg P km−2 year−1) from agricultural catchments was found, and countries showed contrasting patterns. Trends in annual concentrations and fluxes of totP and totN could not be explained in a straightforward way by changes in runoff or climate. Explanations for the totN decline include national mitigation measures in agriculture international policy to reduced air pollution and, possibly, large-scale increases in forest growth. Mitigation to reduce phosphorus appears to be more challenging than for nitrogen. If the green shift entails intensification of agricultural and forest production, new challenges for protection of water quality will emerge possible exacerbated by climate change. Further analysis of headwater totN and totP export should include seasonal trends, aquatic nutrient species and a focus on catchment nutrient inputs.
  • Laine, Valtteri; Goerlandt, Floris; Banda, Osiris Valdez; Baldauf, Michael; Koldenhof, Yvonne; Rytkönen, Jorma (Elsevier, 2021)
    Marine Pollution Bulletin 171 (2021), 112724
    Several risk management frameworks have been introduced in the literature for maritime Pollution Preparedness and Response (PPR). However, in light of the actual needs of the competent authorities, there is still a lack of framework that is established on a sound risk conceptual basis, addresses the different risk management decision-making contexts of organizations, and provides tools for various risk management questions of this field. To alleviate the limits of existing approaches, this paper introduces a new risk management framework for this purpose, which was developed in cooperation with the competent authorities and other maritime experts. The framework adopts the risk-informed decision-making strategy and includes three aligned components. The first component provides a unified theoretical risk concept to the framework through an interpretation of the Society for Risk Analysis risk approach. The second consists of four ISO 31000:2018 standard based processes focused on different risk management decision-making contexts of the PPR organizations. The third comprises a set of practical risk assessment tools to generate the needed information. A case study provides an example of the functionality of this framework with integrated data from the northern Baltic Sea. To conclude, a risk concept is provided for the PPR authorities and their stakeholders as well as processes for managing the risk and tools for its assessment.
  • Albrecht, Moritz; Lukkarinen, Jani (Sage journals, 2020)
    Environment Planning C: Politics and Space 2020; 38 (7-8): 1465-1483
    The blue bioeconomy is gaining momentum in EU policy debate and various national government strategies as a pathway towards a more sustainable society. Linked to the circularity of economic processes, it combines the promise of (regional) economic development with a sustainable, bio-based transition focused on increased and novel utilisation of aquatic resources. Nonetheless, portrayed as a holistic approach, the political visions of blue bioeconomy reside predominantly in marine environments with little integration of freshwater perspectives or alternative development paths. Rooted in concepts of policy mobility, assembling processes and the positionalities of involved entities, this paper displays two regionally embedded blue bioeconomy developments – Norwegian coastal seaweed farming and Finnish lake fisheries – and their spatially diverse reconnections with national and international policy narratives. By framing a freshwater and a coastal marine case, and their spatial reconnections with an overarching yet diversely translated policy realm, the paper taps into the multiple ontologies of water in blue bioeconomy governance and presents initial empirical and methodological steps towards a relational understanding of its governance processes. Based on four key topical reconnections, the article points to a variety of challenging mismatches between policy narratives, local development processes and potentials. It also suggests conceptual and methodological implications of this approach for further research into “blue” resource governance
  • Pilla, Rachel M.; Williamson, Graig E.; Adamovich, Boris V.; Adrian, Rita; Anneville, Orlane; Chandra, Sudeep; Colom-Montero, William; Devlin, Shawn P.; Dix, Margaret A; Dokulil, Martin T.; Gaiser, Evelyn E.; Girdner, Scott F.; Hambright, David K.; Hamilton, David P.; Havens, Karl; Hessen, Dag O.; Higgins, Scott N.; Huttula, Timo H.; Huuskonen, Hannu; Isles, Peter D. F.; Joehnk, Klaus D.; Jones, Ian D.; Keller, Wendel Bill; Knoll, Lesley B.; Korhonen, Johanna; Kraemer, Benjamin M.; Leavitt, Peter R.; Lepori, Fabio; Luger, Martin S.; Maberly, Stephen C.; Melack, John M.; Melles, Stephanie J.; Müller-Navarra, Dörthe C.; Pierson, Don C.; Pislegina, Helen V.; Plisnier, Pierre-Denis; Richardson, David C.; Rimmer, Alon; Rogora, Michela; Rusak, James A.; Sadro, Steven; Salmaso, Nico; Saros, Jasmine E.; Saulnier-Talbot, Émilie; Schindler, Daniel E.; Schmid, Martin; Shimaraeva, Svetlana V.; Silow, Eugene A.; Sitoki, Lewis M.; Sommaruga, Ruben; Straile, Dietmar; Strock, Kristin E.; Thiery, Wim; Timofeyev, Maxim A.; Verburg, Piet; Vinebrooke, Rolf D.; Weyhenmeyer, Gesa A.; Zadereev, Egor (Rebekah A. Canada, 2020)
    Scientific Reports 10, 1 (2020), 20514
    Globally, lake surface water temperatures have warmed rapidly relative to air temperatures, but changes in deepwater temperatures and vertical thermal structure are still largely unknown. We have compiled the most comprehensive data set to date of long-term (1970–2009) summertime vertical temperature profiles in lakes across the world to examine trends and drivers of whole-lake vertical thermal structure. We found significant increases in surface water temperatures across lakes at an average rate of + 0.37 °C decade−1, comparable to changes reported previously for other lakes, and similarly consistent trends of increasing water column stability (+ 0.08 kg m−3 decade−1). In contrast, however, deepwater temperature trends showed little change on average (+ 0.06 °C decade−1), but had high variability across lakes, with trends in individual lakes ranging from − 0.68 °C decade−1 to + 0.65 °C decade−1. The variability in deepwater temperature trends was not explained by trends in either surface water temperatures or thermal stability within lakes, and only 8.4% was explained by lake thermal region or local lake characteristics in a random forest analysis. These findings suggest that external drivers beyond our tested lake characteristics are important in explaining long-term trends in thermal structure, such as local to regional climate patterns or additional external anthropogenic influences.
  • Tolvanen, Anne; Saarimaa, Miia; Tuominen, Seppo; Aapala, Kaisu (Elsevier, 2020)
    Global Ecology and Conservation, 23 (2020), e01160
    We used habitat suitability modeling to investigate whether the 15% ecosystem restoration target set in the previous Convention of Biological Diversity (CBD) and EU Biodiversity strategy targets, is sufficient to safeguard red-listed mire plant species. We assessed six theoretical restoration scenarios for drained peatland landscapes by altering the proportion of drained and undrained peatland area in 25-ha grid cells. The proportions represented steps when 15%, 30%, 45%, 60%, 75% and 100% of the drained peatland is restored. We modelled the habitat suitability for 48 red-listed plant species in the aapa mire region in boreal Finland. Model outcomes were assessed at the level of five species groups: calcareous species, rich fen species, decaying wood species, mesotrophic fen species, and spruce swamp species. The predicted distribution increased for 34 (71%) of the 48 red-listed plant species when 15% of drained peatland area was predicted to be restored. At the same time the potentially occupied area of species increased by 9%. In the scenario where all peatlands were restored, the predicted distribution of 43 (90%) of species increased, and on average the distribution of species quadrupled. According to our predictions, meeting the 15% ecosystem restoration target, set in the previous CBD and EU Biodiversity strategy targets would be beneficial for most of the boreal red-listed mire plant species, but a larger restoration area would expand their distribution considerably more. Our study shows that a landscape level approach is important to assess thresholds for the potential biodiversity benefits arising from peatland restoration. The models can also be used to select suitable areas for restoration.
  • Koski, Vilja; Kotamäki, Niina; Hämäläinen, Heikki; Meissner, Kristian; Karvanen, Juha; Kärkkäinen, Salme (Elsevier, 2020)
    Science of the Total Environment 726 (2020), 138396
    Uncertainty in the information obtained through monitoring complicates decision making about aquatic ecosystems management actions. We suggest the value of information (VOI) to assess the profitability of paying for additional monitoring information, when taking into account the costs and benefits of monitoring and management actions, as well as associated uncertainty. Estimating the monetary value of the ecosystem needed for deriving VOI is challenging. Therefore, instead of considering a single value, we evaluate the sensitivity of VOI to varying monetary value. We also extend the VOI analysis to the more realistic context where additional information does not result in perfect, but rather in imperfect information on the true state of the environment. Therefore, we analytically derive the value of perfect information in the case of two alternative decisions and two states of uncertainty. Second, we describe a Monte Carlo type of approach to evaluate the value of imperfect information about a continuous classification variable. Third, we determine confidence intervals for the VOI with a percentile bootstrap method. Results for our case study on 144 Finnish lakes suggest that generally, the value of monitoring exceeds the cost. It is particularly profitable to monitor lakes that meet the quality standards a priori, to ascertain that expensive and unnecessary management can be avoided. The VOI analysis provides a novel tool for lake and other environmental managers to estimate the value of additional monitoring data for a particular, single case, e.g. a lake, when an additional benefit is attainable through remedial management actions.
  • Kunttu, Panu; Helo, Teppo; Kulju, Matti; Julkunen, Jari; Kotiranta, Heikki (Finnish Mycological Society, 2020)
    Karstenia Mycological Journal 58, 1 (2020)
    We contribute to the knowledge on the occurrences and distributions of both aphyllophoroid and heterobasidioid fungi in Finland. We present four species new to Finland, i.e. Helicogloea sebacea, Phanerochaete cremeo-ochracea, Steccherinum cremeoalbum, and Uncobasidium luteolum, as well as 46 new records (locations) of 34 rare or rarely collected species. Additionally, we report on 40 species considered new to a certain subzone of the boreal forest vegetation zone in Finland. These records contain notes on their substrata, and the ecology and distribution of nationally new species are briefly discussed.
  • Hashemi, Fatemeh; Pohle, Ina; Pullens, Johannes W. M; Tornbjerg, Henrik; Kyllmar, Katarina; Marttila, Hannu; Lepistö, Ahti; Klove, Bjorn; Futter, Martyn; Kronvang, Brian (MDPI, 2020)
    Water 12 6 (2020)
    Optimal nutrient pollution monitoring and management in catchments requires an in-depth understanding of spatial and temporal factors controlling nutrient dynamics. Such an understanding can potentially be obtained by analysing stream concentration–discharge (C-Q) relationships for hysteresis behaviours and export regimes. Here, a classification scheme including nine different C-Q types was applied to a total of 87 Nordic streams draining mini-catchments (0.1–65 km2). The classification applied is based on a combination of stream export behaviour (dilution, constant, enrichment) and hysteresis rotational pattern (clock-wise, no rotation, anti-clockwise). The scheme has been applied to an 8-year data series (2010–2017) from small streams in Denmark, Sweden, and Finland on daily discharge and discrete nutrient concentrations, including nitrate (NO3−), total organic N (TON), dissolved reactive phosphorus (DRP), and particulate phosphorus (PP). The dominant nutrient export regimes were enrichment for NO3− and constant for TON, DRP, and PP. Nutrient hysteresis patterns were primarily clockwise or no hysteresis. Similarities in types of C-Q relationships were investigated using Principal Component Analysis (PCA) considering effects of catchment size, land use, climate, and dominant soil type. The PCA analysis revealed that land use and air temperature were the dominant factors controlling nutrient C-Q types. Therefore, the nutrient export behaviour in streams draining Nordic mini-catchments seems to be dominantly controlled by their land use characteristics and, to a lesser extent, their climate.
  • Peña Queralta, Jorge; Taipalmaa, Jussi; Can Pullinen, Bilge; Sarker, Victor Kathan; Nguyen Gia, Tuan; Tenhunen, Hannu; Gabbouj, Moncef; Raitoharju, Jenni; Westerlund, Tomi (IEEExplore, 2020)
    IEEE Access 8
    Search and rescue (SAR) operations can take significant advantage from supporting autonomous or teleoperated robots and multi-robot systems. These can aid in mapping and situational assessment, monitoring and surveillance, establishing communication networks, or searching for victims. This paper provides a review of multi-robot systems supporting SAR operations, with system-level considerations and focusing on the algorithmic perspectives for multi-robot coordination and perception. This is, to the best of our knowledge, the first survey paper to cover (i) heterogeneous SAR robots in different environments, (ii) active perception in multi-robot systems, while (iii) giving two complementary points of view from the multi-agent perception and control perspectives. We also discuss the most significant open research questions: shared autonomy, sim-to-real transferability of existing methods, awareness of victims' conditions, coordination and interoperability in heterogeneous multi-robot systems, and active perception. The different topics in the survey are put in the context of the different challenges and constraints that various types of robots (ground, aerial, surface, or underwater) encounter in different SAR environments (maritime, urban, wilderness, or other post-disaster scenarios). The objective of this survey is to serve as an entry point to the various aspects of multi-robot SAR systems to researchers in both the machine learning and control fields by giving a global overview of the main approaches being taken in the SAR robotics area.
  • Simha, Prithvi; Karlsson, Caroline; Viskari, Eeva-Liisa; Malila, Riikka; Vinnerås, Björn (Frontiers Media S.A., 2020)
    Frontiers in Environmental Science 8, 11.9.2020
    Alkaline dehydration can treat human urine to produce a dry and nutrient-rich fertilizer. To evaluate the technology at pilot-scale, we built a prototype with capacity to treat 30 L urine d−1 and field tested it for the first time at a military training camp in Finland. We operated the system for 3 months and monitored the recovery of nutrients, end-product composition, physicochemical properties and energy consumption. Results revealed that the system received less urine than anticipated, but achieved high dehydration rates (30–40 L d−1m−2), recovered 30 ± 6% N, and yielded end-products with 1.4% N, 0.9% P, and 8.3% K. However, we demonstrated that the system had potential to recover nearly 70% N and produce fertilizers containing 13.2% N, 2.3% P, and 6.0% K, if it was operated at the design capacity. The energy demand for dehydrating urine was not optimized, but we suggested several ways of reducing it. We also discussed concerns surrounding non-essential heavy metals, salts, and micropollutants, and how they can be overcome to safely recycle urine. Lastly, we pointed out the research gaps that need to be addressed before the technology can be implemented at larger scale.
  • Lindberg, Henrik; Punttila, Pekka; Vanha-Majamaa, Ilkka (Springer, 2020)
    Ecological Processes 9, 4 (2020)
    Historically, wildfires have played an important role in forest dynamics in Fennoscandia. In Finland, the annually burned area has diminished in recent decades. This has led to a decline of fire-adapted habitat types and species, many of which have become red-listed. In Fennoscandia, there is a long tradition of silvicultural burnings to enhance tree regeneration. Recently, prescribed burnings have been modified for biodiversity goals following the recommendations that have emerged from ecological research. Prominent biodiversity gains can be obtained by combining sufficient retention levels with burnings. Consequently, burning and retention have been recommended by recent national red-list assessments, strategies, and forest-management guidelines, and they have been adopted in forest-certification standards in Finland. Contrary to these recommendations, the opposite development has taken place: (1) the ecological efficiency of the criterion concerning prescribed burning in the PEFC forest-certification standard has been impaired, (2) state funding to encourage private forest owners to apply prescribed burning was reduced significantly, and (3) prescribed burnings have been abandoned altogether in commercial state-owned forests. Traditional burnings with variable retention have also been partially replaced with burning of small retention-tree groups. This new method is less risky and cheaper, but its ecological benefits are questionable because small-sized fires produce much smaller areas of burned forest soil with less fire-affected wood than traditional silvicultural burnings. Generally, the widely accepted goal to increase burnings with retention appears difficult to achieve and would require stronger political will and economic support from the government. We identified several actions that could improve the weakened situation of fire-dependent biodiversity and recommend the following: (1) setting a clear goal and ensuring sufficient funding for the burnings—including restoration burnings in conservation areas—and targeting these to specific fire-continuum areas with sufficient retention to ensure the continuity of fire-affected habitats at landscape level; (2) renewing the current subsidizing policies to encourage private landowners to perform prescribed burnings in regeneration areas after final fellings, and to safeguard accidental forest-fire areas as set-asides; (3) renewing the current prescribed-burning criterion of the Finnish PEFC forest-certification standard with more ambitious ecological goals; and (4) re-introducing prescribed burnings in commercial state forests where management targets are under political steering.
  • Nieminen, Mika; Sarkkola, Sakari; Haahti, Kersti; Sallantaus, Tapani; Koskinen, Markku; Ojanen, Paavo (Suoseura, 2020)
    Suo - tutkimusartikkelit
    Viime vuosina julkaistujen tutkimusten mukaan metsäojitettujen soiden vesistö kuormituksen epäillään olevan moninkertaisesti aiemmin arvioitua suurempaa. Syynä tähän on se, että kuormitusta syntyy aiemmista käsityksistä poiketen silloinkin, kun ojitusalueilla ei ole vuosikausiin tehty mitään toimenpiteitä. Tässä työssä arvioitiin metsäojitusalueilta syntyvä vesistökuormitus ottamalla huomioon sekä tämä nykyisistä metsätaloustoimenpiteistä riippumaton ”ojituslisä” että kunnostusojituksen, lannoituksen ja hakkuiden aiheuttama kuormitus. Tehdyn arvion mukaan metsätaloudesta ojitetuilla soilla syntyy Suomessa vuosittain typpikuormitusta noin 8500 Mg ja fosforikuormi tusta 590 Mg. Kun ojituslisä otetaan huomioon, typpikuormitus on noin 18-kertainen ja fosforikuormitus 6–7-kertainen aiempiin vain eri toimenpiteiden kuormitukset huomioon ottaviin arvioihin verrattuna. Vesiensuojelun kannalta oleellista olisi selvittää, mitkä tekijät ojitusalueilla aiheuttavat ojituslisän muodossa tapahtuvaa pysyvää kuormitusta ja mitä tämän kuormituksen torjumiseksi on tehtävissä.
  • Turunen, Jarno; Muotka, Timo; Aroviita, Jukka (Springer Link, 2020)
    Hydrobiologia 847 2
    Forestry-related land use can cause increasing instream sedimentation, burying and eradicating stream bryophytes, with severe ecological consequences. However, there is limited understanding of the relative roles and overall importance of the two frequently co-occurring stressors, increased fine sediments and loss of bryophytes, to stream biodiversity and ecosystem functions. By using random forest modeling and partial dependence functions, we studied the relative importance of stream bryophytes and fine sediments to multiple biological endpoints (leaf-decaying fungi, diatom, bryophyte, and benthic macroinvertebrate communities; leaf decomposition) using field survey data from headwater streams. Stream bryophyte abundance and richness were negatively related to fine sediment cover, highlighting the detrimental effect of sedimentation on bryophytes. However, bryophyte abundance was consistently more important a determinant of variation in community composition than was fine sediment cover. Leaf decomposition was influenced by shredder abundance, water temperature and, to a lesser degree, stream size. Our results suggest that the loss of stream bryophytes due to increasing sedimentation, rather than fine sediments per se, seems to be the key factor affecting multiple biological responses. Enhancing the re-establishment of bryophyte stands could partly compensate for the negative impacts of sedimentation on bryophytes and, consequently, on several other components of boreal stream ecosystems.
  • Pitkänen, Kati; Hannonen, Olga; Toso, Stefania; Gallent, Nick; Hamiduddin, Iqbal; Halseth, Greg; Hall, Michael C.; Müller, Dieter K.; Treivish, Andrey; Nefedova, Tatiana (Matkailututkimus, 2020)
    Matkailututkimus 16, 2 (2020)
  • Alaranta, Joonas; Turunen, Topi (Oxford University Press, 2020)
    Journal of Environmental Law, Volume 33, Issue 1, March 2021, Pages 113–136
    This article discusses the regulation of ‘substances of concern’ in the circular economy (CE) in the European Union (EU). It analyses the tensions and obstacles that the present sectoral separation of waste, product and chemicals legislation sets for the development of the CE. We argue that in a longer term perspective the aim should be to erase the border between waste and chemicals regulation and create a single regime for the regulation of materials and their flow. However, the eventual aim of such non-toxic material circulation can be achieved only via precautious transitional measures that outweigh the costs and benefits of each material flow and set restrictions for the particular substances of concern. Regulatory actions addressing the risks posed by the substances of concern in the waste-based material flows are urgently needed. New measures are necessary to protect human health and the environment and to support the development of the markets for the secondary materials.
  • Salmi, Pauliina; Mäki, Anita; Mikkonen, Anu; Pupponen, Veli-Mikko; Vuorio, Kristiina; Tiirola, Marja (Suomen ympäristökeskus, 2021)
    Boreal Environment Research 26: 17-27
    The smaller the phytoplankton, the greater effort is required to distinguish individual cells by optics-based methods. Flow cytometry is widely applied in marine picophytoplankton research, but in freshwater research its role has remained minor. We compared epifluorescence microscopy and flow cytometry in assessing the composition, abundance and cell sizes of autofluorescent picophytoplankton in epilimnia of 46 Finnish lakes. Phycocyaninrich picocyanobacteria were the most dominant. The two methods yielded comparable total picophytoplankton abundances, but the determination of cell sizes, and thus total biomasses, were on average an order of magnitude higher in the microscopy results. However, flow cytometry yielded higher cell sizes when applied on small-celled cultured algae. Our study demonstrated that both epifluorescence microscopy and flow cytometry are useful methods in assessing abundances of phycocyanin-rich and phycoerythrin-rich picocyanobacteria and eukaryotic picophytoplankton in lakes. However, accurate determination of cell size and biomass remain challenges for microscopy and especially for flow cytometry.
  • Suominen, Tapio; Westerholm, Jan; Kalliola, Risto; Attila, Jenni (MDPI, 2021)
    Remote Sensing vol 13(11):2104
    Seawaters exhibit various types of cyclic and trend-like temporal alterations in their biological, physical, and chemical processes. Surface water dynamics may vary, for instance, when the timings, durations, or amplitudes of seasonal developments of water properties alter between years and locations. We introduce a workflow using remote sensing to identify surface waters undergoing similar dynamics. The method, called ocean surface dynamics partitioning, classifies pixels based on their temporal change patterns instead of their properties at successive time snapshots. We apply an efficient parallel computing method to calculate Dynamic Time Warping (DTW) time series distances of large datasets of Earth Observation MERIS-instrument reflectance data Rrs(510 nm) and Rrs(620 nm), and produce a matrix of time series distances between 12,252 locations/time series in the Baltic Sea, for both wavelengths. We define cluster prototypes by hierarchical clustering of distance matrices and use them as initial prototypes for an iterative process of partitional clustering in order to identify areas that have similar reflectance dynamics. Lastly, we compute distances from the time series of the reflectance data to selected physical factors (wind, precipitation, and changes in sea surface temperature) obtained from Copernicus data archives. The workflow is reproducible and capable of managing large datasets in reasonable computation times and identifying areas of distinctive dynamics. The results show spatially coherent and logical areas without a priori information about the locations of the satellite image time series. The alignments of the reflectance time series vs. the observational time series of the physical environment clarify the causalities behind the cluster formation. We conclude that following the changes in an aquatic realm by biogeochemical observations at certain temporal intervals alone is not sufficient to identify environmental shifts. We foresee that the changes in dynamics are a sensitive measure of environmental threats and therefore they will be important to follow in the future.