Summer greenhouse gas fluxes in different types of hemiboreal lakes

Lakes are considered important regulators of atmospheric greenhouse gases (GHG). We estimated late summer open water GHG fluxes in nine hemiboreal lakes in Estonia classified under different lake types according to the European Water Framework Directive (WFD). We also used the WFD typology to provide an improved estimate of the total GHG emission from all Estonian lakes with a gross surface area of 2204 km2 representing 45,227 km2 of hemiboreal landscapes (the territory of Estonia). The results demonstrate largely variable CO2 fluxes among the lake types with most active emissions from Alkalitrophic (Alk), Stratified Alkalitrophic (StratAlk), Dark Soft and with predominant binding in Coastal, Very Large, and Light Soft lakes. The CO2 fluxes correlated strongly with dissolved CO2 saturation (DCO2) values at the surface. Highest CH4 emissions were measured from the Coastal lake type, followed by Light Soft, StratAlk, and Alk types; Coastal, Light Soft, and StratAlk were emitting CH4 partly as bubbles. The only emitter of N2O was the Alk type. We measured weak binding of N2O in Dark Soft and Coastal lakes, while in all other studied lake types, the N2O fluxes were too small to be quantified. Diversely from the common viewpoint of lakes as net sources of both CO2 and CH4, it turns out from our results that at least in late summer, Estonian lakes are net sinks of both CO2 alone and the sum of CO2 and CH4. This is mainly caused by the predominant CO2 sink function of Lake Peipsi forming ¾ of the total lake area and showing negative net emissions even after considering the Global Warming Potential (GWP) of other GHGs. Still, by converting CH4 data into CO2 equivalents, the combined emission of all Estonian lakes (8 T C day−1 ) is turned strongly positive: 2720 T CO2 equivalents per day.This research was inspired by GLEON (Global Lake Ecological Observatory Network) and was funded by Estonian Research Council (PSG32, PUT1598, PSG10, PRG709, PRG1167 and ETF8486), the European Union H2020 WIDESPREAD (TREICLAKE 951963) and the Swiss Program “Enhancing public environmental monitoring capacities”.This research was inspired by GLEON (Global Lake Ecological Observatory Network) and was funded by Estonian Research Council (PSG32, PUT1598, PSG10, PRG709, PRG1167 and ETF8486), the European Union H2020 WIDESPREAD (TREICLAKE 951963) and the Swiss Program “Enhancing public environmental monitoring capacities”

A chlorophyll-a algorithm for Landsat-8 based on mixture density networks

Material suplementario disponible en:Retrieval of aquatic biogeochemical variables, such as the near-surface concentration of chlorophyll-a (Chla) in inland and coastal waters via remote observations, has long been regarded as a challenging task. This manuscript applies Mixture Density Networks (MDN) that use the visible spectral bands available by the Operational Land Imager (OLI) aboard Landsat-8 to estimate Chla. We utilize a database of co-located in situ radiometric and Chla measurements (N = 4,354), referred to as Type A data, to train and test an MDN model (MDNA). This algorithm’s performance, having been proven for other satellite missions, is further evaluated against other widely used machine learning models (e.g., support vector machines), as well as other domain-specific solutions (OC3), and shown to offer significant advancements in the field. Our performance assessment using a held-out test data set suggests that a 49% (median) accuracy with near-zero bias can be achieved via the MDNA model, offering improvements of 20 to 100% in retrievals with respect to other models. The sensitivity of the MDNA model and benchmarking methods to uncertainties from atmospheric correction (AC) methods, is further quantified through a semi-global matchup dataset (N = 3,337), referred to as Type B data. To tackle the increased uncertainties, alternative MDN models (MDNB) are developed through various features of the Type B data (e.g., Rayleigh-corrected reflectance spectra ρs ). Using held-out data, along with spatial and temporal analyses, we demonstrate that these alternative models show promise in enhancing the retrieval accuracy adversely influenced by the AC process. Results lend support for the adoption of MDNB models for regional and potentially global processing of OLI imagery, until a more robust AC method is developed. Index Terms—Chlorophyll-a, coastal water, inland water, Landsat-8, machine learning, ocean color, aquatic remote sensing

Satellite-assisted monitoring of water quality to support the implementation of the Water Framework Directive

The EU Water Framework Directive1 (WFD) is an ambitious legislation framework to achieve good ecological and chemical status for all surface waters and good quantitative and chemical status for groundwater by 2027. A total of 111,062 surface waterbodies are presently reported on under the Directive, 46% of which are actively monitored for ecological status. Of these waterbodies 80% are rivers, 16% are lakes, and 4% are coastal and transitional waters. In the last assessment, 4% (4,442) of waterbodies still had unknown ecological status, while in 23% monitoring did not include in situ water sampling to support ecological status assessment2. For individual (mainly biological) assessment criteria the proportion of waterbodies without observation data is much larger; the full scope of monitoring under the WFD is therefore still far from being realised. At the same time, 60% of surface waters did not achieve ‘good’ status in the second river basin management plan and waterbodies in Europe are considered to be at high risk of having poor water quality based on combined microbial, physical and physicochemical indicators3

GLORIA - A globally representative hyperspectral in situ dataset for optical sensing of water quality

The development of algorithms for remote sensing of water quality (RSWQ) requires a large amount of in situ data to account for the bio-geo-optical diversity of inland and coastal waters. The GLObal Reflectance community dataset for Imaging and optical sensing of Aquatic environments (GLORIA) includes 7,572 curated hyperspectral remote sensing reflectance measurements at 1 nm intervals within the 350 to 900 nm wavelength range. In addition, at least one co-located water quality measurement of chlorophyll a, total suspended solids, absorption by dissolved substances, and Secchi depth, is provided. The data were contributed by researchers affiliated with 59 institutions worldwide and come from 450 different water bodies, making GLORIA the de-facto state of knowledge of in situ coastal and inland aquatic optical diversity. Each measurement is documented with comprehensive methodological details, allowing users to evaluate fitness-for-purpose, and providing a reference for practitioners planning similar measurements. We provide open and free access to this dataset with the goal of enabling scientific and technological advancement towards operational regional and global RSWQ monitoring

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.Peer reviewe

Toiteainete mõju fütoplanktoni koosluse dünaamikale

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Veekogu eutrofeerumine on looduslik protsess, mille kiirus oleneb valgalalt sissekantavate toiteainete hulgast. Üheks eutrofeerumise ilminguks on fütoplanktoni liigne hulk, mis põhjustab hapnikusisalduse ja pH kõikumist, veekogude mudastumist ja stressitingimusi veekogu asukatele. Fütoplankton on toiduahela aluslüliks, mõjutades kogu toiduvõrgustikku. Iga-suvised veeõitsengud on järvedes ja Läänemeres suureks probleemiks, mistõttu nende efektiivseks majandamiseks on vaja eelteadmisi sellest, kuidas toiteainete hulga muutus mõjutab vetikaliike. Mikrovetikad reageerivad toiteainete hulga muutustele suhteliselt kiiresti muutustega nii liigilises koosseisus kui biomassis. Eksperimentidest selgus, et mõlemad uuritud kooslused (Odense fjordis kevadel ja Tvärminnes suvel) reageerisid biomassitõusuga toiteainete liiaga lisamisele. Tvärminnes domineeriva sinivetikakoosluse vastus toiteainete lisamisele oli liigi-spetsiifiline. Anorgaanilise lämmastiku puudus põhjustas küll üldiselt fütoplanktoni madalama biomassi, aga protsentuaalselt suurema lämmastiku-fikseerijate hulga. Fosforipuudus vähendas osade lämmastiku-sidujate (Anabaena lemmermannii ja Nodularia spumigena) konkurentsivõimet, aga sinivetikaõitsengut see ei välistanud soodsate tingimuste olemasolul. Lisaks toiteainetele kujundasid kooslust liikide-vahelise konkurentsi vähenemine ja zooplanktoni sööm (väikse-rakulised vaguvibur- ja neelvetikad). Akineetide e. puhkerakkude moodustamine on üks sinivetikate elutsükli oluline osa. A. lemmermannii akineetide produktsioon oli kõrgem fosforipuuduse korral. Liigse toiteainete lisandumise tõttu oluliselt muutunud fütoplanktoni koosluse näiteks on Verevi järv – algselt mesotroofsest seisundist Planktothrix agardhii domineerimisega hüpertroofseks järveks (80ndail). Praeguses faasis iseloomustab järve suhteliselt suur läbipaistvus ning eutroofsele seisundile vastav vetikakooslus, kuid seisundi paranemine võib olla ajutine hüpolimnionis ja setetes oleva suure toiteainevaru tõttu.Phytoplankton is the base of a food-chain; its biomass and composition influence the whole functioning of a water body. Extra nutrients cause excess phytoplankton biomass, with fluctuations in O2 content and pH, increased sedimentation and stress to other inhabitants. Cyanobacterial blooms in lakes and in the Baltic Sea are an increasing problem, thus for the successive management the knowledge of species reaction to the changes in nutrient loading is indispensable. From experiments was evident that in both studied communities (Odense Fjord in spring and Tvärminne in summer) the mineral nutrient addition led to a rapid increase of phytoplankton biomass. Moderate, even excessive N additions lowered the competitive ability of some filamentous cyanobacteria (Anabaena spp.), but generally failed to prevent cyanobacterial bloom due to Aphanizomenon sp., when other conditions were favourable. Cutting the nitrogen supply resulted in lower phytoplankton total biomass, but in elevated relative amount of nitrogen-fixing cyanobacteria. Nutrient limitation did not explain the whole dynamics of phytoplankton community, for example Aphanizomenon sp. used internal phosphorus reserves and grew well independently of nutrients. Other factors (temperature, zooplankton grazing and reduced competition with other species) were important in shaping the phytoplankton community composition. Production of akinetes is an important part of the life-cycle of Nodulariaceae. Anabaena lemmermannii produced more akinetes in P-limited conditions. Lake Verevi can be used as an example of cultural eutrophication and intensive changes in phytoplankton community due to nutrient pollution – from initially mesotrophic to a hypertrophic lake with monodominating Planktothrix agardhii in eighties. In the present state water transparency has increased, the phytoplankton biomass has decreased, but this improvement may be temporary, since nutrients are still present in the hypolimnion and in the sediments

Recreation center of company UPM-Kymmene Otepää

Käesoleva magistritöö alusel võib teha järgnevad kokkuvõtted ja järeldused: 1. Rekreatiivse tegevuse sihiks on inimese tervise tugevdamine, sh töövõime ja enesetunde parandamine. Tagatiseks on terved eluviisid, mille peamisteks komponentideks on töö ja puhkuse, nii vaimse kui füüsilise töö sobiv vaheldumine. 2. Uurimistöö objektiks on ettevõte UPM-Kymmene Otepää, mis asutati 2000.aastal FSS Plywood AS nime all. 2003 a. aprillis läks UPM-Kymmene Otepää AS 100%-liselt UPM-Kymmene Wood Oy omandusse. 3. Tehasel on kaks tootmisliini, kus ühes toodetakse baasvineeri ja teises eriotstarbelist vineeri. 4. Tootmisettevõttes viidi läbi ankeetküsitlus, millest võttis osa 13 töötajat. Ankeetküsitluses osalenud meestöötajatest hindasid 37,5% puhkeruumi heaks, 62,5% rahuldavaks. Pesemisruumi ehk duširuumi pidasid 37,5% vastanud meestest halvaks ja sama palju hindas seda ruumi rahuldavaks. Riietusruumi hindasid meestöötajad 62,5% rahuldavaks ja 12,5% halvaks ja väga halvaks. 5. Naistöötajad hindasid 60% ulatuses kõiki ruume pigem väga halvaks. Puhkeruumi hinnati 20% heaks ja 20 % rahuldavaks. 40% vastanutest pidas riietusruumi rahuldavaks. Pesemisruumi ja tualettruumi hinnati 20% rahuldavaks ja samas ka halvaks. 6. Fotomeetod põhines uuritavates ruumides tehtud fotodel, sest ankeet- ja mõõtmismeetod ei anna visuaalset ülevaadet ruumide seisukorrale. 7. Naiste riietusruumis jäi silma riietuskappide ustel ja kuivatusrestil kuivavad käterätikud, mis suurendavad õhu suhtelise niiskuse taset. 8. Naiste riietusruumis oli valgusti, mis oli lae küljest lahti tulnud ja rippus juhtmete toel. Elektriohutuse tagamiseks tuleks see korralikult lae külge kinnitada. 9. Naiste duširuumi laes oli näha niiskusest põhjustatud kahjustust ja hallitust. Soovitatavalt tuleks laest eemaldada hallitus ja täiustada ventilatsioonisüsteemi, et liigne niiskus saaks ruumist eemaldatud ja hallitust enam ei tekiks. 10. Meeste riietusruumis olid kappide vahelised käiguteed kitsamad kui naistel. Kitsaste käiguteede tõttu ei olnud kõikide kappide ees istumise võimalus tagatud. 11. Selleks, et töötajad tunneksid end olmeruumides hästi peavad need olema puhtad ja meeldivad, kuid nende ruumide puhul see nii ei ole. 12. Kõige parema mulje fotomeetodil analüüsides jättis puhkeruum. Puhkeruum oli uuritavatest ruumidest kõige heledam ja valgusrikkam. Ruumis oli olemas istumiseks toolid ja lauad ning pikali viskamiseks lamamistool. 13. UPM-Kymmene Otepää AS olmeruumides on tehtud sisekliima füüsikaliste parameetrite mõõtmised. Antud ruumides on mõõdetud järgnevaid parameetreid: õhu temperatuur k (°C) , õhu liikumiskiirus v (m/s), õhu suhteline niiskus W (%), valgustatus E (lx), müratase M (db(A)). 14. Mõõtmistulemused erinesid ruumide lõikes kõige enam valgustatuse osas, sest nii meeste kui naiste riietusruumid koosnevad kahest ruumiosast. Üks osa riietusruumist on valgustatud ainult tehisvalgustusega, sest seal puuduvad aknad, seda nii naiste kui meeste riietusruumis. 15. Puhkeruumi einelaudadel oli valgus loomuliku ja laevalgustuse koosmõjul keskmiselt 565 lx ja standardi kohaselt peaks see olema 200 lx. Müratase naiste ja meeste riietusruumis oli vastavalt 43,6 ja 44,5 dB(A) ja puhkeruumis 49,4 dB(A), mis ei ületa päevast lubatud piiri. 16. Töökeskkonna analüüs põhineb töötajaid kõige enam töökeskkonnas mõjutavatele teguritele. 17. Kõige enam mõjutab töötajaid töökeskkonnas esinev müra. Müratase rohkem kui pooltel töökohtadel ületas lubatava piirnomi. Ettevõttes on müra mõju vähendamiseks töötajatele rakendatud kuulmiskaitsevahendite kasutamine. 18. Lisaks füüsikalistele mõjuritele mõjutavad töötajaid ka füüsiline koormus ja sundasendid. 19. Ilmastikutingimused mõjutavad välitingimustes töökohustusi täitvaid töötajaid. Peamisteks mõjutatavateks on palgimõõtjad, frontaallaaduri operaator ning tõstukijuhid. 20. Rekreatsioonikeskuse eesmärgiks uuritavas ettevõttes on töötajate töövõime taastamine. Rekreatsioonikeskuse kavandamisel on lähtutud uurimistöö meetodite analüüsidest ning töös tehtud soovitustest, mida võimalusel on rakendatud. 21. Rekreatsioonikeskus koosneks kahest osast: rekreatsiooniruumist ja „vaiksest ruumist“. 22. Rekreatsiooniruumis on võimalik puhkeaega veeta nii aktiivselt kui ka lõõgastavalt. 23. Aktiivseks puhkeaja veetmiseks on ruumis piljardilaud, lauatennis, lauajalgpall kui ka malelaud. 24. Lõõgastavateks võimalusteks on töötajatele mõeldud lamamistool pikali heitmiseks, massaažitool ja teleri vaatamise võimalus ning lisaks muusikakeskus ja raamatu lugemise võimalus. 25. „Vaikne ruum“ oleks rekreatsioonikeskuse üheks osaks, mille eesmärgiks on pakkuda töötajatele 10...15 minutilist eemaldumist mürarikkast töökeskkonnast puhkepauside ajal. 26. Ruumi sisustamisel on lähtutud töötajate töö iseärasustest ning puhkeaja võimalikust lõõgastavast veetmisest. 27. Keskuse loomisega tuleks ettevõttel üle vaadata töötajate töö- ja puhkeaeg, et võimaldada neile plaanitava keskuse kasutamist nii tööpäeva keskel kui ka lõpus. 28. Rekreatsioonikeskuse puhul ei ole võimalik ennustada, kuidas töötajad selle vastu võtavad ja kas seda kasutama hakatakse. Seetõttu on ettevõtte investeering suureks riskiks.The company is a buisness unit whose main objectives are production quality, achieving or maintaining the competitiveness, improving profitability, reducing costs, ensuring adequate liquidity and reputation, and objectives conserning the employee well-being. In addition to working conditions, the company is committed to ensure all municipal facilities to employees. The employee’s ability to work changes over time. Also with the decrease of the working ability the probability of exposure of accidents at work increase. Therefore, companies are paying more attention to the rehabilitation of employees. The aim of the reasearch was to examine the comapany’s UPM-Kymmene Otepää production processes and its municipal facilities, that its possible to plan suitable recreation centre according company’s needs. The approach of this reasearch is to create recreation centre to restore the empoyee’s ability to work. Therefore it is necessery to study company’s working environment and minicipal facilities. According these analyses it is possible to plan recreation centre considering the needs of the company. But creating the centre is always a risk that employees are not intrested

Detecting cyanobacterial blooms in large North European lakes using the Maximum Chlorophyll Index

The Maximum Chlorophyll Index (MCI), developed for the MERIS sensor processing scheme, is used to investigate the seasonaldynamics, spatial distribution, and coverage of cyanobacterial blooms over Lake Peipsi (Estonia/Russia) and Lake Võrtsjärv(Estonia). In these optically complex waters, the amounts of suspended matter and dissolved organic matter vary greatly andindependently of the phytoplankton biomass. We demonstrate that MCI is a useful, new tool for detecting and estimating cyanobacterialbiomass (R2 = 0.73), phytoplankton biomass (R2 = 0.70) and chlorophyll a concentration (R2 = 0.64). The MCI-derivedresults are consistent with known patterns of phytoplankton dynamics in these lakes, whose optical properties are in the same range as in many coastalregions of the Baltic Sea

Long-term Changes and Seasonal Development of Phytoplankton in a Strongly Stratified Hypertrophic Lake

Changes in the phytoplankton community of the hypertrophic, sharply stratified Lake Verevi have been studied over eight decades. Due to irregular discharge of urban wastewater, the trophic state of the lake has changed from moderately eutrophic to hypertrophic. We found that the trophic state in summer increased in the 1980s and remained at a hypertrophic level since then. Planktothrix agardhii was recorded first in the 1950s and became the dominant species in the 1980s, forming biomass maxima under the ice and in the metalimnion during the vegetation period.JRC.H.5-Rural, water and ecosystem resource

Comparison of Spectral and Broad-band Models for Computing Photosynthetically Absorbed Radiation in Turbid Waters

A comparison of values of photosynthetically absorbed radiation calculated with spectral and broad-band models was performed. Special attention was paid to turbid lake waters (Secchi depth ranging from 0.3 to 3 m). Ten measurement series of bio-optical characteristics were carried out in June and August 2003 at three Estonian lakes, Peipsi, Võrtsjärv and Harku. Photosynthetically absorbed radiation was calculated from measured quantum irradiance and a radiation model. The results obtained showed that in case of moderately clear waters (Secchi depth about 3 m) it is especially important to use a correct spectral model, as the errors of the broad-band model can be more than 40%–50%. For very turbid waters these errors usually do not exceed 20%. In our measurement results there was a rather remarkable variability of the bio-optical characteristics of the lakes. The relationships between depth-averaged assimilation number and primary production and between depth-integrated primary production and chlorophyll concentration could be described by polynomial functions with intercept = 0.JRC.H.5-Rural, water and ecosystem resource