Treshold-controlled three-stage hydraulic behaviour of a mantled shallow carbonate aquifer (Tuhala karst area, North Estonia)

As karst aquifers are often characterised by non-linear behaviour, ascertaining the turning points in their hydraulic regime may provide essential information on the functioning of the aquifer. These characteristics also apply to the Silurian-Ordovician aquifer system, composed of diverse carbonate rocks, in Estonia. The aquifer system is an important source of drinking water in northern Estonia. It also comprises the Nabala- Rakvere aquifer, a locally important groundwater resource that underlies the Tuhala karst area famous for an intermittently overflowing karst spring known as the Witch's Well. The water rich in humic substances of the Tuhala River recharges the Tuhala karst system, which is drained by two spring groups. In order to develop measures for the sustainable management of the aquifer in the future, the aim of this study was to enhance understanding of the hydraulic behaviour and hydrodynamic properties of the Tuhala karst system. From October 2014 to December 2016 an extensive field campaign was carried out comprising the observation of 22 surface- and groundwater monitoring points for water level and physico-chemical parameters and the performance of four quantitative tracer tests. The data obtained were evaluated in accordance with the input– output water level relation curves and a conceptual model of the system was set up. The results show that a strong hydraulic link exists, primarily through well-developed conduits between the recharge and discharge area of the karst system. Depending on the hydrological conditions, groundwater flow direc tions vary and maximum linear flow velocities range between ~225 and 800 m/h. A threshold-controlled throughput capacity and interaction with the adjacent aquifer cause imbalances between the input and output discharges of the karst system. Tracer tests coupled with surface and groundwater level relation curve analysis allowed the specification of flow threshold conditions for the Witch's Well spring group and the overflow threshold for the Witch's Well, among other key hydrological events. The hydraulic regime of the karst system was divided into three stages, each with differing threshold controls and hydrodynamic characteristics.Key words: karst system, shallow carbonate aquifer, monitoring, tracer test, water level relation curve, threshold, overflow. Določanje mejnih vrednosti tristopenjskega hidravljičnega obnašanja pokritega plitvega karbonatnega vodonosnika (Tuhalski kras, severna Estonija)Kraški vodonosniki se pogosto obnašajo nelinearno, zato lahko z ugotavljanjem mejnih vrednosti v hidravličnem režimu zagotovimo bistvene informacije o delovanju vodonosnika. To velja tudi za silurijsko-ordovicijski vodonosni sistem v Estoniji, ki ga sestavljajo različne karbonatne kamnine in je pomemben vir pitne vode na severu države. Vključuje tudi vodonosnik Nabala- Rakvere, ki je lokalno pomemben vodni vir. Na tem območju se nahaja Tuhalski kras, ki je znan po občasno bruhajočem kraškem izviru Witch's Well (Čarovničin vodnjak). Tuhalski vodonosnik napaja reka Tuhala, bogata z huminskimi snovmi, prazni pa se skozi dve skupini izvirov. Da bi v prihodnje razvili ukrepe za trajnostno upravljanje vodonosnika, je bil namen te raziskave izboljšati razumevanje hidravličnega obnašanja in hidrodinamičnih lastnosti kraškega sistema. Od oktobra 2014 do decembra 2016 smo opravili obsežno terensko delo, ki je obsegalo spremljanje vodostajev in fizikalno-kemijskih parametrov v 23 površinskih in podzemnih točkah ter izvedbo štirih kvantitativnih sledilnih poskusov. Pridobljene podatke smo ovrednotili na podlagi krivulje odvisnosti vhodnih in izhodnih vodnih nivojev. Vzpostavili smo konceptualni model sistema. Rezultati kažejo na obstoj močne hidravlične povezave predvsem z dobro razvitimi kanali med območji napajanja in praznjenja kraškega sistema. Odvisno od hidroloških razmer se spreminjajo smeri in hitrosti toka podzemne vode, ki znašajo od ~225 do 800 m/h. Kapaciteta prepustnosti, ki jo uravnavajo določene mejne vrednosti, in posledične in terakcije s sosednjimi vodonosniki povzročajo neravnovesja med vhodnimi in izhodnimi pretočnimi vrednostmi kraškega sistema. Združevanje rezultatov sledilnih poskusov z analizo krivulje odvisnosti površinskih in podzemnih vodostajev nam je omogočilo, da smo določili mejne pretočne vrednosti izvira Witch's Well in druge ključne hidrološke dogodke. Hidravlični režim kraškega sistema smo razdelili na tri faze, od katerih ima vsaka določene mejne vrednosti in hidrodinamične lastnosti. Ključne besede: kraški sistem, plitvi karbonatni vodonosnik, monitoring, sledilni poskus, krivulja odvisnosti vodnih nivojev, prag, preliv.

Improved C5D Electronic Realization of Conductivity Detector for Capillary Electrophoresis

The axial C4D (Capacitively Coupled Contactless Conductivity Detection) measurement electronics for capillary electrophoresis is considered and a new improved C5D compensated detection concept is proposed and tested. Using the idle compensation channel with inversed signal and immediate analogue summation of the active and idle channel currents yields effective suppression of the influence of the parasitic stray capacitance. Preliminary experiments have confirmed at least three-fold improvements of measurement resolution. Realisation of electronics allows flexible tuning of frequency from 0.2 MHz to 2 MHz. The relatively high voltage supply of 15 V for the AC measurement units together with 24- bit accurate analogue-to-digital converter yields additional improvement for the sensitivity

Status of Biodiversity in the Baltic Sea

The brackish Baltic Sea hosts species of various origins and environmental tolerances. These immigrated to the sea 10,000 to 15,000 years ago or have been introduced to the area over the relatively recent history of the system. The Baltic Sea has only one known endemic species. While information on some abiotic parameters extends back as long as five centuries and first quantitative snapshot data on biota (on exploited fish populations) originate generally from the same time, international coordination of research began in the early twentieth century. Continuous, annual Baltic Sea-wide long-term datasets on several organism groups (plankton, benthos, fish) are generally available since the mid-1950s. Based on a variety of available data sources (published papers, reports, grey literature, unpublished data), the Baltic Sea, incl. Kattegat, hosts altogether at least 6,065 species, including at least 1,700 phytoplankton, 442 phytobenthos, at least 1,199 zooplankton, at least 569 meiozoobenthos, 1,476 macrozoobenthos, at least 380 vertebrate parasites, about 200 fish, 3 seal, and 83 bird species. In general, but not in all organism groups, high sub-regional total species richness is associated with elevated salinity. Although in comparison with fully marine areas the Baltic Sea supports fewer species, several facets of the system's diversity remain underexplored to this day, such as micro-organisms, foraminiferans, meiobenthos and parasites. In the future, climate change and its interactions with multiple anthropogenic forcings are likely to have major impacts on the Baltic biodiversity

Eesti rannikuvete fütoplanktoni muutlikkus, trendid ja seosed keskkonnateguritega

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Muutused fütoplanktoni kui mere ökosüsteemi ühe aluskomponendi koosseisus kutsuvad esile nii struktuurseid kui funktsionaalseid nihkeid toiduahela järgmistes lülides. Töös on analüüsitud Eesti rannikumere erinevatest osadest kogutud seireandmeid 1990-ndate algusest kuni praeguseni. Saadud tulemused fikseerivad fütoplanktoni sesoonse dünaamika põhijooned. Fütoplanktoni liigilise koosseisu aastatevahelist ja sesoonisisest varieeruvust seletatavad ühelt poolt ilmastikutingimusted ning teiselt poolt vee toitainetesisaldus. Temperatuur ja soolsus on peamised tegurid, mis kujundavad Läänemere, sealhulgas Soome lahe fütoplanktoni koosluste struktuuri ja levikut. Lühikesel ajaskaalal on looduslike ja inimtekkeliste protsesside osakaalu määramine fütoplanktoni dünaamikas keeruline, sest püsivama iseloomuga muutused leiavad aset järk-järgult ning isegi mõõdukas toitainetesisalduse kasv peegeldub liigilises koosseisus vähemärgatavalt. Fütoplanktoni ajalis-ruumiline varieeruvus tingib, et sesoonseid muutusi tuleb jälgida võimalikult väikese ajasammuga, ent samas vaatluste ja analüüsikulusid mõistlikul tasemel hoides. Traditsiooniliste meetodite kõrval saab seiret tõhustada kommertsalustele paigaldatud järelvalveta mõõtmis- ja proovikogumissüsteemide abil. Teadmised fütoplanktoni koosluste suktsessiooni ja üksikute liikide ajalis-ruumilist dünaamika kohta võimaldavad anda soovitusi seiresageduse optimeerimiseks, arvestades vetikaõitsengute esinemise ajalisi mustreid ja õitsenguvaheliste perioodide suuremat stabiilsust koosluse struktuuris. Pakutakse välja potentsiaalsed uued keskkonnaseisundi indikaatorid Läänemere põhjaosa jaoks.Changes in phytoplankton composition may reflect structural and functional ecosystem shifts. In this thesis, the general patterns of seasonal dynamics in four areas of Estonian operational phytoplankton monitoring have been demonstrated. All data are linked to spatial distributions of abiotic parameters and the results are discussed in relation to present and future environmental challenges to the Baltic Sea. Temperature and salinity are the main factors shaping the phytoplankton communities in the Gulf of Finland. Most of the statistically significant changes over the study period (1993–2010) have been related to increases in the mean seasonal or monthly biomass values at different taxo¬nomic levels. Measuring seasonal changes and inter-annual variability requires extensive sampling efforts. The optimal sampling frequency for the northern parts of the Baltic Sea has been discussed and alternative methods of phytoplankton monitoring introduced. Although phytoplankton biomass and species composition are influenced by different mechanisms, the impact of climate change may be overwhelming in the future and induce changes at higher trophic levels. Therefore it is important to maintain long-term biological monitoring programs to assess the biological response to both relatively slow processes and short-term events in water environment. Phytoplankton is also determined as one of the biological quality elements for the classification of the ecological status of surface waters. Based on high-frequency observations, some potential eutrophication indicator species are proposed for the summer period

Treshold-controlled three-stage hydraulic behaviour of a mantled shallow carbonate aquifer (Tuhala karst area, North Estonia)

As karst aquifers are often characterised by non-linear behaviour, ascertaining the turning points in their hydraulic regime may provide essential information on the functioning of the aquifer. These characteristics also apply to the Silurian-Ordovician aquifer system, composed of diverse carbonate rocks, in Estonia. The aquifer system is an important source of drinking water in northern Estonia. It also comprises the Nabala- Rakvere aquifer, a locally important groundwater resource that underlies the Tuhala karst area famous for an intermittently overflowing karst spring known as the Witch's Well. The water rich in humic substances of the Tuhala River recharges the Tuhala karst system, which is drained by two spring groups. In order to develop measures for the sustainable management of the aquifer in the future, the aim of this study was to enhance understanding of the hydraulic behaviour and hydrodynamic properties of the Tuhala karst system. From October 2014 to December 2016 an extensive field campaign was carried out comprising the observation of 22 surface- and groundwater monitoring points for water level and physico-chemical parameters and the performance of four quantitative tracer tests. The data obtained were evaluated in accordance with the input� output water level relation curves and a conceptual model of the system was set up. The results show that a strong hydraulic link exists, primarily through well-developed conduits between the recharge and discharge area of the karst system. Depending on the hydrological conditions, groundwater flow direc tions vary and maximum linear flow velocities range between \~225 and 800 m/h. A threshold-controlled throughput capacity and interaction with the adjacent aquifer cause imbalances between the input and output discharges of the karst system. Tracer tests coupled with surface and groundwater level relation curve analysis allowed the specification of flow threshold conditions for the Witch's Well spring group and the overflow threshold for the Witch's Well, among other key hydrological events. The hydraulic regime of the karst system was divided into three stages, each with differing threshold controls and hydrodynamic characteristics. Key words: karst system, shallow carbonate aquifer, monitoring, tracer test, water level relation curve, threshold, overflow.  Dolo\vanje mejnih vrednosti tristopenjskega hidravlji\vnega obna\vanja pokritega plitvega karbonatnega vodonosnika (Tuhalski kras, severna Estonija) Kra\vki vodonosniki se pogosto obna\vajo nelinearno, zato lahko z ugotavljanjem mejnih vrednosti v hidravli\vnem re\vimu zagotovimo bistvene informacije o delovanju vodonosnika. To velja tudi za silurijsko-ordovicijski vodonosni sistem v Estoniji, ki ga sestavljajo razli\vne karbonatne kamnine in je pomemben vir pitne vode na severu dr\vave. Vklju\vuje tudi vodonosnik Nabala- Rakvere, ki je lokalno pomemben vodni vir. Na tem obmo\vju se nahaja Tuhalski kras, ki je znan po ob\vasno bruhajo\vem kra\vkem izviru Witch's Well (\varovni\vin vodnjak). Tuhalski vodonosnik napaja reka Tuhala, bogata z huminskimi snovmi, prazni pa se skozi dve skupini izvirov. Da bi v prihodnje razvili ukrepe za trajnostno upravljanje vodonosnika, je bil namen te raziskave izbolj\vati razumevanje hidravli\vnega obna\vanja in hidrodinami\vnih lastnosti kra\vkega sistema. Od oktobra 2014 do decembra 2016 smo opravili obse\vno terensko delo, ki je obsegalo spremljanje vodostajev in fizikalno-kemijskih parametrov v 23 povr\vinskih in podzemnih to\vkah ter izvedbo \vtirih kvantitativnih sledilnih poskusov. Pridobljene podatke smo ovrednotili na podlagi krivulje odvisnosti vhodnih in izhodnih vodnih nivojev. Vzpostavili smo konceptualni model sistema. Rezultati ka\vejo na obstoj mo\vne hidravli\vne povezave predvsem z dobro razvitimi kanali med obmo\vji napajanja in praznjenja kra\vkega sistema. Odvisno od hidrolo\vkih razmer se spreminjajo smeri in hitrosti toka podzemne vode, ki zna\vajo od \~225 do 800 m/h. Kapaciteta prepustnosti, ki jo uravnavajo dolo\vene mejne vrednosti, in posledi\vne in terakcije s sosednjimi vodonosniki povzro\vajo neravnovesja med vhodnimi in izhodnimi preto\vnimi vrednostmi kra\vkega sistema. Zdru\vevanje rezultatov sledilnih poskusov z analizo krivulje odvisnosti povr\vinskih in podzemnih vodostajev nam je omogo\vilo, da smo dolo\vili mejne preto\vne vrednosti izvira Witch's Well in druge klju\vne hidrolo\vke dogodke. Hidravli\vni re\vim kra\vkega sistema smo razdelili na tri faze, od katerih ima vsaka dolo\vene mejne vrednosti in hidrodinami\vne lastnosti. Klju\vne besede: kra\vki sistem, plitvi karbonatni vodonosnik, monitoring, sledilni poskus, krivulja odvisnosti vodnih nivojev, prag, preliv

Changes in phytoplankton communities along a north-south gradient in the Baltic Sea between 1990 and 2008

Evaluation of changes in Baltic Sea phytoplankton communities has been hampered by a lack of quantitative long-term data. We investigated changes in biomass of summer (June–September) phytoplankton over the last two decades (1990–2008) along a north–south gradient in the Baltic Sea. The areas were characterized by different temperature, salinity and nutrient conditions. Thirty taxonomic groups were selected for the statistical analysis. Increases in total phytoplankton, particularly cyanobacterial, biomass were observed in the Gulfs of Bothnia and Finland. In these two areas over the study period cyanobacteria also became abundant earlier in the season, and in the Curonian Lagoon Planktothrix agardhii replaced Aphanizomenon flos-aquae as the most abundant cyanobacterium. In general, water temperature was the most influential factor affecting the summer phytoplankton communities. Our data suggest that temperature increases resulting from climate change are likely to cause basin-specific changes in the phytoplankton communities, which in turn may affect overall ecosystem functioning in the Baltic Sea

Deriving Nutrient Concentrations from Sentinel-3 OLCI Data in North-Eastern Baltic Sea

Nutrients are important elements in marine ecosystems and water quality, and have a major role in the eutrophication of water bodies. Monitoring nutrient loads is especially important for the Baltic Sea, which is especially sensitive to the eutrophication. Using optical remote sensing data in mapping total nitrogen (TN) and total phosphorus (TP) is challenging because these substances do not have a direct influence on the water optics that remote sensing sensors can detect. On the other hand, it would be very rewarding. In this study, more than 25,000 Sentinel-3 Ocean and Land Colour Instrument (OLCI) data algorithms were tested in order to detect the TN and TP concentrations in the Estonian marine waters between 2016–2021. The TN estimations were well derived for Estonian marine waters (R2 = 0.73, RMSE = 4.87 µmolN L−1, MAPE = 14%, n = 708), while the TP estimations were weaker (R2 = 0.38, RMSE = 0.23 µmolP L−1, MAPE = 24%, n = 730). The Estonian marine waters were divided into six geographic regions in order to study the effect of regional water quality on the TN and TP retrievals. The nutrient concentrations were derived in every region when spring and summer periods were treated separately. In this study, the detection of both nutrients was more successful in more closed areas with P deficiency, while in open sea areas it was more challenging. This study shows that it is possible to estimate nutrients, especially TN, from remote sensing data. Consequently, remote sensing could provide a reliable support to the conventional monitoring by covering large marine areas with high temporal and spatial resolution data

<i>Pseudomonas putida</i> Responds to the Toxin GraT by Inducing Ribosome Biogenesis Factors and Repressing TCA Cycle Enzymes

The potentially self-poisonous toxin-antitoxin modules are widespread in bacterial chromosomes, but despite extensive studies, their biological importance remains poorly understood. Here, we used whole-cell proteomics to study the cellular effects of the Pseudomonas putida toxin GraT that is known to inhibit growth and ribosome maturation in a cold-dependent manner when the graA antitoxin gene is deleted from the genome. Proteomic analysis of P. putida wild-type and &#916;graA strains at 30 &#176;C and 25 &#176;C, where the growth is differently affected by GraT, revealed two major responses to GraT at both temperatures. First, ribosome biogenesis factors, including the RNA helicase DeaD and RNase III, are upregulated in &#916;graA. This likely serves to alleviate the ribosome biogenesis defect of the &#916;graA strain. Secondly, proteome data indicated that GraT induces downregulation of central carbon metabolism, as suggested by the decreased levels of TCA cycle enzymes isocitrate dehydrogenase Idh, &#945;-ketoglutarate dehydrogenase subunit SucA, and succinate-CoA ligase subunit SucD. Metabolomic analysis revealed remarkable GraT-dependent accumulation of oxaloacetate at 25 &#176;C and a reduced amount of malate, another TCA intermediate. The accumulation of oxaloacetate is likely due to decreased flux through the TCA cycle but also indicates inhibition of anabolic pathways in GraT-affected bacteria. Thus, proteomic and metabolomic analysis of the &#916;graA strain revealed that GraT-mediated stress triggers several responses that reprogram the cell physiology to alleviate the GraT-caused damage

MARICAL field inter-calibration exercise : Report of the field inter-calibration on sampling and analytical procedures for Estonian, Finnish and Swedish institutes carrying out HELCOM monitoring

Estonian, Finnish and Swedish institutes carrying out national HELCOM Baltic Sea monitoring programmes participated in a field inter-calibration for parameters describing eutrophication. The main outcome was that this kind of comparisons are made all too seldom, and hence, it is suggested that the HELCOM parties could include this kind of field inter-calibrations, either between the neighbouring countries or as a basin-wide project, in their annual monitoring programme