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”

Slaughter weight rather than sex affects carcass cuts and tissue composition of Bisaro pigs

Carcass cuts and tissue composition were assessed in Bisaro pigs (n=64) from two sexes (31 gilts and 33 entire males) reared until three target slaughter body-weights (BW) means: 17 kg, 32 kg, and 79 kg. Dressing percentage and backfat thickness increased whereas carcass shrinkage decreased with increasing BW. Slaughter weight affected most of the carcass cut proportions, except shoulder and thoracic regions. Bone proportion decreased linearly with increasing slaughter BW, while intermuscular and subcutaneous adipose tissue depots increased concomitantly. Slaughter weight increased the subcutaneous adipose tissue proportion but this impaired intramuscular and intermuscular adipose tissues in the loin primal. The sex of the pigs minimally affected the carcass composition, as only the belly weight and the subcutaneous adipose tissue proportions were greater in gilts than in entire males. Light pigs regardless of sex are recommended to balance the trade-offs between carcass cuts and their non-edible compositional outcomes.Work included in the Portuguese PRODER research Project BISOPORC – Pork extensive production of Bísara breed, in two alternative systems: fattening on concentrate vs chesnut, Project PRODER SI I&DT Medida 4.1 “Cooperação para a Inovação”. The authors are grateful to Laboratory of Carcass and Meat Quality of Agriculture School of Polytechnic Institute of Bragança ‘Cantinho do Alfredo’. The authors are members of the MARCARNE network, funded by CYTED (ref. 116RT0503).info:eu-repo/semantics/publishedVersio

Happe-aluse tasakaalud vähepolaarsetes keskkondades

Käesolva töö eesmärgiks oli olemasolevate happelisuste ja aluselisuste skaalade laiendamine erinevates keskkondades. Lisaks toodi välja ning analüüsiti põhjuseid, miks happliesuse ja aluselisuse järjestus muutub üleminekul ühest keskkonnast teise. Antud töö esimeses osas oli eesmärgiks laiendada olemasolevat happliesuse skaalat heptaanis. Oma olemuselt on heptaan apolaarne (D = 1.92) ja seetõttu lahustuvad polaarsed ning ioonsed ühendid heptaanis väga halvasti. Happelisuste mõõtmise edukuse tagab eelkõige osalevate ainete – nii tiitrimisel kasutatava aluse kui ka uuritavate hapete – õige valik. Töö tulemusena laiendati olemasolevat heptaani happelisuse skaalat ligikaudu 10 pKip ühikuni. Korrelatsioonid heptaani ja teiste keskkondade vahel näitasid, et CH-hapete jaoks on heptaani skaala võrreldes gaasifaasiga 1,2 korda kokku surutum ja NH-hapete jaoks on heptaan parema diferentseeriva võimega kui dimetüülsulfoksiid. Töö teise osa peamiseks eesmärgiks oli laiendada olemasolevat aluselisuste skaalat gaasifaasis, tugevate orgaaniliste hapete osas. Töö käigus ehitati kooskõlaline aluselisuste skaala ulatusega 243.7 kuni 264.6 kcal·mol-1, millest umbes 15 kcal·mol-1 on olemasoleva gaasifaasi orgaaniliste aluste skaala laiendus. Paljudele uuritud alustele arvutati ka teoreetiline gaasifaasi aluselisus DFT B3LYP/6-311+G** tasemel. Eksperimentaalsed ja arvutatud aluselisused leiti olevat heas kooskõlas. Lisaks tehti mitmeid võrdlusi gaasifaasi ning eri solventide aluselisuste vahel. Selgus, et korrelatsioon gaasifaasi ja solvendi aluselisuste vahel paraneb märgatavalt kui võtta arvesse molekuli suurusest tulenevaid muutusi gaasifaasi aluselisustes. Antud töö kolmadas osas uuriti α,ω-diaminoalkaanide, kui perekonna, aluselisusi tetrahüdrofuraanis, atseetonitriilis ja gaasifaasis. Peamiseks eesmärgiks oli võrrelda diaminoalkaanide võimet moodustada vesinik-sidet ja selle mõju osakaalu aluselisustele eri keskkondades. Töö tulemusna mõõdeti atseetonitriilis, tetrahüdrofuraanis ja gaasifaasis vastavalt 16, 14 ja 9 diamiini aluselisused. Lisaks arvutati aluselisused ja tasakaalugeomeetriad DFT B3LYP 6-311+G** tasemel 19 diamiini ja 15 sarnase monoamiini jaoks. Isodesmiliste reaktsioonide meetodiga hinnati lisaks erinevate faktorite (aminogruppide endi aluselisus, molekulisisese vesiniksideme moodustumine, molekuli steeriline pingestatus jne) osakaalu diamiinide aluselisuse kujunemisel. Tulemused näitavad, et gaasifaasi aluseslise määravad molekuli suurus, polariseeritavus, lämmastike küljes olevate alküülrühmade arv ja energeetiline efekt mis on seotud sisemolekulaarse vesiniksideme moodustumisega. Aluselisuste järjestus solventides erineb tugevasti olukorrast gaasifaasist: (1) solvendid suruvad aluselisuse skaalat tugevalt kokku ja (2) samm-sammuline alküülrühmade lisamine aluselisuse tsentrile, mis gaasifaasis tõi kaasa ühtlase aluselisuse suurenemise, on solventides tulemuselt märksa ettearvamatum. Märgatavad erinevused on välja toodavad ka tetrahüdrofuraani ja atseetonitriili vahel. Tugeva vesiniksideme aktseptorina eelistab tetrahüdrofuraan aluseid mille protoneerumistsenter pole varjestatud. Silmatorkav on siin näiteks N-metüleeritud 1,3-propaandiamiinide aluselisuste järjekord, mis on sisuliselt vastupidine võrreldes gaasifaasi aluselisustega. Atseetonitriilis on olukord gaasifaasi ja tetrahüdrofuraaniga võrreldes vahepealne

Detecting climate driven changes in chlorophyll-a using high frequency monitoring: the impact of the 2019 European heatwave in three contrasting aquatic systems

The frequency of heatwave events in Europe is increasing as a result of climate change. This can have implications for the water quality and ecological functioning of aquatic systems. We deployed three spectroradiometer WISPstations at three sites in Europe (Italy, Estonia, and Lithuania/Russia) to measure chlorophyll-a at high frequency. A heatwave in July 2019 occurred with record daily maximum temperatures over 40 °C in parts of Europe. The effects of the resulting storm that ended the heatwave were more discernable than the heatwave itself. Following the storm, chlorophyll-a concentrations increased markedly in two of the lakes and remained high for the duration of the summer while at one site concentrations increased linearly. Heatwaves and subsequent storms appeared to play an important role in structuring the phenology of the primary producers, with wider implications for lake functioning. Chlorophyll-a peaked in early September, after which a wind event dissipated concentrations until calmer conditions returned. Synoptic coordinated high frequency monitoring needs to be advanced in Europe as part of water management policy and to improve knowledge on the implications of climate change. Lakes, as dynamic ecosystems with fast moving species-succession, provide a prism to observe the scale of future change

Plastic debris in freshwater systems worldwide

Plastic debris is widespread in freshwater ecosystems, but a rigorous assessment of its global distribution has been hindered by a lack of comprehensive and comparable data. We performed the first standardized global survey of lakes to assess the quantity and type of plastics (>250μm). We included 38 lakes located in 23 different countries distributed across five continents, spanning different environmental gradients and varying levels of anthropogenic stress. All samples were collected by horizontal trawling of a plankton net and subsequently treated with hydrogen peroxide. We identified 9425 plastic particles, which were classified based on shape, color, and size. Polymer identification was carried out using Raman micro-spectroscopy. Our results showed that the concentration of plastics spanned four orders of magnitude (10-3-101 particles/m3). Fibers (49%) and fragments (41%) were the most frequently detected particles, suggesting a secondary origin of plastic contamination. The most commonly identified polymers were polyester (30%), polypropylene (20%), and polyethylene (16%), which are widely used in short life-cycle products and account for the majority of global plastic production. Further, we found that urban-related attributes of lakes/watersheds influenced the occurrence and type of plastics in lentic systems and larger and deeper lakes with higher retention times are accumulating plastic debris at higher concentrations.info:eu-repo/semantics/publishedVersio

Plastic debris in lakes and reservoirs

Plastic debris is thought to be widespread in freshwater ecosystems globally. However, a lack of comprehensive and comparable data makes rigorous assessment of its distribution challenging. Here we present a standardized cross-national survey that assesses the abundance and type of plastic debris (>250 μm) in freshwater ecosystems. We sample surface waters of 38 lakes and reservoirs, distributed across gradients of geographical position and limnological attributes, with the aim to identify factors associated with an increased observation of plastics. We find plastic debris in all studied lakes and reservoirs, suggesting that these ecosystems play a key role in the plastic-pollution cycle. Our results indicate that two types of lakes are particularly vulnerable to plastic contamination: lakes and reservoirs in densely populated and urbanized areas and large lakes and reservoirs with elevated deposition areas, long water-retention times and high levels of anthropogenic influence. Plastic concentrations vary widely among lakes; in the most polluted, concentrations reach or even exceed those reported in the subtropical oceanic gyres, marine areas collecting large amounts of debris. Our findings highlight the importance of including lakes and reservoirs when addressing plastic pollution, in the context of pollution management and for the continued provision of lake ecosystem services