Combatting cyanobacteria with hydrogen peroxide: a laboratory study on the consequences for phytoplankton community and diversity

Experiments with different phytoplankton densities in lake samples showed that a high biomass increases the rate of hydrogen peroxide (HP) degradation and decreases the effectiveness of HP in the selective suppression of dominant cyanobacteria. However, selective application of HP requires usage of low doses only, accordingly this defines the limits for use in lake mitigation. To acquire insight into the impact of HP on other phytoplankton species, we have followed the succession of three phytoplankton groups in lake samples that were treated with different concentrations of HP using a taxa-specific fluorescence emission test. This fast assay reports relatively well on coarse changes in the phytoplankton community; the measured data and the counts from microscopical analysis of the phytoplankton matched quite well. The test was used to pursue HP application in a Planktothrix agardhii-dominated lake sample and displayed a promising shift in the phytoplankton community in only a few weeks. From a low-diversity community, a change to a status with a significantly higher diversity and increased abundance of eukaryotic phytoplankton species was established. Experiments in which treated samples were re-inoculated with original P. agardhii-rich lake water demonstrated prolonged suppression of cyanobacteria, and displayed a remarkable stability of the newly developed post-HP treatment state of the phytoplankton community

Adaptational problems among overseas students

СТУДЕНТЫ МЕДИЦИНСКИХ УЧЕБНЫХ ЗАВЕДЕНИЙОБРАЗОВАНИЕСТУДЕНТЫ 1-2 КУРСОВ МЕДИНСТИТУТАОБРАЗОВАНИЕ МЕДИЦИНСКОЕМЕДИЦИНСКИЕ УЧЕБНЫЕ ЗАВЕДЕНИЯУЧЕБНЫЕ ЗАВЕДЕНИЯ МЕДИЦИНСКИЕОБУЧЕНИЕПРЕПОДАВАНИЕОДЕЖДАВИТЕБСКИЙ ГОСУДАРСТВЕННЫЙ ОРДЕНА ДРУЖБЫ НАРОДОВ МЕДИЦИНСКИЙ УНИВЕРСИТЕТАНАТОМИЯ ЧЕЛОВЕКА (ДИСЦИПЛИНА)ВЫСШЕЕ ОБРАЗОВАНИЕСАМОСТОЯТЕЛЬНАЯ ПОДГОТОВКАУЧЕБНЫЙ ПРОЦЕССПРОБЛЕМЫ АДАПТАЦИИАДАПТАЦИЯ ИНОСТРАННЫХ СТУДЕНТОВУНИФОРМАМОРФОЛОГИЧЕСКИЕ ДИСЦИПЛИНЫПОДГОТОВКА К ЗАНЯТИЯМЯЗЫКОВАЯ АДАПТАЦИЯЯЗЫКОВОЙ БАРЬЕРИНОСТРАННЫЕ СТУДЕНТ

Adaptational problems among overseas students

СТУДЕНТЫ МЕДИЦИНСКИХ УЧЕБНЫХ ЗАВЕДЕНИЙОБРАЗОВАНИЕСТУДЕНТЫ 1-2 КУРСОВ МЕДИНСТИТУТАОБРАЗОВАНИЕ МЕДИЦИНСКОЕМЕДИЦИНСКИЕ УЧЕБНЫЕ ЗАВЕДЕНИЯУЧЕБНЫЕ ЗАВЕДЕНИЯ МЕДИЦИНСКИЕОБУЧЕНИЕПРЕПОДАВАНИЕОДЕЖДАВИТЕБСКИЙ ГОСУДАРСТВЕННЫЙ ОРДЕНА ДРУЖБЫ НАРОДОВ МЕДИЦИНСКИЙ УНИВЕРСИТЕТАНАТОМИЯ ЧЕЛОВЕКА (ДИСЦИПЛИНА)ВЫСШЕЕ ОБРАЗОВАНИЕСАМОСТОЯТЕЛЬНАЯ ПОДГОТОВКАУЧЕБНЫЙ ПРОЦЕССПРОБЛЕМЫ АДАПТАЦИИАДАПТАЦИЯ ИНОСТРАННЫХ СТУДЕНТОВУНИФОРМАМОРФОЛОГИЧЕСКИЕ ДИСЦИПЛИНЫПОДГОТОВКА К ЗАНЯТИЯМЯЗЫКОВАЯ АДАПТАЦИЯЯЗЫКОВОЙ БАРЬЕРИНОСТРАННЫЕ СТУДЕНТ

Loadings of dissolved organic matter and nutrients from the Neva River into the Gulf of Finland - Biogeochemical composition and spatial distribution within the salinity gradient

We studied the loadings of dissolved organic matter (DOM) and nutrients from the Neva River into the Eastern Gulf of Finland, as well as their distribution within the salinity gradient. Concentrations of dissolved organic carbon (DOC) ranged from 390 to 840 mu M, and were related to absorption of colored DOM (CDOM) at 350 nm, a(CDOM)(350), ranging from 2.70 to 17.8 m(-1). With increasing salinity both DOC and a(CDOM) decreased, whereas the slope of a(CDOM) spectra, S-CDOM(300-700), ranging from 14.3 to 21.2 mu m(-1), increased with salinity. Deviations of these properties from conservative mixing models were occasionally observed within the salinity range of approximately 1-4, corresponding to the region between 27 and 29 degrees E. These patterns are suggested to mostly reflect seasonal changes in properties of river end-member and hydrodynamics of the estuary, rather than non-conservative processes. On the other hand, observed nonlinear relationships observed between a(CDOM)*(350) and S-CDOM(275-295) emphasized the importance of photochemistry among various transformation processes of DOM. Dissolved inorganic nitrogen was effectively transformed in the estuary into particulate organic nitrogen (PON) and dissolved organic nitrogen (DON), of which DON was mostly exported from the estuary, enhancing productivity in nitrogen limited parts of the Gulf of Finland. DON concentrations ranged from 12.4 to 23.5 mu M and its estuarine dynamics were clearly uncoupled from DOC. In contrast to DOC, estuarine DON dynamics suggest that its production exceeds losses in the estuary. Total nitrogen (TN) and phosphorus (TP) loadings from the Neva River and St. Petersburg were estimated as 73.5 Gg N yr(-1) and 4.2 Gg P yr(-1), respectively. Approximately 59% of TN and 53% of TP loads were in organic forms. DOC and DON loadings were estimated as 741.4 Gg C yr(-1) and 19.0 Gg N yr(-1), respectively. Our estimate for DOC loading was evaluated against a previously published carbon budget of the Baltic Sea. According to the updated model, the Baltic Sea could be identified as a weak source of carbon into the atmosphere. (C) 2016 The Authors. Published by Elsevier B.V.Peer reviewe

Branched Poly(ethylene imine)s as Anti‐algal and Anti‐cyanobacterial Agents with Selective Flocculation Behavior to Cyanobacteria over Algae

Poly(ethylene imine)s (PEIs) have been widely studied for biomedical applications, including antimicrobial agents against potential human pathogens. The interactions of branched PEIs (B‐PEIs) with environmentally relevant microorganisms whose uncontrolled growth in natural or engineered environments causes health, economic, and technical issues in many sectors of water management are studied. B‐PEIs are shown to be potent antimicrobials effective in controlling the growth of environmentally relevant algae and cyanobacteria with dual‐functionality and selectivity. Not only did they effectively inhibit growth of both algae and cyanobacteria, mostly without causing cell death (static activity), but they also selectively flocculated cyanobacteria over algae. Thus, unmodified B‐PEIs provide a cost‐effective and chemically facile framework for the further development of effective and selective antimicrobial agents useful for control of growth and separation of algae and cyanobacteria in natural or engineered environments.Poly(ethylene imine)s (B‐PEIs) are shown as effective antimicrobial agents against environmentally relevant microorganisms (algae CR – Chlamydomonas reinhardtii, cyanobacterium SE – Synechococcus elongatus). B‐PEIs have dual‐functionalities and can 1) inhibit growth of both algae and cyanobacteria and 2) selectively flocculate cyanobacteria over algae. These molecules provide a cost‐effective and chemically facile framework for the further development of selective anti‐algal and anti‐cyanobacterial agents.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146449/1/mabi201800187_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146449/2/mabi201800187.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146449/3/mabi201800187-sup-0001-SupMat.pd

Diatom responses to 20th century climate warming in lakes from the northern Urals, Russia.

Changes in diatom assemblages and spheroidal carbonaceous particle (SCP) profiles during the last 200 years in 210Pb-dated sediment cores from five remote arctic and sub-arctic lakes in the northern Urals were analysed. The study area covers a large territory from arctic tundra in the north to boreal forest on the western slopes of the Ural mountains in the south. pH was reconstructed using a diatom-based model. The degrees of compositional turn-over and rates-of-change were estimated numerically. The 20th century diatom floristic shifts, the rise in diatom accumulation rates and the rates of diatom compositional change in the northern Ural lakes correlate well with June temperature in the region and with the overall circum-arctic temperature increase from the 1970s. The main driving force behind diatom compositional shifts in the study lakes are the changes in the duration of ice-free season, timing of water turn-over and stratification periods and habitat availability. Changes in spheroidal carbonaceous particles show no pronounced effect on diatom assemblages. Pollution is restricted to regional sources originating mainly from the Vorkuta coal industry. Changes in diatom plankton are more pronounced than changes in diatom benthos. There is no clear north–south gradient in degree of compositional changes, with greatest changes occurring in Lake Vankavad situated in northern boreal forest. The degree of the 20th century diatom changes in Lake Vankavad is greater than in most circum-arctic and sub-arctic lakes from northern Europe and Canada