0000000000010909
AUTHOR
Maija Balode
PARTNERSHIP BETWEEN TEACHER AND SECONDARY SCHOOL STUDENT THROUGH LEARNING MATHEMATICS
This article examines secondary school student and teachers cooperation through learning mathematics. The aim of the study is to find out whether the teacher and student cooperation is a partnership. The partnership is viewed as a cooperation where involved work toward mutual goals. Secondary school student - teacher partnership is possible if the teacher trusts students and together with them chooses the learning objectives, the teaching aids and methods of learning. Students take responsibility for their choices and they are motivated to accomplish them if there is possibility to make a choice. The article deals with teachers' views on teaching and students' opinions about what helps and …
Influence of dissolved organic matter from terrestrial origin on the changes of dinoflagellate species composition in the Gulf of Riga, Baltic Sea
A mesocosm experiment was used to investigate the effect of terrestrial-origin dissolved organic matter (DOM) on the development of dinoflagellates in natural summer phytoplankton from the Gulf of Riga. Seawater was collected in the central part of the Gulf of Riga and at the entrance of the Gulf in June 1999. DOM was extracted from Parnu River water by use of tangential ultrafiltration. Experimental series were enriched with DOM, DOM in combination with nitrate and phosphate, and only with inorganic nutrients. Enrichments were added in ranges of their natural concentrations. Dinophysis acuminata, Protoperidinium brevipes and Gymnodinium spp. were dominant species in the initial dinoflagell…
Проект науково-технічної програми Міністерства освіти і науки Латвійської Республіки та Міністерства освіти і науки України
Izdevumā atspoguļota starptautiskā projektā «Migranti sabiedrībā: izaicinājumi izglītībā» veiktā pētījuma gaita un rezultāti. Projekts tapis Latvijas Republikas Izglītības un zinātnes ministrijas un Ukrainas Izglītības un zinātnes ministrijas Zinātnes Tehnoloģiju programmas ietvaros. Tā partneri ir Latvijas Universitāte un Ukrainas Nacionālā Dragomanova pedagoģiskā universitāte. Projekta ilgums - 2 gadi.
Sediment quality assessment using Gmelinoides fasciatus and Monoporeia affinis (Amphipoda, Gammaridea) in the northeastern Baltic Sea
Crustaceans in the order Amphipoda are sensitive organisms for the assessment of sediment quality. In this work we performed 10-day toxicity tests on muddy sediments collected from a total of 29 sites in the Gulf of Finland, the Gulf of Riga and the Gulf of Bothnia (northeastern Baltic Sea) using Baltic Sea species such as the native amphipod Monoporeia affinis (Bousfield, 1989) and the invasive amphipod Gmelinoides fasciatus (Stebbing, 1899), and also compared these results with those of bioassays carried out using the standard test species, laboratory-cultivated amphipod Hyalella azteca (Saussure, 1858). The sediment samples (three cm of the upper layer) were collected by a GEMAX Dual Cor…
Spatial distribution of phytoplankton in the Gulf of Riga during spring and summer stages
Distribution patterns of chlorophyll a, phytoplankton species and biomass were studied in the Gulf of Riga, one of the most eutrophicated areas of the Baltic Sea. Quasi-synoptic measurements were carried out during four seasonal stages (spring bloom 1995, early-summer stage 1994, cyanobacterial bloom 1994, and late summer stage 1993). For each stage, common factor analysis was used to simplify the highly correlated patterns of nutrients, salinity, temperature and the depth of mixed layer. Obtained latent variables were used to explain spatial distribution of phytoplankton. Generally, the distribution of phytoplankton variables followed closely the patterns of nutrient rich fresh water. Duri…
Bioaccumulation of hepatotoxins : A considerable risk in the Latvian environment
Abstract The Gulf of Riga, river Daugava and several interconnected lakes around the City of Riga, Latvia, form a dynamic brackish-freshwater system favouring occurrence of toxic cyanobacteria. We examined bioaccumulation of microcystins and nodularin-R in aquatic organisms in Latvian lakes, the Gulf of Riga and west coast of open Baltic Sea in 2002–2007. The freshwater unionids accumulated toxins efficiently, followed by snails. In contrast, Dreissena polymorpha and most lake fishes (except roach) accumulated much less hepatotoxins. Significant nodularin-R concentrations were detected also in marine clams and flounders. No transfer of nodularin-R and microcystins between lake and brackish …
Sediment quality assessment using survival and embryo malformation tests in amphipod crustaceans: The Gulf of Riga, Baltic Sea AS case study
Abstract The aim of this study was to assess the toxicity of bottom sediment and to estimate the potential effects of contaminated sediment on health of benthic organisms in the Gulf of Riga (eastern Baltic Sea). Two endpoints were used: survival rate (acute toxicity test) of five crustacean amphipod species and frequency of embryo malformation (samples were collected from the field) in the two species. Toxic resistance of living animals to sediment quality was measured as survival rate (%) at 25 study sites from 2010–2012. Significant differences in the toxic resistance between species were found: 80–100% for Monoporeia affinis, 70–95% for Corophium volutator, 38–88% for Pontogammarus robu…
The use of spectral fluorescence methods to detect changes in the phytoplankton community
In vivo fluorescence methods are efficient tools for studying the seasonal and spatial dynamics of phytoplankton. Traditionally the measurements are made using single excitation-emission wavelength combination. During a cruise in the Gulf of Riga (Baltic Sea) we supplemented this technique by measuring the spectral fluorescence signal (SFS) and fixed wavelength fluorescence intensities at the excitation maxima of main accessory pigments. These methods allowed the rapid collection of quantitative fluorescence data and chemotaxonomic diagnostics of the phytoplankton community. The chlorophyll a-specific fluorescence intensities (R) and the spectral fluorescence fingerprints were analysed toge…
Effect ofMicrocystis aeruginosa andNodularia spumigena on survival ofEurytemora affinis and the embryonic and larval development of the Baltic herringClupea harengus membras
Laboratory experiments were carried out to investigate the effect of two strains of Microcystis aeruginosa and a strain of Nodularia spumigena on the survival of Eurytemora affinis (Copepoda) and on the embryonic and larval development of the Baltic spring-spawning herring Clupea harengus membras. The trials were made in water taken from Parnu Bay, at a salinity of 3.7–5.1 psu, a constant temperature (15°C ± 1°C in trials with Eurytemora and herring embryos; 18°C ± 2°C with herring larvae), and an oxygen concentration of 8.8–10.4 ppm. The strains tested had a negative impact on the survival of Eurytemora, as well as on the embryonic development and hatching regime of the Baltic herring. In …
Stimulation of nitrogen-fixing cyanobacteria in a Baltic Sea plankton community by land-derived organic matter or iron addition
In the Baltic Sea, floating blooms of nitrogen-fixing cyanobacteria occur yearly during late summer. These blooms can sometimes be limited by iron. Due to extensive foresting around the Baltic Sea, iron is entering the Baltic Sea partly bound to dissolved organic material (DOM) via rivers. An experiment was performed in 300 l laboratory mesocosms to test the hypothesis that riverine high- molecular weight dissolved organic matter (HMWDOM), extracted by tangential flow filtration >1000 Da, stimulates the biomass of nitrogen-fixing cyanobacteria, by increasing the availability of iron. The addition of iron/EDTA and of DOM resulted in 5 to 10 times higher biomass of nitrogen- fixing cyanobacte…
Plankton community composition in relation to availability and uptake of oxidized and reduced nitrogen
Centre de Recherche en Ecologie Marine et Aquaculture de L'Houmeau (CNRS-IFREMER), BP 5, 17137 L'Houmeau, France ABSTRACT: Trends in nitrogen utilization, determined with 15 N-labeled substrates, were related to blooms of distinct phytoplankton groups in the Gulf of Riga, Baltic Sea, during May, June and July 1999. The dominant phytoplankton groups included diatoms, cryptophytes, dinoflagellates, and fila- mentous cyanobacteria. As the water column became progressively more stratified over the growing season, diatoms comprised a smaller proportion of the total phytoplankton assemblage and almost disappeared by late summer. Their disappearance correlated with undetectable surface-water nitra…
Seasonal dynamics of biomarkers in infaunal clam Macoma balthica from the Gulf of Riga (Baltic Sea)
Abstract Biomarkers are often regarded as “early warning” signals of environmental pollution; however seasonal changes are mentioned as one of the most important factor that influences the activity of biomarkers. The aim of our study was to assess the importance of seasonal variation of selected contaminant biomarkers in Macoma balthica to provide background information for further environmental surveys in the Gulf of Riga. Seasonal variation of biomarkers (acetylcholinesterase (AChE), catalase (CAT), glutathione reductase (GR) and glutathione- S -transferase (GST)) was measured in infaunal clam M . balthica from the southern part of the Gulf of Riga. The majority of biomarkers (GST, CAT an…
The role of inorganic and organic nutrients on the development of phytoplankton along a transect from the Daugava River mouth to the Open Baltic, in spring and summer 1999
Abstract The importance of dissolved silicate (DSi), dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON), phosphate and dissolved organic phosphorus (DOP) on algal growth is analysed for the Gulf of Riga and the adjacent open Baltic Sea. The results of three cruises (May, June, and July, 1999) along a transect across the Gulf of Riga from the entrance to the Daugava River to the open Baltic are presented. Nutrient-limitation was identified on the basis of available nutrient concentrations and stoichiometric analysis. In spring, phosphate appeared to be the algal-growth-potential-limiting nutrient at the entrance of the Daugava River, DSi in the central Gulf, and DIN at the …
Immigrants in Society
This article deals with the problems which are arising in the process of adaptation of immigrants to educational spaces in Ukraine and Latvia upon their arrival in the country of settlement. Among these problems are the differences in educational systems of the output and input countries, difficulties in mastering languages of a learning process in the countries, overcoming misunderstanding in intercultural communication within and outside of schools, unpreparedness of teachers and trainers to face and to solve challenges that are generating by immigrants and the host societies. The discussion is based on the preliminary results obtained during the implementation of the joint Ukrainian-Latv…
Comparison of effects on crustaceans: carbon nanoparticles and molybdenum compounds nanowires
Carbon nanomaterials (CNM) and molybdenum compound nanostructures are materials with various applications yet little is known regarding the toxicity of these nanoparticles in pristine form in aquatic environment. Daphnia magna standard acute toxicity test (EN ISO 6341:1996; freshwater) and Artemia salina standard acute toxicity test (ArtoxKit standard method; 15 ppt saltwater) were applied to assess the toxicity of non-modified CNM and molybdenum compound nanowires in water. It has been observed that CNM are more toxic in freshwater suspensions and somewhat more toxic than the tested molybdenum compound nanowires.
Vidusskolēnu izziņas aktivitātes veicināšana ar pētniecības uzdevumu palīdzību matemātikas mācībās
Darba mērķis ir izpētīt vidusskolēnu izziņas darbības veicināšanu, izmantojot pētniecības uzdevumus matemātikas mācībās. Pētījuma teorētiskajā daļā tiek analizēti: izziņas darbība no filosofijas, psiholoģijas un pedagoģijas aspektiem; vidusskolēnu vecumposms; pētniecības uzdevumu struktūra matemātikas mācībās un jautājums kā pētniecības uzdevuma daļa. Pētījumā tiek analizēta ESF projekta „Mācību satura izstrāde un skolotāju tālākizglītība dabaszinātņu, matemātikas un tehnoloģiju priekšmetos” pieredze pētniecisko uzdevumu izmantošanā atbalsta skolās un salīdzināta matemātikas mācību organizācija pētījuma grupā ar Lielbritānijā veiktā pētījumā iesaistīto divu skolu mācību organizācijas formām…
Variability in inorganic and organic nitrogen uptake associated with riverine nutrient input in the Gulf of Riga, Baltic Sea
Concentrations and rates of uptake of dissolved organic nitrogen (DON, free amino acids, and urea) and inorganic nitrogen (DIN, nitrate, and ammonium) were measured along two transects in the Gulf of Riga, a sub-basin of the Baltic Sea, during May and July 1996. Concentrations of total dissolved nitrogen (TDN) were 23±3 μg-at N 1−1 in the northern region (mouth) and 41±5 μg-at N 1−1 in the southern region (head) of the Gulf. Rates of nitrogen uptake, determined with15N-labeled substrates, reflected differences in TDN concentration between the regions. In May, uptake of DIN+DON measured 0.17 and 0.43 μg-at N 1−1 h−1 in the northern and southern parts of the Gulf, respectively. In July, DIN+D…
Toxico-resistance of Baltic amphipod species to heavy metals
Benthic organisms are important components of aquatic ecosystems and have been widely used to assess environmental pollution. Being very sensitive to a wide range of toxicants amphipods are often used as test objects in eco-toxicological studies. The aim of this study was to compare toxico-resistance of various Baltic amphipod species to exposure of heavy metals. The acute toxicity (48-h LC50 and 96-h LC50) of cadmium (CdCl2), copper (CuSO4) and zinc (ZnSO4 ⋅ 7H2O) was detected experimentally, using juveniles and adults of brackish water amphipods, Monoporeia affinis, Bathyporeia pilosa, Gammarus tigrinus, Pontogammarus robustoides and the freshwater amphipod Gammarus pulex as test objects.…