Abstract. The river delta regions are usually most vulnerable to flooding due to small changes in terrain elevation and river – sea interaction. The trends of increased frequency of flooding and an increased duration of the high water events are evident in many regions. In this study, we analyse the most extreme (severe) flood events in the Nemunas Delta region of Lithuania. The study focuses on the causes of floods and their changes over 1926–2016. Analysing specific case studies and comparing them with related studies of other researchers, we present an original interpretation of the variability of flood parameters. The aim of the study is to demonstrate that the analysis of flood events must be based on the identification of the drivers of individual floods. This is especially true for the lower reaches and the delta regions of rivers situated within the North European Plain. Historically, an intense melting of snow appeared to be the main cause of severe flooding in this region. The results of this study, however, show that the situation has rapidly changed over the last 30 years and large areas can be flooded even if the snow water equivalent over the whole basin is relatively low.
Keywords • extreme flooding • Lithuania • Nemunas River • severe water level
The paper presents a method for the selection of large erratics to be sampled for terrestrial cosmogenic nuclide exposure dating (TCNED) in areas previously covered by Pleistocene ice sheets. Our approach is based on (1) a GIS analysis of an extensive dataset of erratics, (2) field inspection of pre-selected boulders and (3) Schmidt hammer (SH) testing of erratics selected for sampling. An initial database of 491 erratic boulders in NW Poland was filtered using a GIS software, based on their characteristics, digital elevation and surface geology. The secondary data set of pre-selected erratics consisted of 135 boulders – i.e. proper targets for field inspection. Ground-truthing in the field resulted in the final selection of 63 boulders suitable for sampling for TCNED. These erratics are located on moraine plateaux and hills formed during the Saalian glaciation (Marine Isotope Stage 6) as well as Leszno/Brandenburg, Poznań/Frankfurt and Pomeranian Phase ice marginal belts from the Weichselian glaciation (Marine Isotope Stage 2). The GIS desk-based analysis of erratics properties resulted in a 73% reduction of the initial dataset, which demonstrates the added value of this selection technique. The field inspection of pre-selected boulders resulted in a 53% reduction of the number of boulders suitable for TCNED. SH testing of the sampled erratics provided a quantitative proxy of their surface hardness. This allowed the quantification of their weathering degree and identification of erratics potentially affected by postglacial erosion. Our systematic approach to selecting erratics and their SH testing could be a useful tool for other researchers facing the problem of choosing appropriate erratics for TCNED in areas of continental Pleistocene glaciations.
Keywords • erratics • terrestrial cosmogenic nuclide exposure dating • Schmidt hammer • Scandinavian Ice Sheet
In this study, we analysed the organic and inorganic content of the cryoconite holes along the altitudinal gradient at the lower elevations of the Russell glacier ablation zone in Southwest Greenland. We specifically focus on less studied industrial microscopic spheroidal carbonaceous particles (SCP; part of black carbon) to get more insights about their accumulation patterns on the glacier surface. We found no clear SCP distribution pattern, including concentration values. This outcome underlines the complexity of the ice margin zone and draws attention for further research on this topic with the inclusion of multiyear evaluation of SCP concentration at the even wider area that could possibly give results that can be compared to the emission source and long-way air pollution validation. In addition, our results indicate that during the summer of 2016, algae composition was formed of both green algae (Chlamydomonadaceae, Mesotaeniaceae) and cyanobacteria (Oscillatoriaceae). Green algae had a larger relative proportion than cyanobacteria in the cryoconite holes throughout the studied gradient.
Keywords • Arctic • Greenland Ice Sheet • spheroidal carbonaceous particles • mineral matter
A common problem in biogeochemical mapping and contamination studies is that the same plant species are not available everywhere. Filipendula ulmaria is a widely used indicator plant but it does not grow in dry and high altitude areas. We used different plant species (F. ulmaria, Carex species and Urtica dioica) and analysed the concentrations of Cd, Cu, Fe, Mg, Mn, Pb, Zn and P in the material from 19 sampling points in eastern Estonia. The geometric mean concentrations of Pb, Cd and Zn were similar in F. ulmaria and Carex, as were the dominating ranges of Cu, Mn and Zn. The geometric mean concentrations typically differ between F. ulmaria and U. dioica.
Simultaneous use of multiple indicator plants could generally not be recommended. Still, in case of urgent need the results could be amalgamated for the elements with more than 50% similarity of dominating ranges in different plants.
Keywords • AAS • ash • concentration • elements • heavy metals • biogeochemical mapping
Fragipan is a compacted but non-cemented subsurface horizon, considered as a pedogenic horizon, but the mechanism of its formation is not well understood. The main hydro-consolidation hypothesis involves a collapse of soil structure when it is loaded and wet, resulting a reorganisation of pore space. Soils with fragipan never have been marked in Russian soil maps. In the South Karelia, located in Eastern Fennoscandia (34.50921 E and 61.33186 N, 110 m asl) we studied a soil profile of Albic Fragic Retisol (Cutanic), developed in the glacial till of Last Glaciation with flat sub-horizontal topography under an aspen-spruce forest. The aim of this study was to demonstrate how the fragic horizon was formed in the Retisol located in South Karelia. Observations were made in each soil horizon using micromorphological method, particle size analysis and the study of mineralogical composition of clay fraction by X-ray diffraction. The analysis of the morphological description combined with the laboratory data have led us to the conclusion that the consolidation of the fragipan occurred after the textural differentiation of the profile, following the Atlantic Optimum, and does not depend on the presence of swelling clay minerals. The well-developed argic horizon was probably formed around 6000 years ago, under climatic conditions more favourable for clay illuviation than in present time. Fragipan is supposed to be developed during the Sub-Boreal cooling.
Keywords • soil genesis • illuviation clay • Holocene soil
The vertical borehole heat exchangers were surrounded by the heterogeneous multilayered geological environment and groundwater flow that affected the performance of borehole plants. In this paper, the field investigation of vertical borehole ground heat exchangers in capital city Vilnius (Visoriai), Lithuania is presented. The numerical heat transfer model considering seven different geological strata was developed using the cylindrical heat sink model for vertical borehole inside by solving the soil mass and heat transfer equations with groundwater flow. The numerical multilayered ground vertical borehole heat transfer model was calculated and validated by in-situ thermal response test data. The numerical model results were also compared with the homogeneous finite difference model expressed by the temperature response functions (well known as “g-functions”). The practical realization of g-functions was designed in the Earth Energy Designer as a practical tool for geoengineers designing the vertical borehole plants. The temperature profiles at borehole wall at different heating times were presented and explored together with relative errors. The numerical model will be used as a practical tool for the Lithuanian Geological Survey under the Ministry of Environment to estimate the underground conditions for the consumption of shallow geothermal energy.
Keywords • borehole ground heat exchanger (BHE) • in-situ experimental temperature response test (TRT) • multilayered ground • groundwater flow
Abstract The main goal of work was to quantify the nitrogen and phosphorus loads transported by small streams to the Gulf of Gdańsk. The research aims to determine wastewater release volumes over time, instead of focusing only on spatial distributions. Another aim is to identify the main determinants potentially affecting water quality in rivers flowing across the city of Sopot. The study area consists of six small river catchments located in the city of Sopot, each with an open flow channel, which lies along the bay. Studies were conducted 12 times per year in the period from March 2014 to February 2015. Laboratory analyses were performed to determine the concentration of both total nitrogen and total phosphorus. In order to calculate pollutant loads, discharge was also measured in each of studied rivers. Conducted research has shown that all analyzed streams were characterized by low total nitrogen and total phosphorus concentrations. The mean annual values ranged from 0.60 to 1.28 mg·dm-3 in case of total nitrogen and from 0.066 to 0.100 mg·dm-3 in case of total phosphorus. In 2012, the total nitrogen load from Poland to the Baltic Sea was 210.768.000 kg N while the total phosphorus load was 15.269.000 kg P, which means that streams analyzed in this paper supplied barely 0.002 % of the biogenic load supplied to the Baltic Sea by Poland as a whole.
Keywords • city of Sopot • the Gulf of Gdańsk • total nitrogen • total phosphorus • loads, water pollution
Abstract An analysis of the mineral-geochemical composition and structure of the Holocene–Pleistocene bottom sediments was performed on Lake Polevskoye, a small lake in the northern Lake Onega area in Russian Karelia, which is considered representative to describe the Late Weichselian Onega Ice Lake sediments. The analysis was accomplished using modern analytical methods, including scanning electron microscopy and ICP-MS, which allowed us to interpret their genesis in a new light. It is assumed that the distribution of rare earth elements (REE) in the bottom sediments of the recent Lake Onega and in the sediments of Onega Ice Lake will improve our understanding of the history of sedimentogenesis. It is apparent in the distribution of REE, their composition and data on the geochemical and mineral composition of the Holocene bottom sediments of Lake Onega and Lake Polevskoye (varved clays) that in their composition of terrigenous matter the material introduced from the north-western part of the catchment area is mainly composed of Archaean and Early Proterozoic crystalline complexes. However, the values of several indicator ratios of elements in the lower part of the of varved clays with shungite interlayers indicate the presence of mixing of clastic material from two sources of different geochemical origin: the north-western part of the catchment area (source of shungite rocks) and the south-eastern part of the catchment area (Phanerozoic sedimentary rocks of the Russian Platform).
Keywords • Onega Ice Lake • Lake Polevskoye • bottom sediments • varved clays • geochemistry • mineralogy • rare earth elements • scanning electron microscopy