The paper presents a pioneer in Quaternary geology, both internationally and in Scandinavia – the Swedish geologist and professor Gerard De Geer (1858–1943). This is done, first by highlighting one of his most important contributions to science – the varve chronology – a method he used to describe the Weichselian land–ice recession over Scandinavia, and secondly by the re–publication of a summary article on Gerard De Geer’s early scientific achievement in 1881–1906 related to the Baltic Sea geology, written by his wife, Ebba Hult De Geer.
Keywords: Gerard De Geer; Clay varves; Varve chronology; Glacial and Postglacial; Quaternary geology; Baltic Sea
The Gulf of Finland is known to have been under rather hard stress from the anthropogenic loading of harmful substances for many decades. The emissions are known to have decreased slightly during the last two decades, but can that decrease be seen also in the sea floor sediments? In this study, heavy metal data from the early 1990s are compared with new research data from 2007–2009. Concentrations of most metals have decreased in the sea floor sediments through the last one and one-half decade. The situation is improving in general despite a drawback on cadmium; those concentrations have remained at levels much too high, with virtually no decrease in trend through the years. Lead and mercury on the other hand seem to have decreased even more than expected, which is a very good sign, given the harmfulness of these metals.
Keywords: Heavy metals; Distribution; Arsenic; Carbon; Environment; Contamination; Pollution; Sediment; Gulf of Finland
The different conceptions of wetlands and their classifications as well as their definitions in Lithuania are represented in this paper. According to existing databases, Lithuanian wetlands are represented by: suo wetlands, peatlands, lentic, lotic, and marine/coastal wetlands. The harmonisation of the Ramsar classification system with the traditional classifications of Lithuanian wetlands is emphasised. The distribution of the distinguishable wetland types is identified. The following Ramsar inland and man-made wetland types are found in Lithuania: non-forested and forested peatlands (9.9 %area of Lithuania), seasonal pools on mineral soils and tree-dominated wetlands (>13.92% area of Lithuania), permanent freshwater lakes (1.27% area of Lithuania), permanent freshwater marshes/pools (0.08% area of Lithuania), aquaculture ponds (0.18% area of Lithuania), ponds (0.16% area of Lithuania), water storage areas (0.3% area of Lithuania), excavations (0.04% area of Lithuania), permanent rivers/streams/creeks, seasonal streams/creeks (~0.69% area of Lithuania), canals and drainage ditches (0.11% area of Lithuania), and permanent inland deltas (0.01% area of Lithuania). The authors identified the following types of Ramsar marine/coastal wetlands in Lithuania: permanent shallow marine waters (0.09% area of Lithuania), sand, shingle or pebble shores (94 km marine and 77.89 km lagoon shores), coastal freshwater lagoons (0.52% area of Lithuania).
Keywords: Ramsar wetlands type; Wetlands classification; Lithuanian wetlands
An analysis of changes in the coastline of the Nemunas River delta front was undertaken with GIS based on cartographic material representing a 95 year period. Delta development was analysed comparing two time periods: 1910–1958 and 1958–2005. Quantitative indicators of land area determined during the study indicate that land in the northern part of the Nemunas delta front decreased more than 2.1 times in the 1958–2005 period, compared to the previous 1910–1958 period. The main reasons for the decrease of sediment accumulation are a decrease Nemunas River runoff, and a similar decrease of sediment particulates, due to anthropogenic activity and natural factors a rise in the water levels of the Baltic Sea and the Curonian Lagoon, as well as land subsidence in the Nemunas delta region.
Keywords: Nemunas delta front (avandelta); Runoff; Sedimentation; Inundation; Sea level rise; Lithuania
Baltic Sea water exchange is primarily governed by atmospheric forcing of the inflow of saline waters by strong westerly winds prevailing over the central North Atlantic and north-western Europe. Our sediment core study uses geochemical element records indicative of phytoplankton and cyanobacterial blooming as well as continent-derived mineral input for reconstructing hydrographic changes in the deeper Baltic Sea basins around AD 1200. An alkenone-based Sea Surface Temperature (SST) reconstruction for the relevant time span, AD 500–1500, is presented for another sediment core obtained from the shallow Isefjord located at the southern coast of the Kattegat at the entrance of the Baltic. At the termination of the Medieval Climate Anomaly at approximately AD 1200, the basin sediment facies and the geochemical records reveal an environmental change indicative of a marked decrease of inflow activity and marine productivity. This change coincides with a SST decrease and recently reported general fall in Kattegat sea level. A comparison with palaeo-climate data from the wider North Atlantic region demonstrates that this regime shift in Baltic Sea water exchange is linked to a large-scale change in ocean and atmosphere circulation from a dominating, positive North Atlantic Oscillation (NAO+) mode to more negative NAO conditions.
Keywords: Saline inflow; Marine productivity; Medieval Climate Anomaly; Sediment cores; Geochemistry; Baltic Sea
Water temperature is one of the twelve physico–chemical elements of water quality, used for the assessment of the ecological status of surface waters according to the Water Framework Directive (WFD) 2000/60/EC. The thermal regime of Lithuanian rivers is not sufficiently studied. The presented article describes the temporal and spatial variation of water temperature in Lithuanian rivers. Since a huge amount of statistical data is available (time series from 141 water gauging stations), the average water temperatures of the warm season (May–October) have been selected to analyse because that is the time when the most intensive hydrological and hydro–biological processes in water bodies take place. Spatial distribution of river water temperature is mostly influenced by the type of river feeding, prevalence of sandy soils and lakes in a basin, river size, and orography of a river basin as well as anthropogenic activity. The temporal distribution of river water temperature is determined by climatic factors and local conditions. The averages of the warm season water temperature for 41 WGS are 15.1°C in 1945–010, 14.9°C in 1961–990, and 15.4°C in 1991–010. The most significant changes in water temperature trends are identified in the period of 1991–010. For this period, the rates of increase of water and air temperature are 0.04 and 0.06°C/warm season, respectively. Therefore, air temperature is one of the most significant factors affecting the water temperatures of Lithuanian rivers.
Keywords: Water temperatur; Spatial distribution; Trends; Lithuanian rivers
The aim of this study was to reveal the patterns of structural and quantitative alterations of the plankton communities along the Nemunas River–Curonian Lagoon transition of the south-eastern Baltic Sea. Authors hypothesised the influence of the different phases of the seasonal plankton development (Bacillariophyceae vs. Cyanobacteria dominance) on the response of plankton communities due to hydrodynamic forcing. In order to assess spatial patterns of physical forcing, we used sediment grain size distribution data as a proxy for hydrodynamic regime. Zooplankton and phytoplankton communities in the Nemunas River were sampled to obtain a point of reference for their structure and seasonal dynamics. The changes in sediment grain size distributions, quantitative and structural alterations in zooplankton communities, as well as structural trends in phytoplankton communities were detected in the Nemunas River–Curonian Lagoon transition area. However, the expected abundance trend was not observed in the phytoplankton community, even during the Cyanobacteria–dominated period. Despite the observed gradient of the sediment structure along the river–lagoon transition, the expected value of the sediment characteristics for the pelagic conditions was not statistically proved.
Keywords: Plankton communities; River-lagoon transition; Sediment structure; Curonian Lagoon; Lithuania
A brief report highlights the progress made during the 1st phase of the EMODnet–Geology Project (2009-2012). The project aims to bring togheter marine geological information from the European seas. All public available data on the sea-bed sediments, seafloor geology, geological boundaries and faults, rate of coastal erosion and sedimentation, geological events and event probabilities, seismic profiles; and minerals including aggregates, oil and gas have been compiled into the map layers at 1:1 million scale stored on the OneGeology-Europe portal (http://www.onegeology-europe.org/home.html). The project area covered the Baltic Sea, Greater North Sea and Celtic Sea; however, the EC have extended the geographical area of the programme to include, for example, the Mediterranean and Black seas, and have increased the resolution of compiled information to 1:250 000 scale.
Keywords: Marine observation; Data network; Geology; Environment; Sediment; European seas