Abstract During the blooming season, algal colonies can, in extreme cases, cover up to 200 000 square kilometres of the Baltic Sea water surface. Because the position and shape of the blooms may significantly change in a very short time due to the influence of wind and waves, regular monitoring of the blooms’ development is necessary. Currently, the desired monitoring frequency may only be achieved by means of remote sensing. The article presents a novel method of AVHRR data processing for the purpose of detection of algal blooms in the Baltic Sea. Instead of analysing the value of spectral reflectance of the algae, the algorithm analyses the frequency distribution of normalized difference in reflectance between the visible and near-infrared spectral bands. The proposed method has been implemented and tested as part of an operational Geographic Information System.
Raktažodžiai GIS, algae, AVHRR, remote sensing, geovisual analytics
Abstract The article presents a study of the physico-chemical properties of fen peat and their influence on the metal accumulation patterns in three Latvian fens: Svētupes Mire, Elku Mire and Vīķu Mire. Full peat profiles were obtained at all study sites and analysed with a multi-proxy approach. The content of metals in fen peat was determined using the atomic absorption spectroscopy (AAS) and normalised to the concentration of Ti in the studied peat profiles. Both the character of deposits and agricultural land use in the mire catchment areas were taken into account and the possible natural and anthropogenic metal supply sources were evaluated. The content of metals in the studied fen peat significantly varied due to the heterogeneity of fen environment; however, noticeable similarities were also traced throughout all study sites. The results indicate an increased amount of transition metals and Pb in the upper peat layer. This can be explained by a direct impact from anthropogenic sources (agricultural land use, pollution, etc.). Metal binding in fen peat profiles is directly related to the alkali and alkaline earth metal content in peat, as Ca, Mg, Na and K ions are replaced by more tightly bound metal ions. In raised bogs, in turn, metal binding is associated with the acidic functional groups common to peat.
Raktažodžiai fen peat, metals, peat physico-chemical properties
Santrauka Abstract The article presents data on influence of non-operational landfills located in different hydrogeological systems on Lithuania groundwater quality. The landfills are located in open, semi-open, semi-closed and closed hydrogeological systems. The prevailing values of total dissolved solids (TDS) in the most intensive groundwater pollution zones of landfills can be divided into four TDS levels: low (400–3000 mg/l), moderate (TDS 3000–5000 mg/l), high (TDS 5000–20000 mg/l) and very high (TDS 20000–32000 mg/l). Groundwater with a low TDS level prevails in the most intensive groundwater pollution zones of landfills in open and semi-open hydrogeological systems. Groundwater with high and very high TDS levels characterizes about 3% of landfills in open and semi-open hydrogeological systems. The landfills in semi-closed and closed hydrogeological systems are also characterised by groundwater with a low TDS level. No landfills with a very high TDS level were found in semi-closed and closed hydrogeological systems.
Raktažodžiai landfills, classification, hydrogeological systems, pollution, hierarchical cluster analysis
Abstract The article presents a short historical review of development of marine geology at the Geological Survey of Finland (GTK). The founder of the marine geology unit at GTK, Dr. Heikki Ignatius, established at an early stage good relations with the Baltic Sea researchers of neighbouring countries. This resulted in joint research cruises, exchange of ideas and close cooperation. The purpose of this article is to highlight some of the important steps taken at GTK and to show how cooperation has resulted in the investigations of the Baltic Sea becoming one of the best studied sea areas in the World Ocean.
Raktažodžiai marine geology, marine survey technique, history of oceanography
Abstract Our recent knowledge of the chemistry of the seafloor of the Baltic Sea has been gained during the last century only and most of it during the last three to four decades. When thinking about the start of the industrialization it seems unfortunately late. However, fortunately the seafloor archives all environmental changes in the sedimentary column like pages in a book and they can be later observed and interpreted. The Geological Survey of Finland has performed seabed geochemistry studies for decades. The first studies were performed onboard cruises of the old research vessel Aranda and later on the new Aranda as well as on the surveys on our own vessels Geola, Kaita, and Geomari. A great part of the work has been done as collaboration in international research programmes, but especially the Marine Ecogeological Patrol by the A. P. Karpinsky Russian Geological Research Institute has been of great importance for Gulf of Finland studies and as a trigger for later studies in the Gulf of Finland as well as the Baltic Sea.
Raktažodžiai geochemistry, methods, sampling, 137Cs dating, sediment
Abstract A multi-indicator paleolimnological study of sediments from Lake Ķūži (central Latvia) was used to obtain a comprehensive record of environmental changes in the Holocene. Periodicity in the changes and the main drivers (lake basin development, catchment properties, climate, human activities) of the sedimentary record was studied. In order to comprehend the whole-lake sedimentation during the Holocene, a detailed multi-indicator record from the central part of the lake was integrated with records of sediment mass accumulation rates from four cores from different parts of the lake and a GPR (ground-penetrating radar) survey of the lake basin. The observed changes in the sedimentation regime that took place during the early Holocene are strongly linked with variations in climatic conditions, but the catchment and lake basin also played an important role. In the middle Holocene the water level was stable and the lake was influenced by climate mediated through changes in the catchment vegetation. Around 5 000 cal. BP sedimentation pattern changed, and three of the four main drivers made a comparably strong impact on the sedimentary signal. Since 2 000 cal. BP multiple indicators point to a major disturbance clearly related to human activity, which conceals the impact of the natural drivers.
Raktažodžiai sedimentary signal, lake basin, catchment properties, climate, human impact, multi-proxy