Tanskanen, N. & Ilvesniemi, H. 2006: Cation-exchange reactions involving aluminium ions in podzols disturbed by deep tilling. Boreal Env. Res. 11: 81–93.

The stratified structure of a podzolic soil is changed during deep tilling of forest soils. Here, we assessed whether (i) cation-exchange properties and (ii) cation-exchange reactions in podzolic soil were altered when the illuvial (B) horizon was subject to environmental conditions prevailing on the soil surface and the organic (O) horizon was buried within the mineral soil. The samples were taken from undisturbed and disturbed podzolic soil profiles at two forest sites that had been ploughed 17 and 31 years ago and planted with Norway spruce seedlings. An increase in soil organic C and effective cation-exchange capacity (CEC_e) was observed in the Bs horizons exposed to the soil surface. The accumulation of soil C was mainly due to organic matter produced by the planted Norway spruce. The Al³⁺-Ca²⁺ cation-exchange equilibria were similar in both the disturbed and undisturbed O and Bs horizons. This indicates that similar reactions between Al³⁺ and Ca²⁺ took place in different horizons of podzols irrespective of the disturbance. A positive correlation of CEC_e in the Bs horizons with soil C indicated that soil organic matter played a major role in the cation-exchange reactions. The importance of exchangeable cations in determining pH variation in the O horizon was additionally supported by the success in describing the relationship between soil solution pH_s and base saturation using the extended Henderson-Hasselbach equation in which exchangeable Al_e had nonacidic properties similar to those of base cations. The results of this study suggest that organic matter, accumulated within the soil profile during soil formation and upon ploughing, had an important role in determining the cation-exchange properties and reactions in the studied podzols.

Mattila, J., Kankaanpää, H. & Ilus, E. 2006: Estimation of recent sediment accumulation rates in the Baltic Sea using artificial radionuclides ¹³⁷Cs and ^239,240Pu as time markers. Boreal Env. Res. 11: 95–107.

This study reviews sediment data obtained from the Baltic Sea from 1995–2003. Recent sediment accumulation rates (SAR) were estimated at 69 stations in the Baltic Sea from 99 sediment cores using concentration peaks of ¹³⁷Cs and ^239,240Pu as time markers of the years 1986 and 1963, respectively. SAR values varied widely between 60–6160 g m^–2 yr^–1. The highest SAR values were observed at stations in the northern part of the Bothnian Sea, river estuaries and the eastern part of the Gulf of Finland. Generally, the SAR (median) of stations in the Bothnian Sea was two times higher than values in the Gulf of Finland or the Bothnian Bay, and about seven times higher than in the Baltic Proper. A strong correlation was detected between the SAR and total ¹³⁷Cs activities. The usability of estimation methods has been considered and, e.g., unstable sedimentation could limit the use of radionuclides in sediment dating and estimation of the SAR at stations in the Baltic Sea.

Dailidiene, I., Davuliene, L., Tilickis, B., Stankevicius, A. & Myrberg, K. 2006: Sea level variability at the Lithuanian coast of the Baltic Sea. Boreal Env. Res. 11: 109–121.

The aim of the paper is to analyse the sea level variability at the Lithuanian coast during the last 100 years using all data available in Lithuania. The analysis, based on sea level data of the Klaipeda Strait for 1898–2002, clearly shows that the long-term sea level increased by about 13.9 cm. Furthermore, it is remarkable that the increase is not found to be linear during the study period. Only a negligible increase is found at every Lithuanian tide gauge until World War II. Starting from the middle of the last century the increase in sea level is more pronounced having a rate of about 3 mm per year since the 1970s. This rise leads to manifold practical problems concerning activities in the coastal areas. The water rise will intensify the intrusion of salty water into the Curonian Lagoon slowly changing the ecosystems in its northern part. The reasons behind this rise are related to enhanced and more frequent advection of warm and moist maritime air masses during the cold season (October–March). This is coupled with intensified air flow from the west with increasing air temperatures followed by rise in water temperatures and thermal expansion of sea water, the global rise of the sea level also playing an important role. The annual mean sea level fluctuation is found to be linked with the winter North Atlantic Oscillation (NAO) index. When the NAO index is positive during winter, the dominating and enhanced westerly flow across the North Atlantic advects relatively warm maritime air over northern Europe. These strong westerly winds cause more frequent flooding events in the southeastern part of the Baltic Sea at the Lithuanian coast.

Suursaar, Ü., Jaagus, J. & Kullas, T. 2006: Past and future changes in sea level near the Estonian coast in relation to changes in wind climate. Boreal Env. Res. 11: 123–142.

The dependence of sea level on past and future climatological conditions is investigated in nearly tideless semi-enclosed sub-basins of the Baltic Sea using trend analysis of the tide gauge data for the period of 1924–2003 and hydrodynamic modelling. The results suggest that in addition to the effect of eustatic rise in mean sea level and its partial compensation by isostatic land uplift, the water level has risen by up to 6 cm near the Estonian coast during the last fifty years, probably due to changes in wind climate. The sea-level increase was concentrated in the period from November to March. It is in good correlation with increasing trends in local storminess and in higher intensity of westerlies, as described by AO and NAO indices. For the future sea level, a set of sensitivity and scenario runs considering possible future changes in wind climate was performed using a 2D hydrodynamic model with a 1-km grid-step. The scenario runs show that if the intensity of westerlies continues to grow (with less than 20% annual mean wind speed increase) the local annual mean sea level rise up to 5–6 cm can occur in some windward bays of the Gulf of Riga. The rise can be up to 9–11 cm in winter months, while in summer the sea level rise is unlikely. Also, increase in variability and extremes can be expected.

Suursaar, Ü., Kullas, T., Otsmann, M., Saaremäe, I., Kuik, J. & Merilain, M. 2006: Cyclone Gudrun in January 2005 and modelling its hydrodynamic consequences in the Estonian coastal waters. Boreal Env. Res. 11: 143–159.

Meteorological parameters of windstorm Gudrun on 8–9 January 2005 and its hydrodynamic and environmental consequences are analysed on the basis of observational data and hydrodynamic modelling. The study focuses mainly on describing events and reception in Estonia. We estimate that in meteorological terms, the cyclone was among the five most powerful ones in recorded history. Considering also the new highest storm surge record (275 cm in Pärnu), extensive property damage and massive media coverage, it became the most influential natural disaster in Estonia. Using a shallow sea 2D hydrodynamic model with a 1-km grid step, a hindcast modelling study of the sea level was carried out. Hydrodynamic simulations suggest that an inflow of 24 km³ (5.4% of the Gulf's average volume) occurred in the Gulf of Riga. The sub-basin of the Väinameri was nearly entirely flushed through by more saline and nutrient-poorer water from the Baltic Proper. The simulated current velocities, sea levels and wave parameters indicate that prominent coastline changes and replacement of sediments could have occurred within a single day.