Percolation increased by 19.0, 22.3, and 20.1% during the spring, autumn, and winter, respectively, and decreased by 35.0% in summer. The annual percolation increased by 14.2% over 2011–2020 compared to 1989–1998. The number of rainy days did not change during the year, but the frequency of heavy precipitation increased significantly in August. In autumn, the amount of precipitation decreased by 7.9–31.1 mm. Precipitation increased the most in July and August (10.9 and 22.9 mm). The distribution of yearly precipitation has changed, with the annual amount decreasing from 686 to 652 mm. The air temperature has increased significantly in November (+3.4 ☌) and December (+3.3 ☌), with a +2.2 ☌ increase in the standard climate normal. Two 10-year periods, 1989–19–2020, were selected from the whole observation period (1987–2022) to assess changes in precipitation infiltration due to climate change. Data from 1987–2022 research (n = 1296) was used to determine trends in precipitation infiltration changes. The aim of this paper is to identify the trends of changes in atmospheric precipitation percolation under the changing climate conditions of Lithuania (the East Baltic region) based on long-term lysimeter studies. Further, the total yearly load of DSi from two major rivers (Vistula and Oder) and from the sediments, to the southern Baltic Sea reaches 258 kt y⁻¹ of which benthic fluxes may constitute up to 34%. In all studied environments (enclosed lagoons, open bay, and open coastal zone) DSi benthic fluxes represent an important component of the marine Si cycle. Generalized Linear Models indicated that in shallow enclosed areas biological factors, particularly presence of Chironomidae larvae, explained DSi fluxes variation while in open areas the environmental factors, such as organic matter quantity and quality, were key explanatory variables. Sediments with high mud content had the highest fluxes in autumn, intermediate in spring, and the lowest in winter whereas no clear patterns were detected for sandy sediments. Obtained benthic fluxes ranged from the uptake of −1.11 mmol m⁻² d⁻¹ in summer to a release of 6.79 mmol m⁻² d⁻¹ in autumn, while in situ concentrations in the bottom water were the lowest in autumn (0.7 μmol L⁻¹) and the highest in winter (up to 58.0 μmol L⁻¹). Measurements were performed using ex situ incubations of sediment cores with natural benthic assemblages. Spatial and seasonal changes in benthic fluxes of dissolved silica (DSi) across the coastal zones were investigated in the southern Baltic Sea. The establishment of a database on the environmental parameters in the benthic environment and their role in the distribution of benthic organisms will help monitor the benthic environment and its health. Sediment composition is also interconnected to the complex relationship of other parameters with benthos besides contaminants. Salinity, dissolved oxygen concentration, temperature, depth, latitudinal variations, level of nutrients, and turbidity directly and indirectly influence the distribution, abundance, and larval survival of benthos as well as food availability among benthic organisms. Benthic assemblages encompassing macro and meiobenthos in all the regions including intertidal (soft and rocky), estuarine, coastal and deep seas occurring in different substrata are tied to the interplay of the environmental parameters. This chapter presents information on the influence of major physicochemical factors including depth, temperature, salinity, turbidity, sediment texture, dissolved oxygen, pH, nutrients, organic matter, redox potential index, and contaminates on the marine benthos. Managing coastal ecosystems to improve the effectiveness of the coastal filter can reduce eutrophication in the open Baltic Sea. Moreover, these processes are strongly modulated depending on composition of vegetation and fauna. Organic matter processes are tightly linked to the nitrogen and phosphorus cycles. Phosphorus burial is high in archipelagos with substantial sedimentation, but the stability of different burial forms varies across the Baltic Sea. Nitrogen removal through denitrification is high in lagoons receiving large inputs of nitrate and organic matter. This review investigates the most important processes for removal of nutrients and organic matter, and the factors that regulate the efficiency of the coastal filter. This diversity is also reflected in the importance of different biogeochemical processes altering nutrient and organic matter fluxes on the passage from land to sea. The coastal zone of the Baltic Sea is diverse with strong regional differences in the physico-chemical setting.
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