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In regions where groundwater forms the primary source of drinking water, comprehending the prospective availability of subsurface water resources due to climate change is of paramount importance.This study evaluates the impact of climate change on groundwater levels in the Baltic States until the end of this century. It employs link between surface and subsurface standardized indices. For forecast it uses various Representative Concentration Pathways (RCP) alongside different Regional Climate Models (RCM).By linking historical groundwater drought episodes with calculated surface drought indices and accumulation periods observed during defined climate Normals, we project groundwater levels for the short, medium, and long-term future. The study incorporates 13 EURO-CORDEX RCMs under three RCP scenarios.Our analysis reveals that, compared to the recent climate Normals, an overall increase in groundwater levels is expected at most study sites. However, lower groundwater levels are estimated in the near future. The projected impacts show no significant seasonal bias or spatial conformity. Although these findings are specific to the Baltic region, the methodologies described can be readily adapted for global application.

Biological wastewater treatment plants could serve as an important alternative to renewable biological nitrogen mines, which are locally available and have a low carbon footprint. Recent progress in Fenton processes has revealed their potential use for sludge treatment to decrease organic contamination and pathogens. The aim of this study was to determine the optimal concentrations of metal catalyst Fe(II) and hydrogen peroxide H2O2 for activated sludge (AS) disinfection using the Fenton process at near-neutral pH, alone and in combination with thermal treatment and UV radiation. The efficiency of the 48 h treatment was evaluated by log reduction, fluorescein diacetate (FDA) hydrolysis activity, concentration of pharmaceuticals, changes in antimicrobial resistance, and ecotoxicity. Using the desirability function approach, a combination of 239 mM H2O2 and 8.6 mM Fe(II) was found to be optimal in frames of the chosen concentrations of reagents. The FDA hydrolysis activity correlated with log reduction at 287 mM H2O2 and different Fe(II) concentrations. Sludge treatment resulted in the removal of ciprofloxacin by 65.5%. The sets with the highest log reduction, i.e., additionally treated by heating and UV, were accompanied by increasing ecotoxic effects on crustaceans, Thamnocephalus platyurus. The Fenton process shows prospective ways on sludge stabilization for its application as a fertilizer.

Traditionally, biosorbents have been used to remove contaminants from polluted water, such as wastewater, landfill leachate, rainwater or drinking water. However, two alternative uses of biosorbents have been proposed relatively recently: the removal of heavy metals from fruit juices by biosorption and the use of saturated biosorbents as animal feed. Because these biosorbents are in contact with food or are used as animal feed, the concentration of contaminants in biosorbents must be known. In addition, the characterization of biosorbents is crucial because biosorbent properties affect both adsorption efficiency and the performance of full-scale biosorbent systems. This article presents data from Fourier transform infrared spectroscopy (FTIR) analysis, and the concentration of toxic metals (determined by ICP-MS) as well as pesticide residues was determined in ten biomass samples, namely, pea skins, straw, seaweed Fucus vesiculosus, wheat bran, rye bran, raspberry seeds, peat, buckwheat husks, highbush blueberry pulp, and blackcurrant pulp. Selected biomass samples were also characterized by scanning electron microscopy (SEM), nitrogen physisorption analysis, and pyrolysis-gas chromatography-mass spectrometry (Py-GC/ MS/FID) analysis.

A new map and digital bedrock surface elevation model of Latvia is presented with a horizontal resolution of 250 m. The local bedrock comprises largely undisturbed layers of Palaeozoic and Mesozoic sedimentary rocks covered by up to 200 m thick Quaternary strata composed mostly of glacigenic and marine sediments. The bedrock surface elevation model and the corresponding map were created by tessellation interpolation of the bedrock surface based on more than 20,000 boreholes and constrained by the present land surface. The known locations of paleo-incisions buried under Quaternary cover are indicated. The new digital map has applications in hydrogeological, environmental, and civil engineering, and fundamental and applied research.

Benzalkonium chloride (BAC) is one of the most commonly used quaternary ammonium compounds in the pharmaceutical, cosmetic, and food industries. The aim of our study was to compare the physiological responses of Escherichia coli MSCL 332, Pseudomonas putida MCCL 650, and Staphylococcus epidermidis MSCL 333 on 50 mg/L BAC in rich and poor medium (100% and 5% tryptone soya broth (TSB)) in the temperature range from 8 °C to 37 °C, under static and shaking conditions. A high-throughput, 96-well microplate method was used to compare a broad range of cultivation conditions. The effect of BAC on growth, biofilm formation activity, and dehydrogenase and fluorescein diacetate hydrolysis activity was evaluated. Addition of BAC to 100% TSB inhibited biofilm formation at 37 °C by 2.4, 1.8, and 1.6 times for E. coli, P. putida, and S. epidermidis, respectively. In turn, BAC stimulated biofilm formation in E. coli in 5% TSB at 37 °C and 100% TSB at 8 °C, i.e., 1.4 and 1.3 times, respectively. Statistical optimization of broth composition with emphasis on biofilm formation and further testing under experimental conditions was performed with P. putida.

Study region: The Baltic region (Estonia, Latvia, Lithuania) located at the Eastern Shore of the Baltic Sea, Northern Europe. Study focus: The spatial and temporal distribution of groundwater drought events over the period 1989–2018 was examined. Standardized Groundwater level Index (SGI) was calculated for six monitoring wells installed into shallow unconfined or semiconfined aquifers evenly distributed across the region. A set of meteorological and hydrological drought indices were used to characterize drought events using data from EAR-5 reanalysis. New hydrological insights: Four major drought events affecting all six monitoring wells were identified: 1992–1994, 1996–1997, 2002–2004 and 2005–2007 with another episode apparently starting in 2018. Meteorological drought indices - Standardize Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), and Reconnaissance Drought Index (RDI) - showed the highest correlation with groundwater drought events. The ERA-5 parametrization of surface and subsurface runoff used to calculate the hydrological indices - Standardized Runoff Index (SRI) and Standardized Sub-surface Runoff Index (SSRI) - most likely did not adequately represent the hill-slope scale processes affecting the unconfined groundwater dynamics, thus indices SRI and SSRI showed less clear relationship with groundwater drought events. Different patterns of SGI fluctuations and correlation with other drought indices highlight the importance of localized meteorological, land use, geomorphological or geological factors in controlling the groundwater response to the atmospheric forcing.

Two years of monthly observations of water stable isotopes in a temperate lowland catchment with extensive agrarian and forested landscapes in Latvia, River Salaca catchment. Observations include most significant water types within catchment: precipitation, raised bog, intermittent, groundwater and surface water at 15 observation points. The monthly data is supplemented by two intervals of one-month long sampling every second day for a subset of observation points. Water table, temperature and electrical conductivity co-observed as key variables helping to understand the isotope data. The data can be useful for in depth investigation of isotope hydrology and as background information for ecohydrological and other studies. The data is associated with the original research article “An insight into water stable isotope signatures in temperate catchment” [1].

The importance of CO2 removal from the atmosphere has long been an essential topic due to climate change. In this paper, the authors aim to demonstrate the suitability of the underground reservoirs for CO2 storage based on their geological characteristics. The research addressed the potential of geological formations for fossil CO2 storage in the Baltic States to support the goal of achieving carbon neutrality in the region. The geological, technical, and economic feasibility for CO2 storage has been assessed in terms of carbon sequestration in geological structures and the legal framework for safe geological storage of fossil CO2. Results indicate that prospective structural traps in the Baltic States, with reasonable capacity for CO2 storage, occur only in Southwestern Latvia (onshore) and in the Baltic Sea (offshore), whilst other regions in the Baltics either do not meet basic geological requirements, or have no economically feasible capacity for CO2 storage. Based on the examination of geological characteristics, the most fitting is the middle Cambrian reservoir in the Baltic sedimentary basin, and one of the most prospective structural traps is the geological structure of Dobele, with an estimated storage capacity of 150 Mt CO2. This study revealed that the storage capacity of the middle Cambrian reservoir (up to 1000 Mt CO2) within the borders of Southwestern Latvia is sufficient for carbon capture and safe storage for the whole Baltic region, and that geological structures in Latvia have the capacity to store all fossil CO2 emissions produced by stationary sources in the Baltic States for several decades.