The acute toxicity of CuO and ZnO nanoparticles in artificial freshwater (AFW) and in natural waters to crustaceans Daphnia magna and Thamnocephalus platyurus and protozoan Tetrahymena thermophila was compared. The L(E)C50 values of nanoCuO for both crustaceans in natural water ranged from 90 to 224 mg Cu/l and were about 10-fold lower than L(E)C50 values of bulk CuO. In all test media, the L(E)C50 values for both bulk and nanoZnO (1.1–16 mg Zn/l) were considerably lower than those of nanoCuO. The natural waters remarkably (up to 140-fold) decreased the toxicity of nanoCuO (but not that of nanoZnO) to crustaceans depending mainly on the concentration of dissolved organic carbon (DOC). The toxicity of both nanoCuO and nanoZnO was mostly due to the solubilised ions as determined by specific metal-sensing bacteria. Natural waters remarkably reduced the toxicity of nanoCuO but not nanoZnO.

This study reviews existing legal, institutional and policy tools and frameworks, relevant to the introduction and adoption of new marine litter clean-up technologies in two regional European seas, the Mediterranean and the Baltic. A combination of desk studies in six countries bordering the Baltic (Estonia, Germany, Sweden) and the Mediterranean (Greece, Italy, Tunisia), and interviews with experts and stakeholders, is used to identify key drivers and barriers to the adoption and diffusion of marine litter technologies. The main conclusion of the study is that the most influential pieces of legislation relevant to marine litter management are top-down EU policies, often forming the basis of regional and national plans. Moreover, the study finds that several drivers of marine litter technologies may at the same time be critical barriers. These factors include public awareness, consumer behaviour, enforcement of legislation, and the rise of SMEs engaged in recycling and eco-labelling of marine litter.

Recognizing the factors responsible for the gradual increase in greenhouse gas [e.g. carbon dioxide (CO₂)] emissions is crucial to reduce the detrimental consequences on environmental sustainability and human life. Accordingly, spotting the sectors which contribute the most to CO₂ emissions and dampen economic growth have become one of the major concerns for policymakers around the globe. Against this background, this paper examines the nexus between economic growth and CO₂ emissions in three Baltic countries namely Estonia, Latvia and Lithuania. Thus, the study basically checks the validity of the environmental Kuznets curve (EKC) hypothesis by taking into account the role of energy consumption and financial development over the period of 1990–2018. This type of study is highly important for the region in order to comply with the commitments of the Paris Agreement and Sustainable Development Goals of the United Nations. The study first employs appropriate testing procedures and second-generation panel data methods to account for cross-sectional dependency and slope heterogeneity among countries. Applying unit roots and cointegration tests, the study then employed different mean group estimation models and heterogeneous panel causality methods suitable for cross-sectionally dependent and heterogeneous panels. The results of the econometric analyses reveal that the inverted U-shaped EKC hypothesis does not hold in the Baltic countries. But the pollution haven hypothesis is evidenced to hold for these nations. By boosting the CO₂ emissions figures, again, the study also revealed that higher levels of energy consumption exhibit adverse environmental consequences. Financial development is found to be effective in explaining the variations in the CO₂ emission figures of the selected countries as well. Causality test results confirm bi-directional causality between economic growth and CO₂ emissions, energy use and CO₂ emissions, CO₂ emissions and financial development, energy use and economic growth as well as between energy use and financial development. Furthermore, country-specific impacts are found to be similar to the corresponding panel estimates. Consistent with the findings, the study finally puts forward some policy-level suggestions. Accordingly, it is recommended that the Baltic countries need to move away from fossil-fuel dependent energy consumption growth policies to mitigate environmental degradation.

Monitoring heavy metal contaminants in fish is important for the assessment of environmental quality as well as food safety. In this study, European eel samples were collected from Lake Köyceğiz and Lake Võrtsjärv in 2017 and 2018. The concentrations of Mn, Cd, Zn, Pb, and Cu metals were measured by using GF-AAS in four selected tissues of eel, including liver, gill, skin, and muscle in both lakes. The pollution index (Pᵢ, MPI) values were calculated for both lakes and the health risk for consumers was assessed for both adults and children in Turkey and Estonia. The estimated weekly intake (EWI), hazard index (HI), and lifetime cancer risk values (CRs) for the metals were calculated for both lakes. According to the results of this study, a significant difference was determined between the metal concentrations (especially Cu, Cd, and Pb) in the tissues of the eel samples taken from the two lakes. These results show that besides the pollution levels in the aquatic environment, physiological needs and metabolic activities in different habitats have a significant effect on metal accumulation in eels. In addition, HI was found to be < 1 for both adult and child consumers in both lakes, which indicates that consumers would not experience non-carcinogenic health effects. However, the values of CR for Pb and Cd were found negligible in Lake Köyceğiz, while the CR value for Pb was found to be very close to the danger limits in Lake Võrtsjärv.

In this study, we evaluated the needle anatomy of Norway spruce trees growing on a territory that was exposed to different alkaline dust pollution. The anatomy of the needles of spruce growing on a polluted site in the vicinity of the Kunda cement plant (Northeast Estonia) was compared with the anatomy and physiological state of the needles from an unpolluted site. The needles from polluted sites had a significantly larger average mesophyll area and thicker epidermis. These needles also had significantly smaller average vascular bundles and xylem areas than needles from the unpolluted site. Although in the alkalised growth conditions, the mesophyll area enlarged, the number of damaged mesophyll cells increased, and as a result, the concentration of chlorophylls decreased reducing the photosynthetic potential of trees. Our study indicates that even though cement dust pollution has practically ceased in the area, the alkalised soil is affecting physiological processes in trees for a long time.

The effects of alkaline dust emitted from a cement plant for over 40 years on the anatomy of needles of Scots pine and lignin accumulation were analysed. Comparative analytical studies were conducted in stands similar as to their silvicultural indicators, climate and age in alkalised and in a relatively unpolluted area. Cross-section of needles were stained, photographed under microscope and measured. It was found that, due to the alkalisation of the environment, the total area of the needle cross-section, needle width and thickness and the area of mesophyll had decreased. At the same time, the vascular bundles and epidermis had increased. The greatest anatomical and biochemical differences between the needles from trees growing under optimum conditions and in the alkalised area were observed in the oldest needles. Visual analysis of cross-sections and biochemical analysis showed accumulation of lignin in older needles but more intensively in alkalised areas than in control.

The impact of long-term dust pollution emitted from a cement plant on soil chemistry, and the concentrations of plant nutrients, lignin, cellulose and hemicellulose in the stemwood of 80–85-year-old Pinus sylvestris was investigated at different distances from the emission source. It was found that alkaline cement dust (pH 12.3–12.6) emissions for over 40 years resulted in an alkalisation (pH 6.7–7.9) of the polluted soil compared to a pH value of 3.8 in unpolluted soil. There were also nutrient imbalances in the soil, as well as certain disturbances in mineral nutrition processes and accumulation of nutrients in the tree stems. The average concentrations of K, Ca and Mg in stems were higher and those of N and P lower than in the unpolluted area. The lignin (L) content in stemwood increased, hemicellulose (Hc) decreased, while cellulose (Ce) did not change. A variation in the partitioning of L, Ce, Hc and nutrients between different sections of stems and between trees from different sample plots was found. L, Ce and Hc were not related to the internal K, Ca and Mg concentrations. Correlations were established between L, Ce, or Hc content and C content, and between L and Hc content in stem tissues. The contents of wood components were not related to N or P in the alkalised areas, but seemed to be more associated with P than with N. Alterations in the arbitrarily chosen ratio L/(Ce + Hc) indicated changes in wood quality, and a negative correlation with N/P was found in stem tissue in the polluted area, while positive correlations with N/Mg and Ca/Mg were found in the control area.

The influence of alkaline dust pollution (pH of water solution of dust 12.3–12.7) from a cement plant (Kunda town, Estonia) on chlorophylls and carotenoids of the needles of 60–80 year old Norway spruce was studied on sample plots established at different distances from the emission source. The highest sensitivity to dust impact was measured in the content of Chl a, Chl b, carotenoids and elements regulating or participating in the biosynthesis of pigments (Mg, Fe, N, Mn).

Dust pollution can cause a significant damage of environment and endanger human health. Our study aimed to investigate epiphytic lichens and bryophytes in relation to long-term alkaline dust pollution and provide new insights into the bioindicators of dust pollution. We measured the bark pH of Scots pines and the species richness and cover of two cryptogam groups in 32 sample plots in the vicinity of limestone quarries (up to ca. 3 km) in northern Estonia. The bark pH decreased gradually with increasing distance from quarries. We recorded the changes in natural epiphytic communities, resulting in diversified artificial communities on pines near the pollution source; the distance over 2 km from the quarries was sufficient to re-establish the normal acidity of the bark and natural communities of both lichens and bryophytes. The cover of lichens and the number of bryophytes are a more promising indicator of environmental conditions than individual species occurrence. We confirmed previously proposed and suggested new bioindicator species of dust pollution (e.g., Lecidella elaeochroma, Opegrapha varia, Schistidium apocarpum). Limestone quarrying activity revealed a “parapositive” impact on cryptogamic communities, meaning that quarrying might, besides disturbances of natural communities, temporarily contribute to the distribution of locally rare species.