Climate variability in SE Europe since 1450 AD based on a varved sediment record from Etoliko Lagoon (Western Greece)

To achieve deeper understanding of climate variability during the last millennium in SE Europe, we report new sedimentological and paleoecological data from Etoliko Lagoon, Western Greece. The record represents the southernmost annually laminated (i.e., varved) archive from the Balkan Peninsula spanning the Little Ice Age, allowing insights into critical time intervals of climate instability such as during the Maunder and Dalton solar minima. After developing a continuous, ca. 500-year-long varve chronology, high-resolution μ–XRF counts, stable-isotope data measured on ostracod shells, palynological (including pollen and dinoflagellate cysts), and diatom data are used to decipher the season-specific climate and ecosystem evolution at Etoliko Lagoon since 1450 AD. Our results show that the Etoliko varve record became more sensitive to climate change from 1740 AD onwards. We attribute this shift to the enhancement of primary productivity within the lagoon, which is documented by an up to threefold increase in varve thickness. This marked change in the lagoon's ecosystem was caused by: (i) increased terrestrial input of nutrients, (ii) a closer connection to the sea and human eutrophication particularly from 1850 AD onwards, and (iii) increasing summer temperatures. Integration of our data with those of previously published paleolake sediment records, tree-ring-based precipitation reconstructions, simulations of atmospheric circulation and instrumental precipitation data suggests that wet conditions in winter prevailed during 1740–1790 AD, whereas dry winters marked the periods 1790–1830 AD (Dalton Minimum) and 1830–1930 AD, the latter being sporadically interrupted by wet winters. This variability in precipitation can be explained by shifts in the large-scale atmospheric circulation patterns over the European continent that affected the Balkan Peninsula (e.g., North Atlantic Oscillation). The transition between dry and wet phases at Etoliko points to longitudinal shifts of the precipitation pattern in the Balkan Peninsula during the Little Ice Age

A novel bentonite humic acid composite material BephosTM as an environmental-friendly tool in phosphate and ammonium management

The objective of the present study was to examine the feasibility of using a novel modified bentonite as adsorbent for phosphate and ammonium removal from natural eutrophic waters. The uptake of phosphate and ammonium in adsorption kinetics A critical parameter was the initial phosphate concentration aiming to represent a eutrophic natural ecosystem. Moreover, its adsorption capacity and efficiency as a restoration tool was compared with a number of materials tested on the removal of phosphate and ammonium from aqueous solutions. Bephos™ is capable for simultaneous adsorption of both phosphorus and ammonia and this is an important advantage against other materials used to restore eutrophic water bodies. Adsorption kinetics showed that more than 90% and 70% removal of phosphate and ammonium respectively from water within 30 min. Bephos™ is potent for remediation of phosphate and ammonium at low concentrations that occur in natural water ecosystems

Ecosystem response to human- and climate-induced environmental stress on an anoxic coastal lagoon (Etoliko, Greece) since 1930 AD

To better constrain the effects of anthropogenic impact on coastal wetlands with respect to natural variability, we here analyze annually laminated sediments from Etoliko lagoon (western Greece, Mediterranean Sea) spanning the last*80 years. Subdecadal- scale palynomorph (pollen and dinoflagellate cyst) and seasonal-scale palynomorph (microfacies and l-XRF) analyses were carried out to investigate the evolution of the aquatic environment and the surrounding terrestrial ecosystem. Based on a robust age model, which was developed using varve counting and 137Cs dating, our results indicate that land-use changes have altered the vegetation dynamics and led to eutrophication of the aquatic environment particularly from the early 1980s onwards. In agreement with instrumental data and reports of fish mass mortality events, our varve composition and high-resolution element scanning data suggest that the ecosystem has been under unprecedented pressure since 1990 AD. In particular, the enhancement of anoxic conditions due to human-induced eutrophication is linked to high accumulation rates of organic matter, an increased presence of bacteria in sediment microfacies, and a decrease in the Fe/Mn ratio in the sediment. In addition, a change in varve type from calcite- to aragonite-dominated in 1983 and a higher Sr concentration during the 1990s indicate an increasingly saline aquatic environment. Comparison with meteorological data suggests that lower precipitation during a persistent positive North Atlantic Oscillation mode along with a gradual increase in mean summer temperature since the 1980s may have enhanced the saline conditions. These findings demonstrate that climate change can intensify the human impact on aquatic ecosystems. In conclusion, our analytical approach provides a valuable tool for evaluating the degree of degradation of Etoliko lagoon and the effectiveness of implemented management plans on the aquatic ecosystem, indicating that the efforts to restore its water circulation have only weakly contributed towards an environmental recovery

Combined hydrological, rainfall–runoff, hydraulic and sediment transport modeling in Upper Acheloos River catchment

Summarization: The downstream impact of dams may solve but may also cause problems in catchment management. The present study assesses the hydrodynamic and sand transport regime of Acheloos River, focusing in the area upstream of the Kremasta Dam. Calibration and validation of water discharge presented very satisfactory coefficients of efficiency (Nash–Sutcliffe up to 85%). The proposed and applied in this study system of models and methods may be used as a water and sediment management tool in dammed or undammed catchments. The results from the present study are deemed to contribute towards improving the existing knowledge of the Acheloos hydrodynamic regime and better comprehending the sediment transport mechanisms.Presented on: Desalination and Water Treatmen

Varved sediment record from Etoliko Lagoon

To achieve deeper understanding of climate variability during the last millennium in SE Europe, we report new sedimentological and paleoecological data from Etoliko Lagoon, Western Greece. The record represents the southernmost annually laminated (i.e., varved) archive from the Balkan Peninsula spanning the Little Ice Age, allowing insights into critical time intervals of climate instability such as during the Maunder and Dalton solar minima. After developing a continuous, ca. 500-year-long varve chronology, high-resolution µ-XRF counts, stable-isotope data measured on ostracod shells, palynological (including pollen and dinoflagellate cysts), and diatom data are used to decipher the season-specific climate and ecosystem evolution at Etoliko Lagoon since 1450 AD. Our results show that the Etoliko varve record became more sensitive to climate change from 1740 AD onwards. We attribute this shift to the enhancement of primary productivity within the lagoon, which is documented by an up to threefold increase in varve thickness. This marked change in the lagoon's ecosystem was caused by: (i) increased terrestrial input of nutrients, (ii) a closer connection to the sea and human eutrophication particularly from 1850 AD onwards, and (iii) increasing summer temperatures. Integration of our data with those of previously published paleolake sediment records, tree-ring-based precipitation reconstructions, simulations of atmospheric circulation and instrumental precipitation data suggests that wet conditions in winter prevailed during 1740-1790 AD, whereas dry winters marked the periods 1790-1830 AD (Dalton Minimum) and 1830-1930 AD, the latter being sporadically interrupted by wet winters. This variability in precipitation can be explained by shifts in the large-scale atmospheric circulation patterns over the European continent that affected the Balkan Peninsula (e.g., North Atlantic Oscillation). The transition between dry and wet phases at Etoliko points to longitudinal shifts of the precipitation pattern in the Balkan Peninsula during the Little Ice Age