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

SmartHeliosity: Emotional ergonomics through coloured light

In this paper we present research activities on the interaction between light and human emotion. We describe the SmartHeliosity prototype which evaluates human emotions to provide appropriate coloured light in order to enhance emotional wellbeing within the working environment. We present technical specifications, colour concepts to provoke certain emotions and user feedback to the prototype system

The myth of Baker-Miller pink: Effects of colored light on physiology, cognition, and emotion?

Besides aesthetic aspects, color can have impact on human perception and behaviour. A special pink hue, the so called Baker-Miller pink, is assumed to induce calming effects. In this study, we evaluated pink and white lighting conditions with N = 29 subjects, through tests of attention, measurements of skin conductance and emotional state ratings. With an exposure time of 15 minutes including measurements, no color effect was found in skin conductance and attentional performance. There was also no difference in ratings of emotional valence and arousal between the two lighting conditions. Although, subjects rated Baker-Miller pink light significantly less activating than white light. A significant sex effect showed that women preferred pink light more than men. These results indicate that there are indeed differences in subjective perception of white and Baker-Miller pink light although they cannot be found in objective measures of physiological and cognitive processes

Beleuchtungssystem bei Schichtarbeit

Licht ist der wichtigste Zeitgeber für die zirkadianen Rhythmen des Menschen. Es kontrolliert diverse chronobiologische Funktionen, wie etwa den Schlaf-Wach-Rhythmus. Treten bei Nachtarbeit künstliche, phasenverschobene Lichtbedingungen auf, so kann dies zur Desynchronisation der endogenen Rhythmen führen und das Befinden negativ beeinflussen. Um abweichende visuelle und nichtvisuelle Lichtbedingungen bei Schichtarbeit zusammenzuführen, wurde in einem Produktionsbetrieb ein alternierendes Beleuchtungssystem installiert und erprobt. Der Beitrag stellt das Lichtkonzept sowie ausgewählte Projektergebnisse vor

The impact of dynamic lighting on cognitive processes

In this work, the variation of lighting parameters (illuminance and correlated colour temperature) was used as a prestimulus to investigate effects on cognitive processes. To synchronize the pre-programmed lighting scenarios with the stimulus presentation, a control unit with a short response time was implemented into a LED lighting unit with precisely controllable luminous intensity and correlated color temperature. We investigated effects of recurrent variations in illumination on performance and if the deviation from a standard illumination condition can trigger a neuronal response in the brain to path the way for the following conflict stimulus. In our experiment the Stroop condition showed a strong effect on the reaction time of the subjects whereas no significant difference in reaction time occurred between the two different lighting conditions

Pollen profile of sediment core Dethlingen, Germany

To better understand the environmental variability during the Holsteinian interglacial, we have palynologically analyzed a new core from Dethlingen, northern Germany, at a decadal resolution. Our data provide insights into the vegetation dynamics and thus also climate variability during the meso- to telocratic forest phases of the interglacial. Temperate mixed forests dominated the regional landscape throughout the Holsteinian. However, changes in the forest composition during the younger stages of the interglacial suggest a climatic transition towards milder conditions in winter. The strong presence of boreal floral elements during the older stages of the Holsteinian interglacial suggests a high seasonality. In contrast, during the younger stages the development of sub-Atlantic and Atlantic floral elements suggests increasingly warm and humid climatic conditions. Peak warming during the younger stage of the Holsteinian is marked by the maximum pollen abundances of Buxus, Abies, and Quercus. Although the vegetation dynamics suggest a general warming trend throughout the Holsteinian interglacial, abrupt as well as gradual changes in the relative abundances of temperate plants indicate considerable climatic variability. In particular, two marked declines in temperate taxa leading to the transient development of boreal and sub-temperate forests indicate short-term climatic oscillations that occurred within full interglacial conditions. The palynological signatures of these two regressive phases in vegetation development differ with regard to the expansion of pioneer trees, the abundances and rates of change of temperate taxa, and the presence of frost-sensitive taxa. These differences point to different mechanisms responsible for the individual regressive phases. Assuming a correlation of the interglacial at Dethlingen with Marine Isotope Stage (MIS) 11, our data suggest that temperate forests prevailed in northern Germany during the younger parts of MIS 11c

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

Diatoms, total organic carbon, and total nitrogen of sediment core Dethlingen, Germany

To provide insights into the long-term evolution of aquatic ecosystems without human interference, we here evaluate a decadal- to centennial-scale-resolution diatom record spanning about 12 ka of the Holsteinian interglacial (Marine Isotope Stage 11c). Using a partially varved sediment core from the Dethlingen palaeolake (northern Germany), which has previously been studied for palynological and microfacies signals, we document the co-evolution of the aquatic and surrounding terrestrial environment. The diatom record is dominated by the genera Stephanodiscus, Aulacoseira, Ulnaria and Fragilaria. Based on the diatom assemblages and physical sediment properties, the evolution of the Dethlingen palaeolake can be subdivided into three major phases. During the oldest phase (lasting ~1900 varve years), the lake was ~10-15 m deep and characterized by anoxic bottom-water conditions and a high nutrient content. The following ~5600 years exhibited water depths >20 m, maximum diatom and Pediastrum productivity, and a peak in allochtonous nutrient input. During this phase, water-column mixing became more vigorous, resulting in a breakdown of anoxia. The youngest lake phase (~4000-5000 years) was characterized by decreasing water depth, turbulent water conditions and decreased nutrient loading. Based on our palaeolimnological data, we conclude that the evolution of the Dethlingen palaeolake during the Holsteinian interglacial responded closely to (i) changes within the catchment area (as documented by vegetation and sedimentation) related to the transition from closed forests growing on nutrient-rich soils (mesocratic forest phase) to open forests developing on poor soils (oligocratic forest phase), and (ii) short-term climate variability as reflected in centennial-scale climate perturbations