Elissavet Dotsika

A hydrochemical and isotopic study of thermal waters on lesbos island (Greece)

Ionic ratios (Br[sup [minus]]/Cl[sup [minus]], Na[sup +]/Cl[sup [minus]], SO[sup 2[minus]][sub 4]/Cl[sup [minus]]) of the samples taken from thermal springs sited at Argenos-Eftalou, Polichnitos-Lisvori, and near Mytilini, on Lesbos Island, are typical of marine solutions. Stable isotope contents of these waters show that they may result from mixing between meteoric and sea water. Virtually no Cl[sup [minus]] is supplied by rock leaching. Balance equations based on oxygen-18, deuterium, and Cl[sup [minus]] contents indicate that marine sources contribute approximately one-third of the water at Argenos, Polichnitos, and Lisvori, and 100% for one of the springs, Thermi, in the Mytilini area. Sulphur-34 contents of dissolved sulfates confirm the participation of marine solutions. Equilibration temperatures based on oxygen-18 contents of dissolved sulfate and water are similar to those given by the chemical geothermometers, except for Thermi spring. The validity of the [Delta][sup 18]O (SO[sup 2[minus]][sub 4] [minus]H[sub 2]O) temperature for the latter is thus questionable.

O-H-C isotope ratio determination in wine in order to be used as a fingerprint of its regional origin

Stable isotopes have been applied to determine the origin assignment and verify the geographical provenance that is considered important characteristics of wine products both for consumers and the international regulations, of wines. Stable isotope analyses of (18)O/(16)O, D/H and (13)C/(12)C ratio for the detection of origin and of adulteration in wine are discussed in this study. The δ(13)C analysis of ethanol and wines water δ(18)O underlines the importance of the photosynthetic pathway and the environmental conditions of wine. Also we discuss the main factors that are responsible for the differentiation of the oxygen isotope ratios of wine water. Data interpretation demonstrated the efficacy of δ(18)O analysis not only in the wine but also in grape berries, preferably if the determination of the δ(18)O value is employed together with the determination of the δ(2)H isotope content of wine, for the detection of the geographical origin of wine.

Alarm Photosynthesis: Calcium Oxalate Crystals as an Internal CO2 Source in Plants

A new photosynthetic path named “alarm photosynthesis” uses mesophyll calcium oxalate crystals as the CO2 source when stomata are closed, providing adaptive advantages under drought conditions. Calcium oxalate crystals are widespread among animals and plants. In land plants, crystals often reach high amounts, up to 80% of dry biomass. They are formed within specific cells, and their accumulation constitutes a normal activity rather than a pathological symptom, as occurs in animals. Despite their ubiquity, our knowledge on the formation and the possible role(s) of these crystals remains limited. We show that the mesophyll crystals of pigweed (Amaranthus hybridus) exhibit diurnal volume changes with a gradual decrease during daytime and a total recovery during the night. Moreover, stable carbon isotope composition indicated that crystals are of nonatmospheric origin. Stomatal closure (under drought conditions or exogenous application of abscisic acid) was accompanied by crystal decomposition and by increased activity of oxalate oxidase that converts oxalate into CO2. Similar results were also observed under drought stress in Dianthus chinensis, Pelargonium peltatum, and Portulacaria afra. Moreover, in A. hybridus, despite closed stomata, the leaf metabolic profiles combined with chlorophyll fluorescence measurements indicated active photosynthetic metabolism. In combination, calcium oxalate crystals in leaves can act as a biochemical reservoir that collects nonatmospheric carbon, mainly during the night. During the day, crystal degradation provides subsidiary carbon for photosynthetic assimilation, especially under drought conditions. This new photosynthetic path, with the suggested name “alarm photosynthesis,” seems to provide a number of adaptive advantages, such as water economy, limitation of carbon losses to the atmosphere, and a lower risk of photoinhibition, roles that justify its vast presence in plants.

Study on distribution and origin of boron in groundwater in the area of Chalkidiki, Northern Greece by employing chemical and isotopic tracers

This paper presents an integrate study on the occurrence and distribution of boron in groundwater in the area of Chalkidiki, Northern Greece. Groundwater samples were collected from wells used for drinking and irrigation purposes. Samples were analysed for boron, various physicochemical parameters (T, pH, EC, Ca, Mg, Na, K, Br, Cl, HCO(3), SO(4), NO(3) and As) and isotopes ((18)O, (2)H, (11)B). Boron showed high spatial variation ranged from 0.04 to 6.5mg/L. Almost 60% of the examined wells exhibited boron concentration higher than the limit of 1mg/L proposed for water intended for human consumption. The higher concentrations were determined in geothermal waters with relatively high temperature. Correlation analysis and hierarchical cluster analysis were employed to find out possible relationships among the examined parameters and groundwater samples. Chemical and isotopic fingerprints have been used to investigate the origin of boron.

Photosynthetic capacity is negatively correlated with the concentration of leaf phenolic compounds across a range of different species

This study reveals a negative relationship between leaf phenolic compounds and photosynthetic Amax among different plant species. This indicates a functional integration among carbon gain and the concentration of leaf phenolic compounds that reflects the trade-off between growth and defence/protection demands.

A Quick and Reliable Method to Detect and Quantify Contamination from MSW Landfills: a Case Study

Geochemical characterization of two landfills, one closed and the other still active, both located near Komotini (Thrace, Greece), has been carried out. The aim was to provide an integrated and reliable methodology for a rapid assessment of the real impact of a municipal solid waste landfill, in the main environmental matrices (air and water) of the surrounding areas. The chemical (CO2, CH4, CO, H2, N2, and O2 + Ar) and isotopic characterization (δ13C(CO2) and δ13C(CH4)) of landfill gas and chemical (Na+, K+, Ca2+, Mg2+, Cl−, SO42−, HCO3−, NH4+, NO3−, NO2−, B, COD, Fe, Mn, As, Cr, Ni, Cu, Zn, Cd, Pb, and Hg) and isotopic analysis (δD, δ18O, tritium content, and δ13CDIC) of leachate, stream waters and groundwaters, and flux survey on the air–soil interface has been carried out. Combined chemical and isotopic analysis of the fluids collected inside and in the surroundings of the Komotini landfills supply a detailed picture of biogas emission and composition as well as of leachate chemistry and interaction with local waters. The results arising in this case study demonstrate that it is possible to propose a quick and reliable geochemical protocol to get a detailed picture of the state of health of the environment around a landfill.

Isotopic analysis for degradation diagnosis of calcite matrix in mortar

Mortar that was used in building as well as in conservation and restoration works of wall paintings have been analysed isotopically (δ13C and δ18O) in order to evaluate the setting environments and secondary processes, to distinguish the structural components used and to determine the exact causes that incurred the degradation phenomena. The material undergoes weathering and decay on a large proportion of its surface and in depth, due to the infiltration of water through the structural blocks. Mineralogical analysis indicated signs of sulphation and dissolution/recrystallisation processes taking place on the material, whereas stable isotopes provided information relative to the origin of the CO2 and water during calcite formation and degradation processes. Isotopic change of the initial δ13C and δ18O in carbonate matrix was caused by alteration of the primary source of CO2 and H2O in mortar over time, particularly by recrystallisation of calcite with porewater, evaporated or re-condensed water, and CO2 from various sources of atmospheric and biogenic origin. Human influence (surface treatment) and biological growth (e.g. fungus) are major exogenic processes which may alter δ18O and δ13C in lime mortar.

Chemical and Oxygen Isotopic Composition of Roman and Late Antique Glass from Northern Greece

The present paper emphasizes the importance of measuring the oxygen isotopic and chemical compositions of ancient glass, in order to constrain some features such as age, raw materials, and production technologies and to identify the “fingerprint“ of local productions. In this context, thirty-nine Roman and late Antique glass samples and eight chert samples from northern Greece were selected and analysed for their oxygen isotopic and chemical compositions. Results show that the majority of glass samples are produced using natron as flux and have 18O values of about 15.5, plus or minus a few tenths of one per mil, suggesting that raw materials probably come from Levantine area. Four samples are heavily enriched in 18O, and their chemical composition clearly shows that they were made with soda plant ash as flux. Isotopic and chemical data of Greek chert samples support the hypothesis of local production of the above samples. About half of the glass samples have chemical compositions, which allow their age to be constrained to the late Antique period. For the remaining glass, similarities with literature compositional groups are reported and discussed.

Groundwater Contamination Studies by Environmental Isotopes: A review

Water demand for urban, industrial, and agricultural purposes is a major concern in developed and third world countries. A careful evaluation for an appropriate and sustainable use of water resources is a priority. Geochemical processes can lead to measurable variations of the aquatic environment, which can be studied through the analysis of the dissolved solutes. Even if this review is not meant to be exhaustive, it is intended to give a view on the importance of environmental isotopes in the context of groundwater quality assessments. This is done by briefly recalling some basic notions for each described system, followed by relevant applications and reports about some significant case studies. This review includes well-established isotopic systematics, such as those of O and H in water, C in dissolved inorganic carbon (DIC), S and O in sulfates, and N and O in nitrates and those of boron and Sr, which in the last lustrums have found large application in the field of water geochemistry. This chapter ends with some examples related to nontraditional isotopes, i.e., Fe, Cr, and Cu, in order to highlight the potential of the environmental isotopes to trace sources, fate, and behavior of different solutes and metals in surface water and groundwater.

Clastic sedimentary features of beachrocks and their palaeo-environmental significance: comparison of past and modern coastal regimes

Clastic sedimentary features of beachrocks and unconsolidated deposits of parent beaches were investigated along the northern Aegean coastline (Greece) to assess their suitability in palaeo-environmental reconstruction. Twelve paired datasets were collected in the Thermaikos, Toroneos, Siggitikos and Ierissos gulfs of the Chalkidiki Peninsula, the adjoining Kavala Gulf and Thassos Island, comprising beachrock cores and companion beach subsurface sediments. Particle size analyses based on univariate and bivariate statistics suggest that, during the time period of beachrock formation, depositional conditions differed distinctly from those of the modern parent beaches. The results imply difference of maturity level of beach evolution from the time of cementation (coarser materials-early stage of beach formation) to modern situation (finer materials-reworked and ‘mature’ beach sediments). Furthermore, the findings indicate increasing coastal protection due to beachrock exposure in the modern swash zone. In conclusion, it is suggested that textural analysis of beachrocks in comparison with unconsolidated sediments of the parent beach might provide information regarding differences of coastal depositional regimes and future research could focus on specific-layer analysis and comparison.