Geochronology and petrology of recent volcanics in the eastern Aegean Sea (West Anatolia and Lesvos Island)

During the lower and middle Miocene the western Anatolia and the eastern Aegean Sea were dominated by a calcalkaline volcanism associated with minor acid and basic volcanics. The basic subcrustal volcanics consist mainly of alkali basalts and hawaiites (9.7–11.9 m.y.), nepheline hawaiites and nepheline trachyandesites (Kula area from 1.1 m.y. to the recent times). The rhyolitic volcanics (12.5 m.y.) derived by a partial melting process in the upper crust (⁸⁷Sr/⁸⁶Sr=0.7121). The calcalkaline suite (16.2–21.5 m.y., mean value⁸⁷Sr/⁸⁶Sr=0.708) shows a trend from latite-andesites to dacites and rhyodacites; a latite andesite system related to a sinking slab of lithosphere and constituted by a mixing of oceanic crust (tholeiite), oceanic sediments and/or tectonic fragments of sialic crust is envisaged.     

Rock salt mass in the Paleoproterozoic sequence of the Onega trough in Karelia (from the Onega parametric well data)

A thick (200 m) rock salt mass covering Late Archean granitoids was exposed for the first time in the Early Proterozoic volcanogenic-sedimentary formations in the Onega trough of the east Baltic Shield by the Onega parametric well. The mineral composition of salts, their geochemical features, and the isotopic composition of carbonate carbon and oxygen have been studied. After fluid inclusions present in salts, their metamorphism temperature and isotopic composition of helium and argon were determined. The obtained results give evidence of the fact that rock salts and magnesites associated with them were formed in an evaporate basin with participation of deep crustal processes. The age of the underlying granitoids (2.716 ± 9 Ma) is determined using the Pb—Pb method.     

UTCHEM model application for prediction of crude oil removal from contaminated sand columns

Soil pollution by crude oil is a challenging environmental issue for oil producing countries. Several methods have been developed for remediation of the contaminated soil including washing with different detergents. In this work, we applied UTCHEM simulator model to the sand columns polluted by 10000 and 30000 ppm of crude oil which was treated with 0.05, 0.1 and 0.2 wt% of a biological detergent, saponin. The results showed a good agreement between simulated and pilot study. The maximum remediation was 61% with a pH of 9 when we utilized 0.2 wt% saponin for the column contaminated with 30000 ppm of crude oil. 47% remediation was achieved with a pH of 9 when 0.1wt% of detergent was applied to the same column. Sensitivity analysis indicated an increase in remediation by increasing the pH with the optimum pH of 11. The best possible concentrations of surfactant solutions were 0.1 and 0.2 wt% for 10000 and 30000 ppm pollution, respectively, resulting in crude oil removal efficiencies of 69% and 72%, respectively. Simulation results also indicated that an increase in the permeability of the sand columns would also result in an increased remediation.     

Change in the circulation regime in the stratified saline Lake Shira (Siberia,Republic of Khakassia)

The in-situ data on the vertical structure and stability of the vertical stratification of saline Lake Shira over the past decade (2007–2015) are analyzed. Simplified mathematical models have shown that strong wind in the autumn of 2014 together with rather thick ice in the winter of 2015 caused a change in the circulation regime of this water reservoir from meromictic (incomplete mixing) to holomictic (compete mixing). Based on the results obtained, a circulation regime for deep saline lakes located in the continental climate zone, in particular, in the arid zones of Southern Siberia (Khakassia, Transbaikal, and Altai) can be predicted under various climate scenarios of the future.     

Glutathione S-transferase from an antarctic fish, Dissostichus mawsoni

Glutathione S-transferase activity was measured in the hepatic cytosol front Dissostichus mawsoni and Pagothenia borchgrevinki. Activity measures with 1-chloro-2,4-dinitrobenzene as substrate were 11·2 and 16·7 μmol/min/g tissue respectively. Little or no activity was detected when p-nitrobenzyl chloride or 3,4-dichloro-1-nitrobenzene were used as substrate. The hepatic glutathione S-transferases from D. mawsoni were partially purified using gel filtration and chromatofocusing. Three peaks of activity were resolved. The major isozyme (158-fold purification) eluting at pH7·1 appeared to be catalytically a homodimer. The isozyme was highly inhibited by triphenyltin chloride (IC₅₀ = 0·1 μ) while inhibition constants for Cibicron Blue 3GA, bromosulphophalein and hematin were 1·1, 20 and 34 μ respectively.     

Influence of food web structure on the biochemical composition of seston,zooplankton and recently deposited sediment in experimental freshwater mesocosms

The effects of food web structure on the quantity and biochemical composition of seston, zooplankton and recently deposited sediment in experimental freshwater mesocosms were examined. Food web structure was manipulated by addition of zooplanktivorous fish. Biochemical characterisations were carried out using lipid biomarkers (sterols, fatty acids, chlorophyll-derived compounds and long-chain alkanediols). Fish addition decreased zooplankton biomass and increased seston biomass and deposited sediment through a trophic cascade. Fish presence strongly influenced the biochemical characteristics of seston and sediment. In contrast, food web structure had a minor impact on the lipid biomarker composition of zooplankton. Although the relative abundance of sterols in the different compartments did not differ strongly between treatments, sterol profiles in seston and sediment depended on food web structure. The predominance of Δ⁷-sterols in seston and sediment in the fish treatment indicated a major contribution of Chlorophyceae. In contrast, the distribution of sterols in seston and sediment in the fishless treatment, dominated by cholesterol, indicated a major zooplanktonic input. The distribution of fatty acids and the relative abundance of chlorophyll-derived compounds and long-chain alkanediols agreed with the predominant contribution of phytoplankton or zooplankton to seston and sediment in the two treatments. The relative abundance of bacterial biomarkers suggested that the contribution of bacteria was rather low. The high relative abundance of polyunsaturated fatty acids (PUFAs) and the absence of stanols in sediments suggested low microbial reworking of organic matter in the recently accumulated sediments. The trophic cascade, generated by the addition of fish, increased the relative abundance of PUFAs in deposited organic matter, thus enhancing sediment quality and potential degradability.