Contemporary genetic structure and postglacial demographic history of the black scorpionfish, Scorpaena porcus, in the Mediterranean and the Black Seas.

Understanding the distribution of genetic diversity in the light of past demographic events linked with climatic shifts will help to forecast evolutionary trajectories of ecosystems within the current context of climate change. In this study, mitochondrial sequences and microsatellite loci were analysed using traditional population genetic approaches together with Bayesian dating and the more recent approximate Bayesian computation scenario testing. The genetic structure and demographic history of a commercial fish, the black scorpionfish, Scorpaena porcus, was investigated throughout the Mediterranean and Black Seas. The results suggest that the species recently underwent population expansions, in both seas, likely concomitant with the warming period following the Last Glacial Maximum, 20 000 years ago. A weak contemporaneous genetic differentiation was identified between the Black Sea and the Mediterranean Sea. However, the genetic diversity was similar for populations of the two seas, suggesting a high number of colonizers entered the Black Sea during the interglacial period and/or the presence of a refugial population in the Black Sea during the glacial period. Finally, within seas, an east/west genetic differentiation in the Adriatic seems to prevail, whereas the Black Sea does not show any structured spatial genetic pattern of its population. Overall, these results suggest that the Black Sea is not that isolated from the Mediterranean, and both seas revealed similar evolutionary patterns related to climate change and changes in sea level.

An electrochemical method for decreasing the concentration of sulfate and molybdenum ions in industrial wastewater.

An electrochemical method is proposed for decreasing the concentration of sulfate and molybdenum species in industrial wastewater. The method is based on electromigration, electroosmosis, electrolysis, and subsequent secondary processes. The treatment has been carried out in electrolytic cells with graphite electrodes and anodic and cathodic compartments separated by a special ceramic membrane. Influence of the equipment design and working conditions on the treatment effectiveness has been studied. The concentrations of sulfate and molybdenum were decreased from 2000-2200 mg/L to 900-1100 mg/L and 1.9-2.2 mg/L to 0.8-1.2 mg/L, correspondingly. The pH of the treated water was 8.0-8.5, no additional chemicals were introduced and voluminous sludge was not formed. The method proposed is environmentally friendly and seems to be economically feasible for treating wastewater with large flow.

Influence of zeolite transformation in a homoionic form on the removal of some heavy metal ions from wastewater.

Influence of zeolite-clinoptilolite transformation in a homoionic (Na) form on zeolite ability to immobilize Pb2+, Cd2+, Cu2+, Zn2+ and Ni2+ from single ion and multi-component solutions has been studied. Zeolite in Na form exhibits significantly increased ability to remove Cd2+, Cu2+, and Zn2+ from their single ion and multi-component solutions when the water hardness due to Ca2+ presence is not high. Zeolite pretreatment with NaCl leads to increased rate of heavy metal ions' immobilization, as well as to increased distribution coefficients that are indicative for more complete exchange process. Heavy metal ions are more strongly bound to zeolite pretreated with NaCl, compared to natural zeolite. Heavy metal ions immobilization is due to ion exchange adsorption, both in the case of natural and converted in Na form zeolite. Zeolite pretreatment with NaCl practically does not change zeolite selectivity sequence for the ions investigated.

Kinetics and thermodynamics of copper ions removal from wastewater by use of zeolite.

Natural Bulgarian zeolite was tested for its ability to remove Cu2+ from model wastewater. Influence of process variables was investigated. It was found that the optimum wastewater to zeolite ratio is 100:1 and the optimum pH value of water to be treated is 5.5 to 7.5. Zeolite with finer particles shows a higher uptake capacity. The simultaneous presence of Ca2+ and Mg2+ in concentrations similar to their concentrations in Bulgarian natural water does not significantly influence the uptake of Cu2+. Zeolite modification by treating it with NaCl, CH3COONa and NaOH increases its uptake ability. Copper ions are strongly immobilized by modified zeolite and secondary pollution of water caused by its contact with preloaded zeolite is very low (1.5-2.5% of Cu2+ preliminary immobilized have been released back into acidified water). Contacting with 2 mol dm(-3) NaCl can easily regenerate loaded zeolite; best results were obtained for zeolite modified with NaCl. Requirements of Bulgarian standards for industrial wastewater can be met by a one-stage process for an initial Cu2+ concentration of 10 mg dm(-3), and by a two stage process for an initial Cu2+ concentration of 50 mg dm(-3). Uptake of Cu2+ by zeolite from neutral wastewater has proved to be as effective as Cu2+ removal by precipitation of copper hydroxide. The process of Cu2+ uptake by natural zeolite is best described by the kinetic equation for adsorption. This fact, together with the correlation found between the Cu2+ uptake and the amount of Na+, Ca2+ and K+ released into solution by zeolite shows that the ion exchange sorption plays the basic role in Cu2+ uptake by natural zeolite. The value obtained for the apparent activation energy (26.112 kJ mol(-1) implies that the process can be easily carried out with a satisfactory rate. The uptake equilibrium is best described by the Langmuir adsorption isotherm, with Langmuir constants KL= 6.4 x 10(-2) dm3 mg(-1) and M = 6.74 mg g(-1). The apparent equilibrium constant found shows moderate affinity of zeolite for Cu2+. Values of deltaG degrees and deltaH degrees found show the spontaneous and endothermic nature of the process of Cu2+ uptake by natural zeolite.