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In this study, the potential use of Azolla filiculoides Lam. for the bioremediative solution to polycyclic aromatic hydrocarbon (PAH) pollution due to crude oil spills in freshwater was investigated. The plants were grown in nitrogen-free Hoagland nutrient solution media containing 0.05%, 0.1%, 0.2%, 0.3%, 0.4% and 0.5% crude oil by volume for 15 days under greenhouse conditions. Relative growth rates of A. filiculoides decreased in the presence of crude oil in a concentration-dependent manner. The probable influence of A. filiculoides on the biodegradation of polycyclic aromatic hydrocarbons was measured by using synchronous UV fluorescence spectroscopy. GC-MS analysis were also carried out to elucidate the behavior of the oil in experimental and control samples. Although 1-2 rings PAHs have not been encountered in control or plant samples, the measured intensity for 3-4 ring PAHs in plant samples was remarkably lower in comparison to the control. Furthermore, these results demonstrated that the predominant efficacy of the A. filiculoides was for 3-4 ring PAHs at the range 0.05 to 0.2% crude oil concentrations. It could be concluded that the bioremediative potential of A. filiculoides for the removal of polycyclic aromatic hydrocarbons strongly depends on the amount of oil in the contaminated water resource. In other words, A. filiculoides could be used more effectively after the removal of excess crude oil in the spilled freshwater areas.

Here the effectiveness of cation selective membranes, produced for divalent mercury (Hg2+) preconcetration from aqueous bodies, is examined. To this end, the behavior of PVC-based membranes, functionalized with dithizone for mercury complexation, is examined by means of Energy Dispersive X-ray Fluorescence (EDXRF) and total reflection - X-ray absorption near-edge structure (TXRF–XANES) techniques. In our previous works, we successfully immobilized dithizone on PVC-based thin film substrates, creating novel Hg-selective membranes, and identified the optimal experimental parameters affecting mercury sorption from water samples. Nonetheless, the question remains, to what extent dithizone is responsible for mercury complexation on the membrane surface, or it just improves the membrane’s active surface area thus simply improving the adsorptive effect. Using the EDXRF technique it appears that membranes functionalized with dithizone has a much higher efficiency (by up to threefold) in preconcetrating mercury from water matrices, compared to the non-functionalized membranes. Then, the membranes were also examined by means of TXRF–XANES and it was identified that indeed mercury-dithizone complex is produced on the membrane surface, which is responsible for the much higher mercury sorption, compared to the non-functionalized membranes. Also, the XANES mercury-dithizone spectrum is presented. Given polymer membrane simple manufacturing procedure and their low cost this study works towards establishing a new method for very low concentration mercury analysis (sub-ppb levels) as well as mercury collection from aqueous bodies, provided that the membranes are produced and used in large-scale routine works.

This paper describes the adsorption of Al3+ ions from aqueous solutions, by natural clay (from Sakarya's Yenigün district) and coconut shell modified by means of acid treatment. Batch experiments were carried out to determine the effect of various factors such as initial pH (4-9), temperature (20, 40, 70 oC), initial concentration (10 to 200 mg L-1) and contact time (1-120 minute) on the adsorption process. The adsorption experiments were performed at a temperature of 20 ±2 oC), at 200 rpm agitation rate, with an adsorbent level of 1 g L-1, produced 98.95% (at pH 6) and 92.83% (at pH 7) maximum Al3+ removal efficiency for clay and coconut shell based adsorbents respectively. Furthermore, the process was found to be exothermic for clay and endothermic for coconut. XRF and XRD analyses of the clay variety used in adsorption analyses revealed it to be saponite clay, within the larger group of smectite clay minerals. The application of Langmuir revealed maximum adsorption capacity of 149.25 mg g-1 for natural clay adsorbent (NCA), and 120.482 mg g-1 for coconut shell adsorbent (CSA). Moreover, adsorption kinetics were found to be consistent with the second order kinetics (R2 > 0.95). The result shows that, natural clay and coconut shell adsorbents are effective adsorbents to remove Al3+ from aqueous solutions with good adsorption rate (>92.8%).

A 28-day bioassay with the earthworm (Dendrobaena veneta) was used to assessing the ecotoxic effect of mercury in study soils and sediments. This article deals with quality evaluation of the soils, sediments and plants (assimilation organs) from three localities, Rudňany, Krompachy, and water reservoir of Ružín, Eastern Slovakia (Europe) in consideration of their toxic effect on the environment. These areas are well - known for its mercury mining and metallurgical activities for several centuries. Within the frame of evaluation it was found that the concentrations of mercury exceeded some of the MPC (Max. Tolerable Risk) and IV (Serious Risk) values. The samples Rudňany tailing-SED (188.5mg/kg), Krompachy a-SED (69.4mg/kg), and Krompachy b-SED (93.4mg/kg) were the most polluted by mercury, which is evident according to it is the highest mortality on the earthworm (Dendrobaena veneta). The high mercury concentrations were obtained in the soils of the Rudňany-tailing-S (82.5mg/kg), Rudňany-tailing, valley-S (57.8mg/kg), and Krompachy 4KO-S (20.6mg/kg). A significant positive correlation is found between highest concentrations of mercury Rudňany-tailing SED Hg=188.5mg/kg (r=0.87) with the highest mortality of Dendrobaena veneta after 28 days bioassay.