Revista de química analítica ambiental

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in surface sediments collected from 44 sites of the Ä°kizcetepeler Dam Lake, in Balıkesir province of Northwestern Turkey are determined. The soxhlet extraction procedures had been optimised and validated by using gas chromatography-Mass detector (GC_Mass). Recovery was in between 56-124%. Relative standard deviation was less than 1% and limit of detection changed from 0.0010 to 0.028 µg/g. The accuracy of the method was verified by analyzing National Institute of Standards and Technology, Standard Reference Material 1597 (NIST SRM 1597). The selectivity, accuracy and precision were quite adequate for the determination of PAHs in sediment samples. The sum PAH concentrations was 0.19 ± 0.07 mg/kg. The Factor Analysis (FA) and diagnostic analysis results indicated that pyrogenic and petrogenic sources are the important sources of PAHs. Further analysis showed that contributions of Factor 1 (mixed) and Factor 2 (pyrogenic) are 37.9% and 26.9% respectively. Factor 3 (explains 15.4 of the total variance), represents petrogenic (spills of oil products) source.

Volatile organic compounds (VOCs) emitted into headspace over discrete electronic components including resistors, capacitors, diodes, transistors, and transformers were identified and quantitatively determined in Part 1 of this series using gas chromatography/mass spectrometry. Vapors emissions of VOCs were characteristic of each component and headspace concentrations increased with temperature and persisted with time in most instances. Technology suitable for routine continuous monitoring of air quality based on gas chromatography/differential mobility spectrometry (GC/DMS) was evaluated with the same electronic components here, Part 2 of this series. Distinctive patterns in plots of ion peak intensity, retention time, and compensation voltage were obtained from VOCs from resistors, capacitors, and insulation from wires of a transformer held at 200°C for ten minutes. Intensity of response and analytically rich information produced by GC/DMS suggest further utility also as an air quality monitor or smart smoke alarm with electronics-dense habitats in spacecraft or offices and industrial venues.

The performances of syringyl lignin degradation by using Fenton and UV/Fenton processes were investigated in a self-designed cylindrical reactor. Many factors including pH, dosage of H2O2, concentration of Fe2+ initial concentration of syringyl lignin, reaction time and UV irradiation were optimized to reach the removal efficiency of syringyl lignin up to 87.5%. Specifically the optimum reactor time was 60 min, dosage of H2O2 was two times of its theoretical quantity and molar ratio of [Fe2+]/[H2O2] was 1:50 at pH 3. Furthermore, introducing UV-light into the Fenton system significantly improved the decomposition of syringyl lignin with the removal efficiency of 100% in first 30 min. In addition, the degradation mechanism of syringyl lignin by Fenton process was discussed in detail by using UV-visible spectroscopyand TOC analysis. It was found that syringyl lignin was oxidized by electron transfer of complex intermediates which contained high valence iron in homogeneous Fenton system.

The combined adsorption of Cr (III) ions and halides from aqueous solution using orange peels as adsorbent was modeled. Orange peels as adsorbent is resource-saving, and has environmental friendly behavior. The influence of initial pH, initial solution ion concentration, adsorbent dosage, halides and temperature on the adsorption efficiency was studied using batch equilibrium assays. Results showed that, adsorption of Cr (III) ions increases with decrease in initial pH (maximum at 2), increasing initial solution concentration, increasing peels dosage, absence of halides and decreasing temperature. Among the tested ï»¿isotherm ï»¿models, the Freundlich isotherm best modeled both adsorptions without and with presence of halides. Some thermodynamic parameters; ΔG, ΔH, A, ΔHr and ΔS were calculated from the experimental data, with the result showing that the adsorption process is feasible, spontaneous and follow physisorption mechanism. Thus, orange peel is effective in the sorption of chromium (III) ions from aqueous solution.

Three different types of natural sorbents were developed using natural siliceous material, sodium alginate, and impregnation of goethite in alginate matrix. Experiments were carried out for decontamination of uranium, thorium, americium and plutonium by using siliceous material, Calcium-Alginate (Cal-Alg) and Goethite impregnated Calcium- Alginate (Geo-Cal-Alg) respectively. These materials were tested for different conditions by varying their pH in the range of 1-8, 95-98% Am-241 and Pu-239+240 sorbed by Cal-Alg and Geo-Cal-Alg beads respectively and experimental sorption capacity as evaluated were Eu3+ as a natural analogue for Am-241 and Pu-239+240 is 12.16 mg g-1. Experimental results clearly showed that Th and U sorption capacity is 1 and 0.3 μg mg-1 (w/w) respectively in case of siliceous material. No change in various physicochemical characteristics of the potable water was observed after decontamination process.

Hydrogeochemical investigations were carried out in and around Tummalapalle uranium mining area in order to assess hydrogeochemistry and its evolution of hydrochemical facies. Forty groundwater samples were analyzed for various physicochemical parameters like pH, electrical conductivity (EC), Ca, Mg, Na, K, Cl, HCO3, CO3, SO4, and F. The saturation indexes (SI) of minerals were calculated by employing Visual MINTEQ software. From this it is confirmed that most of the water samples were saturated with respect to carbonate minerals and under saturated with respect to sulfate minerals. The result saturation index calculated by Visual MINTEQ together with Gibbs diagram and Indices of Base Exchange (IBE) findings indicate that dissolution of dolomite and calcite, evaporation and cation exchangeable can be main mechanisms responsible for the chemical composition of the ground waters in the studied area

Increased atmospheric carbon dioxide concentrations are causing greater dissolution of carbon dioxide into the estuarine water, which is the key factor behind today’s ongoing ocean acidification and subsequent compartmentation of heavy metals in the system. We conducted a long term survey on temporal variation of pH and its impact on heavy metals in the Matla estuary, situated in the central part of Indian Sundarbans. The present study indicates the key role of acidification (major driver) in the exchange of heavy metals from sediment compartment to the overlying aquatic phase. The lowering of pH favours the process of dissolution of selected heavy metals (Zn, Cu and Pb) and promotes the transference of metallic compounds from the sediment to the aquatic phase.