Methylibium petroleiphilum PM1, which is capable of degrading of methyl tert-butyl ether (MTBE), was immobilized in calcium alginate gel beads. Various applications were explored to increase the mechanical strength of these gel beads. The introduction of 0.3 mol/L calcium chloride into the crosslinking solution, 0.002 mol/L calcium chloride into the growth medium, and 0.2% polyethyleneimine (PEI) as chemical crosslinking agent increased the stability of the Ca-alginate gel beads under the operation conditions of the bioreactor. The degradation rates of MTBE by the immobilized cells in the bioreactor system operated in batch and continuous mode , respectively, were compared. A MTBE biodegradation rate of 5.79 mg/L·h was reached for over 400 h (50 batches), and the immobilized cells in the bioreactor removed >96% MTBE during 50 days of operation. Molecular analysis of the PM1 cells revealed that microbial growth occurred predominantly as microcolonies in the outer area of the beads during the first 20 days of operation. The results of this study show that a continuous-mode, fixed-bed bioreactor reactor coupled with PM1-immobilized cells is a promising technology for remediating MTBE-contaminated groundwater.

Photocatalytic degradation of bisphenol A (2,2-bis(4-hydroxyphenyl)propane, BPA), a representative endocrine-disrupting compound, was carried out in the presence of the Ti-MCM-41 mesoporous molecular sieve in this investigation. The degradation rate was strongly dependent on those factors such as the catalyst, catalyst amount, radiation time, and pH value. The photolysis reaction was found to follow the Langmuir-Hinshelwood model. After the photocatalytic treatment, decomposition of BPA rendered five intermediates as follows: 2-methyl-2,3-dihydrobenzofuran, 4-hydroxyacetophenone, 1,1-diethoxyethane, isobutanol, and 3-methylbutanal, which could be the direct evidence supporting our proposal for the degradation mechanism.

The efficiency of UV- and VUV-based processes (UV, VUV, UV/H2O2, and VUV/H2O2) for removal of sulfamethoxazole (SMX) in Milli-Q water and sewage treatment plant (STP) effluent was investigated at 20°C. The investigated factors included initial pH, variety of inorganic anions (NO3 − and HCO3 −), and humic acid (HA). The results showed that the degradation of SMX in Milli-Q water at both two pH (5.5 and 7.0) followed the order of VUV/H2O2 > VUV > UV/H2O2 > UV. All the experimental data well fitted the pseudo-first order kinetic model and the rate constant (k) and half-life time (t 1/2) were determined accordingly. Indirect oxidation of SMX by generated .OH was the main degradation mechanism in UV/H2O2 and VUV/H2O2, while direct photolysis predominated in UV processes. The quenching tests showed that some other reactive species along with .OH radicals were responsible to the SMX degradation under VUV process. The addition of 20 mg L−1 HA significantly inhibited SMX degradation, whereas, the inhibitive effects of NO3 − and HCO3 − (0.1 mol L−1) were observed as well in all processes except in UV irradiation for NO3 −. The removal rate decreased 1.7–3.6 times when applying these processes to STP effluent due to the complex constituents, suggesting that from the application point of view the constituents of these complexes in real STP effluent should be considered carefully prior to the use of UV-based processes for SMX degradation.

Artemisia vulgaris (mugwort) is a tall (1.0–2.0 m) high biomass perennial herb which accumulates considerable amounts of metals on contaminated sites. An outdoor pot experiment was conducted on a sandy, slightly alkaline soil of moderate fertility to study the uptake of cadmium and the distribution of Cd in plant tissues of A. vulgaris. Cadmium was applied as CdCl2 (a total of 1 l solution of 0, 10, 50 and 100 mg Cd l−1) to 12-l pots with a height of 25 cm. HNO3- and water-extractable concentrations of Cd were correlated with the applied Cd at 2-cm soil depth, but were not correlated at 20-cm soil depth, suggesting that Cd was either not mobile in the soil or completely taken up by mugwort roots. The Cd concentrations in different organs of A. vulgaris and litter increased with increasing soil contamination. Leaf/soil concentration ratios (BCFs) up to 65.93 ± 32.26 were observed. Translocation of Cd to the aboveground organs was very high. The leaf/root Cd concentration ratio (translocation factor) ranged from 2.07 ± 0.56 to 2.37 ± 1.31; however, there was no correlation of translocation factors to Cd enrichment, indicating similar translocation upon different soil contamination levels. In summary, A. vulgaris is tolerant to the metal concentrations accumulated, has a high metal accumulating biomass and accumulates Cd up to about 70% in the aboveground parts. Both a high phytoextraction potential and a high value for phytostabilisation would recommend mugwort for phytoremediation.

The effects of various experimental parameters on adsorption of Zn2+ metal ion from its aqueous solution by castor seed hull and also by activated carbon have been investigated using batch adsorption experiments. It has been found that the amount of zinc adsorbed per unit mass of the hull increases with the initial metal ion concentration, contact time, solution pH and with the amount of the adsorbent. Kinetic experiments clearly indicate that adsorption of zinc on both castor hull and activated carbon is a three-step process—a rapid adsorption of the metal ion, a transition phase, and an almost flat plateau. This has also been confirmed by the intraparticle diffusion model. It has also been found that the zinc adsorption process followed pseudo-second order kinetics. The kinetic parameters including rate constants have been determined at different initial metal ion concentration, pH, amount, and type of adsorbent, respectively. The Langmuir and Freundlich adsorption isotherm models have been used to interpret the equilibrium adsorption data. The Langmuir model yields better correlation coefficients. The monolayer adsorption capacities (q m) of castor hull and activated carbon have been compared with those for others reported in the literature. The value of separation factor (R L) derived from the Langmuir model gives an indication of favorable adsorption. Finally, from comparative studies, it has been found that castor hull is a potentially attractive adsorbent as compared to commercial activated carbon for the removal of zinc from aqueus effluents.

In this work, the sorption of strontium on a Ca-bentonite (CGA) from Almería (Spain) in column experiments was studied, and the results obtained were compared with the sorption onto the Na-bentonite (MX-80). The code CTXFIT (two site non-equilibrium sorption model) was used in order to fit the experimental data and to determine sorption and transport parameters. The effect of inlet Sr(II) initial concentration and the ionic strength were evaluated. The results obtained showed that the sorption capacities as well as the transport and sorption parameters of both bentonites were affected by the initial metal concentration. In experiments with higher inlet concentrations, columns were saturated faster, leading to shorter breakthrough and exhaustion times. On the other hand, a decrease of sorption and transport parameters was observed at higher ionic strengths, which would confirm ion exchange as the main mechanism of Sr(II) sorption onto both bentonites. The sorption parameters (sorption capacity and retardation factor) obtained indicated that the Ca-bentonite from Almería (Spain) presented better sorption performance than the Na-bentonite, which was related to the physical properties of the Ca-bentonite.

The aggregate potential health impact due to ambient volatile organic compounds on the population living in the area nearby the petrochemical industrial complex in Thailand was evaluated using measured air contaminants concentration. Airborne volatile organic compounds were collected using canisters and were analyzed by gas chromatography/mass spectrophotometer following the US.EPA TO 15 procedure. Composite samples taken over a 24-h period were collected monthly. Concentrations of volatile organic compounds (VOCs) were analyzed for a suite of 24 compounds covering both carcinogenic and non-carcinogenic substances. Results were determined and analyzed in order to evaluate their spatial variability and their potential health risk. Comparison of data from each monitoring site indicated that patterns of VOCs across sites were different from their major species and their concentrations which might be influenced by nearest potential emission sources. Carcinogenic VOCs such as benzene, 1,3butadiene, and 1,2 dichloroethane were found to be higher than their annual national standards. A potential cancer risk map was drawn based on benzene concentration in order to illustrate the zone of impact and the number in the population likely to be exposed. Results indicated that 82% of the total area, and 89.6% of the total population were within the impact area. It was suspected that high concentrations of benzene and 1,3 butadiene might be attributed by both the mobile source and the point source of emissions while 1,2 dichloroethane was suspected to be emitted from factories located upwind from the monitoring sites. Hazard quotients and hazard indexes were applied to determine chronic health effects with non-cancer endpoints. Calculated values of hazard indexes for each of the target organ systems were lower than 1, which indicated that the non-cancer chronic risk due to level of volatile organic compounds in the study area was less.

In a warming climate, mercury (Hg) pathways in the Arctic can be expected to be affected. The Hg transport from the high arctic Zackenberg River Basin was assessed in 2009 in order to describe and estimate the mercury transported from land to the marine environment. A total of 95 water samples were acquired and filtered (0.4 μm pore size), and Hg concentrations were determined in both the filtered water and in the sediment. A range of other elements were also measured in the water samples. Hg concentrations in the filtered water were in general highest in the beginning of the season when the water came mainly from melted snow. THg concentrations in the sediment were in general relatively constant or slightly decreasing until mid-August, where after the concentrations increased. A principal component analysis separated the samples into spring, summer and autumn samples indicating seasonal characteristics of the patterns of element concentrations. The total amount of Hg in the sediment transported was estimated to 2.6 kg. Approximately 60% of the sediment-transported Hg occurred during a 24-h flood in the beginning of August caused by a glacial lake outburst flood. The total amount of transported dissolved Hg was estimated to 46 g, and 13% of this transport occurred during the 24-h flood. If it is assumed that the Hg transport by Zackenberg River is representative for the general glacial rivers in East Greenland, the total Hg transport into the North Atlantic from Greenland alone is approximately 4.6 tons year−1 with an estimated annual freshwater discharge of ∼440 km3.

The aim of the present study was to estimate the geochemical background and anomaly threshold values of the surface soils in Kavala, northern Greece. In order to reach this goal, a simple and practical procedure was applied. This procedure included the extraction of 42 major and trace elements by analytical grade HNO3 from 65 surface soil samples, analysis by inductively coupled plasma–optical emission spectrometry and inductively coupled plasma–mass spectrometry, the distribution of the elemental data displayed on probability graphs (Q-Q plots), and the visualization of the results spatially by GIS software. The results indicated that natural factors mostly influence the elevated concentrations of Al, Ca, Fe, K, Mg, Si, B, Ba, Ce, Ga, Ge, La, Li, Mn Rb, Sb, Se, Sn, Sr, Y, and Zr, while anthropogenic activities mostly influence the elevated concentrations of Ag, As, Cd, Co, Cr, Cs, Cu, Hg, Mo, Ni, Pb, Th, Ti, U, V, W, and Zn. Nevertheless, almost all the elements determined showed their elevated concentrations inside the industrial part of Kavala area, which implies that the anthropogenic activities taking place in the study area, influence importantly the spatial distribution of the elements. The methodology followed in this research seems to be an adequate alternative for soil environmental studies.

Coal is one of the major sources of fuel for electricity production and will continue to be used for many more decades. Thus, it is important to study the effects of disposal of coal burning byproducts including fly ash into the environment. In this study, the solubility of cations and anions from the fly ash in water is discussed. Also, the fractionation of different metals from fly ash in water is studied to understand which fraction of the metals would likely be mobilized. The results from these studies suggested that the metals in the fly ash are bound mostly to carbonate, organic, and residual fractions. Also, when water solubility data are modeled with a geochemical model (Visual MINTEQ), the saturation index predictions suggested that brucite (Mg(OH)2) and calcite (CaCO3) could potentially precipitate and mineralize the atmospheric CO2. Such mineralization process could potentially reduce the leaching of toxic metals from fly ash. Results from this study will be helpful in understanding the fate of different metals from fly ash land disposal environments.