Twenty-one plant leaf materials were screened for benzene adsorption efficiency in the static system, and the leaf material from Dieffenbachia picta, Acrostichum aureum, Ficus religiosa, Lagerstroemia macrocarpa, Alstonia scholaris, and Dracaena sanderiana were found to have high potential for benzene removal. The relation between quantity and composition of wax to benzene removal efficiency was studied. Although high quantities of wax occurred in some leaf materials, low benzene removal was clearly found if compared with other plant materials with the same wax quantity. Alpha-linoleic acid and dodecyl cyclohexane were found to be the main composition in plant leaf materials with high benzene adsorption, and it might be a key factor for benzene removal.

Biomonitoring of atmospheric ammonia (NH₃) concentrations is generally performed with epiphytic lichens, using species’ abundances and/or nitrogen concentration as monitoring tools. However, the potential of leaf characteristics of trees to monitor the atmospheric NH₃ concentration has remained largely unexplored. Therefore, we performed a passive biomonitoring study with common oak (Quercus robur L.) at 34 sampling locations in the near vicinity of livestock farms, located in Flanders (northern Belgium). We aimed at evaluating the potential of specific leaf area, leaf area fluctuating asymmetry, stomatal resistance, and chlorophyll content of common oak to monitor a broad range of NH₃ concentrations (four-monthly average of 1.9–29.9 μg m⁻³). No significant effects of ambient NH₃ concentration on the abovementioned leaf characteristics were revealed. Probably, differences in climate, soil characteristics, and concentrations of other air pollutants and/or genotypes confounded the influence of NH₃. Consequently, this study demonstrates the inability of using these morphological, anatomical, and physiological common oak leaf characteristics to monitor ambient NH₃ concentration.

Rewetting of agriculturally used peatlands has been proposed as a measure to stop soil subsidence, conserve peat and rehabilitate ecosystem functioning. Unintended consequences might involve nutrient release and changes in the greenhouse gas (GHG) balance towards CH₄-dominated emission. To investigate the risks and benefits of rewetting, we subjected soil columns from drained peat- and clay-covered peatlands to different water level treatments: permanently low, permanently inundated and fluctuating (first inundated, then drained). Surface water and soil pore water chemistry, soil-extractable nutrients and greenhouse gas fluxes were measured throughout the experiment. Permanent inundation released large amounts of nutrients into pore water, especially phosphorus (up to 11.7 mg P-PO₄ l⁻¹) and ammonium (4.8 mg N-NH₄ l⁻¹). Phosphorus release was larger in peat than in clay soil, presumably due to the larger pool of iron-bound phosphorus in peat. Furthermore, substantial amounts of phosphorus and potassium were exported from the soil matrix to the surface water, risking the pollution of local species-rich (semi-)aquatic ecosystems. Rewetting of both clay and peat soil reduced CO₂ emissions. CH₄ emissions increased, but, in contrast to the expectations, the fluxes were relatively low. Calculations showed that rewetting reduced net cumulative GHG emissions expressed as CO₂ equivalents.

The aim of the present study was to verify if cocaine, at environmental concentrations, influences the endocrine system of the European eel. Silver eels (a stage of the eel life cycle preparing the fish for the oceanic reproductive migration) were exposed to a nominal cocaine concentration of 20 ng/l during 30 days; at the same time, control, carrier, and postexposure recovery groups were made. The effects of cocaine were observed in (1) brain dopamine content, (2) plasma catecholamine levels (dopamine, norepinephrine, and epinephrine), (3) pituitary–adrenal axis activity [plasma adrenocorticotropic hormone (ACTH), corticosterone, cortisol, and aldosterone levels], and (4) pituitary–thyroid axis activity [plasma thyroid-stimulating hormone (TSH), triiodothyronine, and thyroxine levels]. In the treated group, brain dopamine, plasma catecholamines, cortisol, and TSH levels were higher, whereas ACTH, corticosterone, and triiodothyronine levels were lower than controls. In the postexposure recovery group, brain dopamine, plasma dopamine and epinephrine, and thyroxine levels further increased, whereas plasma norepinephrine, cortisol, and corticosterone levels were similar to treated values. Finally, ACTH and TSH were similar, whereas triiodothyronine levels were lower than controls. Aldosterone levels were unaffected by cocaine exposure. The results of the present study show that cocaine, at environmental concentrations, behaves like an endocrine disruptor changing brain dopamine and plasma catecholamine levels and the activity of pituitary–adrenal/thyroid axes. Since the endocrine system plays a key role in the metabolic and reproductive processes of the eel, our results suggest that environmental cocaine could be considered another cause for the decline in the European eel.

Bioclogging extensively exists in porous media, such as permeable reactive barrier (PRB), constructed wetland, reverse osmosis, and biofilter systems and affects efficiency of sewage treatment. In this paper, variation in biochemical and hydraulic parameters under discontinuous flow condition during the clogging process was obtained. Hydraulic conductivity (K) first decreased sharply to 34.22 % of the original value during the initial 12th day and, finally, decreased to 13.70 %. Hydrodynamic dispersion (D) went through slow increase, fast increase, fast decrease, slow increase, and ultimately decreased to 44.25 %. Porosity (n) decreased obviously, especially during the initial 12 days, and total bacterial counts in the inlet of the column had more than one order of magnitude increase. The bioclogging process can be divided into four stages: (1) severe bioclogging occurred and aerobic microorganisms reproduced rapidly in the inlet, (2) bioclogging existed in the entire sand column and the hydrodynamic dispersion increased drastically as anaerobic microorganisms generated some gas, (3) aerobic and anaerobic microorganisms reproduced and hydrodynamic dispersion decreased rapidly, and (4) microorganisms multiplied continuously and the hydraulic parameters (hydrodynamic dispersion, hydraulic conductivity, and porosity) decreased steadily. Bioclogging then transformed into steady stage. Based on analysis of experimental data, hydraulic conductivity (K) follows the rule of negative exponent relationship, porosity (n) accords with power exponent relationship, and hydrodynamic dispersion (D) is polynomial equation under bioclogging process.

The environmental impact assessment of mining sites represents nowadays a large interest topic in Romania. Historical pollution in the Rosia Montana mining area of Romania caused extensive damage to environmental media. This paper has two goals: to investigate the environmental pollution induced by mining activities in the Rosia Montana area and to quantify the environmental impacts and associated risks by means of an integrated approach. Thus, a new method was developed and applied for quantifying the impact of mining activities, taking account of the quality of environmental media in the mining area, and used as case study in the present paper. The associated risks are a function of the environmental impacts and the probability of their occurrence. The results show that the environmental impacts and quantified risks, based on quality indicators to characterize the environmental quality, are of a higher order, and thus measures for pollution remediation and control need to be considered in the investigated area. The conclusion drawn is that an integrated approach for the assessment of environmental impact and associated risks is a valuable and more objective method, and is an important tool that can be applied in the decision-making process for national authorities in the prioritization of emergency action.

Apart from the generation of fly ash, brine (hyper-saline wastewater) is also a waste material generated in South African power stations as a result of water re-use. These waste materials contain major species such as Al, Si, Na, K, Ca, Mg, Cl and SO₄. The co-disposal of fly ash and brine has been practiced by some power stations in South Africa with the aim of utilizing the fly ash to capture the salts in brine. The effect of the chemical interaction of the species contained in both fly ash and brine, when co-disposed, on the mobility of species in the fly ash–brine systems is the focus of this study. The up-flow percolation test was employed to determine the mobility of some major species in the fly ash–brine systems. The results of the analysed eluates from the up-flow percolation tests revealed that some species such as Al, Ca and Na were leached from the fly ash into the brine solution while some species such as Mg, Cl and SO₄ were removed to some extent from the brine solution during the interaction with fly ash. The pH of the up-flow percolation systems was observed to play a significant role on the mobility of major species from the fly ash–brine systems. The study showed that some major species such as Mg, Cl and SO₄ could be removed from brine solution using fly ash when certain amount of brine percolates through the ash.

In the present paper, undoped and Ni-doped TiO2 sol-gel nanopowders have been prepared in order to establish the effect of Ni dopant on both material structure and photocatalytic properties. Two dopant concentrations of the transition metal (0.5 and 2 wt%) have been tested. The influence of both Ni dopant concentration and temperature of thermal treatment on the prepared powders has been followed using X-ray diffraction (XRD) method. A proper program has been used in order to establish the complete XRD structural characterization (lattice parameters, crystrallite sizes, internal strains). X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) coupled with surface area electron diffraction (SAED) techniques have completed the structural and morphological characterization of the prepared materials. Magnetic measurements and photocatalytic activity determinations have also been performed. The correlation between the results of the mentioned methods has been accomplished, and the detailed interpretation of the relation between structure and photocatalytic activity measurements has been done. The concentration of 0.5 wt% of Ni dopant ensures a better photocatalytic activity, compared to that of 2 wt%. © 2013 Springer Science+Business Media Dordrecht.

Understanding denitrification rates in groundwater ecosystems can help predict where agricultural reactive nitrogen (N) contributes to environmental degradation. In situ groundwater denitrification rates were determined in subsoil, at the bedrock interface and in bedrock at two sites, grassland and arable, using an in situ 'push-pull' method with 15N-labelled nitrate (NO3 --N). Measured groundwater denitrification rates ranged from 1.3 to 469.5 μg N kg-1 day-1. Exceptionally high denitrification rates observed at the bedrock interface at grassland site (470 ± 152 μg N kg-1 day-1; SE, standard error) suggest that deep groundwater can serve as substantial hotspots for NO 3 --N removal. However, denitrification rates at the other locations were low and may not substantially reduce NO3 --N delivery to surface waters. Denitrification rates were negatively correlated with ambient dissolved oxygen, redox potential, k s and NO3 - (all p values, p < 0.01) and positively correlated with SO4 2- (p < 0.05). Higher mean N 2O/(N2O + N2) ratios at an arable (0.28) site than the grassland (0.10) revealed that the arable site has higher potential to indirect N2O emissions. Identification of areas with high and low denitrification and related site parameters can be a tool to manage agricultural N to safeguard the environment. © 2013 Springer Science+Business Media Dordrecht.

Many studies have shown the relationship between fire clearing and mercury contamination of aquatic ecosystems in the Brazilian Amazon. This study aimed at quantifying mercury content in long-time cultivated soils and at assessing the potential of a fire-free alternative clearing technique on mercury retention for long-time cultivated soils compared to traditional slash-and-burn. This case study included five land uses: one crop plot and one pasture plot cleared using slash-and-burn, one crop plot and one pasture plot cleared using chop-and-mulch, and one 40-year-old forest as a control. Low mercury concentrations were recorded in the surface horizon (24.83 to 49.48 ng g⁻¹, 0–5 cm depth). The long-time cultivation (repeated burnings) of these soils triggered large mercury losses in the surface horizon, highlighted by high enrichment factors from surface to deeper horizons. The predominant effect of repeated burnings before the experimental implementation did not let us to distinguish a positive effect of the chop-and-mulch clearing method on soil mercury retention for crops and pastures. Moreover, some processes related to the presence of the mulch may favor mercury retention (Hg volatilization decrease, cationic sites increase), while others may contribute to mercury losses (cationic competition and dislocation, mobilization by the dissolved organic matter).