The feasibility of using nanoscale zerovalent iron (nZVI) treatment for reducing the acute toxicity of explosive wastewater, such as 2,4,6-trinitrotoluene (TNT) red water which contains highly toxic nitroaromatic compounds (NACs), has been investigated. The water quality was evaluated before and after nZVI treatment using several different analytical techniques, including UV–Vis spectroscopy, X-ray photoelectron spectroscopy, high-performance liquid chromatography, and gas chromatography/mass spectroscopy. The acute toxicity of the wastewater was tested using a luminescence bacterium bioarray. The results indicated that the most significant toxic NACs, such as dinitrotoluene sulfonates, had been effectively removed from the TNT red water by nZVI together with the small amounts of other NACs. Following 1 h of the nZVI processing treatment, the acute toxicity of the TNT wastewater was reduced by approximately 94 %. This treatment would therefore be useful for the pretreatment of wastewaters prior to the application of a biological process. The reduction in the biotoxicity of the wastewater was based on the reductive conversion processes and adsorption behaviors of nZVI.

The effect of chronic high groundwater nitrate loading on riparian forests is poorly understood. The growth patterns of northern white cedar (Thuja occidentalis) and related plant–soil processes were examined at four riparian sites in southern Ontario, Canada which have similar vegetation, soils, and hydrology but have differed in adjacent land use for >60 years. Fertilized cropland at two riparian sites produced groundwater-fed surface flows with high mean NO3–N concentrations of 9 and 31 mg l−1, whereas mean concentrations were <0.5 mg l−1 at two control sites down slope from forest. Tree-ring analysis at the two nitrate-rich sites indicated a positive growth trend in 1980–2004 and an absence of a positive growth trend in the 1945–1970 period that preceded high rates of synthetic nitrogen fertilizer use on cropland. However, a significant increase in growth also occurred in 1980–2004 at the two control riparian sites suggesting that high groundwater nitrate inputs did not influence tree growth. Cedar foliar and litter N content did not differ significantly between the high nitrate and control sites. Litter decomposition rates measured by the litterbag technique at a nitrate-enriched and control site were similar. Litter from a high nitrate and a control site produced a similar rate of potential denitrification in lab incubations of riparian surface peat. This study indicates that prolonged nitrate inputs in groundwater did not increase nitrogen uptake and growth of white cedar or stimulate decomposition and denitrification as a result of changes in the quality of plant material. In the absence of anthropogenic nitrate inputs, riparian wetland soils are typically high in ammonium and low in nitrate, and as a consequence, white cedar may have a limited ability to utilize nitrate.

Olive oil mill wastewater (OMW) generates a wide variety of pollutants depending on the production process and other factors such as olive varieties and cultivation system. Efforts to mitigate the impact of these effluents in the environment have been made by developing more efficient treatment systems in terms of removal of chemical oxygen demand (COD), color, organic compounds, and toxicity. This study is the first that reports the potential of a treatment of OMW by biocomposites of silica–alginate–fungi (Pleurotus sajor caju and Trametes versicolor). The treatment by biocomposites can be considered as a three-step process responsible for the removal of the compounds: (1) adsorption of reactants on the monolithic structure and diffusion to the biological active sites, (2) biodegradation by the fungi, and (3) diffusion of the products resulting from the biodegradation. Both treatments tested showed potential capacity to remove organic compounds, color, COD, and toxicity. The T. versicolor biocomposites were the most effective and responsible for the reduction in color (from 38.4 to 44.9 %), COD (from 42.8 to 63.8 %), and total phenolic content (from 85.3 to 88.7 %) after 29 days of treatment. The toxicity reduction on Portuguese OMW was minimal, but the use of composites on the Moroccan OMW caused a 9.5- to 19-fold reduction in toxicity. Furthermore, the biocomposites showed potential for re-utilization for more 29 days of treatment.

Arsenic mobility around mining districts is primarily controlled by distribution and abundance of iron minerals. Arsenite-rich mine waters although frequently reported, the interaction of which with schwertmannite is poorly understood despite its high toxicity and mobility. We examined three synthetic schwertmannite types distinguished by surface area (19.9–227.5 m2/g), Fe/S molar fractions (4.7–6.6), and saturation index (−1.6–0.8) towards arsenite retention through controlled batch equilibrium studies at 22 ± 2°C and 1 atmospheric pressure in oxic conditions. Sorption isotherms were investigated as a function of dissolved arsenite concentrations (0.13–1.33 mmol/L) at constant sediment load (10 g/L) and pH (3.0) in order to understand the role of synthesis pathway and physicochemical properties on arsenite immobilization. Multilayer surface coverage with more than one process governs arsenite uptake. X-ray diffractograms, infrared spectroscopy, and high resolution electron microscopic examination revealed new phase formation where schwertmannite underwent morphological and structural degradation. Ionic exchange between schwertmannite SO 4 2− and aqueous arsenite has resulted in an elevated aqueous SO 4 2− that varied according to dissolved arsenite concentrations. Stoichiometric calculations showed that 1 mol of dissolved arsenite can effectively replace 0.12–0.19 mol of schwertmannite SO 4 2− . This study implies that schwertmannites can be used as potential adsorbents for arsenite treatment where the total uptake will be strongly controlled by both ion exchange and surface precipitation.

The photocatalytic degradation of dyes under sunlight irradiation has received much attention not only because the attempt is aimed at decomposition of pollutants but also at finding methods of making use of solar energy. Following this line, zinc oxide nano-particles were prepared using solvent thermal method in order to decompose Naphthol Green B in presence of sunlight. Complete mineralization and decolorization of Naphthol Green B were achieved in 14 h. In order to reduce the band gap of zinc oxide and increase its photocatalytic activity in sunlight, it was doped with different concentrations of aluminum (1 %, 3 %, 5 %, and 10 %). The obtained band gap energy of the Al-doped ZnO nanoparticles was investigated as a function of Al content. Reduction of band gap energy for the heavily doped ZnO nanoparticles (10 % Al) was observed from 3.29 to 3.23 eV leading to fast transfer for electron from the excited state of dye to conduction band of ZnO. Therefore, by using the 10 % Al-doped ZnO nanoparticles, the complete mineralization and decolorization of Naphthol Green B were achieved in 6 h under sunlight. These results suggested that the heavily doped ZnO nanoparticles with aluminum has a positive effect towards photocatalytic reactions with dye under solar energy.

Poultry litter leachate (PLL) is known to contain a variety of contaminants including endocrine disrupting compounds (EDCs). This study analyzed the presence of steroids and contaminants in samples of poultry litter from a broiler poultry operation in Maryland, USA. Litter samples were homogenized, hydrated, incubated for two time periods (4 and 24 h) at two temperatures (20°C and 37°C), filtered, and analyzed for steroids and anthropogenic contaminants. In addition, duplicate samples were spiked with 17‐β estradiol (E2) and testosterone (T), and β-glucuronidase and aryl sulfatase, to measure steroid recovery and the presence of conjugates, respectively. A steroid recovery rate of 71 and 73% was obtained from E2 and T spiked samples, respectively. Increased incubation duration demonstrated an increased trend in E2 and a decreased trend in androgen (T and/or dihydrotestosterone [DHT]) concentrations, regardless of temperature. In contrast, increased incubation temperature displayed different trends in E2 and androgen concentrations. High temperature with a 4-h incubation resulted in an increased trend in androgen with no effect on E2. However, after 24 h of incubation at high temperature, an increased trend in E2 was observed with no effect on androgen. The presence of de-conjugating enzymes resulted in a greatly increased trend in T concentrations with a slight increased trend of E2 concentrations. Trace amounts of several metals and anthropogenic compounds were detected. Arsenic, barium, endosulfan, and bis (2-ethylhexyl) phthalate were detected at quantifiable levels. This study demonstrates that PLL contains potential EDCs and contaminants that can be toxic to, and bioaccumulate in, aquatic fauna. Determination of EDC concentrations in environmental samples is important to elucidate potential detrimental effects of agricultural runoff on aquatic wildlife.

The formation of complexes between tebuconazole (Teb) and cadmium in simplified model solutions as well as soil solutions was studied using electrospray ionization mass spectrometry. Teb and cadmium form two types of complexes with the general formulas [Cd(Teb) ₙ ]²+ (n = 1–4) and [CdI(Teb) ₘ ]+ (m = 1–3), where iodine corresponds to the counterion used. The most intense Teb/cadmium complex is [CdI(Teb)₂]+, and the most stable one is [Cd(Teb)(Teb − H)]+. Another detected complex, the dication [Cd(Teb)₄]²+, was considered as the origin complex for the iodine-free complexes and was found in a sample prepared from forest soil solution naturally contaminated with cadmium ions.

The effect of activated sludge acclimation on the biodegradation of toluene and dimethyldisulphide (DMDS) in the presence of a non-aqueous phase liquid, polydimethylsiloxane (PDMS), in a two-phase partitioning bioreactor was characterized. The influence of the presence of PDMS, at a ratio of 25% (v/v), and acclimation of activated sludge on two hydrophobic VOC biodegradation was studied. Activated sludge were acclimated to each VOC and in the presence of the non-aqueous phase liquid, namely in the emulsion of PDMS in water. Using acclimated cells, 97.9% and 108.7% improvement of the mean biodegradation rates were recorded for toluene and DMDS, respectively, if compared to the values recorded in the absence of acclimation. While and in agreement with the lower solubility in water of DMDS if compared to toluene, a most significant effect of PDMS addition on the rate of DMDS removal was recorded, 87.0% and 153.6% for toluene and DMDS, respectively. In addition and if both biomass acclimation and PDMS addition were considered, overall improvements of the removal rates were 204% and 338% for toluene and DMDS.

Nitrogen (N) deposition to the ocean is thought to be increasing worldwide, but the amount of coastal and open ocean measurements is very limited. In this paper, we assess N deposition in the coastal zone of Cayo Coco, in central Cuba, during a multi-annual period (2005–2007). Wet and dry N depositions were estimated based on the NH 4 + and NO x – concentrations in the rain. Cold fronts and troughs, coming from the west, contributed most to rain (41%) and to N deposition, followed by tropical waves and storms coming from the east, which caused 31% of the rain. Average concentrations of NH 4 + and NO x – in the rain were 8.8 and 8.3 μM. NO x – presented a clearly decreasing trend (0.26 μM per month), decreasing by half during 2005–2007. Total N deposition averaged 3.23 kg N ha−1 year−1, similar to that found in Virgin Islands and Puerto Rico, but lower than previously measured in Cuba and in nearby areas of the USA and than model predictions for the oceanic region around Cuba. These low values and the decreasing trend found are attributed to drastic reduction of fossil fuel and fertilizer use in Cuba since 1990. Because land input has decreased even more drastically, deposition seems to be nowadays the most important N source to the coastal zone of Cayo Coco. The δ15N range of seagrass (Thalassia testudinum) and macroalgae (Penicillus dumetosus) in the area (−1.83‰ to 3.02‰ and +1.02‰ to +4.17‰, respectively) sustain that atmospheric sources (deposition and N2 fixation) comprise 70–90% of the N budget.

We investigated the influence of cadmium stress on zinc hyperaccumulation, mineral nutrient uptake, and the content of metal-binding proteins in Arabidopsis halleri. The experiments were carried out using plants subjected to long-term cadmium exposure (40 days) in the concentrations of 45 and 225 μM Cd²⁺. Inductively coupled plasma-mass spectrometry, size exclusion chromatography coupled with plasma-mass spectrometry, and laser ablation inductively coupled plasma-mass spectrometry used for ablation of polyacylamide gels were employed to assess the content of investigated elements in plants as well as to identify metal-binding proteins. We found that A. halleri is able to translocate cadmium to the aerial parts in high amounts (translocation index >1). We showed that Zn content in plants decreased significantly with the increase of cadmium content in the growth medium. Different positive and negative correlations between Cd content and mineral nutrients were evidenced by our study. We identified more than ten low-molecular-weight (<100 kDa) Cd-binding proteins in Cd-treated plants. These proteins are unlikely to be phytochelatins or metallothioneins. We hypothesize that low-molecular-weight Cd-binding proteins can be involved in cadmium resistance in A. halleri.