In the present research, the potential of two biochars produced by the thermal decomposition of wheat straw (BCS) and wicker (BCW) for Cr(VI) ions removing from wastewater was investigated. The pH and the presence of chlorides and nitrates were also investigated. The Freundlich and Langmuir models were applied for the characterization of adsorption isotherms. The Langmuir model has better fitting of adsorption isotherms than the Freundlich model. The sorption process can be described by the pseudo second-order equation. The optimal adsorption capacities were obtained at pH 2 and were 24.6 and 23.6 mg/g for BCS and BCW, respectively. X-ray photoelectron spectroscopy (XPS) studies confirmed that Cr(III) ions were the most abundant chromium species on the biochars’ surface. The results indicated that the sorption mechanism of Cr(VI) on biochar involves anionic and cationic adsorption combined with Cr(VI) species reduction.

Cadmium (Cd) toxicity is a widespread problem in crops grown on contaminated soils, and little information is available on the role of inorganic amendments in Cd immobilization, uptake, and tolerance in crops especially under filed conditions. The effect of three amendments, monoammonium phosphate (MAP), gypsum, and elemental sulfur (S), on Cd immobilization in soil and uptake in wheat and rice plants, under rotation, were investigated under field conditions receiving raw city effluent since >20 years and contaminated with Cd. Three levels of each treatment, 0.2, 0.4, and 0.8 % by weight, were applied at the start of the experiment, and wheat was sown in the field. After wheat harvesting, rice was sown in the same field without application of amendments. Both crops were harvested at physiological maturity, and data regarding grain yield, straw biomass, Cd concentrations, and uptake in grain and straw, and bioavailable Cd in soil and soil pH were recorded. Both MAP and gypsum application increased grain yield and biomass of wheat and rice, while S application did not increase the yield of both crops. MAP and gypsum amendments decreased gain and straw Cd concentrations and uptake in both crops, while S application increased Cd concentrations in these parts which were correlated with soil bioavailable Cd. We conclude that MAP and gypsum amendments could be used to decrease Cd uptake by plants receiving raw city effluents, and gypsum might be a better amendment for in situ immobilization of Cd due to its low cost and frequent availability.

This paper is a contribution for validating a standard method for trace element monitoring based on transplants and analysis of aquatic bryophytes, in the framework of the EC Directive 2000/60. It presents the results of an experiment carried out to assess significant differences in the amount and variability of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in three moss species (Cinclidotus aquaticus, Fontinalis antipyretica, Platyhypnidium riparioides) and two different parts of the moss (whole plant vs apical tips). Mosses were caged in bags made of a plastic net and transplanted for 2 weeks to an irrigation canal impacted by a waste water treatment plant. Trace element concentrations were measured by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) before and after exposure to the experimental and control sites in five samples. Enrichment factors >>2 were found for Cu, Ni, Mn, Pb and Zn in all moss species, lower in C. aquaticus, intermediate in F. antipyretica and higher in P. riparioides (the species we recommend to use). The analysis of apical tips after exposure instead of the whole plant led to (I) lower concentrations of As, Co, Cr, Fe and Zn in C. aquaticus (−7 to −30 %) and of Fe and Pb (−13, −18 %) in P. riparioides, (II) higher concentrations of Cu, Ni and Zn (+14 to +18 %) in P. riparioides, while (III) no significant difference (p > 0.05) in F. antipyretica. Data variability after exposure was generally lower in apical tips, especially in C. aquaticus and in F. antipyretica, less in P. riparioides. In the aim of standardizing the moss-bag technique, the analysis of apical tips is recommended.

Rare earth elements (REE) have been recognised as critical raw materials, crucial for many clean technologies. As the gap between their global demand and supply increases, the search for their alternative resources becomes more and more important, especially for the countries which depend highly on their import. Coal fly ash (CFA), which when not utilised is considered waste, has been regarded as the possible source of many elements, including REE. Due to the increase in the energy demand, CFA production is expected to grow, making research into the use of this material a necessity. As Poland is the second biggest coal consumer in the European Union, the authors have studied different coal fly ashes from ten Polish power plants for their rare earth element content. All the fly ashes have a broadly similar distribution of rear earth elements, with light REE being dominant. Most of the samples have REE content relatively high and according to Seredin and Dai (Int J Coal Geol 94: 67–93, 2012) classification can be considered promising REE raw materials.

This study investigates the influence of Internet retailing on carbon dioxide (CO₂) emission in 77 countries categorized into developed and developing countries during the period of 2000–2013. To realize the aims of the study, a model that represents pollution is established utilizing the panel two-stage least square (TSLS) and the generalized method of moments (GMM). The results for both regressions similarly indicated that GDP growth, electricity consumption, urbanization, and trade openness are the main factors that increase CO₂ emission in the investigated countries. Although the results show that Internet retailing reduces CO₂ emission in general, a disaggregation occurs between developed and developing countries whereby Internet retailing has a significant negative effect on CO₂ emission in the developed countries while it has no significant impact on CO₂ emission in the developing countries. From the outcome of this study, a number of policy implications are provided for the investigated countries.

The pollution of the surface water in the Xiangjiang watershed in China has received much attention, whereas the groundwater conditions in the area have long been ignored. This study investigates the occurrence of Fe and Mn in the groundwater of Chengxi Town located at the terminal of the Xiangjiang River. The study area was monitored for an entire year. Thereafter, the associated health risks were identified. Results showed that approximately 81 and 73 % of the measured samples exceeded the limits for Fe and Mn in Chinese drinking water, respectively. pH level was found to be negatively correlated with the concentrations of Fe and Mn in the groundwater in the study area. The occurrence of Fe in the groundwater showed significant seasonal fluctuations and was possibly affected by the change in environment conditions within the aquifer. By contrast, Mn remained relatively stable in most of the area during the whole year. Overall, no health threats for adults and children in the study area were determined according to the low health index values. Nevertheless, research attention and the implementation of relevant measures are needed for certain villages with exceptionally high Mn concentrations in the groundwater.

Warning and monitoring projects of harmful algal blooms require simple and rapid methods for simultaneous and accurate detection and identification of causative algae present in the environmental samples. Here, reverse dot blot hybridization (RDBH) was employed to simultaneously detect several harmful algae by using five representative bloom-forming microalgae along the Chinese coast. A set of specific probes for RDBH were developed by PCR, cloning, and sequencing of the internal transcribed spacer (ITS), alignment analysis, and probe design. Each probe was oligo (dT)-tailed and spotted onto positively charged nylon membrane to make up a low-density oligonucleotide array. Universal primers designed within the conserved regions were used to amplify the ITS sequences by using genomic DNA of target as templates. The digoxigenin (Dig)-labeled PCR products were denatured and then hybridized to the oligonucleotide array. The array produced a unique hybridization pattern for each target species differentiating them from each other. The preparations of oligonucleotide array and hybridization conditions were optimized. The developed RDBH demonstrated a detection limit up to 10 cells. The detection performance of RDBH was relatively stable and not affected by non-target species and the fixation time of target species over at least 30 days. The RDBH could recover all the target species from the simulated field samples and target species confirmed by the subsequent microscopy examination in the environmental samples. These results indicate that RDBH can be a new technical platform for parallel discrimination of harmful algae and is promising for environmental monitoring of these microorganisms.

To better understand the potential impacts of metal oxide nanoparticles (NPs) on Gram(+) Bacillus subtilis and Gram(−) Escherichia coli (K12) bacteria, eight different nanosized titanium dioxide (TiO₂) suspensions with five different concentrations were used. Water quality parameters (pH, temperature, and ionic strength), light sources, and light intensities were also changed to achieve different environmental conditions. The photosensitive TiO₂ NPs were found to be harmful to varying degrees under ambient conditions, with antibacterial activity increasing with primary particle sizes from 16 to 20 nm. The presence of light was a significant factor under most conditions tested, presumably due to its role in promoting generation of reactive oxygen species (ROS). However, bacterial growth inhibition was also observed under dark conditions and different water quality parameters, indicating that undetermined mechanisms additional to photocatalytic ROS production were responsible for toxicity. The results also indicated that nano-TiO₂ particles in the absence and the presence of photoactivation induced lipid peroxidation and cellular respiration disruption.

Aerobic denitrification is the main process for high N₂O production in acid tea field soil. However, the biological mechanisms for the high emission are not fully understood. In this study, we examined N₂O emission and denitrifier communities in 100-year-old tea soils with four pH levels (3.71, 5.11, 6.19, and 7.41) and four nitrate concentration (0, 50, 200, and 1000 mg kg⁻¹of NO₃⁻-N) addition. Results showed the highest N₂O emission (10.1 mg kg⁻¹over 21 days) from the soil at pH 3.71 with 1000 mg kg⁻¹NO₃⁻addition. The N₂O reduction and denitrification enzyme activity in the acid soils (pH <7.0) were significantly higher than that of soils at pH 7.41. Moreover, TRF 78 of nirS and TRF 187 of nosZ dominated in soils of pH 3.71, suggesting an important role of acidophilic denitrifiers in N₂O production and reduction. CCA analysis also showed a negative correlation between the dominant denitrifier ecotypes (nirS TRF 78, nosZ TRF 187) and soil pH. The representative sequences were identical to those of cultivated denitrifiers from acidic soils via phylogenetic tree analysis. Our results showed that the acidophilic denitrifier adaptation to the acid environment results in high N₂O emission in this highly acidic tea soil.

Ecophysiological and antioxidant traits were evaluated in sage (Salvia officinalis) plants exposed to 120 ppb of ozone for 90 consecutive days (5 h day⁻¹). At the end of fumigation, plants showed slight leaf yellowing that could be considered the first visual symptom of leaf senescence. Ozone-stressed leaves showed (1) reduced photosynthetic activity (−70 % at the end of exposure), (2) chlorophyll loss (−59 and −56 % of chlorophyll a and b concentrations, starting from 30 days from the beginning of exposure), and (3) cellular water deficit (−12 % of the relative water content at the end of the fumigation). These phenomena are indicative of oxidative stress in the chloroplasts (as confirmed by the strong degradation of β-carotene) despite the photoprotection conferred by xanthophyll cycle [as demonstrated by the significant rise of de-epoxidation index, reaching the maximum value at the end of the treatment (+69 %)], antioxidant compounds [as confirmed by the increase of phenols (in particular caffeic acid and rosmarinic acid)], and water-soluble carbohydrates (especially monosaccharides). By means of combined ecophysiological and biochemical approaches, this study demonstrates that S. officinalis is able to activate an adaptive survival mechanism allowing the plant to complete its life cycle even under oxidative stressful conditions.