Preparation of novel nanocomposite particles (NCPs) with high visible-light-driven photocatalytic activity and possessing recovery potential after advanced oxidation process (AOP) is much desired. In this study, pure anatase phase titania (TiO₂) nanoparticles (NPs) as well as three types of NCPs including nitrogen-doped titania (TiO₂-N), titania-coated magnetic silica (Fe₃O₄ cluster@SiO₂@TiO₂ (FST)), and a novel magnetically recoverable TiO₂ nanocomposite photocatalyst containing nitrogen element (Fe₃O₄ cluster@SiO₂@TiO₂-N (FST-N)) were successfully synthesized via a sol–gel process. The photocatalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM) with an energy-dispersive X-ray (EDX) spectroscopy analysis, X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), and vibrating sample magnetometer (VSM). The photocatalytic activity of as-prepared samples was further investigated and compared with each other by degradation of phenol, as a model for the organic pollutants, in deionized (DI) water under visible light irradiation. The TiO₂-N (55 ± 1.5 %) and FST-N (46 ± 1.5 %) samples exhibited efficient photocatalytic activity in terms of phenol degradation under visible light irradiation, while undoped samples were almost inactive under same operating conditions. Moreover, the effects of key operational parameters, the optimum sample calcination temperature, and reusability of FST-N NCPs were evaluated. Under optimum conditions (calcination temperature of 400 °C and near-neutral reaction medium), the obtained results revealed efficient degradation of phenol for FST-N NCPs under visible light irradiation (46 ± 1.5 %), high yield magnetic separation and efficient reusability of FST-N NCPs (88.88 % of its initial value) over 10 times reuse.

The presence of pharmaceutical drugs in aquatic ecosystems has been widely reported during the past years. Salicylic acid (SA) is mainly used in human medicine as an analgesic and antipyretic drug, being also active in preventing platelet aggregation. To study the ecotoxicological effects potentially elicited by SA in freshwater fish, brown trout individuals (Salmo trutta fario) were chronically exposed (28 days) to this drug, in order to evaluate the enzymatic and histological effects, in both gills and liver. A qualitative and semi-qualitative evaluation of the gills and liver was performed, and also a quantitative evaluation of various lamellar structures. Oxidative stress was quantified trough the determination of glutathione S-transferases (GSTs), glutathione reductase (GRed), total and selenium-dependent glutathione peroxidase (GPx) and Catalase (Cat) activities. Lipid peroxidative damage was also assessed by the quantification of thiobarbituric acid reactive substances (TBARS) in the liver. The here-obtained data showed the occurrence of oxidative stress, reflected by an increased activity of GPx and GRed in the liver; additionally, it was possible to observe non-specific histological changes in gills. The global significance of the entire set of results is discussed, giving emphasis to the ecological relevance of the responses.

We present here observations on diurnal and seasonal variation of mixing ratio and δ¹³C of air CO₂, from an urban station—Bangalore (BLR), India, monitored between October 2008 and December 2011. On a diurnal scale, higher mixing ratio with depleted δ¹³C of air CO₂ was found for the samples collected during early morning compared to the samples collected during late afternoon. On a seasonal scale, mixing ratio was found to be higher for dry summer months (April–May) and lower for southwest monsoon months (June–July). The maximum enrichment in δ¹³C of air CO₂ (−8.04 ± 0.02‰) was seen in October, then δ¹³C started depleting and maximum depletion (−9.31 ± 0.07‰) was observed during dry summer months. Immediately after that an increasing trend in δ¹³C was monitored coincidental with the advancement of southwest monsoon months and maximum enrichment was seen again in October. Although a similar pattern in seasonal variation was observed for the three consecutive years, the dry summer months of 2011 captured distinctly lower amplitude in both the mixing ratio and δ¹³C of air CO₂ compared to the dry summer months of 2009 and 2010. This was explained with reduced biomass burning and increased productivity associated with prominent La Nina condition. While compared with the observations from the nearest coastal and open ocean stations—Cabo de Rama (CRI) and Seychelles (SEY), BLR being located within an urban region captured higher amplitude of seasonal variation. The average δ¹³C value of the end member source CO₂ was identified based on both diurnal and seasonal scale variation. The δ¹³C value of source CO₂ (−24.9 ± 3‰) determined based on diurnal variation was found to differ drastically from the source value (−14.6 ± 0.7‰) identified based on seasonal scale variation. The source CO₂ identified based on diurnal variation incorporated both early morning and late afternoon sample; whereas, the source CO₂ identified based on seasonal variation included only afternoon samples. Thus, it is evident from the study that sampling timing is one of the important factors while characterizing the composition of end member source CO₂ for a particular station. The difference in δ¹³C value of source CO₂ obtained based on both diurnal and seasonal variation might be due to possible contribution from cement industry along with fossil fuel / biomass burning as predominant sources for the station along with differential meteorological conditions prevailed.

The increasing levels of heavy metals in the environment generally related with the rapid industrialization and urbanization. Mercury (Hg) is a global toxin with wide concerns, and China gradually becomes the main producer, consumer, and emitter of Hg in the world. However, few historical data are available on the occurrence of Hg in Chinese urban areas. Here, we collected 35 lake surface sediment samples from 35 public parks and 1 sediment core in the Luxun Park in Shanghai, a hyper-urbanization city in China, to determine the spatial and vertical distributions of total mercury (THg) and methylmercury (MeHg) and to explore the Hg pollution history with the industrial development. Higher concentrations of Hg and MeHg and greater Hg enrichment were found in urban areas compared with suburban area with the following order: central urban core area > developed urban area > developing urban area > suburban area. The THg concentration in the sediment core showed an increasing trend from 1876 to 2000 and a decreasing trend from 2000 to 2012, coinciding with the process of industrialization and urbanization in Shanghai. However, THg fluxes unceasingly increased from 1876 to present probably attributed to coal consumption in the suburban area and transportation agglomeration in the central urban core area. Unlike THg, no significant variations for MeHg with time and the maximum value (0.17 μg/kg) appeared in 1947. The methylation ratio of MeHg to THg in the sediment is pretty low, and more studies are needed to further understand the fate of Hg in the environment.

In order to assess the potential of wetland plants to remediate metals from a paper mill effluent contaminated wetland site in Northeast India, 25 abundant plant species belonging to 15 different families, soil, and water samples from the sites were tested for Pb, Zn, Mg, and Fe by atomic absorption spectrophotometer. The results showed that metal accumulation by wetland plants differed among species and tissues. Plants thrived in high Pb, Zn, Mg, and Fe which indicated their tolerance. According to the criteria used for selecting plants for phytoremediation such as high metal tolerance, short life cycle, wide distribution, large shoot biomass and translocation factor (TF) >1; five species each were Mg and Fe accumulators, nine species were Pb accumulators and, eight species were Zn accumulators and the rest were excluders. Alternanthera sessilis was the only plant species that had TF > 1 for all the four metals. The study indicated great promise for phytoremediation, as these accumulators could be used in future for practical phytoremediation approaches and reduction of the risk from harmful metals to human health.

Forty surface sediment samples from the Hunhe River in Northeast China were evaluated for contamination by polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). The results showed that decabromodiphenyl ether (BDE-209) was the predominant congener, accounting for >98 % of PBDEs in all sediment. The concentrations of BDE-209 and HBCD ranged from 3.96 to 327 ng/g dry weight and 0.05 to 25.8 ng/g dry weight, respectively, suggesting that BDE-209 was more widely applied in the study area. The mean concentrations of BDE-209 and HBCD in the downstream portion of the Hunhe River (BDE-209 148 ng/g dry weight and HBCD 3.74 ng/g dry weight) were found to be relatively higher than those in the upstream portion of the Hunhe River and the Dahuofang Reservoir, revealing an association with municipal sewage and industrial effluent received from the cities of Fushun and Shenyang. γ-HBCD was the most abundant diastereoisomer of all three analyzed HBCD isomers; however, marked elevations of α-HBCD were also found in most sediment samples. Surprisingly, the relative abundance (mean 38 %) of α-HBCD in sediment from the upstream portion of the Hunhe River was significantly higher (p < 0.006, t test) than those in Dahuofang Reservoir (mean 24 %). Moreover, the severe heavy metal contamination associated with the frequent mining activities in this region was tentatively suggested as being responsible for the increased levels of α-HBCD.

A novel dead-end mode operation for filtering anaerobic suspensions was investigated. In this mode, the filtration system automatically adjusted backwashing frequency to a preselected transmembrane pressure set-point. This paper discusses the effectiveness of the backwashing conditions on membrane fouling. Anaerobic suspensions from a conventional wastewater treatment plant digester were used as model suspensions for the trials carried out at lab-scale. Gas sparging aided backwashing significantly enhanced membrane cleaning efficiency. No effect of gas sparging on internal fouling was detected. Also, the cleaning efficiency linearly decreased with permeate flux. Nevertheless, due to a high increase in the reversible fouling, a reasonable net permeate flux (7.2–6.8 L/h m²) can be achieved when intermediate fluxes (12–16 L/h m²) were imposed and the higher transmembrane pressure set-point value (50 kPa) was applied. Both backwashing duration and flux exhibited similar influence on cake fouling removal for a given volume of permeate produced.

Biofiltration has been widely used to reduce organic matter and control the formation of disinfection by-products in drinking water. Backwashing might affect the biofilters’ performance and the attached microbiota on filter medium. In this study, the impacts of backwashing on the removal of dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and N-nitrosamine precursors by a pilot-scale biological activated carbon (BAC) filtration system were investigated. The impacts of backwashing on biomass and microbial community structure of BAC biofilm were also investigated. Phospholipid fatty acid (PLFA) analysis showed that backwashing reduced nearly half of the attached biomass on granular activated carbon (GAC) particles, followed by a recovery to the pre-backwashing biomass concentration in 2 days after backwashing. Backwashing was found to transitionally improve the removal of DOC, DON and N-nitrosamine precursors. MiSeq sequencing analysis revealed that backwashing had a strong impact on the bacterial diversity and community structure of BAC biofilm, but they could gradually recover with the operating time after backwashing. Phylum Proteobacteria was the largest bacterial group in BAC biofilm. Microorganisms from genera Bradyrhizobium, Hyphomicrobium, Microcystis and Sphingobium might contribute to the effective removal of nitrogenous organic compounds by drinking water biofilter. This work could add some new insights towards the operation of drinking water biofilters and the biological removal of organic matter.

Renewable energy sources such as biomasses can play a pivotal role to ensure security of energy supply and reduce greenhouse gases through the substitution of fossil fuels. At present, bioenergy is mainly derived from cultivated crops that mirror the environmental impacts from the intensification of agricultural systems for food production. Instead, biomass from perennial herbaceous species growing in wetland ecosystems and marginal lands has recently aroused interest as bioenergy for electricity and heat, methane and 2nd-generation bioethanol. The aim of this paper is to assess, at local scale, the energy potential of wetland vegetation growing along the minor hydrographic network of a reclamation area in Northeast Italy, by performing energy scenarios for combustion, methane and 2nd-generation ethanol. The research is based on a cross-methodology that combines survey analyses in the field with a GIS-based approach: the former consists of direct measurements and biomass sampling, the latter of spatial analyses and scaling up simulations at the minor channel network level. Results highlight that biomass from riparian zones could represent a significant source of bioenergy for combustion transformation, turning the disposal problem to cut and store in situ wetland vegetation into an opportunity to produce sustainable renewable energy at local scale.

Diesel represents a common environmental contaminant as a result of operation, storage, and transportation accidents. The bioremediation of diesel in a contaminated soil is seen as an environmentally safe approach to treat contaminated land. The effectiveness of the remediation process is usually assessed by the degradation of the total petroleum hydrocarbon (TPH) concentration, without considering ecotoxicological effects. The aim of this study was to assess the efficacy of two bioremediation strategies in terms of reduction in TPH concentration together with ecotoxicity indices and changes in the bacterial diversity assessed using PCR-denaturing gradient gel electrophoresis (DGGE). The biostimulation strategy resulted in a 90 % reduction in the TPH concentration versus 78 % reduction from the natural attenuation strategy over 12 weeks incubation in a laboratory mesocosm-containing diesel-contaminated soil. In contrast, the reduction in the ecotoxicity resulting from the natural attenuation treatment using the Microtox and earthworm toxicity assays was more than double the reduction resulting from the biostimulation treatment (45 and 20 % reduction, respectively). The biostimulated treatment involved the addition of nitrogen and phosphorus in order to stimulate the microorganisms by creating an optimal C:N:P molar ratio. An increased concentration of ammonium and phosphate was detected in the biostimulated soil compared with the naturally attenuated samples before and after the remediation process. Furthermore, through PCR-DGGE, significant changes in the bacterial community were observed as a consequence of adding the nutrients together with the diesel (biostimulation), resulting in the formation of distinctly different bacterial communities in the soil subjected to the two strategies used in this study. These findings indicate the suitability of both bioremediation approaches in treating hydrocarbon-contaminated soil, particularly biostimulation. Although biostimulation represents a commercially viable bioremediation technology for use in diesel-contaminated soils, further research is required to determine the ecotoxicological impacts of the intervention.