Iron (Fe) nutrition status and activity of Fe-dependent enzymes is suggested to be affected by air pollution. This study was aimed to investigate changes in leaf Fe, zinc (Zn), chlorophyll (a, b), and carotenoid concentration and activity of catalase (CAT) and peroxidase (POX) in the leaves of maple (Acer negundo L.) with distance from two major sources of air pollution, i.e., Oil Refinery of Shiraz (ORS) operations and urban traffic of Imam Hossein square (AS) in Shiraz, Iran. By increasing the distance from the ORS, Fe, Zn, and chlorophyll concentration in the maple leaves increased. These changes were associated with lower intensity of chlorosis symptoms on the leaves of maple trees with distance from the ORS. Leaf activity of CAT increased with increasing distance from the ORS. Changes in concentration of carotenoids and activity of POX did not follow a distinct trend with distance from both pollution sources. No regular pattern was observed for changes in the measured parameters with distance from the urban traffic of Imam Hossein square (AS), as another major source of air pollution in the studied region. This was due to irregular changes in the concentrations of air pollutants across the sampling pathway. According to the results, significant impairment in Fe nutritional status is expected for plants exposed to the air pollution, although further studies are needed to clarify the physiological reasons of Fe chlorosis under air pollution stress.

Using ZnO nanoparticles, comparisons between sorption and sono-sorption efficiencies, equilibrium and kinetics in Direct Red 23 have been researched under the various experimental conditions. Pseudo-second-order model was practiced for the experimental data. The mechanism of the dye uptake was clarified based on the analyses of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Brunauer-Emmett-Teller (BET) surface area and total pore volume of the nanoparticles were obtained. The highest Direct Red 23 (DR23) removal efficiencies by sorption and sono-sorption processes were determined as 78.6 and 96.8 %, respectively. Experimental data have been evaluated according to Langmuir, Freundlich and Dubinin-Radushkevich. The mean energies of sorption and sono-sorption processes were calculated to be 16.22 and 25.41 kJ/mol, respectively. Arrhenius equation was used to calculate the activation energies. ΔH° and ΔG° values indicated that sorption and sono-sorption processes were endothermic processes. But, negative free energy values of ΔG° indicated that sorption and sono-sorption processes were favoured at high temperatures.

The present study aimed to minimize the environmental impact from the disposal of electrocoagulated metal hydroxide sludge (EMHS) generated during an electrocoagulation process using aluminum electrode by reusing it as an effective adsorbent for simultaneous removal of fluoride ion (F⁻) and arsenic (As) from aqueous solutions. The adsorbent was characterized by using coupled plasma optical emission spectroscopy (ICP-OES), surface areas and porosity properties, point of zero charge, and X-Ray diffractometry techniques. The surface morphology of adsorbent was studied by scanning electron microscopy (SEM). The dissolution of the adsorbent in function of pH was analyzed in batch experiments. Batch adsorption tests were employed to evaluate the removal and adsorption capacity of adsorbent, under conditions of contact time and adsorbate concentration. In order to determine maximum adsorption capacity of adsorbent and to understand the nature of reaction on their surface, the Langmuir and Freundlich isotherm were calculated. Preferable fitting of the Langmuir isotherm over Freundlich isotherm suggests monolayer coverage of adsorbate at the surface of the adsorbent. Data obtained were also applied to pseudo-first-order and pseudo-second-order equations. The rates of adsorption were found to conform to pseudo-second-order kinetics. The findings of this study revealed that the reuse of EMHS is a promising and efficient adsorbent in order to diminish the fluoride and arsenic pollution from drinking water.

Tunnel construction in watershed area of urban lakes would accelerate eutrophication by inputting nutrients into them, while mechanisms underlying the internal phosphorus cycling as affected by construction events are scarcely studied. Focusing on two main pathways of phosphorus releasing from sediment (enzymatic mineralization and anaerobic desorption), spatial and temporal variations in phosphorus fractionation, and activities of extracellular enzymes (alkaline phosphatase, β-1,4-glucosidase, leucine aminopeptidase, dehydrogenase, lipase) in sediment were examined, together with relevant parameters in interstitial and surface waters in a Chinese urban lake (Lake Donghu) where a subaqueous tunnel was constructed across it from October 2013 to July 2014. Higher alkaline phosphatase activity (APA) indicated phosphorus deficiency for phytoplankton, as illustrated by a significantly negative relationship between APA and concentration of dissolved total phosphorus (DTP). Noticeably, in the construction area, APAs in both sediment and surface water were significantly lower than those in other relevant basins, suggesting a phosphorus supply from some sources in this area. In parallel, its sediment gave the significantly lower iron-bound phosphorus (Fe(OOH)∼P) content, coupled with significantly higher ratio of iron (II) to total iron content (Fe²⁺/TFe) and dehydrogenase activities (DHA). Contrastingly, difference in the activities of sediment hydrolases was not significant between the construction area and other basins studied. Thus, in the construction area, subsidy of bioavailable phosphorus from sediment to surface water was attributable to the anaerobic desorption of Fe(OOH)∼P rather than enzymatic mineralization. Finally, there existed a significantly positive relationship between chlorophyll a concentration in surface water and Fe(OOH)∼P content in sediment. In short, construction activities within lakes may interrupt cycling patterns of phosphorus across sediment-water interface by enhancing release of redox-sensitive phosphate, and thereby facilitating phytoplankton growth in water column.

Recently observed rapid climate changes have focused the attention of researchers and river managers on the possible effects of increased flooding frequency on the mobilization and redistribution of historical pollutants within some river systems. This text summarizes regularities in the flood-related transport, channel-to-floodplain transfer, and storage and remobilization of heavy metals, which are the most persistent environmental pollutants in river systems. Metal-dispersal processes are essentially much more variable in alluvia than in soils of non-inundated areas due to the effects of flood-sediment sorting and the mixing of pollutants with grains of different origins in a catchment, resulting in changes of one to two orders of magnitude in metal content over distances of centimetres. Furthermore, metal remobilization can be more intensive in alluvia than in soils as a result of bank erosion, prolonged floodplain inundation associated with reducing conditions alternating with oxygen-driven processes of dry periods and frequent water-table fluctuations, which affect the distribution of metals at low-lying strata. Moreover, metal storage and remobilization are controlled by river channelization, but their influence depends on the period and extent of the engineering works. Generally, artificial structures such as groynes, dams or cut-off channels performed before pollution periods favour the entrapment of polluted sediments, whereas the floodplains of lined river channels that adjust to new, post-channelization hydraulic conditions become a permanent sink for fine polluted sediments, which accumulate solely during overbank flows. Metal mobilization in such floodplains takes place only by slow leaching, and their sediments, which accrete at a moderate rate, are the best archives of the catchment pollution with heavy metals.

Due to natural and production activities, mercury contamination has become one of the major environmental problems over the world. Mercury contamination is a serious threat to human health. Among the existing technologies available for mercury pollution control, the adsorption process can get excellent separation effects and has been further studied. This review is attempted to cover a wide range of adsorbents that were developed for the removal of mercury from the year 2011. Various adsorbents, including the latest adsorbents, are presented along with highlighting and discussing the key advancements on their preparation, modification technologies, and strategies. By comparing their adsorption capacities, it is evident from the literature survey that some adsorbents have shown excellent potential for the removal of mercury. However, there is still a need to develop novel, efficient adsorbents with low cost, high stability, and easy production and manufacture for practical utility.

Emissions of nitrous oxide (N₂O) from wetland ecosystems are globally significant and have recently received increased attention. However, relatively few direct studies of these emissions in response to water depth-related changes in sediment ecosystems have been conducted, despite the likely role they play as hotspots of N₂O production. We investigated depth-related differential responses of the dissolved inorganic nitrogen distribution in Phragmites australis (Cav.) Trin. ex Steud. rhizosphere versus non-rhizosphere sediments to determine if they accelerated N₂O emissions and the release of inorganic nitrogen. Changes in static water depth and P. australis growth both had the potential to disrupt the distribution of porewater dissolved NH₄⁺, NO₃⁻, and NO₂⁻ in profiles, and NO₃⁻ had strong surface aggregation tendency and decreased significantly with depth. Conversely, the highest NO₂⁻ contents were observed in deep water and the lowest in shallow water in the P. australis rhizosphere. When compared with NO₃⁻, NH₄⁺, and NO₂⁻, fluxes from the rhizosphere were more sensitive to the effects of water depth, and both fluxes increased significantly at a depth of more than 1 m. Similarly, N₂O emissions were obviously accelerated with increasing depth, although those from the rhizosphere were more readily controlled by P. australis. Pearson’s correlation analysis showed that water depth was significantly related to N₂O emission and NO₂⁻ fluxes, and N₂O emissions were also strongly dependent on NO₂⁻ fluxes (r = 0.491, p < 0.05). The results presented herein provide new insights into inorganic nitrogen biogeochemical cycles in freshwater sediment ecosystems.

Three biodegradable materials (i.e. wood chips (WC), digested sewage sludge (DSS), and lignin (LG)) obtained as by-products of industrial processes were selected for biochar (BC) production under slow pyrolysis conditions at 450 and 700 °C. At 450 °C, the analysed trace metals (Cd, Cr, Cu, Ni, Pb, and Zn) showed the same temperature trend with concentrations which varied depending on the feedstock, increasing in BCs from WC (by as much as 191 %) and DSS (by as much as 288 %) and decreasing in BC from LG (by as much as 46 %). At 700 °C, in all the BCs, the total concentration of Ni, Pb, and Zn increased (by as much as 135, 248, 283 %, respectively) and Cr decreased (by as much as 69 %) whereas the total concentration of Cd and Cu increased or decreased depending on the feedstock. The most suitable pyrolysis temperature for reducing trace metal leachability and bioavailability (450 or 700 °C) depends on the trace metal considered. The temperature of 450 °C was effective in stabilising Cr and Ni in the analysed BCs as these trace metals were not prone to leaching or present in bioavailable forms. In all the BCs, an increase in pyrolysis temperature made trace metals such as Zn and Cu more stable in the char matrix, decreasing in the bioavailable fractions, hindering leachability of Zn, and decreasing leachability of Cu to less than 1 % of the total Cu concentration. Trace metals such as Cd and Pb did not show a clear temperature trend, increasing or decreasing in the bioavailable or leachable fractions depending on the feedstock.

Fine particulate matter (PM₂.₅) is one of the major pollutants in metropolitan areas. The current study was conducted to observe the effects of PM₂.₅ on cardiac autonomic modulation. The participants included 619 men and women aged from 35–75 in a residential area in Shanghai, China. All the participants were divided into four categories according to the distance between their apartments and major road. In addition, individual PM₂.₅ was measured using SIDEPAKTM AM510 (TSI, USA) from 8:00 am to 6:00 pm. At the end of the individual PM₂.₅ measurement, the systolic pressure, diastolic pressure, heart rate (HR), low-frequency (LF), high-frequency (HF), and LF/HF were determined. The association between individual PM₂.₅ level and the above health effects was analyzed using generalized linear regression. The results showed that the average concentration of individual PM₂.₅ was 95.5 and 87.0 μg/m³ for men and women. Residential distance to major road was negatively correlated with the individual PM₂.₅. The results indicated that per 1.0 μg/m³ increase of individual PM₂.₅ was associated with a 2.3 % increase for systolic pressure, 0.3 % increase for diastolic pressure, 0.4 % decrease for LF, and 0.4 % decrease for HF. Nevertheless, there was no statistical association between individual PM₂.₅ and heart rate and LF/HF in the total model. In addition, the similar results were found in men and women excluding a significant association between PM₂.₅ and the heart rate in men. The alterations of cardiac autonomic modulation hinted that PM₂.₅ exposure might be associated with the potential occurrence of cardiovascular disease, such as arrhythmia and ischemic heart diseases.

Preparation and characterization of a novel activated carbon obtained from vine shoots by ZnCl₂ activation and its rifampicine removal capacity were investigated in this study. The effects of activation temperature and impregnation ratio (precursor/ZnCl₂) on the activated carbon properties were investigated. The prepared activated carbon was characterized by BET surface area, surface functional group analysis by Boehm’s titration and FT-IR analysis, pHₚzc, iodine number, SEM-EDX, and particle size distribution. The results showed that the surface area, pore size, and pore volume of the activated carbon increased with the increasing temperature and impregnation ratio and reached maxima at the impregnation ratio of 40/30 at 700 °C. Under the optimal conditions, it was determined that the BET surface area, total pore volume, iodine number, and pHₚzc of the activated carbon were 1689 m²/g, 0.842 cm³/g, 1276 mg/g, and 4.8, respectively, and it has mainly acidic functional groups (total 0.2516 meq/g) on its surface. The activated carbon obtained was evaluated for rifampicine removal efficiency depending on contact time, adsorbent dosage, and initial concentration of rifampicine. Maximum adsorption capacity of rifampicine by the activated carbon (Q°) was determined according to Langmuir adsorption isotherm. The adsorption data was best fitted to the Langmuir isotherm with R ² of 0.983 and Q° was found to be 476.2 mg/g.