High concentration of fluorine (F) in agricultural soils has got significant attention considering its impacts on human health, but little information was available about F distribution in farmland soil profiles around phosphorous chemical industry factories. In present study, farmland soil profiles and relevant medium samples were collected from farmlands around a main phosphorous chemical base in southwest China. At 0–100-cm profiles, concentrations of soil total F (Ft, 400.9–1612.0 mg kg⁻¹) and water soluble F (Fw, 3.4–26.0 mg kg⁻¹) decreased with profile depth in industrial areas. Industrial activities enhanced F concentration in soil mainly at 0–40-cm profiles. No disparity for both Ft and Fw distributions in paddy-dry land rotation field and dry land indicates short-term land utilization could not affect the F distribution in soil profiles. Correlation analysis showed soil organic matter and wind direction were important factors influencing the distribution of F in soil profiles. The shutdown of factory and government control of industrial emissions effectively decreased the ambient air F (Fa) concentrations in industrial areas. In where Fa and dustfall F concentrations were high, high soil Ft, Fw, and crop edible part F concentrations were found.

Salts used in road de-icing during winter season inhibit the growth and development of lawn grass species. The mechanism of plant tolerance/sensitivity to such treatments is still not clear. Moreover, there is a lack of fast and non-invasive tool to detect the effect of these salts on plants growth. This study was designed to understand the tolerance mechanism of Kentucky bluegrass plants on salinity, based on some biometric and physiological parameters. In this experiment, we simulated the urban conditions where salts are used intensively for roads de-icing. Germination capacity was evaluated at five salt solutions of NaCl (0, 50, 100, 150 and 200 mM), and physiological parameters were measured during the tillering phase at salinity levels of 0, 150 and 300 mM of NaCl. Seeds of Kentucky bluegrass did not germinate under salinity. During tillering phase, salinity affected length, area and dry mass of roots as well as the relative water content of plants, negatively. Moreover, it influenced the maximum chlorophyll fluorescence yield, quantum yield of photosystem II and electron transport rate at early period of stress. This allows us to recommend these parameters for early detection of soil salinity effects on Kentucky bluegrass plants. It seems to be that the tolerance of this plant towards salinity is based on retaining water content in leaves that allow more efficient functioning of photosynthetic apparatus.

In addition to geological, geochemical, and geophysical aspects, also, microbial aspects have to be taken into account when considering the final storage of high-level radioactive waste in a deep geological repository. Rock salt is a potential host rock formation for such a repository. One indigenous microorganism, that is, common in rock salt, is the halophilic archaeon Halobacterium noricense DSM15987ᵀ, which was used in our study to investigate its interactions with the trivalent actinide curium and its inactive analogue europium as a function of time and concentration. Time-resolved laser-induced fluorescence spectroscopy was applied to characterize formed species in the micromolar europium concentration range. An extended evaluation of the data with parallel factor analysis revealed the association of Eu(III) to a phosphate compound released by the cells (F₂/F₁ ratio, 2.50) and a solid phosphate species (F₂/F₁ ratio, 1.80). The association with an aqueous phosphate species and a solid phosphate species was proven with site-selective TRLFS. Experiments with Cm(III) in the nanomolar concentration range showed a time- and pCH₊-dependent species distribution. These species were characterized by red-shifted emission maxima, 600–602 nm, in comparison to the free Cm(III) aqueous ion, 593.8 nm. After 24 h, 40% of the luminescence intensity was measured on the cells corresponding to 0.18 μg Cm(III)/gDBM. Our results demonstrate that Halobacterium noricense DSM15987ᵀ interacts with Eu(III) by the formation of phosphate species, whereas for Cm(III), a complexation with carboxylic functional groups was also observed.

A novel pretreatment approach combined freeze with microwave was developed to promote the release of orthophosphate from excess sludge, and the phosphorus (P) was recovered from the produced supernatant by phosphate sedimentation. Batch tests examined the effects of freezing time, pH, and microwave time on the release of phosphate (PO₄³⁻-P) of the excess sludge during the freezing-microwave pretreatment. The release amount of PO₄³⁻-P reached 276 mg/L under the conditions of the freezing time of 23 h, microwave time of 5 min, and pH of 4. The optimal conditions for phosphate precipitation were pH of 9.5, the mole ratio of Mg/P of 1.8, and stirring speed of 200 rpm. The recovery efficiency of PO₄³⁻-P reached 97.42% after the reaction of 20 min and the precipitation of 50 min. The precipitated sediment mainly consisted of amorphous calcium phosphate and magnesium ammonium phosphate (MAP) which can be used as a substitute for phosphorus minerals.

High-frequency and reliable data on cyanobacteria blooming over a long time period is crucial to identify the outbreak mechanism of blooms and to forecast future trends. However, in cloudy and rainy areas, it is difficult to retrieve useful satellite images, especially in the rainy season. To address this problem, we used data from the HJ-1/CCD (Chinese environment and disaster monitoring and forecasting satellite/charge coupled device), GF-1/WFV (Chinese high-resolution satellite/wide field of view), and Landsat-8/OLI (Operational Land Imager) satellites to generate a time series of the bloom area from 2009 to 2016 in Dianchi Lake, China. We then correlated the responses of bloom dynamics to meteorological factors. Several findings can be drawn: (1) a higher bloom frequency and a larger bloom area occurred in 2011, 2013, and 2016, compared to the other years; (2) the frequency of blooms peaked in April, August, and November each year and expanded from north to south starting in July; (3) air temperature in spring and sunshine hours in summer greatly correlated to the yearly bloom area; (4) wind speed and sunshine hours strongly affected the short-term expansion of blooms and thereafter influenced the monthly bloom scale; and (5) rainfall had a strong short-term influence on the occurrence of blooms. Cyanobacteria blooms often occurred when wind speeds were less than 2.35 ± 0.78 m/s in the dry season and 2.01 ± 0.75 m/s in the rainy season, when there were 48 to 72 h of sunshine in the dry season and 35 to 57 h of sunshine in the rainy season, and when there was more than 10 mm of daily precipitation.

Transport sector of Pakistan contributes more than one half to the national energy consumption. This sector is dominated by road transportation and mainly relies on fossil fuels. The country is going through rapid unplanned urbanization, which can lead to detrimental health and ecological consequences by intensifying road transport energy consumption. Therefore, the current study investigates the effect of urbanization on road sector energy consumption controlling for economic growth, road infrastructure, and industrialization. The autoregressive distributed lag (ARDL) approach is used to examine the long-run and short-run relationship between variables over the period 1971 to 2018. The vector error correction model (VECM) is employed to analyze the causality between variables. The results disclose a significant positive contribution of urbanization to road sector energy consumption. Further, road infrastructure, economic growth, and industrialization stimulate road transport energy consumption. Feedback effect exists between urbanization and road transport energy consumption, while economic growth Granger causes road sector energy consumption, urbanization, and road infrastructure. The findings imply that energy conservation and sustainable urbanization policies are a better choice under the current economic situation. Also, road infrastructure development in rural areas may reduce rural to urban migration.

Graphene has been considered an ideal absorbent and excellent carrier for nanoparticles. Reduced graphite oxide (rGO)–supported nanoscale zero-valent iron (nZVI@rGO) is an effective material for removing nitrate from water. nZVI@rGO nanocomposites were prepared by a liquid-phase reduction method and then applied for nitrate-nitrogen (NO₃⁻-N) removal in aqueous solution under anaerobic conditions. The experimental results showed that the stability and activity of the nZVI@rGO nanocomposites were enhanced compared with those of nZVI. The influence of the reaction conditions, including the initial concentration of NO₃⁻-N, coexisting anions, initial pH of the solution, and water temperature, on NO₃⁻-N removal was also investigated by batch experiments. In a neutral or slightly alkaline environment, 90% of NO₃⁻-N at a concentration less than 50 mg/L could be removed within 1 h, and nitrogen production was approximately 15%. The process of NO₃⁻-N removal by nZVI@rGO fits well with different reaction kinetics. In addition, magnetite was the main oxidation product. RGO-supported nZVI might become a promising filler in the permeable reactive barrier process for groundwater remediation.

With raising awareness of gaseous air pollutants and their harmful impact, adsorption is considered one of the most prominent techniques for gaseous emissions control. The usage of polyaniline as a gas adsorbent is an innovative idea. This work aims to compare the efficacy of synthesized polyaniline nanotubes (PANT) as a novel adsorbent towards inorganic gases (ammonia NH₃) and volatile organic compounds (toluene vapor). PANT was prepared via a sol-gel preparation technique. The molecular structure of prepared PANT was characterized by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The morphological structure was confirmed using transmission electron microscopy (TEM) and scanning electron microscope (SEM). The PANT adsorbent surface area was determined using Brunner Emmett Teller (BET). Dynamic behavior of simulated feed gas mixture of NH₃ and toluene in air were examined using a fixed bed adsorption arrangement. The same adsorption conditions (inlet concentration, gas mixture feed flow rate, and a fixed amount of adsorbent) were applied for both NH₃ and toluene adsorption test. The NH₃ and toluene removal efficiencies were 100% and 96% respectively. Consequently, PANT is an auspicious adsorbent that can be utilized to control the indoor and outdoor gaseous air emissions. Graphical Abstracts ᅟ

In the present study, the performance of surface flow constructed wetlands (SFCWs) added with different dosage of biochar (group A 0%, group B 10%, group C 20%; v/v) was investigated, to evaluate the effect of biochar on nitrogen removal of a constructed wetland. No significant difference was observed in NH₄⁺-N removal among three groups even during different seasons. Labile organic carbon released from biochar distinctly enhanced denitrification process, which improved NO₃⁻-N removal efficiency by 4.58% in group B and 10.33% in group C. More importantly, compared with group A, biochar addition increased plant N removal by 82.24% and 192.11% in groups B and C, respectively. This result indicated that biochar could increase the accumulation of plant net biomass. In addition, TN removal of group A was much lower at low temperature (4.9 °C). However, no obvious influence of temperature on TN removal was observed in groups B and C with biochar addition. Microbial community analysis showed that, compared with that in group A, the total relative abundance of the main denitrification bacteria (Proteobacteria, Firmicutes, and Bacteroidetes) increased by 0.81% in group B and 13.63% in group C. These results provide a reasonable strategy for improving the performance of SFCWs under cold climate.

The adsorption characteristics of C.I. basic blue 26 (BB26) from aqueous solutions onto H₃PO₄-activated carbons (ACs) produced from açai stones (Euterpe oleracea Martius) and Brazil nut shells (Bertholletia excelsa H. B. K) were investigated in a batch system. The ACs were characterized by XRD, FT-IR, N₂ adsorption at 77 K, mercury porosimetry, and acidity/basicity analysis. The pseudo-first-order, pseudo-second-order kinetic models and intraparticle diffusion model were used for the kinetic interpretations. The adsorption processes follow the pseudo-second-order kinetic model. The Boyd plots revealed that the adsorption processes were mainly controlled by film diffusion. Equilibrium data were analyzed by the Langmuir and Freundlich models, at different temperatures. The equilibrium data were best represented by the Langmuir isotherm. The adsorption processes were found to be favorable, exothermic, and spontaneous. The açai stones and Brazil nut shells-based ACs were shown to be effective adsorbents for removal of BB26 from aqueous solutions.