Functionalized ordered mesoporous carbon (MOMC-NP) was synthesized by chemical modification using HNO₃ and H₃PO₄ to enhance Pb(II) adsorption. The phosphate functional group represented by P-O-C bonding onto the surface of OMC was verified by FT-IR and XPS. Batch adsorption experiments revealed the improvement of adsorption capacity by 39 times over the virgin OMC. Moreover, the Pb(II) adsorption results provided excellent fits to Langmuir model and pseudo-second-order kinetic model. The adsorption mechanism of Pb(II) onto MOMC-NP revealed the formation of metal complexes with carboxyl, hydroxyl, and phosphate groups through ion exchange reactions and hydrogen bondings. The calculated activation energy was 22.09 kJ/mol, suggesting that Pb(II) adsorption was a chemisorption. At pH>pHₚzc, the main Pb(II) existing species of Pb(II) and Pb(OH)⁺ combine with the carboxyl, hydroxyl, and phosphate functional groups via electrostatic interactions and hydrogen bonding. All these findings demonstrated that MOMC-NP could be a useful and potential adsorbent for adsorptive removal of Pb(II). Graphical abstract

The purpose of this research was to use pyrrhotite ash, a residue from the phosphate industry, as an adsorbent material for the removal of reactive red 141 (RR141) dye from aqueous solution. The collected pyrrhotite ash was characterized by X-ray diffraction (XRD), scanning electron microscopy combined with energy-dispersive X-ray analysis (SEM-EDAX), Fourier transform-infrared spectroscopy (FTIR), and pHₚzc. In batch assays, diverse operating parameters impacting the dye removal were scrutinized such as pH, contact time, initial RR141 concentration, temperature, and pyrrhotite ash dose. The equilibrium of adsorption was obtained after 60 min contact time, and 97% of RR141 dye was adsorbed at ambient temperature. The isotherm of Langmuir and the pseudo-second-order kinetic model yield a suitable fit for the obtained batch experimental data; thermodynamic parameter analysis reveals the spontaneous, exothermic aspect of adsorption. Fixed bed column experiments were also tested to probe the effectiveness of pyrrhotite ash for applications in continuous mode. The breakthrough curve was described by the models of Yoon–Nelson and Thomas.

To determine the role of organic matter in the attenuation of acid rock drainage (ARD), microcosm-based experiments were performed using ARD stimulated with plants and manures. Initial mineralogical, organic geochemical and microbial analyses indicated a predominance of goethite, a substantial amount of organic carbon originating from local sources, and a bacterial community comparable with those detected in a range of ARD sites worldwide. After 100 days of incubation, changes in the mineralogical, organic and microbiological composition of the ARD demonstrated that the plant additions stimulate microbes with the potential to degrade this organic matter but do not necessarily cause substantial Fe(III) reduction. Conversely, the greatest observed stimulation of Fe(III) reduction, associated with an increase in pH to near-neutral values, was observed using manure additions. These results demonstrate that the use of the optimal natural carbon source is important and can promote the metabolism of microorganisms potentially fuelling a range of geomicrobial processes, including iron and sulfate reduction.

The study aimed to evaluate the techniques of main principal components analysis (PCA) and hierarchical cluster analysis (HCA) as a criterion to monitor the removal of nitrogen forms and phosphorus in sequential upflow anaerobic sludge blanket (UASB), submerged aerated biological filters (SABF), and horizontal subsurface flow constructed wetland (HSSF-CW) treating different organic loads of swine wastewater. System was conducted in four organic loads of swine effluent. The UASB reactor did not provide satisfactory removal of nitrogen and phosphorus. In SABF, dissolved oxygen increased by more than 50 mg L⁻¹ in nitric forms between phases I and IV. The HSSF-CW removed 87.5 and 63.1% and 70 and 42 kg ha⁻¹d⁻¹ of nitrogen and phosphorus, respectively. The PCA showed the effect of salinity and nitrogen/organic load measured and nitrogen and phosphorus removal with high positive correlation (r > 0.80). Two components extracted from the 7 variables were responsible for 81.8, 66.7, and 61.6% of the original influent and effluent data from the UASB, SABF, and HSSF-CW reactors, associated by nutrient removals. There was a reduction in HCA similarity with application of the sequential biological treatment, with the formation of four clusters and the central highlight of the nitrite and nitrate in the SABF reactor. The multivariate techniques presented in this document reduce the number of analyses, maintaining the representativeness of the monitoring data for wastewater treatment. Graphical abstract

This study aimed to investigate the leaf epicuticular wax and the presence of heavy metals in leaves of Avicennia shaueriana, a halophyte found in Brazilian mangroves. We evaluated plants collected in mangroves located around Sepetiba Bay, Rio de Janeiro State. Heavy metals were analyzed by energy dispersive X-ray spectroscopy (EDS or EDX) and inductively coupled plasma optical emission spectrometry (ICP-OES). Chemical analysis of epicuticular wax was made by gas chromatography–mass spectrometry (GC-MS). We also evaluated the micromorphology of leaf surface using scanning electronic and light microscopy. The leaves from each mangrove presented alterations in wax layer. Fagarasterol (lupeol) in high quantity was the main triterpene identified in the leaf wax from plants collected in all mangroves: Coroa Grande (76.43%), Pedra de Guaratiba (38.91%), and Marambaia (62.56%). Al, Fe, Mn, and Zn were the main heavy metals detected in leaves from the three mangroves by ICP-OES. Thus, we show that that plants able to survive in the mangrove swamp can adapt to the exposure of heavy metals, accumulate them in their leaves, and be used in coastal area recovery projects as a phytoremediator.

The goal of the present paper was to elucidate if—and how—the parameters of the Brouers–Sotolongo fractal (BSf) (n,α) kinetic model (α and τC) on the one hand, and of the generalised Brouers–Sotolongo (GBS) isotherm model (a and b) on the other hand, are correlated with adsorption pH and temperature. For that purpose, adsorption of aqueous solutions of two common dyes, methylene blue (MB) and methyl orange (MO) was carried out on four activated carbons (ACs) at three temperatures (25, 35 and 50 °C) and three pH (2.5, 5 and 8). Adsorption kinetics and isotherms were measured, and the corresponding curves were best fitted with specific forms of the aforementioned models, and corresponding to equations known as BSf (1,α) kinetic and Brouers–Gaspard isotherm models. Correlations between all model parameters and adsorption conditions were found, bringing some information about the adsorbate–adsorbent interaction.

A 42-day comparative study was conducted to assess the impact of nanoselenium to other selenium sources on performance, antioxidant activity, immunity, and carcass traits in broilers. Ross 308 (n = 156) 1-day-old broiler chicks, with average initial body weight of 45.80 ± 0.35, were randomly allocated to 4 groups. The first group (G1) fed the basal diet without selenium supplementation. The second group (G2), the third group (G3), and the fourth group (G4) were supplemented with dietary selenium at the level of 0.3 mg kg⁻¹ diet in the form of sodium selenite, seleno-methionine, and nanoselenium, respectively. The results revealed significant improvement on most of the performance parameters of nanoselenium at the level of 0.3 mg kg⁻¹ diet (P < 0.05). Nanoselenium and seleno-methionine achieved the best dressing %, spleen index %, and thymus index %. Concerning to internal organ indices, none of these indices was significantly affected by any selenium sources (P < 0.05). Glutathione peroxidase (GSH-PX) activity and malondialdehyde (MDA) content were not significantly affected by different selenium sources among all experimental groups. Serum interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) showed significant (P < 0.05) decrease in nanoselenium supplemented group compared with other groups. In case of serum IL-10 level, a significant (P < 0.05) increase was reported in nanoselenium supplemented group followed by G3 then G2. There were no statistical differences in the serum alanine transaminase, aspartate transaminase, total protein, albumin concentration, serum creatinine level, and uric acid concentration levels among all experimental groups. It is concluded that nano selenium can be a useful and better source of selenium for broilers.

The Moravian-Silesian region of the Czech Republic with its capital city Ostrava is a European air pollution hot spot for airborne particulate matter (PM). Therefore, the spatiotemporal variability assessment of source contributions to aerosol particles is essential for the successful abatement strategies implementation. Positive Matrix Factorization (PMF) was applied to highly-time resolved PM₀.₁₅–₁.₁₅ chemical composition (1 h resolution) and particle number size distribution (PNSD, 14 nm – 10 μm) data measured at the suburban (Ostrava-Plesná) and urban (Ostrava-Radvanice) residential receptor sites in parallel during an intensive winter campaign. Diel patterns, meteorological variables, inorganic and organic markers, and associations between the chemical composition factors and PNSD factors were used to identify the pollution sources and their origins (local, urban agglomeration and regional). The source apportionment analysis resolved six and four PM₀.₁₅–₁.₁₅ sources in Plesná and Radvanice, respectively. In Plesná, local residential combustion sources (coal and biomass combustion) followed by regional combustion sources (residential heating, metallurgical industry) were the main contributors to PM₀.₁₅–₁.₁₅. In Radvanice, local residential combustion and the metallurgical industry were the most important PM₀.₁₅–₁.₁₅ sources. Aitken and accumulation mode particles emitted by local residential combustion sources along with common urban sources (residential heating, industry and traffic) were the main contributors to the particle number concentration (PNC) in Plesná. Additionally, accumulation mode particles from local residential combustion sources and regional pollution dominated the particle volume concentration (PVC). In Radvanice, local industrial sources were the major contributors to PNC and local coal combustion was the main contributor to PVC. The source apportionment results from the complementary datasets elucidated the relevance of highly time-resolved parallel measurements at both receptor sites given the specific meteorological conditions produced by the regional orography. These results are in agreement with our previous studies conducted at this site. Graphical abstract

The net greenhouse gas (NGHG) emissions and net greenhouse gas intensity (NGHGI) were investigated via the determination of nitrous oxide (N₂O) emission in loess soil under rainfed winter wheat monocropping system during 3 years of field study in Northwest China. Five treatments were carried out: control (N₀), conventional nitrogen (N) application (NCₒₙ), optimized N application with straw (SNOₚₜ), optimized N application with straw and 5% of dicyanodiamide (SNOₚₜ + DCD), and optimized N rate of slow release fertilizer with straw (SSRFOₚₜ). Over a 3-year period, the NGHG emissions were achieved 953, 1322, 564, and 1162 kg CO₂-eq ha⁻¹, simultaneously, and the NGHGI arrived 158, 223, 86, and 191 kg CO₂-eq t⁻¹ grain in NCₒₙ, SNOₚₜ, SNOₚₜ + DCD, and SSROₚₜ grain, respectively. Contrasted with conventional farming system, optimized farming methods reduced 32% of N fertilizer use without significant decrease in grain yield, but brought about 38% increase in N₂O emissions, up to 28% gained in soil CH₄ uptake. Thus, it was observed that the straw incorporation performs noticeable increased in N₂O emissions in the winter wheat cropping season. Among the optimized N fertilizer rates compared with the SNOₚₜ treatment, the SNOₚₜ +DCD and SSROₚₜ treatments decreased in N₂O emissions by approximately 55% and 13%, respectively. Additionally, the N₂O emission factor across over a 3-year period was 0.41 ± 0.08% derived from N fertilizer, and it was half of IPCC default values for upland corps. It is expected possibly due to low precipitation and soil moisture with the monocropping system. The 25% higher in the amount of rainfall (almost 300 mm in 2013–2014) during a cropping season underwent into 1–2-fold increase in N₂O emissions from N-fertilized plots. As the statistical differences among annual cumulative emissions coincided with that during winter wheat growing season, it can be concluded that crop growing season is a vital important period for the determination of N₂O emissions from under rainfed monocropping system.

The Loess Plateau is the largest apple cultivation region in the world. However, the role of rain-fed apple orchards as carbon sinks or sources, including the dynamic variation and influencing factors, are still unclear. In this study, the net ecosystem CO₂ exchange (NEE) was monitored by an eddy covariance (EC) system in Loess Plateau apple orchards during 2016–2017. The results demonstrated that the annual NEE was higher in 2016 (− 698.0 g C m⁻² year⁻¹) than in 2017 (− 554.0 g C m⁻² year⁻¹). Particularly, the amount of orchard CO₂ uptake was significantly greater in 2016 (− 772.0 g C m⁻²) than in 2017 (− 642.1 g C m⁻²) during the carbon sink period. This difference may be attributed to the higher NEE in 2016 compared to 2017 during the fast and slow growth periods. In addition, a higher daily NEE occurred to the higher air temperature (Tₐ), which promoted early sprouting in 2016 (− 3.91 g C m⁻² day⁻¹) compared to 2017 (− 2.86 g C m⁻² day⁻¹) during the fast growth period. The daily NEE in 2016 (− 2.59 g C m⁻² day⁻¹) was remarkably higher than that in 2017 (− 1.41 g C m⁻² day⁻¹) during the slow growth period, owing to the greater number of cloudy and rainy days and lower temperatures in 2017. Overall, the present study demonstrated the key role played by the amount of precipitation and temperature in regulating the NEE during the growth season and provided accurate quantitative information on the carbon budget in apple orchards. Graphical abstract