The immobilized CdS/TiO₂ nanofiber (CdS/TiO₂ NF) heterostructure photocatalyst was fabricated via anodic oxidation and cyclic impregnation method. The microstructure of CdS/TiO₂ NF was characterized by SEM and TEM. The components of CdS/TiO₂ NF were identified by EDX, XPS, and Raman. The optical properties of CdS/TiO₂ NF were characterized by UV-vis DRS and PL. Results showed that CdS was loaded on the surface of TiO₂ NF in the form of particles with a diameter of about 10–80 nm. The Cd and S elements were detected on the surface of catalyst. CdS/TiO₂ NF improved the absorption performance in the ultraviolet and visible light regions and reduced the recombination of photogenerated electron-hole pairs. The performance of CdS/TiO₂ NF on degrading toluene was investigated. Results showed that the deposition of CdS enhanced the photocatalytic activity of TiO₂ NF. The toluene concentration, catalyst dosage, and flow rate had marked impact on the photocatalytic degradation efficiency of toluene. In this reaction system, the degradation ratio was 80.71% when the toluene concentration was 13 mg·L⁻¹, the photocatalyst area was 32 cm², the flow rate was 3 L·min⁻¹, and the illumination time was 100 min. The mineralization ratio after photocatalytic reaction for 100 min was about 45.02%. The immobilized CdS/TiO₂ NF photocatalyst is easy to be recycled, which can reduce the energy and material cost. This work not only highlights the intrinsical role of CdS materials in the enhanced photocatalytic performance of TiO₂ NF but also provides significant guidance on fabricating immobilized CdS/TiO₂ NF photocatalyst applied in environment remediation.

Leonardite (LND), a low-grade coal, is an inexpensive material used to improve soil fertility in humic-deficient soils. Our objective was to quantify the ability of LND to immobilize atrazine (ATZ). To accomplish this, LND morphological properties, elemental composition, and spectroscopic properties were determined. We found that LND had a high organic matter content (40.53%, w/w) with a mesopore particle structure. Fourier-transform infrared spectroscopy spectral analysis confirmed the presence of aromatic molecules, all of which contributed to ATZ adsorption. The ATZ adsorption characteristics were quantified using batch adsorption kinetic and isotherm experiments. The ATZ adsorption kinetics were best described by a pseudo-second-order kinetic model while the concentrations of ATZ adsorbed (Cₐdₛ) versus equilibrium concentrations (Cₑq) had the best fit with the Freundlich equation compared with five other isotherms tested. The ability of LND to minimize ATZ leaching was tested using one-dimensional transport experiments with packing configurations and materials. The results revealed that up to 95% of ATZ was immobilized in the LND-amended soil. The extractable ATZ residues from both soil and LND corroborated the reduction in ATZ leaching. Overall, the adsorption results indicated that LND had a high affinity for ATZ adsorption and could reduce ATZ transport to the groundwater. Graphical Abstract .

The present study aimed to remove tetracycline (TET) antibiotic molecule from an aqueous medium using adsorbents prepared from Rhizopus oryzae biomass. The TET adsorption process was discontinuous and the adsorbent biomass was crude and NaOH-sonication–modified Rhizopus oryzae fungi. Specific active surface area for crude and modified Rhizopus oryzae was 10.38 m²/g and 20.32 m²/g, respectively. The results showed that the maximum TET adsorption efficiency was determined at pH 4, temperature 25 °C, initial TET concentration 10 mg/L, contact time 80 min, and biomass quantity 2 g/L. The equilibrium behavior showed that the Langmuir model suitably described the process. The maximum TET adsorption capacity was determined to be 38.02 mg/g and 67.93 mg/g, respectively, indicating that the method of biomass modification promoted the bio-adsorption capacity. A higher correlation coefficient (R²) and lower RMSE for the pseudo-first-order kinetic than other models showed its ability to describe the behavior of TET bio-adsorption. The enthalpy thermodynamic parameter (ΔH°) for the TET adsorption process was determined − 63.847 kJ/mol and − 85.226 kJ/mol for the raw and modified Rhizopus oryzae, respectively. Therefore, it can be suggested that the biomass of Rhizopus oryzae especially the modified version can be effectively used for the TET removal from aqueous environments.

The aerosol samples of water-soluble inorganic ions (WSIs), including SO₄²⁻, NO₃⁻, NH₄⁺, Cl⁻, K⁺, Na⁺, Ca²⁺, and Mg²⁺ in size-segregated particulate matter (PM), were collected by an Anderson sampler (with 8 nominal cut-sizes ranged from 0.43 to 9.0 μm) in urban Tianjin during 2013–2014. The results showed that particulate matters in the fine mode (PM₂.₁, Dp < 2.1 μm) comprised large part of mass concentrations of aerosols, and the water-soluble ionic species in the fine mode were 47.07 ± 14.29 μg m⁻³ (spring), 67.87 ± 28.74 μg m⁻³ (summer), 86.60 ± 48.53 μg m⁻³ (autumn), and 104.16 ± 51.76 μg m⁻³ (winter), respectively, which accounted for 59.5%, 63.3%, 71.9%, and 71.4% of the PM₂.₁ mass concentrations. Secondary pollutants of SO₄²⁻, NO₃⁻, and NH₄⁺ (SNA) were the dominant contributors of WSIs, which showed a bimodal size distribution in each season, with the larger peak appeared in the size fraction of 0.65–1.1 μm and the smaller one in 3.3–5.8 μm fraction. SNA concentrations in lightly polluted days (LPD) and heavily polluted days (HPD) were observably higher than non-polluted days (NPD), especially in the fine mode, with the peak diameter moving from 0.43–0.65 μm on NPD to 0.65–1.1 μm on LPD and HPD. The correlation analysis between NH₄⁺, NO₃⁻, and SO₄²⁻ suggested that almost all SO₄²⁻ and NO₃⁻ for fine particles had been completely neutralized by NH₄⁺, and primarily existed in the forms of (NH₄)₂SO₄ and NH₄NO₃. The sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) on LPD and HPD in fine mode were observably higher than those on NPD, especially in the range of 0.65–1.1 μm and 1.1–2.1 μm. Furthermore, SOR and NOR values in the size fraction of 0.43–3.3 μm increase as the RH elevated, especially in 0.43–2.1 μm, where RH was significantly positive correlated with SOR and NOR, indicating the significant contributions of heterogeneous processes to the secondary formation of SO₄²⁻ and NO₃⁻. These results suggested an enhanced formation ability of secondary pollutants under high RH in the coast city. Therefore, controlling the precursors of SNA, such as SO₂ and NOx, would be more effective to reduce the fine particulate pollution in the coast megacity of Tianjin.

Synthesis of highly efficient photocatalysts for energy and environment catalysis is still a big challenge in the materials field. Cadmium sulfide (CdS) is a promising visible light-driven photocatalyst, which can be composited with co-catalysts to increase its photo-activity and stability. In this study, a kind of graphene material with abundant structure defects (D-rGO) is synthesized by a two-step annealing process with nitrogen-doped rGO (N-rGO) as an intermediate. The high-temperature annealing could remove the doped heteroatoms to form structure defects with five or seven carbon atoms. The D-rGO is then used as co-catalyst for the modification of CdS nanoparticles, and enhanced photocatalytic activities could be obtained. A large hydrogen evolution rate of 102.7 μmol h⁻¹ g⁻¹ is achieved, which is also effective for 4-nitrophenol reduction with a rate constant of 0.168 min⁻¹. The novel CdS/D-rGO composite contains no noble metals and could be used as multi-functional photocatalysts, thus should has great potential in the photocatalysis field.

In this work, the capacity of Trametes polyzona in degrading three textile dyes (amaranth, denim blue, and orange G) to three different concentrations (100, 150, and 200 mg/L) was evaluated. Two growth conditions were tested; in the first condition, the fungus was grown in a defined minimal medium with an initial glucose concentration of 10 g/L and adding the different concentrations of each of the dyes, and in the second condition, the same minimum medium was used but with a concentration of 3 g/L of glucose, after 7 days of fungus growth, at which time the glucose in the medium was completely consumed; each of the dyes was added at the three different concentrations. T. polyzona was able to decolorize the three dyes at the concentrations tested and a 200% increase in the decolorization rate was observed when the medium lacks glucose. Enzymatic activities of laccase, lignin peroxidase, and manganese peroxidase were detected; the enzyme laccase was the one that presented the greatest enzymatic activities in all the media tested. A simultaneous process of adsorption by the mycelium and degradation of extracellular enzymes was observed. A decrease of more than 90% COD was observed and the effluent generated showed no algal growth toxicity.

The safety disposal of high-level radioactive waste (HLW) has become an important issue for nuclear energy and environmental protection. Water chemistry and environmental isotope are accepted as feasible ways to trace groundwater circulation; it can effectively reveal the conversion relationship between different groundwater of the disposal site. Geochemical and isotopic tracers were used to constrain origins and chemical evolution of groundwater in the arid fissure system of the Xinchang preselected site for high-level radioactive waste geological disposal in China. Groundwater level, water temperature, and water chemistry information at different depths were obtained by multi-layer groundwater monitoring. The results show that the chemical and isotopic composition of groundwater in this fissure system is mainly controlled by evaporation, the water chemistry type of the shallow groundwater is mainly Na-Cl-SO₄ or Na-Ca-Cl-SO₄, and the deep groundwater is mainly Na-Cl-SO₄. Based on the values of monitoring data in deep borehole, the fluctuation of groundwater level is less than 0.40 m with weak hydrodynamic condition, and the geothermal gradient is 1.91 °C/100 m. The isotope analyses indicate that the groundwater in the system recharged by local atmospheric precipitation, and the deep groundwater recharged capacity of the site is weak and with no deep cycle.

The current study aimed to investigate the efficiencies and mechanisms of slag filter media for removing phosphorus from synthetic wastewater. The steel slag with high ferric oxides (Fe₂O₃) was subjected for the electric arc furnace (EAF) and selected as the filter media (HFe). The chemical characteristics of HFe were determined using pH, point of zero charge (PZC) and XRF. The phosphorus removal efficiency was studied in a designed vertical steel slag column rock filters in unaerated HFe (UEF) and aerated HFe (AEF) system. The microstructure of HFe was analyzed by FTIR, XRD and SEM-EDX analysis. The results of XRF revealed that ferric oxide (Fe₂O₃) ranged from 26.1 to 38.2%. PZC for Filter HFe was recorded at pH 10.55 ± 0.27. The highest efficiencies were recorded by UEF and AEF systems at pH 3 and pH 5 (89.97 ± 4.02% and 79.95 ± 6.25% at pH 3 and 72.97 ± 8.38% and 66.00 ± 12.85% at pH 5 for UEF and AEF, respectively). These findings indicated that AEF exhibiting higher removal than UEF systems might be due to presence high Fe concentration in AEF which play important role in the phosphorus removal. The main elements available on the surface of HFe included carbon, oxygen, iron, calcium, magnesium, silicon, platinum, sulphur, manganese, titanium and aluminium. The XRD analysis indicated that the precipitation of orthophosphate as calcium and iron-phosphates was the removal mechanism as confirmed using FT-IR analysis. These findings demonstrated the efficiency of HFe in removing of phosphorus from wastewater.

The Balkan Peninsula has rich biodiversity with a large number of endemic species; therefore, a part of its territory has been recognized as a World Biodiversity Hotspot. Despite nature conservation efforts and development of nature conservation networks in countries of the region, anthropogenic influence on natural and semi natural ecosystems is increasing. Moreover, new types of disturbance and pollution arise, and one of the more recent being artificial light at night (ALAN) which has serious consequences on reproduction, navigation, foraging, habitat selection, communication, trophic and social interactions of the biota. We have estimated the level of ecological light pollution in the strict protected areas of the Republic of Serbia, the Republic of Bulgaria, and Montenegro using available Google Earth Pro tools, and the New World Atlas of Artificial Sky Brightness (2016) in the form of a kmz layer. The research has covered 13 National Parks, 11 Nature Parks and 55 Reserves. Our results showed widespread incursion of ALAN within strict protected areas in the studied region that has also been noted for some other countries and regions too. However, the level of light pollution is lower here, than in the most part of Continental Europe, and there are a few areas in each country where the night sky above National and Natural Parks is almost dark. These territories have a special value for nature conservation; therefore, it is important to save the dark night sky there.

To examine the status and risk of heavy metal pollution in an urban wetland in China, the distribution and speciation of chromium (Cr) and other metals (Cd, Cu, Pb, and Zn) were examined. We investigated the impact of three major land uses (residential and industrial (RI), orange plantation (OP), and mixed OP and RI (OPRI)) on the heavy metal characteristics using sediment cores (0–60 cm below water/sediment interface) collected in Sanyang Wetland, China. It was found that all the metals (Cr, Cd, Cu, Pb, and Zn) had lower concentrations in the top layers but higher contents in the bottom layers of sediments. Species of metals in sediments were dominated by their secondary phase (i.e., exchangeable and carbonate bound, Fe-Mn bound and organic bound) with relatively low contents of primary phase (i.e., residual form), except for Cr in RI affected river sediments that had a relatively high content of primary phase (20.97–36.07%). The ratio of secondary phase to primary phase (RSP) and risk assessment code (RAC) methods were applied to assess environmental risk. The results implied that the metal mobility and bioavailability could significantly cause urban wetland environmental quality decline, and thus enhanced strategies should be required to target the capture and removal of metals.