In this study, amine-terminated hyperbranched PAMAM (polyamidoamine) polymer (AT-HBP) was synthesized as a multifunctional chelating agent to remove two heavy metal ions (Cr(III) and Cu(II)) from the simulated wastewater solutions. The AT-HBP was characterized by Fourier transformed infrared (FTIR), dynamic light scattering (DLS), and proton nuclear magnetic resonance (¹H NMR) analysis. The removal process was carried out in two different methods, centrifuged process and ultrafiltration. The concentration of heavy metal ions before and after removal was measured by inductively coupled plasma (ICP) instrument. The removal processes were evaluated by changing different parameters such as solution pH, AT-HBP dosage, and metal ion concentration. To evaluate the extend of binding of heavy metal ions in the presence of AT-HBP the presence of salt in the solution was also examined on the performance of the removal system. The overall results indicated that removal percentages higher than 98% for Cr(III) and 86% for Cu(II) were achieved for heavy metal concentrations of 100 mg/L for both removal process methods. Furthermore, the function of second generation of polypropylenimine (PPI) was compared to AT-HBP. The results reveal that the removal of Cr(III) and Cu(II) ions by AT-HBP were approximately 20% and 10% higher compared to PPI, respectively. Finally, hyperbranched dendritic polymer with lower expenses to synthesize compared to dendrimer underlined favorable properties as a multifunctional chelating agent and enhancement of ultrafiltration process for wastewater treatment. Graphical abstract

The activity of enzymes in soil is sensitive to the changes in soil properties affected by biotic and abiotic factors. This study investigates the influence of salinity on some enzymes (catalase CAT, dehydrogenases DEH, alkaline AlP, and acid AcP phosphatase) and pH in 0.01 M CaCl₂, ECₑ, the content of total organic carbon, and total nitrogen in technogenic salinization soil next to the soda plant. Seven soil sampling sites were selected (S1–S6) in the area close to the soda plant and C (the control). Based on the enzyme activity, also soil indicators were calculated: the resistance index (RS), enzymatic pH indicator [Formula: see text], the factor of the impact of anthropopressure (IF), the biological index of fertility (BIF), and the indices of biochemical soil activity (BA12 and BA13). The above study did not show one-way changes of the parameters investigated. The relations between the parameters and the activity of catalase, dehydrogenase, alkaline, and acid phosphatase show that they are mostly determined by the state of salinity of the soil environment. The calculated index of resistance (RS), as an effective means of the enzymatic response to environmental stress, facilitated putting the enzymes in the following series: CAT>DEH>AlP>AcP. It shows that catalase and dehydrogenases are most resistant to the anthropogenic factor. The calculated values of BA12 and BA13 indices showed the differences between technogenic salinization soils and the soil sampled from the control. The lowest BIF values were observed at S6 and S3, S4, and C.

Three landfills are located in the eastern part of the Chengdu City, and two traffic tunnels pass beneath the south portion of landfill-1. The landfills have a simple leachate collection system without any bottom liner and impermeable wall, which causes a severe corrosion of the traffic tunnels from 175 to 250 m in the test section. In order to explore how the traffic tunnels impact the transport path of contaminants infiltrating from landfills, a groundwater flow model and a solute transport model were established in the present study. It was found that, after 16 years of operation, the traffic tunnels will accelerate the vertical migration of sulfate ions in the area between the tunnels. Furthermore, 64 water samples along the traffic tunnels were collected to test the concentration of the contaminants. According to the distribution mechanism of the measured concentrations in the traffic tunnels, a preliminary treatment plan was proposed to control the further corrosion of the tunnels and the spread of the contaminants.

Phosphogypsum (PG) accumulation occupies huge amounts of land resources and results in serious environmental risks. A new recycling product, the phosphogypsum embedded filler (PGEF) made with calcination-modified phosphogypsum, was developed. The preparation process, hydration mechanism of PG, basic physical performances, environmental safety, engineering application, and cost analysis of the PGEF were studied. The results showed that the stress performance and thermal insulation property of the products were satisfied. Environmental performance tests established their findings that the application of PGEF prepared with calcination-modified PG does not cause any secondary contamination. In addition, the cost of PGEF is far lesser than that of the same volume of reinforced concrete. PGEF prepared with calcination-modified PG has shown a perfect application in cast-in situ concrete hollow floor structure.

Graphene oxide (GO) was prepared, characterized, and applied for adsorption of Sr(II) in aqueous solution. The adsorption capacity was calculated to be 137.80 mg/g according to the Langmuir model. The observation by scanning electron microscope with energy dispersive X-ray detector (SEM-EDX), high-resolution transmission electron microscope (HRTEM), and X-ray diffraction (XRD) revealed the crystal structure of Sr compound on the surface of graphene sheets. The analyses by the Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) indicated the involvement of O–C=O, C–O, and C–O–C groups during the adsorption. The X-ray absorption fine structure (XAFS) analysis provided the detail information of GO-Sr composites, and the fitting results were given by Sr(HCOO)₂ and SrCO₃ model, and the coordination numbers (CN) and interatomic distances (R) of Sr–O shell and Sr–C shell were calculated. The adsorption mechanism of Sr(II) was attributed to complexation between Sr and the acidic oxygen-containing groups, which lead to the agglomeration of graphene oxide. Two types of crystals were proposed. Type 1 was formed by coordination between Sr(II) and O–C=O groups, and type 2 was formed by coordination between Sr(II) and C–O/C–O–C groups.

Cadmium (Cd) toxicity has detrimental effects on plant metabolism and yield formation. This study examined the effects of Cd stress in rice and the possible role of calcium (Ca) in mitigating oxidative damage caused by Cd in two fragrant rice cultivars, i.e., Guixiangzhan and Meixiangzhan 2. The experimental treatments were composed of various Ca and Cd levels as individual, i.e., Ca at 2.5 and 5.0 mg/kg soil (Ca1 and Ca2, respectively), Cd at 50 and 100 mg/kg soil (Cd50 and Cd100, respectively), and combined, i.e., Ca1+Cd50, Ca1+Cd100, Ca2+Cd50, and Ca2+Cd100. Plants without Ca and Cd application were taken as control (CK). Results showed that Cd stress led to a substantial decline in the photosynthetic pigments, i.e., Chl a, Chl b, and carotenoids, while enhanced oxidative damage in terms of increased levels of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) and electrolyte leakage (EL) in both rice cultivars. Moreover, Cd stress hampered the activities of enzymatic antioxidants, i.e., superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), with lowest antioxidant activities were recorded at Cd100. The overall trend (lowest to highest) for antioxidant activities across treatments was recorded as Cd100 < Ca2+Cd100 < Cd50 < Ca1+Cd100 < CK < Ca1 < Ca1+Cd50 < Ca2+Cd50 < Ca2. Similarly, Ca amendment improved the proline, soluble protein, and soluble sugar contents in both rice cultivars under Cd stress condition. Comparing Ca2 with CK, the yield and related components, i.e., number of panicles, spikelets per panicle, seed setting rate, 1000 grain weight, and grain yield, were found to increase by 13.08, 2.39, 4.03, 5.86, and 27.53% for Guixiangzhan and 16.48, 5.19, 6.87, 15.44, and 51.16% for Meixiangzhan, respectively. Furthermore, Cd contents in roots, stems, leaves, and grains increased with increased Cd concentration applied and reduced with Ca amendment. The Cd contents in grains for all Ca+Cd levels are statistically at par with each other and significantly lower (P < 0.05) than those for individual Cd application. Hence, Ca amendment can be an appropriate approach to ameliorate the toxic effects of Cd in crops grown under Cd-contaminated soils.

The main objective of the present study is to introduce a new and ecologically safe method for managing the rice weevil, Sitophilus oryzae. Therefore, the Agave americana leaf extract’s phytochemical profile, and its insecticidal activity against the adults of S. oryzae were evaluated. The A. americana leaf extract was screened for the following phytochemicals: total phenolics (14.70 ± 0.31 mg GAE/g FW), total flavonoids (5.15 ± 0.18 mg RE/g FW) and saponins (10.32 ± 0.20 mg OAE/g FW). The HPLC-ESI/TOF-MS analysis results revealed that flavonoid glycosides (kaempferol, quercetin, and isorhamnetin derivates) were the major phenolic compounds of the A. americana leaf extract. In addition, the GC-MS analysis identified n-alkanes (77.77%) as significant compounds of the lipophilic fraction from the leaf extract. Moreover, the insecticidal potential was assessed through contact and repellent bioassays towards the rice weevil adults. The LD₅₀, LC₅₀, and RC₅₀ values were 10.55 μg/insect, 8.99 μg/cm², and 0.055 μg/cm² for topical application method, treated filter-paper method, and repellent bioassay, respectively. Furthermore, the A. americana leaf extract inhibited digestive enzyme activities, and median inhibition concentrations IC₅₀ were evaluated to be 146.06 ± 1.74 and 86.18 ± 1.08 μg/mL for α-amylase and protease, respectively. Overall, our results highlighted the promising potential of the leaf extract against S. oryzae adults, allowing us to recommend the extract under investigation as an ecofriendly alternative to synthetic insecticides.

The article Re-evaluating the environmental impacts of tourism: does EKC exist?, written by Jeyhun I. Mikayilov, Shahriyar Mukhtarov, Jeyhun Mammadov and Mayis Azizov

The Argentine giant tegu, a large lizard native to South America, was first discovered as established in the USA in scrub habitats of west-central Florida in 2006. Invasive populations potentially could occupy an extensive range of habitats and in much of the southern United States and Mexico and threaten many native species. The Argentine giant tegu was recently deemed as having a “highest impact concern” among the invasive reptile species most threatening to Florida ecology. Among the most rewarding research directions identified for this species was “having a reliable and practical method to detect/monitor” them. We address this need by evaluating five methods for monitoring Argentine giant tegus on how well each method detected the species and whether the observations were sufficient to quantitatively assess population abundance using a widely applicable framework for indexing animal populations. Passive tracking plots were the most efficient and effective means for detecting tegus and calculating abundance indices but were best suited for late winter to spring before summer rains compacted tracking substrates. Gopher tortoise burrows are often used by tegus and camera traps on their entrances proved able to obtain data suitable for indexing populations but required more labor and expense than tracking plots. Trapping either at gopher tortoise burrows or along drift fences was ineffective at capturing tegus. Similarly, visual encounter transects were not effective for observing tegus.

Shengjin Lake is a typical lake wetland in the lower reaches of the Yangtze River. It is one of the most important wetlands in the world. It is also an important habitat for wintering cranes in China. Environmental factors play an important role in habitat selection of cranes of wetland ecosystem. In this paper, we analyzed land-use types and the four kinds of winter cranes in the Shengjin Lake from the years 1986 to 2015. Also, we adopted grey relational analysis and power function model to analyze the relevance between crane population and land-use types, and the main habitat types of cranes were obtained. We used principal component analysis method to analyze the main influence factor for habitat selection of crane. The results indicated that the main habitat type of four species of overwintering crane was reed-flat; the main factors affecting the habitat selection of cranes were water level, planktonic biomass, and distance to settlement. Among them, the weight of water level factor was the highest, which showed that water level was the most important factor affecting the habitat selection of cranes, followed by planktonic biomass, and the third was the weight of distance to settlement. The average values of them were 0.37 m, 9.47 mg L⁻¹, and 1.25 km, respectively.