The field experiment of a rice–wheat rotation system was conducted on a coastal reclaimed farmland with different application rates of biogas slurry from a large-scale standardized hoggery. Crop yield, grain quality, and soil properties were examined to determine the appropriate application rate. At the slurry application rates of 480 m³ ha⁻¹ for rice and 9.00–11.25 m³ ha⁻¹ for wheat, grain yields of rice and wheat were 8.9 and 15.7% higher than those under conventional fertilization, respectively. When 840 m³ ha⁻¹ biogas slurry was applied to the rice field, the grain amino acid content was significantly higher than that of conventionally fertilized rice. In the rice–wheat rotation system, under biogas slurry treatments, soil pH and EC did not significantly increase; the contents of soil Pb, Cr, Cu, and Zn were within allowable limits; the contents of soil alkali-hydrolyzable nitrogen were greatly increased and significantly higher than those under conventional fertilization treatment; and the content of soil organic matter had no significant difference with that under no fertilization treatment. Therefore, the recommended application rate of biogas slurry on coastal reclaimed farmland should be 480 and 9.00–11.25 m³ ha⁻¹ for rice and wheat, respectively.

In the study, an activated carbon was prepared by co-pyrolyzing rice straw and sewage sludge with ZnCl₂ activation (SS-RS AC) and used to remove Cr(VI) from wastewater. Firstly, for the preparation of SS-RS AC, the yield and iodine number were used to determine the appropriate addition percentage of rice straw. Then, a series of batch experiments including initial pH, adsorption kinetics and isotherms, and ionic strength as well as Fourier transform infrared (FT-IR) analysis of SS-RS AC before and after adsorption were performed to explore the Cr(VI) adsorption removal behavior and mechanism of SS-RS AC prepared from sewage sludge with the appropriate rice straw addition percentage. The results showed that the appropriate addition percentage of rice straw was 20%. For the Cr(VI) adsorption removal with SS-RS AC, the initial pH of solution significantly influenced the removal efficient. The highest efficiency of Cr(VI) adsorption removal (97.7%) could be attained at pH 2.0. The adsorption kinetics and isotherm data were best fitted by the pseudo-second-order model and the Langmuir-Freundlich model, respectively. The prepared SS-RS AC had the maximum Cr(VI) adsorption removal capacity of 138.69 mg/g at 40 °C. The main mechanisms for the Cr(VI) removal with SS-RS AC involve the electrostatic attraction and the reduction of Cr(VI). Carboxy, amine, and hydroxyl groups were found to act as electron donor groups, contributing to the reduction of Cr(VI). The ionic strength had an adverse effect on the Cr(VI) removal. Overall, the prepared SS-RS AC can be used as an alternative and low-cost adsorbent for the removal of Cr(VI).

A plethora of empirical work explored finance-income-environment nexus, aims to investigate high CO₂ emissions determinants, over the last few couples of decades. The prior empirical work assist the idea that finance and income have diverse impacts on the environment. The lack of consensus on finance-income-environment nexus in the Central and Eastern European Countries in the perspective of Belt and Road Initiative need to be examined. Therefore, the present study explores the nexus between financial development, income level, and environmental quality for a panel of eighteen Central and Eastern European Countries, over the period of 1980–2016. The Dynamic Seemingly Unrelated Regression, the Fully Modified Ordinary Least Squares, and the Dumitrescu-Hurlin panel casualty approaches are employed. The environmental Kuznets curve hypothesis also investigated for both time series panel and country-wise. The Dynamic Seemingly Unrelated Regression long-run panel results reveal that (i) financial development index and income negatively impact on environmental quality; (ii) energy consumption is the key determinant of CO₂ emissions and reduces environmental quality; (iii) urbanization and trade both enhance environmental quality via reduction of carbon emissions; and (iv) the environmental Kuznets curve hypothesis supported for the selected panel countries. The country-wise results depict that increase in environmental quality occurs due to increase in financial development (in four countries), income level (in five countries), trade (in five countries), and urbanization (in eight countries). However, the environmental quality decreases due to the increase in financial development (in six countries), income level (in eight countries), energy consumption (in twelve countries), trade (in six countries), and urbanization (in five countries). The environmental Kuznets curve hypothesis supported for five Central and Eastern European Countries. Additionally, the causality results confirmed the presence of feedback relationships among income and environmental quality, and financial development and energy consumption. Thus, we conclude that income level and financial development are the main drivers behind high carbon dioxide emissions in CEECs. The finding of the study opens up new insight for appropriate policymaking.

To reduce the environmental pollution caused by ammonium paratungstate (APT) production in the Ganzhou area in China, simulated experiments in laboratory and field experiments in cement kilns were performed. The migration characteristics of As in secondary residues (thermometallurgy and hydrometallurgy residues) from APT production in cement kilns were similar, and As in the residues existed in the form of sulfides. When the residues were fed at the kiln inlet, the As in the residues was completely distributed in the clinker after a new mass balance of As was reestablished in a very short time. When the residues were fed at the raw mill, the total input rate of As was far higher than the total output rate. Therefore, a part of As was circulated in the cement kiln, and only a small part of As was distributed in the clinker. In addition, the As concentration in the flue gas and the leaching concentration of As in the clinker were far below the limit value in the Chinese standard. For feeding rates below that are used in the field experiment, co-processing of secondary residues in a cement kiln fed at the kiln inlet is environmentally safe. However, if the secondary residues are consistently fed at the raw mill, the As concentration in the flue gas may gradually increase.

In this study, we screened for the antifouling activity of 15 species plant extracts from Brazilian the Brazilian Caatinga Fabaceae against the initial colonization of natural marine bacterial biofilm. We also investigated the potential toxicity of extracts against planktonic and benthic non-target organisms. Aqueous extracts of plants collected in the Caatinga biome (PE, Brazil) were prepared and tested at different concentration levels (0, 0.5, 1, 2, 4, and 8 mg mL⁻¹). Natural marine bacterial consortium was inoculated in multi-well plates and incubated with the different treatments for 48 h. The biofilm and planktonic bacterial density and biomass inhibition were evaluated along with biofilm biomass eradication. The extracts that showed the highest bacterial biofilm inhibition were evaluated for toxicity against microalgae and crustaceans. The biofilm and planktonic bacterial inhibition potential were evaluated through flow cytometry and spectrophotometry. The selected treatments were evaluated for their toxicity using the microalgae Chaetoceros calcitrans, the copepod Nitokra sp., and the brine shrimp Artemia salina as bioindicators. Our work demonstrates the biotechnological potential of Fabaceae plant compounds as a safe antifouling alternative. Anadenanthera colubrina var. cebil fruits and Apuleia leiocarpa leaf extracts showed antibiofilm activity (≥ 80%), while Myroxylon peruiferum and Dioclea grandiflora leaf extracts showed antibiotic activity. These extracts were safe to planktonic and benthic non-target organisms. The results of this study point to potential substitutes to highly toxic antifouling paints and shed light on the prospect of a yet to be explored biome for more sustainable alternatives in biofouling research.

A pot experiment was performed to examine the role of foliar applied mannitol (M) in chromium (Cr) stress alleviation in different maize cultivars. Two maize cultivars, one tolerant (6103) and one sensitive (9108) to chromium stress, were grown in soil treated with three concentrations of Cr (0, 5, and 10 mg kg⁻¹) and three levels of mannitol (0, 50, and 100 mg L⁻¹). Chromium stress decreased the overall growth of plants by reducing the plant height, root/shoot dry weight, chlorophyll contents, and enzymatic activities, while exacerbated the severity of reactive oxygen species in both maize cultivars. Chromium-induced reduction in growth attributes of maize plants was relatively higher in sensitive cultivar than that of tolerant one. Uptake of Cr by the plants and its translocation from roots to shoots increased with increasing concentration in the soil. However, foliar application of mannitol significantly alleviated the Cr stress and improved growth, biomass, and photosynthetic pigments of maize plants. Mannitol also considerably reduced Cr contents in leaves and roots of both cultivars. Hence, it is concluded that mannitol can be helpful for crops grown on heavy metal, especially Cr, contaminated soils for remediation purpose.

Conventional air pollutants (PM₁₀, CO, NOₓ) gradually increased from fall to winter during 2015 in Istanbul. Several air pollution episodes were observed during this period. This study was made in order to determine polycyclic aromatic hydrocarbon (PAH) levels, identify the sources of air pollution, and make toxicity assessment based on Benzo(a)pyrene equivalent concentrations. The sampling took 14 sequential days during winter. High-pressure weather conditions prevailed at the start of the sampling. The conditions were then changed to low-pressure condition towards the end of the sampling. Strong inversion was effective on the onset of the sampling. Strong inversion was effective at the onset of the sampling. A high-volume sampler was used to collect gas and particle phase samples. Total suspended particle concentrations were between 27 and 252 μg m⁻³. Sixteen PAH species were investigated. Total (gas + particle) PAH concentrations were between 76.4 and 1280.3 ng m⁻³, with an average of 301.4 ng m⁻³. Individual PAH concentrations were between not detected (n.d.) and 99.2 ng m⁻³ in the gaseous phase, and between n.d. and 11.5 ng m⁻³ in the particle phase. Phenanthrene had the highest share among 16 PAH compounds. Benzo(a)pyrene was not detected in 8 days. On the remaining days, its concentration ranged between 5.5 and 14.8 ng m⁻³ with an average of 3.7 ng m⁻³. Low-molecular-weight PAHs dominated gaseous phase; inversely, high-molecular-weight PAHs dominated particle phase. Possible sources were identified by diagnostic ratios. These ratios suggested that coal combustion and diesel vehicle exhaust emissions had a substantial impact on ambient air quality. Benzo(a)pyrene equivalencies were calculated for each PAH compound in order to make toxicity assessment. Total benzo(a)pyrene equivalencies ranged between 0.4 and 30.0 ng m⁻³ with an average of 7.2 ng m⁻³.

Intermittent turbulent bursts have great impacts on sediment resuspension in coastal regions, tidal estuaries, and lakes. In this study, the role of turbulence structure on sediment resuspension was examined at Meiliang Bay of Lake Taihu, the third largest freshwater lake in China. The instantaneous three-dimensional velocity and suspended sediment concentrations were synchronously recorded by Acoustic Doppler Velocimetry (ADV) and Optical Backscatter Sensor (OBS) placed close to the lakebed. Statistical and quadrant analyses results revealed that the coherent structure contributed significantly to sediment particle entrainment. The intermittent burst events (dominant ejection and sweep) were the main energy source for sediment resuspension processes. 99.2% of turbulent sediment fluxes were triggered by ejection and sweep events, whereas the contributions coming from the outward interactions and inward interactions were relatively small. The large-amplitude burst events in the coherent structure dominated the influence on the sediment diffusion. Additionally, it was found that instantaneous sediment particle entrainment occurred earlier than the mean critical shear stress, which was induced by the stochastic nature of turbulence. The amount of sediment flux considering the turbulence characteristics was one or two larger magnitudes than the flux amount assessed by the time-averaged flow field, which indicated the critical shear stress approach might underestimate the sediment resuspension. Therefore, the influence of turbulence performance on sediment entrainment shall be seriously considered when evaluating sediment flux and internal nutrient loads in Lake Taihu.

Sodium alginate (SA) is a linear biopolymer, which is the nontoxic, biodegradable, and rich in carboxyl and hydroxyl groups. In the paper, the SA-based hydrogel bead was prepared by the cationic hectorite clay and anionic sodium alginate with a simple ionic gelation method under freeze-drying, and the adsorption properties were evaluated by the removal of copper ions from aqueous solutions. The composites were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm (BET), thermal analysis (TG), and Fourier transform infrared spectroscopy (FT-IR). The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data and the Langmuir, Freundlich, Dubinin–Radushkevich (D-R), and Temkin models were applied to describe the adsorption isotherms. The results showed that the adsorption process was found to follow the Freundlich isotherm model and the maximum sorption capacity was observed to be 160.28 mg/g under the initial concentration from 10 to 700 mg/L at 45 °C. Adsorption kinetics data fitted well with pseudo-second-order rate model. The porous structure of the composite was responsible for the adsorption of Cu²⁺ ions. But the adsorption ability could be improved by pH. Finally, the adsorption mechanism was suggested. Graphical abstract

Dissolved organic matter (DOM) can become a carrier of soil contaminants. Therefore, an understanding of the evolution and characteristics of DOM produced by Chinese milk vetch during green manuring is crucial. In this study, DOM solutions from 28 days’ manuring with three different organic materials were characterized using three-dimensional fluorescence excitation–emission matrix (3D-EEM) with parallel factor (PARAFAC) analysis, and ultraviolet–visible spectroscopy. With the green manuring milk vetch at flowering period (MVFP), the DOC and water-soluble cadmium (WS-Cd) in soil solution reached 1875 mg/l and 2.64 μg/l, respectively, on day 6 after manuring. The PARAFAC analysis modeled three components: protein-like (tryptophan) and two humic-like components (humic acid and fulvic acid); DOM produced by MVFP was primarily protein-like during the early stage of decomposition. The aromaticity and molecular weight of DOM in the MVFP treatment was lower than in the other treatments, which could promote the release of soil particle-adsorbed Cd to soil solution. Principal components analysis showed that aromaticity was the main factor affecting Cd solubility, and the negative linear correlation of aromaticity with WS-Cd reached 0.4827. The results of this study supported the idea that manuring with MVFP might accelerate Cd infiltration to deep soil with water under gravity.