Drinking water reservoirs are threatened globally by anthropogenic nitrogen pollution. Hydrochemistry and isotopes were analyzed to identify spatial and temporal varieties of main nitrate sources in a large drinking water reservoir in East China. The results showed that NO₃⁻ was the main nitrogen form in both the dry and wet seasons, but dissolved organic nitrogen (DON) was increased in the wet season. The δ¹⁵N-NO₃⁻ values (+ 1.3‰ to + 11.8‰) and δ¹⁸O-NO₃⁻ values (+ 2.5‰ to + 13.5‰), combined with principal component analysis (PCA), indicated that chemical fertilizer was the main nitrate source during the dry season, while chemical fertilizer, soil N, and sewage/manure were the main nitrate sources during the wet season in the Qiandao Lake area. And, the nitrate isotopes showed the significant nitrification and assimilation in the Qiandao Lake area. A Bayesian isotopic mixing model (Stable Isotope Analysis in R) was applied to the spatial and seasonal trends in the proportional contribution of four NO₃⁻ sources (chemical fertilizer (CF), soil nitrogen (SN), sewage and manure (SM), and atmospheric deposition (AD)) in the Qiandao Lake area. It was revealed that CF was the most important nitrate source in the dry season, accounting for 53.4% with 19.2% of SM and 18.9% of SN, while the contribution of SN increased in the wet season, accounting for 31.6%, followed by CF (30.8%) and then SM (24.2%). The main nitrate sources in the urban area, rural area, and central lake area were CF and SN, accounting for 66.1% in the urban area, 71.7% in the rural area, and 68.2% in the central lake area. Measures should be made to improve chemical fertilizer use efficiency and to reduce nitrogen loss in the Qiandao Lake area. Graphical abstract .

Metal-contaminated sediments in lakes is a global concern that poses toxicological risk to aquatic organisms. This study performed bioassays using the submerged macrophyte, Vallisneria natans (Lour.) Hara, exposed to contaminated sediments collected from five locations in Dianchi Lake, Yunnan, China. Among the sediments collected, Igₑₒ showed enrichment of As and Cd in Dianchi Lake sediments. In spite of enriched toxic metals at some locations, laboratory bioassays found no significant difference in leaf biomass or leaf photosynthesis rate between the sites. Root biomass and root activity showed significant differences between locations and were negatively correlated with the concentration of As, Cd, Hg, and Pb in sediment but not related to Cr. The above correlations were strongest for Hg and As, respectively. Accumulation of Cd and Pb to leaves of bioassay plants was observed, but this was not evident for As and Cr. Overall, the results indicate that V. natans can be used as a bioassay organism and measures of root toxicity are sensitive to metal concentrations present in Dianchi Lake sediments. Furthermore, the study species holds promise for use as a biomonitor of Cd and Pb sediment metal content.

Methane (CH₄) is an important greenhouse gas (GHG), and paddy fields are major sources of CH₄ emissions. This pot experiment was conducted to investigate the integrated effects of Azolla inoculation combined with water management and N fertilization on CH₄ emissions in a double-rice cropping system of Southern China. Results indicated that midseason aeration reduced total CH₄ emissions by 46.9%, 38.6%, and 42.4%, followed by N fertilization with 32.5%, 17.0%, and 29.5% and Azolla inoculation with 32.5%, 17.0%, and 29.5%, on average, during the early, late, and annual rice growing seasons, respectively. The CH₄ flux peaks and total CH₄ emissions observed in the late rice growing season were significantly higher than those in the early rice growing season. Additionally, CH₄ fluxes correlated negatively to soil redox potential (Eh) and dissolved oxygen (DO) concentration. Azolla inoculation and N fertilization greatly increased the rice grain yields, whereas midseason aeration had distinct effects on grain yields in both rice seasons. The highest annual rice grain yields of approximately 110 g pot⁻¹ were obtained in the Azolla inoculation and N fertilization treatments. In terms of yield-scaled CH₄ emission, Azolla inoculation combined with midseason aeration and N fertilization generated the lowest yield-scaled CH₄ emissions both in the early and in the late rice growing seasons, as well as during the annual rice cycle. In contrast, the highest yield-scaled CH₄ emission was obtained in the treatment employed continuous flooding, without Azolla and no N application. Our results demonstrated that Azolla inoculation, midseason aeration, and N fertilization practices mitigated total CH₄ emissions by 18.5–42.4% during the annual rice cycle. We recommend that the combination of Azolla inoculation, midseason aeration, and appropriate N fertilization can achieve lower CH₄ emissions and yield-scaled CH₄ emissions in the double-rice growing system.

Antibiotics have a wide application range in human and veterinary medicines. Being designed for pharmacological stability, most antibiotics are recalcitrant to biodegradation after ingestion and can be persistent in the environment. Antibiotic residues have been detected as contaminants in various environmental compartments where they cause human and environmental threats, notably with respect to the potential emergence and proliferation of antibiotic-resistant bacteria. An important component of managing environmental risk caused by antibiotics is to understand exposure of soil and water resources to their residues. One challenge is to gain knowledge on the fate of antibiotics in the ecosystem along the soil-water continuum, and on the collateral impact of antibiotics on environmental microorganisms responsible for crucially important ecosystem functions. In this context, the ANTIBIOTOX project aims at studying the environmental fate and impact of two antibiotics of the sulfonamide class of antibiotics, sulfamethazine (SMZ), and sulfamethoxazole (SMX).

ZnAl-layered double hydroxide-loaded banana straw biochar (ZnAl-LDH-BSB) was prepared via the hydrothermal method, and the efficient phosphorus removal agent ZnAl-LDO-BSB was obtained by calcination at 500 °C. Based on the ZnAl-LDO-BSB adsorption characteristics, the adsorption mechanism was evaluated via TG/DTA, FTIR, XRD, SEM, HRTEM, and other characterization methods. The results showed that the ZnAl-LDO-BSB assembled into microspheres with typical hexagonal lamellar structures and presented good thermal stability. The adsorption of total phosphate (TP) by ZnAl-LDO-BSB conforms to the Langmuir model, and the theoretical maximum adsorption capacity is 185.19 mg g⁻¹. The adsorption kinetics were in accordance with the second-order kinetic model, and the anion influence on TP adsorption followed the order CO₃²⁻ > SO₄²⁻ > NO₃⁻. The combination of zeta potential measurements with the FTIR, XRD, SEM, HRTEM, and XPS results suggested that ZnAl-LDO-BSB adsorbs TP mainly by electrostatic adsorption, surface coordination, and anion intercalation. Graphical abstract

Global warming and greenhouse gas emissions have become a severe threat to our ecosystem. Prior studies on environment posit that ample exhaustion of fossil fuels for energy is one of the fundamental causes of environmental degradation and naturally replenished energy sources are affordable over fossil fuels. This study set out to examine the role of financial sectors and globalization (in the presence of energy and renewable energy consumption) for a sustainable environment in the panel of Central and Eastern European (CEE) countries in One Belt and One Road initiative perspective. The current study uses annual data of 16 CEE countries covering the period of 1980 to 2016. After confirmation of cross-sectional dependency and co-integration among variables, we applied the Dynamic Seemingly Unrelated Regression and Dumitrescu–Hurlin causality approach for long-run estimations and to check the causal relationship, respectively. The empirical findings of the study certify the existence of an environmental Kuznets curve for the selected panel countries. Globalization is enhancing the environmental quality of the CEE economies. It is important to note that energy consumption and renewable energy consumption have a positive and statistically significant whack on carbon emission. In addition, we do not find a significant link between financial development and carbon emission. Granger casualty test confirms a two-way causal relationship between economic growth and carbon emission, globalization and environmental degradation, globalization and renewable energy consumption, economic growth and renewable energy consumption, and between financial development and energy consumption. Moreover, we found one-way causality from energy consumption (renewable and non-renewable) to carbon emissions. Based on the findings, a number of appropriate policy suggestions are presented in the perspective of Central and Eastern European Countries.

Se can regulate Cd accumulation and translocation in plants; however, such effects can be controversial because of the differences in plant species and Se species. In this study, pak choi was cultured under hydroponic conditions, and the effects of selenite and selenate on Cd accumulation were investigated in the edible parts of this vegetable. The results showed gradual improvements in the effects of the two Se species on the Cd content in pak choi shoots at the four assessed growing stages. Selenite did not lead to significant changes in Cd accumulation in the shoots until day 40, when it significantly reduced the accumulation by 34%. Selenate was always found to increase the Cd content in the shoots, and the differences on days 19 and 40 were 16% and 45%, respectively, compared with those of the Cd (only) treatment. Accordingly, selenate invariably enhanced Cd translocation from the roots to the shoots, whereas selenite insignificantly reduced the translocation only on day 40. Generally, selenomethionine (SeMet) accounted for much larger proportions in selenite-treated plants, while SeO₄²⁻ was the dominant Se species in selenate-treated plants. However, under both Se treatments, the SeMet proportion increased substantially from day 19 to day 40 when that of SeO₄²⁻ exhibited a drastic decrease; therefore, the relative proportion of seleno-amino acids to SeO₄²⁻ may be the key factor for the regulation of Cd accumulation in pak choi via treatment with selenite and selenate at the different growing stages.

This study investigated a previously developed thermophilic microbial community with the ability to effectively degrade azo dyes. To identify the key microbes of this microbial community, a dilution-to-extinction approach was combined with polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and Illumina high-throughput sequencing technology (HTST). Strains belonging to Tepidiphilus sp. almost disappeared from the degradation solution at dilution ratios above 10⁻⁷; furthermore, at this ratio, the diluted microbial community almost lost their decolorization ability, indicating this ratio as the critical point for effective azo dye decolorization. Strains belonging to Tepidiphilus sp. were indicated as possible key functional microbes of this microbial community for effective azo dye decolorization. Moreover, the synergistic action of other microbes, such as Anoxybacillus sp., Clostridium sp., and Bacillus sp., was suggested to further promote the decolorization process by secreting azoreductase and laccase. Caloramator spp. were found have the ability to degrade proteins and amino acids, which might promote the degradation process with further degradation microbes. The loss of these bacteria might diminish the synergistic relationships among different strains, which further results in the failure of efficient azo dye decolorization and degradation by this microbial community.

The hazel bolete Leccinellum pseudoscabrum (Kallenb.) Mikšík 2017 specimens and beneath soil layer (0–10 cm) have been examined on the occasion of ²¹⁰Po and ²¹⁰Pb activity concentrations, the nuclide bioaccumulation potential by species and distribution in fruit bodies. Mushrooms and forest soils came from six geographically distant locations in the northern and central parts of Poland. The threat to humans from ²¹⁰Po and ²¹⁰Pb contained in mushrooms has been also assessed. The absolute values of the ²¹⁰Po radioactivity, respectively, in caps and stems of fruit bodies were in the range 0.74 ± 0.06–8.59 ± 0.36 Bq kg⁻¹ dry biomass and from 0.81 ± 0.06–8.23 ± 0.37 Bq kg⁻¹ dry biomass, while the values of the ²¹⁰Pb radioactivity in caps and stems were in the range 0.61 ± 0.04–6.33 ± 0.22 Bq kg⁻¹ dry biomass and 0.83 ± 0.04–4.59 ± 0.24 Bq kg⁻¹ dry biomass, respectively. A potential related effective dose assessment showed that mushrooms L. pseudoscabrum can contribute at 0.89–10.3 μSv kg⁻¹ db from ²¹⁰Po decay and 0.42–4.37 μSv kg⁻¹ db from ²¹⁰Pb decay.

In the present work, an experimental investigation was conducted to study the influence of adding aluminum oxide nanoparticles (Al₂O₃) with different average particle sizes as additive to blends of diesel and waste plastic oil (WPO) on performance, emission, and combustion attributes of single-cylinder diesel engine operated at a constant speed. Two samples of Al₂O₃ nanoparticle with average particle sizes of 20 and 100 nm were dispersed into a WPO20 blend containing 20% of WPO and 80% of diesel in the mass fractions of 10 and 20 ppm using ultrasonic stabilization. The experimental recordings revealed a decrease in engine performance and increase in all emission constituents while replacing diesel with WPO20. However, the addition of both 20- and 100-nm-sized Al₂O₃ nanoparticles into WPO20 was found to enhance the brake thermal efficiency (BTHE) by 12.2 and 8.9% respectively and decrease the brake-specific fuel consumption (BSFC) by 11 and 8% respectively. The emission constituents such as carbon monoxide (CO), hydrocarbons (HC), nitric oxide (NO), and smoke opacity were minimized by the addition of both 20- and 100-nm-sized nanoparticles into WPO20 blend. However, the reduction of emissions was better for 20-nm-sized particles compared with that of 100-nm-sized particles. The combustion attributes such as cylinder pressure, heat release rate (HRR), and rate of pressure rise (RPR) were raised with shortened ignition delay (ID) by the addition of both sized nanoparticles. Overall, the inclusion of 20-nm-sized nanoparticles performs better catalytic activity to enhance the engine output characteristics along with minimum exhaust emissions.