To evaluate the possible effects of habitat type on crustacean plankton (hereafter zooplankton) biomass and body size, a 5-year study (2011 to 2015) was conducted during wet seasons in three habitats in Lake Poyang, China. The lacustrine habitat with the most stable hydrologic regime had the highest zooplankton biomass coinciding with the highest phytoplankton biomass. The riverine habitat with the lowest Secchi depth overall had the largest zooplankton body size, but high zooplankton biomass only in high water level years. The seasonally inundated floodplain habitats had the lowest zooplankton biomass and the smallest individual body size, coinciding with the lowest phytoplankton biomass and the highest predation pressure, the latter indicated by a low zooplankton: phytoplankton biomass ratio (ZB:PB). Multiple linear regression analyses indicated that pelagic zooplankton assemblages were primarily influenced by phytoplankton biomass in lacustrine habitat, by advection and turbidity in riverine regions, and by predation pressure in seasonally inundated floodplain region. We conclude that the importance of bottom-up and top-down effects on zooplankton biomass and body size varied with habitat type in Lake Poyang.

This work aims to evaluate radioactivity levels of 238U (²²⁶Ra), ²³²Th(²²⁸Ra), and ⁴⁰K and the associated radiological hazard indices, as well as to assess the current status and concentrations of heavy metals along the coastline of the Gulf of Suez, in order to identify potential sources of contamination and to construct radioactivity baseline for this area. Measurements of the activity concentrations of ²³⁸U(²²⁶Ra), ²³²Th(²²⁸Ra), and ⁴⁰K in Bq kg⁻¹ of the collected samples were carried out using high-purity germanium (HPGe) detector. Heavy metals in seawater, shore sediment, and algae samples were determined using ICP-OES. The average activity concentrations of ²³⁸U(²²⁶Ra), ²³²Th(²²⁸Ra), and ⁴⁰K were found to be 13.79 ± 0.75, 14.57 ± 1.15, and 128.9 ± 4.15 Bq kg⁻¹, respectively. The radiological hazard indices of absorbed dose rate in nGy h⁻¹ (D), annual effective dose rate in mSv y⁻¹, AED, radium equivalent activity in Bq (Raₑq), external and internal hazard indices (Hₑₓ, Hᵢₙ), and cancer risk factor were calculated and compared with the worldwide averages. The distribution patterns of annual effective dose (AED) at the Suez Gulf showed that the south east of the Gulf is characterized by higher AED. Water quality parameters (water temperature, salinity, pH, DO, and Eh) reveal that Suez Gulf was undoubtedly affected by the rate of the human activities. Heavy metal concentrations in shore sediments showed some variation within the study area and followed the following order: Fe > Mn > Zn > Al > B > Co > Ni > Pb > V > Cr > Mo > Cu > Cd. Furthermore, heavy metal concentrations indicated that northern part of the Gulf contains the highest levels of these metals compared to the southern one.

Biocementation of hazardous waste is used in reducing the mobility of contaminants, but studies on evaluating its efficacy have not been well documented. Therefore, to evaluate the efficacy of this method, physicochemical factors affecting stabilized hazardous products of in situ microbially induced calcium carbonate precipitation (MICP) were determined. The strength and leach resistance were investigated using the bacterium Pararhodobacter sp. Pb-contaminated kiln slag (KS) and leach plant residue (LPR) collected from Kabwe, Zambia, were investigated. Biocemented KS and KS/LPR had leachate Pb concentrations below the detection limit of < 0.001 mg/L, resisted slaking, and had maximum unconfined compressive strengths of 8 MPa for KS and 4 MPa for KS/LPR. Furthermore, biocemented KS and KS/LPR exhibited lower water absorption coefficient values, which could potentially reduce the water transportation of Pb²⁺. The results of this study show that MICP can reduce Pb²⁺ mobility in mine wastes. The improved physicochemical properties of the biocemented materials, therefore, indicates that this technique is an effective tool in stabilizing hazardous mine wastes and, consequently, preventing water and soil contamination.

Globalization has led countries to a strong interdependence among them, which is reflected in trade and capital flows. Simultaneously, in recent decades, the world is rapidly urbanizing. This dynamic has generated a process of economic growth with serious consequences for the environment, particularly in air quality. In this context, the objective of this research is to examine the causal link among carbon dioxide emissions per capita as a measure of air pollution, real per capita output, FDI, trade openness, and urbanization in 100 countries during 1980–2017. First, we used the cointegration test of Pedroni (JAMA 61:653–670, 1999) and Westerlund (JAMA 69:709–748, 2007) to find the equilibrium long and short term, respectively, and the Dumitrescu and Hurlin (JAMA 29:1450–1460, 2012) test to verify the direction of causality among the series. Second, we estimate the strength of the cointegration vector for individual countries through a dynamic ordinary least squares model (DOLS), and for country groups using a dynamic panel model with ordinary least squares (PDOLS). The results found indicate the existence of short- and long-term equilibrium among the variables globally and by groups of countries. The strength of the cointegration vector is strong in high and middle-high-income countries. At a global level, the results of the causality test suggest the existence of a unidirectional causal relationship that goes from output, urbanization, and FDI to air pollution, and a bidirectional relationship among trade and air pollution. These results are sensitive to the inclusion of the level of development of the countries. Our results suggest that the mechanisms to increase output, along with commercial and FDI flows, and urbanization are factors that play a relevant role in the determination of air pollution. Consequently, public policies should take these aspects into account in efforts to mitigate air pollution.

Road traffic accidents (RTAs) are accountable for 1.2 million deaths and road safety is the part of sustainable development goals, which aims to provide a safe, accessible, affordable, and sustainable transport system by 2030. This study discovered the nexus of road traffic fatalities (RTFs) with its determinants in Asia, Europe, and America. Vector error correction model established the causality of RTFs (Asia, Europe), urbanization (Asia), physicians (Asia, Europe), traffic law enforcement index (Europe, America), vehicles (America), and paved roads (America). Short-run bidirectional causality of RTFs was established with educational expenditures (Asia, Europe), GNI (Europe), and urbanization (Europe). The fall in RTFs was 0.359% (Europe) and 0.957% (America) for 1% rise in GNI. The RTFs were decreased by 0.498% (Europe) and 0.390% (America) due to 1% rise in urbanization. Education shows 0.952% reduction in RTFs in Europe. The 1% increase in the number of physicians causes 0.793% reduction in RTFs in America. The RTFs were increased by 0.617% and 1.705% for 1% rise in the number of vehicles in Asia and America. The fall in RTFs was 3.604%, 0.134%, and 0.950% for 1% rise in paved roads in Asia, Europe, and America, respectively. Results show a reduction of 0.744% (Asia), 0.712% (Europe), and 0.312% (America) in RTFs due to 1% increase in traffic law enforcement index. The governments of all countries should expand and improve their paved road network and increase the enforcement of traffic laws. The government should make strict traffic laws like regular inspection of vehicles, strict inspection for the driving license, electronic challan, and medical fitness of drivers. The government should ensure the medical checkup of drivers at subsidized rates. It is useful to include the traffic rules in the educational syllabus due to the significant role of law enforcement in road safety. The government should use different media channels for the awareness of the public about loss due to road accidents.

The removal of contaminants by iron-based nanomaterials was inevitably affected by the natural organic matter (NOM), which is one of the most abundant material on earth and exists in natural waters. This study was performed to investigate the main influence of humic acid (HA, representing NOM) on the behavior and reactivity of Ni/Fe nanoparticles in the removal of deca-brominated diphenyl ether (BDE209). Generally, the inhibitory effect of HA on the removal of BDE209 by Ni/Fe showed greater significance with an increase of HA concentration. The zeta potential and sedimentation experiments showed that the HA enhanced the dispersion and stabilization of Ni/Fe particles; however, the removal of BDE209 was found to be inhibited. Moreover, the corrosion capacity of the Ni/Fe nanoparticles showed a positive correlation with the effect of HA on the reactivity of Ni/Fe nanoparticles. Meanwhile, typical quinone compounds in HA had an adverse effect on the removal of BDE209. Additionally, the competitive adsorption experiments and characterization illustrated that the adsorption of HA by Ni/Fe nanoparticles was superior to BDE209. Overall, it was proposed that the corrosion of Ni/Fe was reduced as the contact between the nanoparticles and H₂O was hindered due to the surface of Ni/Fe was occupied by the adsorbed HA, and thus inhibited the reactivity of Ni/Fe nanoparticles in the removal of BDE209.

Many countries face a dilemma of economic growth and carbon emission mitigation, which is highly associated with energy consumption. In order to initiate effective policies for controlling carbon emissions, it is important to identify the key sectors in the value chain, thus proposing corresponding measures. To date, however, energy and carbon emissions have been studied mainly from a production or consumption perspective, with important interactions between sectors being seldom considered. In response, a new CO₂ flow model is presented in which input-output analysis and network theory are combined with multilevel indicators to identify the key sectors affecting carbon emissions in terms of total, immediate, and mediative centrality effects. The model is demonstrated with an analysis of 2007 and 2012 China sectoral data, showing that Production & Supply of Electric Power, Steam and Hot Water (PESH), Nonmetal Mineral Products (NMMP), and Coal Mining & Dressing (CMDG) played key roles in China’s carbon transfer network; the roles of Electronic & Telecommunications Equipment (ETET), Instruments & Office Machinery (IOMY), and Electric Equipment & Machinery (EEMY) had the largest immediacy effect; and, acting as key transmission sectors, PESH, Smelting & Pressing of Metals (SPOM), and NMMP controlled a large share of CO₂ transfer. The measures used are closely related to, and provide new insights into, the traditional indicators of sector centrality. At the same time, the proposed multilevel indicators are supplements for techniques that aim to instruct sector-level carbon mitigation policies.

In the present study, oxido-reductive degradation of diazo dye, Direct Red 23, has been carried out by Ziziphus mauritiana peroxidases (specific activity 17.6 U mg⁻¹). Peroxidases have been immobilized via simple adsorption and cross-linking by glutaraldehyde; adsorbed and cross-linked enzyme retained 94.28% and 91.23% of original activity, respectively. The stability of peroxidases was enhanced significantly upon immobilization; a marked widening in both pH and temperature activity profiles were observed. Adsorbed peroxidases exhibited similar pH and temperature optima as reported for the free enzyme. Thermal stability was significantly enhanced in case of cross-linked enzyme which showed 80.52% activity even after 2 h of incubation at 60 °C. Packed bed reactors containing adsorbed and cross-linked peroxidases were run over a period of 4 weeks; adsorbed peroxidases retained 52.86% activity whereas cross-linked peroxidases maintained over 77% dye decolorization ability at the end of the fourth week of its continuous operation. Gas chromatography coupled with mass spectrometry was used to analyze the degradation products; it showed the presence of four major metabolites. Degradation of dye starts with the 1-Hydroxybenzotriazole radical attack on the carbon atom of the phenolic ring bearing azo linkage, converting it into cation radical which underwent nucleophilic attack by a water molecule and results in cleavage of chromophore via symmetric and asymmetric cleavage pathways. Intermediates undergo spontaneous removal of nitrogen, deamination, and oxidation reactions to produce maleic acid as the final degradation product. Graphical abstract

Atmospheric particulate matter (APM) is temporarily settled on the leaf surface of plants and will return to the air via the resuspension process under certain meteorological conditions. How leaf surface characteristics affect the resuspension of settled APM on the leaf surface has been rarely studied. Therefore, the resuspension of APM after settling on plant leaves was analyzed using four common urban greening species, including Prunus triloba, Platanus acerifolia, Lonicera maackii, and Cercis chinensis. The results show that the leaf hair density has a significantly positive correlation with the maximum particulate matter (PM) retention and natural PM retention (p < 0.05). Under the same wind speed, the proportions of the resuspended PM that settled on the leaf surfaces of the four plant species increase with the wind blowing time. During the same wind blowing time, the resuspension rate of the settled PM on leaf surfaces of P. triloba, P. acerifolia, and L. maackii increase with the wind speed. The leaf hair and stomatal density is negatively correlated to the resuspension rate of PM under the wind speed of 1 m s⁻¹ (p < 0.05), and the stomatal density is also negatively correlated to the resuspension rate of PM under the wind speed of 5 m s⁻¹ for 10 min or 20 min (p < 0.05). However, as the wind speed further increase, the leaf characteristics are no longer correlated to the resuspension rate of PM (p > 0.05). These results indicate that when the wind force (wind speed + wind blowing time) is small, the stomatal density and leaf hair density have a significant effect on APM resuspension. When the wind force is large, the influence of leaf surface structure on APM resuspension becomes less profound. APM resuspension is comprehensively affected by the external wind and the leaf surface characteristics, and these two factors jointly determine the fate of the PM after it settles on leaves.