Three sequential extraction procedures (SEPs), modified Tessier, modified BCR, and CIEMAT, were compared for mercury fractionation in polluted soils. With satisfactory total mercury recovery, the modified Tessier and modified BCR SEPs were comparable with each other in terms of extraction efficiency in equivalent mercury fractions, whereas both SEPs were not as efficient as the CIEMAT SEP. However, the CIEMAT SEP might underestimate the oxidizable mercury fractions due to the humic and fulvic complexes instead of the organic matter of the other two SEPs. For mercury bioavailability identification, based on Pearson correlation analysis, all fractions in each SEP were significantly correlated with mercury uptake in Ipomoea aquatica, causing difficulty in comparison. Partial correlation analysis indicated that the mobile mercury fractions extracted by the first step in all three SEPs had a positive correlation with mercury uptake by plant, while mercury bound to organic matter extracted by both modified Tessier and modified BCR SEPs presented negative correlation with mercury uptake by plant which was in contrast to CIEMAT SEP. Meanwhile, clearly positive correlations between mercury fractions extracted by the former three steps of CIEMAT SEP and mercury uptake in Ipomoea aquatica were observed, demonstrating that CIEMAT SEP provided more accurate results related to Hg bioavailability than did the other two SEPs.

Formation dip angle and the distortion of salinity affect the spatial distribution and storage capacity of carbon dioxide (CO₂). In this numerical study, based on an actual CO₂ injection demonstration project (Shiqianfeng group in the Ordos Basin) in China, CO₂ was injected for a period of 20 years at four different formation dip angles (0°, 5°, 10°, 15°). In conjunction, some salinity values were chosen, ranging from saturation salinity to no salinity. A three-dimensional (3D) model was established to systematically explore the influence of different formation dip angles and salinities on the CO₂ spatial distribution and storage amount. The simulation results showed that larger salinity and higher pressure near the injection well will lead the CO₂ gas-phase saturation and mass fraction to be smaller for a given formation dip angle. When salinity is held constant at the saturation value, a larger dip angle will cause a smaller CO₂ gas saturation in the upper right units of the injection well, and a larger gas saturation in the lower left units at the 20th year of CO₂ injection. For large salinity values (full, half, and quarter saturation salinity), the larger the formation dip angle is, the greater the CO₂ total storage amount. For smaller salinity values (0.00 and 0.03), a transition point existed (at 8 and 18.2 years) during the 20-year injection period. Before the transition point, the CO₂ total storage amount also increases with the dip angle. After the transition point, however, the larger the formation dip angle is, the smaller the CO₂ total storage amount becomes. In addition, a lower salinity may lead to the earlier appearance of the transition point.

Temperature is associated with mortality risk across cities. However, there is lack of study investigating the summer effect on mortality associated with mental/behavioral disorders, especially in cities with subtropical climate. In addition, summer mortality in subtropical cities is different from tropical cities, and previous studies have not investigated the urban environmental inequality on heat mortality associated with mental/behavioral disorders. A register-based study was developed to estimate the temperature effects on decedents on days with 50ᵗʰ percentile of average daily temperature between 2007 and 2014 in Hong Kong (n = 133,359). Poisson regression was firstly applied to estimate the incidence rate ratio (IRR) from the summer temperature effects on all-cause mortality, cardiovascular mortality, respiratory mortality, and mortality associated with mental/behavioral disorders. For a 1 °C increase in average temperature on days with temperature ≥ 24.51 °C, IRRs of mortality associated with mental and behavioral disorders on lag 0 and lag 1 days were 1.033 [1.004, 1.062] and 1.030 [1.002, 1.060], while temperature effects on cardiovascular mortality and respiratory mortality during normal summer days (not extreme heat events) were not significant. A further investigation with linear regression has shown that decedents with mental/behavioral disorders on higher temperature days resided in areas with lower percentage of sky view, lower percentage of vegetation cover, higher level of neighborhood-level PM₂.₅, higher level of neighborhood-level NO, and higher level of neighborhood-level black carbon (BC). In order to develop protocols for community healthcare based on the “Leaving no one behind” scheme documented in the 2016 Sustainable Development Goals report of the United Nations, it is necessary to include heat effects on mental/behavioral disorders, especially people with dementia, for community planning and healthcare development.

The Volkswagen scandal has promoted experimental campaigns worldwide aimed to assess the real exhaust emissions of in-use vehicles. Attention has been paid to diesel vehicle NOx emissions that are much higher than legislative type-approval limits. This paper analysed exhaust emissions of a fleet of ten Euro 5 diesel vehicles. NOx emissions were measured during laboratory and track testing. In both cases, the type-approval test was carried out with cold and warm starts. Moreover, in the laboratory, a modified type-approval test and a real urban driving cycle were executed in order to characterise emissions in multiple operating conditions, outside of the homologation boundaries. The testing environment did not influence the emissions behaviour of the tested vehicles. Track and laboratory results, in fact, were comparable when ambient conditions were comparable. The parameter which played the main role in terms of NOx emissions is the ambient temperature, fixed at 23 °C in laboratory and not controlled on the track. Above 28 °C, NOx emissions were much higher than the approval limit (almost 600 mg/km). Moreover, warm driving cycles always introduced higher NOx emissions than cold ones, because of the partial use and/or deactivation of the EGR circuit (one of effective measures to reduce NOx formation). The ratio between warm and cold emissions ranged from 2 to 5. The engine parameter which helped explain the relationship between NOx emissions and thermal engine status was the intake air temperature. For intake air temperatures below 40 °C, NOx emissions were lower than 0.2 g/km. Above 40 °C, they suddenly increased up to almost 0.6 g/km. Another issue highlighted by the experimental results was that dynamic real driving caused the highest NOx emissions (almost 1 g/km).

Microplastics, particles less than 5 mm in size, are an emerging contaminant in waterways worldwide. Most microplastic studies focus on spatial trends in concentration, but in systems as dynamic as rivers, to draw conclusions from existing spatial studies, we must first examine how microplastic concentrations may change with time and flow conditions. In this study, we investigate how microplastic concentrations change over a 24-h period and between seasonally high and low flows. We do this in two streams, controlling for wastewater treatment strategy: one stream in a watershed where waste is treated with septic systems and the other receiving wastewater treatment plant effluent. We hypothesized that a stream with wastewater treatment plant effluent would exhibit higher and more variable microplastic concentrations than a stream in a watershed with septic systems. Results indicate, however, that there is no significant difference between the two streams despite their differing treatment strategies. Additionally, no significant variation in concentrations was measured over two 24-h sampling campaigns. There was, however, significantly higher concentrations measured in summer low flow conditions relative to spring high flow conditions across both sampled streams (p value <0.001), indicating that increases in stream discharge unrelated to storm events dilute and decrease measured microplastic concentrations. From this, we learn that pairing measured concentrations with a description of flow conditions at sampling time is a requisite for a robust microplastic literature that allows for comparisons between existing spatial studies and extrapolations to global loads.

By a simple and convenient method of using epichlorohydrin as linkages, a novel Alternanthera philoxeroides (AP) derivative modified with diethylenetriamine (DAP) was synthesized, which can remove copper(II) ions (Cu(II)) in the water environment efficiently. The adsorption capacity of DAP for Cu(II) under various factors was measured using ultraviolet spectrophotometer. The adsorption capacity and removal ratio were 19.33 mg/g and 95.57% at pH 5.5 and 298 K. The kinetic and equilibrium study shows that pseudo-second-order kinetic (R² = 0.9964) and Langmuir isotherm models (R² > 0.982) could properly describe DAP adsorption behaviors, and thermodynamic parameters indicate a spontaneous endothermic process (ΔG = − 3.6636 kJ/mol). The combined results of SEM, XRD, FTIR, and XPS analyses reveal that the dominant contribution for enhancement in Cu(II) adsorption is made by the formation of an amino group. And the adsorption mechanism is mainly the complexation reaction. The adsorption efficiency of DAP remained above 72.06% after 6 cycles of adsorption-desorption, which indicated that DAP has good regenerability and stability. All the results suggest that DAP could serve as promising adsorbents for Cu(II) pollution minimization.

A gradual increase in the importance of water environment infrastructure has provided an opportunity to bring in various initiatives for the supply of sewage. Such initiatives include the dissemination of public sewage systems and the use of subcontractors in management of sewage systems. However, despite the existence of various methods to increase the rate of sewage supply, there are few studies analyzing each alternative in terms of social, economic, and environmental aspects. Therefore, we investigated investment directions for water environment infrastructure facilities related to the supply of sewage treatment systems in rural areas through cost-benefit analysis. We analyzed the economic costs and social benefits of two sewage treatment systems: installation of a public sewage treatment system and utilization of a private sewage treatment system via service contract. When we considered only economic costs and benefits, the benefit-cost ratio for the public system (0.02) was smaller than that for the private system (0.264). However, the results of the two alternatives changed when we considered the social benefits to people in urban areas from establishment of public sewage treatment systems in rural areas. To be specific, by considering the social benefits for non-rural areas, this study found that the benefit-cost ratio for the public system increased to 0.267, which was higher than the ratio for the private system. Based on these results, we propose appropriate operations and management plans for supplying sewage treatment systems to rural areas. Further, this study indicates that policymakers who conduct cost-benefit analyses of infrastructure related to water environments should consider all social, environmental, and economic factors that can alter the analysis results.

Bisphenol A (BPA), diethyl phthalate (DEP), and carbamazepine (CBZ) have been widely used in chemical and pharmaceutical fields, and their residues are detected in various environments. Therefore, to find a suitable method for removing the compounds from an aqueous solution, an adsorption method by granular activated charcoal (AC) was studied. To investigate the adsorption properties of AC, its kinetics, equilibrium, pH effects, and regeneration of AC were examined. Moreover, its surface properties (i.e., surface area, pore volume, functional groups, and surface charge) were characterized by N₂ adsorption and desorption isotherm, Fourier transform infrared (FTIR), and zeta potential analyses. Experimental results show that AC has high removal efficiencies for the target compounds at the low initial concentration as well as high estimated adsorption capacities (qₘ) for DEP, BPA, and CBZ, whose values were 293.4 ± 18.8, 254.9 ± 16.2, and 153.3 ± 1.61 mg/g, respectively. In comparison with other adsorbents based on previously reported results, AC was shown to have generally higher removability for the three compounds than others. Moreover, it was observed that AC’s ability to adsorb DEP and BPA was dependent on pH because of hydrolysis and ionization, respectively. Meanwhile, there is no pH effect for CBZ adsorption by AC. After 3 cycles of adsorption/desorption, AC still maintained 92, 100, and 82% of initial adsorption capacities for DEP, BPA, and CBZ, respectively. Therefore, the AC is an effective adsorbent for the removal of endocrine-disrupting chemicals and pharmaceuticals from aqueous solution.

A valuable method for the efficient removal of sulphonamides from wastewater using protein powder extracted from the seeds of Moringa stenopetala is presented in this study. The surface morphology, crystallinity and functional groups of protein powder were characterised by SEM, XRD, FTIR and Raman spectrometry. Parameters that affect the removal of sulphonamides, such as concentration, the adsorbent dosage and pH, were optimised. The method was applied to a real wastewater sample collected from the Daspoort Wastewater Treatment Plant located in Pretoria, South Africa. The percentage removal under optimum conditions was observed to be 86.4 to 95.1% for the aqueous solution of a mixture of standards and from 83.0 to 90.5% and 75.2 to 87.7 % for the effluent and influent wastewater samples respectively. Therefore, proteins extracted from Moringa stenopetala seeds demonstrated to be effective and environmentally friendly material for possible application in water treatment in general and wastewater treatment in particular.

China, the largest developing country, is the world largest cement producer and the largest cement-consuming nation. Although China’s cement output reached its peak in 2014, regions, i.e., Fujian and Yunnan provinces, were no peaking until 2016. At the same time, rare studies referred to China’s cement consumption and CO₂ emissions from the perspective of cement consumption at the provincial level. We developed the S-Logistic, polynomial model, and ARIMA model to study the peaking time of cement consumption at the provincial level, and we also projected China’s cement consumption and CO₂ emissions toward 2030. Meanwhile, the discrepancies of peaking time and cumulative cement consumption per capita (CCCPC) among provinces were also studied based on GDP per capita and urbanization rate (UR). The results are that the CCCPC respectively in the range of 22–34 ton, 18–25 ton, and 17–27 ton in the eastern, intermediate, and western zone when cement consumption reached its peak. We draw the following conclusions that the CCCPC in 2030 could reach ~ 43 ton and the projected cement consumption is ~ 1252.72 Mt, which accounts for 50% of that in 2017, and cement CO₂ emissions are at the range of 488.19–510.90 MtCO₂ in 2030. Furthermore, capacity replacement, controlling new capacity and eliminating backward capacity are significant of greenhouse gas emission reduction not only for China, but also for the global cement industry.