In many parts of the world, groundwater is considered as one of the main sources of urban and rural drinking water. Over the past three decades, the qualitative and quantitative characteristics of aquifers have been negatively affected by different factors such as excessive use of chemical fertilizers in agriculture, indiscreet, and over-exploitation use of groundwater. Therefore, finding the effective method for mapping the water quality index (WQI) is important for locating suitable and non-suitable areas for urban and rural drinking waters. In the present paper, the best method to estimate the spatial distribution of WQI was assessed using the inverse distance weighted, kriging, cokriging, geographically weighted regression (GWR), and hybrid models. Creating hybrid models can increase modeling capabilities. Hybrid methods make use of a combination of estimated model capabilities. In addition, to improve the results of cokriging, GWR, and hybrid methods, the auxiliary parameters of land slope, groundwater table, and groundwater transmissibility were used. In order to assess the proposed methodology, 11 qualitative parameters obtained from 63 observation wells in Marand Plain (Iran) were utilized. Four statistical measures, namely the root mean square error (RMSE), the mean absolute error (MAE), the Akaike coefficient (AIC), and the correlation coefficient (R²) along with the Taylor diagram, have been done. Classification of the WQI index showed that the quality of a number of 1, 27, 18, and 17 wells was, respectively, in excellent, good, moderate, and poor grades. The results of modeling the WQI index based on IDW, kriging, cokriging, GWR, and hybrid methods showed that the best estimate of WQI was obtained by using hybrid GWR-kriging method with three input parameters of land slope, groundwater table, and groundwater transmissibility. Therefore, hybrid kriging and GWR methods have been fairly well able to simulate the WQI index.

A novel assembly method was used to prepare the sulfhydryl functionalized magnetic SBA-15 (SH-M-SBA-15). The physicochemical properties of SH-M-SBA-15 were characterized by TEM, XRD, EDS, FT-IR, BET, and VSM. Batch adsorption experiments were conducted to investigate the influence of initial uranium concentration, dosage of adsorbent, pH values, contact time, and temperature on the adsorption efficiency and behaviors. The adsorption types were analyzed from the aspects of kinetic, isotherms, and thermodynamic. The results show that the specific surface area of SH-M-SBA-15 is 316.67 m²/g, which is smaller than that of SBA-15 (692.18 m²/g). However, compared with SBA-15, SH-M-SBA-15 has more surface sulfhydryl functional groups. The addition of this group can improve the adsorption of uranyl ions by SH-M-SBA-15. The optimal adsorption conditions were adsorption dosage 40 mg/L, pH 6, temperature 35 °C, contact time 180 min, and initial uranium concentration 35 mg/L. Under this condition, the maximum adsorption amount of uranyl ion by SH-M-SBA-15 can reach 804.79 mg/g, which is much higher than the highest adsorption capacity of uranyl ion by SBA-15 (146.23 mg/g). The adsorption process was better depicted by the Langmuir isotherm model. The process was consistent with the quasi-second-order model. ΔG was negative and ΔH was positive, indicating spontaneous and endothermic adsorption.

In recent years, the photocatalytic process by using TiO₂ nanoparticles (NPs) has produced a great interest in wastewater treatment due to its interesting features such as low-cost, environmental compatibility, and especially capacity to eliminate persistent organic compounds as well as microorganisms in water. In the present work, the photocatalytic activity of Gd-doped TiO₂ nanopowders, with different doping amount 0.1, 1, and 5 mol% synthesized by the sol-gel method, was studied under UV/Visible irradiation for water treatment application. The Gd-doped TiO₂ nanoparticles were investigated for their photocatalytic degradation of methylene blue (MB) dye and antibacterial activities against two bacterial strains namely Stenotrophomonas maltophilia (S. maltophilia) and Micrococcus luteus (M. luteus). MB dye was used as a pollutant model to estimate reactive oxygen species (ROS) generation and to correlate killing action of nanoparticles with the generation of ROS. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Raman spectroscopy were used to characterize the as-synthesized nanomaterials. Photocatalytic, as well as antibacterial tests, showed that doping with an appropriate amount of Gd could reduce the radiative recombination process of photogenerated electron-hole pairs in TiO₂ and induce a significant enhancement in photocatalytic and consequently antibacterial activity. The experimental sequence of bactericidal activity and photocatalytic degradation efficiency exhibited by the different gadolinium-doped nanoparticles was the following: 0.1 mol% Gd-doped TiO₂ > 1 mol% Gd-doped TiO₂ > 5 mol% Gd-doped TiO₂ > pure titania.

The linkage between high concentration of greenhouse gases (GHGs) and climate change is well recognized as there is severe influence of climate change on public health. Carbon dioxide is most prominent GHG which deteriorates the environment and impacts human health. On the parallel, economic growth also affects health conditions sometimes positively or vice versa. The objective of this research work is to examine the dynamic linkages among CO₂ emissions, health expenditures, and economic growth in the presence of gross fixed capital formation and per capita trade by using auto regressive distributive lag (ARDL) model for Pakistan covering annual data from the year 1995–2017. Our empirical results show that there is significant long run as well as short-term causal relationship between health expenditure, CO₂ emissions, and economic growth in Pakistan. Bidirectional relationship of Granger causality is found between health expenditures and CO₂ emissions, and further between health expenditures and economic growth. Short-run unidirectional causality is running from carbon emissions to health-related expenditures. The bidirectional causal relationship is also investigated between carbon emissions and growth as well as gross fixed capital formation and growth. Then, policy recommendations towards controlling pollution, particularly CO₂ emissions and health expenditures without compromising economic growth are suggested. Graphical abstract .

The occurrence of persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) in the atmosphere of six sites with different emission sources in the province of Córdoba, Argentina, was analyzed. The sites included urban, industrial, agricultural, and mountain areas. Samples were collected using passive air samplers (PAS) consisting of polyurethane foam disks (PUF). Samples were analyzed for 12 PAHs, 31 polychlorinated biphenyls (PCBs), 12 organochlorine pesticides (OCPs), and 11 polybrominated diphenyl ethers (PBDEs). The concentrations of PAHs in the atmosphere were elevated at urban sites and were even higher at the industrial site. With respect to OCPs, it was observed that the concentrations of endosulfan were greater at the agricultural site (AGR) (416 ± 4 pg m⁻³). For hexachlorocyclohexanes (HCHs), only the alpha isomer was detected and there were minimal differences between the different sampling sites (5.9–13.3 pg m⁻³). In the case of dieldrin, the highest concentrations (33.6 pg m⁻³) were found at the mountain site, which may have been due to its use for insect control. Although heptachlor epoxide was not detected, the concentration of heptachlor was significantly higher at the agricultural and downtown sites (∼ 3.6 pg m⁻³). Regarding DDTs, the isomers p,p′-DDT and p,p′-DDE showed the highest concentrations at the mountain site (ΣDDT 120 ± 12 pg m⁻³) and downtown site (ΣDDT 157 ± 62 pg m⁻³). The relationship between the isomers suggested that at the downtown site, the contribution of this pesticide to the environment was recent, probably for the control of diseases vectors. The congener pattern of PBDEs was dominated by BDE-47, and BDE-99 at all sites, with the downtown site having the highest concentrations of compound esters (ΣPBDEs 118 ± 38 pg m⁻³). Finally, high concentrations of PCBs were found at the industrial site (ΣPCBs 1677 ± 134 pg m⁻³), and the predominating homologs were 5-Cl and 6-Cl, in contrast to the other sites where PCBs were dominated by 3-Cl and 4-Cl. This is the first study of POPs carried out in the province of Córdoba.

Alkali metal chlorides emitted from sintering flue gas are easily adsorbed on the surface of activated carbon (AC) in the purification process. In this paper, NaCl particles adsorbing onto AC were simulated by impregnation method, and the size and morphology of NaCl particles were similar to those of NaCl-PM₁₀ emitted from sintering flue gas. With the adsorption of NaCl particles, 2–10-μm pores of AC were filled, and the specific surface area of AC decreased. But NaCl led to the increase of acidic functional groups on the surface of AC. When 0.75 wt% NaCl was adsorbed, it was beneficial for AC catalytic denitration (de-NOx), because the chemical reaction was strengthened by acidic functional groups, so it showed a certain promotion of de-NOx efficiency. As 1.5 wt% NaCl and 3 wt% NaCl were adsorbed, NaCl had an inhibitory effect on AC de-NOx, which was because the specific surface area of AC decreased, and the prevention of physical adsorption played a major role. As a result, the de-NOx efficiency of AC adsorbed with 3 wt% NaCl decreased from 40.59 to 23.02% at 150 °C. Therefore, the absorption of NaCl fine particles on AC should not exceed 0.75 wt%.

Monitoring the amount and composition of airborne particulate matter (PM) in the urban environment is a crucial aspect to guarantee citizen health. To focus the action of stakeholders in limiting air pollution, fast and highly spatially resolved methods for monitoring PM are required. Recently, the trees’ capability in capturing PM inspired the development of several methods intended to use trees as biomonitors; this results in the potential of having an ultra-spatially resolved network of low-cost PM monitoring stations throughout cities, without the needing of on-site stations. Within this context, we propose a fast and reliable method to qualitatively and quantitatively characterize the PM present in urban air based on the analysis of tree leaves by scanning electron microscopy combined with X-ray spectroscopy (SEM/EDX). We have tested our method in the Real Bosco di Capodimonte urban park (Naples, Italy), by collecting leaves from Quercus ilex trees along transects parallel to the main wind directions. The coarse (PM₁₀–₂.₅) and fine (PM₂.₅) amounts obtained per unit leaf area have been validated by weighting the PM washed from leaves belonging to the same sample sets. PM size distribution and elemental composition match appropriately with the known pollution sources in the sample sites (i.e., traffic and marine aerosol). The proposed methodology will then allow the use of the urban forest as an ultra-spatially resolved PM monitoring network, also supporting the work of urban green planners and stakeholders.

The aim of this review was to investigate the effects of possible harmful waves from either cell phone use or being within the range of the cell phone from 450 to 3800 MHz on the thyroid cells and hormones. Eight electronic datasets were systematically searched using MeSH terms, including “cell phone,” “mobile phone,” “GSM,” “radio frequency,” “smartphone,” “triiodothyronine,” “thyroxin,” “thyroid-stimulating hormone,” “T3,” “T4,” “TSH,” and “morphological” and all possible combinations, to identify relevant studies published up to Dec 2018. We also manually searched the reference lists of potentially selected studies to identify further relevant publications. About 161 relevant studies were initially found. After screening titles and abstracts, 139 studies were excluded, and finally 22 studies (comprising 7182 cases) were included in the qualitative synthesis. Of the 22 included studies, 11 studies reported changes in T3 and T4 levels (six reported a decrease in T3 levels and one reported increase in it); moreover, five found decreased T4 levels and two studies an increased level. In other 10 studies, TSH alteration was reported. Of these, two studies reported a decrease in TSH level and one reported an increase in the hormone levels, while in the remaining studies non-significant changes were reported. Finally, seven studies examined histological changes in the thyroid gland follicles and showed that the volume of these cells was reduced. Based on the evidence discussed above, the reduction in diameter of thyroid follicles is potentially linked with cell phone radiation. Exposure may negatively influence the iodine uptake in the thyroid gland or increases temperature effect on the thyroid gland. However, further research are needed in order to show that the level of TSH and thyroid hormone suppression by microwave.

This paper investigates the impact of tourism investments on energy efficiency across the transportation and residential sectors of 32 Organization for Economic Co-operation and Development economies. Using annual data from 1995 to 2012, we employ various panel econometric techniques to achieve the study objectives. Given the nature of variables, the paper applies panel autoregressive distributed lag models to estimate the long-run elasticities of energy intensity. The long-run estimates confirm that tourism investments play an essential role in improving energy efficiency across the transportation and residential sectors. Furthermore, the results show that both the foreign direct investment inflows and trade openness also play a considerable role in reducing energy uses across these sectors. Finally, the findings suggest that the tourism investments Granger cause energy efficiency of transportation and residential sectors in the short-run. Given these findings, the paper adds considerable value to the empirical literature and also provides various policy- and practical implications.

In this study, greenhouse experiments were conducted under the condition of different amendment ratios and planting tall fescue (Festuca arundinacea). The amendment ratios of sewage sludge or sludge compost to soil were of 0, 10, 25, and 50% (w/w). The removal rates of PAH, catalase, and dehydrogenase activities of amended soil and accumulation of PAHs by vegetation were detected to investigate the differences of PAH dissipation in sludge-amended and compost-amended soils. The initial PAH concentrations in three amended soils increased with the more addition of sludge or compost. After 126-day experiment, maximum PAH removal rates were observed in sludge-amended and compost-amended soils with PAH concentration of about 200 μg kg⁻¹. And the removal of PAHs showed better efficiencies in compost soil rather than in sludge soil. The more catalase activity and dehydrogenase activity of soil were obtained, respectively, in sludge soil and compost soil. The results indicated that the mechanism of PAH dissipation in two types of amended soils were different. The abundant amount of microorganism dominated PAH dissipation in sludge soils, and PAHs dissipated mainly caused of intense activity of microorganism in compost soils. In addition, PAH accumulation in tall fescue suggested that the transference approach of PAHs was from soil to the roots, and then accumulated in the shoots of tall fescue. It was prone to store up more PAHs in vegetation in the condition of high molar weight of PAHs, more biomass of vegetation, and heavy PAH concentration in soil.