The related literature reveal that the papers on environmental pollution do not sufficiently analyse the cement production which is an important determinant of air pollution and health problems by using econometric methods. To fill this gap, this paper aims to examine the relationship between cement production, air pollution, mortality rate, and economic growth by employing MS Bayesian Vector Autoregressive (MScBVAR) and Markov Switching Bayesian Granger causality (MScBGC) approaches from 1960 to 2017 for China, Brazil, India, Turkey and the USA. MSIA(2)-BVAR(1) model for China, MSIAH(2)-BVAR(3) models for India, MSIAH(3)-BVAR(2) for Brazil, and MSIAH(3)-BVAR(1) for Turkey, and MSIAH(2)-BVAR(2) for the USA were selected. The MScBGC results revealed that the cement production is granger cause of mortality rate, air pollution, and economic growth in all regimes for China, India, Brazil, Turkey, and the USA.

This study assessed the polychlorinated biphenyl (PCB) levels in human milk and its associated health risk to infants from rural and urban settings of five districts of Punjab Province, Pakistan. The ∑₃₄PCB concentrations ranged from 30.9 to 68.3 ng g⁻¹ on lipid weight (l.w.) basis. The ∑₈DL-PCB concentrations were ranged from 0.29 to 1.35 ng g⁻¹ l.w., (mean 6.2 ± 8.7 ng g⁻¹ l.w.), with toxicity equivalent to polychlorinated dibenzodioxins (PCDDs) ranging from 8.58 × 10⁻⁶ to 0.05 ng TEQ g⁻¹ l.w. The spatial trend of PCB levels in human milk revealed higher bioaccumulative levels for urban mothers as compared with rural counterparts. The estimated daily intake (EDI) values of DL-PCBs to infants through trans-mammary transfer were considerably higher than tolerable daily intake limits established by WHO (i.e., 1–4 pg TEQ kg⁻¹ bw) and other globally recognized organizations. Similarly, the hazard quotient values for TEQ ∑₈DL-PCBs (range 1.21 to 79.87) were far above the benchmark value of 1 at all the sampling sites, indicating the high levels of adverse health risks to infants in the region through breast milk consumption. The ∑₃₄PCB levels were found to be negatively correlated with mother’ age (r = −0.31; p = 0.02), parity (r = − 0.85; p = 0.001), and infant’ birth weight (r = − 0.73; p = 0.01). The present study suggests undertaking comprehensive public health risk assessment studies and firm regulatory measures to safeguard human health risks.

A submerged anaerobic membrane bioreactor (SAnMBR) was used to treat low-concentration domestic sewage. The effects of hydraulic retention time (HRT) and organic load (OLR) on chemical oxygen demand (COD) removal, methanogenesis, and membrane fouling of the system were investigated. The SAnMBR achieved good COD removal efficiency as well as stable methane production, which were significantly affected by both OLR and HRT. The influent dissolved organic matter (DOM) was decomposed and transformed over time, and DOM concentration was gradually reduced. It can be inferred that the SAnMBR can effectively intercept the production of extracellular polymeric substances and improve effluent quality. The phenomenon of membrane fouling was investigated using various analytical tools. Results demonstrated that the SAnMBR was achieved good transmembrane pressures (TMP) (10–15 kPa), and the hydraulic force generated by the stirring device has a dynamic physical shearing action on the surface of the membrane, which can partly alleviate membrane fouling.

The occurrence and contamination level of seven important toxic metals (Cd, Cu, Co, Cr, Hg, Pb, and Zn) and three additional metals (Al, Fe, and Mn) in the water, sediment, and shrimp muscle in aquaculture areas located in Central Java, Indonesia, were investigated. The results suggest that the majority of metals have higher concentrations in the inlet followed by the outlet and ponds. Cd dissolved in the waters exhibited the highest level in Pekalongan (3.15 ± 0.33 μg L⁻¹). Although Pb was not detected in the water, it was detected in the sediment, and the concentration ranged from 7.6 to 15.40 mg kg⁻¹ dw. In general, the heavy metal concentrations in the sediments were found to decrease in the sequence Al > Fe > Mn > Zn > Cr > Cu > Co > Pb. Concentrations below the effects range low level based on the Canadian sediment quality guidelines were found for Cr, Cu, Pb, and Zn, whereas moderate sediment pollution (25–75 mg kg⁻¹ dw) was observed for Cr (all regions), Cu (except in the Pekalongan region), and Zn (Brebes and Tegal regions) according to the US EPA standard. The status of the waters was evaluated by calculating a pollution index derived mostly from Mn and Zn. The ecological risk (geoaccumulation index (Igₑₒ), contamination factor (CF), pollution load index (PLI), and potential ecological risk index (ERI)) determined in the sediments indicated that all studied areas had low to moderate contamination. The concentrations of all metals in shrimp were generally below the maximum limits for seafood, except for Zn (in all stations), Pb, and Cr (Tegal and Pekalongan). The hazard index values for metals indicated that consuming shrimp would not have adverse effects on human health.

Heavy metals in food are non-intentional pollutants such as lead (Pb), cadmium (Cd), and mercury (Hg). Pb, a neurotoxic substance, is classified as a possible carcinogen for humans (group 2B) by the International Agency for Research on Cancer (IARC) under the World Health Organization (WHO). Cd, a substance that causes kidney damage, is classified as a substance that causes human cancer (group 1). In this study, inductively coupled plasma atomic emission spectrometry (ICP-AES) and a mercury analyzer (MA) were used to identify the concentrations of heavy metals (Pb, Cd, Hg) in fishery products and to assess the effects of chronic human exposure to heavy metals via fisheries consumption. Food consumption data were obtained from the Korea National Health and Nutrition Examination Survey (KNHANES 2010–2015), and the mean exposure concentrations for Pb, Cd, and Hg were 0.0067 μg/kg bw/day, 1.1277 μg/kg bw/month, and 0.0872 μg/kg bw/week, respectively. Exposures to Pb, Cd, and Hg using the 95th percentile of the consumption data were 0.0183 μg/kg bw/day, 4.0230 μg/kg bw/month, and 0.2268 μg/kg bw/week, respectively, corresponding to 3, 16, and 6% of the human exposure safety standard. Safe guidelines for the intake of fishery products are proposed to reduce the exposure to and accumulation of heavy metals in humans.

This paper illustrates the direct and indirect effects of democracy on CO₂ emissions in the BRICS countries (Brazil, Russia, India, China, and South Africa) from 1992 to 2018. In view of the distribution heterogeneity of CO₂ emissions, the panel quantile regression model is especially used to explore the nexus among different variables. Furthermore, in order to predict the trends of CO₂ emissions in different countries, we also estimate the kernel density function of CO₂ emissions in the BRICS countries by the quantile-fitted values. The results indicate that the direct impact of democracy on carbon dioxide emissions is significantly negative and great at high-emission countries. Although the indirect effect of democracy is positive in China and negative in Brazil and South Africa, the total effect of democracy on CO₂ emissions remains negative in all BRICS countries. The estimation of kernel density function shows that the distribution of CO₂ emissions in each country is gradually concentrated. Moreover, there is an environmental Kuznets curve depicting the linkage of urbanization and carbon dioxide emissions in Brazil and South Africa. These findings further highlight that the impact of democracy on high-emission and low-emission countries should be taken into account in policymaking to achieve sustainable developments.

To investigate the variation of the biogeochemical cycle of riverine dissolved inorganic carbon (DIC) and silicon (DSi) with the cascade damming, the bicarbonate ([Formula: see text]), dissolved silicon (DSi), and other environmental factors within the cascade reservoirs of the lower reaches of Yalongjiang River, passing through the southeastern Qinghai-Tibet Plateau, were systematically analyzed by collecting water samples during the wet season and dry season from 2018 to 2019, respectively. The results showed that the lower ratio of DSi to[Formula: see text] (0.044 ± 0.001) was mainly controlled by the domination of carbonate mineral in the sedimentary rock of the Yalongjiang River drainage basin. The DSi:[Formula: see text] ratio was positively correlated with discharge (P < 0.05), and negatively correlated with the water retention time (P < 0.01) and chlorophyll a, implying that the variations of DSi:[Formula: see text] ratio were mainly determined by the rock chemical weathering processes and the hydrologic process outside the reservoirs and the biological processes within the cascade reservoirs. The phytoplankton photosynthetic process stoichiometrically assimilated DSi and [Formula: see text], resulted in 3.46 × 10⁴ t·Si a⁻¹ and 1.89 × 10⁴ t·C a⁻¹ sequestering in the cascade reservoirs, respectively. Compared with the situation of dam-free in the lower reaches of Yalongjiang River, the export flux of [Formula: see text] and DSi at the mouth of Yalongjiang River was reduced by 11.87% and 62.50%, respectively; the ratio of DSi:[Formula: see text] decreased by 36.01% for only building the Ertan dam and 53.15% for the cascade damming, respectively. The water renewal time prolonged from 45 to 126.6 days due to the regulation of the cascade reservoirs in the mainstream. Ultimately, a conceptual model on migration-transformation of DIC and DSi within the cascade reservoirs in the lower reaches of Yalongjiang River was established. These findings demonstrated that riverine cascade damming could extend the biogeochemical coupling cycle of DIC and DSi within the inland aquatic ecosystems and ensure the ecological environment security in the hot-dry valley.

This paper investigates the dynamic short-term and long-term relationships among per capita GDP, per capita energy consumption, per capita renewable energy consumption, trade openness, and per capita carbon dioxide (CO₂) emissions within the framework of the environmental Kuznets curve (EKC) hypothesis for Korea from 1971 to 2017. According to the empirical findings of the autoregressive distributed lag (ARDL) bounds testing procedure, although increases in per capita GDP and per capita energy consumption increase per capita CO₂ emissions, per capita renewable energy consumption and trade openness decrease per capita CO₂ emissions. Furthermore, according to the empirical results, an N-shaped relationship has been identified between per capita CO₂ emissions and per capita GDP. This indicates that our empirical findings do not support the EKC hypothesis in Korea. Thus, economic growth alone is not sufficient to address environmental pollution; in response, active environmentally friendly policies should be implemented, and the energy matrix should be transformed in favor of renewable energy in Korea.

This study investigates the transmission of volatility between OPEC-oil and sector stock returns in Pakistan. The issue of volatility spillovers across the oil and sector stocks is a crucial part of risk management and portfolio designs, as all firms are not expecting to be equally affected by changes in oil price. Empirically, we estimate a bivariate VAR-GARCH model using daily data sampled from January 1, 2003 to December 29, 2017. We also analyze the optimal weights and hedge ratios for oil-stock portfolio holdings based on our model results. Our findings reveal that negative and significant spillover effects from the oil market to agriculture, energy, and machinery sector stocks are present. However, our findings show that volatility spillover effects are insignificant from stock returns to oil. The findings of the study illustrate that development of stock market will motivate highly polluting firms to invest more in renewable and clean energy, which will help reduce carbon emissions.

Diatomite is an economical and environmentally friendly adsorbent, and its use has been applied widely for the treatment of water contaminated by heavy metals. Despite this, the mechanism for the removal of the heavy metal Cd(II) remains unclear. In this work, we explored the adsorption mechanism of Cd(II) by diatomite using batch experiment, and characterized the diatomite using scanning electron microscopy, energy-dispersive spectrometry, specific surface area, and pore size distribution analysis. Our results showed that, under the experimental conditions, the kinetic adsorption approached equilibrium within 5 min, and the Sips isotherm model was most suitable for data fitting. EDS characterization of the Cd-loaded diatomite indicated that Cd(II) was adsorbed onto the diatomite. Furthermore, desorption experiments showed that Ca²⁺ and Mg²⁺ in the diatomite caused an ion exchange interaction, and this was primarily responsible for Cd(II) adsorption. Moreover, we found that its contribution to the whole adsorption reaction could reach 80%, while the remainder of Cd(II) was probably trapped in the microporous structure of the diatomite. Additionally, our data indicated that the adsorption mechanism did not change significantly after regeneration. These results have provided special insight into the deep understanding of the mechanism of Cd(II) adsorption by diatomite, and could provide theoretical support and guidance for further development and application of diatomite in the treatment of Cd(II)-contaminated water. Graphical abstract