This work is scrutinizing the development of metallized biochar as a low-cost bio-sorbent for low temperature CO₂ capture with high adsorption capacity. Accordingly, single-step pyrolysis process was carried out in order to synthesize biochar from rambutan peel (RP) at different temperatures. The biochar product was then subjected to wet impregnation with several magnesium salts including magnesium nitrate, magnesium sulphate, magnesium chloride and magnesium acetate which then subsequently heat-treated with N₂. The impregnation of magnesium into the biochar structure improved the CO₂ capture performance in the sequence of magnesium nitrate > magnesium sulphate > magnesium chloride > magnesium acetate. There is an enhancement in CO₂ adsorption capacity of metallized biochar (76.80 mg g⁻¹) compare with pristine biochar (68.74 mg g⁻¹). It can be justified by the synergetic influences of physicochemical characteristics. Gas selectivity study verified the high affinity of biochar for CO₂ capture compared with other gases such as air, methane, and nitrogen. This investigation also revealed a stable performance of the metallized biochar in 25 cycles of CO₂ adsorption and desorption. Avrami kinetic model accurately predicted the dynamic CO₂ adsorption performance for pristine and metallized biochar.

The potential of cassava (Manihot esculenta Crantz.) for simultaneous Hg and Au phytoextraction was explored by investigating Hg and Au localization in cassava roots through Micro-Proton Induced X-Ray Emission, High-Resolution Transmission Electron Microscopy (HR-TEM) and X-Ray Diffractometry (XRD). The effect of Hg and Au in the cyanogenic glucoside linamarin distribution was also investigated using Matrix Assisted Laser Desorption Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (MALDI-FT-ICR-MS) imaging. Hg was located mainly in the root vascular bundle of plants grown in 50 or 100 μmol L⁻¹ Hg solutions. Au was localized in the epidermis and cortex or in the epidermis and endodermis for 50 and 100 μmol L⁻¹ Au solutions, respectively. For 50 μmol L⁻¹ solutions of both Hg and Au, the two metals were co-localized in the epidermis. When the Hg concentrations were increased to 100 μmol L⁻¹, Au was still localized to a considerable extent in the epidermis while Hg was located in all root parts. HR-TEM and XRD revealed that Au nanoparticles were formed in cassava roots. MALDI-FT-ICR-MS imaging showed linamarin distribution in the roots of control and plants and metal-exposed plants thus suggesting that linamarin might be involved in Hg and Au uptake and distribution.

Pollution haven hypothesis (PHH) has been investigated extensively in the existing literature due to global environmental issues such as global warming and climate change. However, there is still no consensus on whether this hypothesis is valid. Therefore, the aim of this study is to examine the validity of the PHH in ASEAN-5 countries (Indonesia, Malaysia, Philippines, Singapore, and Thailand) covering the period of 1981–2014. It is utilized the up-to-date panel data techniques taking cross-sectional dependence and slope heterogeneity into account to test the relationship. According to the results of CCEMG and AMG estimators, the validity of the PHH is confirmed in ASEAN-5 countries. The increase in foreign direct investments (FDI) increases environmental degradation in these countries. Our additional findings show that the environmental Kuznets curve (EKC) hypothesis (EKC) is also valid in these countries. There is an inverted U shape between economic growth and CO2 emissions. In addition, energy consumption exacerbates CO2 emissions.

A novel bioflocculant (BW-P3) was produced by a strain of Enterobacter sp. P3 using brewery wastewater as substrate and was further applied to remove the colored substance of fracturing flowback water. The optimum conditions for bioflocculant production were specified by the response surface methodology as COD of brewery wastewater 1487.77 mg/L, glucose 8.94 g/L and initial pH 7.09, under which a bioflocculant yield of 1.274 g/L could be reached. The BW-P3 consists of 79.12% polysaccharides and 15.63% protein. Results show that BW-P3 has a high molecular weight (921 kDa) and contains functional groups (hydroxyl, amino, carbonyl, and acylamino) that likely contribute to flocculation. When using the BW-P3 to flocculate fracturing flowback water, the optimal dosage was 1 g/L BW-P3 with addition of 100 mg/L polymeric aluminum chloride as coagulant aid, and treated under 50 °C at pH 7. Under the optimal condition, the removal rates of chroma and suspended solids (SS) of the fracturing flowback water could reach 85% and 52%, respectively.

Organic waste products (OWP) application to crop lands makes possible nutrients recycling. However, it can result in long-term accumulation of trace elements (TE) in soils. The present study aimed at (i) assessing the impact of regular applications of urban composts and manure on the TE contents of topsoils and crops in a long-term field experiment, (ii) comparing the TE mass balances with the stock variations of TE in soils, and (iii) proposing a prospective evaluation of this practice, based on estimated soil safe threshold values and simulations of soil TE accumulation for 100 years. In the long-term field experiment, physico-chemical properties and TE contents (Cd, Cr, Cu, Hg, Ni, Pb and Zn) have been measured in OWP, soils, plants and leaching waters for the period 1998–2015, and used for mass balance calculations and long-term simulations of TE accumulations. The composts of green wastes and sludge (GWS) and of municipal solid waste (MSW) were the OWP with the largest TE contents, while the farmyard manure tended to have the lowest. Repeated application of OWP led to significant accumulation of Zn and Cu in the topsoil layer (not for Cr, Cd, Hg, Ni, Pb), especially with GWS, without overpassing calculated protective threshold values. No effect of repeated application of OWP has been observed on TE contents in grains (wheat, maize, barley). The positive mass balance has been dominated by the input flux of TE through OWP and resulted in the observed increases of soil stocks for Cu and Zn. Prospective simulation of soil content evolution until 2100 showed that soil content reached 0.4 mg Cd kg⁻¹ soil (GWS, MSW), 38 mg Cu kg⁻¹ soil (GWS) and 109 mg Zn kg⁻¹ soil (GWS), which remained lower than protective threshold values.

A total of 161 water samples were collected from five large and medium-sized city rivers and residential tap waters, Xi’an and Yan’an in Shaanxi province, Xining in Qinghai province, Lanzhou in Gansu, and Urumqi in Xinjiang province, within arid and semi-arid area (NW China). The pH, EC parameters, and concentrations of 10 major ions (F⁻, Cl⁻, HCO₃⁻, NO₃⁻, SO₄²⁻, NH₄⁺, K⁺, Na⁺, Mg²⁺, Ca²⁺) in the drinking waters (DWs) and surface waters (SWs) were analyzed to determine the ion chemistry, geochemical process, and potential anthropogenic input sources and to assess the water quality for drinking, domestic, and irrigation purposes. Durove diagrams and Gibbs diagram indicated that the ions Ca²⁺ and HCO₃⁻ dominant in DWs from Xi’an and Xining were of Ca²⁺-(HCO₃⁻ + SO₄²⁻) type, while sulfate and Na⁺ dominant in SWs, and Na⁺/K⁺-SO₄²⁻ type was for Yan River in Yan’an and Peaceful Canal in Urumqi, their water chemistry influenced by evaporation and rock dominance, and evaporation and fractional crystallization, respectively. Meanwhile, Na⁺/K⁺/Ca²⁺-HCO₃⁻/SO₄²⁻ type dominated in Huang River in Xining and Yellow River in Lanzhou, which dominated by rock weathering. The quality assessments showed that in general the drinking waters were suitable for domestic purposes. However, the high values of NO₃⁻ at some sites influenced by agricultural and industrial inputs made it unsafe for drinking and demand detailed regional drinking water investigations. The assessment of SWs showed that the waters from Yan River in Yan’an and Yellow River in Lanzhou and Huang River in Xining would be used for irrigation. However, high values of SAR, Na%, RSC, and EC at sites in Peaceful Canal restricted suitability for irrigation, and not recommended for drinking water sources. It was noted that for the sustainable development of surface water, a reduction of discharge water from human activities and/or an increase in the fresh water inflow to the surface were needed.

Many studies have highlighted the link between indoor air pollution from the burning of solid fuels for cooking and heating and the occurrence of various health problems particularly in women and children under 5 years. In developing countries, solid fuels remain the main sources of energy. The purpose of this study aims to describe the distribution of household cooking fuel types and to analyze the factors influencing household cooking energy choice in Ouagadougou. A cross-sectional survey was conducted in 2017 in 3 neighborhoods of Ouagadougou. A total of 1734 household were randomly selected. We performed a multivariable logistic regression and a multinomial logistic regression to measure the relationship between selected determinants and households’ primary cooking fuel. 59.53% of the households of Ouagadougou reported using solid fuels as the main cooking fuel. Wood is the most common primary cooking fuel used (43.93%), followed by LPG (40.41%) and then charcoal (15.60%). About 84% combine at least 2 types of energy for cooking. Cooking fuel choice is strongly influenced by the socioeconomic status, the family size, and also by the woman’s educational attainment, her age and the main cooking fuel used in her parents’ house. Actions aimed at reducing the impact of solid fuel use in the environment or health must consider these factors.

Tritium (³H) is a radioactive isotope of hydrogen. In the environment, the most common form of tritium is tritiated water (HTO). However, tritium can also be incorporated into organic molecules, forming organically bound tritium (OBT). The present study characterized the effects of tritium on the health of the fathead minnow, Pimephales promelas. Fish were exposed to a gradient of HTO (activity concentrations of 12,000, 25,000, and 180,000 Bq/L) and OBT using food spiked with tritiated amino acids (OBT only, with an activity concentration of 27,000 Bq/L). A combined exposure condition where fish were placed in 25,000 Bq/L water and received OBT through feed was also studied. Fish were exposed for 60 days, followed by a 60-day depuration period. A battery of health biomarkers were measured in fish tissues at seven time points throughout the 120 days required to complete the exposure and depuration phases. HTO and OBT were also measured in fish tissues at the same time points. Results showed effects of increasing tritium activity concentrations in water after 60 days of exposure. The internal dose rates of tritium, estimated from the tissue free-water tritium (TFWT) and OBT activity concentrations, reached a maximum of 0.65 μGy/h, which is relatively low considering background levels. No effects were observed on survival, fish condition, and metabolic indices (gonado-, hepato-, and spleno-somatic indexes (GSI, HSI, SSI), RNA/DNA and proteins/DNA ratios). Multivariate analyses showed that several biomarkers (DNA damages, micronucleus frequency, brain acetylcholinesterase, lysosomal membrane integrity, phagocytosis activity, and reactive oxygen species production) were exclusively correlated with fish tritium internal dose rate, showing that tritium induced genotoxicity, as well as neural and immune responses. The results were compared with another study on the same fish species where fish were exposed to tritium and other contaminants in natural environments. Together with the field study, the present work provides useful data to identify biomarkers for tritium exposure and better understand modes of action of tritium on the fathead minnow.

The epigenetic changes induced by environmental contaminants play important roles in the inheritance of male reproductive dysfunction. The present study investigated DNA methylation changes and some oxidative stress biomarkers induced by bisphenol A (BPA) in male offspring. A total number of 48 female albino rats were administered orally with 50 μg/kg of BPA/day during gestation and/or lactation periods. At postnatal day 60, the samples were collected from the male pups to assess the serum testosterone, malondialdehyde (MDA) level, superoxide dismutase (SOD), glutathione S-transferase, and glutathione peroxidase (GSH-Px) activities in testicular tissue. DNA methylation in both DNA (cytosine-5)-methyltransferase 3A and estrogen receptor alpha genes was detected by methylation-specific PCR. BPA exposure resulted in significant decrease in the anogenital distance, testis and epididymis weights, serum testosterone level, SOD, GST, and GSH-Px levels with significant increase in weaning body weight and the MDA level. Additionally, BPA caused marked hypermethylation within Dnmt3A and ER- ∝ genes promoter regions in the testis of rat male pups. Graphical abstract

Natural halloysite nanotubes (HNTs) with a hollow lumen have been widely applied in many fields, such as water purification, drug carriers, cosmetics, antibacterial, and scaffolds for tissue engineering. However, their in vivo toxicity is still largely unclear. The aim of this study is to evaluate sub-chronic oral toxicity of HNTs in the small intestine of mice. The results demonstrated that oral HNTs at low dose (5 mg/kg) for 30 days promoted mouse growth with no obvious adverse effect on the small intestine. The promotive effect on mouse growth disappeared after cessation of oral administration of HNTs. Oral HNTs at high dose (50 mg/kg) for 30 days induced aluminum (Al) and silicon (Si) accumulation and oxidative stress in the small intestine, which caused significant increases in the levels of cyclooxygenase-2 (COX-2) and nitric oxide synthase (iNOS) and inflammatory response and iNOS-mediated damages in the organ. Oral HNTs-induced changes in the small intestine at high dose were not observed after a 30-day recovery period. These findings provided the first evidence that oral HNTs-induced sub-chronic toxicity in the small intestine was reversible. The results suggest that HNTs at low concentration in environments have no adverse effect on mice, while there are health risks to mice under severe contamination by HNTs.