This study reports the preparation of highly dispersed nanoscale zerovalent iron (nZVI) with core-shell structure decorated onto graphene nanosheets (Gr-NS) to form nZVI-Gr-NS composite. Meanwhile, its excellent performance for concentrated Zn(II) wastewater treatment is also studied. The adsorption of Zn(II) onto nZVI-Gr-NS is well simulated by the pseudo-second-order model, which indicates the adsorption is the rate-controlling step. Moreover, the adsorption isotherms of Zn(II) on the nZVI-Gr-NS can fit well with the Langmuir model. The negative thermodynamic parameters (△GƟ, △HƟ, △SƟ) calculated from the temperature-dependent isotherms indicate that the sorption reaction of Zn(II) is an exothermic and spontaneous process. The high saturation magnetization (37.4 emu g⁻¹) of the nZVI-Gr-NS makes separation of nZVI-Gr-NS-bound Zn(II) easily and quickly from aqueous solution. Most importantly, nZVI-Gr-NS composites not only remove Zn(II) but also spontaneously remove As, Se, and Cu ions from real smelting wastewater samples. This study provides a good solution for heavy metal removal in real wastewater.

Cross-sectional data (N = 25427) from the National Health and Nutrition Examination Survey for 2003–2014 for US adults were used to estimate the impact of co-exposure to high levels of cadmium, lead, and mercury on the unhealthy kidney function. If observed concentrations of cadmium, lead, and total mercury were above the 75th percentile of their respective distributions, the exposure to the corresponding metal was considered to be high. Logistic regression models were fitted to estimate the probabilities of an unhealthy kidney function. Two alternate definitions of unhealthy kidney function were used. First, if estimated, glomerular filtration rate (eGFR) was < 60 mL/min/1.73 m² (KₑGFR) and second, if the observed albumin creatinine ratio (ACR) was ≥ 30 mg/g creatinine (KACR). As compared with low exposures, adjusted odds ratios (AOR) for unhealthy kidney function when exposed to high levels of lead and cadmium were observed to be 1.567 (1.346–1.823) and 1.663 (1.376–2.010) respectively for KₑGFR. When exposed to high levels of both cadmium and lead, AORs for unhealthy kidney functions KₑGFR and KARC were found to be 2.369 (1.868–3.004) and 1.522 (1.216–1.905) respectively. When exposed to high levels of cadmium, lead, and mercury, AORs for unhealthy kidney functions KₑGFR and KARC were found to be 2.248 (1.428–3.538) and 1.502 (1.024–2.204) respectively. High exposure to lead along with any level of exposure to cadmium and total mercury was found to adversely affect the health of kidney function. High exposure to mercury does not affect unhealthy kidney function.

Cassia fistula L. (Caesalpinioideae) is a highly admirable medicinal plant and is traditionally recommended for the treatment of rheumatism, liver disorders, jaundice, and other inflammatory diseases. This study was designed to investigate the hepatoprotective properties of ethyl acetate fraction from C. fistula leaves in an animal model. Treatment with thioacetamide significantly elevated the level of serum glutamic-oxaloacetic transaminase (1.75-fold), alkaline phosphatase (4.07-fold), and total bilirubin (2.29-fold) as compared to the control. It was found that pretreatment of fraction followed by consecutive 2 days thioacetamide reduced the conversion of thioacetamide carcinogen to its reactive metabolites by phase I enzymes and increased the level of detoxification phase II along with antioxidative enzymes. The histopathological studies revealed the hepatoprotective nature of the fraction in restoring the normal architecture of thioacetamide-intoxicated damaged liver. The fraction showed downregulation in the expression level of p-PI3K, p-Akt, and p-mTOR pointing towards its chemopreventive potential. The HPLC analysis of the fraction had shown the dominance of three phenolic compounds namely, catechin, epicatechin, and chlorogenic acid. The above studies comprising histopathological, immunohistochemical, and hepatic enzymes are strong indicative of the potential protective ability of ethyl acetate fraction phytoconstituents against thioacetamide-induced toxicity. Graphical abstract

In this study, a sampling campaign was conducted for 29 buildings on the National Taiwan University (NTU) campus where lead pipes were present in 4 buildings. Total lead, soluble lead, and water quality parameters including pH, temperature, residual free chlorine, and total organic carbon were measured. Results from the first-round sequential sampling (10 × 100 mL) showed that the presence of lead pipe did not necessarily cause elevated lead levels. However, the highest lead concentration and the highest frequency of exceeding 10 μg/L were detected in a building with lead pipe. Faucet was identified to be a major lead source in at least 8 buildings. No significant correlations between lead levels and water parameters were found. The building showing the highest lead level in the first round was sampled for a second round using four different methods, namely, first draw sampling, random daytime sampling, sequential sampling (5 × 1 L), and flushing sampling. Lead levels in samples collected using the four sampling methods all exceeded 10 μg/L. The first draw sampling showed the highest lead level, followed by comparable levels for random daytime sampling and sequential sampling. Flush sampling yielded the lowest lead concentration. Particles collected from the faucet aerators in 14 buildings were also characterized for their compositions and lead contents.

Seedlings of ‘Shatian pummelo’ (Citrus grandis) and ‘Xuegan’ (Citrus sinensis) were supplied daily with nutrient solution at a concentration of 0.5 (control), 100, 200, 300, 400, or 500 μM CuCl₂ for 6 months. Thereafter, seedling growth; leaf, root, and stem levels of nutrients; leaf gas exchange; levels of pigments; chlorophyll a fluorescence (OJIP) transients and related parameters; leaf and root relative water content; levels of nonstructural carbohydrates; H₂O₂ production rate; and electrolyte leakage were comprehensively examined (a) to test the hypothesis that Cu directly damages root growth and function, thus impairing water and nutrient uptake and hence inhibiting shoot growth; (b) to establish whether the Cu-induced preferential accumulation of Cu in the roots is involved in Cu tolerance of Citrus; and (c) to elucidate the possible causes for the Cu-induced decrease in photosynthesis. Most of the growth and physiological parameters were greatly altered only at 300–500 μM (excess) Cu-treated seedlings. Cu supply increased the level of Cu in the roots, stems, and leaves, with a greater increase in the roots than that in the stems and leaves. Many of the fibrous roots became rotten and died under excess Cu. These findings support the hypothesis that Cu directly damages root growth and function, thus impairing water and nutrient uptake and hence inhibiting shoot growth, and the conclusion that the preferential accumulation of Cu in the roots under excess Cu is involved in the tolerance of Citrus to Cu toxicity. The lower CO₂ assimilation in excess Cu-treated leaves was caused mainly by nonstomatal factors, including structural damage to thylakoids, feedback inhibition due to increased accumulation of nonstructural carbohydrates, decreased uptake of water and nutrients, increased production of reactive oxygen species, and impaired photosynthetic electron transport chain. Also, we discussed the possible causes for the excess Cu-induced decrease in leaf pigments and accumulation of nonstructural carbohydrates in the roots and leaves.

The potencial of Coffea arabica leaves as bioindicators of atmospheric carbon dioxide (CO₂) was evaluated in a free-air carbon dioxide enrichment (FACE) experiment by using near-infrared reflectance (NIR) spectroscopy for direct analysis and partial least squares discriminant analysis (PLS-DA). A supervised classification model was built and validated from the spectra of coffee leaves grown under elevated and current CO₂ levels. PLS-DA allowed correct test set classification of 92% of the elevated-CO₂ level leaves and 100% of the current-CO₂ level leaves. The spectral bands accounting for the discrimination of the elevated-CO₂ leaves were at 1657 and 1698 nm, as indicated by the variable importance in the projection (VIP) score together with the regression coefficients. Seven months after suspension of enriched CO₂, returning to current-CO₂ levels, new spectral measurements were made and subjected to PLS-DA analysis. The predictive model correctly classified all leaves as grown under current-CO₂ levels. The fingerprints suggest that after suspension of elevated-CO₂, the spectral changes observed previously disappeared. The recovery could be triggered by two reasons: the relief of the stress stimulus or the perception of a return of favorable conditions. In addition, the results demonstrate that NIR spectroscopy can provide a rapid, nondestructive, and environmentally friendly method for biomonitoring leaves suffering environmental modification. Finally, C. arabica leaves associated with NIR and mathematical models have the potential to become a good biomonitoring system.

In this study, the efficiency of electrochemical oxidation to treat a sanitary landfill leachate was evaluated by the reduction in physico-chemical parameters and in ecotoxicity. The acute toxicity of the sanitary landfill leachates, before and after treatment, was assessed with the model organism Daphnia magna. Electrochemical oxidation treatment was effective in the removal of organic load and ammonium nitrogen and in the reduction of metal ions concentrations. Furthermore, a reduction of 2.5-fold in the acute toxicity towards D. magna after 36 h of treatment was noticed. Nevertheless, the toxicity of the treated leachate is still very high, and further treatments are necessary in order to obtain a non-toxic effluent to this aquatic organism. Toxicity results were also compared with others described in the literature for different leachate treatments and test organisms.

The levels of toxic metals (Al, Cd, Pb) and trace metals (B, Ba, Cu, Fe, Mn, Sr, Zn) were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) in the muscle (sirloin and chuck) and liver from a total of 180 samples of steers (less than 2 years old) (Bos taurus) of foreign and local origin slaughtered on the island of La Palma (Canary Islands, Spain). As regards toxic metals, Al was the metal with the highest contents in both tissues of the foreign steers (3.75 mg/kg in the muscle and 55.3 mg/kg in the liver) and the local steers (5.60 mg/kg in the muscle and 8.65 mg/kg in the liver). In conclusion, the present study confirmed that beef is a source of trace elements, mainly Fe and Zn. In addition, the consumption of this type of beef did not show significant intakes of toxic metals (Al, Cd, and Pb) and, therefore, the consumption of the steer muscle and liver does not pose a toxicological risk for Spanish consumers.

Organochlorine pesticides (OCPs) pose a considerable threat to human and environmental health. Despite most OCPs have been banned, they are still reported to be used in developing countries, including Pakistan. We aimed to identify the distribution, origin, mobility, and potential risks from OCPs in three major environmental compartments, i.e., air, water, and soil, across Azad Jammu and Kashmir valley, Pakistan. The sums of OCPs ranged between 66 and 530 pg/g in soil, 5 and 13 pg/L in surface water, and 14 and 191 pg/m3 in air, respectively. The highest sum of OCPs was observed in the downstream zone of a river that was predominantly influenced by peri-urban and urban areas. The OCP isomers ratios (α-HCH/γ-HCH and o,p′-DDT/p,p′-DDT) indicate use of lindane and technical DDTs mixture as a source of HCH and DDT in the riverine environment. Similarly, the ratios of DDE and DDD/the sum of DDTs, α-endosulfan/β-endosulfan, and cis-chlordane/trans-chlordane indicate recent use of DDTs, endosulfan, and chlordane in the region. The air-water exchange fugacity ratios indicate net volatilization (fw/fa > 1) of α-endosulfan and trans-chlordane, and net deposition (fw/fa < 1) of β-endosulfan, α-HCH, γ-HCH p,p′-DDD, p,p′-DDE, and p,p′-DDT. Based on the risk quotient (RQ) method, we consider the acute ecological risks for fish associated with the levels of OCPs as negligible. However, more studies are recommended to evaluate the chronic ecological risks to other riverine-associated aquatic and terrestrial species as well as human health risks to the POPs exposure through food chain transfer in forthcoming years.

On December 19, 2017, China’s National Development and Reform Commission (NDRC) announced the official launch of the much-anticipated national emissions trading system (ETS), which is a critical period for the transition from the eight carbon emission trading pilot projects to the national market at this stage. Comprehensively evaluating the efficiency of China’s eight carbon trading pilots is vital for strengthening the construction of its national ETS. This paper investigates the weak-form efficiency of eight carbon trading markets in China. We use a series of variance ratio tests to identify the efficiency from the market set up to the May 4, 2018, of all markets. The results indicate that the majority of the carbon trading markets are inefficient and only Beijing, Hubei, and Fujian markets are efficient. The China’s carbon trading market is gradually maturing and implemented. In addition, we analyze the factors have impact on the market efficiency. It shows that the liquidity, volume, allocation allowance, and transparency in information are significant factors; meanwhile, the regional policy and cross cooperation also are important factors. Finally, this paper puts forward several policy recommendations on how to strengthen the effectiveness of China carbon trading markets based on the empirical results.