International audience | In order to determine the mechanisms of the retention of 60Co, 85Sr and 134Cs in natural silica sand columns, desorption experiments were performed by changes of pH and ionic strength and by injection of natural organic matter (NOM). Injection of KCl (0.1 M) resulted in a high release of 60Co (60-100%) and 85Sr (72-100%) but a smaller release of 134Cs (31-66%). Only limited release of 60Co (66%) and 85Sr (71%) and no release of 134Cs were observed by injection of NOM. The different percentages of desorption were related to the chemical characteristics of the organic colloids previously retained in columns before the desorption step. The results evidenced different sorption processes on energetically heterogeneous surface sites. According to the initial conditions, the binding of the radionuclides to the solid phase resulted from weak and easily reversible sorption processes to strong association probably by inner sphere complexes. The rather weak release of 134Cs by KCl was attributed to the strong retention of 134Cs by clay coatings on the natural silica sand surfaces. © 2005 Elsevier Ltd. All rights reserved.

We aimed to explore the effects of mixtures of lead and various metals on blood pressure (BP) and the odds of pre-hypertension (systolic blood pressure (SBP) 120–139 mmHg, and/or diastolic blood pressure (DBP) 80–89 mmHg) and hypertension (SBP/DBP ≥140/90 mmHg) among Chinese adults in a cross-sectional study. This study included 11,037 adults aged 18 years or older from the 2017–2018 China National Human Biomonitoring. Average BP and 13 metals (lead, antimony, arsenic, cadmium, mercury, thallium, chromium, cobalt, molybdenum, manganese, nickel, selenium, and tin) in blood and urine were measured and lifestyle and demographic data were collected. Weighted multiple linear regressions were used to estimate associations of metals with BP in both single and multiple metal models. Weighted quantile sum (WQS) regression was performed to assess the relationship between metal mixture levels and BP. In the single metal model, after adjusting for potential confounding factors, the blood lead levels in the highest quartile were associated with the greater odds of both pre-hypertension (odds ratio (OR): 1.56, 95% CI: 1.22–1.99) and hypertension (OR:1.75, 95% CI: 1.28–2.40) when compared with the lowest quartile. We also found that blood arsenic levels were associated with increased odds of pre-hypertension (OR:1.31, 95% CI:1.00–1.74), while urinary molybdenum levels were associated with lower odds of hypertension (OR:0.68, 95% CI:0.50–0.93). No significant associations were found for the other 10 metals. WQS regression analysis showed that metal mixture levels in blood were significantly associated with higher SBP (β = 1.56, P < 0.05) and DBP (β = 1.56, P < 0.05), with the largest contributor being lead (49.9% and 66.8%, respectively). The finding suggests that exposure to mixtures of metals as measured in blood were positively associated with BP, and that lead exposure may play a critical role in hypertension development.

Discarded micro/nano-plastic inputs into the environment are emerging global concerns. Yet the quantification of micro/nanoplastics in complex environmental matrices is still a major challenge, notably for soluble ones. We herein develop in-laboratory built nanostructures (zinc oxide, titanium oxide and cobalt) coupled to mass spectrometry techniques, for picogram quantification of micro/nanoplastics in water and snow matrices, without sample pre-treatment. In parallel, an ultra-trace quantification method for micro/nanoplastics based on nanostructured laser desorption/ionization time-of-flight mass spectrometry (NALDI-TOF-MS) is developed. The detection limit is ∼5 pg for ambient snow. Soluble polyethylene glycol and insoluble polyethylene fragments were observed and quantified in fresh falling snow in Montreal, Canada. Complementary physicochemical studies of the snow matrices and reference plastics using laser-based particle sizers, inductively coupled plasma tandem mass spectrometry, and high-resolution scanning/transmission electron microscopy, produced consistent results with NALDI, and further provided information on morphology and composition of the micro/nano-plastic particles. This work is promising as it demonstrates that a wide range of recyclable nanostructures, in-laboratory built or commercial, can provide ultra-trace capability for quantification for both soluble polymers and insoluble plastics in air, water and soil. It may thereby produce key missing information to determine the fate of micro/nanoplastics in the environment, and their impacts on human health.

Oxygen vacancy-enriched N/P co-doped cobalt ferrite (NPCFO) was synthesized using ionic liquid as N and P sources, and then the catalytic performance and mechanism of NPCFO upon peroxymonosulfate (PMS) activation for the degradation of organic pollutants were investigated. The as-synthesized NPCFO-700 exhibited excellent catalytic performance in activating PMS, and the degradation rate constant of 4-chlorophenol (4-CP) increased with the increase of OV concentration in NPCFO-x. EPR analysis confirmed the existence of ·OH, SO₄·⁻, and ¹O₂ in the NPCFO-700/PMS system, in which OV could induce the generation of ¹O₂ by PMS adsorption and successive capture, and also served as electronic transfer medium to accelerate the redox cycle of M²⁺/M³⁺ (M denotes Co or Fe) for the generation of radical to synergistically degrade organic pollutants. In addition, the contribution of free radical and nonradical to 4-CP degradation was observed to be strongly dependent on solution pH, and SO₄·⁻ was the major ROS in 4-CP degradation under acid and alkaline condition, while ¹O₂ was involved in the degradation of 4-CP under neutral condition due its selective oxidation capacity, as evidenced by the fact that such organic pollutants with ionization potential (IP) below 9.0 eV were more easily attacked by ¹O₂. The present study provided a novel insight into the development of transition metal-based heterogeneous catalyst containing massive OV for high-efficient PMS activation and degradation of organic pollutants.

Aging is a leading cause of mortality for the elderly and DNA methylation age is reported to be predictive of biological aging. However, few studies have investigated the associations between multiple metals exposure and accelerated aging in the elderly. We performed a pilot study of 288 elderly participants aged 50–115 years and measured genome-wide DNA methylation and 22 blood metals concentrations. Measures of DNA methylation age were estimated using CpGs from Illumina HumanMethylation EPIC BeadChip. Linear mixed regression and Bayesian kernel machine regression (BKMR) models were used to estimate the individual and overall associations between multiple metals and accelerated methylation aging. Single metal models revealed that each 1-standard deviance (SD) increase in log-transformed vanadium, cobalt, nickel, zinc, arsenic, and barium was associated with a −2.256, −1.318, 1.004, −1.926, 1.910 and −1.356 changes in ΔAge, respectively; meanwhile, for aging rate, the change was −0.019, −0.013, 0.010, −0.018, 0.023, and −0.012, respectively (all P < 0.05). The BKMR models showed reverse U-shaped associations of the overall metals mixture with ΔAge and aging rate. Downward trends of ΔAge and aging rate were observed for increasing quantiles of essential metals mixture, but upward trends were observed for non-essential metals mixture. Further individual analysis of the BKMR revealed that the 95% confidence interval of ΔAge and aging rate associated with vanadium, zinc, and arsenic did not cross 0, when other metals concentrations set at 25th, 50th, and 75th percentile. Our findings suggest reverse U-shaped associations of the overall metals mixture with accelerated methylation aging for the first time, and vanadium, zinc, and arsenic may be major contributors driving the associations.

In order to determine the current levels, spatial distribution patterns, and potential pollution of trace elements (TEs) in the atmosphere of the Tibetan Plateau (TP), snow pit samples were collected in May 2016 from five TP glaciers: Qiyi (QY), Hariqin (HRQ), Meikuang (MK), Yuzhufeng (YZF), and Xiaodongkemadi (XDKMD). Concentrations of 13 TEs (Al, Ba, Cd, Co, Cr, Cu, Fe, Li, Pb, Sb, Sr, U, and Zn) in the snow were measured. The spatial distribution patterns and depth profiles of TEs from the studies sites revealed that the influence of dust on TEs was more significant on the MK and YZF glaciers than on the QY, HRQ, and XDKMD glaciers. The spatial distributions of TE EFFₑ values differed from their concentrations, however. The enrichment factor (EF) values and concentrations of some TEs in the YZF, QY, and XDKMD glaciers revealed that the pollution levels of these elements were significantly lower than those found in previous research. Examination based on EFs, principal component analysis, as well as the calculated non-dust contributions of TEs, revealed that dust was the principal source for most TEs in all five glaciers, while biomass burning was another potential natural source for TEs in some glaciers, such as QY. In contrast, Cd, Ba, Sr, Cu, Pb, Zn, and Sb were occasionally affected by anthropogenic sources such as road traffic emissions, fossil fuel combustion, and mining and smelting of nonferrous metals in and beyond the TP. Air mass backward trajectories revealed that potential pollutants were transported not only from local sources but also from Xinjiang Province in northwestern China, as well as South Asia, Central Asia, the Middle East, and Europe.

Microplastics are known to be associated with co-contaminants, but little is understood about the mechanisms by which these chemicals are transferred from ingested plastic to organisms. This study simulates marine avian gastric conditions in vitro to examine the bioaccessibility of authigenic metals (Fe, Mn) and trace metals (Co, Pb) that have been acquired by polyethylene microplastic pellets from their environment. Specifically, different categories of pellet were collected from beaches in Cornwall, southwest England, and exposed to an acidified saline solution of pepsin (pH ∼ 2.5) at 40 °C over a period of 168 h with extracted metal and residual metal (available to dilute aqua regia) analysed by ICP-MS. For Fe, Mn and Co, kinetic profiles consisted of a relatively rapid initial period of mobilisation followed by a more gradual approach to quasi-equilibrium, with data defined by a diffusion model and median rate constants ranging from about 0.0002 (μg L⁻¹)⁻¹ h⁻¹ for Fe to about 7 (μg L⁻¹)⁻¹ h⁻¹ for Co. Mobilisation of Pb was more complex, with evidence of secondary maxima and re-adsorption of the metal to the progressively modified pellet surface. At the end of the time-courses, maximum total concentrations were 38.9, 0.81, 0.014 and 0.10 μg g⁻¹ for Fe, Mn, Co and Pb, respectively, with maximum respective percentage bioaccessibilities of around 60, 80, 50 and 80. When compared with toxicity reference values for seabirds, the significance of metals acquired by microplastics from the environment and exposed to avian digestive conditions is deemed to be low, but studies of a wider range of plastics and metal associations (e.g. as additives) are required for a more comprehensive risk assessment.

Natural sources, such as soil and wind-erosion dust (SWD), biomass open burning (BOB), sea salt spray (SSAS) and biogenic source (BIO), are major contributors to atmospheric emissions of trace elements (TEs) globally. In this study, we used a comprehensive approach to account for area-, production- and biofuel consumption-based emission factor calculation methods, and thus developed an integrated high-resolution emission inventory for 15 types of TEs (As, B, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, V and Zn) originated from natural sources in China for the year 2015. The results show that national emissions of TEs in 2015 range from 7.45 tons (Hg) to 1, 400 tons (Zn) except for the extremely high emissions of Mn (10, 677 tons). SWD and BIO are identified as the top two source contributors, accounting for approximately 67.7% and 26.1% of the total emissions, respectively. Absolute emissions of TEs from natural sources are high in the Xinjiang, Inner Mongolia and Tibet autonomous regions with large areas of bare soil and desert. However, emission intensity of TEs per unit area in the Southern provinces of China is higher than those in Northern China and Southwestern China, with the Yunnan and Sichuan provinces displaying the highest emission intensity. Our results suggest that controlling SWD can play a significant role in reducing fugitive particulate matter and the associated emissions of TEs from natural sources in China; and desertification control is particularly critical in the Northwest provinces where the majority of deserts are located.

Nickel and cobalt are essential elements that become toxic at high concentrations. Little is known about nickel and cobalt toxicity in aquatic animals. This study aimed to investigate acute and chronic toxicity of nickel and cobalt in Japanese flounder (Paralichthys olivaceous), with emphasis on oxidative stress reactions, histopathological changes, and differences in gene expression. The lethal concentration for 50% mortality (LC₅₀) in 3 and 8 cm Japanese flounder exposed to nickel for 96 h was found to be 86.2 ± 0.018 and 151.3 ± 0.039 mg/L; for cobalt exposure, LC₅₀ was 47.5 ± 0.015 and 180.4 ± 0.034 mg/L, respectively. Chronic nickel and cobalt exposure caused different degrees of oxidative enzyme activity changes in gill, liver, and muscle tissues. Erythrocyte deformations were detected after acute or chronic exposure to nickel and cobalt. the nickel and cobalt exposure also caused pathological changes such as spherical swelling over other gill patches, rod-like proliferations in the gill patch epithelial cell layer, and disorder in hepatocyte arrangement, cell swelling, and cytoplasm loosening. RNA-Seq indicated that there were 184 upregulated and 185 downregulated genes in the liver of Japanese flounder exposed to 15 mg/L nickel for 28 d. For cobalt, 920 upregulated and 457 downregulated genes were detected. Among these differentially expressed genes, 162 were shared by both nickel and cobalt exposure. In both nickel and cobalt, pathways including fatty acid elongation, steroid biosynthesis, unsaturated fatty acid biosynthesis, fatty acid metabolism, PPAR signaling, and ferroptosis were significantly enriched. Taken together, these results aided our understanding of the toxicity of nickel and cobalt in aquatic animals.

Kaolinite supported CoFe₂O₄ (KCF) was synthesized and employed to adsorb doxycycline (DOX), an antibiotic and Congo red (CR), a dye from aqueous solution. The prepared KCF nanocomposite was treated in a muffle furnace at 300, 500 and 700 °C, and thereafter characterized. X-ray diffractogram revealed structural damage of kaolinite and appearance of distinct peaks of CoFe₂O₄ with an increase in calcination temperature, while transmission electron microscopy (TEM) images showed that CoFe₂O₄ nanoparticles were supported on the lamellar surface of kaolinites. Comparative adsorption mechanism of the two targeted contaminants showed that adsorption of DOX was influenced by hydrogen bond and n-π interaction, while that of CR was due to hydrophobic interaction and hydrogen bond. However, the adsorption of the two contaminants was best fitted to the isotherm that was proposed by Langmuir, with a monolayer maximum adsorption capacity of 400 mg g⁻¹ at 333 K for DOX, and 547 mg g⁻¹ at 298 K for CR. The removal of DOX from aqueous solution was favored by an increase in temperature (endothermic), while that of CR was exothermic. Thermodynamics studies confirmed that the adsorption of the two contaminants is feasible and spontaneous. The presence of natural organic matter (NOM) did not affect the removal of the two contaminants. Regeneration and reusability study showed that KCF is economically viable. Therefore, introducing inorganic particles like cobalt ferrite into the matrix of kaolinites provides a composite with promising adsorption capacity.