Colloids in groundwater or geological barriers generally play a key role in the migration of special nuclides. Adsorption characteristics of strontium were investigated on porous media in the presence of colloidal Fe(OH)₃ from the Beishan Site, the only high-level radioactive waste disposal site candidate in China. The effects of colloid amounts, solid contents, and pH were determined and studied by batch texts. The results revealed that the presence of colloidal Fe(OH)₃ in porous media contributed to promotion of the sorption effect, and the influencing factors had a significant impact on the adsorption process. The sorption ability increased with increasing colloid amount when the equilibrium time was approximately 10 h under an optimal solid-liquid ratio of 20 g L⁻¹. The sorption effect in alkaline conditions was better than that under acidic conditions. The sorption kinetics indicated that the strong chemical interaction and/or surface complexation contributed primarily to strontium sorption. The sorption isotherms and model fitting revealed that the sorption of strontium onto porous media in the presence of colloidal Fe(OH)₃ was a monolayer adsorption, and the presence of colloidal Fe(OH)₃ is an important factor that greatly influences the removal of strontium from aqueous solutions. These findings provide useful information for the treatment of strontium in radioactive waste disposal sites.

Heavy metal contamination in the Bohai Sea (China) has been the focus of many studies, but most of them only focused on local pollution levels and thus lacked high spatial resolution for the whole sea. In this study, heavy metals (i.e., As, Cr, Cu, Cd, Pb, Zn, and Fe) in surface sediments were analyzed to assess the spatio-temporal pollution conditions of the Bohai Sea, an important coastal environment consisting of Bohai Bay, Laizhou Bay, and Liaodong Bay. The results indicated that the heavy metal concentration in the sediments was in the range of 6.43–32.18 mg/kg for As, 14.90–58.07 mg/kg for Cr, 3.90–27.19 mg/kg for Cu, 0.04–0.27 mg/kg for Cd, 11.09–30.95 mg/kg for Pb, 18.76–65.58 mg/kg for Zn, and 0.78%–2.55% for Fe. The distribution of heavy metals revealed that the concentrations were relatively low in Laizhou Bay, very high in the northwest coastal region of the Bohai Sea, and decreased from near-shore to off-shore areas. Moreover, both the enrichment factor and geo-accumulation index demonstrated that there was no contamination to be found for Cr, Cu, Zn in the region and a slight to moderate pollution of As, Cd, and Pb. Cd and As presented considerable potential ecological risk as a result of their high toxicity. The potential ecological risk index (RI) suggested that a third of the areas (northwest coastal area of the Bohai Sea) has moderate ecological risk. The risk area was generally decreased as offshore distance increased, which suggested that the contamination and risk of heavy metals are influenced by anthropogenic activities.

The extensive use of neonicotinoids (NEOs) has caused the release of wide-ranging of residues to the environment and food, and their potential health risks are now receiving more attention. In this study, three surveys were conducted to obtain the overall profiles of NEO residue levels (seven NEOs and one metabolite) in Chinese tea over a period of seven years. A total of 726 tea samples were tested, and nearly 87% of the samples were found to have detectable NEO residues. The overall average detection frequency of acetamiprid was the highest, reaching 73%. Imidacloprid residues in 4.6% of the samples exceeded the Chinese maximum residue limits, whereas clothianidin and nitenpyram had been detected in Chinese tea samples since 2014. The applications of thiacloprid and thiamethoxam gradually increased, and some tea samples with high residue levels appeared in China. These findings signal the replacement of new and old varieties of NEOs in China. Both long- and short-term cumulative exposures to NEOs were calculated based on optimistic and pessimistic models recommended in the EFSA guidelines. In the three survey periods, the average total imidacloprid-equivalent concentrations were 484.63, 1713.36, and 1148.34 μg/kg, respectively. Combined with the refined point estimates and probabilistic models used in this study, the hazard quotients of NEO residues in tea for Chinese tea consumers were found to be low and within the bounds of safety.

This work aimed to investigate the metal accumulation characteristics as well as biogeochemical changes in the rhizosphere and root foraging strategies of this plant species. Previous reports suggested that Noccaea rotundifolia ssp. cepaeifolia is a Zn, Cd and Pb hyperaccumulator. We used hydroponic, rhizobox and split-pot experiments for studying metal accumulation and related rhizosphere processes. Although this species accumulated up to 1250 mg Pb kg⁻¹ and 27,000 mg Zn kg⁻¹ in shoots, translocation factors <1 do not meet the hyperaccumulation criteria. Substantial increases in Ca(NO₃)₂-extractable metals in the N. rotundifolia rhizosphere of a metal-spiked soil can be explained by proton release from N. rotundifolia roots to maintain the charge balance during excessive metal uptake; this was not observed for the non-spiked, moderately contaminated control soil. Specific rhizosphere mechanisms targeting the alleviation of metal toxicity in N. rotundifolia rhizosphere were not detected. Generally, N. rotundifolia had larger total root and shoot mass in soils with heterogeneous distribution of Zn and Pb relative to homogeneous treatments, associated with less root mass placed in metal-enriched patches. However, the avoidance strategy was not reflected by low shoot metal concentrations. Metal accumulation rates and translocation factors do not meet the criteria for hyperaccumulation. Changes of pH and DOC in N. rotundifolia rhizosphere were apparently not involved in targeted immobilisation or detoxification of Pb, Zn and Cd. Avoidance of metal-rich patches in soil is a major tolerance strategy of N. rotundifolia.

The removal of antibiotics has attracted much attention due to their extremely high adverse impacts on the environment. However, the potential risks of degradation intermediates are seldom reported. In this work, the influence of different factors on the electro-catalytic degradation efficiency of tetracycline hydrochloride (TCH) by the prepared carbon nanotubes/agarose/indium tin oxide (CNTs/AG/ITO) electrode was investigated. Under optimal conditions (10 wt% CNTs dosage, pH = 7), the maximum degradation efficiency for TCH (10 mg L⁻¹) reached up to 96% within 30 min treatment with 4 V potential. Superoxide anions (•O₂⁻) played an important role in the electro-catalytic degradation. Totally 10 degradation intermediates were identified using HPLC-MS/MS, and the degradation pathway was proposed. Toxicities of the parent antibiotic and the identified intermediates were calculated using the ECOSAR (Ecological Structure Activity Relationship) program in EPISuite, and results showed that more toxic intermediates were generated. The maximal chronic toxicity for green algae of the intermediate increased 1439.92 times. Furthermore, antimicrobial activity was further verified by disk agar biocidal tests with Escherichia coli ATCC25922 and higher biotoxicity intermediates compared with parent compounds were confirmed to be formed. Therefore, more attention should be paid on the potential risk of degradation intermediates in the treatment of wastewater containing antibiotics.

The placenta is essential for sustaining the growth of the fetus. The aim of this study was to investigate the role of the placenta in MCLR-induced significant reduction in fetal weight, especially the changes in placental structure and function. Pregnant mice were intraperitoneally injected with MCLR (5 or 20 μg/kg) from gestational day (GD) 13 to GD17. The results showed MCLR reduced fetal weight and placenta weight. The histological specimens of the placentas were taken for light and electron microscopy studies. The internal space of blood vessels decreased obviously in the placental labyrinth layer of mice treated with MCLR. After the ultrastructural examination, the edema and intracytoplasmic vacuolization, dilation of the endoplasmic reticulum and corrugation of the nucleus were observed. In addition, maternal MCLR exposure caused a reduction of 11β-hydroxysteroid dehydrogenase type 2 (HSD11B2) expression in placentae, a critical regulator of fetal development. Several genes of placental growth factors, such as Vegfα and Pgf and several genes of nutrient transport pumps, such as Glut1 and Pcft were depressed in placentas of MCLR-treated mice, however nutrient transporters Fatp1 and Snat4 were promoted. Moreover, significant increases in malondialdehyde (MDA) revealed the occurrence of oxidative stress caused by MCLR, which was also verified by remarkable decrease in the glutathione levels, total antioxidant capacity (T-AOC) as well as the activity of antioxidant enzymes. Real-time PCR and western blot analysis revealed that GRP78, CHOP, XBP-1, peIF2α and pIRE1 were remarkable increased in placentas of MCLR-treated mice, indicating that endoplasmic reticulum (ER) stress pathway was activated by MCLR. Furthermore, oxidative stress and ER stress consequently triggered apoptosis which contributed to the impairment of placental development. Collectively, these results suggest maternal MCLR exposure results in reduced fetal body weight, which might be associated with ROS-mediated endoplasmic reticulum stress and impairment in placental structure and function.

Developmental exposures to estrogenic chemicals possibly cause structural and functional abnormalities of reproductive organs in vertebrates. Bisphenol AF (BPAF), a bisphenol A (BPA) analogue, has been shown to have higher estrogenic activity than BPA, but little is known about the effects of BPAF on gonadal development, particularly gonadal differentiation. We aimed to determine whether low concentrations of BPAF could disrupt gonadal differentiation and subsequent development using Xenopus laevis, a model species for studying feminizing effects of estrogenic chemicals. X. laevis tadpoles were exposed to BPAF (1, 10, 100 nM) or 17β-estradiol (E2, positive control) from stages 45/46 to 53 and 66 in a semi-static exposure system, with a prolonged treatment with the highest concentration to the eighth week post-metamorphosis (WPM8). Gonadal morphology and histology as well as sexually dimorphic gene expression were examined to evaluate the effects of BPAF. All concentrations of BPAF caused changes in testicular morphology at different developmental stages compared with controls. Specifically, at stage 53, BPAF like E2 resulted in decreases in both the size and the number of gonadal metameres (gonomeres) in testes, looking like ovaries. Some of BPAF-treated testes remained segmented and even became discontinuous and fragmented at subsequent stages. Histological abnormalities were also observed in BPAF-treated testes, such as ovarian cavity at stages 53 and 66 and poorly developed seminiferous tubules on WPM8. At the molecular level, BPAF inhibited expression of male highly expressed genes in testes at stage 53. Correspondingly, BPAF, like E2, inhibited cell proliferation in testes at stage 50. All results show that low concentrations of BPAF inhibited testicular differentiation and subsequent development in X. laevis, along with feminizing effects to some degree. Our finding implies a risk of BPAF to the male reproductive system of vertebrates including humans.

Communities in low-income and middle-income countries (LMIC) are disproportionally affected by industrial pollution compared to more developed nations. This study evaluates the dispersal and associated health risk of contaminant-laden soil and dust at a copper (Cu) smelter in Tsumeb, Namibia. It is Africa’s only smelter capable of treating complex Cu ores that contain high arsenic (As) contents (<1%). The analyses focused on the primary trace elements associated with ore processing at the smelter: As, Cu, and lead (Pb). Portable X-Ray fluorescence spectrometry (pXRF) of trace elements in soils (n = 83) and surface dust wipes (n = 80) showed that elemental contamination was spatially associated with proximity to smelter operations. Soil concentrations were below US EPA soil guidelines. Dust wipe values were elevated relative to sites distal from the facility and similar to those at other international smelter locations (As = 1012 μg/m² (95% CI 687–1337); Cu = 1838 μg/m² (95% CI 1191–2485); Pb = 1624 μg/m² (95% CI 862–2385)). Source apportionment for Pb contamination was assessed using Pb isotopic compositions (PbIC) of dust wipes (n = 22). These data revealed that the PbIC of 73% (n = 16/22) of these wipes corresponded to the PbIC of smelter slag and tailings, indicating contribution from industrial emissions to ongoing exposure risk. Modeling of carcinogenic risk showed that dust ingestion was the most important pathway, followed by inhalation, for both adults and children. Dermal contact to trace elements in dust was also determined to pose a carcinogenic risk for children, but not adults. Consequently, contemporary smelter operations remain an ongoing health risk to the surrounding community, in spite of recent efforts to improve emissions from the operations.

Since ambient particulate matter (APM) is closely related to cardiovascular damage with mitochondria being its potential targets, this study was designed to explore the impact of APM on mitochondrial homeostasis, especially on mitochondrial dynamics and biogenesis in human vascular endothelial cells, using a kind of standard material, PM SRM1648a. As a result, internalized particles lead to mitochondrial dysfunction in EA.hy926 human endothelial cells, including mitochondrial reactive oxygen species (mtROS) overproduction, mitochondrial membrane potential (MMP) reduction and adenosine triphosphate (ATP) inhibition, coupled with additional release of mitochondrial DNA (mtDNA) into the cytosol. Moreover, morphological and structural changes in mitochondria are observed in response to PM SRM1648a. In that aspect, according to the evidence of shorter fragmented mitochondria dispersed throughout the cytoplasm, along with aberrant upregulation of fission-related mRNAs/proteins, the mitochondria exhibit a fission phenotype shifting from intact reticular network to fragmentized punctate shapes. Mechanistically, PM SRM1648a facilitates phosphorylation of DRP1 at Ser616 in HUVECs, and triggers its dephosphorylation at Ser637 residue in both EA.hy926 and HUVECs, which are supportive events for mitochondrial fission during particle exposure. Additionally, suppression of a master energy modulator, PGC-1α, reveals that PM SRM1648a has the ability to impair mitochondrial biogenesis. Collectively, it could be well concluded that PM SRM1648a interferes with the equilibrium of mitochondrial dynamics and biogenesis, which is likely to play a pivotal role in mitochondrial dysfunction driven by particles, eventually contributing to endothelial cell damage. Of note, it is more reasonable to conduct risk assessment from both cellular level and subcellular structures, among which mitochondria-targeted toxicity supplements more comprehensive understanding of APM inducible vascular toxicity.

Evaluation of the effectiveness of best management practices for reducing nitrate leaching in agricultural systems requires detailed water and nitrogen (N) budgets. A 3-year field experiment using 15 auto-weighing lysimeters was set up to quantify nitrate leaching, crop evapotranspiration (ET), and N and water use efficiencies within an intensive wheat-maize rotation system in the Northern China Plain. The lysimeter consists mainly of the following: (1) high-resolution weighing cells; (2) ceramic solution samplers for soil solutions collection; and (3) circular stainless steel leaching trays for collecting seepage water. Two N fertilizer types were applied at two rates (150 and 225 kg N hm⁻² for each crop) with no-N applied as the control. The N fertilizer types were monotypic un-coated urea and a blend product with controlled-release urea (CRU) and un-coated urea. The results indicate that when compared with un-coated urea at the same application rate, the blend product greatly improved water and N use efficiencies with significant increase in yields and crop ET as well as reduction of nitrate accumulation and leaching in the soil profile (p < 0.05). This was mostly because the blend product consistently supplied N to meet crop demands over the entire growth season. The study implied that effective best management practices to control nitrate leaching should be based on technically sound fertilization and irrigation schemes in terms of timing, rate, and fertilizer type to suit site specific conditions.