41 ref. doi:10.1016/j.envpol.2003.12.023 | International audience | Metal distribution patterns in superficial soil horizons of agricultural land affected by metallurgical point-source pollution were studied using optical and electron microscopy, synchrotron radiation and spectroscopy analyses. The site is located in northern France, at the center of a former entry lane to a bunker of World War II, temporarily paved with coarse industrial waste fragments and removed at the end of the war. Thin sections made from undisturbed soil samples from A and B horizons were studied. Optical microscopy revealed the occurrence of yellow micrometer-sized (Ap horizon) and red decamicrometer-sized spherulites (AB, B1g horizons) as well as distinct distribution patterns. The chemical composition of the spherulites was dominated by Fe, Mn, Zn, Pb, Ca, and P. Comparison of calculated Zn stocks, both in the groundmass and in spherulites, showed a quasi-exclusive Zn accumulation in these neoformed features. Their formation was related to several factors: (i) liberation of metal elements due to weathering of waste products, (ii) Ca and P supply from fertilizing practices, (iii) co-precipitation of metal elements and Ca and P in a porous soil environment, after slow exudation of a supersaturated soil solution in more confined mineral media.

To evaluate the influence of surface coatings on nano-fertilizers uptake and their phytotoxicity to crops and its health risk to Chinese adults, trisodium citrate (TC) and polyethylene glycol (PEG) coatings were prepared on the surface of copper oxide nanoparticles (CuO NPs), respectively, with 100 and 500 mg/L of bare CuO NPs, TC-CuO NPs, and PEG-CuO NPs were exposed to soil-grown Ipomoea aquatica Forssk. Combined bio-transmission electron microscopy and micro-CT observed cellular migration of coated CuO NPs in symplastic and apoplastic pathways, as well as nanoparticles transported through vascular tissues to the above-ground parts. Since TC-CuO NPs had less inhibition on vascular phylogeny of I. aquatica roots which was determined by RT-qPCR, their migration in plants was more efficient, thus exhibiting greater phytotoxicity to shoots. Meanwhile, coatings significantly reduced the phytotoxicity of CuO NPs by stimulating plant antioxidant defense. The risk of CuO nano-fertilizers on human dietary safety was evaluated, the HQ > 1 in the 500 mg/L CuO NPs treatment indicated a potential health risk to Chinese adults, which was reduced by the coatings. This work explored for the first time the mechanism of coating effects on nanoparticles migration efficiency and phytotoxicity at the molecular level and demonstrated that the migration of nanoparticles between tissues could have an impact on phytotoxicity. It implied that coating can be tailored to target nanoparticles to specific regions of the plant. In addition, this study highlights the potential health risks associated with the consumption of I. aquatica fertilized with CuO NPs and provides valuable insights into the environmental applications of nano-fertilizers.

As a result of the efforts to introduce the principle of the 3Rs (replacement, reduction, and refinement) into animal testing, alternative in vitro skin corrosion test methods have been developed and standardized globally. However, alternative in vitro skin corrosion test methods have some limitations in terms of the use of humanely killed rats or commercial models and kits. The present study focused on the applicability of invertebrates as alternative in vivo skin models. Even though earthworm skin comprises the same biomolecules as human skin, the possibility of using earthworm skin as an alternative for skin testing remains unexplored. In this study, we developed a half-pipe tool for earthworm skin corrosion testing and optimized the test protocol. Subsequently, the applicability of the earthworm half-pipe assay for corrosion testing with six chemicals, including inorganic acids, organic acids, and alkalis, was investigated using stereomicroscopy and electron microscopy. It was observed that the specific concentrations for earthworm skin corrosion were lower than those for animal or in vitro tests. Therefore, the sensitivity of the earthworm half-pipe assay indicates that it could be useful as a screening tool before conducting in vivo animal tests or in vitro skin tests. This new method can contribute to research on alternative skin corrosion tests by reducing ethical issues, time, and cost while achieving effective results.

Large amounts of aluminum (Al) are found in wastewater from industrial bauxite mining, which is often responsible for the contamination of drinking water sources in urban and rural communities. Although this metal exhibits broad environmental distribution, its cardiac repercussions are poorly understood, making it difficult to establish diagnostic criteria in cases of Al intoxication. In the absence of clinical data, we used a preclinical model to investigate the impact of Al exposure on heart bioaccumulation, molecular oxidation, micromineral distribution, structural and ultrastructural remodeling of the cardiac tissue. Male Wistar rats were equally randomized into five groups: G1 = distilled water; and G2 to G5 = 0.02, 0.1, 50, and 200 mg/kg aluminum solution, respectively. After 120 days, the hearts were collected and subjected to mineral microanalysis, immunoenzymatic detection of 8-OHdG, as well as bright field, polarizing, scanning and transmission electron microscopy to estimate the extent of the cardiac remodeling and cardiomyocytes ultrastructure. Long-term Al exposure induced dose-dependent bioaccumulation, micromineral imbalance, genomic DNA oxidation, structural and ultrastructural abnormalities of the cardiac tissue, resulting in extensive parenchymal loss, stromal expansion, diffuse inflammatory infiltrate, increased glycoconjugate and collagen deposition, subversion and collapse of the collagen network, reduced myocardial vascularization index, mitochondrial swelling, sarcomere disorganization, myofilament dissociation, and fragmentation in cardiomyocytes. Our findings indicated that the heart was sensitive to Al-mediated toxicity, especially in animals treated with the three highest doses of Al. In response to Al-induced loss of the parenchyma, heart stroma exhibited a reactive and compensatory expansion, which, in combination with the increased distribution of thick myofibrils and degenerated mitochondria in cardiomyocytes, provides morphological evidence that cardiac tissue adaptations are not enough to adjust the relationships between the parenchyma and stroma until a steady state is reached, resulting in continuous pathological remodeling potentially associated with Al-induced proinflammatory and pro-oxidant events.

Little is known about pollution in urban snow and how aerosol and gaseous air pollutants interact with the urban snowpack. Here we investigate interactions of exhaust pollution with snow at low ambient temperature using fresh snow in a temperature-controlled chamber. A gasoline-powered engine from a modern light duty vehicle generated the exhaust and was operated in homogeneous and stratified engine regimes. We determined that, within a timescale of 30 min, snow takes up from the exhaust a large mass of organic pollutants and aerosol particles, which were observed by electron microscopy, mass spectrometry and aerosol sizers. Specifically, the concentration of total organic carbon in the exposed snow increased from 0.948 ± 0.009 to 1.828 ± 0.001 mg/L (homogeneous engine regime) and from 0.275 ± 0.005 to 0.514 ± 0.008 mg/L (stratified engine regime). The concentrations of benzene, toluene and 13 out of 16 measured polycyclic aromatic hydrocarbons (PAHs), particularly naphthalene, benz[a]anthracene, chrysene and benzo[a]pyrene in snow increased upon exposure from near the detection limit to 0.529 ± 0.058, 1.840 ± 0.200, 0.176 ± 0.020, 0.020 ± 0.005, 0.025 ± 0.005 and 0.028 ± 0.005 ng/kg, respectively, for the homogeneous regime. After contact with snow, 50–400 nm particles were present with higher relative abundance compared to the smaller nanoparticles (<50 nm), for the homogeneous regime. The lowering of temperature from 25 ± 1 °C to (−8) – (−10) ± 1 °C decreased the median mode diameter of the exhaust aerosol particles from 69 nm to 57 nm (p < 0.1) and addition of snow to 51 nm (p < 0.1) for the stratified regime, but increased it from 20 nm to 27 nm (p < 0.1) for the homogeneous regime. Future studies should focus on cycling of exhaust-derived pollutants between the atmosphere and cryosphere. The role of the effects we discovered should be evaluated as part of assessment of pollutant loads and exposures in regions with a defined winter season.

Perfluorooctanesulphonic acid (PFOS) is a ubiquitous contaminant in the aquatic environment and our earlier studies demonstrated that chronic PFOS exposures lead to a female-biased sex ratio and decreased sperm quality in male zebrafish. The underlying mechanism for these reproductive effects is unknown. In the present study, 8 h post-fertilization (hpf) zebrafish were exposed to PFOS at 250 μg/L for 5 months, and the levels of sex hormones, expression of sex determination related genes, and histological and ultrastructural changes of gonads were fully characterized. During the sex differentiation period, we observed elevated estradiol (E2) and decreased testosterone (T) levels in whole tissue homogenates from PFOS exposed juveniles. In fully mature adult male fish, serum E2 levels were slightly increased, however, the estrogen receptor alpha (esr1) was significantly elevated in PFOS treated male gonads. Histological and electron microscopic examinations revealed structural changes in the gonads of PFOS exposed male and female adult zebrafish. In summary, chronic PFOS exposure disrupts sex hormone level and related gene expression and impairs gonadal development, which may contribute to the previously reported PFOS reproductive toxicity.

The degree of aggregation and/or coalescence of Au-citrate nanoparticles (AuNPs, mean size 21.5 ± 2.9 nm), after delivery in simulated seawater, are shown to be concentration-dependent. At low concentrations no coalescence and only limited aggregation of primary particles were found. Experiments were performed in which the marine bivalve (Ruditapes philippinarum) was exposed to AuNPs or dissolved Au and subsequently, bivalve tissues were studied by Scanning and Transmission Electron Microscopy and chemical analyses. We show that the bivalve accumulates gold in both cases within either the digestive gland or gill tissues, in different concentrations (including values of predicted environmental relevance). After 28 days of exposure, electron-dense deposits (corresponding to AuNPs, as proven by X-ray microanalysis) were observed in the heterolysosomes of the digestive gland cells. Although non-measurable solubility of AuNPs in seawater was found, evidence is presented of the toxicity produced by Au3+ dissolved species (chloroauric acid solutions) and its relevance is discussed.

This study investigates the incidence of MPs in surface sediment samples, collected from the Anzali Wetland, Gillan province, North of Iran. This natural habitat receives municipal wastewater effluents and hosts industries and recreational activities that could release plastic to the wetland. There is need for studies to understand MPs pollution in wetlands. A total of 40 superficial sediment samples were taken covering potential pollution hotspots in the wetland. The average level of MPs was 362 ± 327.6 MP/kg: the highest MPs levels were near the outlet of a highly urbanized river (Pirbazar River) (1380 MP/kg), which runs through Rasht city. This was followed by 1255 MP/kg where there was intense fishing, boating and tourism activities in the vicinity of Bandar-e Anzali city. Fibers were the most common type of MPs (80% of the total MPs detected). The MPs polluting the wetland were predominantly white/transparent (42%), and about 40% of them were >1000 μm. Polypropylene (PP) and polyethylene (PE) prevailed in MPs found. MPs were characterized with polarized light microscopy, Raman spectroscopy, Scanning Electron Microscopy coupled with Energy-Dispersive X-ray spectroscopy. Microplastics levels were found to correlate significantly (p > 0.7) with electrical conductivity (EC) and sand-size fraction of the sediments. Coarse-grained sediments presented large capacity to lodge the MPs. This study can be used to establish protection policies in wetlands and newly highlights the opportunity of intercepting MPs in the Anzali Wetland, which are generally >250 μm, before they fragment further.

Di-(2-ethylhexyl) phthalate (DEHP) possesses the potential to interfere with the male reproductive endocrine system in mammals; however, its reproductive toxicity in male zebrafish and associated epigenetic studies have not been explored. In this study, three-month-old male zebrafish were exposed to environmentally relevant concentrations of DEHP (0, 10, 33 and 100 μg/L) for 3 months, and then the impact on the reproduction of males and the underlying mechanism were investigated. Histological testing showed that an exposure concentration of 100 μg/L DEHP significantly inhibited spermatogenesis, with an associated decline in capability to fertilize untreated oocytes. Electron microscopic examinations also revealed noticeable damage to the testicular ultrastructure at the 100 μg/L DEHP exposure level. In addition, exposure to 33 and 100 μg/L of DEHP resulted in a decline of circulating testosterone (T) and an increase in the level of 17β-estradiol (E2), both of which were possibly derived from the downregulation of cyp17a1 and hsd17b3 genes and the upregulation of the cyp19a1a gene in the gonads. The DNA methylation statuses of these genes were altered within their promoter regions. A significant increase in global DNA methylation in both the male testes and their offspring larvae was observed at higher exposure concentration of DEHP. Our findings demonstrate that exposure to environmentally relevant concentrations of DEHP can damage the testes, disturbe the sex hormones production, and inhibite spermatogenesis, which ultimately impairs the reproduction of male zebrafish.

Ultrafine (<100 nm) particles related to traffic are of high environmental and human health concern, as they are supposed to be more toxic than larger particles. In the present study transmission electron microscopy (TEM) is applied to obtain a concrete picture on the nature, morphology and chemical composition of non-volatile ultrafine particles in the exhaust of state-of-the-art, Euro 6b, Gasoline and Diesel vehicles. The particles were collected directly on TEM grids, at the tailpipe, downstream of the after-treatment system, during the entire duration of typical driving cycles on the chassis dynamometer. Based on TEM imaging coupled with Energy Dispersive X-ray (EDX) analysis, numerous ultrafine particles could be identified, imaged and analyzed chemically. Particles <10 nm were rarely detected. The ultrafine particles can be distinguished into the following types: soot, ash-bearing soot and ash. Ash consists of Ca, P, Mg, Zn, Fe, S, and minor Sn compounds. Most elements originate from lubricating oil additives; Sn and at least part of Fe are products of engine wear; minor W ± Si-bearing nearly spherical particles in Diesel exhaust derive from catalytic coating material. Ultrafine ash particles predominate over ultrafine soot or are nearly equal in amount, in contrast to emissions of larger sizes where soot is by far the prevalent particle type. This is probably due to the low ash amount per volume fraction in the total emissions, which does not favor formation of large ash agglomerates, opposite to soot, which is abundant and thus easily forms agglomerates of sizes larger than those of the ultrafine range. No significant differences of ultrafine particle characteristics were identified among the tested Gasoline and Diesel vehicles and driving cycles. The present TEM study gives information also on the imaging and chemical composition of the solid fraction of the unregulated sub-23 nm size category particles.