This study aimed at evaluating the interactive effects of acetaminophen (AC; 400 mg kg−1) and silicon dioxide nanomaterial (nano-SiO2;3 mg kg−1) on soil-grown barley. After 14 days of growth, plant growth, evaluated in terms of fresh and dry weight, was greatly inhibited by AC, independently of being or not co-treated with nano-SiO2. Plants growing under high levels of AC did not show any increase in malondialdehyde (MDA) nor thiols contents, though levels of superoxide anion (O2.-) and hydrogen peroxide (H2O2) were increased in leaves and roots, respectively. When plants were co-treated with nano-SiO2, reactive oxygen species (ROS) content remained unchanged, but lipid peroxidation (LP) was diminished and the thiol redox network was up-regulated in roots. The evaluation of the response of the antioxidant system showed that AC affected both non-enzymatic and enzymatic components in an organ-specific manner: proline levels and superoxide dismutase (SOD) activity were enhanced, whilst catalase (CAT) activity decreased in leaves; ascorbate content and CAT activity were diminished in roots. In response to the nano-SiO2 co-treatment, this pattern was not vastly altered, despite for ascorbate peroxidase (APX), whose activity was greatly enhanced in both organs. Overall, combining biometric, biochemical and molecular approaches, this study revealed that, although AC impaired plant growth and development, it did not trigger a harsh oxidative stress condition. Maybe by this reason, the ameliorating potential of nano-SiO2 was not so evident; yet, nano-SiO2 was able to reduce LP and to stimulate thiol content and APX activity, possibly as a defense mechanism against AC-induced stress.

With the growing production and applications of silica nanoparticles (SiNPs), human exposure to these nanoparticles continues to increase. However, the possible hazards that SiNP exposure may pose to human cardiovascular system and the underlying mechanisms remain unclear. In the present study, the flow cytometry was employed to investigate the potential of four sizes (10, 25, 50, 100 nm) of SiNPs to induce the apoptosis of human umbilical vein endothelial cells (HUVECs) in culture. The apoptotic pathway was also explored through the determination of the protein expression and/or activation of p53, Bcl-2, Bax, caspases-9, -7, -3, and PARP by western blot. The results showed that all the four sizes of SiNPs could significantly elicit apoptosis in HUVECs at the tested concentrations (1, 5, 25 μg/mL), compared with the negative control (p < 0.05, p < 0.01). Moreover, the apoptotic rates were increased with the elevating levels and decreasing sizes of administrative SiNPs, showing both dose- and size-dependent effect relationships. Interestingly, the enhancing phosphorylation of p53 protein (Ser15), decreasing ratio of Bcl-2/Bax protein, and elevating activation of the downstream proteins, caspase-9, -7, -3 and PARP, were also observed with the decreasing sizes of tested SiNPs, indicating that the p53-caspase pathway is the main way of the SiNP-mediated apoptosis in HUVECs and that the size is an important parameter that determines the SiNPs' potential to induce cellular response.

Stabilizing cadmium by incorporating it into crystalline products is an effective approach to detoxify cadmium-containing wastes. In this study, two Si-rich matrices in amorphous and crystalline forms (i.e., silica fume and α-quartz, respectively) were employed to incorporate Cd. The processing parameters, namely the type of Si-rich matrix, Cd/Si molar ratio (Г) and sintering temperature, were thoroughly investigated using quantitative X-ray diffraction technique. Cd incorporation was more energetically favored when silica fume was used rather than when α-quartz was used because of the lower Gibbs free energy of formation for silica fume. The sintering temperature and Г values substantially affected the formation of three cadmium silicates, namely monoclinic CdSiO₃, orthorhombic Cd₂SiO₄, and tetragonal Cd₃SiO₅. CdSiO₃ formed only in Г = 1.0 systems. Cd₂SiO₄ was dominant in all reactive systems. In Г = 3.0 systems, Cd₃SiO₅ rather than Cd₂SiO₄ was the predominant Cd-hosting product at temperatures above 850 °C. Leaching test results demonstrated that CdSiO₃ possessed the highest acid resistance among the cadmium silicates. The leachability of Cd₂SiO₄ was very similar to that of Cd₃SiO₅. CdSiO₃ preferred incongruent dissolution, whereas Cd₂SiO₄ and Cd₃SiO₅ favored near-congruent dissolution. This study delineated the feasibility of cadmium incorporation by Si-rich matrices, identifying a promising approach for cadmium detoxification.

An isotope-dilution ultra-performance liquid chromatography–electrospray tandem mass spectrometry method combined with dansylation was established to sensitively quantify four steroid estrogens (estrone, 17α-estradiol, 17β-estradiol and 17α-ethynylestradiol) and bisphenol A in sewage influent and effluent. A simple hexane extraction was performed from a small volume (10 mL), followed by dansyl chloride derivatization and purification with a silica cartridge. The method effectively reduced the matrix effects in sample extract and permitted the selective and sensitive determination of target compounds from complicated matrices. The detection limits of the method for steroid estrogens were 0.20–0.90 ng L⁻¹ in influent and 0.10–0.20 ng L⁻¹ in effluent samples. For bisphenol A, the limits detection of the method were 20 and 0.80 for influent and effluent samples, respectively. Recoveries of 85%–96% were observed in all matrices. The method was applied to analyze residual estrogens and bisphenol A in sewage influent and effluent samples from Beijing, China. The concentrations of bisphenol A (636–1200 ng L⁻¹) were up to 250 times higher than those of steroid estrogens. Estrone was the dominant estrogen in influent and effluent samples, while similar concentrations of 17α-estradiol and 17β-estradiol were detected in all samples.

Chemical compositions of streambed biofilms from a major river of central Japan (the Kushida River) were obtained, with data of associated sediments (fine-grained fractions < 63 μm) and dissolved components of waters, in order to provide preliminary information about biogeochemical significance of streambed biofilms. During the sampling period (July 31st to August 3rd, 2013), dissolved components of the river waters were influenced by the dam reservoir. Concentrations of NO₃⁻, silica (as Si), SO₄²⁻, PO₄³⁻ and Ca²⁺ decreased across the dam, whereas Fe and Mn increased across the dam, and then decreased downstream rapidly. Streambed biofilms contain significant amount of non-nutrient elements such as Al (up to 21% as Al₂O₃ on water and others-free basis), indicating that they are contaminated as siliciclatic (silt and clay) materials. Siliciclastic materials in the biofilms are basically compositionally similar to fine-grained (<63 μm) fractions of streambed sediments. However, some elements such as Ca, P, Mn, and Zn are markedly enriched in the biofilms. Particularly, Mn concentrations in the biofilm samples collected just below the dam reservoir are very high (∼4.0 wt %), probably due to accumulation from the discharged water. Concentrations of trace elements such as P, Cr, Cu, Zn and V appear to be controlled by amounts of Fe-oxides and/or Mn-oxides in biofilms. Numbers of factors are involved in controlling chemical compositions of streambed biofilms, including amount of contaminated siliciclastics, authigenic mineral formation, adsorption of dissolved materials and microbial metabolisms. As demonstrated by this study, systematic analyses including major elements and comparison with associated sediments and waters could reveal biogeochemistry of this complex system.

As silica nanoparticles (SiNPs) pervade the global economy, however, the followed emissions during the manufacturing, use, and disposal stages inevitably bring an environmental release, potentially result in harmful impacts. Endothelial dysfunction precedes cardiovascular disease, and is often accompanied by mitochondrial impairment and dysfunction. We had reported endothelial dysfunction induced by SiNPs, however, the related mechanisms by which SiNPs interact with mitochondria are not well understood. In the present study, we examined SiNPs-induced mitochondrial dysfunction, and further demonstrated their adverse effects on mitochondrial dynamics and biogenesis in endothelial cells (HUVECs). Consequently, SiNPs entered mitochondria, caused mitochondrial swelling, cristae disruption and even disappearance. Further analyses revealed SiNPs increased the intracellular level of mitochondrial reactive oxygen species, eventually resulting in the collapse of mitochondrial membrane potential, impairments in ATP synthesis, cellular respiration and the activities of three ATP-dependent enzymes (including Na+/K+-ATPase, Ca2+-ATPase and Ca2+/Mg2+-ATPase), as well as an elevated intracellular calcium level. Furthermore, mitochondria in SiNPs-treated HUVECs displayed a fission phenotype. Accordingly, dysregulation of the key gene expressions (FIS1, DRP1, OPA1, Mfn1 and Mfn2) involved in fission/fusion event further certified the SiNPs-induced perturbation of mitochondrial dynamics. Meanwhile, SiNPs-treated HUVECs displayed declined levels of mitochondrial DNA copy number, PGC-1α, NRF1 and also TFAM, indicating an inhibition of mitochondrial biogenesis triggered by SiNPs via PGC-1α-NRF1-TFAM signaling. Overall, SiNPs triggered endothelial toxicity through mitochondria as target, including the induction of mitochondrial dysfunction, as well as the perturbations of their dynamics and biogenesis.

Little is known about the dynamics of particulate inorganic and organic matter in brackish water controlled by tidal prism and seasonal river discharges in Macuse estuary, on central Mozambique coast, southern Africa. This manuscript illustrates seasonal variation of biogeochemical flow dynamics in a tropical estuarine system in Zambézia province. The data were collected at 42 stations, including tidal current measurements with an Acoustic Doppler Current Profiler, tidal elevation with a tidal-gauge and nitrate, silicate (SiO2), dissolved oxygen and chlorophyll-a with a photometer device system and tidal currents with multisensory instrument device (Current, Temperature and Depth device). These field data helped to calibrate a twelve months simulation of a 3D Computational Aquatic Ecosystem Dynamics Model (3D CAEDM) in 2014. The results emphasize a tidal elevation of 4-m height that generated tidal currents of 120 cm/s. They combination with seasonal runoff of ~500 m3/s from Namacurra River and averaged bathymetry morphology of 10-m depth, led on to the seasonal concentration flux of dissolved oxygen, nitrate, SiO2 and chlorophyll-a during the ebbing and flooding. In addition, the river discharges were found to be the main source of nitrate and SiO2, while the tidal prism led on the hydrological flow of the brackish-waters during the rainy season with maximum salinity anomaly of 16%. Besides the data obtained, the 3D model matches in reproducing the biogeochemical data flow have considerable potential possess of a valuable information in long- and short-term and large- and small-scale that may allow policy-makers to determine political decisions for bio-conservation, sustainability and coastal management.

Use of nanotechnology-based products is growing at large scale globally; consequently, releasing nanoparticles are entering into aquatic ecosystems. The higher surface area versus volume ratio in comparison with bulk materials makes the nanoparticles biologically more reactive. Therefore, investigating the potential aquatic toxicity of nanoparticles has become an important issue. Algae are an ideal group to study responses of different engineered nanoparticles. Present review aims to analyse the nanoecotoxicological impact of engineered metal oxide nanoparticles on algal physiology. Impacts of nanoparticles of titanium dioxide, zinc oxide, copper oxide, silica oxides, cerium oxides, iron oxide, aluminium oxide and nickel oxide are covered in details. Different factors like size, shape, pH, dose, exposure time, photo-catalytic activity, etc. that affect the toxicity of nanoparticles to test organisms are discussed in this review. Further, a host of responses shown by algae like an increase in reactive oxygen species, lipid peroxidation and a decrease in chlorophyll content and photosynthetic efficiency are highlighted. Future scope of research is also discussed in brief.

Spatiotemporal variations of dissolved nutrients were studied along Gautami-Godavari mangrove ecosystem to delineate their sources and fate. Average values of nitrate (NO3−), dissolved silica (DSi) and phosphate (PO43−) is 2.09 mg/l, 12.7 mg/l and 0.16 mg/l in wet season and 0.47 mg/l, 6.96 mg/l and 0.29 mg/l in dry season respectively. In wet season river discharge has significant influence on NO3− and DSi. In dry season, NO3− and PO43− are controlled by groundwater discharge, benthic exchange and various in situ processes owing to sediment redox condition. Mixing model shows net addition of phosphate in Coringa mangroves (95%) and Lower estuary (13%) and net removal of nitrate (24.79%) in Coringa mangrove and in estuary (58.9%). Thus present mangrove acts as net source for phosphate and net sink for nitrate and DSi. Nutrient ratio shows seasonal switching between potential Phosphorus and Nitrogen limitation in wet and dry season respectively.

Endocrine disrupting potentials were assessed for sediment samples collected near Hebei Spirit oil spill (HSOS) site, between December 2007 and January 2012. For comparison, major crude oil (CO) of HSOS, or its weathered form were assessed. Both raw extracts (REs) and their fractionated samples were tested using H295R and MVLNluc bioassays. In H295R cells, REs of crude and weathered oil (WO), and nine of 14 sediments significantly increased E2 levels, which were correlated with the concentrations of PAHs. Steroidogenic disruption potentials of the sediments generally decreased over time. Among silica fractions of all REs, aromatic hydrocarbons (F2) and polar compounds (F3) caused greater E2 levels. While, in MVLN cell bioassay, only three of 14 sediment REs showed estrogen receptor binding potencies, and no temporal trend was observed. In conclusion, oil spill can cause endocrine disruption in the affected ecosystem through steroidogenic alteration for years, and such potencies attenuate over time.