In this study, a series of BUC-21/titanate nanotube (BT-X) composites were facilely fabricated via ball-milling of 2-dimensional (2D) metal-organic framework (MOF) BUC-21 and titanate nanotubes (TNTs). The BT-X composites were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), UV–visible diffuse-reflectance spectroscopy (UV–vis DRS), X-ray photoelectron spectrometer (XPS) and high resolution transmission electron microscopy (HRTEM). Both the photocatalytic reduction from Cr(VI) to Cr(III) and adsorptive removal of formed Cr(III) of BT-X composites were systematically investigated under different conditions including pH values and co-existing inorganic ions. It was found that BUC-21 (100 mg)/TNTs (100 mg) (BT-1) composites demonstrate remarkable ability of photocatalytic Cr(VI) reduction and adsorptive Cr(III) removal, as well as good reusability and stability. It is believed that the introduction of TNTs could capture the formed Cr(III) from the surface of BUC-21, which provided more active sites exposed to enhance the Cr(VI) reduction.

To mitigate severe wintertime pollution events in Western China, identifying the source of atmospheric fine particles with an aerodynamic diameter of ≤2.5 μm (PM2.5) is a crucial step. In this study, we first analyzed the meteorological and emission factors that caused a considerable increase in the PM2.5 concentration in December 2016. This severe pollution episode was found to be related with unfavorable meteorological conditions and increased residential emissions. The WRF-Chem simulations were used to calculate the residential contribution to PM2.5 through a hybrid source apportionment method. From the validation that used grid data and in situ observations in terms of meteorological elements, PM2.5 and its compounds, the simulated results indicated that the residential sector was the largest single contributor to the PM2.5 concentration (60.2%), because of its predominant contributions to black carbon (BC, 62.1%) and primary organic aerosol (POA, 86.5%), with these two primary components accounting for 70.7% of the PM2.5 mass. Compared with the remote background (RB) region covering the central part of the Tibetan Plateau, the residential sector contributed 11.3% more to PM2.5 in the highly populated mega-city (HM) region, including the Sichuan and Guanzhong Basins, due to greater contribution to the concentrations of primary PM2.5 components. As the main emission source of sulfur dioxide (SO2), nitrogen oxides (NOx), and secondary organic aerosol (SOA), the industrial sector was the second largest contributor to the PM2.5 concentration in the HM region. However, in the RB region, the dominating emissions of NOx, SOA, and BC were from the transport sector; thus, it was the next largest contributor to total PM2.5. An evaluation of the emission control experiment suggested that mitigation strategies that reduce emissions from residential sources can effectively reduce the PM2.5 concentration during heavy pollution periods.

Schwertmannite (SCH) has strong adsorption ability to As(III). However, there are few reports on the stability of SCH load with As(III) (SCH-As(III)). In this study, the effects of tartaric acid (TA), pH and coexisting ions including K+, Ca2+, Al3+ and CO32− on the photoreductive dissolution of SCH- As(III) and the release of the adsorbed As (III) were investigated. The results showed that under UV irradiation TA could greatly enhance the release of total Fe and total As from SCH-As(III). Nevertheless, the total Fe and total As in the solution decreased when TA was consumed up. Compared to SCH, the reductive dissolution of SCH-As(III) was obviously suppressed. In the dark, TA could slowly enhance the dissolution of SCH-As(III), but its effect on the release of adsorbed As(III) was weak. Low pH was conducive to the release of iron and arsenic. Ca2+, K+, and CO32− promoted the decrease of the dissolved total Fe in the later reaction. However, Al3+ inhibited the decrease of the dissolved total Fe and total As. The analyses of FTIR and XRD demonstrated that the mineralogical phase of SCH-As(III) after reaction changed. With light, the dissolved total Fe and total As existed mainly as Fe(II) and As(V), respectively. This is because Fe(II) was generated via ligand to metal charge transfer and As(III) was oxidized to As(V) by ·OH produced during the reaction. Thus, this study provides us with a comprehensive understanding of the stability of SCH-As(III) and the release of adsorbed As(III) in natural environments.

Urban wastewater effluents bring large amounts of nutrients, organic matter and organic microcontaminants into freshwater ecosystems. The effects of this complex mixture of pollutants on freshwater invertebrates have been studied mainly in temperate rivers and streams with high dilution capacities. In contrast, Mediterranean streams and rivers have lower dilution capacities especially during the seasonal drought, and are therefore exposed to high concentrations of pollutants. Here, we assess the effects of urban wastewater pollution on invertebrate communities from Mediterranean streams under different hydrological conditions. Specifically, we assessed the invertebrates taxonomic composition and functional biological traits in 12 streams, differing in stream and substrate size (sand or cobbles), under low (2 surveys) and baseflow (1 survey) conditions. In each stream, we selected reaches both upstream and downstream of the wastewater discharge point. Our results indicate that urban wastewater pollution favours the most tolerant invertebrate taxa and homogenises functional trait composition over time. Changes in functional traits were more evident during the seasonal drought, when the low flow conditions at the upstream and downstream sites were more severe and, pollutant concentrations downstream were at their highest. However, the effects of urban wastewater pollution were not uniform in the downstream sites; as local invertebrate communities differed in according to the river substrate and stream size (i.e., width and discharge). Overall, urban pollution caused by wastewater enhanced both, taxonomic and functional differences between the invertebrate communities. Such an absence of homogenisation among wastewater pollution impacted sites was probably related to the relevant role of stream substrate-size as well flow conditions in the rivers receiving the impact. These are attributes that need to be considered when setting the pollutant discharge limits in rivers and streams receiving effluents.

Over the last decades, plastic debris has been identified and quantified in the marine environment. Coastal and riverine input have been recognized as sources of plastic debris, whereas oceanic gyres and sediments are understood to be sinks. However, we have a limited understanding of the fate of plastic debris in the nearshore environment. To investigate the movement and distribution of plastic debris in the nearshore environment, we collected samples at three distinct locations: below the high tide line, the turbulent zone created by the combination of breaking wave and backflush (defined as the boundary), and the outer nearshore. We estimated the abundance and physical characteristics (e.g. density, hardness, etc.) of macroplastic and microplastics. Four times and 15 times more macroplastics and microplastics are observed, respectively, at the boundary than in the outer nearshore waters, which suggests an accumulation driven by the physical properties of the plastic particles such as density, buoyancy and surface area. We further report that highly energetic conditions characteristic of the boundary area promote the long-term suspension and/or degradation of low density, highly buoyant or large surface area plastic debris, leading to their preferential accumulation at the boundary. Contrastingly, denser and low surface area plastic pieces were transported to the outer nearshore. These results emphasize the role of selective plastic movement at the nearshore driven by physical properties, but also by the combined effects of several hydrodynamics forces like wave action, wind or tide in the resuspension, as well as degradation and transport of plastic debris out of the nearshore environment.

That an alteration of the intestinal permeability is associated with gut barrier function has been increasingly evident, which plays an important role in human and animal health. Bisphenol A (BPA), an industrial compound used worldwide, has recently been classified as an environmental pollutant. One of our earlier studies has demonstrated that BPA disrupts the intestinal barrier function by inducing apoptosis and inhibiting cell proliferation in the human colonic epithelial cells line. In this study, we investigated the effects of dietary BPA uptake on the colonic barrier function in mice, as well as the intestinal permeability. Dietary BPA uptake was observed to destroy the morphology of the colonic epithelium and increase the pathology score. The levels of endotoxin, diamine peroxidase, D-lactate, and zonulin were found to have been significantly elevated in both plasma and colonic mucosa. A decline in the number of intestinal goblet cells and in mucin 2 gene expression was observed in the mice belonging to the BPA group. The results of immunohistochemistry revealed that the expression of tight junction proteins (ZO-1, occludin, and claudin-1) in colonic epithelium of BPA mice decreased significantly, and their gene abundance was also inhibited. Moreover, dietary BPA uptake was also found to have significantly reduced colonic microbial diversity and altered microbial structural composition. The functional profiles of colonic bacterial community exhibited adverse effects of dietary BPA intake on the endocrine and digestive systems, as well as the transport and catabolism functions. Collectively, our study highlighted that dietary BPA increased the colonic permeability, and this effect was closely related to the disruption of intestinal chemistry and physical and biological barrier functions.

Only 1% of plastic entering the ocean is found floating on its surface, with high loads in ocean accumulation zones and semi-enclosed seas, except for the Red Sea, which supports one of the lowest floating plastic loads worldwide. Given the extension of reefs in the Red Sea, we hypothesize a major role of scleractinian corals as sinks, through suspension-feeding, and assessed microplastic removal rates by three Red Sea coral species. Experimental evidence showed removal rates ranging from 0.25 × 10⁻³ to 14.8 × 10⁻³ microplastic particles polyp⁻¹ hour⁻¹, among species. However, this was only 2.2 ± 0.6% of the total removal rate, with passive removal through adhesion to the coral surface being 40 times higher than active removal through suspension-feeding. These results point at adhesion of plastic to coral reef structures as a major sink for microplastics suspended in the water column after sinking, helping explain low concentrations in Red Sea surface waters.

Researches had shown that silica nanoparticles (SiNPs) could reduce the quantity and quality of sperms. However, chronic effects of SiNPs have not been well addressed. In this study, mice spermatocyte cells (GC-2spd cells) were continuously exposed to SiNPs (5 μg/mL) for 30 passages and then the changes of microRNA (miRNA) profile and mRNA profile were detected. The function of miRNAs was verified by inhibitors to explore the regulation role of miRNAs in reproductive toxicity induced by SiNPs. The results showed that SiNPs induced cytotoxicity, and activated autophagy in GC-2spd cells. SiNPs led to a total of 1604 mRNAs (697 up-regulated and 907 down-regulated) and 15 miRNAs (6 up-regulated such as miRNA-138 and miRNA-494 and 9 down-regulated) with different expression in GC-2spd cells. The combined miRNA profile and mRNA profile showed that 415 mRNAs with different expression in 5 μg/mL SiNPs group were regulated by miRNA. Furthermore, our study demonstrated that SiNPs decreased the expressions of AKT mRNAs. Moreover, SiNPs had an activation effect on the AMPK/TSC/mTOR pathway. However, inhibitor of miRNA-494 could attenuate the expression levels of AMPK, TSC, LC3Ⅱ and alleviate the decreased of AKT, mTOR, p-mTOR induced by SiNPs. The above results suggested that the low-dose SiNPs exposure could promote autophagy by miRNA-494 targeting AKT, thereby activating AMPK/TSC/mTOR pathway in GC-2spd cells. MiRNA-494 is an important regulator of autophagy by targeting AKT, which provides new evidence for the male reproductive toxicity mechanism of SiNPs.

Microplastics are defined as plastic fragments <5 mm, and they are found in the ocean where they can impact on the ecosystem. Once released in seawater, microplastics can be internalized by organisms due to their small size, moreover they can also leach out several additives used in plastic manufacturing, such as plasticizers, flame retardants, etc., resulting toxic for biota. The aim of this study was to test the toxicity of micronized PVC products with three different colors, upon Paracentrotus lividus embryos. In particular, we assessed the effects of micronized plastics and microplastic leachates. Results showed a decrease of larval length in plutei exposed to low concentrations of micronized plastics, and a block of larval development in sea urchin embryos exposed to the highest dose. Virgin PVC polymer did not result toxic on P. lividus embryos, while an evident toxic effect due to leached substances in the medium was observed. In particular, the exposure to leachates induced a development arrest immediately after fertilization or morphological alterations in plutei. Finally, PVC products with different colors showed different toxicity, probably due to a different content and/or combination of heavy metals present in coloring agents.

A novel self-assembly method was developed to prepare a γ-Fe₂O₃/graphene oxide (GO) heterogeneous catalyst that showed excellent synergy between photocatalysis and Fenton-like reactions. The γ-Fe₂O₃/GO catalyst prepared on the iron plates demonstrated efficient and reproducible catalytic activities for water treatment. It takes only 80 min to degrade 50 mg L⁻¹ methylene (MB) completely, which is the main non-biodegradable dye in wastewater from the textile industry. The heterogeneous catalyst is stable over a wide range of pH (from 2.0 to 10.2) for MB degradation, and can be easily extracted from solution and repeatedly used with little loss of catalytic activity. The high activity and stability of the catalyst system can be attributed to charge separation between γ-Fe₂O₃ and GO, which could accelerate Fenton-like process and photocatalysis. In addition, the dominant reactive oxidant species responsible for the MB degradation, including the hydroxyl radicals (•OH) and holes (h⁺), were trapped on the surface of the γ-Fe₂O₃/GO composite, as proved by a free-radical quenching experiment. The γ-Fe₂O₃/GO heterogeneous catalyst could potentially provide a solution for removal of non-biodegradable dyes from wastewater in the textile industry.