Dust-phase phthalates in university dormitories in Beijing, China: pollution characteristics, potential sources, and non-dietary oral exposure.

This study aimed to determine dust-phase phthalate levels in 112 dormitories of 14 universities during autumn and winter, investigate their potential sources, and estimate phthalate exposure via dust ingestion. Twelve phthalates were detected, among which di-(2-ethylhexyl) phthalate (DEHP) and dicyclohexyl phthalate (DCHP) were the most abundant, followed by di-isobutyl phthalate (DiBP) and di-n-butyl phthalate (DnBP). The median concentrations and contributions of DCHP and DEHP were the highest. The contributions of di-n-octyl phthalate and di-nonyl phthalate were higher in winter than in autumn. Potential sources included iron furniture, chemical fiber textiles, clothes, and personal care products. Medium-density fiberboard furniture is a potential sink for phthalates. In two seasons, DEHP, DCHP, DiBP, and DnBP were the main phthalates ingested by college students . The median oral exposure of ten phthalates was higher in females than in males. College students have a high risk of exposure to DEHP in dormitories.

Dust phase and window film phase phthalates in dormitories: profile characteristics, source screening, and estimated gas-phase concentration and dermal exposure comparison.

Recently, phthalate exposure has become a major public health concern. However, gaps still remain in our understanding of phthalate profile characteristics, source screening, and gas-phase estimation. This study measured phthalate concentrations in dust and window films in 101 dormitories at 13 universities in Beijing, China, from October to December 2019. Based on the phthalate concentrations in the dust and window films, we estimated the gas-phase phthalate concentrations using steady-state and instantaneous equilibrium models, respectively, and male and female students' dermal exposure using the Monte Carlo simulation. Commonly used materials and supplies were screened for phthalate sources and evaluated using the positive matrix factorization (PMF) model. The results showed that the detection frequency of ten phthalates ranged from 79.2 to 100% in dust and from 84.2 to 100% in window films. Dicyclohexyl phthalate (DCHP), di-(2-ethylhexyl) phthalate (DEHP), and dibutyl phthalate (DBP) were the most abundant phthalates in both indoor media and were also predominant in the indoor materials and supplies. The PMF results indicated that the potential sources of phthalates in dust and window films had both similarities and differences. Indoor door seals, paint, coatings, cables, air-conditioning rubber cable ties, wallpaper, and window seals were highly probable sources of phthalates. The gas-phase phthalate concentrations estimated using the two methods differed, especially for phthalates with high octanol-air partition coefficients (Koa), varying by 1-2 orders of magnitude. Moreover, compared with related studies, the gas-phase concentrations were significantly underestimated for phthalates with high Koa values, while the estimated gas-phase concentrations of phthalates with low Koa values were closer to the measured values. The estimated dermal exposure using the two methodologies also considerably differed. Such findings suggest that more attention should be focused on the exposure risk from the dust phase and window film phase phthalates.

Replacing Plastic with Bamboo: A Review of the Properties and Green Applications of Bamboo-Fiber-Reinforced Polymer Composites.

Natural fiber composites are receiving more and more attention because of their greenness and low cost. Among natural fibers, bamboo is characterized by fast growth, a short cultivation period, high strength and good toughness, and is one of the strongest natural fibers in the world. A bamboo-fiber-reinforced polymer composite (BFRPC) has the characteristics of high mechanical strength, low density, degradability, etc. It has the industrial applicability comparable to metal materials, the same strong corrosion resistance as composites such as glass and carbon fibers, and the same immunity to electromagnetic interference and low thermal conductivity as natural materials. Its unidirectional specific strength and unidirectional specific modulus is higher than that of glass fiber, second only to the extremely high price of carbon fiber, which is playing an increasingly important role in the field of composite materials, and can be widely used in the fields of wind power, construction, aviation, automotive, medical care and so on. At present, it has been initially used in packaging, automotive and transportation fields, and is expected to replace petroleum-based plastics in various fields. In addition to their environmental protection and green production, they have excellent physical properties. This paper provides an overview of the mechanical properties of bamboo-fiber-reinforced thermoplastic composites and thermoset composites that have been developed so far, such as tensile strength, flexural properties and impact strength. In addition, the prospects of bamboo-fiber-reinforced thermoplastic composites for automotive, packaging and agricultural applications are presented.

Nitrate dynamics and source apportionment on the East China Sea shelf revealed by nitrate stable isotopes and a Bayesian mixing model.

The excess input of nitrate is one of the primary factors triggering nearshore eutrophication. To estimate the source apportionment of nitrate on the East China Sea (ECS) shelf, the nitrogen and oxygen stable isotopes in nitrate (δ15N-NO3- and δ18O-NO3-) collected in winter and late spring 2016 were analyzed alongside essential physical, chemical and biological parameters. The temporal and spatial distributions and characteristic values of nitrate-bearing water masses were presented. Accordingly, the end-member mixing model and Rayleigh model were applied to systematically analyze biogeochemical processes. The biogeochemical processes of nitrate were weak in winter, except in the southern ECS, where assimilation and nitrification probably occurred. In contrast, the biogeochemical processes were intensive in spring. The stable isotopic fractionations of N and O were unified in the whole area, and the ratio between δ18O-NO3- and δ15N-NO3- was 1.81 ± 0.04, which indicated significant assimilation accompanying nitrification in spring. Furthermore, a Bayesian stable isotope mixing model was used to reveal the source contributions of nitrate on the ECS shelf for the first time, demonstrating that the Changjiang Diluted Water and Kuroshio Subsurface Water were always sustained and provided steady nitrate sources for the whole ECS. The nitrate inputs from the Yellow Sea to the northern ECS increased from approximately 30 % in spring to nearly 70 % in winter, while that from the Taiwan Strait Warm Water to the southern ECS decreased from approximately 40 % in spring to zero in winter. Moreover, although the nitrate contributions from nitrification were significantly weak in the middle and northern ECS during winter, they were important over the entire ECS during spring. This study qualitatively and quantitatively improves the understanding of seasonal nitrate control from various sources, and these findings are important for nutrient management and policy making to mitigate nearshore eutrophication.

Hypoxia formation in the East China Sea by decomposed organic matter in the Kuroshio Subsurface Water.

Although internal decomposition of organic matter (OM) in the Kuroshio Subsurface Water (KSSW) is a crucial factor for hypoxia formation in the East China Sea (ECS), the seasonal source and contributions of this OM remain debated. This study applied datasets collected in June and October 2015 to discuss these issues qualitatively and quantitatively. According to the variations in several parameters along the KSSW route, N2 fixation signals related to decomposed OM were apparent in the southern ECS during June, while terrestrial input signals were revealed in the northern ECS during June and most of the ECS during October. The terrestrial input contributed 47% of the decomposed OM near the historic hypoxic area in June, indicating that the terrestrial and marine sources contributed almost equally to the development of ECS hypoxia. These results provide vital information for understanding the mechanism of hypoxia formation driven by eutrophication and oceanic circulation.

Heterogeneity of the sediment oxygen demand and its contribution to the hypoxia off the Changjiang estuary and its adjacent waters.

The severe hypoxia off the Changjiang estuary (CE) has a dual-core structure, and the two hypoxic zones exhibit behavioural, physical and biochemical differences. Currently, few studies have revealed straightforward differences regarding the key biochemical processes between these two hypoxic zones. In this study, the phytoplankton sinking rate (PSR) and sediment oxygen demand (SOD) were measured by field experiments and compared between the two hypoxic regions. PSR and SOD ranged from 0.75-3.34 m day-1 and 5.67-16.19 mmol m-2 day-1, respectively. Interestingly, PSR and SOD were higher in the southern region than in the northern region, implying stronger pelagic-benthic biogeochemical coupling in the southern region. SOD accounted for approximately 44% and 51% of DO net consumption in the northern and southern regions, respectively, from July to August. The southern hypoxic region appeared to exhibit intense DO consumption and fast DO supplementation, while the northern hypoxic region seemed to exhibit slow DO consumption and supplementation.

Visible-Light-Driven Ag-Modified TiO2 Thin Films Anchored on Bamboo Material with Antifungal Memory Activity against Aspergillus niger.

A round-the-clock photocatalyst with energy-storage ability has piqued the interest of researchers for removing microbial contaminants from indoor environments. This work presents a moderate round-the-clock method for inhibiting the growth of fungus spores on bamboo materials using Ag-modified TiO2 thin films. Photoactivated antifungal coating with catalytic memory activity was assembled on a hydrophilic bamboo by first anchoring anatase TiO2 thin films (TB) via hydrogen bonding and then decorating them with Ag nanoparticles (ATB) via electrostatic interactions. Antifungal test results show that the Ag/TiO2 composite films grown on the bamboo surface produced a synergistic antifungal mechanism under both light and dark conditions. Interestingly, post-illumination catalytic memory was observed for ATB, as demonstrated by the inhibition of Aspergillus niger (A. niger) spores, in the dark after visible light was removed, which could be attributed to the transfer of photoexcited electrons from TiO2 to Ag, their trapping on Ag under visible-light illumination, and their release in the dark after visible light was removed. The mechanism study revealed that the immobilized Ag nanoparticles served the role of "killing two birds with one stone": increasing visible-light absorption through surface plasmon resonance, preventing photogenerated electron-hole recombination by trapping electrons, and contributing to the generation of ●O2-and ●OH. This discovery creates a pathway for the continuous removal of indoor air pollutants such as volatile organic compounds, bacteria, and fungus in the day and night time.

Main factors dominating the development, formation and dissipation of hypoxia off the Changjiang Estuary (CE) and its adjacent waters, China.

Hypoxia off the Changjiang Estuary (CE) and its adjacent waters is purported to be the most severe in China, attracting considerable concern from both the scientific community and the general public. Currently, continuous observations of dissolved oxygen (DO) levels covering hypoxia from its appearance to disappearance are lacking. In this study, twelve consecutive monthly cruises (from February 2015 to January 2016) were conducted. The consecutive spatiotemporal variations in hypoxia throughout the annual cycle were elucidated in detail, and the responses of annual variations in hypoxia to the different influential factors were explored. Overall, hypoxia experienced a consecutive process of expanding from south to north, then disappearing from north to south. The annual variations in hypoxia were mainly contingent on stratification variations. Among different stages, there was significant heterogeneity in the dominant factors. Specifically, low-DO waters initially appeared from the intrusion of nearshore Kuroshio branch current (NKBC), as NKBC intrusion provided a low-DO background and triggered stratification. Thereafter, stratification was enhanced and gradually expanded northward, which promoted the extension of low-DO areas. The formation of hypoxia was regionally selective, and more intense organic matter decomposition at local regions facilitated the occurrence and discontinuous distribution of hypoxia. Hypoxic zones were observed at the Changjiang bank and Zhejiang coastal region from August (most extensively at 14,800 km2) to October. Thereafter, increased vertical mixing facilitated the dissipation of hypoxia from north to south.

The Effects of Modified Clay on Abalone (Haliotis discus hannai) Based on Laboratory and Field Experiments.

The abalone industry has suffered immense economic losses due to the occurrence of harmful algal blooms (HABs). Among the methods for mitigating HABs, modified clay is considered the most promising strategy and has been successfully used for field applications in many countries, and its environmental effects have become a subject of global concern. The effects of modified clay on the survival, growth, nutritional quality, and oxidative stress indicators of abalone were studied based on both laboratory and field experiments. The results showed that modified clay at 3-10 times the concentrations used for HAB treatment did not affect the survival of abalone. During the laboratory experiments, the increases in abalone shell length and weight nonsignificantly decreased with increasing concentrations of modified clay at 1-15 d, whereas the weight of abalone in the experimental groups increased rapidly during the recovery period at 16-30 d. The growth and nutrition qualities of abalone in field experiments showed negligible differences between the control and experimental groups. Catalase (CAT) activity in the hepatopancreas and superoxide dismutase (SOD) activity in the gills were significantly affected by certain concentrations of modified clay at individual time points, whereas the malondialdehyde (MDA) content decreased in all experimental groups within 96 h. The removal of bacteria and the mitigation of water quality decline were among the effects of modified clay that contributed to the decrease in MDA content. The present study showed that modified clay had no obvious adverse effects on the survival, growth, quality, or oxidative stress indicators of abalone at the experimental concentrations, thus providing a reference for the field application of modified clay in typical aquaculture areas. Environ Toxicol Chem 2020;39:2065-2075. © 2020 SETAC.

In Situ Formation of Ag Nanoparticles in Mesoporous TiO2 Films Decorated on Bamboo via Self-Sacrificing Reduction to Synthesize Nanocomposites with Efficient Antifungal Activity.

We developed a novel green approach for the in situ fabrication of Ag NPs in mesoporous TiO2 films via the bamboo self-sacrificing reduction of Ag(NH3)2+ ions, which can inhibit fungal growth on the bamboo surface. Mesoporous anatase TiO2 (MT) films were first synthesized on bamboo via a hydrothermal method. Then, Ag NPs with a 5.3 nm mean diameter were incorporated into the pore channels of optimal MT/bamboo (MTB) samples at room temperature without the addition of reducing agents, such that the Ag NPs were almost entirely embedded into the MT films. Our analysis indicated that the solubilized lignin from bamboo, which is rich in oxygen-containing functional groups, serves as a green reductant for reducing the Ag(NH3)2+ ions to Ag NPs. Antifungal experiments with Trichoderma viride under dark conditions highlighted that the antifungal activity of the Ag/MT/bamboo samples were greater than those of naked bamboo, MTB, and Ag/bamboo, suggesting that these hybrid nanomaterials produce a synergistic antifungal effect that is unrelated to photoactivity. The inhibition of Penicillium citrinum effectively followed a similar trend. This newly developed bamboo protection method may provide a sustainable, eco-friendly, and efficient method for enhancing the antifungal characteristics of traditional bamboo, having the potential to prolong the service life of bamboo materials, particularly under dark conditions.

Flame retardant and visible light-activated Fe-doped TiO2 thin films anchored to wood surfaces for the photocatalytic degradation of gaseous formaldehyde.

Flame retardant and visible light-activated Fe-doped TiO2 thin films were anchored to wood surfaces by a facile precipitation method for the photocatalytic degradation of gaseous formaldehyde. All of the as-prepared TiO2 thin films exhibited the anatase crystal structure and grew on the wood surfaces by the aggregation of nanoparticles with diameters ranging from 11 to 16 nm. The UV-vis diffuse reflectance spectroscopy (UV-vis DRS) results showed that the presence of a small amount of iron ions in the TiO2 matrix could significantly extend the optical responses in the UV to visible region. Compared to the pure TiO2/wood samples, the Fe-doped TiO2/wood samples exhibited higher photocatalytic activities under visible light irradiation. The optimum nFe/nTi molar ratio was 2.0 at. %. The electron spin resonance (ESR) tests further confirmed that the active oxygen species of OH and O2- that were generated on the Fe-doped TiO2/wood samples under visible light irradiation are responsible for the degradation of formaldehyde. The Fe-doped TiO2 samples also exhibited high stability and reusability after 6 cycles. Additionally, the limiting oxygen index of the original wood increased from 24.8% to 33.9% after it was coated with Fe-doped TiO2 thin films, indicating a significant improvement in its flame resistance.