Spiramycin is a widely used macrolide antibiotic and exists at high concentration in production wastewater. A thermal-acid hydrolytic pretreatment using silicotungstic acid (STA) under microwave (MW) irradiation was suggested to mitigate spiramycin from production wastewater. Positive correlations were observed between STA dosage, MW power, interaction time and the hydrolytic removal efficiencies, and an integrative equation was generalized quantitively. Rapid and complete removal 100 mg/L of spiramycin was achieved after 8 min of reaction with 1.0 g/L of STA under 200 W of MW irradiation, comparing to 30.1% by MW irradiation or 15.9% by STA alone. The synergetic effects of STA and MW irradiation were originated from the dissociated-proton catalysis by STA and the dipolar rotation heating effect of MW. STA performed much better than the mineral acid H2SO4 under MW, due to the much stronger Brönsted acidity and higher Hammett acidity. After 8 min, 98.0% of antibacterial potency was also reduced. The m/z 558.8614 fragment (P1) and m/z 448.1323 fragment (P2) were identified as the primary products, which were formed by breaking glucosidic bonds and losing mycarose and forosamine for P1 and further mycaminose moiety for P2. Finally, production wastewater with 433 mg/L of spiramycin was effectively treated using this thermal-acid hydrolytic method. Spiramycin and its antibacterial potency both dropped to 0 after 6 min. The potency drop was supposed from the losing of mycarose and/or forosamine. To decrease both the concentration of spiramycin and its antibacterial potency, combinedly using STA and MW was suggested in this work to break down the structural bonds of the functional groups rather than to destroy the whole antibiotic molecules. It is promising for pretreating spiramycin-contained production wastewater to mitigate both the antibiotic and its antibacterial potency.

Rapid industrialization in China during the last three decades has resulted in widespread contamination of Cd in agricultural soils. A considerable proportion of the rice grain grown in some areas of southern China has Cd concentrations exceeding the Chinese food limit, raising widespread concern regarding food safety. In this review, we summarize rice grain Cd concentrations in national Chinese markets and in field surveys from contaminated areas, and analyze the potential health risk associated with increased dietary Cd intake. For subsistence rice farmers living in some contaminated areas of southern China who mainly consume locally-produced Cd-contaminated rice, their estimated dietary Cd intake is now comparable to that for the population in the region of Japan where the Itai-Itai disease was first reported. Interventions must be taken urgently to reduce Cd intake for these farmers. We also analyze i) the main reasons causing elevated grain Cd concentrations in southern China, ii) the dominant biogeochemical processes controlling the solubility of Cd in paddy soils, and iii) molecular mechanisms for the uptake and translocation of Cd in rice plants. Based on these analyses, we propose a number of countermeasures to address soil Cd contamination, including i) mitigation of Cd transfer from paddy soils to rice grain, and ii) intervention in those farmers who consume home-grown Cd-contaminated rice. Liming to increase soil pH to 6.5 and gene editing biotechnology are effective strategies to decrease Cd accumulation in rice grain. For these local farmers with high-Cd exposure risk, local governments should monitor the Cd concentration in their home-grown rice and exchange those high-Cd rice with low-Cd rice in order to reduce their dietary Cd intake.

Elemental concentrations of ambient aerosols are commonly sampled over 12–24 h, and the low time resolution puts a great limit on current understanding about the temporal variations and source apportionment based on receptor models. In this work, hourly-resolved concentrations of eighteen elements in PM₂.₅ at an urban site in Nanjing, a megacity in Yangtze River Delta of east China, were obtained by using a Xact 625 ambient metals monitor from 12/12/2016 to 12/31/2017. The influence of traffic activities was clearly reflected by the spikes of crustal elements (e.g., Fe, Ca, and Si) in the morning rush hour, and the firework burning and sandstorm events during the sampling periods were tracked by sharp enrichment of Ba, K and Fe, Ca, Si, Ti in PM₂.₅, respectively. To evaluate the advantage of hourly-resolved elements data in identifying impacts from specific emission sources, positive matrix factorization (PMF) analysis was performed with the 1-h data set (PMF₁₋ₕ) and 23-h averaged data (PMF₂₃₋ₕ), respectively. The 4- and 6-factor PMF₂₃₋ₕ solutions had similar factor profiles and consistent factor contributions as the corresponding PMF₁₋ₕ solutions. However, due to the limit in inter-sample variability, PMF analysis with 23-h average data misclassified some major (e.g., K, Fe, Zn, Ca, and Si) and trace (e.g., Pb) elements in factor profiles, resulting in different absolute factor contributions between PMF₂₃₋ₕ and PMF₁₋ₕ solutions. These results suggested the use of high time-resolved data to obtain valid and robust source apportionment results.

Population growth, urbanization, environmental conditions and rapid development have caused particulate matter (PM) levels to rise above all national and international health standards during the last two decades in many South-East Asian countries. These PM levels needs to be reduced urgently as they increase the risk of cardiovascular and respiratory health problems for millions of people. Plants have shown to efficiently reduce PM in the air by accumulation on their leaves. In order to investigate which plant species accumulate most PM, we screened 49 common plant species for their PM accumulation capacity in one of the tropical cities with the highest PM concentrations of the world, Hanoi (Vietnam). Using this subset of plants, we tested if certain leaf characteristics (leaf hydrophilicity, stomatal densities and the specific leaf area) can predict the PM accumulation efficiency of plant species. Our results show that the PM accumulation capacity varies substantially among species and that Muntingia calabura accumulated most PM in our subset of plants. We observed that plants with hydrophilic leaves, a low specific leaf area and a high abaxial stomatal density accumulated significantly more PM. Plants with these characteristics should be preferred by urban architects to reduce PM levels in tropical environments.

The N-TiO2/g-C3N4@diatomite (NTCD) composite has been prepared through a simple impregnation method, using titanium tetrachloride as precursor and urea as nitrogen-carbon source. Then the effects of calcination temperature on structure, surface property and photocatalytic activity of the catalysts were investigated. And XRD, TEM, XPS, FTIR and UV–vis diffuse adsorption spectroscopy were used to characterize the obtained powders. The photocatalytic activity of the NTCD was evaluated through the reduction of aqueous Cr (VI) under visible light irradiation (λ > 400 nm). The results demonstrated that the nano-TiO2 particles ranging from 15 to 30 nm in the crystal of anatase are well deposited on the surface of diatomite in the NTCD-500 which calcined at 500 °C for 2 h. Furthermore, the g-C3N4 with the lay thickness of 0.92 nm was attached to the surface of nano-TiO2. The N-doped TiO2 and g-C3N4 doped catalysts could co-enhance response in the visible light region and reduce band gap of NTCD-500 (Eg = 3.07 eV). And the NTCD-500 sample exhibited nearly 100% removal rate within 5 h for photocatalytic reduction of Cr (VI) which was higher activity than P25, crude TiO2@diatomite and g-C3N4@diatomite.

Microplastic (MP) pollution is everywhere. In terrestrial environments, microfibres (MFs) generated from textile laundering are believed to form a significant component of MPs entering soils, mainly through sewage sludge and compost applications. The aim of this study was to assess the effect of MFs on a keystone soil organism. We exposed the earthworm Lumbricus terrestris to soil with polyester MFs incorporated at rates of 0, 0.1 and 1.0 %w/w MF for a period of 35 days (in the dark at 15 °C; n = 4 for each treatment). Dried plant litter was applied at the soil surface as a food source for the earthworms. We assessed earthworm vitality through mortality, weight change, depurate production and MF avoidance testing. In addition, we measured stress biomarker responses via the expression of metallothionein-2 (mt-2), heat shock protein (hsp70) and superoxide dismutase (sod-1). Our results showed that exposure and ingestion of MFs (as evidenced by subsequent retrieval of MFs within earthworm depurates) were not lethal to earthworms, nor did earthworms actively avoid MFs. However, earthworms in the MF1.0% treatment showed a 1.5-fold lower cast production, a 24.3-fold increase in expression of mt-2 (p < 0.001) and a 9.9-fold decline in hsp70 expression (p < 0.001). Further analysis of soil and MF samples indicated that metal content was not a contributor to the biomarker results. Given that burrowing and feeding behaviour, as well as molecular genetic biomarkers, were modulated in earthworms exposed to MFs, our study highlights potential implications for soil ecosystem processes due to MF contamination.

Aluminum is a widely distributed metal that has been reported to have embryotoxicity and fetotoxicity in animal studies. However, there has been no study of the association between prenatal aluminum exposure and newborn mitochondrial DNA copy number (mtDNAcn). We aimed to investigate the effect of prenatal aluminum exposure on newborn mtDNAcn. A total of 762 mother-newborn pairs were recruited between November 2013 and March 2015 in Wuhan city, China. We measured maternal urinary aluminum concentrations at three trimesters of pregnancy. Relative mtDNAcn was measured in DNA extracted from umbilical cord blood samples. We used generalized estimating equations to assess the relationship between prenatal aluminum exposure and newborn mtDNAcn. The geometric means of creatinine corrected aluminum concentrations were 31.0 μg/g Cr (95% CI: 27.6, 34.7), 40.9 μg/g Cr (95% CI: 35.7, 46.8) and 58.4 μg/g Cr (95% CI: 51.2, 67.4) for the first, second and third trimesters, respectively. After adjustment for potential confounding factors, a doubling of maternal urinary aluminum concentrations during the second and third trimesters was related to 3.16% (95% CI: 0.88, 5.49) and 4.20% (95% CI: 1.64, 6.81) increases in newborn mtDNAcn, respectively, while the association between maternal urinary aluminum concentration during the first trimester and newborn mtDNAcn was not significant (percent difference: 0.70%, 95% CI: −2.25, 3.73). Prenatal aluminum exposure during the second and third trimesters was positively associated with newborn mtDNAcn. Further studies are essential to elucidate on the potential health consequences of newborn mtDNAcn.

Current air quality models usually underestimate the concentration of ambient air sulfate, but the cause of this underestimation remains unclear. One reason for the underestimation is that the sulfate formation mechanism in the models is incomplete, and does not adequately consider the impact of the synergistic effects of high concentrations of multiple pollutants on sulfate formation. In this work, the roles of gaseous NO₂, NH₃ and solution ionic strength in the formation of sulfate in the aqueous phase were quantitatively investigated using a glass reactor and a 30 m³ smog chamber, separately. The results showed that sulfate formation was enhanced to different degrees in the presence of gas-phase NO₂, NH₃ and their coexistence as solutes in both liquid solution and aerosol water. NH₃ enhances the aqueous oxidation of SO₂ by NO₂ mainly by accelerating the uptake of SO₂ through increased solubility. More importantly, we found that high ionic strength in aerosol water could significantly accelerate the aqueous oxidation of SO₂, resulting in unexpectedly high S(VI) formation rates. We estimate that under severe haze conditions, heterogeneous oxidation of SO₂ by NO₂ on aerosols may be much shorter than that through gas phase oxidation by OH, aided by high ionic strengths in aerosols. Considering the existence of complex air pollution conditions with high concentrations of NO₂, NH₃ and aerosol water, as expected in typical urban and suburban settings, the sulfate formation mechanisms revealed in the present work should be incorporated into air quality models to improve the prediction of sulfate concentrations.

Marine polychaetes and fish are known to ingest polystyrene microparticles in the environment. Laboratory microplastic feeding experiments have demonstrated that plastic may release endocrine-disrupting compounds such as diethylhexyl phthalate (DEHP), which can cause adverse effects in both vertebrates and invertebrates. In order to determine the influence of size and digestive conditions on the desorption of DEHP and other plasticizers to polychaetes and fish, we exposed polystyrene particles of various sizes under invertebrate and vertebrate digestive conditions (vertebrate mimic; pepsin, pH = 2.0, 24 °C, invertebrate mimic; Na taurocholate pH = 7, 18 °C). Estrogen receptor activation and concentrations of 12 plasticizers were measured in the extracts. DEHP, bisphenol S and 4-tert-octylphenol were the only compounds detected. Simulated vertebrate gut digestion did not significantly enhance the release of chemicals nor estrogenic activity. However, a 6.3 ± 2.0-fold increase in the concentration of DEHP was observed in extracts from invertebrate gut conditions (Mean ± SD; N = 24, p < 0.0001). Additionally, estimated particle surface area was positively correlated with estrogenic activity across all treatment types (r = 0.85, p < 0.0001). Overall, these data indicate an elevated bioaccessibility of DEHP may occur in invertebrates, and size-dependent desorption of uncharacterized estrogenic compounds from plastic suggest additional complexity when considering the risks of MP to aquatic organisms.