Pyrrolizidine alkaloids (PAs) are common phytotoxins. We performed the first comprehensive investigation on PA contamination in Chinese honeys. LC-MS analysis revealed that 58% of 255 honey samples purchased from 17 regions across Mainland China and Taiwan contained PAs with total content ranging over 0.2–281.1 μg/kg. Monocrotaline (from Crotalaria spp), a PA never found in honey in other regions, together with echimidine (Echium plantagineum) and lycopsamine (from Senecio spp.), were three predominant PAs in PA-contaminated Chinese honeys. Further, PAs present in honeys were found to have geographically distinct pattern, indicating possible control of such contamination in future honey production. Moreover, we proposed a new risk estimation approach, which considered both content and toxic potency of individual PAs in honeys, and found that 12% of the PA-contaminated Chinese honeys tested might pose potential health risk. This study revealed a high prevalence and potential health risk of PA contamination in Chinese honeys.

This study examined the long-term trends in chemical components in PM₂.₅ (particulate matter with aerodynamic diameter ≤2.5 μm) samples collected at Lulin Atmospheric Background Station (LABS) located on the summit of Mt. Lulin (2862 m above mean sea level) in Taiwan in the western North Pacific during 2003–2018. High ambient concentrations of PM₂.₅ and its chemical components were observed during March and April every year. This enhancement was primarily associated with the long-range transport of biomass burning (BB) smoke emissions from Indochina, as revealed from cluster analysis of backward air mass trajectories. The decreasing trends in ambient concentrations of organic carbon (−0.67% yr⁻¹; p = 0.01), elemental carbon (−0.48% yr⁻¹; p = 0.18), and non–sea-salt (nss) K⁺ (−0.71% yr⁻¹; p = 0.04) during 2003–2018 indicated a declining effect of transported BB aerosol over the western North Pacific. These findings were supported by the decreasing trend in levoglucosan (−0.26% yr⁻¹; p = 0.20) during the period affected by the long-range transport of BB aerosol. However, NO₃⁻ displayed an increasing trend (0.71% yr⁻¹; p = 0.003) with considerable enhancement resulting from the air masses transported from the Asian continent. Given that the decreasing trends were for the majority of the chemical components, the columnar aerosol optical depth (AOD) also demonstrated a decreasing trend (−1.04% yr⁻¹; p = 0.0001) during 2006–2018. Overall decreasing trends in ambient (carbonaceous aerosol and nss-K⁺) as well as columnar (e.g., AOD) aerosol loadings at the LABS may influence the regional climate, which warrants further investigations. This study provides an improved understanding of the long-term trends in PM₂.₅ chemical components over the western North Pacific, and the results would be highly useful in model simulations for evaluating the effects of BB transport on an area.

Organic carbon (OC) can help control greenhouse gas emissions by participating in biogeochemical reactions and preventing the migration of contaminants in groundwater systems. The association of OC with Fe (Iron) oxide minerals plays a significant role in stabilizing OC and regulating the biogeochemical cycles of OC on the earth’s surface. Reclaiming farmland from lakes changes an original lake into a wetland, but the destiny of Fe bound-OC in the underlying aquitard during this process has been poorly understood. The mechanisms of migration and transformation of Fe bound-OC were investigated in subsurface aquitard sediments of three typical boreholes in the Chen Lake wetland, central China. The Fe bound-OC content in the natural sedimentary conditions (borehole A), transition area (borehole B), and intensive reclamation area (borehole C) were 0.17–3.87, 0.28–3.98 and 0.13–7.08 mg g⁻¹, respectively. The reclamation changed the redox, water, and infiltration conditions of the surface environment, resulting in a transformation of Fe oxides phases, and then cause the change of content and structure of Fe bound-OC. The fresh organic matter provided by undecomposed crops causes oxygen- and nitrogen-rich compounds to combine with Fe oxides extensively through adsorption, resulting in higher δ¹³C values of Fe bound-OC than non-Fe bound-OC. Fe bound-OC has strong resistance to biodegradation. The Fe bound-OC: total OC ratios generated by adsorption and coprecipitation on the surface layer (0 to −3.5 m) of borehole C was 10.37% and 18.86%, 6.92% and 12.46% higher than those of boreholes A and B, respectively. Coprecipitation has a stronger OC-binding ability and enriches more carboxylates and aromatics, while adsorption gradually assumed a dominant position in OC-Fe interaction in deep aquitard. The reduction dissolution of Fe oxide causes Fe bound-OC to transfer into pore water, leading to an increase of Fe ion and dissolved OC in deep strata.

We apply convolutional neural network (CNN) model for estimating daily 24-h averaged ground-level PM2.5 of the conterminous United States in 2011 by incorporating aerosol optical depth (AOD) data, meteorological fields, and land-use data. Unlike some of the recent supervised learning-based approaches, which only utilized the predictors from the location of which PM2.5 value is estimated, we naturally aggregate predictors from nearby locations such that the spatial correlation among the predictors can be exploited. We carefully evaluate the performance of our method via overall, temporally-separated, and spatially-separated cross-validations (CV) and show that our CNN achieves competitive estimation accuracy compared to the recently developed baselines. Furthermore, we develop a novel predictor importance metric for our CNN based on the recent neural network interpretation method, Layerwise Relevance Propagation (LRP), and identify several informative predictors for PM2.5 estimation.

Recently, chemical compounds containing lanthanides were used in various fields of biology and medicine. It has been described that such compounds can be applied in scanning electron microscopy (SEM) to increase the contrast and simplify the sample preparation process due to the process of replacing calcium with lanthanides in cell. However cell death by different mechanisms under influence of lanthanides seems possible. Here, we described that mummification process is a cell death physiologically realized in time: some time after lanthanide contrasting, the cell remains metabolically active and is able to biochemically transform neodymium-containing contrast, oxidize it and form large agglomerates. A distinctive feature of mummification induced by neodymium-containing contrast (NCC) is the formation of a high-rigid oxygen-containing “shield” on the surface of a neutrophil granulocyte.

In situ immobilization of heavy metals in contaminated soils using industrial by-products is an attractive remediation technique. In this work, titanium gypsum (TG) was applied at two levels (TG-L: 0.15% and TG-H: 0.30%) to simultaneously reduce the uptake of cadmium (Cd), lead (Pb) and arsenic (As) in rice grown in heavy metal contaminated paddy soils. The results showed that the addition of TG significantly decreased the pH and dissolved organic carbon (DOC) in the bulk soil. TG addition significantly improved the rice plants growth and reduced the bioavailability of Cd, Pb and As. Particularly, bioavailable Cd, Pb and As decreased by 35.2%, 38.1% and 38.0% in TG-H treatment during the tillering stage, respectively. Moreover, TG application significantly reduced the accumulation of Cd, Pb and As in brown rice. Real-time PCR analysis demonstrated that the relative abundance of sulfate-reducing bacteria increased with the TG application, but not for the iron-reducing bacteria. In addition, 16S rRNA sequencing analysis revealed that the relative abundances of heavy metal-resistant bacteria such as Bacillus, Sulfuritalea, Clostridium, Sulfuricella, Geobacter, Nocardioides and Sulfuricurvum at the genus level significantly increased with the TG addition. In conclusion, the present study implied that TG is a potential and effective amendment to immobilize metal(loid)s in soil and thereby reduce the exposure risk of metal(loid)s associated with rice consumption.

To compare aquatic organisms’ responses to the toxicity of copper oxide (CuO) nanoparticles (NPs) with those of CuO microparticles (MPs) and copper (Cu) ions, a global metabolomics approach was employed to investigate the changes of both polar and nonpolar metabolites in microalga Chlorella vulgaris after 5-day exposure to CuO NPs and MPs (1 and 10 mg/L), as well as the corresponding dissolved Cu ions (0.08 and 0.8 mg/L). Unchanged growth, slight reactive oxygen species production, and significant membrane damage (at 10 mg/L CuO particles) in C. vulgaris were demonstrated. A total of 75 differentiated metabolites were identified. Most metabolic pathways perturbed after CuO NPs exposure were shared by those after CuO MPs and Cu ions exposure, including accumulation of chlorophyll intermediates (max. 2.4–5.2 fold), membrane lipids remodeling for membrane protection (decrease of phosphatidylethanolamines (min. 0.6 fold) and phosphatidylcholines (min. 0.2–0.7 fold), as well as increase of phosphatidic acids (max. 1.5–2.9 fold), phosphatidylglycerols (max. 2.2–2.3 fold), monogalactosyldiacylglycerols (max. 1.2–1.4 fold), digalactosylmonoacylglycerols (max. 1.9–3.8 fold), diacylglycerols (max. 1.4 fold), lysophospholipids (max. 1.8–3.0 fold), and fatty acids (max. 3.0–6.2 fold)), perturbation of glutathione metabolism induced by oxidative stress, and accumulation of osmoregulants (max. 1.3–2.6 fold) to counteract osmotic stress. The only difference between metabolic responses to particles and those to ions was the accumulation of fatty acids oxidation products: particles caused higher fold changes (particles/ions ratio 1.9–3.0) at 1 mg/L and lower fold changes (particles/ions ratio 0.4–0.7) at 10 mg/L compared with ions. Compared with microparticles, there was no nanoparticle-specific pathway perturbed. These results confirm the predominant role of dissolved Cu ions on the toxicity of CuO NPs and MPs, and also reveal particle-specific toxicity from a metabolomics perspective.

The potential risks of phthalates affecting human and animal health as well as the environment are emerging as serious concerns worldwide. However, the mechanism by which phthalates induce developmental effects is under debate. Herein, we found that embryonic exposure of zebrafish to di-(2-ethylhexyl) phthalate (DEHP) and di-butyl phthalate (DBP) increased the rate of heart defects including abnormal heart rate and pericardial edema. Changes in the transcriptional profile demonstrated that genes involved in the development of the heart, such as tbx5b, nppa, ctnt, my17, cmlc1, were significantly altered by DEHP and DBP at 50 μg/L, which agreed with the abnormal cardiac outcomes. Methylated DNA immunoprecipitation sequencing (MeDIP-Seq) further showed that significant hypomethylation of nppa and ctnt was identified after DEHP and DBP exposure, which was consistent with the up-regulation of these genes. Notably, hypermethylation on the promoter region (<1 kb) of tbx5b was found after DEHP and DBP exposure, which might be responsible for its decrease in transcription. In conclusion, phthalates have the potential to induce cardiac birth defects, which might be associated with the transcriptional regulation of the involved developmental factors such as tbx5b. These findings would contribute to understand the molecular pathways that mediated the cardiac defects caused by phthalates.

Evaluating speciation of arsenic (As) is essential to assess its risk in paddy soils. In this study, effects of phosphate on speciation of As in six paddy soils differing in redox status were studied over a range of pH (pH 3-9) and different background calcium (Ca) levels by batch adsorption experiments and speciation modeling. Contrasting effects of phosphate on As speciation were observed in suboxic and anoxic soils. Under suboxic conditions, phosphate inhibited Fe and As reduction probably due to stabilization of Fe-(hydr)oxides, but increased soluble As(V) concentration as a result of competitive adsorption between As(V) and phosphate. In anoxic soils, phosphate stimulated Fe and As reduction and caused increases of As(III) in soil solution under both acidic and neutral/alkaline pH. The LCD (Ligand and Charge Distribution) and NOM-CD (Natural Organic Matter-Charge Distribution) model can describe effects of pH, calcium and phosphate on As speciation in these paddy soils. The results suggest that phosphatefertilization may decrease (at low pH) or increase (at neutral/alkaline pH) As mobility in paddy soils under (sub)oxic conditions, but under anoxic conditions and in phosphorus deficient soils phosphate fertilization may strongly mobilize As by promoting microbial activities.