Polychlorinated diphenyl ethers (PCDEs) are typical halogenated aromatic pollutants that have shown various toxicological effects on organisms. However, the contamination status of PCDEs in the fresh water lakes of China remains poorly researched. In this study, the levels of 15 congeners of PCDEs in the sediments, suspended particulate matter (SPM) and water of Chaohu Lake were determined. The results showed that the ranges of concentrations of total PCDEs (ΣPCDEs) in the sediment, SPM and water were 0.279 ng g−1 dry weight (d.w.)–2.474 ng g−1 d.w., 0.331 ng g−1 d.w.–2.013 ng g−1 d.w. and 0.351 ng L−1–2.021 ng L−1, respectively. The most abundant congeners found in sediments, SPM and water were 3,3′,4,4′-tetra-CDE, deca-CDE and 2,4,6-tri-CDE, with average contributive ratios of 17.36%, 15.48% and 20.63%, respectively. The medium and higher chlorinated PCDEs (e.g., penta- and deca-CDEs) were the dominant congeners in sediments and SPM. The percentages of lower chlorinated PCDEs (e.g., tri-CDEs) in the water were higher than those in the sediments. The combined input of ΣPCDEs from the eight main tributaries to Chaohu Lake was estimated at 6.94 kg y−1. Strong linear correlations between the concentrations of ΣPCDEs and organic carbon (OC) contents in three type samples from Chaohu Lake suggested OC could influence the distribution of PCDEs in Chaohu Lake substantially. In addition, the calculated average organic carbon normalized partition coefficients (logKoc) of 15 PCDEs between water and SPM were in the range of 4.55–5.45 mL g−1. This study confirmed that Chaohu Lake is contaminated by PCDEs.

Selenium (Se) is an essential trace element for humans and animals, although controversial for different plant species. There exists a narrow line between essential, beneficial and toxic levels of Se to living organisms which greatly varies with Se speciation, as well as the type of living organisms. Therefore, it is crucial to monitor its solid- and solution-phase speciation, exposure levels and pathways to living organisms. Consumption of Se-laced food (cereals, vegetables, legumes and pulses) is the prime source of Se exposure to humans. Thus, it is imperative to assess the biogeochemical behavior of Se in soil-plant system with respect to applied levels and speciation, which ultimately affect Se status in humans. Based on available relevant literature, this review traces a plausible link among (i) Se levels, sources, speciation, bioavailability, and effect of soil chemical properties on selenium bioavailability/speciation in soil; (ii) role of different protein transporters in soil-root-shoot transfer of Se; and (iii) speciation, metabolism, phytotoxicity and detoxification of Se inside plants. The toxic and beneficial effects of Se to plants have been discussed with respect to speciation and toxic/deficient concentration of Se. We highlight the significance of various enzymatic (catalase, peroxidase, superoxide dismutase, ascorbate peroxidase, glutathione peroxidase) and non-enzymatic (phytochelatins and glutathione) antioxidants which help combat Se-induced overproduction of reactive oxygen species (ROS). The review also delineates Se accumulation in edible plant parts from soils containing low or high Se levels; elucidates associated health disorders or risks due to the consumption of Se-deficient or Se-rich foods; discusses the potential role of Se in different human disorders/diseases.

A comprehensive study was carried out from central part of Indo-Gangetic Plain (IGP; at Kanpur) to understand abundance, temporal variability, processes (secondary formation and fog-processing) and source-apportionment of PM₁-bound species (PM₁: particulate matter of aerodynamic diameter ≤ 1.0 μm) during wintertime. A total of 50 PM₁ samples were collected of which 33 samples represent submicron aerosol characteristics under non-foggy condition whereas 17 samples represent characteristics under thick foggy condition. PM₁ mass concentration during non-foggy episodes varied from 24–393 (Avg.: 247) μg m⁻³, whereas during foggy condition it ranged from 42–243 (Avg.: 107) μg m⁻³. With respect to non-foggy condition, the foggy conditions were associated with higher contribution of PM₁-bound organic matter (OM, by 23%). However, lower fractional contribution of SO₄²⁻, NO₃⁻ and NH₄⁺ during foggy conditions is attributable to wet-scavenging owing to their high affinity to water. Significant influence of fog-processing on organic aerosols composition is also reflected by co-enhancement in OC/EC and WSOC/OC ratio during foggy condition. A reduction by 5% in mineral dust fraction under foggy condition is associated with a parallel decrease in PM₁ mass concentration. However, mass fraction of elemental carbon (EC) looks quite similar (≈3% of PM₁) but the mass absorption efficiency (MAE) of EC is higher by 30% during foggy episodes. Thus, it is evident from this study that fog-processing leads to quite significant enhancement in OM (23%) contribution (and MAE of EC) with nearly equal and parallel decrease in SO₄²⁻, NO₃⁻ and NH₄⁺ and mineral dust fractions (totaling to 24%). Characteristic features of mineral dust remain similar under foggy and non-foggy conditions; inferred from similar ratios of Fe/Al (≈0.3), Ca/Al (0.35) and Mg/Al (0.22). Positive matrix factorization (PMF) resolves seven sources: biomass burning (19.4%), coal combustion (1.1%), vehicular emission (3%), industrial activities (6.1%), leather tanneries (4%), secondary transformations (46.2%) and mineral dust (20.2%).

With the recent ban of triclosan (TCS) and triclocarban (TCC) from some personal care products, many replacement antimicrobial compounds have been used. Yet the potential health risk and environmental impact of these replacement compounds are largely unknown. Here we investigated the toxicological effects of three commonly used replacement antimicrobials, benzalkonium chloride (BAC), benzethonium chloride (BEC), and chloroxylenol (CX) to two model organisms, the nematode C. elegans and zebrafish (Danio rerio), and compared them to the banned TCS and TCC. We found that these replacement compounds are not any safer than the banned antimicrobials. In the worm, at least one of the three, BAC, showed comparable toxicity to TCS from organismal to molecular levels, with toxic effects occurring at lower hundred μg/L to lower mg/L levels. In the fish, all three compounds at the tested concentration ranges (0.05–5 mg/L) showed toxicity effects to zebrafish embryos, indicated by hatching delay or inhibition, embryonic mortality, morphological malformations, and neurotoxicity. BAC was the most toxic among the three, with acute lethal toxicity occurring at environmentally relevant concentrations (hundreds of μg/L), which is comparable to the banned TCC. However, the toxicity effects of BAC and TCC occurred within different time windows, potentially suggesting different mechanisms of toxicity. CX was the only compound that induced a “body curvature” phenotype among the five compounds examined, suggesting a unique mode of toxic action for this compound. Furthermore, all five compounds except TCS induced neurotoxicity in fish larvae, indicated by alterations in secondary motoneuron axonal projections. Such neurotoxicity has been largely understudied for these antimicrobials in the past years and calls for further investigations in terms of its underlying mechanisms and ecological significance. These findings strongly indicate that scrutiny should be put on these replacement compounds before their introduction into massive use in personal care products.

Pollution by microplastics in aquatic ecosystems is accumulating at an unprecedented scale, emerging as a new surface for biofilm formation and gene exchange. In this study, we determined the permissiveness of aquatic bacteria towards a model antibiotic resistance plasmid, comparing communities that form biofilms on microplastics vs. those that are free-living. We used an exogenous and red-fluorescent E. coli donor strain to introduce the green-fluorescent broad-host-range plasmid pKJK5 which encodes for trimethoprim resistance. We demonstrate an increased frequency of plasmid transfer in bacteria associated with microplastics compared to bacteria that are free-living or in natural aggregates. Moreover, comparison of communities grown on polycarbonate filters showed that increased gene exchange occurs in a broad range of phylogenetically-diverse bacteria. Our results indicate horizontal gene transfer in this habitat could distinctly affect the ecology of aquatic microbial communities on a global scale. The spread of antibiotic resistance through microplastics could also have profound consequences for the evolution of aquatic bacteria and poses a neglected hazard for human health.

Severe and persistent haze accompanied by high concentrations of fine particulate matter (PM₂.₅) has become a great public health concern in urban China. However, research on the health effects of PM₂.₅ in China has been hindered by the lack of high-quality exposure estimates. In this study, we assessed the excess mortality associated with both short- and long-term exposure to ambient PM₂.₅ simultaneously using satellite-derived exposure data at a high spatiotemporal resolution. Adult registries of non-accidental, respiratory and cardiovascular deaths in urban Beijing in 2013 were collected. Exposure levels were estimated from daily satellite-based PM₂.₅ concentrations at 1 km spatial resolution from 2004 to 2013. Mixed Poisson regression models were fitted to estimate the cause-specific mortality in association with PM₂.₅ exposures. With the mutual adjustment of short- and long-term exposure of PM₂.₅, the percent increases associated with every 10 μg/m³ increase in short-term PM₂.₅ exposure were 0.09% (95% CI: −0.14%, 0.33%; lag 01), 1.02% (95% CI: 0.08%, 1.97%; lag 04) and 0.09% (95% CI: −0.23%, 0.42%; lag 01) for non-accidental, respiratory and cardiovascular mortality, respectively; those attributable to every 10 μg/m³ increase in long-term PM₂.₅ exposure (9-year moving average) were 16.78% (95% CI: 10.58%, 23.33%), 44.14% (95% CI: 20.73%, 72.10%) and 3.72% (95% CI: −3.75%, 11.77%), respectively. Both associations of short- and long-term exposure with the cause-specific mortality decreased after they were mutually adjusted. Associations between short-term exposure to satellite-based PM₂.₅ and cause-specific mortality were larger than those estimated using fixed measurements. Satellite-based PM₂.₅ predictions help to improve the spatiotemporal resolution of exposure assessments and the mutual adjustment model provide better estimation of PM₂.₅ associated health effects. Effects attributable to long-term exposure of PM₂.₅ were larger than those of short-term exposure, which should be more concerned for public health.

A green alga, Chlamydomonas reinhardtii, was used to verify whether a simple Biotic Ligand Model (BLM) could be used to predict carefully controlled short-term biouptake for the lanthanide, Nd. In the absence of ligands or competitors, Nd biouptake was well described by a Michaelis-Menten equation with an affinity constant, KNd, of 10⁶.⁸ M⁻¹ and a maximum internalization flux of Jₘₐₓ = 1.70 × 10⁻¹⁴ mol cm⁻² s⁻¹. For bi-metal mixtures containing Nd and Ca, Mg, Sm or Eu, Nd uptake could also be well modelled by assigning experimentally determined affinity constants of KCₐ = 10².⁶ M⁻¹, KMg = 10³.⁴ M⁻¹, KSₘ = 10⁶.⁵ M⁻¹ and KEᵤ = 10⁶.⁵ M⁻¹. The similar values of Kₘ and Jₘₐₓ for the three rare earth elements (REEs): Sm, Eu and Nd is consistent with them sharing a common metal uptake site. On the other hand, in the presence of the small organic ligands (citric or malic acid), neither, free or total Nd concentrations could be used to quantitatively predict Nd internalization fluxes. In other words, in order to predict biouptake by simple BLM determinations, it was necessary to consider that the Nd complexes were bioavailable. The data strongly suggest that risk evaluations of the REE will require a new paradigm and new tools for evaluating bioavailability.

Increased reactive nitrogen (N) loadings to terrestrial ecosystems are believed to have positive effects on ecosystem carbon (C) sequestration. Global “hot spots” of N deposition are often associated with currently or formerly high deposition of sulphur (S); C fluxes in these regions might therefore not be responding solely to N loading, and could be undergoing transient change as S inputs change. In a four-year, two-forest stand (mature Norway spruce and European beech) replicated field experiment involving acidity manipulation (sulphuric acid addition), N addition (NH4NO3) and combined treatments, we tested the extent to which altered soil solution acidity or/and soil N availability affected the concentration of soil dissolved organic carbon (DOC), soil respiration (Rs), microbial community characteristics (respiration, biomass, fungi and bacteria abundances) and enzyme activity. We demonstrated a large and consistent suppression of soil water DOC concentration driven by chemical changes associated with increased hydrogen ion concentrations under acid treatments, independent of forest type. Soil respiration was suppressed by sulphuric acid addition in the spruce forest, accompanied by reduced microbial biomass, increased fungal:bacterial ratios and increased C to N enzyme ratios. We did not observe equivalent effects of sulphuric acid treatments on Rs in the beech forest, where microbial activity appeared to be more tightly linked to N acquisition. The only changes in C cycling following N addition were increased C to N enzyme ratios, with no impact on C fluxes (either Rs or DOC). We conclude that C accumulation previously attributed solely to N deposition could be partly attributable to their simultaneous acidification.

Recent studies suggest that exposure to air pollution might be associated with severity of sleep-disordered breathing (SDB). However, the association between air pollution exposure, especially particulate matter with aerodynamic diameters <= 2.5 μm (PM₂.₅), and SDB is still unclear. We collected 4312 participants' data from the Taipei Medical University Hospital's Sleep Center and air pollution data from the Taiwan Environmental Protection Administration. Associations of particulate matter with aerodynamic diameters <=10 μm (PM₁₀), PM₂.₅, nitrogen dioxide (NO₂), ozone (O₃) and sulfur dioxide (SO₂) with apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) were investigated by generalized additive models. We found that an interquartile range (IQR) increase in 1-year mean PM₂.₅ (3.4 μg/m³) and NO₂ (2.7 ppb) was associated with a 4.7% and 3.6% increase in AHI, respectively. We also observed the association of an IQR increase in 1-year mean PM₂.₅ with a 2.5% increase in ODI. The similar pattern was found in the association of daily mean PM₂.₅ exposure with increased AHI. Moreover, participants showed significant AHI and ODI responses to air pollution levels in spring and winter. We concluded that exposure to PM₂.₅ was associated with SDB. Effects of air pollution on AHI and ODI were significant in spring and winter.

Mobile in situ concentration and meteorology data were collected for the Chino Dairy Complex in the Los Angeles Basin by AMOG (AutoMObile trace Gas) Surveyor on 25 June 2015 to characterize husbandry emissions in the near and far field in convoy mode with MISTIR (Mobile Infrared Sensor for Tactical Incident Response), a mobile upwards-looking, column remote sensing spectrometer. MISTIR reference flux validated AMOG plume inversions at different information levels including multiple gases, GoogleEarth imagery, and airborne trace gas remote sensing data. Long-term (9-yr.) Infrared Atmospheric Sounding Interferometer satellite data provided spatial and trace gas temporal context.For the Chino dairies, MISTIR-AMOG ammonia (NH₃) agreement was within 5% (15.7 versus 14.9 Gg yr⁻¹, respectively) using all information. Methane (CH₄) emissions were 30 Gg yr⁻¹ for a 45,200 herd size, indicating that Chino emission factors are greater than previously reported.Single dairy inversions were much less successful. AMOG-MISTIR agreement was 57% due to wind heterogeneity from downwind structures in these near-field measurements and emissions unsteadiness. AMOG CH₄, NH₃, and CO₂ emissions were 91, 209, and 8200 Mg yr⁻¹, implying 2480, 1870, and 1720 head using published emission factors. Plumes fingerprinting identified likely sources including manure storage, cowsheds, and a structure with likely natural gas combustion.NH₃ downwind of Chino showed a seasonal variation of a factor of ten, three times larger than literature suggests. Chino husbandry practices and trends in herd size and production were reviewed and unlikely to add seasonality. Higher emission seasonality was proposed as legacy soil emissions, the results of a century of husbandry, supported by airborne remote sensing data showing widespread emissions from neighborhoods that were dairies 15 years prior, and AMOG and MISTIR observations. Seasonal variations provide insights into the implications of global climate change and must be considered when comparing surveys from different seasons.