The determination of values of abundance of antibiotic resistance genes (ARGs) per mass of soil is extremely useful to assess the potential impacts of relevant sources of antibiotic resistance, such as irrigation with treated wastewater or manure application. Culture-independent methods and, in particular, quantitative PCR (qPCR), have been regarded as suitable approaches for such a purpose. However, it is arguable if these methods are sensitive enough to measure ARGs abundance at levels that may represent a risk for environmental and human health. This study aimed at demonstrating the range of values of ARGs quantification that can be expected based on currently used procedures of DNA extraction and qPCR analyses. The demonstration was based on the use of soil samples spiked with known amounts of wastewater antibiotic resistant bacteria (ARB) (Enterococcus faecalis, Escherichia coli, Acinetobacter johnsonii, or Pseudomonas aeruginosa), harbouring known ARGs, and also on the calculation of expected values determined based on qPCR.The limits of quantification (LOQ) of the ARGs (vanA, qnrS, blaTEM, blaOXA, blaIMP, blaVIM) were observed to be approximately 4 log-units per gram of soil dry weight, irrespective of the type of soil tested. These values were close to the theoretical LOQ values calculated based on currently used DNA extraction methods and qPCR procedures. The observed LOQ values can be considered extremely high to perform an accurate assessment of the impacts of ARGs discharges in soils. A key message is that ARGs accumulation will be noticeable only at very high doses. The assessment of the impacts of ARGs discharges in soils, of associated risks of propagation and potential transmission to humans, must take into consideration this type of evidence, and avoid the simplistic assumption that no detection corresponds to risk absence.

Biochars are being increasingly applied in soil for carbon sequestration, fertility improvement, as well as contamination remediation. Phosphoric acid (H3PO4) pretreatment is a method for biochar modification, but the mechanism is not yet fully understood. In this work, biochars and the raw biomass were treated by H3PO4 prior to pyrolysis. Due to an acid catalysis and crosslink, the micropores of the pretreated particles were much more than those without H3PO4 pretreatment, resulting in the dramatical enhancement of specific surface areas of the pretreated particles. Crystalline cellulose (CL) exhibited a greater advantage in the formation of micropores than of amorphous lignin (LG) with H3PO4 modification. The formation mechanisms of micropores were: (a) H+ from H3PO4 contributes to micropores generation via H+ catalysis process; (b) the organic phosphate bridge protected the carbon skeleton from micropore collapse via the crosslinking of phosphate radical. The sorption capacities to carbamazepine (CBZ) and bisphenol A (BPA) increased after H3PO4 modification, which is ascribed to the large hydrophobic surface areas and more abundant micropores. Overall, H3PO4 pretreatment produced biochars with large surface area and high abundance of porous structures. Furthermore, the H3PO4 modified biochars can be applied as high adsorbing material as well as P-rich fertilizer.

To investigate the biological pathways involved in phthalate-induced developmental effects, zebrafish embryos were exposed to different concentrations of di-(2-ethylhexyl) (DEHP) and di-butyl phthalate (DBP) for 96 h. Embryonic exposure to DEHP and DBP induced body length decrease, yolk sac abnormities, and immune responses (up-regulation of immune proteins and genes). The lipidomic results showed that at a concentration of 50 μg/L, DEHP and DBP significantly reduced the levels of fatty acids, triglycerides, diacylglycerol, and cholesterol. These effects are partly explained by biological pathway enrichment based on data from the transcriptional and proteomic profiles. Co-exposure to DBP and ER antagonist did not significantly relieve the toxic symptoms compared with exposure to DBP alone. This indicates that phthalate-induced developmental abnormities in zebrafish might not be mediated by the ER pathway. In conclusion, we identified the possible biological pathways that mediate phthalate-induced developmental effects and found that these effects may not be driven by estrogenic activation.

As a result of human activities, the pollution of metals is becoming ubiquitous in the environment. Among various toxicological mechanisms of action, metals have been considered as endocrine-disrupting chemicals (EDCs) through interference with steroid receptors. However, information regarding the potential endocrine disruption of metals on glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) is especially scarce. In this study, a total of 16 metals were assessed for their GR/MR activities using luciferase reporter gene assay. None of the tested metals exhibited GR or MR agonistic activity, but a total of 7 and 5 candidate metals showed obvious GR and MR antagonistic properties, respectively. All 7 GR antagonistic metals [ BaCl₂, CoCl₂, CuCl₂, Pb(NO₃)₂, LiCl, SnCl₂ and ZnCl₂] inhibited glucocorticoid-responsive gene GILZ expression in J774A.1 cells. Further investigations indicated that the 5 MR antagonistic metals [ CdCl₂, Pb(NO₃)₂, LiCl, MnCl₂ and SnCl₂] antagonized aldosterone-inhibited hepatocellular carcinoma cell proliferation. Among these metals, Pb(NO₃)₂, LiCl, and SnCl₂ showed both anti-glucocorticoid and anti-mineralocorticoid activities. Comprehensive screening and evaluation of GR and MR antagonists and agonists among metals should be considered to better understand the ecological and health risks of metals.

In the 21st century, severe droughts associated with climate change will increase biomass burning (BB) in Brazil caused by the human activities. Recent droughts, especially in 2005, 2010, and 2015, caused strong socioeconomic and environmental impacts. The 2015 drought considered the most severe since 1901, surpassed the 2005 and 2010 events in respect to area and duration. Herein, based on satellite data, the 2005, 2010 and 2015 drought impacts on wildfire episodes and carbon monoxide (CO) variability during the dry and the dry-to-wet transition seasons were examined. The BB occurrences in the dry season were fewer during 2015 than during 2005 (−44%) and 2010 (−47%). Contrasting, the BB events in the dry-to-wet transition season, were higher during 2015 than during 2005 (+192%) and 2010 (+332%). The BB outbreaks were concentrated in the southern and southwestern Amazon during 2005, in the Cerrado region during 2010, and mainly in the central and northern Amazon during 2015, an area normally with few fires. The CO concentration showed positive variations (up to +30%) occurred in the southern Amazon and central Brazil during the 2005 and 2010 dry seasons, and north of 20 °S during the 2015–2016 dry-to-wet transition season. The BB outbreaks and the CO emissions showed a considerable spatiotemporal variability among the droughts of 2005, 2010, and 2016, first of them driven by local conditions in the tropical North Atlantic (TNA), characterized by warm than normal sea surface waters and the other two by the El Niño occurrences.

Electronic cigarette (e-cigarette) use has steadily increased since 2010. Indoor e-cigarette use exposes bystanders to a new source of particulate matter (PM) air pollution. Elevated short-term exposures to PM with a lower measuremented aerodynamic diameter (≤2.5 μm), PM₂.₅ and ultrafine particles (UFPs) have been linked to increased risk of adverse respiratory and cardiac events. This exposure study estimated concentrations of PM₂.₅ and UFPs from indoor e-cigarette use at 0.5 meters (m) and 1 m away from an e-cigarette user and investigated whether these indoor concentrations varied across three common e-cigarette models. One e-cigarette user tested three different e-cigarettes containing the same nicotine solution on three separate occasions and measured concentrations on PM₂.₅ and UFPs at 0.5 and 1 m in a ∼38 m³ office. Continuous measures of PM₂.₅ and UFPs were taken for 5.5 min before e-cigarette use, then the user puffed seven times for 6.5 min (exposure), and for 10 min after ceasing e-cigarette use. Following the initiation of e-cigarette use, levels of PM₂.₅ increased 160-fold at a distance of 0.5 m, and 103-fold at 1 m. The corresponding increases in UFP counts were 5.2, and 3.0-fold higher, respectively. The PM₂.₅ concentrations and UFP counts between e-cigarette models were statistically significantly different at 1 m, but not at 0.5 m. There was substantial variability between distances, e-cigarettes, and replicates. This study indicates that e-cigarette vapors influence PM₂.₅ and UFPs concentrations/counts at close proximity distances indoors; additional research is needed to characterize the composition of those particles and evaluate the impacts of other e-cigarette solutions on indoor air quality.

Maternal transfer toxicity of chemicals has mainly focused in fish on the chemical transfer from maternal generation to offspring, and limited information is available for the evaluation of effects of chemicals from a biological transfer perspective. In this study, first-generation (F0) zebrafish larvae (D. rerio) were exposed to 0, 50, 500 or 5000 ng/L TDCIPP from 14 days post fertilization (dpf) to 120 dpf. F0-generation zebrafish were paired, and F1-generation embryos were collected and continuously exposed to the same concentrations of TDCIPP until 150 dpf. F1-generation females were then paired with unexposed adult males, and maternal transfer effects on survival rate and body length were evaluated. Results demonstrated that maternal exposure to TDCIPP for two generations significantly decreased body length of F2-generation larvae, suggesting the occurrence of maternal transfer toxicity. The transfer of TDCIPP from maternal generation to offspring was evident, but microinjection of equal amounts of TDCIPP did not affect survival and body length of zebrafish larvae. Furthermore, maternal exposure to TDCIPP changed the concentrations of partial mRNAs and proteins in their eggs, and those changes were linked to maternal transfer toxicity (e.g., growth inhibition). These results suggested that in zebrafish changes in biological transfer may explain, at least in part, the observed maternal transfer toxicity of TDCIPP.

We studied arid desert soils from Namibia (Rosh Pinah) that were contaminated with up to 7 mg kg⁻¹ of thallium (Tl) via dust emitted from a local flotation tailing dam. Chemical extractions of waste and soil materials indicated that most of the Tl is strongly bound, in accordance with X-ray diffraction and X-ray absorption spectroscopy data that point to the predominant association of Tl with metal sulfides and phyllosilicates. The isotope fractionation factor ε²⁰⁵Tl of the soil samples (from −0.4 to +3.8) shows a positive linear relationship (R² = 0.62) with 1/Tl, indicative for the mixing of two major Tl pools, presumably anthropogenic Tl and geogenic Tl. The ε²⁰⁵Tl value for the topmost soil samples (∼+3) closely matches the ε²⁰⁵Tl value for post-flotation waste particles with a diameter of <0.05 mm, whereas the bulk flotation waste exhibits a significantly larger ε²⁰⁵Tl value (∼+6). These variations are in accordance with predominant atmospheric transfer of Tl from the tailings to the adjacent soils via fine (dust) particles. The identified minimal Tl alteration in soils indicates that only a small part of the Tl could be potentially released and passively enter the vegetation, local population and/or food chain in the long term. From this viewpoint, Tl does not represent such an important environmental concern as other (abundant) contaminants at the locality. Furthermore, there could be a relevance for other alkaline desert soils, including those where Tl pollution plays a major role.

Fine particulate matter (PM₂.₅) pollution has been a major issue in many countries. Considerable studies have demonstrated that PM₂.₅ pollution is a regional issue, but little research has been done to investigate the regional extent of PM₂.₅ pollution or to define areas in which PM₂.₅ pollutants interact. To allow for a better understanding of the regional nature and spatial patterns of PM₂.₅ pollution, This study proposes a novel framework for delineating regional boundaries of PM₂.₅ pollution. The framework consists of four steps, including cross-correlation analysis, time-series clustering, generation of Voronoi polygons, and polygon smoothing using polynomial approximation with exponential kernel method. Using the framework, the regional PM₂.₅ boundaries for China are produced and the boundaries define areas where the monthly PM₂.₅ time series of any two cities show, on average, more than 50% similarity with each other. These areas demonstrate straightforwardly that PM₂.₅ pollution is not limited to a single city or a single province. We also found that the PM₂.₅ areas in China tend to be larger in cold months, but more fragmented in warm months, suggesting that, in cold months, the interactions between PM₂.₅ concentrations in adjacent cities are stronger than in warmer months. The proposed framework provides a tool to delineate PM₂.₅ boundaries and identify areas where PM₂.₅ pollutants interact. It can help define air pollution management zones and assess impacts related to PM₂.₅ pollution. It can also be used in analyses of other air pollutants.

The study addresses the topic of suitable matrices for chemical analysis in fish monitoring and discusses the effects of data normalization in the context of the European Water Framework Directive (WFD). Differences between species are considered by comparing three frequently monitored species of different trophic levels, i.e., chub (Squalius cephalus, n = 28), (bream, Abramis brama, n = 11), and perch (Perca fluviatilis, n = 19) sampled in the German Danube. The WFD priority substances dioxins, furans and dioxin-like polychlorinated biphenyls (PCDD/F + dl-PCB), polybrominated diphenyl ethers (PBDE), α-hexabromocyclododecane (α-HBCDD), hexachlorobenzene (HCB), mercury (Hg), and perfluorooctane sulfonic acid (PFOS) as well as non-dioxin-like (ndl)-PCB were analyzed separately in fillet and carcass and whole body concentrations were calculated. Hg was analyzed in individual fish fillets and carcasses, all other substances were determined in pool samples, which were compiled on the basis of fish size (3 chub pools, 1 bream pool, 2 perch pools). The data were normalized to 5% lipid weight (or 26% dry mass in the case of Hg and PFOS) for comparison between matrices and species.Hg concentrations were generally higher in fillet than in whole fish (mean whole fish-to-fillet ratio: 0.7) whereas all other substances were mostly higher in whole fish. In the case of lipophilic substances these differences leveled after lipid normalization.Significant correlations (p ≤ .05) were detected between Hg and fish weight and age. Hg concentrations varied least among younger fish. PCDD/F, dl-PCB, ndl-PCB, PBDE, α-HBCDD and HCB correlated significantly (p ≤ .05) with lipid concentrations. Fillet-to-whole fish conversion equations and/or conversion factors were derived for all substances except α-HCBDD. Although more data also for individual fish would be desirable the results are nevertheless a step on the way to translate fillet concentrations of priority substances to whole fish concentrations.