2,4,6-Trinitrotoluene (TNT) is a nitroaromatic explosive, highly toxic and mutagenic for organisms. In this study, we report for the first time the screening and isolation of TNT-degrading bacteria from Antarctic environmental samples with potential use as bioremediation agents. Ten TNT-degrading bacterial strains were isolated from Deception Island. Among them, Pseudomonas sp. TNT3 was selected as the best candidate since it showed the highest tolerance, growth, and TNT biotransformation capabilities. Our results showed that TNT biotransformation involves the reduction of the nitro groups. Additionally, Pseudomonas sp. TNT3 was capable of transforming 100 mg/L TNT within 48 h at 28 °C, showing higher biotransformation capability than Pseudomonas putida KT2440, a known TNT-degrading bacterium. Functional annotation of Pseudomonas sp. TNT3 genome revealed a versatile set of molecular functions involved in xenobiotic degradation pathways. Two putative xenobiotic reductases (XenA_TNT3 and XenB_TNT3) were identified by means of homology searches and phylogenetic relationships. These enzymes were also characterized at molecular level using homology modelling and molecular dynamics simulations. Both enzymes share different levels of sequence similarity with other previously described TNT-degrading enzymes and with their closest potential homologues in databases.

Natural sources, such as soil and wind-erosion dust (SWD), biomass open burning (BOB), sea salt spray (SSAS) and biogenic source (BIO), are major contributors to atmospheric emissions of trace elements (TEs) globally. In this study, we used a comprehensive approach to account for area-, production- and biofuel consumption-based emission factor calculation methods, and thus developed an integrated high-resolution emission inventory for 15 types of TEs (As, B, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, V and Zn) originated from natural sources in China for the year 2015. The results show that national emissions of TEs in 2015 range from 7.45 tons (Hg) to 1, 400 tons (Zn) except for the extremely high emissions of Mn (10, 677 tons). SWD and BIO are identified as the top two source contributors, accounting for approximately 67.7% and 26.1% of the total emissions, respectively. Absolute emissions of TEs from natural sources are high in the Xinjiang, Inner Mongolia and Tibet autonomous regions with large areas of bare soil and desert. However, emission intensity of TEs per unit area in the Southern provinces of China is higher than those in Northern China and Southwestern China, with the Yunnan and Sichuan provinces displaying the highest emission intensity. Our results suggest that controlling SWD can play a significant role in reducing fugitive particulate matter and the associated emissions of TEs from natural sources in China; and desertification control is particularly critical in the Northwest provinces where the majority of deserts are located.

Straw amendment and plant root exudates modify the quality and quantities of soil dissolved organic matter (DOM) and then manipulate the fractions of soil selenium (Se) and its bioavailability. Two typical soils with distinct pH were selected to investigate the effect of different contributors on DOM-Se in soil. The mechanisms relying on the variation in DOM characteristics (quality, quantity and composition) were explored by UV–Vis, ATR-FTIR and 3D-EEM. Straw amendment significantly (p < 0.05) suppressed the selenate bioavailability. The reduction in wheat Se content was greater in krasnozems than in Lou soil, as more HA fraction appeared in krasnozems. The root exudates of wheat mainly elevated the low molecular hydrophilic compounds (Hy) in soil, which contributed to the SOL-Hy-Se fractions and thus grain Se in soils (p < 0.01). However, straw amendment promoted DOM transforming from small molecules (Hy and FA) to aromatic large molecules (HA), when accompanied with the reduction and retention of Se associated with these molecules. As a result, selenium bioavailability and toxicity reduced with DOM amendment and DOM-Se transformation.

Microplastics (MPs) are currently one of the primary marine pollution problems around the world. MPs are distributed throughout the water column, dependent mainly on the density that is given by the polymer type, as well as the location, depth, and velocities of the water flows. This situation allows all aquatic organisms to be exposed to MPs. Furthermore, toxic substances can adhere to the MPs, making the consumption of fish with MPs a risk to human health. The aim of this study was to evaluate and characterize the microplastics present in the gastrointestinal tract of six species of fish which had the highest human consumption in Campeche, Mexico and their relationship with the density of MPs founded. A total of 316 microplastic particles from 240 individuals were found with 1.31 ± 2.59 of microplastics per fish. The results indicate that there are differences (KW–H = 53.14) between the densities of the MPs present in demersal fish (1.41 ± 0.4 g cm⁻³) with respect to the pelagic species (1.04 ± 0.24 g cm⁻³). Likewise, differences were found between fibers, fragments, and pellets present in the studied fish with a pelagic: demersal ratio of 1: 2.4 for all microplastics. The demersal species Haemulon plumierii (n = 40) presented the highest number of MPs with 115 items in total, 73 fibers, and 42 fragments. The results of this research show the first evidence that the density of the material from which microplastics are made play a key role determining their fate in marine fish habitats.

Black-spotted frogs and bullfrogs from an e-waste polluted area were collected and examined for legacy and emerging organophosphorus flame retardants (PFRs) and plasticizers. Total concentrations of PFRs and plasticizers were 0.62–15 ng/g wet weight (ww) and 316–4904 ng/g ww in muscles, 2.2–59 ng/g ww and 127–5757 ng/g ww in eggs and gonads, and 1.2–15 ng/g ww and 51–1510 ng/g ww in oviducts, respectively. For muscle tissues, concentrations of ∑PFRs, triethyl phosphate, tris-(2-chloroethyl) phosphate, and tris-(chloro-2-propyl) phosphate were significantly higher in the males than females (p < 0.05). However, for reproductive tissues, eggs exhibited higher levels of those contaminants than gonads (p < 0.05). No significant sex difference in levels of plasticizers was observed in muscles. In contrast, levels for (2-ethylhexyl) phthalate, di-n-butyl phthalate, and di-iso-butyl phthalate in gonads were significantly higher than those in eggs (p < 0.05). Significantly negative linear correlations between maternal transfer ratios and log KOW were found in female frogs. Paternal transfer potentials were first significantly and positively correlated to log KOW (<6) and then decreased afterward in the males. These results indicated that parental transfer was answer for the sex-specific accumulation of PFRs and plasticizers in frogs.

In this study, a novel rotating anode-based reactor (RAR) was designed to investigate its effectiveness in removing dissolved salts (i.e., Br⁻, Cl⁻, TDS, and SO₄²⁻) from saline water samples. Two configurations of an impeller’s rotating anode with various operation factors, such as operating time (min), rotating speed (rpm), current density (mA/cm²), temperature (°C), pH, and inter-electrode space (cm), were used in the desalination process. The total cost consumed was calculated on the basis of the energy consumption and aluminum (Al) used in the desalination. In this respect, operating costs were calculated using optimal operating conditions. Salinity was removed electrochemically from saline water through electrocoagulation (EC). Results showed that the optimal adjustments for treating saline water were carried out at the following conditions: 150 and 75 rpm rotating speeds for the impeller’s rod anode and plate anode designs, respectively; 2 mA/cm² current density (I), 1 cm² inter-electrode space, 25 °C temperature, 10 min operation time, and pH 8. The results indicated that EC technology with impeller plates of rotating anode can be considered a very cost-effective technique for treating saline water.

Infections caused by carbapenem-resistant Enterobacteriaceae are a growing concern worldwide. Raoultella ornithinolytica is a species in the Enterobacteriaceae family which can cause hospital-acquired infections and is sporadically reported as carbapenem-resistant from human and environmental sources. In this study, we firstly report on an NDM-1-producing R. ornithinolytica, Rao166, isolated from drinking water in an animal cultivation area in China. In addition to carbapenem-resistance, Rao166 was resistant to several other antibiotics including gentamicin, sulfamethoxazole-trimethoprim, tetracycline and fosfomycin. Rao166 carried a novel IncFIC-type megaplasmid, 382,325 bp in length (pRAO166a). A multidrug resistance region, 60,600 bp in length, was identified in the plasmid containing an aac(3)-IId-like gene, aac(6′)-Ib-cr, blaDHA₋₁, blaTEM₋₁B, blaCTX₋M₋₃, blaOXA₋₁, blaNDM₋₁, qnrB4, catB3, arr-3, sul1, and tet(D). Results from virulence assays implied that Rao166 has considerable pathogenic potential. Although pRAO166a was found to be non-transmissible, dissemination of the NDM-1 producing strain may occur from well water to humans or animals through cross-contamination during food preparation or directly via drinking water, and potentially lead to difficult-to-treat infections. Thus, contamination of well water by this carbapenem-resistant and presumptively virulent strain of R. ornithinolytica should be considered a potential public health risk.

Arsenic, a class I human carcinogen, is ubiquitously found throughout the environment and around the globe, posing a great public health concern. Notably, Bangladesh and regions of West Bengal have been found to have high levels (0.5–4600 μg/L) of arsenic drinking water contamination, and approximately 50 million of the world’s 200 million people chronically exposed to arsenic in Bangladesh alone. This study was carried out to examine genome-wide gene expression changes in individuals chronically exposed to arsenic-contaminated drinking water. Our study population includes twenty-nine Bangladeshi female participants with urinary arsenic levels ranging from 22.32 to 1828.12 μg/g creatinine. RNA extracted from peripheral blood mononuclear cells (PBMCs) were evaluated using RNA-Sequencing analysis. Our results indicate that a total of 1,054 genes were significantly associated with increasing urinary arsenic levels (FDR p < 0.05), which include 418 down-regulated and 636 up-regulated genes. Further Ingenuity Pathway Analysis revealed potential target genes (DAPK1, EGR2, APP), microRNAs (miR-155, -338, −210) and pathways (NOTCH signaling pathway) related to arsenic carcinogenesis. The selection of female-only participants provides a homogenous study population since arsenic has significant sex dependent effects, and the wide exposure range provides new insight for key gene expression changes that correlate with increasing urinary arsenic levels.