Biodiesel as renewable, environmental friendly, less toxic, and biodegradable is an attractive alternative to fossil fuels and is produced mainly from vegetable oils and animal fats. It is expected, globally, that the use of renewable biofuels, in general, will increase rapidly in the near future. The growing biodiesel production and usage have encouraged assessment of its impact on the environment. The present paper reviews various aspects of biodiesel production using commercial processing technology and biodiesel use through evaluation and analysis of the studies concerning environmental impacts of biodiesel. As a general conclusion, it can be said that biodiesel has the potential to offer a series of perceived benefits such as political, economical, and agricultural, as well as environmental (due to its biodegradability, less toxicity, renewability) and health (greenhouse gas-saving, less harmful exhaust emissions).

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We investigated in this paper the presence of PAHs in human milk from lactating women residing in Lanzhou, a petrochemical industrialized valley city in Northwest China. The PAH concentration levels in human milk samples from 98 healthy women were determined by gas chromatography/mass spectrometry (GC/MS). The associations between the lifestyle factors and the PAHs levels of human milk were analyzed. Moreover, we applied principal component analysis (PCA) method to gain a better insight into the similarities or dissimilarities of the human milk PAH loads and different pathways of source exposure. In addition, the exposure risks of breastfed infants due to PAH ingestion via breast milk were assessed and the relative breast-feeding risk to the total intake dose of infants was addressed. The results showed that the average fat-normalized human milk ∑₁₅PAHs concentrations for the lactating women residing in four districts of Lanzhou, namely, Xigu, Anning, Qilihe, and Chengguan were 320.40, 270.36, 374.04, and 259.84 ng/g of fat, respectively. The ∑₁₅PAHs of human milk from the lactating women of Qilihe District exhibited the highest concentration level, while the concentration level for women from Xigu District is the second highest for the observed human milk ∑₁₅PAHs. And the corresponding BaPeq concentrations for women in Xigu, Anning, Qilihe, and Chengguan districts were 58.29, 47.95, 65.13, and 45.60 ng/g of fat, respectively. A significant correlation was only found between human milk and living district environment (p < 0.05). Although the Spearman correlation analysis showed that there were no significant correlation existing between other lifestyle and human milk PAHs, we confirmed that consuming barbecue food could elevate PAHs levels in human milk: the barbecue intake frequency caused 10% fluctuation of ∑₁₅PAHs concentration between high frequency and low frequency group in our study. Furthermore, the exposure to second-hand smoke can also increase the ∑₁₅PAHs levels in human milk by 4 to 11% here. Ingestion doses of PAHs by infants (19.37–77.75 ng kg⁻¹ day⁻¹) were much higher than the inhalation doses (2.83–16.48 ng kg⁻¹ day⁻¹), which indicated that the ingestion is the main exposure risk pathway for infants. Since there are limited guidelines and standards for PAHs ingestion dose in human milk by infant, we compared the ingestion dose of BaP with the upper bound estimates of BaP dietary exposure of 108 ng kg⁻¹ day⁻¹ for toddlers of ages between 1.5 and 2.5 years of age in the UK reported by Committee on Toxicity of Chemicals in Food (COT) and the data we obtained were lower than this upper bound. However, the estimated margin of exposure (MOE) values of BaP-MOE, PAH2-MOE, PAH4-MOE, and PAH8-MOE were smaller than 10,000 which indicated that there are potential hazard for breastfed infants consuming these human milk samples.

There are few studies about children’s environmental exposure to arsenic (As) in Brazil, most of them being in mining regions. The objective of this study was to contribute to the understanding of biologic concentrations of arsenic in children living in an urban area, in Brazil. A study of arsenic concentrations in capillary blood (n = 270), nail (n = 261), and urine (n = 99) samples, in male and female children, 8 to 10 years old, from two public schools in Rio de Janeiro, was conducted. Socio-economic and health data were obtained through questionnaires. The nail and capillary blood analysis were performed by inductively coupled plasma mass spectrometry (ICP-MS), while urine samples were analyzed using hydride generation atomic absorption spectrometry (HG-AAS). The median, geometric mean, and 95th percentiles of total arsenic concentrations were, respectively, 2.53, 2.40, and 3.58 μg/L in capillary blood; 0.09, 0.10, and 0.24 μg/g in nails; and 12.50, 10.97, and 39.45 μg/L in urine. The geometric mean of urinary arsenic level was above the values reported by international surveys for non-exposed populations. The arsenic concentrations in nails were compatible with the values found in national studies. These outcomes can contribute to the increase of knowledge on biologic concentrations of arsenic in children living in urban areas, in Brazil.

In this study, a novel nanocomposite adsorbent based on magnetic polyaniline and strontium–titanium (MP-SrTiO₃) nanoparticles was synthesized via a simple and low-cost polymerization method for efficiently removing of arsenic(III) ions from aqueous samples. The chemical structure, surface properties, and morphology of the prepared adsorbent were studied using Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM). The main effective parameters on the removal efficiency, such as pH, adsorbent dosage, salt, and contact time, were studied and optimized. The validity of the proposed method was checked by adsorption isotherm and kinetics models. Consequently, the adsorption kinetics corresponded to the first order (R² > 0.99), and the experimental equilibrium fitted the Langmuir model with a maximum monolayer adsorption capacity of 67.11 mg/g (R² > 0.99) for arsenic(III) ions. Corresponding to thermodynamic Vant’s Hof model (ΔG° (kJ/mol), ΔH° (kJ/mol), and ΔS° (kJ/mol K) − 8.19, − 60.61, and − 0.17, respectively), the mechanism and adsorption nature were investigated with that suggested exothermic and physisorption mechanism.

Monitoring of pollution index values in sediments is crucial in assessing the environmental impacts of toxic metals in a given location. These indices are typically acquired using elaborate and tedious calibration curve-dependent techniques such as (inductively coupled plasma – optical emission spectroscopy) ICP-OES and (atomic absorption spectroscopy) AAS. In this study, laser-induced breakdown spectroscopy (LIBS) was used as a simple and fast alternative method for estimating enrichment factor (EF) and contamination factor (CF) of the sediment samples obtained from selected mining sites. Quantitative analyses of three metal targets (Cd, Pb, and Zn) were done using a calibration-free LIBS method based on the Boltzmann population distribution. Both the EF and CF values calculated from classical ICP-OES method provided significantly high correspondence with the respective EF (R² = 0.8862–0.9770, p < 0.01–0.05) and CF (R² = 0.9454–0.9714, p < 0.01) obtained from the developed LIBS method. The intensity-based LIBS approach identified samples AC2 and CCC as the ones with the highest and lowest pollution index values, respectively. The same observation was seen using the concentration-based ICP-OES technique which showed good correlation between the two methods. The correlation results showed the potential of the curve-fitting LIBS analysis in evaluating the level of metal contamination in an area without the preparation of matrix-matched calibration curves.

Hexavalent chromium (Cr(VI)) is a common hazardous contaminant in the environment and carcinogenic or mutagenic to aquatic animals and human beings. Therefore, the removal and detoxification of Cr(VI) have been attracting increasing attention of researchers. Among various conducting polymers, polyaniline (PANI)-based adsorbents have shown an excellent performance on the removal of Cr(VI) because of their redox properties, eased synthesis, and favorable biocompatibility. In this review, the characteristics of various PANI-based adsorbents were described, including PANI-modified nanofiber mats and membranes, PANI/bio-adsorbents, PANI/magnetic adsorbents, PANI/carbon adsorbents, PANI-modified clay composites, and PANI-inorganic hybrid composites. The mechanisms for the detoxification and adsorption of Cr(VI) were also discussed. The results indicated the potential applications of PANI-based adsorbents for the removal of Cr(VI). Graphical abstract ᅟ

A Gram-negative, arsenite-resistant psychrotolerant bacterial strain, Yersinia sp. strain SOM-12D3, was isolated from a biofilm sample collected from a lake at Svalbard in the Arctic area. To our knowledge, this is the first study on the ability of acid-treated and untreated, non-living biomass of strain SOM-12D3 to absorb arsenic. We conducted batch experiments at pH 7, with an initial As(III) concentration of 6.5 ppm, at 30 °C with 80 min of contact time. The Langmuir isotherm model fitted the equilibrium data better than Freundlich, and the sorption kinetics of As(III) biosorption followed the pseudo-second-order rate equation well for both types of non-living biomass. The highest biosorption capacity of the acid-treated biomass obtained by the Langmuir model was 159 mg/g. Further, a high recovery efficiency of 96% for As(III) was achieved using 0.1 M HCl within four cycles, which indicated high adsorption/desorption. Fourier transformed infrared (FTIR) demonstrated the involvement of hydroxyl, amide, and amine groups in As(III) biosorption. Field emission scanning electron microscopy–energy dispersive analysis (FESEM-EDAX) indicated the different morphological changes occurring in the cell after acid treatment and arsenic biosorption. Our results highlight the potential of using acid-treated non-living biomass of the psychrotolerant bacterium, Yersinia sp. Strain SOM-12D3 as a new biosorbent to remove As(III) from contaminated waters.

Recently, a number of studies demonstrated the suitability of hair analysis to assess metal exposure of bats. As many bat species are endangered, such a non-destructive method is particularly suited for this taxon. The present study analyzed the levels of two non-essential (cadmium and lead) and four essential metals (copper, manganese, molybdenum, and zinc) in hairs of three ecologically similar, sympatric bat species, Bechstein’s bat (Myotis bechsteinii), Natterer’s bat (Myotis nattereri), and Brown long-eared bat (Plecotus auritus) from an area in Central Hesse (Germany), as well as metal concentrations in soil samples from the bats’ foraging habitats. Applying a previously established protocol, the analyses were performed using microwave-assisted extraction followed by inductively coupled plasma optical emission spectrometry. Cadmium and lead concentrations in hair did not differ significantly among the three studied species, whereas the following significant differences existed for levels of essential metals in hair. Manganese concentrations in hair were higher in M. bechsteinii and P. auritus than in M. nattereri and Cu concentrations were higher in M. nattereri than in P. auritus. Myotis bechsteinii showed higher Zn concentrations compared to P. auritus and lower Mo concentrations compared to M. nattereri. Reasons for the observed differences among the three studied species could be differential exposure to these metal elements in their foraging areas, related to variation in the species composition of their arthropod diet in combination with different metal levels in the respective prey species, and/or species-specific requirements for essential metals and related variation in physiological regulation of these elements in the bats.

Presently, the discovery of effective drugs and pesticides from eco-friendly biological sources is an important challenge in the field of life sciences. The present research was aimed for standardizing an innovative approach in the evaluation of the biological potentiality of the metabolites of fish-associated bacteria. We have identified 17 skin-associated bacteria from the freshwater fish, giant danio, Devario aquipinnatus. They were screened through biofilm forming and extracellular enzyme producing ability. The results of preliminary antibacterial evaluation of the bacterial supernatants underlined the importance of three potential strains (BH8, BH10 and BH11) for further applied research. Hence, such strains were subsequently subjected to a novel extraction procedure to overcome the difficulties found in polar solvents mixed with the supernatant. The lyophilized cell-free supernatant (LCFS) of 3 isolates were individually extracted by using methanol. During the testing of LCFS’s methanolic extract (LCFS-ME) of 3 isolates, only the extract of BH11-strain exhibited potent inhibitory activity against the pathogenic bacteria and fungi. Furthermore, the larvicidal and mosquitocidal assays on the filariasis vector, Culex quinquefasciatus also showed its potent toxicity on both the adults and developmental instars of mosquito. Through molecular and phylogenetic analyses, the BH11 strain was identified as Salmonella bongori (KR350635). The present finding emphasized that the S. bongori could be an important novel source of effective antimicrobials and mosquitocidal agents.