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Rhizodegradation performed by plant roots and the associated bacteria is one of the major mechanisms that contribute to removal of petroleum hydrocarbons (PHCs) during phytoremediation. In this study, the pot-culture experiment using wild ornamental Hylotelephium spectabile (Boreau) H. Ohba was designed to explore responses and roles of roots, microbes, and degrading genes in the rhizodegradation process. Results showed that PHCs degradation rate by phytoremediation was up to 37.6–53.3% while phytoaccumulation accounted for a low proportion, just at 0.3–13.3%. A total of 37 phyla were classified through the high throughput sequencing, among which Proteobacteria, Actinobacteria, and Acidobacteria were the three most dominant phyla, accounting for >60% of the phylum frequency. The selective enrichment of PHC degraders with high salt-tolerance, including Alcanivorax and Bacteroidetes, was induced. Generally, relative abundance of the PHC degrading genes increased significantly with an increase in PHCs concentrations, and the gene copy number in the phytoremediation group was 1.46–14.44 times as much as that in the unplanted controls. Overall, the presence of PHCs and plant roots showed a stimulating effect on the development of specific degraders containing PHC degrading genes, and correspondingly, a biodegradation-beneficial community structure had been constructed to contribute to PHCs degradation in the rhizosphere.

The interactions between nanoparticles and humic acid (HA) are critical to understanding the environmental risks and applications of nanoparticles. However, the interactions between HA fractions and graphene oxide (GO, a popular carbon nanosheet) at the molecular level remain largely unclear. Four HA fractions with molecular weights ranging from 4.6 to 23.8 kDa were separated, and the large HA fractions presented low oxygen contents and many aromatic structures. The binding constants of the large HA fractions on GO were 2.6- to 3551-fold higher than those of the small HA fractions, while the maximum adsorption capacities of the larger HA fractions onto GO were much higher. Atomic force microscopy (AFM) found that the small and large HA fractions were spread over the center and the edge of the GO nanosheets, respectively. Density functional theory (DFT) simulation and nuclear magnetic resonance spectroscopy confirmed the above phenomena (three adsorption patterns, "vs", "ps", and "pea") and revealed that HA bonded to the GO nanosheets mainly through van der Waals force and π-π interactions. The integrating analysis of binding affinity, AFM, and DFT provides new insights into the environmental behavior of GO and the applications of GO in pollutant removal under exposure from HA.

The development of effective and affordable electrocatalysts for the oxygen reduction reaction (ORR) is critical for the renewable-energy technologies. Here, we present a new manganese iron oxide (MnFeO

Canola (Brassica napus) is one of the most economically important oilseed crops in Canada. Fusarium seedling blight is a root disease with the potential to cause severe yield reductions in canola. Fusarium spp. are commonly isolated root pathogens from fields in Alberta. Fusarium infection can also cause root rot in adult plants. In this study, 128 isolates identified as Fusarium spp. were recovered from field soils in central Alberta and from the roots of diseased canola plants with typical Fusarium seedling blight symptoms. Six species of Fusarium were identified, with Fusarium acuminatum as the predominant species (57 of 128 isolates, 44.5%). Phylogenetic analyses based on the translation elongation factor 1-α and the internal transcribed spacer sequence data were used for evaluation of genetic variations, and also used for Fusarium spp. identification in combination with morphological characteristics and polymerase chain reaction-based analyses. Based on disease ratings in pathogenicity tests, six isolates of F. avenaceum showed high aggressiveness on canola. Also, the aggressiveness varied within all Fusarium spp. No correlation was observed between aggressiveness and the geographic origin of the isolates.

Oil spills occur frequently worldwide, resulting in severe damage to water and to human health. Polycyclic aromatic hydrocarbons (PAHs) are the primary toxic components in oil contamination. PAH-degrading microbes have attracted significant attention, but difficulty in their selection and proliferation limits their applications. Graphene oxide quantum dots (GOQDs) improve the proliferation of an indigenous PAH-degrading strain, Bacillus cereus, more effectively than large graphene oxide flakes. Bacillus cereus can metabolize a variety of xenobiotic aromatic compounds as carbon sources and is used in bioremediation. GOQDs contain a variety of aromatic hydrocarbon structures, explaining why the bacteria achieve strong tolerance to PAHs. GOQD-activated cytokinesis increases the secretion of substances important for biofilm formation (extracellular polymeric substances), which further accelerates PAH removal. Proteomic analysis reveals the molecular mechanisms underlying GOQD-induced microbial proliferation. GOQDs induce the overexpression of microbial divisomal proteins associated with division initiation, DNA replication and peptidoglycan hydrolysis/synthesis. Importantly, PAH removal mediated by GOQD-treated Bacillus cereus does not require the addition of GOQDs. The effects of GOQDs on a strain persist for at least 20 generations, suggesting their possible use in low-cost applications. This work proposes a strategy to remove oil contamination using an indigenous bacterial system enhanced by nanomaterials.

Decorative ornamental plants have been applied as hyperaccumulators/phytoremediators to a wide spectrum of heavy metal contaminants. In this study, pot culture experiments were conducted to investigate the Sn tolerance and accumulation in Impatiens balsamina L., Mirabilis jalapa L. and Tagetes erecta L., in order to assess the possibility of these three ornamental plants to be used as phytoremediators of Sn-contaminated soil. Results show that all three plants exhibited strong tolerance to Sn contamination, and no significant visual toxicity was observed for all three plants grown under most of the Sn treatments. The amount of Sn accumulated in the three plants was positively correlated with the Sn concentration in the soil. The order of the Sn accumulative capacity was Impatiens balsamina &gt, Mirabilis jalapa &gt, Tagetes erecta. Impatiens balsamina and Tagetes erecta showed a low translocation ability (TF) (&lt, 1), and the roots accumulated the highest Sn concentration, but Impatiens balsamina showed a relatively high bioconcentration factor (BCF, Sn concentration in each part &gt, 100 mg/kg after Sn treatment of 500 mg/kg). Meanwhile, the TF of Mirabilis jalapa was &gt, 1, and the fluorescence accumulated the most Sn. In combination with the adaptation to high concentrations of various heavy metals, these three ornamental plants are potential candidates for Sn mining tailings or contaminated soil.

With the wide use of graphene-like nanosheets, especially in agriculture, their release into the environment, it is crucial to grasp the fate of nanosheets in soil and minimum ecological risks. The present work discovered that leaching and migration of nanosheets (rGO) in soil is affected by soil porosity and adsorption processes. And the contents of rGO−Pd in soil layers and leachate increased and then decreased with the decreased of soil porosity. Moreover, physicochemical properties of rGO−Pd nanosheets changed by leaching processes, especially the changes of morphology, thickness and oxygen functional groups. Leaching of rGO−Pd also interfered the soil microbial homeostasis accompanied by the increase of microbial species richness and community diversity. In addition, rGO−Pd altered the usage of carbon sources by edaphon. The utilization of carbon sources by soil microbes, such as polymers, sugars, phenolic acids, carboxylic acids, amino acids, and amines, was also reduced by nanosheets. These findings provide new insights into environmental behaviors of nanomaterials and nanogeochemistry.

In this work, nitrogen doped g-C3N4 (NCN) with the extremely narrow band gap was prepared and applied for the photodegradation of phenols. Experiments and DFT (the density functional theory) computation identified that N-doping introduced in the g-C3N4 matrix by substituting C atoms. DFT, PL (photoluminescence) spectra, optical property characteristic and PEC (photoelectrochemical) indicated that NCN possess extremely narrow band gap, efficient photogenerated carrier separation and the charge transfer, which enhanced the absorption of visible light and further promoted the photocatalytic activity. As a result, NCN(2:2) showed about twice higher photodegradation efficiencies and 3 times rate constant than pristine g-C3N4. The radical trapping experiments showed that •O2- radical and h+ served as crucial active species during the whole photodegradation reaction. This work can provide a strategy to enhance the photocatalytic activity of photocatalysts via introduce foreign atoms in matrix.

In the past two decades, more and more attentions have been paid to soil-derived greenhouse gases (GHGs) including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) because there are signs that they have rising negative impacts on the sustainability of the earth surface system. Farmlands, particularly paddy soils, have been regarded as the most important emitter of GHGs (nearly 17%) due to a large influx of fertilization and the abundance in animals, plants and microorganisms. Geobacter, as an electroactive microorganism widely occurred in soil, has been well studied on electron transport mechanisms and the direct interspecies electron transfer. These studies on Geobacter illustrate that it has the ability to be involved in the pathways of soil GHG emissions through redox reactions under anaerobic conditions. In this review, production mechanisms of soil-derived GHGs and the amount of these GHGs produced had been first summarized. The cycling process of CH4 and N2O was described from the view of microorganisms and discussed the co-culture relationships between Geobacter and other microorganisms. Furthermore, the role of Geobacter in the production of soil-derived GHGs is defined by biogeochemical cycling. The complete view on the effect of Geobacter on the emission of soil-derived GHGs has been shed light on, and appeals further investigation.

Ag/g-C3N4 composite photocatalyst, which was synthesized by thermal polymerization of melamine precursor combined with the photo-assisted reduction method, was applied as an efficient visible-light-driven photocatalyst for inactivating Escherichia coli (E. coli). The composite photocatalysts exhibited significantly enhanced photocatalytic disinfection efficiency than pure g-C3N4 powders. The mechanism of enhanced disinfection activity was systematically investigated by UV–visible diffuse reflectance spectra, photoluminescence spectra, and photo-electrochemical methods including photogenerated current densities, electrochemical impedance spectroscopy (EIS) spectra and Mott–Schottky plots. The enhanced photocatalytic bactericidal effect was attributed to the hybrid effect from Ag and g-C3N4, which resulted in enhanced adsorption of visible light, reduced recombination of free charges, rapid separation and transportation of photogenerated electrons–holes. The disinfection mechanism was studied by employing chemical scavengers and ESR technology, indicating the important role of h+ and e−. Considering the bulk availability and excellent disinfection activity of Ag/g-C3N4, it is a promising solar-driven photocatalyst for cleaning microbial contaminated water in practice.

Given the research and applications of carbon nanomaterials (CNMs) in various fields, the safety of CNMs has attracted significant attention. As with any pollutant, the separation and analysis of CNMs in complex environmental and biological matrices are the prerequisites for the precise evaluation of nanosafety. However, compared with conventional pollutants and other nanomaterials, the methodology of separation and analysis of CNMs in complex matrix remains immature. To clarify the targeted CNMs for analysis, this review explored the transformation and degradation of CNMs in natural environments and organisms. The sample treatments, for example, extraction, separation and enrichment of CNMs, are then discussed. Subsequently, the available analytical approaches including microscopic, scattering, diffraction, spectroscopic and other techniques are illustrated and compared. Herein, the combined employment of diverse techniques is highlighted to minimize the individual limitations. Finally, the challenges and perspectives for the quantitative/qualitative determination of CNMs in environmental and biological matrices are proposed.

Degradation efficiency, product distribution and reaction pathway of N-nitrosodimethylamine (NDMA) photocatalytic degradation over TiO 2 nanotube(TiNT), Au-modified TiO 2 nanotube(Au/TiNT) and TiO 2 nanopowder(TiO 2 ) were investigated to evaluate the tube effect. The results show that TiO 2 nanotube was prepared and tubular morphology was kept after Au modification. The degradation efficiencies of NDMA over TiNT and Au/TiNT are significantly higher than that over TiO 2 powder, DMA becomes to be the major product, and NO 2 − production is also detectable, which all stem from the tubular morphology of TiNT and Au/TiNT. In the presence of TiNT and Au/TiNT, the small NDMA molecules enter into the nanotube and lead to a higher concentration and a closer contact in a nanotube structure space, resulting in remarkable high degradation efficiencies of NDMA, and also initiating new photocatalytic reaction pathway derived from effectively contacts between radical intermediate and NO 2 − products in the nanotube structure. The nanotubular morphology of TiNT and Au/TiNT plays an important role in enhancing NDMA photocatalytic performances.

Nanomaterials develop rapidly and are applied in various fields. Generally, these nanomaterials are released into the environment and lead to potential nanotoxicity and environmental risks. Importantly, the environmental behaviors and properties of nanomaterials will inevitably be influenced by environmental factors. As a result, biological responses of the nanomaterials under the action of environmental factors are largely different from those of pristine nanomaterials. Therefore, this review discussed the influence of environmental factors (e.g., light irradiation, natural organic matter, ionic strength, coexisting contaminants, temperature, biomedium and chemical surface modifications) on nanotoxicity and the relevant knowledge gaps, and then explored the mechanisms thereof. Environmental factors affected nanotoxicity by regulating their physicochemical features, changing physiological damage, oxidative stress, and biomolecular responses caused by nanomaterials. In addition, the synergic effects of environmental factors and the dominant factors in natural environment should be taken into consideration when nanotoxicity is discussed. At the end of the review, the global perspectives of nanotoxicity with the influence of environmental factors are proposed.

From eastern to western areas, per- and polyfluoroalkyl substances (PFASs) were detected at substantial levels in the outdoor dust across mainland China. Urban samples generally showed higher levels compared with those of rural samples. Compared with neutral PFASs, ionizable PFASs (C4-C12 perfluoroalkyl carboxylic acids and C4/C8 perfluoroalkyl sulfonic acids) were more abundant, with the highest total concentration up to 1.6 × 10(2) ng/g and perfluorooctanoic acid (PFOA) being a predominant analogue. Fluorotelomer alcohols (FTOHs) and polyfluoroalkyl phosphoric acid diesters (DiPAPs) were both detected in most samples with total concentrations of 0.12-32 and 0.030-20 ng/g, respectively. Perfluorooctane sulfonamidoethanols/sulfonamides (FOSE/As) were detected at low frequencies (

Despite the frequent detection of benzotriazoles (BTRs) and benzothiazoles (BTHs) in groundwater and surface-water environments, knowledge on their occurrence and profile in tap water is still scarce. This study demonstrates widespread occurrence of these compounds in tap water from 51 major cities in China, which have ranges of

To study the uptake pathways of 3 main hexabromocyclododecane diastereoisomers (α-, β-, and γ-HBCDs) in wheat, four closed chambers were designed to expose wheat to HBCDs via air and/or soil for 4 weeks. The results showed that HBCDs could be absorbed by wheat both via root from soil and via leaf from air. The Rt values (ratio of HBCDs from root-to-leaf translocation to the total accumulation in leaves) ranging from 14.4 to 29.8% suggested that acropetal translocation within wheat was limited. A negative linear relationship was found between log Rt and log Kow of the HBCD diastereoisomers (p0.05). The bioconcentration factors (BCFs, (μg/g wheat tissues)/(μg/g soil)) were in the order α-β-γ-HBCD in wheat roots and stems, being negatively related to their Kow values. No such correlation was found in leaves, where the HBCDs came mainly from air distribution. The results of enantiomeric fractions indicated that the (-)-enantiomer of α- and γ-HBCDs and the (+)-β-enantiomer were selectively accumulated. Furthermore, β- and γ-HBCDs were transformed to α-HBCD in the wheat, with 0.309-4.80% and 0.920-8.40% bioisomerization efficiencies at the end of the experiment, respectively, being the highest in leaves. Additionally, no isomerization product from α-HBCD was found.

Pot experiments were conducted to evaluate the phytoremediation of B[a]P contaminated soil using two ornamental plants (Tagetes patula and Mirabilis jalapa). The results showed that the dry biomass of two plants was increased at low B[a]P contaminated soil and then inhibited with increasing B[a]P concentrations. It exhibited a significantly positive linear relationship between B[a]P absorption in roots, stems, leaves and shoots of the tested plants and the concentration of B[a]P in soils (P

Nanoparticles (NPs) with excellent properties have been rapidly developed and applied in various fields such as phototherapy, early cancer diagnosis, drug carriers, electronic components, cosmetics, food additives, water treatment, and soil remediation. Humans could be directly exposed to these NPs via these applications. These NPs or NP-containing products could also be released into the environment, leading to potential environmental risks. Therefore, the environmental and health risks of nanomaterials urgently need to be assessed, especially for the development of control methodologies. Methods for control or regulation of nanomaterial risks are still in the developmental stages, and some knowledge gaps and ambiguities still exist. To address these knowledge gaps and to guarantee the sustainable development of nanote- chnology, this review discusses the attenuation of nanotoxicity and mechanisms thereof. Physicochemical properties of NPs, such as size, purity, and surface properties (surface charge, hydrophilicity, and surface modification) influence their interactions with biological systems. Environmental conditions during the interaction of NPs with cells, such as exposure dose and time and reaction media, also affect nanotoxicity. Optimization of these physicochemical properties and environmental conditions is expected to aid the design of ideal NPs and control adverse effects of NPs. Nanotoxicity has been reported to be reduced by adjusting size, purity, surface properties (surface charge, hydrophilicity, and surface modification), exposure dose and time, and reaction media of NPs. Herein, the corresponding progress and challenges are also discussed individually. Moreover, this review elaborates on toxic mechanisms and attenuation of nanotoxicity involving five aspects: chemophysiological damage of cellular and subcellular structures, oxidative stress, genes, proteins, and metabolism. Understanding mechanisms underlying the interaction of NPs with biological systems would be conducive to the prediction of nanotoxicity and the design of experiments to attenuate this nanotoxicity. Currently, further studies need be conducted to explore NP uptake, absorption, distribution, interaction, and elimination in biological systems or cells. Globally, the methods of nanotoxicity attenuation remain immature, and well-corroborated methods are unavailable. Finally, perspectives on future research in nanotoxicity attenuation are proposed. An understanding of nanotoxicology and the development of related control methods affect multiple disciplines, including medicine, chemistry, physics, biology, and environmental science. Therefore, multidisciplinary experts need to urgently work together to ensure the sustainable development of nanotechnology.

Bioelectrochemical system is an emerging technology for the remediation of soils contaminated by petroleum hydrocarbons. However, performance of such systems can be limited by the inefficient mass transport in soil. Here we report a new method of sand amendment, which significantly increases both oxygen and proton transports, resulting to increased soil porosity (from 44.5% to 51.3%), decreased Ohmic resistance (by 46%), and increased charge output (from 2.5 to 3.5Cg(-1)soil). The degradation rates of petroleum hydrocarbons increased by up to 268% in 135d. The degradation of n-alkanes and polycyclic aromatic hydrocarbons with high molecular weight was accelerated, and denaturing gradient gel electrophoresis showed that the microbial community close to the air-cathode was substantially stimulated by the induced current, especially the hydrocarbon degrading bacteria Alcanivorax. The bioelectrochemical stimulation imposed a selective pressure on the microbial community of anodes, including that far from the cathode. These results suggested that sand amendment can be an effective approach for soil conditioning that will enhances the bioelectrochemical removal of hydrocarbons in contaminated soils.

Several iron and cobalt dual metal- and nitrogen-doped carbons (FeCoNCs) are synthetized by using a typical metal–organic framework, ZIF-67, as the precursor for oxygen reduction reaction. With the rise of pyrolysis temperature (700 °C–1000 °C), the morphological evolution and structural changes of resultant FeCoNC samples and the subsequent differences in oxygen reduction performances were also explored. The maximum power density of the FeCoNC-modified air-cathode microbial fuel cell (MFC) reaches 1769.95 mW m−2, which is superior to that of Pt/C-modified MFC (1410.31 mW m−2). A N2 adsorption–desorption experiment reveals the presence of abundant mesoporous in the structure of the as-prepared FeCoNC material pyrolized at 900 °C (FeCoNC-900), and the Brunauer–Emmett–Teller model discloses its high specific surface area. Rotating disk electrode test results demonstrate a four-electron transfer pathway for the FeCoNC-900 catalyst. Furthermore, the MFC device modified by the as-prepared FeCoNC materials shows excellent durability and stability as cathode oxygen reduction catalyst.

In this study, a series of NCN/BiWO (NCN = N-doped graphitic carbon nitride, BiWO = Bi2WO6) were fabricated successfully, which were characterized by XRD, TEM, FTIR, BET, UV–vis spectrometry, XPS and PL. Under visible light irradiation, the optimum mass ratio of 60 % NCN/BiWO could reach 93.1 % removal efficiency of phenol within 5 h, which was about 6.9 times as that pure Bi2WO6. And the degradation rate constant of 60 % NCN/BiWO (2.6726 min-1) was about 18.5 times as that of pure Bi2WO6 (0.1442 min-1). According to the result of UV–vis absorption spectra, VB-XPS spectra and photoelectrochemistry performance, the photocatalytic mechanism of 60 % NCN/BiWO was revealed, indicating that the narrow band gap of 60 % NCN/BiWO is the main factor on the high photocatalytic activity. The stable and recyclable properties also were done, showing highly suitable for practical application.

Graphene oxide (GO), a novel two-dimension carbon nanomaterial, has showed tremendous potential for utilization in intelligent manufacturing and environmental protection. In parallel, tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is widely distributed in the water environment and represents a great threat to ecosystem health. However, the related knowledge remained absent regarding the impact of GO on the biological risks of TDCIPP. Herein, GO significantly reduced the mortality and malformation rates of zebrafish induced by TDCIPP maximumly by 28.6% and 41.8%, respectively. Decreased mitochondrial respiratory chain (MRC) enzyme and ATP activity induced by TDCIPP were mitigated by GO. Integrating proteomics and metabolomics revealed TDCIPP obviously induced the downregulation of the proteins and metabolites involved in the cytoskeleton, mitochondrial function, carbohydrate and amino acid metabolism, and the TCA cycle, but the alterations were attenuated by GO. GO primarily promoted MRC activity, carbohydrate metabolism, and fatty acid β-oxidation, thus activating the energy metabolism of zebrafish and leading to antagonistic effects on the developmental toxicity of TDCIPP. These results provide a novel view on the co-exposure of GO with other pollutants and promote the reconsideration of the environmental risks of GO.

Bioelectrochemical systems (BESs) are widely investigated as a promising technology to recover bioenergy or synthesize value-added products from wastewaters. The performance of BES depends on the activity of electroactive biofilm (EAB). As the core of BES, it is still unclear how the EAB is formed from mixed inoculum, and how exoelectrogens compete with non-exoelectrogens. Here we confirmed that microbial community composition and the morphology of EAB on the electrode including the thickness and porosity of the biofilm are critical for the performance of BES, and these properties can be simply controlled by the substrate concentration during EAB formation. The EAB formed with 0.1 g/L of acetate (EAB-0.1) exhibited a 90% higher current density than that formed with 1.0 g/L acetate (EAB-1.0). EAB-0.1 had a 50% higher electroactivity per biomass and a 20% thinner thickness than EAB-1.0, which was partly due to the 54% decrease of insulative polysaccharide in biofilm. Limited acetate also imposed a selective pressure to enrich Geobacter up to 88% compared to 72% when acetate was abundant. Our findings demonstrate that a highly active EAB can be formed by limiting substrate concentration, providing a broader understanding of the EAB formation process, the ecology of interspecies competitions and potential applications for bioenergy recovery and trace toxicant detection in the future.

Formaldehyde poses significant threats to the ecosystem and is widely used as a toxicity indicator to obtain electrical signal feedback in electroactive biofilm (EAB)-based sensors. Although many optimizations have been adopted to improve the performance of EAB to formaldehyde, nearly no studies have discussed the toxicity of formaldehyde to EAB. Here, EABs were acclimated with a stable current density (8.9 ± 0.2 A/m2) and then injected with formaldehyde. The current density decreased by 27% and 98% after the injection of 1 and 10 ppm formaldehyde, respectively, compared with that in the control. The ecotoxicity of formaldehyde caused the irreversible loss of current with 3% (1 ppm) and 81% (10 ppm). Confocal laser scanning microscopy and scanning electron microscopy results showed that the redox activity was inhibited by formaldehyde, and the number of dead/broken cells increased from 2% to 40% (1 ppm) and 91% (10 ppm). The contents of the total protein and extracellular polymer substances decreased by more than 28% (1 ppm) and 75% (10 ppm) because of the cleavage reaction caused by formaldehyde. Bacterial community analysis showed that the proportion of Geobacter decreased from 81% to 53% (1 ppm) and 24% (10 ppm). As a result, the current production was significantly impaired, and the irreversible loss increased. Toxicological analysis demonstrated that formaldehyde disturbed the physiological indices of cells, thereby inducing apoptosis. These findings fill the gap of ecotoxicology of toxicants to EAB in a bioelectrochemical system.

The environmental release of graphene oxide (GO) will certainly induce the GO exposure to plants. To date, the influence of GO on the intracellular structures and the endophytic bacterial ecology of plants have been rarely reported. In the present study, the rice seedlings were exposed to GO (5 mg/L) under hydroponic condition for fifteen days with periodic stir. The cellular structures damage, GO deposition and oxidative stress were found in rice root after GO exposure. A Illumina analysis based on the bacterial 16 S rRNA gene showed that the richness, evenness and diversity of endophytic bacterial communities of rice root decreased due to GO exposure. The relative abundance of beneficial endophytic bacterial populations decreased after GO exposure. Out of potential phenotypes predicted by BugBase, the relative abundance of Gram negative, stress-tolerant and biofilm-forming phenotypes, presented an increase trend after GO exposure.

Synthesized MoS2 nanosheets have disadvantages such as low purity (phase conversion), low stability (charge density), limited active sites and complex preparation procedures, severely hindering their applications, such as in water treatment. Herein, a facile method was designed to synthesize high-phase-purity and high-negative-charge-density solar-induced atomic-defect-rich 1T-MoS2 (S-ADR-MoS2) nanosheets. Sunlight irradiation drove the formation of atomic vacancies (diameters between approximately 0.4 and 0.9 nm; S and Mo were codeleted) in the 1T-MoS2 nanosheets by attacking ·OH and ·O2–. Consequently, S-ADR-MoS2 exhibited high selectivity and affinity for toxic metals, and 1 g S-ADR-MoS2 under 1 and 4 sun illuminations captured 638 mg and 902 mg Pb2+, respectively, which is better than the performance of most graphene-based and sulfur-functionalized nanomaterials. We demonstrated that the ionic capture of defect-rich features via strong Lewis soft − soft interactions and electrostatic attractions was the dominant mechanism for the improved Pb2+ removal capacity under sunlight irradiation. Furthermore, the layer-stacked S-ADR-MoS2 membrane achieved high water fluxes (181–345 L m−2h−1 bar−1) and a high separation performance for Pb2+ (84.5–99.6%), resulting in a Pb2+ concentration in treated water that was below the U. S. Environmental Protection Agency limits for drinking water. S-ADR-MoS2 was also able to efficiently capture other toxic metals, such as Al3+ and Cd2+, thus exhibiting high potential for the treatment of contaminated drinking water.

Alzheimer's disease (AD) is one of the most common age-associated brain diseases and is induced by the accumulation of amyloid beta (Aβ) and oxidative stress. Many studies have focused on eliminating Aβ by nanoparticle affinity; however, nanoparticles are taken up mainly by microglia rather than neurons, leading poor control of AD. Herein, mitochondria-targeted nanozymes known as (3-carboxypropyl)triphenyl-phosphonium bromide-conjugated 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000]-functionalized molybdenum disulfide quantum dots (TPP-MoS2 QDs) were designed. TPP-MoS2 QDs mitigate Aβ aggregate-mediated neurotoxicity and eliminate Aβ aggregates in AD mice by switching microglia from the proinflammatory M1 phenotype to the anti-inflammatory M2 phenotype. TPP-MoS2 QDs cross the blood-brain barrier, escape from lysosomes, target mitochondria and exhibit the comprehensive activity of a bifunctional nanozyme, thus preventing spontaneous neuroinflammation by regulating the proinflammatory substances interleukin-1β, interleukin-6 and tumor necrosis factors as well as the anti-inflammatory substance transforming growth factor-β. In contrast to the low efficacy of eliminating Aβ by nanoparticle affinity, the present study provides a new pathway to mitigate AD pathology through mitochondria-targeted nanozymes and M1/M2 microglial polarization.

The widespread use of antibiotics has accelerated the development of antibiotic resistance genes (ARGs), which are now recognized as emerging environmental contaminants that pose a high risk to public health. In this study, simultaneous antibiotic and ARGs removal and bioelectricity generation was explored in a microbial electro-Fenton system using erythromycin (ERY) as a model antibiotic compound. The results showed that ERY could be degraded, with an average removal efficiency of 88.73% in 48 h, and the average removal efficiency of chemical oxygen demand in the microbial electro-Fenton with 50 μg L−1 ERY reached 86.84% in 48 h, which was lower than that in the control group (89.11%). The produced ARGs were analyzed and degraded in a cathode chamber. The quantity of ermB was significantly reduced, with log removal reaching a value of 1.96. More importantly, all erm genes (ermB, ermC, ermG) showed a tendency to be degraded. Furthermore, the maximum power density obtained with respect to the electrode area was 0.193 W m−2 when ERY was added, corresponding to a current density of 0.583 A m−2 (external resistor = 1000 Ω), which was 14% larger than that of the control group (0.169 W m−2). The results of this study demonstrate the potential of microbial electro-Fenton for ERY and ARGs removal.

The effect of extracellular polymeric substances (EPS), vital organic matters and nutrient elements in the natural environment, on the behavior and toxicology of silver nanoparticles (AgNPs) and ions remains ambiguous. In this study, the role of EPS on the toxicity of AgNPs and dissolved silver ions (from AgNO3) to a green algae Chlorella vulgaris was investigated. After the removal of EPS, algae accumulated more silver, about 7.41- and 1.25-fold of those in the algae with EPS for AgNPs and AgNO3 treatments, respectively. The large amount of accumulated silver was bound to the algal cell surface for AgNPs treatment and was internalized in the algae for AgNO3 treatment, irrespective of the presence of EPS in algae. After exposure to AgNPs, the ruffles in the surfaces of algal cells were filled by AgNPs, and almost invisible. FTIR showed that for both AgNPs and AgNO3, the aldehyde groups on the cell surface were oxidized to carboxyl groups by silver ions, irrespective of the presence of EPS in algal cells, indicating that silver ions were released from the oxidization of AgNPs and reacted with algal cells. The content of chlorophyll showed that AgNPs depressed algal growth more remarkably than did AgNO3, independent of the presence of EPS in algae, suggesting that AgNPs had greater toxic effects on algae than did silver ions. The findings suggest that the barrier effect of EPS gave nanoparticles an extraordinary edge over ions, but EPS had no discerning effect on the interaction of algal cells with the silver ions released from AgNPs and AgNO3, and also on the effect of AgNPs and AgNO3 on algal growth.

Sewage sludge biochars (SSBCs) pyrolyzed at 300, 500, and 700 °C (denoted as SS300, SS500 and SS700) were applied for 5-day incubation with wheat to investigate the phytotoxicity of biochars and the specific mechanisms. The properties of the biochars, including the contents of 6 typical potential toxic elements (PTEs) and 16 priority polycyclic aromatic hydrocarbons (PAHs), were carefully examined. SS500 had the highest concentrations of 16 PAHs, while the total content of each PTE increased with increasing heating temperature. Wheat growth was suppressed substantially when the extract of SSBCs was applied at a concentration of 2 g/35 mL, with SS700 being the most toxic. In addition, increasing the concentration of SS700 extract led to increased toxicity. Both principal component analysis (PCA) and linear correlation analysis revealed that PTEs played an important role in determining the phytotoxicity of SSBCs. For the growth of wheat, the root length was the most sensitive to SSBC, followed by the shoot length and the seed germination. This study demonstrated that the growth of plants might be inhibited in the biochar-amended soil that highly leached throughout the years. This inhibition could be alleviated by using biochars produced at lower temperatures and by reducing the amount of biochars.

In this study, sulfamethoxazole served as the electron donor for microbial electrolysis cells. After 6 months of operation, the removal efficiencies of sulfamethoxazole in three microbial electrolysis cells were 77.60%, 87.55%, and 92.53% for a 3-day period and were directly proportional to the initial added concentrations. However, the removal efficiencies in the microbial electrolysis cells with open circuits and without microorganisms were only 51% and 8%, respectively. Higher sulfamethoxazole concentrations and sustained electrical stimulation caused faster bioelectrochemical reactions, thereby enhancing sulfamethoxazole degradation. Bacterial community analysis revealed that Proteobacteria and Synergistetes, which are the main functional phyla, proliferated with increased antibiotic concentrations. The qPCR results indicated that the copy numbers of antibiotic resistance genes and integrons in microbial electrolysis cell biofilms and effluents were distinctly lower than those in traditional biological treatment systems. Thus, the generation and dissemination of antibiotic resistance genes might be a diminished challenge in microbial electrolysis cells.

Semiconductors photocatalyst, applied in the degradation of organic pollutants in water, were summarized due to its durability, low cost, low toxicity, super-hydrophilicity, and remarkable chemical and photochemical stability. Firstly, this paper intensively summarized the photocatalytic activity of single semiconductors photocatalyst. However, single semiconductors photocatalyst showed some drawbacks that is fast recombination of electron/hole, low adsorption about visible light and low surface coverage of photocatalysts. Thus, coupling semiconductors with desirable matching electronic bandgap and doping semiconductor photocatalysts have been discussed detailly. Notably, the Ag-based semiconductor photocatalysts has been highlight. The indicators for evaluating photocatalysis properties including pollution adsorption, kinetic and recyclability were discussed in detail. In addition, the mechanisms of photocatalytic reaction were discussed, which showed the mechanism is redox reaction and the process could degrade a wide range of organic pollutants into easily degradable intermediates or less toxic small molecular substances.

In this study, more than 85.1% of sulfamethoxazole (SMX) could be degraded within 60 h. The strengthening of microbial metabolisms and the sustainment of electrical stimulation contributed to the rapid removal of SMX in microbial fuel cells (MFCs). High-performance liquid chromatography identified that SMX could be thoroughly degraded into less harmful alcohols and methane after the MFC processing. In addition, the major role of Shewanella sp. and Geobacteria sp. in power generation, and the promotion of Alcaligenes, Pseudomonas and Achromobacter in SMX degradation have been demonstrated. Moreover, this study further proved that the copy numbers of targeted antibiotic resistance genes and integrons produced in MFCs were much lower than those found in conventional wastewater treatment plants; MFCs seem to be a promising alternative to reduce antibiotics in wastewater treatment and water purification.

Anaerobic digestion (AD) reactors often encounter low pH inhibition during startup and high organic loading periods. The use of a large amount of NaOH in order to raise and buffer the low pH, is reported to be inhibitory to methanogens. In order to address this problem, we acclimatized aceticlastic methanogens to low pH. Methanogens were successfully acclimatized to initial low pH down to 3.5 in a lengthy, five months, acclimatization period. The aceticlastic methanogen, Methanothrix soehngenii which was 96.3% of the total methanogenic population at pH 4.5 and 86.75% at pH 3.5, demonstrated that they were the most tolerant aceticlastic methanogens to low pH. After acclimatization, methane yield at pH 4.5 was comparable to neutral pH. Methanosaeta maintained its dominance over Methanosarcina at an elevated level of acetate (66 mM), and a negative correlation was observed between them. There was a positive correlation between the CH4 content and pH.

Due to the residues of metoprolol (MET) in black wastewater, recovering phosphate as struvite (MgNH4PO4 · 6H2O) from black wastewater may pose threats to the utilization of struvite in the agricultural planting and human health. In this study, the adsorption and co-precipitation experiments of MET in the formation of struvite from synthetic black wastewater will be performed and some factors like initial MET concentration, pH values, temperatures were investigated. Results revealed that the adsorption process can be divided into rapid adsorption, fluctuation stage and steady stage, and the maximum MET adsorption quantity was 0.05029mg/g under 80ppb, 20 °C. Chemical adsorption and pseudo second-order kinetics were evident at the low concentration level. Neither Langmuir nor Freundlich isotherms fitted for the adsorption. The presence of Mg[H2O]6 2+ (Hexahydrate and magnesium ions) interfered with MET adsorption through recombining with MET, which was also determined by pH variation. The existence of MET in black wastewater would not obstruct the formation of struvite in alkaline condition generally and serious terrible influences would not be generated when using struvite as fertilizer. A vast majority of MET will stay in the solution after 3 hours’ reaction.

To study the function and mechanism of STM14_3514 gene that encoded in Salmonella pathogenicity island (SPI)-1 of Salmonella enterica serovar Typhimurium strain ATCC 14028.We constructed STM14_3514 mutant strain and a complemented strain of the mutant. Through mice experiment, attachment assays, invasion assays, macrophage replication assays, western blot, and Quantitative real-time PCR analysis (qRT-PCR), we compared the virulence of the mutant strain to that of the wild-type 14028.STM14_3514 mutant shows increased virulence to mice, and the bacterial number of STM14_3514 mutant in liver, spleen, and ileum was more abundant than that of the wild-type strain. The increased virulence of STM14_3514 mutant is caused by its elevated invasion ability to epithelial cells (2-fold and P0.05). qRT-PCR and western blot results show that STM14_3514 reduced the expression of HilA and another SPI-1invasion locus. Moreover, the repression of HilA by STM14_3514 is mediated by HilC.STM14_3514 is a negative regulator in SPI-1, which can repress HilA and SPI-1invasion locus through HilC, and possibly contribute to the repression on SPI-1 after bacterial invasion.

The environmental transformations of nanomaterials are correlated with their behaviors and ecological risks. The applications of single-layer molybdenum disulfide (SLMoS2) have rapidly developed in environmental fields, but the potential transformations and biological effects of SLMoS2 remain largely unknown. This study revealed that humic acid (HA, over 10 mg/L) induced the scrolling of SLMoS2 with light irradiation over a 56-day incubation. The colloidal stability of SLMoS2 increased, and the aggregation ratio decreased from 0.59 ± 0.07 to 0.08 ± 0.01 nm/min after HA hybridization. Besides, compared with pristine SLMoS2, the chemical dissolution rate of SLMoS2 was up to 4.6-fold faster with HA exposure. These results demonstrate that HA affects the environmental fate and transformations of SLMoS2. SLMoS2–HA possessed a significantly widened direct band gap (2.06 eV) compared with that of SLMoS2 (1.8 eV). SLMoS2 acted as an electronic acceptor from HA, resulting in the separation of electron–hole pairs. ...

It becomes increasingly concern in how to produce safe vegetable crops as human foods in the slightly and moderately contaminated agriculture soils, especially in China, a country with the largest population in the world. In recent years, the selection and breeding of low-accumulating cultivars (LACs), i.e., cultivars that accumulate specific pollutants at a level low enough for safe consumption even when grown in contaminated soil, has attracted widespread attention and been believed as an alternative choice for remediation of heavy metal-contaminated soils to ensure food safety. Thus, we summarized our studies on selection and identification of heavy metal LACs among vegetables during the last decade so as to provide possible reference value for the future studies. Moreover, the further research directions and limitations are also discussed in the chapter.

The effects of graphene oxide (GO) carbon nanomaterials on ecosystems have been well characterized, but the toxicity of GO at predicted environmental concentrations to living organisms at the protein level remain largely unknown. In the present work, the adverse effects and mechanisms of GO at predicted environmental concentrations were evaluated by integrating proteomics and standard analyses for the first time. The abundances of 243 proteins, including proteins involved in endocytosis (e.g., cltcb, arf6, capzb and dnm1a), oxidative stress (e.g., gpx4b, sod2, and prdx1), cytoskeleton assembly (e.g., krt8, krt94, lmna and vim), mitochondrial function (e.g., ndufa10, ndufa8, cox5aa, and cox6b1), Ca2+ handling (e.g., atp1b2a, atp1b1a, atp6v0a1b and ncx4a) and cardiac function (e.g., tpm4a, tpm2, tnni2a.1 and tnnt3b), were found to be notably altered in response to exposure 100 μg/L GO. The results revealed that GO caused malformation and mortality, likely through the downregulation of proteins related to actin filaments and formation of the cytoskeleton, and induced oxidative stress and mitochondrial disorders by altering the levels of antioxidant enzymes and proteins associated with the mitochondrial membrane respiratory chain. Exposure to GO also increased the heart rate of zebrafish larvae and induced pericardial edema, likely by changing the expression of proteins related to Ca2+ balance and cardiac function. This study provides new proteomic-level insights into GO toxicity against aquatic organisms, which will greatly benefit our understanding of the bio-safety of GO and its toxicity at predicted environmental concentrations.

Roxithromycin, as widely used medicine and livestock growth promoter, arouses concern because its occurrence and persistence in soil environments. However, effects of roxithromycin in higher plants are still vague. Accordingly, we hypothesized that roxithromycin-contaminated soil may exhibits ecotoxicological effects in wheat (Triticum aestivum). In this study, effects induced by a gradient concentration of roxithromycin stress (0.01, 0.1, 1, 10, and 100 mg·kg–1) was investigated in a 7-d soil test in T. aestivum. Results indicated that the specific activity of cytochrome P450 (CYP450) monooxygenase was decreased dramatically with the concentration of roxithromycin in soil. The IC50 value was 8.78 mg·kg–1 of roxithromycin. On the contrary, the growth related endpoints (i.e., the germination percentage, the biomass and the height), the content related endpoints (i.e., soluble protein content and CYP450 content), and the superoxide dismutase (SOD) activity failed to reveal the roxithromycin-induced effects. Further analysis revealed that the CYP450 monooxygenase specific activity reduction was enzymatic mechanism mediated, other than oxidative stress induced. We conclude that the soil roxithromycin declined the CYP450 monooxygenase activity in T. aestivum by the inhibition of the enzymatic mechanism. Further efforts can include, but are not limited to, investigation of joint effects induced by combined exposure of roxithromycin and the pesticides and evaluation of the similar effects in other higher plants.

Nanomaterial oxides are common formations of nanomaterials in the natural environment. Herein, the nanotoxicology of typical graphene oxide (GO) and carboxyl single-walled carbon nanotubes (C-SWCNT) was compared. The results showed that cell division of Chlorella vulgaris was promoted at 24 h and then inhibited at 96 h after nanomaterial exposure. At 96 h, GO and C-SWCNT inhibited the rates of cell division by 0.08-15% and 0.8-28.3%, respectively. Both GO and C-SWCNT covered the cell surface, but the uptake percentage of C-SWCNT was 2-fold higher than that of GO. C-SWCNT induced stronger plasmolysis and mitochondrial membrane potential loss and decreased the cell viability to a greater extent than GO. Moreover, C-SWCNT-exposed cells exhibited more starch grains and lysosome formation and higher reactive oxygen species (ROS) levels than GO-exposed cells. Metabolomics analysis revealed significant differences in the metabolic profiles among the control, C-SWCNT and GO groups. The metabolisms of alkanes, lysine, octadecadienoic acid and valine was associated with ROS and could be considered as new biomarkers of ROS. The nanotoxicological mechanisms involved the inhibition of fatty acid, amino acid and small molecule acid metabolisms. These findings provide new insights into the effects of GO and C-SWCNT on cellular responses.

The interactions between nanomaterials and cells are fundamental in biological responses to nanomaterials. However, the size-dependent synergistic effects of envelopment and internalization as well as the metabolic mechanisms of nanomaterials have remained unknown. The nanomaterials tested here were larger graphene oxide nanosheets (GONS) and small graphene oxide quantum dots (GOQD). GONS intensively entrapped single-celled Chlorella vulgaris, and envelopment by GONS reduced the cell permeability. In contrast, GOQD-induced remarkable shrinkage of the plasma membrane and then enhanced cell permeability through strong internalization effects such as plasmolysis, uptake of nanomaterials, an oxidative stress increase, and inhibition of cell division and chlorophyll biosynthesis. Metabolomics analysis showed that amino acid metabolism was sensitive to nanomaterial exposure. Shrinkage of the plasma membrane is proposed to be linked to increases in the isoleucine levels. The inhibition of cell division and chlorophyll a biosynthesis was associated with decreases in aspartic acid and serine, the precursors of chlorophyll a. The increases in mitochondrial membrane potential loss and oxidative stress were correlated with an increase in linolenic acid. The above metabolites can be used as indicators of the corresponding biological responses. These results enhance our systemic understanding of the size-dependent biological effects of nanomaterials.

Ag-CoFe2O4-graphene oxide (Ag-CoFe2O4-GO) nanocomposite was synthesized by doping silver and CoFe2O4 nanoparticles on the surface of GO, which was used to purify both bacteria and Pb(II) contaminated water. The Ag-CoFe2O4-GO nanomaterial was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), cyclic voltammetry (CV), and magnetic property tests. It can be found that Ag-CoFe2O4-GO nanocomposite exhibited excellent antibacterial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus compared with CoFe2O4, Ag-CoFe2O4, and CoFe2O4-GO composite. This superior disinfecting effect was possibly attributed to the combination of GO nanosheets and Ag nanoparticles. Several antibacterial factors including temperature, time, and pH were also investigated. It was obvious that E. coli was more susceptible than S. aureus toward all the four types of nanomaterials. The structural difference of bacterial membranes should be responsible for the resistant discrepancy. We also found that Ag-CoFe2O4-GO inactivated both bacteria in an irreversibly stronger manner than Ag-CoFe2O4 and CoFe2O4-GO. The Pb(II) removal efficiency with all the nanomaterials showed significant dependence on the surface area and zeta potential of the materials. In this work, not only did we demonstrate the simultaneous superior removal efficiency of bacteria and Pb(II) by Ag-CoFe2O4-GO but also the antibacterial mechanism was discussed to have a better understanding of the interaction between Ag-CoFe2O4-GO and bacteria. In a word, taking into consideration the easy magnetic separation, bulk availability, and irreversibly high antibacterial activity of Ag-CoFe2O4-GO, it is the very promising candidate material for advanced antimicrobial or Pb(II) contaminated water treatment.

Global environmental changes could affect forest productivity and thus organic matter input to soil via litterfall. We conducted a 9-month litter decomposition experiment to examine the effect of litter removal and addition on soil nitrogen (N) dynamics in a subtropical eucalypt forest subject to prescribed burning. Two litter treatments were applied: addition of double litter rates and without any litter addition. In situ 15N pool dilution method was used to determine soil gross N transformation rates, and δ 15N of soil inorganic N pools and their dynamics were also measured. The results showed that the addition of decomposing litters had no significant effect on soil net and gross N mineralization and nitrification rates. Soil N rates showed a pronounced seasonal pattern with higher rates in summer and lower rates in winter, which could be explained by the seasonal variation of environmental conditions such as temperature but not soil water content in this study. The soils had significantly higher δ 15N in NO3 −-N than in NH4 +-N after removing the forest floor, which might result from gaseous N losses via nitrification, denitrification and NO3 −-N leaching during the experimental period. Soil N transformations were not significantly affected by decomposing litters during the 9-month of decomposition. Our findings demonstrate that long-term studies of litter decomposition combined with repeated measurement of soil N transformation rates are needed to fully understand the seasonal patterns of soil N cycling and its response to decomposing litters in forest ecosystems.

Veterinary antibiotics introduced into soil environment may change the composition and functioning of soil microbial communities and promote the spreading of antibiotic resistance. Actual risks depend on the antibiotic’s bioaccessibility and sequestration in soils, which may vary with contact time and soil properties. We elucidated changes in the horsebean plant’s bioaccessible oxytetracycline with increasing contact time in three different soils (cinnamon, red, and brown soil) and observed discrepancy in oxytetracycline dissipation using sequential extractions with H2O-, 0.01 M CaCl2-, and Mcllvaine- in the same three soils. The results showed lower quantities of oxytetracycline with increasing contact time over 20 days than the level in freshly contaminated soils but hugely discrepant quantities among the three tested soils. In addition, aging largely reduced dissipation of H2O-, 0.01 M CaCl2-, and Mcllvaine- extracted oxytetracycline in soils before planting. However, bioturbation helped increase the H2O-, CaCl2-, and Mcllvaine- extracted oxytetracyline from cinnamon and brown soils with aging. Lastly, correlation analysis indicated that bioaccessibility of oxytetracycline significantly correlates with the total of H2O-, CaCl2-, and Mcllvaine- extracted oxytetracycline (0.676**, p

The environmental behaviors and risks associated with graphene have attracted considerable attention. However, the fundamental effects of ambient water and visible-light irradiation on the properties and toxicity of graphene remain unknown. This work revealed that hydration and irradiation result in the transformation of large-sheet graphene to long-ribbon graphene. The thickness of the treated graphene decreased, and oxides were formed through the generation of singlet oxygen. In addition, hydration and irradiation resulted in greater disorder in the graphene structure and in the expansion of the d-spacing of the structure due to the introduction of water molecules and modifications of the functional groups. Oxidative modifications with two-stage (fast and low) kinetics enhanced the number of negative surface charges on the graphene and enhanced graphene aggregation. The above property alterations reduced the nanotoxicity of graphene to algal cells by reducing the generation of reactive oxygen species, diminishing protein carbonylation and decreasing tail DNA. A comparative study using graphene oxide suggested that oxidative modifications could play an important role in inhibiting toxicological activity. This study provides a preliminary approach for understanding the environmental behaviors of graphene and avoids overestimating the risks of graphene in the natural environment.

The concentrations of total petroleum hydrocarbons (TPH), n-alkanes (n-C8 through n-C40), and 16 polycyclic aromatic hydrocarbons (PAHs) in soils were determined to assess the level of organic contamination in soils from the Da-gang Petrochemical Industry Park with several big state-run enterprises, a recent rapid flourishing park in China. The results showed that the concentration of TPH in soil was high, up to 20 ng/g-12.8478%; in particular, the content in most sites ranged from 1 to 2%. Thus, it is clear that soil environment in the Da-gang Petrochemical Industry Park has been seriously polluted by TPH according to the Nemerow pollution index method. Furthermore, the average concentration of Σ(n-C>16 through n-C34) in 30 sampling sites was above the maximum limit set for F3 under all the conditions in the Canada-wide standards for petroleum hydrocarbons (PHC CWS) with 43.33-93.33% soil samples exceeding F3 standards, and n-alkanes possessing higher concentrations were proved much abundant alkanes in this study. Besides, the predominance of even n-alkanes and lower carbon preference index (CPI) demonstrated that n-alkanes in surface soils were mainly caused by anthropogenic inputs, while the concentration of Σ16-PAHs was in the range of 1652.5-8217.3 ng/g and the BaA/(BaA + Chr) and Flu/(Flu + Pyr) ratios indicated that pyrogenic PAHs may be the dominant PAHs in most soils with the contribution of petrogenic hydrocarbons in some sites.

BACKGROUND: Bioelectrochemical remediation of soils contaminated by petroleum hydrocarbons has received increasing attention as an effective approach to remove pollution with simultaneous electricity generation. RESULTS: Here, glucose was added as a co-substrate in this system. The charge output of soil microbial fuel cells (MFCs) was enhanced by 262%, and the total petroleum hydrocarbon degradation rate increased by 200%. According to the increased dehydrogenase and polyphenol oxidase activities, the exogenetic glucose substantially activated hydrocarbon degradation bacteria (such as Alcanivorax). The Shannon–Wiener Index and richness of soil microbial community decreased after glucose addition, indicating that a selective enrichment of specific communities was imposed by glucose. Correlation analysis showed the biodiversity in soil far from the cathode was mainly determined by the concentration of petroleum hydrocarbons, while that in soil close to the cathode was dominated by the current. CONCLUSION: This study demonstrated that an exogenetic carbon source enhanced the bioelectrochemically assisted degradation of aged petroleum hydrocarbons in saline soils, providing an effective approach to remove contaminations from soil in barren areas or extreme environments. © 2015 Society of Chemical Industry Supporting information may be found in the online version of this article.

Plasmodiophora brassicae, causal agent of clubroot of crucifers, poses a serious threat to Canadian canola production. The effects of fallow (F) periods and bait crops (clubroot-susceptible canola (B) and perennial ryegrass (R)) on clubroot severity and P. brassicae resting spore populations were evaluated in five sequences: R–B, B–R, R–F, B–F and F–F. Both host and non-host bait crops reduced clubroot severity in a subsequent crop of a susceptible canola cultivar compared with fallow. Resting spore and P. brassicae DNA concentrations decreased in all treatments, but were lowest for the R–B and B–R bait crop sequences. In addition, two studies were conducted in mini-plots under field conditions to assess the effect of rotation of susceptible or resistant canola cultivars on clubroot severity and P. brassicae resting spore populations. One study included three crops of susceptible canola compared with a 2-year break of oat–pea, barley–pea, wheat–wheat or fallow–fallow. The other study assessed three crops of resistant canola, two crops of resistant canola with a 1-year break, one crop of resistant canola and a 2-year break, and a 3-year break with barley followed by a susceptible canola. The rotations that included non-host crops of barley, pea or oat reduced clubroot severity and resting spore concentrations, and increased yield, compared with continuous cropping of either resistant or susceptible canola. Growing of a susceptible canola cultivar contributed 23–250-fold greater gall mass compared with resistant cultivars.