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Vegetables accumulate polycyclic aromatic hydrocarbons (PAHs) at high concentrations when grown in contaminated sites. Inoculation with PAH-degrading endophytic bacteria (EB PAH ) has been recognized as one of the most promising ways to remove PAHs from plant bodies; however, the performance of single endophytic bacteria is generally limited. This investigation used a composite of eight EB PAH to reduce the contamination and health risk posed by 16 EPA priority PAHs in vegetables including Chinese cabbage ( Brassica chinensis L.) and pakchoi ( Brassica campestris L.). Composite EB PAH have strong PAH degradation abilities, and more than 65% of ∑ PAH were degraded after 10-day insuspension with composite EB PAH . Vegetable were contacted with composite EB PAH by seed soaking (SS) and leaf painting (LP) with an EB PAH cell incubation at OD 600 nm = 0.2–1.5. Compared with those in non-inoculated controls, the ∑ PAH concentrations in edible parts of Chinese cabbage and pakchoi colonized by composite EB PAH via SS and LP with bacterial suspension at OD 600 nm = 0.2–1.5 were 42.07–70.77% and 15.79–53.20% lower, and the incremental lifetime cancer risk (ILCR) values for males and females were 31.78–84.08% and 26.60–83.40% smaller, respectively. SS was the optimal inoculation method for reducing PAH concentrations and ILCR values. Our results indicate that inoculating plants with composite EB PAH can lower the health risk posed by vegetables contaminated with PAHs, and may be used to mitigate plant PAH contamination. [ABSTRACT FROM AUTHOR]

• We prepare the "salt-based biochars" using the "one-step sintering" technique. • SiBC and MnBC (Si and Mn modified biochar) exhibit excellent adsorption properties. • Cu(II) adsorption mechanisms by SiBC and MnBC are reviewed. Novel salt-based biochar was prepared by loading silicon (Si) on cornstalk biomass with "one-step sintering" technique. Manganese (Mn) was also used to modify biochar with the same method as a control. Surface morphology, elemental composition, crystal structure and surface area of "salt-based biochars" were analyzed by SEM + EDS, XRD, FTIR and BET, and the effects of the dosage of absorbent and pH of solution on the adsorption process were explored. Si and Mn could be successfully attached on the biochar surface as oxide forms. SiBC exhibited a dense and agglomerated surface, while MnBC was a kind of porous and rough materials. The optimal adsorption capability would realize when putting 2 g/L of biochar composites at pH = 5–6. Adsorption isotherms, adsorption kinetics, combine with FTIR and XPS were carried out to help to elaborate the adsorption mechanisms. The maximum adsorption capacity of Cu (II) was 152.61 mg/g on SiBC and it could reach at 97% of removal rate within 10 min when the concentration was 100 mg/L, while MnBC had to take 500 min to achieve the same adsorption effect, and reached 187.76 mg/g of maximum adsorption capacity. Langmuir model and pseudo-second-order model were more suitable for both SiBC and MnBC, which meant the monolayer and chemical adsorption were dominated. Surface complexation and precipitation was attributed to SiBC. Specialistic adsorption, ion exchange and intra-particle diffusion was put it down to MnBC. [ABSTRACT FROM AUTHOR]

As an element with well-known toxicity, excessive thallium (Tl) in farmland soils, may threaten food security and induce extreme risks to human health. Identification of key contamination sources is prerequisite for remediation technologies. This study aims to examine the contamination level, health risks and source apportionment of Tl in common vegetables from typical farmlands distributed over a densely populated residential area in a pyrite mine city, which has been exploiting Tl-bearing pyrite minerals over 50 years. Results showed excessive Tl levels were exhibited in most of the vegetables (0.16–20.33 mg/kg) and alarming health risks may induce from the vegetables via the food chain. Source apportionment of Tl contamination in vegetables was then evaluated by using Pb isotope fingerprinting technique. Both vegetables and soils were characterized with overall low 206Pb/207Pb. This indicated that a significant contribution may be ascribed to the anthropogenic activities involving pyrite deposit exploitation, whose raw material and salgs were featured with lower 206Pb/207Pb. Further calculation by binary mixing model suggested that pyrite mining and smelting activities contributed 54–88% to the thallium contamination in vegetables. The results highlighted that Pb isotope tracing is a suitable technique for source apportionment of Tl contamination in vegetables and prime contamination from pyrite mining/smelting activities urges authorities to initiate proper practices of remediation. Unlabelled Image • Tl and Pb contents in vegetables and rhizosphere soils are highly interrelated. • Pyrite exploitation contributes 54–88% of Tl in vegetables via binary mixing model. • Biological evaluation factors indicate increased risk by intake. • Pb isotope analysis is a powerful tool for Tl source tracing in vegetables. [ABSTRACT FROM AUTHOR]

The "targeted ecopharmacovigilance (EPV)" strategy emphasizes the control of environmental pollution by high-priority hazardous pharmaceuticals from principal pollution sources especially in areas that are high risk as a result of drug administration. We conducted a prospective empirical study to explore the possibility of using a targeted EPV intervention as an optimized management tool for the control of aquatic pollution by antibiotics, a common type of pharmaceutical residue, in a rural area in China. Because of the notably high levels of ofloxacin in the studied aquatic environment and the well-accepted environmental risks posed by fluoroquinolone residues, ofloxacin was selected as the targeted high-priority antibiotic pollutant. Based on the main sources of antibiotic pollution in the studied rural aquatic environment, which had been traced previously, a five-step targeted EPV intervention was designed and conducted from Feb 2018 to Jan 2019. The results showed that the residual levels of ofloxacin in the studied Chinese rural aquatic environment significantly decreased during the targeted EPV intervention. Importantly, the EPV measures targeting ofloxacin were found to effectively reduce the environmental pollution by other non-targeted antibiotics. The data from a survey of 45 participants (42 residents and 3 clinicians) and 12 program committee members revealed that the targeted EPV intervention was acceptable to both participants and organizers and could be used as an economical and feasible solution for addressing antibiotic pollution in aquatic environments. Unlabelled Image • Targeted EPV is an optimized management tool to control antibiotic pollution. • An empirical study of EPV targeting ofloxacin was conducted in a rural area of China. • The targeted EPV intervention was effective, economical, feasible and acceptable. [ABSTRACT FROM AUTHOR]

Abstract Conductive materials/minerals can promote direct interspecies electron transfer (DIET) between syntrophic bacteria and methanogens in defined co-culture systems and artificial anaerobic digesters; however, little is known about the stimulation strategy of carbon material on methane production in natural environments. Herein, the effect of carbon cloth, as a representative of conductive carbon materials, on methane production with incubated wetland soil was investigated. Carbon cloth significantly promoted methanogenesis. With the application of electrochemical technology, calculation of the apparent electron transfer rate constant showed that carbon cloth significantly increased electron transfer rate (ETR) compared with the control experiment in presence of cotton cloth, from 0.0017 ± 0.0003 to 0.0056 ± 0.0015 s−1. Results obtained from both stable carbon isotope measurements and application of specific inhibitor (CH 3 F) for acetoclastic methanogenesis indicated that carbon cloth obviously promoted acetoclastic methanogenesis instead of CO 2 reduction. High-throughput sequencing showed that methane production may stem from the involvement of Methanosarcina for both treatments. Our findings suggested that conductive carbon material can promote acetoclastic methanogenesis instead of CO 2 reduction in a natural environment. Graphical abstract Unlabelled Image Highlights • Carbon cloth stimulated CH 4 production in anaerobic wetland soil. • Carbon cloth significantly promoted electron transfer. • Carbon cloth did not promote CO 2 reduction to produce methane. • Acetoclastic methanogenesis potentially contributed to CH 4 production. [ABSTRACT FROM AUTHOR]

The present study analyzed road soils collected near the dismantling workshops of an e-waste recycling region in South China to determine the PBDE profiles. Farmland soils at a distance of about 2 km from the dismantling workshops were also collected to evaluate the potential dispersion and deposition of PBDEs in the surrounding environment. Total PBDE concentrations ranged from 191 to 9156 ng/g dry weight in road soils and from 2.9 to 207 ng/g dry weight in farmland soils, respectively. Three PBDE source profiles were observed from the road soils by principal component analysis, and were compared with the congener patterns in different technical products. Elevated abundances of octa- and nona-congeners were found in the “deca-” derived PBDEs as compared with the deca-BDE products. The results in this study suggest that debromination of BDE 209 may have occurred during the use of electric and electronic equipment and/or another technical formulation (Bromkal 79-8DE) was also likely the source of octa- and nona-congeners in e-wastes. Comparison of the PBDE patterns in road and farmland soils implied that the PBDEs in farmland soils have been subject to complex environmental processes. [Copyright &y& Elsevier]

The ever-increasing use of synthetic hormones, especially progestins, for medical applications has drawn growing concerns due to their potential endocrine disrupting effects that may diminish the reproductive outputs of aquatic organisms. Using mosquitofish (Gambusia affinis) as a model species, we tested whether gestodene (GES), a commonly used progestin, can alter the expressions of genes associated with sex hormone synthesis and cause ensuing changes in morphological features, courtship behaviour and oocyte development. After exposing to GES at environmentally relevant concentrations (2.96, 32.9 and 354 ng L−1) for 40 days, we found that GES, especially at 354 ng L−1, induced masculinization of female fish, indicated by the reduced body weight to length ratio and development of gonopodia (i.e. anal fins of male fish). Thus, the males showed less intimacy and mating interest towards the GES-exposed females, indicated by the reduced time spent on attending, following and mating behaviours. While oocyte development was seemingly unaffected by GES, spermatogonia were developed in the ovary. All the aforementioned masculinizing effects of GES were associated with the increased testosterone level and decreased estradiol level, driven by upregulating androgen receptor genes (Arα and Arβ). Overall, our findings suggest that progestins could undermine the reproductive potential of aquatic organisms and hence their persistence in the progestin-contaminated environment. Unlabelled Image • Female mosquitofish were used to assess the endocrine disrupting effects of GES. • Body shape was masculinized (i.e. more elongated) by GES with a gonopodium developed. • GES induced the development of spermatogonia in the ovary. • Males showed less intimacy and mating interest towards the GES-exposed females. • Elevated testosterone level via upregulation of related genes led to masculinization. [ABSTRACT FROM AUTHOR]

Root exudates could influence the bioavailability of polycyclic aromatic hydrocarbons (PAHs), provide nutrients for soil microorganisms, and affect PAH biodegradation. However, it remains unclear how a bacterial community and its PAH-degrading genes play crucial roles in PAH biodegradation and respond to root exudates. In this study, a 32-day soil microcosm study was conducted to explore the impacts of artificial and actual root exudates on PAH degradation, degrading genes, and bacterial community structure. The results showed that 10–100 mg DOC/kg artificial and actual root exudates promoted the degradation of naphthalene, phenanthrene, and pyrene in soils, and their percent removal increased initially and then decreased with the increasing root exudates. Quantitative polymerase chain reaction analysis and 16S rRNA gene high-throughput sequencing suggested that the artificial root exudates significantly promoted the Nocardioides and Arthrobacter genera, which may harbor the nidA gene (the representative PAH-degrading gene from Gram-positive bacteria). In contrast, actual root exudates significantly stimulated the Pseudomonas genus that may harbor the nahAc gene (the representative PAH-degrading gene from Gram-negative bacteria). The correlation analysis further indicated that the absolute abundance of PAH degraders and degrading genes had strong correlations with PAH degradation efficiency. Therefore, these findings suggest that root exudates enhanced PAH biodegradation probably due to increases in abundance of both PAH-degraders and their degrading genes. Unlabelled Image • A soil microcosm study was used to explore the root exudates-influenced PAH degradation. • 10–100 mg DOC/kg root exudates promoted the PAH degradation in soils. • Absolute abundance of PAH degraders and degrading genes strongly correlated to PAH degradation. • Root exudates enhanced PAH degradation due to the increased PAH-degraders and degrading genes. [ABSTRACT FROM AUTHOR]

Pollutants from navigation sector are key contributors to emission inventories of most coastal cities with heavy port activities. The use of high fuel sulfur content (FSC) bunker oil by ocean going vessels (OGVs) has been identified as a major source of sulfur dioxide (SO 2). Government authorities all over the world, including Hong Kong government, have implemented air pollution control regulations to cap FSC of fuel used by OGVs to 0.5%, from the existing 3.5%, to reduce SO 2 emissions. However, the lack of efficient screening tools to identify non-compliant OGVs has prevented effective enforcement. This study developed and evaluated an unmanned aerial vehicle (UAV)-borne lightweight (750 g) microsensor system (MSS), which is capable of measuring ship plume SO 2 , NO 2 , NO, CO 2 , CO, and particulate matter in real-time. Extensive experiments were conducted on the sensor system to evaluate its performance during laboratory and field operations. The effects of cross-sensitivity and meteorological conditions were studied and incorporated to account for the measurement conditions in dispersed ship plumes. The SO 2 to CO 2 concentration ratio-based FSC expression was formulated as per the 2016 European Union Directive and Regulations. Furthermore, the impact of plume dilution on the accuracy of FSC measurement was investigated at different stages using the MSS, with and without the UAV in both simulated conditions and real-world scenarios, maintaining a safe distance from the OGV exhaust stacks. The study demonstrates the robustness of using UAV-borne sensor system for ship emission sniffing and FSC determination. The results will assist in development of a technological framework for effective enforcement of ship emission control regulations. Unlabelled Image • Studied impacts of cross-sensitivity and meteorological changes on MSS performance. • Plume dilutions showed nominal effects on FSC estimation while using UAV-borne MSS. • FSC estimation accuracy of MSS validated by measuring predefined FSC emissions. • Airborne MSS emerges as an efficient tool for remotely screening non-compliant OGVs. • Useful in pollutant concentration ratio based assessment of varied emission sources. [ABSTRACT FROM AUTHOR]

Metal(loid) contamination caused by industrial activities in agricultural soils has become a universal environmental and food safety concern. This study revealed the contamination, pathway, and source contribution of metal(loid)s such as lead (Pb), zinc (Zn) and cadmium (Cd) in maize and soils in different residential areas impacted by long-term historical artisanal zinc smelting activities from Southwest China. Results revealed that the soils were contaminated heavily by metals like Pb, Zn and Cd, with contents of 40–14,280, 150–47,020 and 1.28–61.7 mg/kg, respectively. Hazard quotients of food uptake for Pb, Cd and Cr in maize grains were extremely high for residents, in particular for the children. To trace the sources of metal health risk, lead isotope fingerprinting and binary mixing modeling were applied. It indicated that the anthropogenic activities contributed over 80% to the Pb contamination in maize grains. The findings highlighted warning levels of health risks to the residents in consuming maize grains in the historical artisanal Pb Zn smelting area. Therefore, an effective strategy including pollution source control and remediation measures must be taken to improve the soil quality and guarantee food safety around the historical smelting areas likewise. Unlabelled Image • Maize and rhizospheric soils were heavily contaminated by Pb, Zn and Cd. • Local residents were under high intake risks for Pb, Zn, Cd and Cr. • Pb-Zn artisanal smelting contributed over 80% to the contamination in the maize grains. • Lead isotopic source tracing is critical to address metal contamination inventory. [ABSTRACT FROM AUTHOR]

Thallium (Tl) is a trace element with extreme toxicity. Widespread Tl pollution in riverine systems, mainly due to escalating mining and smelting activities of Tl-bearing sulfide minerals, has attracted increasing attention. Insights into the function of the microbial communities with advanced characterization tools are critical for understanding the biogeochemical cycle of Tl. Herein, microbial communities and their adaptive evolution strategies in river sediments from a representative Tl-bearing pyrite mine area in southern China were profiled via 16S rRNA gene sequence analysis and shotgun metagenomic analysis. In total, 64 phyla and 778 genera of microorganisms were observed in the studied sediments. The results showed that pH, Tl, Pb, Zn and total organic carbon (TOC) had a significant influence on microbial community structure. Some important reductive microorganisms (such as Erysipelothrix , Geobacter , desulfatiferula , desulfatihabadium and fusibacter) were involved in the biogeochemical cycle of Tl. The ruv , rec , ars and other resistance genes enhanced the tolerance of microorganisms to Tl. The study suggested that relevant C, N and S cycle genes were the main metabolic paths of microorganisms surviving in the high Tl-polluted environment. The findings were critical for establishment, operation and regulation in the microbial treatment of Tl containing or related wastewater. Unlabelled Image • The metabolism of microbes in high thallium (Tl) polluted sediments was insighted. • Metabolite of iron/sulfate-reducing microbes might change Tl geochemical fractions. • Resistance genes such as ruv , rec and ars may enhance the microbes' tolerance to Tl. [ABSTRACT FROM AUTHOR]

Cadmium isotopic compositions in non-contaminated systems and anthropogenic sources of Cd generally have different isotopic signatures. Cadmium isotopes, as a novel tracer, can be useful for fingerprinting the anthropogenic Cd sources, providing a promising source tracing technique in environmental studies. This review presents: (i) analytical techniques for Cd isotopic composition; (ii) isotopic signatures of Cd derived from anthropogenic activities; (iii) isotopic compositions of Cd in the industrial-impacted environmental samples; (iv) cadmium isotopic fractionation induced by geochemical process. Finally, the perspectives of using Cd isotopic compositions in environmental studies are also briefly discussed. Unlabelled Image • The analytical methods for isotopic composition of cadmium (Cd) are reviewed. • Cd isotopic compositions in major Cd pollutants are summarized. • Cd isotopes are powerful to trace pollution in different environmental systems. [ABSTRACT FROM AUTHOR]

Redox transformations of organic contaminants by bacterial extracellular polymeric substances (EPS) and the associated electron transfer mechanisms are rarely reported. Here we show that a nitroaromatic compound (1,3-dinitrobenzene) can be readily reduced to 3-hydroxylaminonitrobenzene and 3-nitroaniline in aqueous suspension of common bacteria (E. coli or B. subtilis) or in aqueous dissolved EPS extracted from the bacteria. The loss ratio of 1,3-dinitrobenzene by E. coli was unaffected after knocking out the nfsA gene encoding nitroreductase, but was suppressed by removing EPS attached to cells. In contrast, the loss ratio was enhanced by adding aqueous dissolved EPS to E. coli or B. subtilis suspension. The residual 1,3-dinitrobenzene and products formed after reduction were only presented outside the bacterial cells. Thus, bacterial reduction of 1,3-dinitrobenzene was mediated by nonenzymatic extracellular reduction. This was further corroborated by the observation that the stoichiometric demand of electrons in 1,3-dinitrobenzene reduction was nearly equal to the quantity of electrons donated by bacterial cells in the electrochemical cell experiment. Inhibition on the reduction of 1,3-dinitrobenzene by chemical probes combined with fluorescence detection demonstrated that reducing sugars in EPS might act as electron donors, while cytochromes and some low-molecular weight molecules (flavins and quinones) were involved as electron transfer mediators. Linear relationships were observed between the reduction kinetics and the one-electron reduction potentials for a series of substituted dinitrobenzenes in the presence of bacterial cells or dissolved EPS. Their close linear regression slope values suggest that the extracellular matrix and the exfoliated EPS utilized the same reducing agents (likely hydroquinones and reduced flavins) as terminal electron donors to reduce NACs. These results reveal a previously unrecognized mechanism for nonenzymatic extracellular reduction of NACs by common bacteria. The extracellular matrix of E. coli or B. subtilis supplies both electron donors and electron transfer mediators to efficiently reduce nitroaromatic compounds. Unlabelled Image • Bacterial suspensions of E. coli or B. subtilis can readily reduce NACs. • Reduction of NACs occurs predominantly within the extracellular matrix. • Hemiacetal groups in EPS serve as the primary electron donor agents. • Cytochromes, flavins and quinones in EPS serve as electron transfer mediators. • Reduction of NACs is nonenzymatic and driven by extracellular electron transfer. [ABSTRACT FROM AUTHOR]

Farmland soil contamination of heavy metal(loid)s (HM) derived from smelting activities is a global concern, owing to its potential threat for human health through food chain. This study aims to evaluate total contents and bioavailability of HMs (Pb, Zn, Tl, Cd, Cu, As, Ag, Co, Cr and Ni) in farmland soils distributed over ten different villages from a former artisanal zinc smelting area in the northwest Guizhou province, China. The results showed that most of the studied soils still exhibited exceptionally high enrichment of Pb, Zn, Cd and As. High levels of bioavailable HMs were also observed in some samples, which may enter the human food chain through agricultural activities. Further analyses by Scanning Transmission Electron Microscopy - Energy Dispersive Spectroscopy (STEM-EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) showed the presence of Zn smelting by-products such as Fe oxides, ZnO and PbSO 4 even in nanoscale particles retained by the soils. Elemental mapping by EDS confirmed a close association of the studied HMs with the smelting waste particles. All these results signify that high levels of HM-contamination from historical artisanal zinc smelting activities still persist and threaten the health of local residents, despite the fact that the major industrial-derived-contamination period ended >15 years ago. Our findings highlight pivotal concerns in similar artisanal-smelting-affected farmland soils of suspected contamination, due to less-expected toxic elements such as Tl, which may cause high ecological health risks. Unlabelled Image • The farmland soils in a historical artisanal zinc smelting area were intensively investigated. • Typical Heavy metal(loid)s in farmland soils from ten different villages were analyzed. • Most of the studied soils still exhibited exceptionally high enrichment of Pb, Zn, Cd and As. • Zn smelting derived Fe oxides, ZnO and PbSO 4 were found in nanoscale particles in the soils. • It indicates that artisanal-smelting activity may pose long-term pollution hazards. [ABSTRACT FROM AUTHOR]

Uranium (U) is a toxic and radioactive element. Excessive amounts of aqueous U(VI) generated from U mining, processing and nuclear industry may result in severe and irreversible damage to the environment. Herein, Ficus microcarpa aerial root (FMAR), a biowaste material, was used to adsorb U(VI) from aqueous solutions for the first time. Potassium permanganate (KMnO 4)-modified FMAR biochar was synthesised, characterised and compared with raw (unmodified) biochar with respect to U(VI) adsorption. The results showed that the adsorption capability of the modified FMAR biochar was evidently higher than that of the raw biochar. Multiple characterisation techniques confirmed that the discrepancy was mainly due to the increased content of O−H and formation of irregular sheet-like nanostructure with the ultrafine MnO 2 nanoparticles on the biochar surfaces after KMnO 4 modification. The abundance of O−H and nanoscale MnO 2 notably enhanced the adsorption of U(VI) by means of coordination and Lewis acid-base interaction. The results indicate that KMnO 4 -modified FMAR biochar has a good potential to serve as an environment-friendly adsorbent for the removal of U(VI) from solution. Unlabelled Image • A novel biochar was synthesised from Ficus microcarpa aerial root (FMAR) biowaste. • Ultrafine MnO 2 particles covered modified biochar after KMnO 4 modification. • The increased O H and generated MnO 2 enhanced the adsorption ability. • FMAR biochar serves as an environment-friendly adsorbent to remove U(VI). [ABSTRACT FROM AUTHOR]