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Previous studies have demonstrated that anaerobic digestion (AD) enhances sludge dewaterability. However, the mechanism of AD influence on digested sludge dewaterability is still not well understood. In this study, moisture distribution and bond energy were used to evaluate the influence of AD on sludge dewaterability. The change from free moisture (FM) to mechanically bound moisture (MBM) was analysed, along with degradation of organic fractions in extracellular polymeric substances (EPSs) of the sludge during AD. Results indicated that the AD process, with a 41.9% reduction in volatile solids (VS) and cumulative methane production of 283.2 mL/g VS, improved sludge dewaterability by disintegrating macro-molecular organic matter into micro-molecular matter. MBM reduction reached 7% in 40 days. Correlations between FM/MBM and extracellular protein (extra-PN) were significant (R = −0.861, p < 0.01; R = 0.869, p < 0.01). Therefore, it can be concluded that the degradation of protein in the extra-microcolony polymer (EMPS) layer results in the destruction of the bond between organic fractions and moisture. As a result, the release of mechanically bound moisture is accelerated. In addition, the moisture content, as well as the extra-PN, continued to vary when AD entered the stabilisation stage, that is, the destruction of protein in EMPS stimulated mechanically bound moisture release during AD. The results of this work provide a better understanding on the effect of AD on sludge reduction. Image 1 • Anaerobic digestion enhanced dewaterability by different state moisture migration. • 7% mechanically bound moisture reduction within 40 days of anaerobic digestion. • Extracellular protein was essential to enhance sludge dewaterability. • Moisture distribution and bond energy of sludge have good coupling properties. [ABSTRACT FROM AUTHOR]

Abstract Chronic exposure to high levels of arsenic is closely associated with nervous system disorders that harm learning, memory, and intelligence. Studies have shown that the primary characteristic of brain damage is neuronal apoptosis. Arsenic induces apoptosis in a variety of nerve cells. Therefore, substance that inhibit apoptosis promise to mitigate arsenic toxicity. Pigment epithelium-derived factor (PEDF) is widely distributed in brain tissues and has various effects on neurons, including induction of apoptosis. Our previous study suggested that PEDF might augment arsenic-induced apoptosis in rat brains. In this study of 151 adults with normal, mild, moderate, and high exposure to arsenic, the measured serum PEDF levels were 15.46 ± 5.87 ng/mL, 17.33 ± 8.22 ng/mL, 19.43 ± 9.51 ng/mL and 21.65 ± 14.46 ng/mL, respectively. Multiple linear regression analysis revealed an independent positive correlation between serum PEDF levels and arsenic exposure in drinking water. To study the underlying mechanism of arsenic-induced apoptosis, we exposed PEDF-transfected PC12 cells to NaAsO 2. We discovered that NaAsO 2- -induced mitochondrial apoptosis was enhanced in cells that over expressed PEDF. Moreover, p53 up regulated modulator of apoptosis (PUMA) gene and B-cell lymphoma 2 (Bcl-2) protein were primary factors in the progression of arsenic-induced apoptosis. Taken together, our results suggest that PEDF inhibition might mitigate arsenic toxicity to nerve cells. Graphical abstract Image Highlights • PEDF level in serum is positively correlated with arsenic exposure in drinking water. • PEDF promoted the mitochondrial apoptosis of nerve cells. • PEDF promoted the mitochondrial apoptosis induced by arsenic. [ABSTRACT FROM AUTHOR]

In this study, we prepared a novel hybrid functionalized chitosan-Al 2 O 3 @SiO 2 composite (FCAS) for removing hexavalent chromium [Cr(VI)] from aqueous system. Spectroscopic studies like Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy dispersive spectroscope (EDS) were characterized. The effects such as dosage of adsorbent, pH, contact time and initial Cr(VI) concentration were evaluated. It has been illustrated that a wide acidic condition in the pH range of 2–6 was conducive to Cr(VI) adsorption and only 10 min was required to reach about 80% adsorption. Also, the adsorption properties of prepared adsorbent such as kinetics, thermodynamics and isotherms were comprehensively studied. Additionally, the adsorption capacity barely declined even after five cycles. Studies found that FCAS with characteristics of high performance of adsorption rate and capacity and better reusability would be a potential adsorbent for wastewater treatment. [ABSTRACT FROM AUTHOR]

Generally, biochar plays an important role in controlling migration and accumulation of pollutants in soil. In this dissertation, biochars derived from wheat straws at various pyrolysis temperatures are used to investigate how biochar amendment affects adsorption and microbial degradation of atrazine (typical diffuse herbicide) in soils. In order to explore the influence of soil components, soil samples with different organic matter content are collected from typical agricultural sites, which are characterized as black soils in the northeast region of China. The basic sorption characteristics of biochars from wheat straws prepared at diverse pyrolysis temperature are analyzed, along with the comparisons of the sorption difference in the raw soil and soil amended with biochars at four levels of ratio (0.1%, 0.5%, 1.0% and 2.0%). By incubation experiments, atrazine degradation in non-sterile and sterile soils and effects of atrazine degradation rate after biochar amendment are also studied. Atrazine degradation is significantly enhanced in biochar amended soils, which may be because that biochar supplement can promote the growth and metabolism of microorganisms in the soil. Our findings reveal that wheatstraw- derived biochars may be effective remediation reagents for activating degradation of the soil functional microorganism and enhancing sorption of organic matter content, which can be applied to environmental-friendly accelerate the remediation of atrazine contaminated black soils. [ABSTRACT FROM AUTHOR]

Simultaneous zeolites regeneration and nitrogen removal were investigated by using a mixed solution of NaClO and NaCl (NaClO-NaCl solution), and effects of the regenerant on ammonium removal performance and textural properties of zeolites were analyzed by long-term adsorption and regeneration operations. Mixed NaClO-NaCl solution removed more NH 4 + exchanged on zeolites and converted more of them to nitrogen than using NaClO or NaCl solution alone. Response surface methodological analysis indicated that molar ratio of hypochlorite and nitrogen (ClO − /N), NaCl concentration and pH value all had significant effects on zeolites regeneration and NH 4 + conversion to nitrogen, and the optimum condition was obtained at ClO − /N of 1.75, NaCl concentration of 20 g/L and pH of 10.0. Zeolites regenerated by mixed NaClO-NaCl solution showed higher ammonium adsorption rate and lower capacity than unused zeolites. Zeolites and the regeneration solution were both effective even after 20 cycles of use. Composition and morphological analysis revealed that the main mineral species and surface morphology of zeolites before and after NaClO-NaCl regeneration were unchanged. Textural analysis indicated that NaClO-NaCl regeneration leads to an increased surface area of zeolites, especially the microporosity. The results indicated that NaClO-NaCl regeneration is an attractive method to achieve sustainable removal of nitrogen from wastewater through zeolite. [ABSTRACT FROM AUTHOR]

Marine fish living in estuaries and coastal areas commonly encounter the stress of both salinity and metal pollution. In this study, euryhaline rabbitfish Siganus oramin were exposed to 50 μg L −1 waterborne Cu or 300 μg g −1 dry wt dietary Cu at salinity 33‰, 25‰, 20‰, 10‰, and 5‰ for 30 days. The Cu accumulation in the liver (>20-fold increase) and intestine (>5-fold increase) significantly increased after either waterborne or dietary Cu acclimation. Moreover, Cu accumulation was further enhanced in the liver, intestine, plasma, and whole body of Cu-exposed fish at lower salinities. Similarly, the waterborne Cu uptake rate constants ( k u s) were stable in the control at different salinities but increased significantly (2–4 times higher) after waterborne Cu exposure. Conversely, the dietary Cu assimilation efficiencies (AEs) were significantly lower in the dietary Cu-exposed fish (3–5%) than in the control fish (8–16%) at different salinities, suggesting that dietary Cu acclimation partially alleviated the dietary Cu uptake from the high-Cu diet. The Cu efflux rate constants ( k e s) were comparable among all treatments as 0.060–0.071 d −1 . The changes of Cu accumulation by different salinities and Cu exposure were well estimated by the biokinetic modeling. In summary, the present study indicates that rabbitfish can regulate Cu uptake and accumulation when acclimated to different salinities, but the Cu-exposed rabbitfish failed to prevent the elevation of Cu accumulation at low salinities. It therefore suggested that the concurrence of low salinity and high Cu exposure enhances the risks of Cu bioaccumulation and toxicity in rabbitfish. [ABSTRACT FROM AUTHOR]

Decabromodiphenyl ether (BDE209) and lead (Pb) are the two common contaminants at e-waste recycling sites (EWRSs). A laboratory incubation study was conducted to explore the impacts of a step and repeated BDE209-Pb exposures on accumulation and metabolism of BDE209 in earthworms Eisenia fetida for the first time. The results indicated that BDE209 concentrations in repetitively-polluted soils were clearly higher. And the existence of high-level Pb could promote the bioaccumulation of BDE209 in earthworms along the exposure time. The post-clitellum contents of BDE209 were more than the pre-clitellum during the entire incubation. Additionally, GC/MS analysis results demonstrated that BDE206, BDE208, BDE153, BDE99, BDE47 and BDE28 could be detected in Eisenia fetida throughout 28-d experiment, and BDE206 and BDE208 were predominant metabolic products. A step exposure decreased the capability to metabolize BDE209 in the presence of Pb. Average bioaccumulation factor (BAF) for a step treatment was 0.525, as well as it was more than 1.1 times that of repeated exposure (BAF = 0.48). SEM observations suggested that a step exposure mode aggravated the damage in earthworms than repeated exposure. The results and related findings will establish a useful scientific basis for soil ecological risk assessment at EWRSs. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO), which is widely applied for ultraviolet-light driven photocatalysis, has no activity in visible-light photocatalytic process due to its large band gap of ∼3.2 eV. Herein, however, we demonstrated the multiple self-promotion effects of tetracycline as band adjuster, photo-sensitizer, and charge transfer promoter for ZnO nanorods, realizing its visible-light photocatalytic degradation with an excellent removal efficiency up to 91.1% within only 2 h. Besides, the influence of complex realistic factors on this unique process was evaluated together with tests with realistic water matrices. Furthermore, the active species and degradation products were identified. Both acute and developmental toxicities were found to be reduced as the degradation proceeds. These results pave the path for the brand-new self-driven visible-light photocatalysis. [Display omitted] • It is the first time to report visible-light photo-degradation of TC over ZnO. • TC acts as reactant, band adjuster, photo-sensitizer, and charge transfer promoter. • Photo-degradation of various antibiotics was comparatively studied. • Reaction pathway was revealed with toxicity reduced as degradation proceeds. • This process shows a great promise for practical application. [ABSTRACT FROM AUTHOR]

Bacteria within a metacommunity could be partitioned into different subcommunities ecological assemblages in light of potential importance for the community function. It is unknown how abundant and rare microbial subcommunities in urban river sediments respond to heavy metal pollutants. Using high-throughput sequencing, we analyzed these response patterns in the heavliy polluted (Beijing, China). We found that this river faces substantial ecological risks, owing to high rates of Cd and Hg pollution from urban activities. Surprisingly, abundant and rare subcommunity structures showed opposite responses to heavy metals. Abundant taxa, such as Crenarchaeota and Euryarchaeota, are resistant to heavy metal pollution through the synergistic of ammonia nitrogen (NH 4 +-N) and total phosphorus (TP). By contrast, rare taxa, such as Verrucomicrobia, Fibrobacteres, Berkelbacteria, and Euryarchaeota, had a high synergy with NH 4 +-N and TP with high a resilience to heavy metal pollution. However, the functions of both abundant and rare subcommunities showed a similar response to heavy metal pollutants, especially in denitrification processes. The abundant taxa responded to heavy metal pollution through methanogenesis by CO 2 reduction with H 2 , human pathogens nosocomia, sulfate respiration, photoheterotrophy, and dark sulfide oxidation synergy with NH 4 +-N and TP. The rare taxa responded to heavy metals through methanogenesis by CO 2 reduction with H 2 , cellulolysis, sulfate respiration, intracellular parasites, nitrate reduction and plant pathogen. We observed distinct patterns between the structural and functional responses of microbial subcommunities to heavy metal pollutants. Our findings support the concept that denitrification processes are sensitive to but not inhibited by high levels of heavy metals pollution. We propose that the structures and functions of the abundant and rare microbial subcommunities could inform the management of pollutants in heavily polluted urban river ecosystems at fine geographical scales. [Display omitted] • Distinct structural strategies with similar functional responses of subcommunities. • Abundant subcommunity structures had significant positive correlation to heavy metals. • Rare subcommunity structures exhibited an opposite trend. • Similar functional responses to heavy metal pollutant exist in subcommunities. • Denitrification process are sensitive to heavy metal pollution but are not inhibited. [ABSTRACT FROM AUTHOR]

In this work, a systematical investigation on the role of hydrogen sulfide (H 2 S) on the transformation of tetrachloro- p -benzoquinone (TCBQ) under ultraviolet (UV) irradiation (at 253.7 nm) in aqueous solution has been conducted through quantum chemical calculations. Under the UV irradiation, with the forward energy barrier (E a,f , 11.7 kcal mol−1) much lower than the reverse one (E a,r , 22.3 kcal mol−1), the first triplet state of TCBQ was kinetically feasible to react with bisulfide anion (HS−) via the Michael addition, and the addition of HS− could promote the release of Cl− and the formation of primary dechlorination product (HS-TriCBQ). During the UV photolysis of the primary dechlorination products (HO-TriCBQ and HS-TriCBQ) in the presence of H 2 O and H 2 S, the addition of nucleophile (OH− or HS−) to the ortho-position of the hydroxyl or thiol group might be the most efficient pathway for the dechlorination, and their respective E a,f were 9.2 kcal mol−1 (for HS−-hydroxyl), 1.1 kcal mol−1 (for OH−-thiol) and 8.9 kcal mol−1 (for HS−-thiol). Moreover, the electron transfer from HS− to the first triplet states could generate hydrosulfide radical for the dechlorination of TCBQ. The findings in the present study may provide some important theoretical foundation for the dehalogenation of TCBQ as well as other halobenzoquinones. [Display omitted] • The first triplet state of tetrachloro- p -benzoquinone and HS− could generate hydrosulfide radical. • The nucleophilic attack of HS− could facilitate the dechlorination of tetrachloro- p -benzoquinone. • The dechlorination of tetrachloro- p -benzoquinone and the decontamination of H 2 S was synergistic. [ABSTRACT FROM AUTHOR]

Arsenic (As) is well known to be biodiminished along marine food chains. The marine herbivorous fish at a lower trophic level are expected to accumulate more As. However, little is known about how marine herbivorous fish biotransform the potential high As bioaccumulation. Therefore, the present study quantified the biotransformation of two inorganic As species (As(III) and As(V)) in a marine herbivorous fish Siganus fuscescens following dietborne exposure. The fish were fed on As contaminated artificial diets at nominal concentrations of 400 and 1500 μg As(III) or As(V) g −1 (dry weight) for 21 d and 42 d. After exposure, As concentrations in intestine, liver, and muscle tissues of rabbitfish increased significantly and were proportional to the inorganic As exposure concentrations. The present study demonstrated that both inorganic As(III) and As(V) in the dietborne phases were able to be biotransformed to the less toxic arsenobetaine (AsB) (63.3–91.3% in liver; 79.0%–95.2% in muscle). The processes of As biotransformation in rabbitfish could include oxidation of As(III) to As(V), reduction of As(V) to As(III), methylation to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), and subsequent conversion to AsB. These results also demonstrated that AsB synthesis processes were diverse facing different inorganic As species in different tissues. In summary, the present study elucidated that marine herbivorous fish had high ability to biotransform inorganic As to the organic forms (mainly AsB), resulting in high As bioaccumulation. Therefore, marine herbivorous fish could detoxify inorganic As in the natural environment. [ABSTRACT FROM AUTHOR]

Lead (Pb) and decabromodiphenyl ether (BDE209) are the main pollutants at e-waste recycling sites (EWRSs). Focus on joint toxicological effects of the two chemicals has increasingly gained a great amount of interest. Therefore, the lab study was performed to determine the Pb mobility and microbial toxicity in a Pb-polluted soil in the presence of BDE209 for the first time. The results showed that BDE209 was barely degraded and could elicit the combined effects with Pb exposure during the entire incubation period. The exchangeable (EXCH) and carbonates fractions of Pb were transformed to organic, Fe/Mn oxides and residual fractions, and the addition of an appropriate amount (100 mg kg −1 ) of BDE209 facilitated the transformation compared with Pb alone. In addition, soil microbial biomass C ( C mic ), soil basal respiration (SBR) and metabolic quotient (qCO 2 ) increased in the beginning of the experiment and then declined with the incubation period extension, and BDE209 addition might cause notable different response relative to the control. Significant correlations between EXCH or mobility factor (MF) of Pb and SBR, C mic , or qCO 2 in soil treated with BDE209 can be clearly observed. Results of the observations provide a better understanding of ecotoxicological effects of Pb and BDE209 joint exposure on indigenous microorganisms in soil at EWRSs. [ABSTRACT FROM AUTHOR]

Antibiotic resistance occurrences and proliferation in activated sludge have attracted more and more attention nowadays. However, the role which extracellular polymeric substance (EPS) plays on the antibiotic resistance is not clear. The changes and correlation among EPS, tetracycline (TC) resistant bacteria (TRB) and TC resistance genes (TRGs) of sequencing batch reactors (SBRs) were investigated. Performance of SBR without TC was compared with two other SBRs to which different amounts of TC were added. Total average EPS contents were found to increase significantly from 66 mg g −1 VSS to 181 mg g −1 VSS as the TC concentrations increased from 0 to 100 μg L −1 . As the EPS content increased, TRB in sludge of the three SBRs increased significantly from 10 5 to 10 6 colony forming unit mL −1 after being exposed to TC. In addition, the concentrations of three groups of TRGs (copies mL −1 ) were determined by real-time fluorescence quantitative polymerase chain reaction and followed the order: efflux pump genes > ribosome protected genes > degradation enzyme genes. The numbers of TRGs in the idle stage were larger than those in the aeration sludge. Correlation coefficients ( R 2 ) between EPS and TRB in sludge were 0.823 ( p < 0.01) while the correlation between EPS and total TRGs was poor ( R 2 = 0.463, p > 0.05). But it showed the same tendency that EPS and TRGs in sludge increased with the increasing of TC. [ABSTRACT FROM AUTHOR]

Recently, capacitive deionization (CDI) has attracted considerable interest as a potential desalination technique for seawater. It is thus desirable to develop low-cost, sustainable, and efficient electrode materials for desalination. In this study, the polyporphyrin was prepared by a one-pot reaction from biobased furan derivative, followed by activation to manufacture nitrogen-doped polyporphyrin derived porous carbons (NPPCs) for efficient capacitive deionization. In the presence of KOH as a pore activator, NPPCs exhibited cross-linked interconnected nanosphere chain-like structures inherited from the polyporphyrin backbone with coexisting mesopores and micropores, leading to extremely high specific surface area (2979.3 m2 g−1) and large pore volume (2.22 cm3 g−1). The electrochemical measurements revealed good conductivity, outstanding stability, and extraordinary specific capacitance (328.7 F g−1) of NPPCs, which can be ascribed to rich nitrogen content (8.0 at%) and high Pyrrolic nitrogen ratio. Due to their superior hierarchical porous structure and excellent electrochemical performance, the NPPC-800 electrodes presented a high salt adsorption capacity (SAC) of 35.7 mg g−1 and outstanding cycling stability in 10 mM NaCl solution at 1.2 V during the desalination tests. This work demonstrates the utilization of biobased porous carbon material will pave a prospective way in sustainable and potential applications for CDI technique. [Display omitted] • Nitrogen-doped porous carbons were fabricated from biobased polyporphyrin. • NPPCs exhibited high specific surface areas, large pore volumes and sufficient N content. • NPPCs showed excellent electrochemical specific capacitance up to 328.7 F g−1. • NPPCs electrodes enabled high salt adsorption capacity and stable desalination recyclability. [ABSTRACT FROM AUTHOR]

In this work, the UV-induced transformation of monochloro- p -benzoquinone (MCBQ) in aqueous solution has been systematically investigated through quantum chemical calculations. During the UV irradiation at 253.7 nm, the first triplet state of MCBQ (3MCBQ*) was from the intersystem crossing of its first excited singlet state (1MCBQ*). In aqueous solution, the nucleophilic attack of OH− on carbon atoms in 3MCBQ* was the central reaction. The addition of OH− to olefinic carbon atoms was much more kinetically feasible than that to carbonyl carbon atoms, even though the carbonyl carbon atoms were more positively charged. Moreover, OH− preferred to add to the ortho-position of C–Cl bond, where the unchlorinated atom was more negatively charged than the chlorinated one. The UV photolysis of the primary intermediate (HO-CBQ) was not the same as that of MCBQ. The attack of OH− on the para-position of C–Cl bond was the most efficient pathway. The addition of OH− to the chlorinated atom of 3HO-CBQ* was much more efficient than that in the case of 3MCBQ*, which reveals that more UV irradiation may promote the dechlorination. The findings in the present study may be helpful to enrich the understanding of the halobenzoquinones transformation in aqueous solution. [Display omitted] • OH− preferred to add to the unchlorinated olefinic carbon atoms of 3MCBQ*. • The addition of OH− to the chlorinated atom of 3HO-CBQ* was much more efficient. • The unchlorinated and chlorinated atoms were similar to those in p -BQ and TCBQ. [ABSTRACT FROM AUTHOR]

Thus far, the effect of environmental antibiotics exposure to offspring's growth remains unclear. Here we aimed to evaluate whether and to what extent environmental antibiotics exposure is associated with fetal and postnatal growth. A total of 735 pregnant women and their full-term offspring from the Shanghai Obesity Birth Cohort were involved in the study. Maternal urine specimen was collected during the third trimester, and urinary concentration of fifteen environmental antibiotics was measured by liquid chromatography-tandem mass spectrometry and enzymatic method. Children were followed at birth, 12, 24 and 60 months, and growth parameters of the weight and height of children were recorded. Linear regression model was applied, and it was found that maternal veterinary antibiotic (VA) concentration was negatively associated with birth weight and ponderal index [per natural-logarithm (ln)-unit: adjusted β (95% confidence interval, CI) = – 42.1 (– 74.0, – 10.3) for birth weight, –0.11 (– 0.19, – 0.02) for birth weight z-score, and – 0.03 (– 0.05, – 0.002) for ponderal index]. Regarding specific VA, each ln-unit increment of florfenicol concentrations was likely to be associate with 39.7 g (95%CI: – 69.3, – 10.1) reduced birth weight, 0.10 (95%CI: – 0.18, – 0.02) reduced birth weight z-score, and 0.02 g/cm3 (95%CI: – 0.04, – 0.00) reduced ponderal index. Ciprofloxacin, a preferred-as-veterinary antibiotic, showed a similar dose-response relationship with neonatal anthropometric parameters to florfenicol. However, these adverse effects diminished as children grew up to 12-, 24- and 60-month-old. Larger prospective cohort studies and animal experiments are warranted to verify the hypothesis that environmental antibiotics exposure in early life, even at low doses, may cause fetal growth restriction. [Display omitted] • Nearly three quarters of fetuses were exposed to low-dose veterinary antibiotics. • Prenatal veterinary antibiotics exposure may be inversely associated with birth weight. • Ciprofloxacin and florfenicol were the main contributors to the decreased fetal growth. • The adverse effects of veterinary antibiotics diminished as children grew up. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pb addition can affect BDE209 bioaccumulation compared with exposure to BDE209 alone. [•] High level of Pb exposure can facilitate the uptake of BDE209 through the skin. [•] The elimination of BDE209 in earthworms augmented after 21d in all the treatments. [•] BDE209 can be debrominated to different products in earthworms in the presence of Pb. [Copyright &y& Elsevier]

Abstract: Cadmium selenium (CdSe) quantum dots (QDs) are semiconductor nanocrystals that hold wide range of applications and substantial production volumes. Due to unique composition and nanoscale properties, their potential toxicity to aquatic organisms has increasingly gained a great amount of interest. However, the impact of CdSe QDs exposure on zebrafish embryo and larvae remains almost unknown. Therefore, the lab study was performed to determine the developmental and behavioral toxicities to zebrafish under continuous exposure to low level CdSe QDs (0.05–31.25mgL−1) coated with mercaptopropionic acid (MPA). The results showed MPA–CdSe exposure from embryo to larvae stage affected overall fitness. Our findings for the first time revealed that: (1) The 120h LC50 of MPA–CdSe for zebrafish was 1.98mgL−1; (2) embryos exposed to MPA–CdSe resulted in malformations incidence and lower hatch rate; (3) abnormal vascular of FLI-1 transgenic zebrafish larvae appeared after exposure to MPA–CdSe including vascular junction, bifurcation, crossing and particle appearance; (4) larvae behavior assessment showed during MPA–CdSe exposure a rapid transition from light-to-dark elicited a similar, brief burst and a higher basal swimming rate; (5) MPA–CdSe induced embryos cell apoptosis in the head and tail region. Results of the observations provide a basic understanding of MPA–CdSe toxicity to aquatic organisms and suggest the need for additional research to identify the toxicological mechanism. [Copyright &y& Elsevier]

Roadway runoff derived polynuclear aromatic hydrocarbons (PAHs) impact the quality of surface and ground water. Inexpensive aspen wood fibers have been investigated as a means to remove dissolved PAH under laboratory conditions. Our isotherm experiments demonstrated that the uptake of naphthalene, fluorene, anthracene, and pyrene required up to 12.5 days to reach equilibrium. Aspen wood–water sorption coefficients, Kww, were linearly correlated to octanol–water partition coefficients and the molecular weight of the studied PAH compounds. The correlation between Kww and molecular weight was the most significant. Column experiments were carried out to study the sorption and desorption of fluorene, anthracene, and pyrene under dynamic conditions. The results indicate linear sorption, but non-linear desorption behavior. The degree of desorption was inversely correlated to a compound’s hydrophobicity. Flow interruption experiments showed that sorption and desorption was rate limited. A mass balance of the sorption and desorption tests indicated that sorptive uptake exceeded desorptive release over a given number of pore volumes. Further, absolute mass-removal efficiency increased with the molecular weight and hydrophobicity of the PAH compound. Batch and column studies demonstrated that aspen wood has the potential to become an effective remedial agent for PAH in stormwater runoff or other PAH contaminated waters. [Copyright &y& Elsevier]

Biofertilizers can replace chemical fertilizers to promote the plant growth without causing any pollution. The study of hydrogen-oxidizing bacteria (HOB) enrichment as biofertilizers from mixed culture is scarce. Our recent study shows that biofertilizing HOB are successfully enriched in a short hydraulic retention time of 10 h. While, the mechanism is unknown. This study intentionally used a two-stage method to enrich biofertilizing HOB specifically with nitrate as nitrogen source in Stage 1 and then 1-aminocyclopropane-1-carboxylate (ACC) as nitrogen source in Stage 2. It was found Pseudomonas (34.46%, reported HOB) predominated in Stage 1, while Azospirillum (59.35%), Azoarcus (36%) were dominant genera and Azospirillum lipoferum strain DSM 1691 (50%), Azoarcus olearius strain DQS-4 (50%) were dominant species in Stage 2. The enriched HOB of Stage 2 showed ACC deaminase activity. Furthermore, they could also fix N 2 and consume Ca 3 (PO 4) 2. Thus, the two-stage method can be used as a specific enrichment for HOB as biofertilizers, which extends the application of HOB in agriculture. Image 1 • Two-stage method is feasible to enrich HOB as biofertilizers in mixed culture. • HOB predominate in Stage 1 with nitrate as nitrogen source. • HOB as biofertilizers dominate in Stage 2 with ACC as a selection pressure. • The ACC deaminase activity of enriched HOB is 58.4 nmol a-ketobutyrate/mg/h. • Enriched HOB have the ability of nitrogen fixation and phosphate solubilization. [ABSTRACT FROM AUTHOR]

In the present work, talc (a low-cost clay) encapsulated salts alginate (TAL) beads were synthesized by cross-linking with lanthanum ion and tested for phosphate adsorption. Multiple methods were applied for the characterization of composites. The combined effect of talc and lanthanum improved phosphate removal performance of TAL beads. Factors such as talc content, La3+ concentration, adsorbent dosage, pH, co-existing ions (Cl−, NO 3 − and SO 4 2−) were studied in batch experiments. The optimized TAL-7 beads exhibited satisfactory selectivity towards phosphate in the coexistence of competing anions and could remain efficient phosphate removal in the pH range of 4–6. The phosphate removal efficiency reached to 95% with a maximum uptake of 16.4 mg P/g obtained at the optimal pH 4. Further experiments suggested that Langmuir isotherm model and the pseudo-second-order kinetic model could well describe the phosphate adsorption process of TAL-7 beads. Moreover, TAL-7 beads exhibited superior phosphate fixation performance in the long-term experiment. The results from adsorption experiment and characterization analysis demonstrated that TAL-7 beads could be a cost-effective and promising biosorbent for phosphate adsorption and fixation in the aqueous environment. Image 1 • The talc/alginate/lanthanum (TAL) beads were firstly synthesized and characterized. • Enhanced removal and selective sorption of phosphate were obtained by optimized TAL. • This novel adsorbent exhibited satisfactory phosphate fixation performance. • Electrostatic interaction and ligand exchange were the main adsorption mechanisms. [ABSTRACT FROM AUTHOR]

The effectiveness of rice waste biochars on heavy metal and metalloid abatement and detoxification was investigated using comprehensive studies based on As and Cd immobilization, bioaccumulation in tubifex, and microbial community changes in contaminated sediment. The remediation effects of biochars produced at different pyrolytic temperatures (400–700 °C) were evaluated. Bioaccumulation of heavy metal and metalloid in the tubifex tissue and change of indigenous microbial community under treatment of different biochars were assessed. Biochars produced at 700 °C exhibited greater effect on decreasing the concentrations of As and Cd in aqueous phase, and TCLP extractable and bioavailable metal(loid) in solid phase of sediment. The concentration of As and Cd in water phase decreased by 26%–89% and 22%–71% under the treatment of straw biochar, and decreased by 13%–92% and 5%–64% under the treatment of rice husk biochar, respectively. As and Cd contents in the tubifex tissue were positively correlated with their concentrations in aqueous phase. High-temperature biochars significantly reduced metal(loid) bioaccumulation in tubifex. The richness and biodiversity of microbial community were both greater in all biochars remediated sediment compared to non-treated sediment. These results indicated that rice waste biochars could effectively inhibit the bio-availability and toxicity of heavy metal and metalloid in sediment, and the higher-temperature biochar exhibited better performance. Image 1 • Rice waste biochars were effective for metals abatement and detoxification in sediment. • High-temperature biochars exhibited greater effect on heavy metal immobilization. • High-temperature biochars reduced heavy metal bioaccumulation in Tubifex tubifex. • Biochars could increase the microbial richness and biodiversity of sediment. [ABSTRACT FROM AUTHOR]

Chemical perturbation of pore-water in porous media may remobilize and release deposited colloids/nanomaterials into bulk flow. This re-entrainment process is important to accurately assessing the fate and transport of colloids/nanomaterials in the subsurface. This study investigated deposition and subsequent release of carboxylated graphene nanomaterials (CG) in water-saturated sand columns by first depositing CG at 100 mM NaCl or 2 mM CaCl 2 (Phase 1), followed by Phase 2 (elution with sequences of 50, 10, and 1 mM NaCl, or sequences of 0.5 and 0.1 mM CaCl 2), and then Phase 3 elution using deionized water. Approximate 89.2%–98.7% of injected CG was retained in sand through Derjaguin-Landau-Verwey-Overbeek (DLVO) interactions, Ca2+ bridging, and straining in Phase 1. Sequential reduction of ionic strength in Phases 2 and 3 resulted in increased release of deposited CG mainly due to the expansion of the electrical double layer thickness and thus decreased depth of the attractive secondary minimum. With increasing pulses of flushing solution, unrecoverable CG increased because weakly associated CG via the secondary minimum was likely translated to immobile regions. Significant tailing of CG released in Phase 3 suggests that CG retained in CaCl 2 was more resistant upon detachment than in NaCl. In cation exchange experiment, only 0.7% of applied CG was released, possibly ascribed to the CG remobilized by cation exchange was immediately re-entrained by the secondary minimum in 50 mM NaCl. Our findings indicate that retained nanomaterials (e.g., CG) can be remobilized and transported downward in transient solution chemistries, raising concerns about their potential migration risk to groundwater. Image 108639 • Deposition and release of CG was systematically examined under transient solution chemistry. • The CG was retained through DLVO interactions and pore-space geometry. • Decrease in solution IS induced the retained CG to remobilize and transport farther. • Release did not occur under cation exchange without subsequent IS decrease. • Unrecoverable fraction of deposited CG in sand increased with elution pulses (or time). [ABSTRACT FROM AUTHOR]