Biochar-supported nanoscale zero-valent iron (nZVI) produced under different temperatures was studied to evaluate the effect of the nZVI-biochar composite on the removal of hexavalent chromium (Cr(VI)) in solution. The structure of biochar-supported nZVI and its roles in Cr(VI) removal were investigated by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and batch experiments. The XRD revealed that the removal rate of Cr(VI) for the nZVI supported by rice straw pyrolyzed at 400 °C (RS400) was much greater than that for other supporting biochar, and the FTIR further indicated that the carboxyl groups and silicon mineral within the biochar served as dual support sites for nZVI. NZVI-RS400 exhibited the highest removal amount of Cr(VI) at approximately 40.0 mg/g under an initial pH of 4.0, possibly due to both the reduction and adsorption processes. Therefore, the RS400-supported nanoscale zero-valent iron could be a preferable material for Cr(VI)-contaminated groundwater.

A systematic grid sampling method and geostatistics were employed to investigate the spatial distribution, inventory, and potential ecological and human health risks of the residues of hexachlorobenzene (HCB) and chlorinated cyclodiene pesticides in soils of the Campanian Plain, Italy, and explore their relationship with the soils properties. The geometric mean (Gmean) concentrations of HCB and cyclodiene compounds followed the order CHLs (heptachlor, heptachlor epoxide, trans-chlordane, and cis-chlordane) > DRINs (aldrin, dieldrin, and endrin) > SULPHs (α-endosulfan, β-endosulfan, and endosulfan sulfate) > HCB. The residual levels of most cyclodienes in agricultural soils were generally higher than those of corresponding counterparts in the other land uses. Significant differences in the concentration of HCB and cyclodienes in the soils across the region are observed, and the Acerra-Marigliano conurbation (AMC) and Sarno River Basin (SRB) areas exhibit particularly high residual concentrations. Some legacy cyclodienes in the Campanian Plain may be attributed to a secondary distribution. The Gmean inventory of HCB, SULPHs, CHLs, and DRINs in the soil is estimated to be 0.081, 0.41, 0.36, and 0.41 metric tons, respectively. The non-cancer and cancer risks of HCB and cyclodienes for exposed populations are deemed essentially negligible, however, endosulfan poses significant ecological risks to some terrestrial species.

2,4,6-Tribromophenol (TBP), an intermediate of brominated flame retardants, can easily release to environment and recalcitrant to degradation. Previously, Bacillus sp. GZT, a pure aerobic strain capable of simultaneously debrominating and mineralizing TBP, was successfully isolated by us. To further obtain a practical application and dig up its TBP degradation mechanism, a total of 46.7-fold purification of a novel dehalogenase with a final specific activity of 18.9 U mg−1 and a molecular mass of 63.4 kDa was achieved. Under optimal conditions (35 °C and 200 rpm), up to 80% degradation efficiencies were achieved within 120 min. Adding H2O2, NADPH, Mn2+ and Mg2+ promoted enzyme reaction effectively; while EDTA, methyl viologen, Ni2+, Cu2+, Ca2+ and Fe2+ strongly inhibited reaction activities. The debromination of TBP was catalyzed by the enzyme at a Km of 78 μM and a Vmax of 0.65 min−1 mg protein−1, which indicated that this dehalogenase could specifically eliminate TBP with a high efficiency and stability. Based on MALDI-TOF/TOF analysis, the dehalogenase shared 98% identity with peptide ABC transporter substrate-binding protein. One open reading frame (ORF) encoding this peptide was found in Strain GZT genome, subjected to clone and expressed in Escherichia coli (E. coli) to characterize the encoding gene. Result showed that this recombinant strain could also remove as similar amount of TBP as Bacillus sp. GZT under the identical condition. Based on these results, we suggest that this newly-isolated TBP dehalogenase highlights a new approach for remediating TBP pollution.

Benzotriazole ultraviolet stabilizers (BUVSs) are prominent chemicals widely used in industrial and consumer products to protect against ultraviolet radiation. They are becoming contaminants of emerging concern since their residues are frequently detected in multiple environmental matrices and their toxicological implications are increasingly reported. We herein investigated the antiandrogenic activities of eight BUVSs prior to and after human CYP3A4-mediated metabolic activation/deactivation by the two-hybrid recombinant human androgen receptor yeast bioassay and the in vitro metabolism assay. More potent antiandrogenic activity was observed for the metabolized UV-328 in comparison with UV-328 at 0.25 μM ((40.73 ± 4.90)% vs. (17.12 ± 3.00)%), showing a significant metabolic activation. In contrast, the metabolized UV-P at 0.25 μM resulted in a decreased antiandrogenic activity rate from (16.08 ± 0.95)% to (6.91 ± 2.64)%, indicating a metabolic deactivation. Three mono-hydroxylated (OH) and three di-OH metabolites of UV-328 were identified by ultra-performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS/MS), which were not reported previously. We further surmised that the hydroxylation of UV-328 occurs mainly at the alicyclic hydrocarbon atoms based on the in silico prediction of the lowest activation energies of hydrogen abstraction from C-H bond. Our results for the first time relate antiandrogenic activity to human CYP3A4 enzyme-mediated hydroxylated metabolites of BUVSs. The biotransformation through hydroxylation should be fully considered during the health risk assessment of structurally similar analogs of BUVSs and other emerging contaminants.

Glyphosate is one of the most used herbicides in agricultural lands worldwide. Wind-eroded sediment and dust, as an environmental transport pathway of glyphosate and of its main metabolite aminomethylphosphonic acid (AMPA), can result in environmental- and human exposure far beyond the agricultural areas where it has been applied. Therefore, special attention is required to the airborne transport of glyphosate and AMPA. In this study, we investigated the behavior of glyphosate and AMPA in wind-eroded sediment by measuring their content in different size fractions (median diameters between 715 and 8 μm) of a loess soil, during a period of 28 days after glyphosate application. Granulometrical extraction was done using a wind tunnel and a Soil Fine Particle Extractor. Extractions were conducted on days 0, 3, 7, 14, 21 and 28 after glyphosate application. Results indicated that glyphosate and AMPA contents were significantly higher in the finest particle fractions (median diameters between 8 and 18 μm), and lowered significantly with the increase in particle size. However, their content remained constant when aggregates were present in the sample. Glyphosate and AMPA contents correlated positively with clay, organic matter, and silt content. The dissipation of glyphosate over time was very low, which was most probably due to the low soil moisture content of the sediment. Consequently, the formation of AMPA was also very low. The low dissipation of glyphosate in our study indicates that the risk of glyphosate transport in dry sediment to off-target areas by wind can be very high. The highest glyphosate and AMPA contents were found in the smallest soil fractions (PM10 and less), which are easily inhaled and, therefore, contribute to human exposure.

Data on fine particulate matter (PM2.5) in China were first announced in 2013. The primary objective of this study was to evaluate the acute effects of PM2.5 on asthma morbidity in Beijing, China. A total of 978,658 asthma hospital visits consisting of 928,607 outpatient visits, 40,063 emergency room visits and 9988 hospital admissions from January 1, 2010, to June 30, 2012, were identified from the Beijing Medical Claim Data for Employees. A generalized additive Poisson model was applied to explore the association between PM2.5 and health service use. The mean daily PM2.5 concentration was 99.5 μg/m3 with a range from 7.2 μg/m3 to 492.8 μg/m3. Ambient PM2.5 concentration was significantly associated with increased use of asthma-related health services. Every 10 μg/m3 increase in PM2.5 concentration on the same day was significantly associated with a 0.67% (95% CI, 0.53%–0.81%), 0.65% (95% CI, 0.51%–0.80%), and 0.49% (95% CI, 0.35%–0.64%) increase in total hospital visits, outpatient visits and emergency room visits, respectively. The exposure–response association between PM2.5 concentration and hospital visits for asthma exacerbations was approximately linear. In conclusion, this study found that short-term elevations in PM2.5 concentration may increase the risk of asthma exacerbations. Our findings contribute to the limited scientific literature concerning the acute effects of PM2.5 on asthma morbidity outcomes in developing countries.

Disinfectant used in drinking water treatment and distribution system can induce culturable bacteria, including various kinds of pathogenic bacteria, into viable but non-culturable (VBNC) state. The loss of cultural state, resuscitation and environmental persistence of VBNC bacteria will severely damage drinking water microbiological safety and thus pose a risk to public health. The manner in which chlorination treatment induced a VBNC state in Escherichia coli and the antibiotic persistence of VBNC bacteria was investigated. It was found that low dosage of chlorine (0.5 mg L−1) disinfection effectively reduced the culturability of E. coli and induced a VBNC state, after which metabolic activity was reduced and persistence to 9 typical antibiotics was enhanced. Furthermore, RT-qPCR results showed that stress resistance genes (rpoS, marA, ygfA, relE) and ARGs, especially efflux genes were up-regulated compared with culturable cells. The intracellular concentration was tested and found to be lower in VBNC cells than in actively growing E. coli, which suggested a higher efflux rate. The data presented indicate that VBNC E. coli are more persistent than culturable counterparts to a wide variety of antibiotics. VBNC E. coli constitute a potential source of contamination and should be considered during monitoring of drinking water networks.

The 22ⁿᵈ Asia-Pacific Economic Cooperation (APEC) Conference was held near Yanqi Lake, Huairou, in Beijing, China during November 10-11, 2014. To guarantee haze-free days during the APEC Conference, the Beijing government and the governments of the surrounding provinces implemented a series of controls. Three months of Aethalometer 880 nm black carbon (BC) measurements were examined to understand the hourly fluctuations in BC concentrations that resulted from emission controls and meteorology changes. Measurements were collected at the University of Chinese Academy of Sciences near the APEC Conference site and in Central Beijing at the Institute of Remote Sensing and Digital Earth of the Chinese Academy of Sciences. Synoptic conditions are successfully represented through analysis of backward trajectories in six cluster groups. The clusters are identified based on air mass transport from various areas such as Inner Mongolia, Russia, three northeastern provinces, and Hebei industrial areas, to the measurement sites. Air pollution control measures during the APEC Conference significantly reduced BC at the conference site (Huairou) and in Central Beijing, with greater reductions in BC concentrations at the conference site than in Central Beijing. The highest BC concentrations in Huairou were associated with air masses originating from Central Beijing rather than from the Hebei industrial region. The success of the control measures implemented in Beijing and the surrounding regions demonstrates that BC concentrations can be effectively reduced to protect human health and mitigate regional climate forcing. This study also demonstrates the need for regional strategies to reduce BC concentrations, since urban areas like Beijing are sources as well as downwind receptors of emissions.

Wheat is one of several cereals that is capable of accumulating higher amounts of Cd in plant tissues. It is important to understand the Cd²⁺ transport processes in roots that result in excess Cd accumulation. Traditional destructive technologies have limited capabilities in analyzing root samples due to methodological limitations, and sometimes may result in false conclusions. The mechanisms of Cd²⁺ uptake into the roots of wheat seedlings (Triticum aestivum L.) were investigated by assessing the impact of various inhibitors and channel blockers on Cd accumulation as well as the real-time net Cd²⁺ flux at roots with the non-destructive scanning ion-selective electrode technique. The P-type ATPase inhibitor Na3VO4 (500 μM) had little effect on Cd uptake (p < 0.05) and the kinetics of transport in the root of wheat, suggesting that Cd²⁺ uptake into wheat root cells is not directly dependent on H⁺ gradients. While, the uncoupler 2,4-dinitrophenol significantly limited Cd²⁺ uptake (p < 0.05) and transport kinetics in the root of wheat, suggesting the existence of metabolic mediation in the Cd²⁺ uptake process by wheat. The Cd content at the whole-plant level in wheat was significantly (p < 0.05) decreased upon pretreatment with the Ca²⁺ channel blockers La³⁺ or Gd³⁺ and Verapamil, but not in case of pretreatment with the K⁺ channel blocker tetraethylammonium (TEA). In addition, the inhibitors of the Ca²⁺ channel, as well as high concentrations of Ca²⁺, reduced the real-time net Cd²⁺ fluxes at the root surface in SIET experiments. These results indicate that Cd²⁺ moves across the plasma lemma of the wheat root via Ca²⁺ channels. In addition, our results suggested a role for protein synthesis in mediating Cd²⁺ uptake and transport by wheat.

The Catskill Mountains have been adversely impacted by decades of acid deposition, however, since the early 1990s, levels have decreased sharply as a result of decreases in emissions of sulfur dioxide and nitrogen oxides. This study examines trends in acid deposition, stream-water chemistry, and soil chemistry in the southeastern Catskill Mountains. We measured significant reductions in acid deposition and improvement in stream-water quality in 5 streams included in this study from 1992 to 2014. The largest, most significant trends were for sulfate (SO42−) concentrations (mean trend of −2.5 μeq L−1 yr−1); hydrogen ion (H+) and inorganic monomeric aluminum (Alim) also decreased significantly (mean trends of −0.3 μeq L−1 yr−1 for H+ and −0.1 μeq L−1 yr−1 for Alim for the 3 most acidic sites). Acid neutralizing capacity (ANC) increased by a mean of 0.65 μeq L−1 yr−1 for all 5 sites, which was 4 fold less than the decrease in SO42− concentrations. These upward trends in ANC were limited by coincident decreases in base cations (−1.3 μeq L−1 yr−1 for calcium + magnesium). No significant trends were detected in stream-water nitrate (NO3−) concentrations despite significant decreasing trends in NO3− wet deposition. We measured no recovery in soil chemistry which we attributed to an initially low soil buffering capacity that has been further depleted by decades of acid deposition. Tightly coupled decreasing trends in stream-water silicon (Si) (−0.2 μeq L−1 yr−1) and base cations suggest a decrease in the soil mineral weathering rate. We hypothesize that a decrease in the ionic strength of soil water and shallow groundwater may be the principal driver of this apparent decrease in the weathering rate. A decreasing weathering rate would help to explain the slow recovery of stream pH and ANC as well as that of soil base cations.