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Chemical compositions of fog and precipitation at Sejila Mountain in the southeast Tibetan Plateau, China
2019
Wang, Wei | Xu, Wen | Collett, Jeffrey L. | Liu, Duanyang | Zheng, Aihua | Dore, Anthony J. | Liu, Xuejun
Chemical compositions of fog and rain water were measured between July 2017 and September 2018 at Sejila Mountain, southeast Tibet, where fog events frequently occurred in original fir forests at altitude 3950 m. Fog water samples were collected using a Caltech Active Strand Cloud Collector (CASCC), and rain samples were collected using a precipitation gauge. Differences were observed between fog water and rain composition for most analyzed ions. Ion abundance in fog water was Ca²⁺ > Cl⁻ > Na⁺ > SO₄²⁻ > Mg²⁺ > NH₄⁺ >K⁺ > NO₃⁻ whereas an order of Ca²⁺ > Na⁺ > Cl⁻ > Mg²⁺ > SO₄²⁻ > NO₃⁻ > K⁺ > NH₄⁺ was observed for rain water. All ion concentrations were higher in fog water than in rain water. Additionally, Ca²⁺ was the dominant cation in both fog and rain samples, accounting for more than half of all measured cations. NH₄⁺ and SO₄²⁻ concentrations were notable for being higher in fog than rain water when compared with other ions. For trace elements, Al, As, Mn and Se were the most abundant elements in fog water; only Al and As were detected in rain water. Seventy-two hour back-trajectory analysis showed that air masses during fog and/or rain events mainly came from the south of Sejila Mountain. Spearman correlation analysis and source contribution calculations indicated that both marine and terrestrial sources contributed to the observed ion concentrations. Considering the higher concentrations of NH₄⁺ and higher ratio of NH₄⁺/NO₃⁻ measured in fog than in rain, we suggest that quantification of fog nitrogen deposition and its ecological effect in this area should be given more attention.
Afficher plus [+] Moins [-]Redox properties and dechlorination capacities of landfill-derived humic-like acids
2019
Xiao, Xiao | Xi, Bei-Dou | He, Xiao-Song | Zhang, Hui | Li, Yan-Hong | Pu, Shengyan | Liu, Si-Jia | Yu, Min-Da | Yang, Chao
Electron transfer capacities (ETC) of humic-like acids (HLA) and their effects on dechlorination are dependent on their redox-active properties. Aging and minerals can affect the chemical compositions and structures of HLA. However, the underlying mechanism and the impacts on the dechlorination capacities of HLA are poorly understood. We investigated how redox properties change in association with the intrinsic chemical natures and exterior minerals of the HLA extracted from landfilled solid wastes. Furthermore, the ETC of the landfill-derived HLA could be strengthened by increasing landfill age and demineralization, thereby facilitating the dechlorination of pentachlorophenol (PCP). The HLA molecules started to polymerize aromatic macromolecules during landfilling, leading to an increase in ETC and dechlorination capacities. Macromolecular HLA were dissociated to smaller molecules and exposed more aromatic and carboxyl groups when separated from minerals, which enhanced the ETC and the dechlorination abilities of the HLA. Microbial-mediated dechlorination was an effective way to degrade PCP, and almost 80% of the PCP was transformed after 40 days of demineralized HLA and Shewanella oneidensis MR-1 incubation. The demineralization and aging further facilitated the microbial-mediated PCP dechlorination. The findings provide a scientific base for improving in-situ bioremediation of chlorinated compound-contaminated soils using freshly synthesized HLA.
Afficher plus [+] Moins [-]Electrochemical removal of Terbuthylazine:Boron-Doped Diamond anode coupled with solid polymer electrolyte
2019
Tasca, Andrea Luca | Puccini, Monica | Clematis, Davide | Panizza, Marco
Terbuthylazine (TBA) has replaced atrazine in many EU countries, becoming one of the most frequently detected pesticides in natural waters. TBA is a compound of emerging concern, due to its persistence, toxicity and proven endocrine disruption activity to wildlife and humans. Techniques applied in water treatment plants remove only partially this herbicide and poor attention is given to the generation and fate of by-products, although some of them have demonstrated an estrogenic activity comparable to atrazine. This paper summarizes the environmental occurrence of TBA and its main metabolite desethylterbuthylazine and reports the performance of an innovative electrochemical cell equipped with a solid polymer electrolyte (SPE) sandwiched between a Ti/RuO₂ cathode and a Boron-Doped Diamond anode, operating at constant current, in the treatment of an aqueous solution of TBA. The herbicide removal in the first 30 min of treatment increases from 42% to 92% as the applied current is increased from 100 to 500 mA. The rate of degradation at 500 mA decreases between 30 and 60 min, with a final abatement of 97%. An 89% removal was reached at 100 mA when the initial TBA concentration was raised from 0.1 to 4 mg L⁻¹ and less than 1% of the herbicide was converted in desethylterbuthylazine and minor metabolites. No chemicals are needed, no sludge is produced. Further research is encouraged, as this technology may be promising for the achievement of a zero-discharge removal of different emerging pollutants as pesticides, pharmaceuticals and personal care products.
Afficher plus [+] Moins [-]Transfer of pyrrolizidine alkaloids between living plants: A disregarded source of contaminations
2019
Selmar, Dirk | Wittke, Carina | Beck-von Wolffersdorff, Iris | Klier, Bernhard | Lewerenz, Laura | Kleinwächter, Maik | Nowak, Melanie
To elucidate the origin of the wide-spread contaminations of plant derived commodities with various alkaloids, we employed co-cultures of pyrrolizidine alkaloid (PA) containing Senecio jacobaea plants with various alkaloid free acceptor plants. Our analyses revealed that all plants grown in the vicinity of the Senecio donor plants indeed contain significant amounts of the PAs, which previously had been synthesized in the Senecio plants. These findings illustrate that typical secondary metabolites, such as pyrrolizidine alkaloids, are commonly transferred and exchanged between living plants. In contrast to the broad spectrum of alkaloids in Senecio, in the acceptor plants nearly exclusively jacobine is accumulated. This indicates that this alkaloid is exuded specifically by the Senecio roots. Although the path of alkaloid transfer from living donor plants is not yet fully elucidated, these novel insights will extend and change our understanding of plant-plant interactions and reveal a high relevance with respect to the widespread alkaloidal contaminations of plant-derived commodities. Moreover, they could be the basis for the understanding of various so far not fully understood phenomena in cultivation of various crops, e.g. the beneficial effects of crop rotations or the co-cultivation of certain vegetables.
Afficher plus [+] Moins [-]CO2, CO, hydrocarbon gases and PM2.5 emissions on dry season by deforestation fires in the Brazilian Amazonia
2019
Amaral, Simone Simões | Costa, Maria Angélica Martins | Soares Neto, Turibio Gomes | Costa, Marillia Pereira | Dias, Fabiana Ferrari | Anselmo, Edson | Santos, José Carlos dos | Carvalho, João Andrade de
The rate of deforestation in Brazil increased by 29% between 2015 and 2016, resulting in an increase of greenhouse gas emissions (GHG) of 9%. Deforestation fires in the Amazonia are the main source of GHG in Brazil. In this work, amounts of CO2, CO, main hydrocarbon gases and PM2.5 emitted during deforestation fires, under real conditions directly in Brazilian Amazonia, were determined. A brief discussion of the relationship between the annual emission of CO2 equivalent (CO2,eq) and Paris Agreement was conducted. Experimental fires were carried out in Western Amazonia (Candeias do Jamari, Rio Branco and Cruzeiro do Sul) and results were compared with a previous fire carried out in Eastern Amazonia (Alta Floresta). The average total fresh biomass on the ground before burning and the total biomass consumption were estimated to be 591 ton ha−1 and 33%, respectively. CO2, CO, CH4, and non–methane hydrocarbon (NMHC) average emission factors, for the four sites, were 1568, 140, 8, and 3 g kg−1 of burned dry biomass, respectively. PM2.5 showed large variation among the sites (0.9–16 g kg−1). Emissions per hectare of forest were estimated as 216,696 kg of CO2, 18,979 kg of CO, 1,058 kg of CH4, and 496 kg of NMHC. The average annual emission of equivalent CO2 was estimated as 301 ± 53 Mt year−1 for the Brazilian Amazonia forest. From 2013, the estimated CO2,eq showed a trend to increase in Amazon region. The present study is an alert and provides important information that can be used in the development of the public policies to control emissions and deforestation in the Brazilian Amazonia.
Afficher plus [+] Moins [-]Microplastics in municipal mixed-waste organic outputs induce minimal short to long-term toxicity in key terrestrial biota
2019
(Danielle Peta),
Sustainable alternatives to landfill disposal for municipal mixed wastes represents a major challenge to governments and waste management industries. In the state of New South Wales (NSW) Australia, mechanical biological treatment (MBT) is being used to reduce the volume and pathogen content of organic matter isolated from municipal waste. The product of this treatment, a compost-like output (CLO) referred to as mixed waste organic output (MWOO), is being recycled and applied as a soil amendment. However, the presence of contaminants in MWOO including trace organics, trace metals and physical contaminants such as microplastic fragments has raised concerns about potential negative effects on soil health and agriculture following land application. Here, we used multiple lines of evidence to examine the effects of land application of MWOO containing microplastics in three soils to a variety of terrestrial biota. Treatments included unamended soil, MWOO-amended soil and MWOO-amended soil into which additional high-density polyethylene (HDPE), polyethylene terephthalate (PET), or polyvinyl chloride (PVC) microplastics were added. Tests were conducted in soil media that had been incubated for 0, 3 or 9 months. Addition of microplastics had no significant negative effect on wheat seedling emergence, wheat biomass production, earthworm growth, mortality or avoidance behaviour and nematode mortality or reproduction compared to controls. There was also little evidence the microplastics affected microbial community diversity, although measurements of microbial community structure were highly variable with no clear trends.
Afficher plus [+] Moins [-]Superior disinfection effect of Escherichia coli by hydrothermal synthesized TiO2-based composite photocatalyst under LED irradiation: Influence of environmental factors and disinfection mechanism
2019
Liu, Na | Zhu, Qi | Zhang, Nan | Zhang, Cheng | Kawazoe, Naoki | Chen, Guoping | Negishi, Nobuaki | Yang, Yingnan
The photocatalytic inactivation of Escherichia coli (E. coli) under light-emitting diode (LED) light irradiation was performed with P/Ag/Ag₂O/Ag₃PO₄/TiO₂ photocatalyst to investigate the photocatalytic bactericidal activity. Our work showed that this composite photocatalyst possessed remarkable bacterial disinfection ability and could completely inactivate 10⁸ cfu/mL of E. coli within just 40 min under the optimum catalyst loading of 0.5 g/L. The effects of different environmental factors, including light wavelength, light intensity, temperature, solution pH and inorganic ions, on the inactivation efficiency were evaluated. The results showed that bacteria inactivation by P/Ag/Ag₂O/Ag₃PO₄/TiO₂ was more favorable with blue colored LED irradiation, light intensity at 750 W/m², temperature in the range of 30–37 °C and pH values at natural or slightly alkaline condition. The existence of different inorganic ions under normal environmental level had no significant impact on the bactericidal performance. In addition, during the inactivation process, the morphology changes of E. coli cells were directly observed by scanning electron microscope (SEM) and further proved by the measurement of K⁺ leakage from the inactivated E. coli. The results demonstrated that the photocatalytic inactivation caused drastic damage on bacterial cells membrane. Furthermore, the mechanisms of photocatalytic bacterial inactivation were also systemically studied and the results confirmed that the excellent disinfection activity of P/Ag/Ag₂O/Ag₃PO₄/TiO₂ resulted from the major reactive species: h⁺ and ·O₂⁻ from photocatalytic process instead of the leakage of Ag⁺ (≤0.085 ± 0.005 mg/L) from photocatalyst. These results indicate that P/Ag/Ag₂O/Ag₃PO₄/TiO₂ photocatalyst has promising potential for real water sterilization application.
Afficher plus [+] Moins [-]The pollution level of the blaOXA-58 carbapenemase gene in coastal water and its host bacteria characteristics
2019
Xin, Rui | Zhang, Kai | Wu, Nan | Zhang, Ying | Niu, Zhiguang
This paper investigated 10 carbapenemase genes and selected the hosts of these genes in the estuary of Bohai Bay. The results showed that the OXA-58 producer accounted for a large percentage of carbapenem resistant bacteria in the sampling points, whereas the VIM, KPC, NDM, IMP, GES, OXA-23, OXA-24, OXA-48 and OXA-51 producers were not detected in the study. In addition, 9 bacterial genera with 100% identical blaOXA₋₅₈ sequences, including Pseudomonas, Rheinheimera, Stenotrophomonas, Shewanella, Raoultella, Vibrio, Pseudoalteromonas, Algoriphagus, Bowmanella and Thalassospira, were isolated from seawater. It is suggested that the host of blaOXA₋₅₈ gene were varied and many kinds of them could survive in the seawater. Moreover, we preformed the quantitative RT-PCR and the result shown the abundance of blaOXA₋₅₈ fluctuated between 2.8×10⁻⁶ copies/16S and 2.46×10⁻⁴ copies/16S, which was of the same order of magnitude as some common antibiotic resistance genes in environment. Furthermore, the variation trend of blaOXA₋₅₈ gene suggested that pollution discharge and horizontal gene transfer could contribute to the increase of the gene in coastal area.
Afficher plus [+] Moins [-]Persistence and migration of tetracycline, sulfonamide, fluoroquinolone, and macrolide antibiotics in streams using a simulated hydrodynamic system
2019
Liu, Xiaowei | Lv, Kai | Deng, Chengxun | Yu, Zhimin | Shi, Jianghong | Johnson, Andrew C.
The potential persistence and migration of 14 antibiotics comprising sulfonamides, fluoroquinolones, macrolides and tetracyclines were conducted using a 50-d recirculating flume study supported by batch attenuation experiments with spiked concentrations. The study demonstrated that photodegradation was the dominant attenuation process for these antibiotics in the water environment. The half-lives of 2–26 d were in order of sulfadiazine > sulfadimethoxine > sulfamerazine > sulfamethoxazole > sulfamethazine > sulfathiazole > ofloxacin > enrofloxacin > norfloxacin > ciprofloxacin > erythromycin > tetracycline > roxithromycin > oxytetracycline. These modest half-lives meant that the antibiotics were predicted to travel 30–400 km down a typical river before half the concentration would be lost. All antibiotics were detected on the surface sediment in the flume study. Under hyporheic exchange, some of them continually migrated into the deeper sediment and also the sediment pore water. All fluoroquinolones were detected in the sediments. The sulfonamides were detected in the pore water with relatively high concentrations and frequencies. Sulfadiazine, sulfamethazine and sulfathiazole in the upper layer pore water were found to be approaching equilibrium with the surface water. The high presence of sulfonamides in the pore water indicated that their high mobility and persistence potentially pose a risk to hyporheic zone.
Afficher plus [+] Moins [-]Personal exposure to PM2.5 constituents associated with gestational blood pressure and endothelial dysfunction
2019
Xia, Bin | Zhou, Yuhan | Zhu, Qingyang | Zhao, Yingya | Wang, Ying | Ge, Wenzhen | Yang, Qing | Zhao, Yan | Wang, Pengpeng | Si, Jingyi | Luo, Ranran | Li, Jialin | Shi, Huijing | Zhang, Yunhui
Ambient fine particulate matter (PM2.5) pollution has been implicated in the development of hypertensive disorders of pregnancy. However, evidence on the effects of PM2.5-derived chemical constituents on gestational blood pressure (BP) is limited, and the potential mechanisms underlying the association remain unclear. In this study, we repeated three consecutive 72-h personal air sampling and BP measurements in 215 pregnant women for 590 visits during pregnancy. Individual PM2.5 exposure level was assessed by gravimetric method and 28 PM2.5 chemical constituents were analyzed by ED-XRF method. Plasma biomarkers of endothelial function and inflammation were measured using multiplexed immunoassays. Robust multiple linear regression models were used to estimate the associations among personal PM2.5 exposure and chemical constituents, BP changes (compared with pre-pregnancy BP) and plasma biomarkers. Mediation analyses were performed to evaluate underlying potential pathways. Result showed that exposure to PM2.5 was significantly associated with increases in systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) in the early second trimester. Meanwhile, elevated concentration of lead (Pb) constituent in PM2.5 was significant associated with increases in DBP and MAP after adjusting for PM2.5 total mass. PM2.5 and Pb constituent also presented positive associations with plasma biomarkers of endothelial function (ET-1, E-selectin, ICAM-1) and inflammation (IL-1β, IL-6, TNFα) significantly. After multiple adjustment, elevated ET-1 and IL-6 were significantly correlated with increased gestational BP, and respectively mediated 1.24%–25.06% and 7.01%–10.69% of the increased BP due to PM2.5 and Pb constituent exposure. In conclusion, our results suggested that personal exposure to PM2.5 and Pb constituent were significantly associated with increased BP during pregnancy, and the early second trimester might be the sensitive window of PM2.5 exposure. The endothelial dysfunction and elevated inflammation partially mediated the effect of PM2.5 and Pb constituent on BP during pregnancy.
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