Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 21
Filtrar
1.
Appl Environ Microbiol ; 89(12): e0166223, 2023 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-38047646

RESUMO

IMPORTANCE: Antibiotics can induce dose-dependent hormetic effects on bacterial cell proliferation, i.e., low-dose stimulation and high-dose inhibition. However, the underlying molecular basis has yet to be clarified. Here, we showed that sulfonamides play dual roles as a weapon and signal against Comamonas testosteroni that can modulate cell physiology and phenotype. Subsequently, through investigating the hormesis mechanism, we proposed a comprehensive regulatory pathway for the hormetic effects of Comamonas testosteroni low-level sulfonamides and determined the generality of the observed regulatory model in the Comamonadaceae family. Considering the prevalence of Comamonadaceae in human guts and environmental ecosystems, we provide critical insights into the health and ecological effects of antibiotics.


Assuntos
Hormese , Sulfonamidas , Humanos , Sulfonamidas/farmacologia , Ecossistema , Percepção de Quorum , Sulfanilamida/farmacologia , Antibacterianos/farmacologia
2.
Environ Pollut ; 316(Pt 2): 120659, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36379289

RESUMO

Dam construction has far-reaching impacts on pollutant accumulation and the pollutant-induced quality of aquatic environments. Nonetheless, its large-scale effects on pollutant distribution in sediments, which greatly contribute to the environmental impacts of coexisting pollutants, remain poorly understood. We collected sediments from the Yangtze River during the dry and normal seasons (with 'normal' defined in terms of precipitation level), and examined how dam construction alters the spatial trajectories of both inorganic and organic pollutants in the sediments. Sediment composition exhibited linear variation from the upper to the lower reaches, with clay and silt particles dominating the sediment in the Three Gorges Reservoir and sand particles dominating in the middle-lower reaches. Accordingly, upstream of the Three Gorges Dam (TGD), sedimentary carbon, nitrogen, phosphorus, heavy metal, polycyclic aromatic hydrocarbons (PAHs), and oxygenated PAHs (OPAHs) contents increased toward the TGD owing to its regulation of the spatial variation in sediment particle size. The TGD caused upstream sedimentary accumulation of pollutants to be higher nearer to the TGD than in the upper reaches by 17%-129% for carbon, nitrogen, and phosphorus, 7%-51% for heavy metals, 30% for PAHs, and 140% for OPAHs. Pollutant content was sharply lower below the TGD, by 0.58-11.15 times for carbon, nitrogen, and phosphorus, 0.1-2.6 times for heavy metals, 1.7 times for PAHs, and 5.6 times for OPAHs. Upstream of the TGD, levels of NH4+-N, the main form of N in the interstitial water of the Yangtze River, increased lineary toward the TGD, whereas those of NO3--N and NO2--N decreased. Sedimentary organic matter source contributions were consistent along the Yangtze River, being on an average 46% for C3 plants and 28% for soil organic substances, further confirming the dam's regulatory effect on pollutants. These findings provide a foundation for future assessments of the environmental impact of dam-induced river fragmentation and hydrological alterations, and for developing advanced watershed pollutant management strategies.


Assuntos
Poluentes Ambientais , Metais Pesados , Hidrocarbonetos Policíclicos Aromáticos , Poluentes Químicos da Água , Rios , Monitoramento Ambiental , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , Fósforo , Nitrogênio , Carbono , China , Sedimentos Geológicos
3.
J Environ Sci (China) ; 103: 246-254, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33743906

RESUMO

Water transfer is becoming a popular method for solving the problems of water quality deterioration and water level drawdown in lakes. However, the principle of choosing water sources for water transfer projects has mainly been based on the effects on water quality, which neglects the influence in the variation of phytoplankton community and the risk of algal blooms. In this study, algal growth potential (AGP) test was applied to predict changes in the phytoplankton community caused by water transfer projects. The feasibility of proposed water transfer sources (Baqing River and Jinsha River) was assessed through the changes in both water quality and phytoplankton community in Chenghai Lake, Southwest China. The results showed that the concentration of total nitrogen (TN) and total phosphorus (TP) in Chenghai Lake could be decreased to 0.52 mg/L and 0.02 mg/L respectively with the simulated water transfer source of Jinsha River. The algal cell density could be reduced by 60%, and the phytoplankton community would become relatively stable with the Jinsha River water transfer project, and the dominant species of Anabaena cylindrica evolved into Anabaenopsis arnoldii due to the species competition. However, the risk of algal blooms would be increased after the Baqing River water transfer project even with the improved water quality. Algae gained faster proliferation with the same dominant species in water transfer source. Therefore, water transfer projects should be assessed from not only the variation of water quality but also the risk of algal blooms.


Assuntos
Monitoramento Ambiental , Água , China , Cianobactérias , Eutrofização , Lagos , Nitrogênio/análise , Fósforo/análise , Fitoplâncton , Qualidade da Água
4.
Environ Sci Technol ; 53(15): 9073-9080, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31241325

RESUMO

Lanthanum (La)-based materials have been recognized as promising adsorbents for aqueous phosphate removal. The incorporation of base metals into La (oxy)hydroxides represents an effective strategy to improve adsorption performance. Understanding how base metals affect phosphate adsorption is challenging but essential for the development of effective materials for phosphorus control. Herein, we demonstrated a high-performance LaFe (oxy)hydroxide and studied its mechanisms on phosphate adsorption. The P K edge X-ray absorption near edge structure (XANES) analysis showed that PO43- was preferentially bonded with La, and the lattice oxygen in LaFe (oxy)hydroxide was demonstrated to be the active site. The O K edge XANES suggested that Fe optimized the electron structure of La, and Fe/La metal orbital hybridization resulted in the shift of oxygen p character to unoccupied states, facilitating phosphate adsorption. Furthermore, surface analysis showed that the pore size and volume were increased due to the introduction of Fe, which enabled efficient utilization of the active sites and fast adsorption kinetics. The dual effects of Fe in LaFe (oxy)hydroxide greatly enhance the effectiveness of La and represent a new strategy for the development of future phosphorus-control materials.


Assuntos
Oxigênio , Fósforo , Adsorção , Hidróxidos , Fosfatos
5.
J Environ Sci (China) ; 78: 267-275, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30665645

RESUMO

Microplastics have caused great concern worldwide recently due to their ubiquitous presence within the marine environment. Up to now, most attention has been paid to their sources, distributions, measurement methods, and especially their eco-toxicological effects. With microplastics being increasingly detected in freshwater, it is urgently necessary to evaluate their behaviors during coagulation and ultrafiltration (UF) processes. Herein, the removal behavior of polyethylene (PE), which is easily suspended in water and is the main component of microplastics, was investigated with commonly used Fe-based salts. Results showed that although higher removal efficiency was induced for smaller PE particles, low PE removal efficiency (below 15%) was observed using the traditional coagulation process, and was little influenced by water characteristics. In comparison to solution pH, PAM addition played a more important role in increasing the removal efficiency, especially anionic PAM at high dosage (with efficiency up to 90.9%). The main reason was ascribed to the dense floc formation and high adsorption ability because of the positively charged Fe-based flocs under neutral conditions. For ultrafiltration, although PE particles could be completely rejected, slight membrane fouling was caused owing to their large particle size. The membrane flux decreased after coagulation; however, the membrane fouling was less severe than that induced by flocs alone due to the heterogeneous nature of the cake layer caused by PE, even at high dosages of Fe-based salts. Based on the behavior exhibited during coagulation and ultrafiltration, we believe these findings will have potential application in drinking water treatment.


Assuntos
Água Potável/química , Plásticos/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Floculação , Ferro/química , Membranas Artificiais , Plásticos/análise , Ultrafiltração/métodos , Poluentes Químicos da Água/análise
6.
Chemosphere ; 197: 793-802, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29407843

RESUMO

Severe ultrafiltration (UF) membrane fouling is always induced by humic acid (HA). However, little attention has been paid to the influence of inorganic salts, and even the studies related have been limited to only a single kind of salt. In addition, the concentration of the inorganic salts reported in previous studies is much high. Herein, the effect of HA on UF membrane performance was investigated in the presence of typical inorganic salts, with concentrations similar to those in natural waters or actually used in most current water plants. The results showed that membrane performance was influenced little by monovalent inorganic salts (NaCl and KCl), while divalent inorganic salts (CaCl2 and MgCl2) could exacerbate the membrane fouling. For trivalent inorganic salts (AlCl3·6H2O and FeCl3·6H2O), floc adsorption was the dominant HA removing mechanism, and AlCl3·6H2O behaved better than FeCl3·6H2O. Relating to the floc properties, severe membrane fouling occurred with low dosage, while it was mitigated with high dosage. Compared with the trivalent inorganic salts, more severe membrane fouling was caused by divalent inorganic salts. Additionally, little synergistic or inhibitory effect occurred with mixtures of divalent inorganic salts and trivalent inorganic salts. Furthermore, analysis with the classical fouling models showed that cake filtration was the main fouling mechanism with/without inorganic salts. Based on the findings, we believe these different HA behaviors exhibited during coagulation process with inorganic salts will have a large potential application in UF membrane fouling alleviation in water treatment.


Assuntos
Substâncias Húmicas/análise , Membranas Artificiais , Ultrafiltração/métodos , Purificação da Água/métodos , Adsorção , Sulfatos/farmacologia
7.
Appl Microbiol Biotechnol ; 101(19): 7293-7302, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28852824

RESUMO

Traditional wastewater treatments based on activated sludge often encounter the problems of bulking and foaming, as well as malodor. To solve these problems, new treatment technologies have emerged in recent decades, including the ecological wastewater treatment process, which introduces selected local plants into the treatment system. With a focus on the underlying mechanisms of the ecological treatment process, we explored the microbial community biomass, composition, and function in the treatment system to understand the microbial growth in this system and its role in pollutant removal. Flow cytometry analysis revealed that ecological treatment significantly decreased influent bacterial quantity, with around 80% removal. 16S rRNA gene sequencing showed that the ecological treatment also altered the bacterial community structure of the wastewater, leading to a significant change in Comamonadaceae in the effluent. In the internal ecological system, because most of microbes aggregate in the plant rhizosphere and the sludge under plant roots, we selected two plant species (Nerium oleander and Arundo donax) to study the characteristics of rhizosphere and sludge microbes. Metagenomic results showed that the microbial community composition and function differed between the two species, and the microbial communities of A. donax were more sensitive to seasonal effects. Combined with their greater biomass and abundance of metabolic genes, microbes associated with N. oleander showed a greater contribution to pollutant removal. Further, the biodegradation pathways of some micropollutants, e.g., atrazine, were estimated.


Assuntos
Consórcios Microbianos , Eliminação de Resíduos Líquidos , Águas Residuárias/microbiologia , Purificação da Água , Biodegradação Ambiental , Biomassa , Comamonadaceae/genética , Comamonadaceae/isolamento & purificação , Metagenômica , Nerium/microbiologia , Poaceae/microbiologia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
8.
Huan Jing Ke Xue ; 37(4): 1451-9, 2016 Apr 15.
Artigo em Chinês | MEDLINE | ID: mdl-27548968

RESUMO

Substituted polycyclic aromatic hydrocarbons (SPAHs) can be emitted to the environment not only through the incomplete combustion, but also through the transformation from parent polycyclic aromatic hydrocarbons (PAHs) by photo chemical and biological processes. The toxicities of some SPAHs are higher than their corresponding PAHs. Samples were collected from the wastewater treatment plants in Beijing. Three types of SPAHs, including oxy-PAHs (OPAHs), methyl-PAHs (MPAHs) and nitro-PAHs (NPAHs), as well as 16 PAHs were analyzed, in order to study the occurrence and behavior of these compounds during the wastewater biological treatment process. MPAHs, OPAHs and PAHs were detected in the influent and effluent, but no NPAHs. The concentrations of PAHs in the influent in both the aquatic and particulate phases ranged from 1.94 to 4.34 µg · L⁻¹, and SPAHs from 1.16 to 2.20 µg · L⁻¹. The concentrations of PAHs in the effluent were between 0.77 and 0.98 µg · L⁻¹, and SPAHs from 0.39 to 0.45 µg · L⁻¹. The concentrations of the MPAHs were lower than their corresponding PAHs, while OPAHs were higher. The removal efficiencies of all the compounds ranged from 53% to 83%. PAHs and SPAHs were mainly removed by adsorption and biodegradation during the activated sludge treatment processes. Some OPAHs could be transformed from PAHs, and could be accumulated. The PAHs were mainly originated from incomplete combustion of wood and coal, and some from combustion of petroleum, while only a little from the discharge of petroleum. The concentrations of PAHs and SPAHs in the effluent were higher in autumn than summer and winter. Most of the SPAHs and PAHs were discharged to the agriculture area through the river-water irrigation, which might pose potential risk to the humans. As a result, it is necessary to upgrade the wastewater treatment process to improve the removal efficiency of PAHs and SPAHs.


Assuntos
Monitoramento Ambiental , Hidrocarbonetos Policíclicos Aromáticos/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise , Adsorção , Pequim , Carvão Mineral , Petróleo , Rios , Estações do Ano , Esgotos
9.
Phys Chem Chem Phys ; 18(14): 9437-45, 2016 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-26980402

RESUMO

FeOOH, a frequently used adsorbent, has been widely applied in purifying aqueous heavy metals, and its performance can be greatly improved by enlarging the number of surface active sites. To this end, we fabricated FeOOH hollow microboxes constructed from numerous 2D nanosheets via a template-engaged reaction between Prussian blue (PB) and NaOH solution. With combined observations from X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), we confirmed that the hollow microboxes corroded from PB were composed of ample frizzy FeOOH nanosheets, which ensured extensive exposure of the surface active sites. Moreover, the FeOOH microboxes were utilized as an adsorbent in the removal of heavy metals (As(III), As(V) and Se(IV)) from water and the maximum adsorption capacities were reached up to 192.19 mg g(-1), 250.0 mg g(-1) and 169.9 mg g(-1) at pH = 7.0, 4.0 and 5.0, respectively. The superior adsorptive performance of the FeOOH microboxes was derived from their large content of reactive exposed hydroxyl groups, which was unambiguously confirmed by X-ray adsorption fine structure spectroscopy (XAFS), as well as by surface site density analysis.


Assuntos
Compostos Férricos/química , Metais Pesados/isolamento & purificação , Nanoestruturas/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Arsênio/isolamento & purificação , Nanoestruturas/ultraestrutura , Selênio/isolamento & purificação
10.
Environ Sci Technol ; 49(3): 1690-7, 2015 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-25564945

RESUMO

Fe2O3 and/or Al2O3 were supported on mesoporous SBA-15 by wet impregnation and calcinations with AlCl3 and FeCl3 as the metal precursor and were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectra (FTIR) of adsorbed pyridine. Fe2O3/Al2O3@SBA-15 was found to be highly effective for the mineralization of ibuprofen aqueous solution with ozone. The characterization studies showed that Al-O-Si was formed by the substitution of Al(3+) for the hydrogen of surface Si-OH groups, not only resulting in high dispersion of Al2O3 and Fe2O3 on SBA-15, but also inducing the greatest amount of surface Lewis acid sites. By studies of in situ attenuated total reflection FTIR (ATR-FTIR), in situ Raman, and electron spin resonance (ESR) spectra, the chemisorbed ozone was decomposed into surface atomic oxygen species at the Lewis acid sites of Al(3+) while it was converted into surface adsorbed (•)OHads and O2(•-) radicals at the Lewis acid sites of Fe(3+). The combination of both Lewis acid sites of iron and aluminum onto Fe2O3/Al2O3@SBA-15 enhanced the formation of (•)OHads and O2(•-) radicals, leading to highest reactivity. Mechanisms of catalytic ozonation were proposed for the tested catalysts on the basis of all the experimental information.


Assuntos
Ibuprofeno/química , Ozônio/química , Adsorção , Óxido de Alumínio/química , Catálise , Espectroscopia de Ressonância de Spin Eletrônica , Compostos Férricos/química , Oxigênio/química , Espectroscopia Fotoeletrônica , Dióxido de Silício/química , Espectroscopia de Infravermelho com Transformada de Fourier , Suspensões , Água/química , Difração de Raios X
11.
Bioresour Technol ; 140: 312-8, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23711939

RESUMO

Three activated sludge processes (ASPs) were modeled and driven by dissolved complex organics (F-ASP), propionic acid (P-ASP), and acetic acid (A-ASP), and various parameters were subsequently estimated. The energy depletion for carbon removal was 0.146, 0.120, and 0.119 kWh/m(3) of treated wastewater for F-ASP, P-ASP, and A-ASP, respectively, suggesting that acetic acid can forward energy conservation. The ratio of substrate storage to oxidation in F-ASP, P-ASP, and A-ASP was 0, 0.25, and 0.52, respectively, further demonstrating that substrate eliminations from P-ASP and A-ASP were both dominated by substrate storage for polymer production, not by total oxidation; thus, they exhibited lower energy-consuming levels than F-ASP. Quantification of bioenergy production and nutrient acquisition from the excess sludge of the three ASPs were conducted subsequently, and A-ASP was found to facilitate phosphorus capture.


Assuntos
Carbono/química , Modelos Teóricos , Esgotos/química , Esgotos/microbiologia , Técnicas de Cultura Celular por Lotes , Análise da Demanda Biológica de Oxigênio , Eletricidade , Cinética , Nitrogênio/isolamento & purificação , Oxirredução , Fosfatos/isolamento & purificação , Fósforo/isolamento & purificação , Solubilidade , Termodinâmica , Volatilização
12.
Environ Sci Technol ; 44(18): 7058-62, 2010 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-20734989

RESUMO

The plasmon-induced photocatalytic inactivation of enteric pathogenic microorganisms in water using Ag-AgI/Al(2)O(3) under visible-light irradiation was investigated. The catalyst was found to be highly effective at killing Shigella dysenteriae (S. dysenteriae), Escherichia coli (E. coli), and human rotavirus type 2 Wa (HRV-Wa). Its bactericidal efficiency was significantly enhanced by HCO(3)(-) and SO(4)(2-) ions, which are common in water, while phosphate had a slightly positive effect on the disinfection. Meanwhile, more inactivation of E. coli was observed at neutral and alkaline pH than at acid pH in Ag-AgI/Al(2)O(3) suspension. Furthermore, the effects of inorganic anions and pH on the transfer of plasmon-induced charges were investigated using cyclic voltammetry analyses. Two electron-transfer processes occurred, from bacteria to Ag nanoparticles (NPs) and from inorganic anions to Ag NPs to form anionic radicals. These inorganic anions including OH(-) in water not only enhanced electron transfer from plasmon-excited Ag NPs to AgI and from E. coli to Ag NPs, but their anionic radicals also increased bactericidal efficiency due to their absorbability by cells. The plasmon-induced electron holes (h(+)) on Ag NPs, O(2)(•-), and anionic radicals were involved in the reaction. The enhanced electron transfer is more crucial than the electrostatic force interaction of bacteria and catalyst for the plasmon-induced inactivation of bacteria using Ag-AgI/Al(2)O(3).


Assuntos
Óxido de Alumínio/farmacologia , Enterobacteriaceae/efeitos dos fármacos , Iodetos/farmacologia , Luz , Viabilidade Microbiana/efeitos da radiação , Compostos de Prata/farmacologia , Prata/farmacologia , Inativação de Vírus/efeitos da radiação , Catálise/efeitos dos fármacos , Catálise/efeitos da radiação , Desinfecção , Enterobacteriaceae/patogenicidade , Enterobacteriaceae/efeitos da radiação , Escherichia coli/efeitos dos fármacos , Escherichia coli/efeitos da radiação , Humanos , Concentração de Íons de Hidrogênio/efeitos dos fármacos , Concentração de Íons de Hidrogênio/efeitos da radiação , Íons , Cinética , Viabilidade Microbiana/efeitos dos fármacos , Rotavirus/efeitos dos fármacos , Rotavirus/efeitos da radiação , Shigella/efeitos dos fármacos , Shigella/efeitos da radiação , Fatores de Tempo , Inativação de Vírus/efeitos dos fármacos
13.
Environ Sci Technol ; 43(7): 2525-9, 2009 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-19452911

RESUMO

Catalytic ozonation of five pharmaceutical compounds (PhACs)-phenazone, ibuprofen, diphenhydramine, phenytoin, and diclofenac sodium in alumina-supported manganese oxide (MnOx) suspension was carried out with a semicontinuous laboratory reactor. MnOx supported by mesoporous alumina (MnOx/MA) was highly effective in mineralizing the PhACs in aqueous solution. Fourier transform infrared (FTIR) spectroscopy and in situ attenuated total reflection FTIR (ATR-FTIR) spectroscopy were used to examine the interaction of ozone with different catalysts undervarious conditions. The crucial active sites, surface oxide species at 1380 cm(-1), were formed by the interaction of ozone with Lewis acid sites on the alumina surface. New surface hydroxyl groups at 2915 and 2845 cm(-1) were produced by the interaction of the catalyst and ozone in aqueous suspension and became active sites in the presence of MnOx. The introduction of MnOx enhanced the formation and activation of surface hydroxyl groups, causing higher catalytic reactivity. On the basis of these findings, a reaction mechanism is proposed for the catalytic ozonation of PhACs in MnOx/MA suspension.


Assuntos
Óxido de Alumínio/química , Compostos de Manganês/química , Óxidos/química , Ozônio/química , Preparações Farmacêuticas/química , Catálise , Espectroscopia de Infravermelho com Transformada de Fourier
14.
Toxicon ; 51(4): 649-58, 2008 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-18221764

RESUMO

Effects of nitrogen-limitation and phosphorus-limitation on microcystin (MC) content and energy charge (EC) of the Microcystis aeruginosa were investigated in batch cultures and semi-continuous cultures. In batch cultures, nitrogen-limitation retarded the MC synthesis and phosphorus-limitation had little effects on MC production. The EC remained constant in nitrogen-limited cultures, while it decreased largely when phosphorus was extinct in phosphorus-limited culture. In the semi-continuous cultures, MC production in nitrogen- and phosphorus-limited cultures increased with the increase of dilution rate; however, MC content in phosphorus-limited cultures was more than that in nitrogen-limited cultures. The EC in nitrogen-limited cultures remained constant and in phosphorus-limited cultures increased with the increase of dilution rate. In phosphorus-limited semi-continuous cultures, a direct relationship between EC and MC content was demonstrated. No correlation was observed in nitrogen-limited semi-continuous cultures. Based on the above analysis, a mechanism of nitrogen and phosphorus effect on the MC synthesis was suggested, that the MC synthesis was determined by the combination of necessary enzymes and precursors and EC.


Assuntos
Microcystis/metabolismo , Nitrogênio/metabolismo , Fósforo/metabolismo , Técnicas Bacteriológicas , Metabolismo Energético , Toxinas Marinhas , Microcistinas/metabolismo
15.
J Hazard Mater ; 153(1-2): 470-7, 2008 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-17919815

RESUMO

The present study investigated the cyanobacteria and one family of their toxins-microcystins (MCs) in Guanting Reservoir of Beijing, China. The dominant species in the cyanobacteria found in August and September of 2006 was Microcystis, which accounted 99% of total algal cells. The specific species of the Microcystis in the cyanobacteria included Microcystis ichthyobalbe, Microcystis novacekii, Microcystis botrys and Microcystis aeruginosa which had different ratios in different sites. The qualitative analysis by HPLC showed that two microcystins were contained in cyanobacteria and one microcystin was in water of the reservoir. The major microcystins were microcystin-RR (MC-RR) and microcystin-LR (MC-LR), but only MC-LR was detected in water. The quantitative analysis by HPLC indicated that the maximum concentrations of MC-RR and MC-LR contained in cyanobacteria were 0.74 and 0.41 mg/g dry weight, respectively. The maximum microcystin concentration in water was 1.15 microg/L and others were below 1 microg/L.


Assuntos
Toxinas Bacterianas/análise , Microcistinas/análise , Microcystis/isolamento & purificação , Poluentes da Água/análise , Abastecimento de Água/análise , China , Contagem de Colônia Microbiana , Monitoramento Ambiental , Toxinas Marinhas , Microcystis/química , Microcystis/classificação , Nitrogênio/análise , Fósforo/análise , Microbiologia da Água
16.
Langmuir ; 23(22): 11197-9, 2007 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-17902710

RESUMO

The bactericidal process of Ag/Al2O3 to Escherichia coli has been investigated to clarify the bactericidal mechanism. In SEM images, the configuration of E. coli cells contacting with the catalyst surface was quite different from that contacting with AgNO3 solution, which indicated that the Ag+ eluted from the catalyst did not play an important role in the bactericidal process. The bactericidal experiments strongly confirmed the contribution of multiform reactive oxygen species (ROS) (super oxide dismutase (SOD) and catalase as the scavengers for O2*- and H2O2, respectively) to bactericidal effect on the catalyst surface. Furthermore, the surface modification of Ag/Al2O3 by ultraviolet and formaldehyde influenced the bactericidal effect obviously, which not only confirmed the bactericidal mechanism of catalytic oxidation but also provided evidence for the synergistic effect between Ag and Al2O3 on the catalyst surface.


Assuntos
Óxido de Alumínio/farmacologia , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Prata/farmacologia , Adsorção , Catalase/farmacologia , Escherichia coli/metabolismo , Escherichia coli/ultraestrutura , Formaldeído , Sequestradores de Radicais Livres/farmacologia , Microscopia Eletrônica de Varredura , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/farmacologia , Propriedades de Superfície , Raios Ultravioleta
17.
Chemosphere ; 68(11): 2153-60, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17363030

RESUMO

Little is known about how the growth of trihalomethanes (THMs) in drinking water is affected in copper pipe. The formation of THMs and chlorine consumption in copper pipe under stagnant flow conditions were investigated. Experiments for the same water held in glass bottles were performed for comparison. Results showed that although THMs levels firstly increased in the presence of chlorine in copper pipe, faster decay of chlorine as compared to the glass bottle affected the rate of THMs formation. The analysis of water phase was supplemented by surface analysis of corrosion scales using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDX). The results showed the scales on the pipe surface mainly consisted of Cu(2)O, CuO and Cu(OH)(2) or CuCO(3). Designed experiments confirmed that the fast depletion of chlorine in copper pipe was mainly due to effect of Cu(2)O, CuO in corrosion scales on copper pipe. Although copper(II) and copper oxides showed effect on THMs formation, the rapid consumption of chlorine due to copper oxide made THM levels lower than that in glass bottles after 4h. The transformations of CF, DCBM and CDBM to BF were accelerated in the presence of copper(II), cupric oxide and cuprous oxide. The effect of pH on THMs formation was influenced by effect of pH on corrosion of copper pipe. When pH was below 7, THMs levels in copper pipe was higher as compared to glass bottle, but lower when pH was above 7.


Assuntos
Cobre/química , Trialometanos/química , Cloro/química , Microscopia Eletrônica de Varredura , Água/química , Poluentes Químicos da Água
18.
J Inorg Biochem ; 101(5): 817-23, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17350102

RESUMO

Bactericidal action of Al(2)O(3), Ag/Al(2)O(3) and AgCl/Al(2)O(3) on pure culture of Escherichia coli K 12 was studied. Ag/Al(2)O(3) and AgCl/Al(2)O(3) demonstrated a stronger bactericidal activity than Al(2)O(3). The colony-forming ability of E. coli was completely lost in 0.5 min on both of Ag/Al(2)O(3) and AgCl/Al(2)O(3) at room temperature in air. The configuration of the bacteria on the catalyst surface was observed using scanning electron microscopy (SEM). Reactive oxygen species (ROS) play an important role in the expression of the bactericidal activity on the surface of catalysts by assay with O(2)/N(2) bubbling and scavenger for ROS. Furthermore, the formation of CO(2) as an oxidation product could be detected by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and be deduced by total carbon analysis. These results strongly support that the bactericidal process on the surface of Ag/Al(2)O(3) and AgCl/Al(2)O(3) was caused by the catalytic oxidation.


Assuntos
Escherichia coli K12/efeitos dos fármacos , Esterilização/métodos , Óxido de Alumínio , Catálise , Contagem de Colônia Microbiana , Escherichia coli K12/crescimento & desenvolvimento , Escherichia coli K12/ultraestrutura , Microscopia Eletrônica de Varredura , Espécies Reativas de Oxigênio , Prata , Espectroscopia de Infravermelho com Transformada de Fourier , Superóxido Dismutase
19.
Artigo em Inglês | MEDLINE | ID: mdl-17018420

RESUMO

A novel dual-function chemical reagent was successfully prepared by electrolysis process. With high content of Al13 species and active chlorine, the electrochemically prepared polyaluminum chlorine (E-PACl) as the dual-function chemical reagent presented the integrated properties of coagulation and disinfection in water treatment. The results obtained from jar tests in municipal wastewater and hydrolyzed Al (III) speciation distribution characterization confirmed that the Al13 species was the most effective polymeric Al species in PACl responsible for coagulation. The solid-state 27Al NMR spectra for precipitates revealed that the precipitates structure formed from Al coagulants with various pre-hydrolysis degrees were significantly different, and proved that the preformed Al13 polymer is quite stable during the coagulation process. E-PACl performed well on both particulate and organic matter removals in municipal wastewater treatment. The higher the degree of pre-hydrolysis, the lower the efficiency of the coagulant removed phosphorus from water. The active chlorine in E-PACl was an effective disinfectant to inactivate fecal coliforms. When dosed 24 mg Al/L E-PACl, effective coagulation and disinfection in municipal wastewater could be achieved simultaneously. E-PACl may have a great potential to domestic use and small treatment plants for municipal wastewater reuse.


Assuntos
Hidróxido de Alumínio/síntese química , Desinfetantes/síntese química , Eletrólise , Esgotos/microbiologia , Microbiologia da Água , Purificação da Água , Hidróxido de Alumínio/química , Hidróxido de Alumínio/farmacologia , China , Cidades , Desinfetantes/química , Desinfetantes/farmacologia , Enterobacteriaceae/efeitos dos fármacos , Fezes/microbiologia , Floculação , Nefelometria e Turbidimetria , Fósforo/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos
20.
Huan Jing Ke Xue ; 25(1): 30-4, 2004 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-15330416

RESUMO

Sb-doped SnO2/Ti anode was prepared in our lab with thermal decomposition method, and in the same time, the effect of heat treatment on the properties of the electrode also was studied. Scanning electron microscopy (SEM) was used to study the surface characterization of the electrodes. X-ray photoelectro-spectroscopy (XPS) measurements were carried out to study the chemical state of elements, Sn and Sb. The potentiodynamic polarization behaviors of the two anodes in different solutions were performed. Galvanostatic electrolyses were carried out at 5 mA/cm2 to study the electrocatalytic activity of the two anodes in removing organic pollutant. SEM showed that the electrodes had the same well-known cracked-mud structure, while the electrode annealed in O2 [SnO2/Ti(O2)] had more larger surface area than the electrode annealed in the air [SnO2/Ti(air)]. XPS measurements showed that the binding energies of both Sn3d(5/2) and Sb3d(5/2) of SnO2/Ti(O2) were 0.15 eV smaller than what of the SnO2/Ti(air) film. Both of the electrochemical measurements and electrolyses results confirmed that SnO2/Ti(O2) was more active in the degradation of organic pollutant. The galvanostatic electrolyses lasted until the solutions were decoloured throughly, 76.3% of total organic carbon (TOC) was removed with SnO2/Ti(O2), compared with 63.3% of SnO2/Ti(air). The similar exponential rules were driven for the variations of residual TOC concentration with two anodes.


Assuntos
Benzoquinonas/química , Temperatura Alta , Compostos de Estanho/química , Titânio/química , Purificação da Água/métodos , Catálise , Eletroquímica , Eletrodos , Oxirredução , Fotoquímica , Poluentes Químicos da Água/isolamento & purificação , Poluentes Químicos da Água/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA