RESUMEN
The use of contaminated biomass and waste fuels is essential for waste management, waste to energy (WtE) and mitigating carbon emissions. The contamination of heavy metals and metalloids is specially concerned by environmental regulation and waste to energy processes. In this study, comparative characterisation is performed for three typical contaminated biomass and waste fuels. i.e. recycled woods, combustible municipal solid waste, and industrial and commercial wastes. The contamination characteristics are further analysed using statistical methods (e.g. significance, correlation, profile, and principal component analyses) to identify specific contamination features, relations among the contaminants and potential contamination sources. Contamination trend is estimated based on the continuously monitoring fuel qualities, the driving forces for regulating and reduction of the contaminations, and potential changes in major contamination sources. The comparative characterisation combined with statistical analyses provides a better way to understand the contamination mechanisms. The approach can also relate the fuel contamination with the contamination sources and their changes for trend estimation. Generally, the toxic heavy metals and metalloids are expected to be significantly reduced due to stricter regulations, but there is no general trend for the reduction of other metals and metalloids because of the complicated changes in contamination sources and waste recycling streams in the near future.
Asunto(s)
Contaminantes Ambientales/análisis , Metaloides/análisis , Metales Pesados/análisis , Biomasa , Monitoreo del Ambiente , Residuos Sólidos/análisis , Administración de Residuos , Madera/químicaRESUMEN
Cadmium (Cd) is one of the most toxic elements and can be accumulated in plants easily; meanwhile, eIF5A is a highly conserved protein in all eukaryotic organisms. The present work tried to investigate whether eIF5A is involved in Cd accumulation and sensitivity in Arabidopsis (Arabidopsis thaliana L.) by comparing the wild-type Columbia-0 (Col-0) with a knockdown mutant of AteIF5A-2, fbr12-3 under Cd stress conditions. The results showed that the mutant fbr12-3 accumulated more Cd in roots and shoots and had significantly lower chlorophyll content, shorter root length, and smaller biomass, suggesting that downregulation of AteIF5A-2 makes the mutant more Cd sensitive. Real-time polymerase chain reaction revealed that the expressions of metal transporters involved in Cd uptake and translocation including IRT1, ZIP1, AtNramp3, and AtHMA4 were significantly increased but the expressions of PCS1 and PCS2 related to Cd detoxification were decreased notably in fbr12-3 compared with Col-0. As a result, an increase in MDA and H2 O2 content but decrease in root trolox, glutathione and proline content under Cd stress was observed, indicating that a severer oxidative stress occurs in the mutant. All these results demonstrated for the first time that AteIF5A influences Cd sensitivity by affecting Cd uptake, accumulation, and detoxification in Arabidopsis.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Cadmio/metabolismo , Cadmio/toxicidad , Factores Eucarióticos de Iniciación/metabolismo , Arabidopsis/efectos de los fármacos , Proteínas de Arabidopsis/genética , Factores Eucarióticos de Iniciación/genética , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/genéticaRESUMEN
In order to study the mechanisms underlying the effects of TiO(2) nanoparticles on the brain, ICR mice were injected with nanoparticulate anatase TiO(2) (5 nm) of various doses into the abdominal cavity daily for 14 days. We then examined the coefficient of the brain, the brain pathological changes and oxidative stress-mediated responses, and the accumulation of nanoparticulate anatase TiO(2) and levels of neurochemicals in the brain. The results showed that high-dose nanoparticulate anatase TiO(2) could induce some neurons to turn into filamentous shapes and others into inflammatory cells. The concentration of nanoparticulate anatase TiO(2) in the brain was increased as increases in nanoparticulate anatase TiO(2) dosages used. The oxidative stress and injury of the brain occurred as nanoparticulate anatase TiO(2) appeared to trigger a cascade of reactions such as lipid peroxidation, the decreases of the total anti-oxidation capacity and activities of antioxidative enzymes, the excessive release of nitric oxide, the reduction of glutamic acid, and the downregulated level of acetylcholinesterase activities. We concluded that TiO(2) nanoparticles injected at the abdominal cavity could be translocated into the brain and in turn caused the brain injury.
Asunto(s)
Cavidad Abdominal , Encéfalo/efectos de los fármacos , Nanopartículas del Metal , Estrés Oxidativo , Titanio/farmacología , Animales , Antioxidantes/metabolismo , Peso Corporal , Encéfalo/enzimología , Encéfalo/metabolismo , Femenino , Peroxidación de Lípido , Ratones , Tamaño de los Órganos , Titanio/administración & dosificaciónRESUMEN
Nano-TiO2 and superoxide dismutase (SOD, EC 1.15.1.1) have been added to cosmetics and used to prevent injury of skin from UV-radiation, which might be related to the decrease of oxidative damage of skin. In previous studies we had proven that nano-anatase could increase the activity of SOD and decrease the oxidative damage in vivo. The mechanisms by which nano-anatase promoted SOD activity, however, are still not clearly understood. In the present work, nano-anatase in various concentrations was added to SOD from rat erythrocytes in vitro to gain insight into the mechanism of molecular interactions between nano-anatase and SOD by various spectral methods, suggesting that the reaction between SOD and nano-anatase was two-order, which meant that the SOD activity was greatly increased by low concentration of nano-anatase and inhibited by high concentration of nano-anatase. The spectroscopic assays suggested that the nano-anatase was determined to directly bind to SOD; the binding site of nano-anatase to SOD was 0.256 and the binding constants were 6.54 x 10(5) and 3.6 x 10(5)Lmol(-1); Ti was bound with three oxygen or nitrogen atoms and a sulfur atoms of amino acid residues at the Ti-O(N) and Ti-S bond lengths of 1.86 and 2.37 A, respectively, the binding nano-anatase entirely altered the secondary structure of SOD. It implied that the nano-anatase coordination created a new metal ion-active site form in SOD, thus leading to an enhancement in SOD activity.
Asunto(s)
Eritrocitos/enzimología , Depuradores de Radicales Libres/metabolismo , Nanoestructuras/química , Superóxido Dismutasa/metabolismo , Titanio/química , Animales , Depuradores de Radicales Libres/química , Humanos , Ratones , Estructura Secundaria de Proteína , Ratas , Superóxido Dismutasa/químicaRESUMEN
Lactate dehydrogenase (LDH, EC1.1.1.27), widely expressed in the heart, liver, and other tissues, plays an important role in glycolysis and glyconeogenesis. The activity of LDH is often altered upon inflammatory responses in animals. Nano-TiO(2) was shown to provoke various inflammatory responses both in rats and mice; however, the molecular mechanism by which TiO(2) exerts its toxicity has not been completely understood. In this report, we investigated the mechanisms of nano-anatase TiO(2) (5 nm) on LDH activity in vitro. Our results showed that LDH activity was greatly increased by low concentration of nano-anatase TiO(2), while it was decreased by high concentration of nano-anatase TiO(2). The spectroscopic assays revealed that the nano-anatase TiO(2) particles were directly bound to LDH with mole ratio of [nano-anatase TiO(2)] to [LDH] was 0.12, indicating that each Ti atom was coordinated with five oxygen/nitrogen atoms and a sulfur atoms of amino acid residues with the Ti-O(N) and Ti-S bond lengths of 1.79 and 2.41 A. We postulated that the bound nano-anatase TiO(2) altered the secondary structure of LDH, created a new metal ion-active site for LDH, and thereby enhanced LDH activity.
Asunto(s)
Colorantes/toxicidad , Corazón/efectos de los fármacos , L-Lactato Deshidrogenasa/biosíntesis , Miocardio/enzimología , Nanopartículas/toxicidad , Titanio/toxicidad , Animales , Activación Enzimática/efectos de los fármacos , L-Lactato Deshidrogenasa/química , L-Lactato Deshidrogenasa/efectos de los fármacos , RatasRESUMEN
Aiming at the development of a phosphorus removal technology for waste water, phosphate (PO(4)(3-)) retention behavior of bituminous and lignitous coal ashes was investigated using a batch reactor. Ash samples, including fresh and weathered fly and bottom ashes, were studied for their sorption isotherms and reversibility. Fly ashes had a much higher phosphate retention capacity (4000-30,000mgP/kg) than bottom ashes (15-600mgP/kg). Lignitous coal ashes were more capable of retaining phosphate than bituminous coal ashes. The retention process was largely irreversible, and the irreversibility increased with the increase in the retention capacity. Weathering enlarged the retention capacity of the bituminous bottom ash, but substantially lowered that of the fly ash, likely due to the difference in the weather-induced changes between the fly and bottom ashes. Sorption isotherms of fly ashes were found to be adequately represented by the Langmuir model while those of bottom ashes fitted better to the Freundlich model. Concentrations of Ca(2+) and PO(4)(3-) in the aqueous phase were measured at the end of sorption and desorption experiments, and were compared with solubilities of three calcium phosphate minerals. The aqueous solutions were saturated or super-saturated with respect to tricalcium phosphate (Ca(3)(PO(4))(2)) and hydroxyapatite (Ca(5)(PO(4))(3)OH), and slightly under-saturated with respect to amorphous calcium phosphate. It is concluded that precipitation of calcium phosphate is the predominant mechanism for phosphate retention by coal ash under the conditions studied. There is a strong and positive correlation between alkalinity and phosphate sorption capacity. Consequently, acid neutralization capacity (ANC) can be used as an indicator of phosphate sorption capacity of coal ashes.