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Resultados 2781-2790 de 4,033
Use of sugarcane filter cake and nitrogen, phosphorus and potassium fertilization in the process of bioremediation of soil contaminated with diesel
2016
Tellechea, Fernando Reynel Fundora | Martins, Marco Antonio | da Silva, Alexsandro Araujo | da Gama-Rodrigues, Emanuela Forestieri | Martins, Meire Lelis Leal
This study evaluated the use of sugarcane filter cake and nitrogen, phosphorus and potassium (NPK) fertilization in the bioremediation of a soil contaminated with diesel fuel using a completely randomized design. Five treatments (uncontaminated soil, T1; soil contaminated with diesel, T2; soil contaminated with diesel and treated with 15 % (wt) filter cake, T3; soil contaminated with diesel and treated with NPK fertilizer, T4; and soil contaminated with diesel and treated with 15 % (wt) filter cake and NPK fertilizer, T5) and four evaluation periods (1, 60, 120, and 180 days after the beginning of the experiment) were used according to a 4 × 5 factorial design to analyze CO₂ release. The variables total organic carbon (TOC) and total petroleum hydrocarbons (TPH) remaining in the soil were analyzed using a 5 × 2 factorial design, with the same treatments described above and two evaluation periods (1 and 180 days after the beginning of the experiment). In T3 and T5, CO₂ release was significantly higher, compared with the other treatments. Significant TPH removal was observed on day 180, when percent removal values were 61.9, 70.1, 68.2, and 75.9 in treatments T2, T3, T4, and T5, respectively, compared with the initial value (T1).
Mostrar más [+] Menos [-]Mediterranean aerosol typing by integrating three-wavelength lidar and sun photometer measurements
2016
Perrone, M. R. | Burlizzi, P.
Backscatter lidar measurements at 355, 532, and 1064 nm combined with aerosol optical thicknesses (AOTs) from sun photometer measurements collocated in space and time were used to retrieve the vertical profiles of intensive and extensive aerosol parameters. Then, the vertical profiles of the Ångström coefficients for different wavelength pairs (Å(λ₁, λ₂, z)), the color ratio (CR(z)), the fine mode fraction (η(z)) at 532 nm, and the fine modal radius (R f (z)), which represent aerosol characteristic properties independent from the aerosol load, were used for typing the aerosol over the Central Mediterranean. The ability of the Ångström coefficients to identify the main aerosol types affecting the Central Mediterranean with the support of the backward trajectory analysis was first demonstrated. Three main aerosol types, which were designed as continental-polluted (CP), marine-polluted (MP), and desert-polluted (DP), were identified. We found that both the variability range and the vertical profile structure of the tested aerosol intensive parameters varied with the aerosol type. The variability range and the altitude dependence of the aerosol extinction coefficients at 355, 532, and 1064 nm, respectively, also varied with the identified aerosol types even if they are extensive aerosol parameters. DP, MP, and CP aerosols were characterized by the Å(532, 1064 nm) mean values ± 1 standard deviation equal to 0.5 ± 0.2, 1.1 ± 0.2, 1.6 ± 0.2, respectively. η(%) mean values ± 1SD were equal to 50 ± 10, 73 ± 7, and 86 ± 6 for DP, MP, and CP aerosols, respectively. The R f and CR mean values ± 1SD were equal to 0.16 ± 0.05 μm and 1.3 ± 0.3, respectively, for DP aerosols; to 0.12 ± 0.03 μm and 1.8 ± 0.4, respectively, for MP aerosols; and to 0.11 ± 0.02 μm and 1.7 ± 0.4, respectively, for CP aerosols. CP and DP aerosols were on average responsible for greater AOT and LR values, but the LR and AOT dependence on wavelength was stronger for CP than for DP aerosols. The plots of the lidar ratio values at 355 nm versus the mean columnar values of the 532–1064 nm Ångström coefficient (Å c), the fine mode radius, the fine mode fraction at 532 nm (η c), and the color ratio, respectively, furthermore revealed the greater ability of the Å c and η c values to characterize different aerosol types.
Mostrar más [+] Menos [-]Oxidoreductases provide a more generic response to metallic stressors (Cu and Cd) than hydrolases in soil fungi: new ecotoxicological insights
2016
Lebrun, Jérémie D. | Demont-Caulet, Nathalie | Cheviron, Nathalie | Laval, Karine | Trinsoutrot-Gattin, Isabelle | Mougin, Christian
The present study investigates the effect of metals on the secretion of enzymes from12 fungal strains maintained in liquid cultures. Hydrolases (acid phosphatase, β-glucosidase, β-galactosidase, and N-acetyl-β-glucosaminidase) and ligninolytic oxidoreductases (laccase, Mn, and lignin peroxidases) activities, as well as biomass production, were measured in culture fluids from fungi exposed to Cu or Cd. Our results showed that all fungi secreted most of the selected hydrolases and that about 50 % of them produced a partial oxidative system in the absence of metals. Then, exposure of fungi to metals led to the decrease in biomass production. At the enzymatic level, Cu and Cd modified the secretion profiles of soil fungi. The response of hydrolases to metals was contrasted and complex and depended on metal, enzyme, and fungal strain considered. By contrast, the metals always stimulated the activity of ligninolytic oxidoreductases in fungal strains. In some of them, oxidoreductases were specifically produced following metal exposure. Fungal oxidoreductases provide a more generic response than hydrolases, constituting thus a physiological basis for their use as biomarkers of metal exposure in soils.
Mostrar más [+] Menos [-]Indoor air quality at life and work environments in Rome, Italy
2016
Romagnoli, P. | Balducci, C. | Perilli, M. | Vichi, F. | Imperiali, A. | Cecinato, A.
The air quality of three different microenvironments (school, dwelling, and coffee bar) located in the city of Rome, Italy, was assessed. Indoor and outdoor concentrations of polycyclic aromatic hydrocarbons (PAHs) associated with PM₂.₅ particles were determined during an intensive 3-week sampling campaign conducted in March 2013. In interiors, total particulate PAHs ranged from 1.53 to 4.96 ng/m³ while outdoor air contained from 2.75 to 3.48 ng/m³. In addition, gaseous toxicants, i.e., NO₂, NO ₓ , SO₂, O₃, and BTEX (benzene, toluene, ethyl-benzene, and xylene isomers), were determined both in internal and external air. To solve the origin of indoor and outdoor PAHs, several source apportionment methods were applied. Multivariate analysis revealed that emissions from motor vehicles, biomass burning for heating purposes, and soil resuspension were the major sources of PAHs in the city. No linear correlation was established between indoor and outdoor values for PM₂.₅ and BTEX; the respective indoor/outdoor concentration ratios exceed unity except for PM₂.₅ in the no smoking home and benzene in all school floors. This suggests that important internal sources such as tobacco smoking, cleaning products, and resuspension dust contributed to indoor pollution. Using the monitoring stations of ARPA Lazio regional network as reference, the percentage within PAH group of benzo[a]pyrene, which is the WHO marker for the carcinogenic risk estimates, was ca. 50 % higher in all locations investigated.
Mostrar más [+] Menos [-]Plant tolerance to mercury in a contaminated soil is enhanced by the combined effects of humic matter addition and inoculation with arbuscular mycorrhizal fungi
2016
Cozzolino, V. | De Martino, A. | Nebbioso, A. | Di Meo, V. | Salluzzo, A. | Piccolo, A.
In a greenhouse pot experiment, lettuce plants (Lactuca sativa L.) were grown in a Hg-contaminated sandy soil with and without inoculation with arbuscular mycorrhizal fungi (AMF) (a commercial inoculum containing infective propagules of Rhizophagus irregularis and Funneliformis mosseae) amended with different rates of a humic acid (0, 1, and 2 g kg⁻¹ of soil), with the objective of verifying the synergistic effects of the two soil treatments on the Hg tolerance of lettuce plants. Our results indicated that the plant biomass was significantly increased by the combined effect of AMF and humic acid treatments. Addition of humic matter to soil boosted the AMF effect on improving the nutritional plant status, enhancing the pigment content in plant leaves, and inhibiting both Hg uptake and Hg translocation from the roots to the shoots. This was attributed not only to the Hg immobilization by stable complexes with HA and with extraradical mycorrhizal mycelium in soil and root surfaces but also to an improved mineral nutrition promoted by AMF. This work indicates that the combined use of AMF and humic acids may become a useful practice in Hg-contaminated soils to reduce Hg toxicity to crops.
Mostrar más [+] Menos [-]Spatiotemporal analysis for the effect of ambient particulate matter on cause-specific respiratory mortality in Beijing, China
2016
Wang, Xuying | Guo, Yuming | Li, Guoxing | Zhang, Yajuan | Westerdahl, Dane | Jin, Xiaobin | Pan, Xiaochuan | Chen, Liangfu
This study explored the association between particulate matter with an aerodynamic diameter of less than 10 μm (PM₁₀) and the cause-specific respiratory mortality. We used the ordinary kriging method to estimate the spatial characteristics of ambient PM₁₀ at 1-km × 1-km resolution across Beijing during 2008–2009 and subsequently fit the exposure-response relationship between the estimated PM₁₀ and the mortality due to total respiratory disease, chronic lower respiratory disease, chronic obstructive pulmonary disease (COPD), and pneumonia at the street or township area levels using the generalized additive mixed model (GAMM). We also examined the effects of age, gender, and season in the stratified analysis. The effects of ambient PM₁₀ on the cause-specific respiratory mortality were the strongest at lag0-5 except for pneumonia, and an inter-quantile range increase in PM₁₀ was associated with an 8.04 % (95 % CI 4.00, 12.63) increase in mortality for total respiratory disease, a 6.63 % (95 % CI 1.65, 11.86) increase for chronic lower respiratory disease, and a 5.68 % (95 % CI 0.54, 11.09) increase for COPD, respectively. Higher risks due to the PM₁₀ exposure were observed for females and elderly individuals. Seasonal stratification analysis showed that the effects of PM₁₀ on mortality due to pneumonia were stronger during spring and autumn. While for COPD, the effect of PM₁₀ in winter was statistically significant (15.54 %, 95 % CI 5.64, 26.35) and the greatest among the seasons. The GAMM model evaluated stronger associations between concentration of PM₁₀. There were significant associations between PM₁₀ and mortality due to respiratory disease at the street or township area levels. The GAMM model using high-resolution PM₁₀ could better capture the association between PM₁₀ and respiratory mortality. Gender, age, and season also acted as effect modifiers for the relationship between PM₁₀ and respiratory mortality.
Mostrar más [+] Menos [-]A review of the characterization and revegetation of bauxite residues (Red mud)
2016
Xue, Shengguo | Zhu, Feng | Kong, Xiangfeng | Wu, Chuan | Huang, Ling | Huang, Nan | Hartley, William
Bauxite residue (Red mud) is produced in alumina plants by the Bayer process in which Al-containing minerals are dissolved in hot NaOH. The global residue inventory reached an estimated 3.5 billion tons in 2014, increasing by approximately 120 million tons per annum. The appropriate management of bauxite residue is becoming a global environmental concern following increased awareness of the need for environmental protection. Establishment of a vegetation cover is the most promising way forward for the management of bauxite residue, although its physical and chemical properties can limit plant growth due to high alkalinity and salinity, low hydraulic conductivity, trace element toxicity (Al and Fe), and deficiencies in organic matter and nutrition concentrations. This paper discusses the various revegetation and rehabilitation strategies. Studies of the rehabilitation of bauxite residues have mainly focused on two approaches, amelioration of the surface layer and screening of tolerant plants and soil microorganisms. Amendment with gypsum can reduce the high alkalinity and salinity, promote soil aggregation, and increase the hydraulic conductivity of bauxite residues. Organic matter can provide a source of plant nutrients, form stable complexes with metal cations, promote hydraulic conductivity, stabilize soil structure, and provide an energy source for soil organisms. Tolerant plants and microorganisms such as halophytes and alkaliphilic microbes show the greatest potential to ameliorate bauxite residues. However, during restoration or as a result of natural vegetation establishment, soil formation becomes a critical issue and an improved understanding of the various pedogenic processes are required, and future direction should focus on this area.
Mostrar más [+] Menos [-]Effects of operating conditions on trihalomethanes formation and speciation during chloramination in reclaimed water
2016
Wang, Fang | Gao, Baoyu | Ma, Defang | Li, Ruihua | Sun, Shenglei | Yue, Qinyan | Wang, Yan | Li, Qian
In this study, a hybrid powdered activated carbon-membrane bioreactor (PAC-MBR) system was used to treat municipal wastewater in northern China intended for recycle. In order to control microbiological hazards in PAC-MBR effluent, chloramine was chosen as the disinfectant which could reduce the disinfection by-product yields. Effects of reaction time, chloramines dose, pH value, and bromide ion concentration on trihalomethanes (THMs) formation and speciation during chloramination of the reclaimed effluent were investigated. Study results indicated that the yield of total THMs (TTHM) increased at higher reaction time and chloramines dose. The trend of growth showed that slow reacting precursors were the main components of dissolved organic matter (DOM) in PAC-MBR effluent. THMs formation potential of PAC-MBR effluent achieved the maximum at chloramines dosage of 20 mg/L. Meanwhile, THMs formation was enhanced evidently under alkaline conditions. The yields of THMs species were in following order: CHCl₃ > CHBrCl₂ > CHBr₂Cl > CHBr₃, although in different reaction time, chloramines dose, and pH value. Furthermore, the formation of Br-THMs was promoted by the increasing concentration of bromide ion.
Mostrar más [+] Menos [-]Influence of selected anti-cancer drugs on the induction of DNA double-strand breaks and changes in gene expression in human hepatoma HepG2 cells
2016
Novak, Matjaž | Žegura, Bojana | Baebler, Špela | Štern, Alja | Rotter, Ana | Stare, Katja | Filipič, Metka
In chemotherapy, various anti-cancer drugs with different mechanisms of action are used and may represent different risk of undesirable delayed side effects in treated patients as well as in occupationally exposed populations. The aim of the present study was to evaluate genotoxic potential of four widely used anti-cancer drugs with different mechanisms of action: 5-fluorouracil (5-FU), cisplatin (CDDP) and etoposide (ET) that cause cell death by targeting DNA function and imatinib mesylate (IM) that inhibits targeted protein kinases in cancer cells in an experimental model with human hepatoma HepG2 cells. After 24 h of exposure all four anti-cancer drugs at non-cytotoxic concentrations induced significant increase in formation of DNA double strand breaks (DSBs), with IM being the least effective. The analysis of the changes in the expression of genes involved in the response to DNA damage (CDKN1A, GADD45A, MDM2), apoptosis (BAX, BCL2) and oncogenesis (MYC, JUN) showed that 5-FU, CDDP and ET upregulated the genes involved in DNA damage response, while the anti-apoptotic gene BCL2 and oncogene MYC were downregulated. On the contrary, IM did not change the mRNA level of the studied genes, showing different mechanism of action that probably does not involve direct interaction with DNA processing. Genotoxic effects of the tested anti-cancer drugs were observed at their therapeutic concentrations that may consequently lead to increased risk for development of delayed adverse effects in patients. In addition, considering the genotoxic mechanism of action of 5-FU, CDDP and ET an increased risk can also not be excluded in occupationally exposed populations. The results also indicate that exposure to 5-FU, CDDP and ET represent a higher risk for delayed effects such as cancer, reproductive effects and heritable disease than exposure to IM.
Mostrar más [+] Menos [-]Evaluation of environmental quality of two estuaries in Ilha do Maranhão, Brazil, using histological and genotoxic biomarkers in Centropomus undecimalis (Pisces, Centropomidae)
2016
Cantanhêde, Sildiane Martins | da Silva Castro, Geane | Pereira, Natália Jovita | de Pinho Campos, Jonas Silva | da Silva, Juliana | Tchaicka, Lígia | Neta, Raimunda Nonata Fortes Carvalho | de Souza Torres, José Ribamar, Jr | Santos, Débora Martins Silva
Estuaries are subjected to continual environmental impacts from activities in the catchment areas. This research assessed the quality of two estuarine habitats located in Ilha do Maranhão, Brazil, through histological and genotoxic biomarkers in Centropomus undecimalis, comparing the data obtained to metal, physical, and chemical concentrations of water samples. The gill histological alterations were analyzed by the histological alteration index and genotoxic lesions in erythrocytes were detected by the Micronucleus Test. The analysis of metals revealed that all water samples contained at least two elements with concentrations higher than that allowed by the current Brazilian law. For gill histological analysis, snook of both areas assessed exhibited moderate lesions, indicating that the local fish are affected by environmental stress. Micronucleus analysis of snook showed that the Bacanga river basin is the most affected. In addition to assessing the health of commercial fish populations, the information about the biomarkers used for the species can serve to contribute to the preparation and/or application of health assessment models and implementation of environmental recovery policies for coastal aquatic environments.
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