خيارات البحث
النتائج 1 - 10 من 120
Is microbial population associated to ectomycorrhized roots of Norway spruces in Krkonose National Park influenced by forest decline?
2002
Martinotti, M.G. (University of Piemonte Orientale, Novara (Italy)) | Avidano, L. | Fracchia, L.
Investigations on the bacterial communities associated to ectomycorrhized roots of seedlings from three stands with different degrees of regeneration decline (high, intermediate and low) and from seedlings grown on monoliths obtained from the very same stands have been carried out. The results suggest that forest decline does not influence bacterial biomass associated to seedlings roots but induce a clustering of specific bacterial species adapted to the different degree of forest decline
اظهر المزيد [+] اقل [-]Air pollution status and forest health in the Retezat National Park, Romania
2002
Badea, O. (Forest Research Institute, Bucharest (Romania)) | Popescu, F. | Barbu, I. | Bytnerowicz, A. | Musselman, R. | Gancz, V. | Postelicu, D. | Vasile, C.
Ozone is a well-known phytotoxic agent causing damage to vegetation in parts of North America and Europe. Transboundary or long-range transport of ozone from Western Europe and the generation of ozone from local and regional precursors results in increasing ozone concentrations in Central and Eastern Europe, including the Carpathian Mountaians. Other air pollutants such as sulphur dioxide, nitrogen oxides, ammonia and heavy metals may also affect the health of Carpathian forests. During the 2000-2002 summer seasons, concentrations of ozone, sulphur dioxide, nitrogen oxides and ammonia were monitored with passive samplers. Results of those measurements will be used for development of GIS models of spatial and temporal distribution of air pollutants
اظهر المزيد [+] اقل [-]Heavy metals and pedogenic processes in the Krkonose National Park (Czech Republic)
2002
Bonifacio, E. | Santoni, S. | Zanini, E. (Universita di Torino, Grugliasco (Italy). DIVAPRA Chimica Agraria)
Remarkable differences were found in soil development on three sites. At Modru Dul (the least damaged site) Sopdosols and Inceptisols were found, in Alzbetinska (moderately damaged) Entisols are common, while in Mumlavksa hora (highly damaged) the representative soils are several kind of Podzols, with variable degree of drainage restriction and organic soils. The heavy metal content is always rather low and the vertical distribution does not indicate any appreciable contribution of atmospheric contamination
اظهر المزيد [+] اقل [-]Spatial variability of some topsoil character in a declining forest site (Krkonose National Park, Czech Republic)
2002
Zanini, E. | Caimi, A. | Santoni, S. | Bonifacio, E. (DIVAPRA-Chimica Agraria, Grugliasco (Italy))
45 sites were selected and sampled on the transects and according to the first results of the spatial analysis, 15 more sites were added where useful for the optimal interpolation. Topsoils were sampled including both the soil organic horizons and the more superficial mineral horizon, frequently E, if reached. The depth of the organic horizons, the grass cover, ranked by its hydrophilic character, related to the incipient hydromorphy visible where Norway spruce is more declining, and the Norway spruce health status were systematically recorded
اظهر المزيد [+] اقل [-]Redox and global interconnected proteome changes in mice exposed to complex environmental hazards surrounding Doñana National Park
2019
Michán, Carmen | Chicano-Gálvez, Eduardo | Fuentes-Almagro, Carlos A. | Alhama, José
Natural environments are receiving an increasing number of contaminants. Therefore, the evaluation and identification of early responses to pollution in these complex habitats is an urgent and challenging task. Doñana National Park (DNP, SW Spain) has been widely used as a model area for environmental studies because, despite its strictly protected core, it is surrounded by numerous threat sources from agricultural, mining and industrial activities. Since many pollutants often induce oxidative stress, redox proteomics was used to detect redox-based variations within the proteome of Mus spretus mice captured in DNP and the surrounding areas. Functional analysis showed that most differentially oxidized proteins are involved in the maintenance of homeostasis, by eliciting mechanisms to respond to toxic substances and oxidative stress, such as antioxidant and biotransformation processes, immune and inflammatory responses, and blood coagulation. Furthermore, changes in the overall protein abundance were also analysed by label-free quantitative proteomics. The upregulation of phase I and II biotransformation enzymes in mice from Lucio del Palacio may be an alert for organic pollution in the area located at the heart of DNP. Metabolic processes involved in protein turnover (proteolysis, amino acid catabolism, new protein biosynthesis and folding) were activated in response to oxidative damage to these biomolecules. Consequently, aerobic respiratory metabolism increased to address the greater ATP demands. Alterations of cholesterol metabolism that could cause hepatic steatosis were also detected. The proteomic detection of globally altered metabolic and physiological processes offers a complete view of the main biological changes caused by environmental pollution in complex habitats.
اظهر المزيد [+] اقل [-]Methylmercury photodemethylation is inhibited in lakes with high dissolved organic matter
2018
Klapstein, Sara J. | Ziegler, Susan E. | O'Driscoll, Nelson J.
Photodemethylation can be one of the primary processes for loss of neurotoxic methylmercury (MeHg) in freshwater lakes. Few studies have quantified seasonal variations in photodemethylation rate constants as a function of dissolved organic matter (DOM). We conducted 1-week irradiation experiments in two seasons to test for spatial and temporal differences in photodemethylation potential in temperate lake waters. Six study lakes in Kejimkujik National Park, Nova Scotia were sampled in summer and fall to include a range of naturally occurring DOM concentrations (4.4–13.4 and 3.9–16.4 mg C L⁻¹, respectively). A negative linear relationship (R² = 0.76, p = 0.01) was found between DOM concentration and photodemethylation rate constant across seasons, indicating that DOM is a strong predictor of MeHg photodemethylation independent of seasonal effects. The two highest carbon lakes (BDW and PEB) had significantly higher energy-normalized photodemethylation rate constants in summer compared to fall corresponding with lower DOM concentrations in summer relative to fall. Additionally, there were negative linear relationships between MeHg photodemethylation and DOM photomineralization (R²s = 0.58–0.72) and DOM photobleaching (R²s = 0.83–0.90). This key finding suggests that competition for photons within DOM structures may reduce the potential for MeHg photodemethylation in high carbon waters and that this relationship persists across seasons.
اظهر المزيد [+] اقل [-]Nutrients, heavy metals and microbial communities co-driven distribution of antibiotic resistance genes in adjacent environment of mariculture
2017
Zhao, Zelong | Wang, Jing | Han, Ying | Chen, Jingwen | Liu, Guangfei | Lu, Hong | Yan, Bin | Chen, Shiaoshing
With the rapid development of aquaculture, the large amounts of pollutants were discharged into the aquatic environment, where the detected antibiotic resistance genes (ARGs) have drawn increasing attention due to their potential threats to ecological environment and human health. Thus, the impact of mariculture on ARGs was assessed and the underlying mechanism of their propagation was explained. Sediments from eight sampling sites were collected along a mariculture drainage ditch, and the sediment in Yellow River Delta National Park was used as a non-mariculture control. Microbial ARGs qPCR array and illumina sequencing of 16S rRNA gene were applied to examine the changing patterns of ARGs and bacterial communities. Results showed that 18 ARGs (3 fluoroquinolone, 1 aminoglycoside, 3 macrolide-lincosamide-streptogramin B, 2 tetracycline, and 9 beta-lactam resistance genes) were influenced by mariculture, and ARGs abundance and diversity were significantly increased in mariculture sediments (p < 0.05). A remarkable shift in bacterial community structure and composition was also observed. The abundance of most of ARGs were significantly decreased in the estuary samples, implying that seawater had a significant dilution effect on the ARGs emission from the mariculture sites. Partial redundancy analysis showed that nutrients, heavy metals, and bacteria communities might directly and indirectly contribute to ARGs propagation, suggesting that the profile and dissemination of ARGs were driven by the combined effects of multiple factors in mariculture-impacted sites.
اظهر المزيد [+] اقل [-]The role of a peri-urban forest on air quality improvement in the Mexico City megalopolis
2012
Baumgardner, Darrel | Varela, Sebastian | Escobedo, Francisco J. | Chacalo, Alicia | Ochoa, Carlos
Air quality improvement by a forested, peri-urban national park was quantified by combining the Urban Forest Effects (UFORE) and the Weather Research and Forecasting coupled with Chemistry (WRF-Chem) models. We estimated the ecosystem-level annual pollution removal function of the park’s trees, shrub and grasses using pollution concentration data for carbon monoxide (CO), ozone (O₃), and particulate matter less than 10 microns in diameter (PM₁₀), modeled meteorological and pollution variables, and measured forest structure data. Ecosystem-level O₃ and CO removal and formation were also analyzed for a representative month. Total annual air quality improvement of the park’s vegetation was approximately 0.02% for CO, 1% for O₃, and 2% for PM₁₀, of the annual concentrations for these three pollutants. Results can be used to understand the air quality regulation ecosystem services of peri-urban forests and regional dynamics of air pollution emissions from major urban areas.
اظهر المزيد [+] اقل [-]Annual and seasonal trends of ambient ozone concentration and its impact on forest vegetation in Mercantour National Park (South-eastern France) over the 2000–2008 period
2011
Sicard, Pierre | Dalstein-Richier, Laurence | Vas, Nicolas
In the South-Eastern French Mediterranean region, high ozone concentrations were measured since many years and specific symptoms like chlorotic mottles were detected on Arolla pines. We presented results for the 2000–2008 period concerning the trend analysis for ambient ozone concentrations and related forest damages, with the Mann and seasonal Kendall tests. Ozone precursor’s emissions from Europe have been reduced over the last 20 years. Decreases in annual averages, median, 25th and 98th percentiles and maxima values were found. The seasonal trend analysis for the high-lying stations showed a decreasing trend for the warm season, when main ozone production is the photochemistry, and an increase for the cold period, caused by a reduced ozone titration. Statistics on Arolla Pine reveal strong correlations between mottling intensity and the high ozone concentrations. Finally, decreases for the ozone concentrations, and associated statistics, AOT40 values and for the mottling intensity on conifers needles were observed.
اظهر المزيد [+] اقل [-]Estimating contribution of wildland fires to ambient ozone levels in National Parks in the Sierra Nevada, California
2010
Preisler, Haiganoush K. | Chung, S. Y (Sze Yuen) | Esperanza, Annie | Brown, Timothy J. | Bytnerowicz, Andrzej | Tarnay, Leland
monitoring sites operated by the National Park Service in Sierra Nevada, California, are used to develop an ozone forecasting model and to estimate the contribution of wildland fires on ambient ozone levels. The analyses of weather and ozone data pointed to the transport of ozone precursors from the Central Valley as an important source of pollution in these National Parks. Comparisons of forecasted and observed values demonstrated that accurate forecasts of next-day hourly ozone levels may be achieved by using a time series model with historic averages, expected local weather and modeled PM values as explanatory variables. Results on fire smoke influence indicated occurrence of significant increases in average ozone levels with increasing fire activity. The overall effect on diurnal ozone values, however, was small when compared with the amount of variability attributed to sources other than fire. We have demonstrated that it is possible to produce accurate forecasts of next-day hourly ozone levels in the Sierra Nevada, CA, during fire season.
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