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181.
Aida Garcia-Rodríguez Víctor Matamoros Clàudia Fontàs Victòria Salvadó 《Chemosphere》2013,90(8):2297-2302
The effect of aquatic vegetation (Spyrogira sp. and Zannichellia palustris), light exposure and water quality (secondary-treated wastewater vs. ultrapure water) on the removal efficiency of six antibiotics (sulfonamides and tetracyclines) is studied in laboratory-scale reactors. After 20 d of treatment, 3–59% of sulfonamides were eliminated in the reactors exposed to light. Removal was about 10% in unplanted reactors in darkness. The elimination of tetracycline (TC) and oxytetracycline (OTC) ranged between 83% and 97% in both planted and unplanted reactors. However, in dark unplanted reactors, OTC was largely removed (88%) while only 15% of TC was eliminated. These results suggest that TC was mainly removed by photodegradation whereas biodegradation or hydrolysis process seems to be significant processes for OTC. Sulfonamides were mainly eliminated by biodegradation or indirect photodegradation processes. Pseudo-first order kinetics removal rates ranged from 0.003 and 0.007 d?1 for Sulfamethazine and TC in the covered control reactors to 0.13 and 0.21 d?1 for TC and OTC in the uncovered control reactors, with half-lives from 3 to 350 d. A TC photodegradation product was tentatively identified in uncovered reactors. This study highlights the important role played by light exposure in the elimination of antibiotics in polishing ponds. 相似文献
182.
Régia Maria Avancini Iandara Schettert Silva Ana Cristina Simões Rosa Paula de Novaes Sarcinelli Sueli Alexandra de Mesquita 《Chemosphere》2013,90(9):2408-2413
Organochlorines are highly hydrophobic, synthetic organic pollutants that accumulate in the environment and in food webs. The primary route of human exposure to organochlorines is through food-mainly fat-rich food of animal origin such as meat, fish, and dairy products. Here we determined the presence and concentration of organochlorine residues in pasteurized milk from Mato Grosso do Sul, Brazil, to monitor consumer exposure to these contaminants. Organochlorine pesticides in milk samples were analyzed using solid phase extraction in octadecyl silica-prepacked columns and identified by gas chromatography using an electron capture detector. Of the 100 composite samples analyzed, more than 90% contained residues of organochlorine pesticides: aldrin was present in 44% of the samples, followed by ∑DDT (36%), mirex (34%), endosulfan (32%), chlordane (17%), dicofol (14%), heptachlor (11%) and dieldrin (11%). Compared to the values established by law, the concentration of the compounds in some samples was above the reference values. Given the importance that milk and its products have in the human diet, it is essential to know whether the levels of pesticide residues are kept well below the recommended levels to minimize the risk to human health. 相似文献
183.
Nicresse L. Guedegba Ibrahim Imorou Toko Prudencio T. Agbohessi Berny’s Zoumenou Caroline Douny Syaghalirwa N.M. Mandiki 《Journal of environmental science and health. Part. B》2013,48(7):580-589
AbstractThis study aimed to compare the toxicity for fish of two active ingredients (lambda-cyhalothrin-20?g L?1, a pyrethroid, and acetamiprid-15?g L?1, a neonicotinoid) which are components of a commercial insecticide (Acer 35 EC) used in cotton crop in many West African countries. The juveniles of Oreochromis niloticus (4.01?±?0.34?g, mean body weight) were exposed for 96?h to increasing concentrations of active ingredients (lambda-cyhalothrin and acetamiprid) or a mixture similar to Acer 35 EC (composed by 20?g of chemical compound lambda-cyhalothrin and 15?g of acetamiprid dissolved in 1?L of acetone). The experiments were carried out under controlled conditions in aquaria according to OECD Guidelines. During the experiments, the behavioral responses (loss of balance, color change, hyperactivity, etc.) that usually precede death were observed in exposed fish. Mortalities were recorded in each aquarium and the LC50-96h of each chemical was determined. The LC50-96h obtained were respectively 0.1268, 0.0029, 182.9 and 0.5685?ppm for Acer 35 EC, lambda-cyhalothrin, acetamiprid and mixture. All insecticides used in this study had profound impact on Nile tilapia behavior which may confirm the neurotoxicity of each single active compound as well as of their mixture. 相似文献
184.
Luís Costa Kirsten Thonicke Benjamin Poulter Franz-W. Badeck 《Regional Environmental Change》2011,11(3):543-551
Within the changing fire regimes of Portugal, the relative importance of humans and climatic variability for regional fire
statistics remains poorly understood. This work investigates the statistical relationship between temporal dynamics of fire
events in Portugal and a set of socioeconomic, landscape, and climatic variables for the time periods of 1980–1990, 1991–2000,
and extreme fires years. For 10 of 15 districts, it was possible to observe moderate shifts in the significance of fire drivers
for the first two decadal periods. For others, pronounced changes of the significance of fire drivers were found across time.
Results point toward a dynamic (perhaps highly non-linear) behavior of socioeconomic and landscape fire drivers, especially
during the occurrence of extreme fire years of 2003 and 2005. At country level, population density alone explained 42% of
the inter-annual and inter-district deviance in number of fires. At the same temporal and spatial scale, the explanatory power
of temperature anomalies proved to explain 43% of area burnt. We highlight the necessity of including a broad set of socioeconomic
and landscape fire drivers in order to account for potential significance shifts. In addition, although climate does trigger
broad favorable fire conditions across Portugal mainland, socioeconomic and landscape factors proved to determine much of
the complex fire patterns at a subnational scale. 相似文献
185.
Marc Gracia Nacima Meghelli Lluís Comas Javier Retana 《Regional Environmental Change》2011,11(2):349-358
The current state of Mediterranean mountain areas has been driven by two main factors: intense traditional human activity
and the dynamics of the ecosystem itself. In this study, we examine land-cover changes in a National Park in the Pyrenees
mountains (NE Iberian Peninsula), which was designated a protected area 55 years ago. First, we have analyzed spatio-temporal
changes in land-cover pattern and forest dynamics from 1957 to 2005. During this period, land-cover dynamics consisted of
two main processes: (i) expansion of the forest area and (ii) increasing cover of forests already present in 1957. To analyze
the role of the conservation level of the park, we have also compared the results obtained within the park with those of unprotected,
peripheral areas. In the two areas with different protection level, dense forests increased throughout the period because
of the reduction in forestry activities. The peripheral area showed a higher rate of forest-cover change from 1957 to 2005
compared to the National Park. This higher increase in forest cover in the peripheral area could be related to a higher proportion
in the National Park of screes and rocky areas and to the decline and transformation of forest activities in these peripheral,
lower elevation areas. 相似文献
186.
Nogueira L Sanches AL da Silva DG Ferrizi VC Moreira AB de Almeida EA 《Chemosphere》2011,85(1):97-105
Fossil fuels such as diesel are being gradually replaced by biodiesel, a renewable energy source, cheaper and less polluting. However, little is known about the toxic effects of this new energy source on aquatic organisms. Thus, we evaluated biochemical biomarkers related to oxidative stress in Nile tilapia (Oreochromis niloticus) after two and seven exposure days to diesel and pure biodiesel (B100) and blends B5 and B20 at concentrations of 0.01 and 0.1 mL L−1. The hepatic ethoxyresorufin-O-deethylase activity was highly induced in all groups, except for those animals exposed to B100. There was an increase in lipid peroxidation in liver and gills in the group exposed to the higher concentration of B5. All treatments caused a significant increase in the levels of 1-hydroxypyrene excreted in the bile after 2 and 7 d, except for those fish exposed to B100. The hepatic glutathione-S-transferase increased after 7 d in animals exposed to the higher concentration of diesel and in the gill of fish exposed to the higher concentration of pure diesel and B5, but decreased for the two tested concentrations of B100. Superoxide dismutase, catalase and glutathione peroxidase also presented significant changes according to the treatments for all groups, including B100. Biodiesel B20 in the conditions tested had fewer adverse effects than diesel and B5 for the Nile tilapia, and can be suggested as a less harmful fuel in substitution to diesel. However, even B100 could activate biochemical responses in fish, at the experimental conditions tested, indicating that this fuel can also represent a risk to the aquatic biota. 相似文献
187.
Microcosm experiments to control anaerobic redox conditions when studying the fate of organic micropollutants in aquifer material 总被引:1,自引:0,他引:1
188.
Rundqvist S Hedenås H Sandström A Emanuelsson U Eriksson H Jonasson C Callaghan TV 《Ambio》2011,40(6):683-692
Shrubs and trees are expected to expand in the sub-Arctic due to global warming. Our study was conducted in Abisko, sub-arctic
Sweden. We recorded the change in coverage of shrub and tree species over a 32– to 34-year period, in three 50 × 50 m plots;
in the alpine-tree-line ecotone. The cover of shrubs and trees (<3.5 cm diameter at breast height) were estimated during 2009–2010
and compared with historical documentation from 1976 to 1977. Similarly, all tree stems (≥3.5 cm) were noted and positions
determined. There has been a substantial increase of cover of shrubs and trees, particularly dwarf birch (Betula nana), and mountain birch (Betula pubescens ssp. czerepanovii), and an establishment of aspen (Populus tremula). The other species willows (Salix spp.), juniper (Juniperus communis), and rowan (Sorbus aucuparia) revealed inconsistent changes among the plots. Although this study was unable to identify the causes for the change in shrubs
and small trees, they are consistent with anticipated changes due to climate change and reduced herbivory. 相似文献
189.
This study was conducted in the Swedish sub-Arctic, near Abisko, in order to assess the direction and scale of possible vegetation
changes in the alpine–birch forest ecotone. We have re-surveyed shrub, tree and vegetation data at 549 plots grouped into
61 clusters. The plots were originally surveyed in 1997 and re-surveyed in 2010. Our study is unique for the area as we have
quantitatively estimated a 19% increase in tree biomass mainly within the existing birch forest. We also found significant
increases in the cover of two vegetation types—“birch forest-heath with mosses” and “meadow with low herbs”, while the cover
of snowbed vegetation decreased significantly. The vegetation changes might be caused by climate, herbivory and past human
impact but irrespective of the causes, the observed transition of the vegetation will have substantial effects on the mountain
ecosystems. 相似文献
190.
Concentration of trace elements in feathers of three Antarctic penguins: Geographical and interspecific differences 总被引:1,自引:0,他引:1
Silvia JerezMiguel Motas María José PalaciosFrancisco Valera José Javier Cuervo Andrés Barbosa 《Environmental pollution (Barking, Essex : 1987)》2011,159(10):2412-2419
Antarctica is often considered as one of the last pristine regions, but it could be affected by pollution at global and local scale. Concentrations of Al, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Cd and Pb were determinated by ICP-MS in feathers (n = 207 individuals) of gentoo, chinstrap and Adélie penguin collected in 8 locations throughout the Antarctic Peninsula (2006-2007). The highest levels of several elements were found in samples from King George Island (8.08, 20.29 and 1.76 μg g−1 dw for Cr, Cu and Pb, respectively) and Deception Island (203.13, 3.26 and 164.26 μg g−1 dw for Al, Mn and Fe, respectively), where probably human activities and large-scale transport of pollutants contribute to increase metal levels. Concentrations of Cr, Mn, Cu, Se or Pb, which are similar to others found in different regions of the world, show that some areas in Antarctica are not utterly pristine. 相似文献