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Iván N. Pérez-Maldonado Antonio Trejo-Acevedo Sandra Teresa Orta-García Ángeles C. Ochoa-Martinez José Antonio Varela-Silva Francisco Javier Pérez-Vázquez 《Journal of environmental science and health. Part. B》2013,48(2):87-93
The aim of this study was to assess the levels of dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) in the blood of children living in the southeastern region of Mexico. In this study, we found high levels of DDT and its principal metabolite (DDE) in the blood of children residing in the communities studied. The levels of total DDT found in our study ranged from 4,676.4 ng/g lipid to 64,245.2 ng/g lipid. All of the children in the study had detectable levels of DDT and/or DDE. In conclusion, our data indicate that children living within the study areas are exposed to high levels of DDT and DDE. Moreover, these results can be used as a trigger to revisit local policies on environmental exposures. 相似文献
324.
Esther García-de Blas Rafael Mateo Francisco Javier Guzmán Bernardo Rosa Carmen Rodríguez Martín-Doimeadios Carlos Alonso-Alvarez 《Die Naturwissenschaften》2014,101(5):407-416
Carotenoids are organic pigments involved in several important physiological functions and may serve as indicators of individual quality in animals. These pigments are only obtained by animals from the diet, but they can be later transformed into other carotenoids by specific enzymatic reactions. The diet of farm-reared and probably wild red-legged partridges (Alectoris rufa) is mainly based on cereals that contain high levels of lutein and zeaxanthin. These two carotenoids are also predominant in internal tissues and blood of red-legged partridges. However, in their integuments, astaxanthin and papilioerythrinone (the last one identified in this work) are mainly present in their free form and esterified with fatty acids. According to available literature about carotenoid metabolism in animals, we propose that astaxanthin (λ max?=?478 nm) and papilioerythrinone (λ max?=?452–478 nm) are the result of a chromatic convergence of the transformation of dietary zeaxanthin and lutein, respectively. Moreover, the results obtained in this work provide the first identification by liquid chromatography coupled to accurate mass quadrupole time-of-flight mass spectrometer system of papilioerythrinone (m/z 581.3989 [M?+?H]+) in the skin (i.e., not feathers) of a vertebrate. Astaxanthin and papilioerythrinone are very close in terms of chemical structure and coloration, and the combination of these two keto-carotenoids is responsible for the red color of the ornaments in red-legged partridges. 相似文献
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Marcela M.C. Campos Vanessa H.F. Faria Taciane S. Teodoro Francisco A.R. Barbosa Sérgia M.S. Magalhães 《Journal of environmental science and health. Part. B》2013,48(2):101-107
The bioaccumulation of atrazine and its toxicity were evaluated for the cyanobacterium Microcystis novacekii. Cyanobacterial cultures were grown in WC culture medium with atrazine at 50, 250 and 500 μg L?1. After 96 hours of exposure, 27.2% of the atrazine had been removed from the culture supernatant. Spontaneous degradation was found to be insignificant (< 9% at 500 μg L?1), indicating a high efficiency for the bioaccumulation of atrazine by M. novacekii. There were no atrazine metabolites detected in the culture medium at any of the doses studied. The acute toxicity (EC50) of atrazine to the cyanobacterium was 4.2 mg L?1 at 96 hours demonstrating the potential for M. novacekii to tolerate high concentrations of this herbicide in fresh water environments. The ability of M. novacekii to remove atrazine combined with its tolerance of the pesticide toxicity showed in this study makes it a potential biological resource for the restoration of contaminated surface waters. These findings support continued studies of the role of M. novacekii in the bioremediation of fresh water environments polluted by atrazine. 相似文献
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Luis F. de Diego Margarita de las Obras-Loscertales Francisco García-Labiano Aránzazu Rufas Alberto Abad Pilar Gayán Juan Adánez 《International Journal of Greenhouse Gas Control》2011,5(5):1190-1198
CO2 and SO2 are some of the main polluting gases emitted into atmosphere in combustion processes using fossil fuel for energy production. The former is one of the major contributors to build-up the greenhouse effect implicated in global climate change and the latter produces acid rain. Oxy-fuel combustion is a technology, which consists in burning the fuel with a mix of pure O2 and recirculated CO2. With this technology the CO2 concentration in the flue gas may be enriched up to 95%, becoming possible an easy CO2 recovery. In addition, oxy-fuel combustion in fluidized beds allows in situ desulfurization of combustion gases by supplying calcium based sorbent.In this work, the effect of the principal operation variables affecting the sulfation reaction rate in fluidized bed reactors (temperature, CO2 partial pressure, SO2 concentration and particle size) under typical oxy-fuel combustion conditions have been analyzed in a batch fluidized bed reactor using a limestone as sorbent. It has been observed that sulfur retention can be carried out by direct sulfation of the CaCO3 or by sulfation of the CaO (indirect sulfation) formed by CaCO3 calcination. Direct sulfation and indirect sulfation operating conditions depended on the temperature and CO2 partial pressure. The rate of direct sulfation rose with temperature and the rate of indirect sulfation for long reaction times decreased with temperature. An increase in the CO2 partial pressure had a negative influence on the sulfation conversion reached by the limestone due to a higher temperature was needed to work in conditions of indirect sulfation. Thus, it is expected that the optimum temperature for sulfur retention in oxy-fuel combustion in fluidized bed reactors be about 925–950 °C. Sulfation reaction rate rose with decreasing sorbent particle size and increasing SO2 concentration. 相似文献
329.
Francisco Alvarez-Cuadrado Ngo Van Long 《Journal of Environmental Economics and Management》2009,58(2):154-168
This paper proposes a welfare criterion that balances the need for development and the concern for the least advantaged generations, and explores its implications. This criterion, called the mixed Bentham–Rawls criterion, moderates the effect of discounting, yet permits some degree of intertemporal trade-off. It is a weighted average of two terms: (a) the sum of discounted utilities and (b) the utility level of the least advantaged generation. We derive necessary conditions to characterize growth paths that satisfy our criterion, and show that in some models with familiar dynamic specifications, an optimal path exists and displays appealing characteristics. 相似文献
330.
Marco Antonio Leonel Caetano Douglas Francisco Marcolino Gherardi 《Ecological modelling》2011,222(15):2835-2840
The Brazilian government has already acknowledged the importance of investing in the development and application of technologies to reduce or prevent CO2 emissions resulting from human activities in the Legal Brazilian Amazon (BA). The BA corresponds to a total area of 5 × 106 km2 from which 4 × 106 km2 was originally covered by the rain forest. One way to interfere with the net balance of greenhouse gases (GHG) emissions is to increase the forest area to sequester CO2 from the atmosphere. The single most important cause of depletion of the rain forest is cattle ranching. In this work, we present an effective policy to reduce the net balance of CO2 emissions using optimal control theory to obtain a compromising partition of investments in reforestation and promotion of clear technology to achieve a CO2 emission target for 2020. The simulation indicates that a CO2 emission target for 2020 of 376 million tonnes requires an estimated forest area by 2020 of 3,708,000 km2, demanding a reforestation of 454,037 km2. Even though the regional economic growth can foster the necessary political environment for the commitment with optimal emission targets, the reduction of 38.9% of carbon emissions until 2020 proposed by Brazilian government seems too ambitious. 相似文献