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21.
Jaqueline García-Hernández Lázaro Cadena-Cárdenas Miguel Betancourt-Lozano Luz Maria García-De-La-Parra Leticia García-Rico Fernando Márquez-Farías 《毒物与环境化学》2013,95(3):507-522
Fish at the top of the food chain bioaccumulate and biomagnify toxic metals including mercury (Hg), at a higher rate than nonpredatory fish. However, although some top predator fish species are important in the human diet, the risks for consumers in Mexico are difficult to evaluate due to the scarce baseline information available. In the present article, data on the total mercury (THg) concentrations found in edible tissues of different species of sharks, rays, large pelagic fishes and groupers from the Gulf of California are presented and compared with national and international health guidelines. During 2003 and 2004, 73 shark dorsal tissue samples, 52 ray samples, 66 large pelagic fish samples and 16 grouper samples were collected at different sites along the Gulf of California. Samples were digested in a microwave system and analyzed by cold vapor atomic absorption spectrophotometry. Thirty samples (14%) showed concentrations of Hg above the national statutory limit of 1?mg?kg?1, from which 25 samples were sharks and 3 were large pelagic fishes. A positive correlation was found between the natural log of THg [ln(THg)] and total length (TL cm) in species of sharks, rays and groupers. The Teacapán estuary in Sinaloa was detected as a possible source of Hg into the Gulf of California due to historic mining in the watershed. Mean Hg concentrations exceeded the regulatory limit of 1?mg?kg?1 in the following highly commercial shark species: smooth hammerhead, pelagic thrasher, pacific sharpnose shark, dusky shark, scalloped hammerhead, and whitenose shark, in that order. It is recommended that preventive food advisories be issued with respect to these species until further investigations are conducted. 相似文献
22.
Ana P. L. Batista Hudson Wallace Pereira Carvalho Gustavo H. P. Luz Paulo F. Q. Martins Maraísa Gonçalves Luiz C. A. Oliveira 《Environmental Chemistry Letters》2010,8(1):63-67
A photocatalyst based on CuO/SiO2 was prepared, and evaluated for the degradation of methylene blue in aqueous medium. The photocatalyst was obtained by calcination
method of copper salt, in the presence of silica. The characterization by XRD, FTIR, and TPR techniques confirmed the formation
of CuO as active phase. SEM studies showed CuO deposited on the surface of SiO2. By ESI-MS, it was demonstrated that the degradation of methylene blue occurs through successive hydroxylations. Photodegradation
assays showed that CuO/SiO2 was efficient for degradation, and that the material worked better in the presence of UV light. 相似文献
23.
Martha P. García De Llasera Leopoldo Cruz-Reyes Luz E. Vera-Avila 《Journal of environmental science and health. Part. B》2013,48(1):25-32
A method based on matrix solid-phase dispersion (MSPD) was developed for quantitative extraction of three organophosphorus pesticides (OPPs) from the Mexican axolotl, Ambystoma mexicanum. The determination was carried out using high- performance liquid chromatography (HPLC) with diode array spectrophotometric UV detection (DAD). The MSPD extraction with octadecylsilyl (C18) sorbent combined with a silica gel clean-up and acetonitrile elution was optimised for chlorpyrifos, fenthion and methyl parathion. The method was validated, yielding recovery values higher than 90%. The precision, expressed as the relative standard deviation (RSD), was less than or equal to 6% in muscle samples at spiking levels of 10 and 5 ppm. Linearity was studied from 15 to 60 ppm for chlorpyrifos and fenthion, and from 7.5 to 30 ppm for methyl parathion. The limits of detection (LODs) were found to be less than or equal to 0.5 ppm.This method was applied to the analysis of samples from a chlorpyrifos-exposed axolotl, demonstrating its use as an analytical tool for toxicological studies. 相似文献
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25.
Levario-Carrillo M Amato D Ostrosky-Wegman P González-Horta C Corona Y Sanin LH 《Chemosphere》2004,55(10):1421-1427
The increased use of organophosphorus insecticides in agriculture and their widespread existence in the environment poses a potential health hazard. To determine the relationship between exposure to pesticides and intrauterine growth retardation (IUGR), live newborns from singleton pregnancies, with (n = 79) and without (n = 292) IUGR were studied. During the gestational period the mothers were living in agricultural communities in the state of Chihuahua, Mexico. Exposure to agrochemical products was evaluated. A significant association between the history of positive exposure to pesticides (i.e. the women themselves or their newborns who showed acetylcholinesterase activity levels lower than 20%) and the presence of IUGR was found. The proportions of exposure in the cases were 18% and 8% in the control group; the adjusted OR (fat free mass, anti-cytomegalovirus antibodies and placental weight) was 2.33 (p = 0.04). 相似文献
26.
Marco Antonio DS Guidugli-Lazzarini KR do Nascimento AM Simões ZL Hartfelder K 《Die Naturwissenschaften》2008,95(10):953-961
The switch from within-hive activities to foraging behavior is a major transition in the life cycle of a honeybee (Apis mellifera) worker. A prominent regulatory role in this switch has long been attributed to juvenile hormone (JH), but recent evidence
also points to the yolk precursor protein vitellogenin as a major player in behavioral development. In the present study,
we injected vitellogenin double-stranded RNA (dsVg) into newly emerged worker bees of Africanized genetic origin and introduced them together with
controls into observation hives to record flight behavior. RNA interference-mediated silencing of vitellogenin gene function shifted the onset of long-duration flights (>10 min) to earlier in life (by 3–4 days) when compared with sham
and untreated control bees. In fact, dsVg bees were observed conducting such flights extremely precociously, when only 3 days
old. Short-duration flights (<10 min), which bees usually perform for orientation and cleaning, were not affected. Additionally,
we found that the JH titer in dsVg bees collected after 7 days was not significantly different from the controls. The finding
that depletion of the vitellogenin titer can drive young bees to become extremely precocious foragers could imply that vitellogenin
is the primary switch signal. At this young age, downregulation of vitellogenin gene activity apparently had little effect on the JH titer. As this unexpected finding stands in contrast with previous results
on the vitellogenin/JH interaction at a later age, when bees normally become foragers, we propose a three-step sequence in
the constellation of physiological parameters underlying behavioral development.
David Santos Marco Antonio and Karina Rosa Guidugli-Lazzarini contributed equally to the present study. 相似文献
27.
Some organisms use morphological structures obtained by behavioural processes to lower mortality by predation. We test whether
larvae of the limnephilid caddisfly Potamophylax latipennis (Curtis) vary their responses to the presence of different predators (dragonfly naiads, fire salamander larvae or brown trout)
by choosing organic or mineral cases. We offered both case types to larvae, and simulated differences in predation risk using
water conditioned with chemicals from the different predators. Our results show that Potamophylax larvae detect and discriminate predators using water-borne chemical cues and alter their choice of case type according to
the perceived predation risk. Moreover, the distribution of larvae bearing cases of different anti-predator value matches
the spatial variation in predation risk in the field. 相似文献
28.
A preliminary investigation has been made on the emissions of Polynuclear Aromatic Hydrocarbons (PAH) when burning wood chips and peat in a modified commercial hot water boiler. The amount of the investigated eighteen PAH that were filter trapped from peat combustion averaged 2.7 times greater than that from wood combustion per cubic meter flue gas. The total emitted amount (particulate plus gas phase PAH) was 9.7 times greater than from wood combustion. The corresponding values for benzo(a)pyrene only were 1.7 and 3.5 times greater, respectively. The comparison of PAH emitted by the combustion of wood and peat showed a pronounced tendency towards the emission of high molecular weight PAH by the latter.Particulate phase-gas phase distribution ourves are presented for PAH in the boiling point range 336°C – 525°C. In addition, the emission of a polynuclear aromatic ketone is shown. 相似文献
29.
Baptista Manuela C. da Luz Garcia M. Pinho Sílvia C. Ascensão Lopes M. Almeida Manuel F. Coelho Carlos Fonseca Carlos 《Journal of Material Cycles and Waste Management》2021,23(4):1445-1455
Journal of Material Cycles and Waste Management - The increased consumption of polymers and the consequent generation of waste requires the development of efficient recycling strategies. In this... 相似文献
30.
da Luz Garcia Maria Oliveira M. Rosário Silva Teresa Neto Castro Ana C. Meira 《Journal of Material Cycles and Waste Management》2021,23(2):699-706
Journal of Material Cycles and Waste Management - The massive amount of plastic production inevitably leads to huge levels of pollution and, consequently, is threatening the environment and... 相似文献