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71.
A.?J.?Pazos A.?Silva V.?Vázquez M.?L.?Pérez-Parallé J.?L.?Sánchez M.?AbadEmail author 《Marine Biology》2005,147(3):663-670
The sterol composition of three different populations of Ruditapes decussatus from three localities close to each other, but where different environment conditions prevail, was investigated over a period of 14 months. Sterols of adult clams were isolated by thin layer chromatography and identified by gas chromatography/mass spectrometry. In all samples, the major sterol component was cholesterol (>40% of total sterols); other sterols identified were 24-norcholesta-5,22-dienol, 22-cis-dehydrocholesterol, 22-trans-dehydrocholesterol, brassicasterol, 24-methylene-cholesterol, campesterol, stigmasterol, -sitosterol and isofucosterol. At each locality, changes in sterol levels followed specific and different patterns, which remained constant for the period studied and allowed the origin of the clams to be distinguished. Stepwise discriminant analysis, based on the percentage amounts of the sterols at each locality, indicated brassicasterol, 22-cis-dehydrocholesterol, cholesterol, 24-norcholestadienol and -sitosterol as discriminant variables that distinguish clam populations. Correct identification of the clam origin was achieved in 100% of the samples, demonstrating that sterols can justifiably be used as molecular biomarkers for determining the origin of this bivalve species.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
72.
This study evaluated the potential toxicological risk posed to human health due to the exposure to heavy metals by water ingestion
in an area affected by tanneries – the Cadeia-Feitoria hydrographic basin (Brazil). River water was collected at 10 sites,
every 3 months, from July 1999 to April 2000. After acid digestion, total metal concentration was determined by inductively
coupled plasma optical emission spectrometry (Cd, Cu, Cr, Ni, Zn), flame atomic absorption (Al, Fe, Pb, Mn), or cold vapor
atomic absorption spectrometry (Hg). Cr(VI) was complexed with diphenyl-carbazide and detected by UV–vis spectrometry. In
order to quantify the risk of exposure, the risk assessment methodology employed by the Environmental Protection Agency of
the United States was applied at a screening level. The assumed scenarios included extreme exposure patterns (ingestion of
untreated water, conversion of Cr(III) to Cr(VI), temporal peaks of pollution). Fe, Al, Cd, Hg, and Pb were not included in
the risk analysis, since they showed a low toxicity potential or were undetected in the samples. The selected metals presented
Hazard Quotients < 1, in the following order of increasing risk: Cu < Cr(III) < Zn < Ni < Mn < Cr(VI). Hazard indexes, representing
the additive effect of contaminants, were also low in the basin (< 1), but comparatively increased in the lower reach of Feitoria
and Cadeia Rivers. Although noncarcinogenic risk levels did not suggest possible adverse toxicological effects to the human
population, a considerable deviation from background conditions was observed downstream the area where tanneries are mainly
located. 相似文献
73.
M. I. Silva H. D. Burrows S. J. Formosinho L. Alves A. Godinho M. J. Antunes D. Ferreira 《Environmental Chemistry Letters》2007,5(3):143-149
Advanced oxidation processes, such as photocatalysed oxidation, provide an important route for degradation of wastes. In this
study, the lowest excited state (3MLCT) of Ru(bpy)32+ is used to break down chlorophenol pollutant molecules to harmless products. This has the advantage of using visible light
and a short-lived catalytically active species. Photolysis of deaerated aqueous solutions of a variety of mono- and poly-substituted
chlorophenols has been followed in the presence of Ru(bpy)32+/S2O82− with near visible light (λ > 350 nm) by UV/visible absorption spectroscopy, luminescence, potentiometry, NMR and HPLC techniques.
Upon irradiation, a decrease is observed in the chlorophenol concentration, accompanied by the formation of Cl−, H+ and SO42− ions as the main inorganic products. Benzoquinone, phenol, dihydroxybenzenes and chlorinated compounds were the dominant
organic products. As the ruthenium(II) complex is regenerated in the reaction, the scheme corresponds to an overall catalytic
process. The kinetics of the rapid chlorophenol photodechlorination has been studied, and are described quite well by pseudo-first
order behaviour. Further studies on this were made by following Cl− release with respect to the initial Ru(bpy)32+ and S2O82− concentrations. A comparison is presented of the photodechlorination reactivity of the mono and polychlorophenols studied
at acidic and alkaline pH. 相似文献
74.
The kinetics of copper bioaccumulation in the rock oyster Crassostrea cucullata Born showed that the initial rate of uptake was directly related to metal concentration in the medium. As the accumulation in the tissues increased, the oysters remained closed and the uptake rate fell. At the end of 7 weeks, the average copper concentrations in the tissue were 60.42 g g-1 and 63.97 g g-1 wet weight in the 0.01 and 0.05 ppm experimental groups, respectively. The net rate of uptake ranged from 1.76 to 1.97 g g-1 week-1 and the rate of copper loss, measured after transferring the oysters into natural sea water, was dependent on the original cooper concentration in the soft parts. The concentration of copper in the tissues declined by 37.38 and 36.56% in the 0.01 and 0.05 ppm experimental groups, respectively. Even after a 7 week period of depuration (self-purification) there was some residual copper left in the tissue. This indicates that accumulation occurs in the tissue more rapidly than cleansing can eliminate it. 相似文献
75.
Elie Gaget Diego Pavón-Jordán Alison Johnston Aleksi Lehikoinen Wesley M. Hochachka Brett K. Sandercock Alaaeldin Soultan Hichem Azafzaf Nadjiba Bendjedda Taulant Bino Luka Božič Preben Clausen Mohamed Dakki Koen Devos Cristi Domsa Vitor Encarnação Kiraz Erciyas-Yavuz Sándor Faragó Teresa Frost Clemence Gaudard Lívia Gosztonyi Fredrik Haas Menno Hornman Tom Langendoen Christina Ieronymidou Vasiliy A. Kostyushin Lesley J. Lewis Svein-Håkon Lorentsen Leho Luigujõe Włodzimierz Meissner Tibor Mikuska Blas Molina Zuzana Musilová Viktor Natykanets Jean-Yves Paquet Nicky Petkov Danae Portolou Jozef Ridzoň Samir Sayoud Marko Šćiban Laimonas Sniauksta Antra Stīpniece Nicolas Strebel Norbert Teufelbauer Goran Topić Danka Uzunova Andrej Vizi Johannes Wahl Marco Zenatello Jon E. Brommer 《Conservation biology》2021,35(3):834-845
Climate warming is driving changes in species distributions and community composition. Many species have a so-called climatic debt, that is, shifts in range lag behind shifts in temperature isoclines. Inside protected areas (PAs), community changes in response to climate warming can be facilitated by greater colonization rates by warm-dwelling species, but also mitigated by lowering extirpation rates of cold-dwelling species. An evaluation of the relative importance of colonization-extirpation processes is important to inform conservation strategies that aim for both climate debt reduction and species conservation. We assessed the colonization-extirpation dynamics involved in community changes in response to climate inside and outside PAs. To do so, we used 25 years of occurrence data of nonbreeding waterbirds in the western Palearctic (97 species, 7071 sites, 39 countries, 1993–2017). We used a community temperature index (CTI) framework based on species thermal affinities to investigate species turnover induced by temperature increase. We determined whether thermal community adjustment was associated with colonization by warm-dwelling species or extirpation of cold-dwelling species by modeling change in standard deviation of the CTI (CTISD). Using linear mixed-effects models, we investigated whether communities in PAs had lower climatic debt and different patterns of community change than communities outside PAs. For CTI and CTISD combined, communities inside PAs had more species, higher colonization, lower extirpation, and lower climatic debt (16%) than communities outside PAs. Thus, our results suggest that PAs facilitate 2 independent processes that shape community dynamics and maintain biodiversity. The community adjustment was, however, not sufficiently fast to keep pace with the large temperature increases in the central and northeastern western Palearctic. Our results underline the potential of combining CTI and CTISD metrics to improve understanding of the colonization-extirpation patterns driven by climate warming. 相似文献
76.
Euglena gracilis as a model for the study of Cu and Zn toxicity and accumulation in eukaryotic cells
Marcelo Einicker-Lamas Gustavo Antunes Mezian Thiago Benevides Fernandes Fabio Leandro S. Silva Flvio Guerra Kildare Miranda Marcia Attias Mecia M. Oliveira 《Environmental pollution (Barking, Essex : 1987)》2002,120(3)
We have observed the effect of copper and zinc on the biology of Euglena gracilis. The cells displayed different sensitivities to these metals, as the apparent LC50 for Cu2+ was 0.22 mM, and for Zn2+ it was 0.88 mM. While Zn2+ was able to increase cell proliferation even at 0.1 mM, the minimal CuCl2 concentration tested (0.02 mM) was sufficient to impair cell division. Higher concentrations of these metals not only inhibited cell division in a concentration-dependent manner, but also interfered with the metabolism of E. gracilis. A higher accumulation of proteins and lipids per cell was observed at the DI50 concentration for metal-treated cells. These results suggest that the test concentration of both metals leads to a failure in completing cell division. Ultrastructural analysis indicated a chloroplast disorganization in copper-treated cells, as well as the presence of electron dense granules with different shapes and sizes inside vacuoles. Microanalysis of these granules indicated an accumulation of copper, thus suggesting a detoxification role played by the vacuoles. These results indicate that E. gracilis is an efficient biological model for the study of metal poisoning in eukaryotic cells. They also indicate that copper and zinc (copper being more poisonous) had an overall toxic effect on E. gracilis and that part of the effect can be ascribed to defects in the structure of chloroplast membranes. 相似文献
77.
Treatment and detoxification of a sanitary landfill leachate 总被引:10,自引:0,他引:10
The leachate from an old sanitary landfill (Gramacho Metropolitan Landfill, Rio de Janeiro) was characterized and submitted to coagulation and flocculation treatment followed by ozonation and ammonia stripping. The performance of the treatment was assessed by monitoring the removal of organic matter (COD and TOC), ammonium nitrogen and metals. Detoxification was assessed by determining acute toxicity, using the following organisms: Vibrio fisheri, Daphnia similis, Artemia salina and Brachydanio rerio. Membrane fractionation was employed to infer the range of molecular masses of the pollutants found in the effluent, as well as the toxicity associated to these fractions. Of the techniques under investigation, coagulation and flocculation followed by ammonia stripping were the most effective for toxicity and ammonium nitrogen removal. Membrane fractionation was effective for COD removal; however, acute toxicity was almost the same in all the fractionated samples. Ozonation was moderately effective for COD removal, but significant toxicity removal was only attained when high ozone doses were used. 相似文献
78.
The effect of annual variations in the daily average soil temperatures, at different depths, on the calculation of pesticide leaching potential indices is presented. This index can be applied to assess the risk of groundwater contamination by a pesticide. It considers the effects of water table depth, daily recharge net rate, pesticide sorption coefficient, and degradation rate of the pesticide in the soil. The leaching potential index is frequently used as a screening indicator in pesticide groundwater contamination studies, and the temperature effect involved in its calculation is usually not considered. It is well known that soil temperature affects pesticide degradation rates, air-water partition coefficient, and water-soil partition coefficient. These three parameters are components of the attenuation and retardation factors, as well as the leaching potential index, and contribute to determine pesticide behavior in the environment. The Arrhenius, van't Hoff, and Clausius-Clapeyron equations were used in this work to estimate the soil temperature effect on pesticide degradation rate, air-water partition coefficient, and water-soil partition coefficient, respectively. The relationship between leaching potential index and soil temperature at different depths is presented and aids in the understanding of how potential pesticide groundwater contamination varies on different climatic conditions. Numerical results will be presented for 31 herbicides known to be used in corn and soybean crops grown on the municipality of S?o Gabriel do Oeste, Mato Grosso do Sul State, Brazil. 相似文献
79.
Brayner FM da Silva HK Barbosa AM 《Environmental science and pollution research international》2001,8(4):269-274
An analytical procedure involving a three-step sequential extraction was used to determine the chemical association of heavy metals (Zn, Cr, Mn and Fe) with the major phases (exchangable, reducible and oxidizable) in samples from a fishpond of estuarine sediments. The pond is located in the Capibaribe River estuary, within the boundaries of the city of Recife, in the State of Pernambuco in the northeast of Brazil. The total metal content was determined as well. All metals were extracted from the residual fraction at a percentage greater than 50%. 相似文献
80.
Juliana Aparecida Diniz Leonardo Luiz Okumura Herbert Aleixo Alexandre Gurgel Astréa Filomena Souza Silva 《Journal of environmental science and health. Part. B》2020,55(6):583-591
AbstractAn original voltammetric screening method, employing glassy carbon electrode (GCE) with the differential-pulse voltammetry technique (DPV), has been developed to determine residues of the anti-parasitic agent Ronidazole (RNZ) in bovine meat. By using cyclic voltammetry (CV), it has been demonstrated that an irreversible cathodic process occurs at approximately ?0.740?V (vs. Ag|AgCl, KCl 3?mol L?1) in a 0.100?mol L?1 phosphate buffer at pH 6.5 as supporting electrolyte. Furthermore, the behavior of RNZ in CV indicates the occurrence of a diffusion mass transfer process to the working electrode surface. The RNZ reduction mechanism was proposed as a 6-electron transfer, similar to Metronidazole under the same pH range. Quantification of RNZ and method validation were then carried out by DPV. The relative standard deviation (RSD) were 3.21% for intraday precision of 10 consecutive repetitions and 6.78% for interday precision after five analysis. Limits of detection and quantification were also obtained, and the values were 0.107 and 0.358?mg kg?1, respectively. The recovery percentage for three different concentrations of RNZ in the bovine meat matrix ranged between 98.1% and 100.3%. The method proved to be efficient for screening RNZ in bovine meat. 相似文献