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421.
Algarra M Jiménez MV Rodríguez-Castellón E Jiménez-López A Jiménez-Jiménez J 《Chemosphere》2005,59(6):779-786
The potential of removing nickel and copper from industrial electroplating wastewaters by using mesoporous materials with MCM-41 type structure functionalised with different ratios of aminopropyl groups, namely Na50, Na25 and Na5, were evaluated. The synthesised solids sorbents obtained were characterised by X-ray diffraction, elemental chemical analysis and IR spectroscopy. In preliminary experiments, studies were carried out to determine the optimal experimental conditions for the retention of heavy ions. Effects of concentration, optimal pH, interference with humic substances and other metals were studied for Na5, which showed the best capacity of absorption determined by the corresponding isotherm. This material has a greater selectivity against sodium, indicating that ionic strength does not affect the extraction. Results of an application of this material to remove nickel and copper in synthetic and real industrial wastewater samples from an electrochemical industry area are shown with successful results. The lowest level of nickel and copper were observed when Na5 was used. This observation suggests that reactive aminopropyl-Si MCM-41 and similar materials may be a promising and provide for alternative environmental technologies in the future. 相似文献
422.
Peñalber-Ramos J Méndez-Tejeda R Rodríguez-Rosario M 《Journal of the Air & Waste Management Association (1995)》2002,52(6):719-721
Acid rain precipitation has become a major environmental concern. Many long-range projects in the United States and Europe are devoted to the problems associated with acid rain pollution. In Puerto Rico, there has been no formal study on acid rain. The rainfall pH values and the air-mass trajectory of the northeastern part of the island of Puerto Rico on the surface were analyzed from January 1998 to December 2000. The air-mass trajectory was classified in five different sectors, according to where it originates. The mean pH value measured during that period showed a tendency toward acidity. The 80% of the air-mass trajectory that arrived at the station occurred in Sector I, with a pH value of 4.30. The lowest pH value measured was 4.16, and it occurred in Sector V, where the air mass originates in the northwest part of the island. 相似文献
423.
Changes in total lipids, lipid classes and their fatty acid contents were studied in the ovaries and midgut glands ofPenaeus kerathurus Forskäl females during sexual maturation. The shrimp were captured in the Gulf of Cádiz (southwest Spain) in 1990. The lipid content and fatty acids, in relative terms, increased during ovarian development. The greatest changes occurred between Maturation Stages III and IV. Ovarian lipids were dominated by polar classes, whereas in the midgut gland the major classes were triacylglycerols and sterol esters. The amounts of major fatty acids in ovaries (16:0, 16:1n-7, 18:1n-9, 18:1n-7, 20:5n-3 and 22:6n-3) increased with increasing maturity, but declined slightly between Stages III and IV. The total polar lipid content of the midgut was 5.7% (by dry weight) and its fatty acid composition remained constant during the whole study period. Total lipid content of the midgut gland showed an upward trend during sexual maturation, except between Stages II and III, when a slight decrease was observed. Predominant fatty acids in the midgut gland (16:1n-7, 20:5n-3 and 22:6n-3) displayed a noteworthy decline between Stages II and III, corresponding with the marked increase in total lipid fatty acid content in the ovaries during the same period. 相似文献
424.
Evelyn B. Pluhar 《Journal of Agricultural and Environmental Ethics》1988,1(3):211-224
Professor Hugh Lehman has recently argued that the rights view, according to which nonhuman animals have a prima facie right to life, is compatible with the killing of animals in many circumstances, including killing for food, research, or product-testing purposes. His principle argument is an appeal to life-boat cases, in which certain lives should be sacrificed rather than others because the latter would allegedly be made worse-off by death than the former. I argue that this reasoning would apply to so-called inferior humans just as much as to animals, and that this appeal is unsuccessful in any case. I distinguish two versions of the rights view: the equal and the unequal rights views. Although the unequal rights view, unlike the equal rights view, would sanction the killing of animals (and some humans) for food under severely restricted circumstances, neither rights view sanctions the raising of animals for their meat. Moreover, neither rights view would sanction the killing of animals for research or product-testing purposes. I conclude with a brief discussion of the merits of phasing out the meat production industry. 相似文献
425.
426.
Influence of soil texture on the distribution and availability of 238U, 230Th, and 226Ra in soils 总被引:1,自引:0,他引:1
Blanco Rodríguez P Vera Tomé F Lozano JC Pérez-Fernández MA 《Journal of environmental radioactivity》2008,99(8):1247-1254
The influence of soil texture on the distribution and availability of (238)U, (230)Th, and (226)Ra in soils was studied in soil samples collected at a rehabilitated uranium mine located in the Extremadura region in south-west Spain. The activity concentration (Bqkg(-1)) in the soils ranged from 60 to 750 for (238)U, from 60 to 260 for (230)Th, and from 70 to 330 for (226)Ra. The radionuclide distribution was determined in three soil fractions: coarse sand (0.5-2mm), medium-fine sand (0.067-0.5mm), and silt and clay (<0.067 mm). The relative mobility of the natural radionuclides in the different fractions was studied by comparison of the activity ratios between radionuclides belonging to the same radioactive series. The lability of these radionuclides in each fraction was also studied through selective extraction from the soils using a one-step sequential extraction scheme. Significant correlations were found for (238)U, (230)Th, and (226)Ra between the activity concentration per fraction and the total activity concentration in the bulk soil. Thus, from the determination of the activity concentration in the bulk soil, one could estimate the activity concentration in each fraction. Correlations were also found for (238)U and (226)Ra between the labile activity concentration in each fraction and the total activity concentration in bulk soil. Assuming that there is some particle-size fraction that predominates in the process of soil-to-plant transfer, the parameters obtained in this study should be used as correction factors for the transfer factors determined from the bulk soil in previous studies. 相似文献
427.
María J. Darias Harry M. Murray Jeffrey W. Gallant Susan E. Douglas Manuel Yúfera Gonzalo Martínez-Rodríguez 《Marine Biology》2007,152(1):109-118
A restoration programme was introduced in the Mondego Estuary (Portugal) to recover seagrass beds of Zostera noltii endangered by eutrophication. A long-term survey of 10 years was used to assess the development of the processes involved,
focusing one of the key species (Cyathura carinata, Isopoda). The mitigation measures implemented since 1998 (nutrient loading reduction, freshwater circulation improvement
and seagrass bed protection) enhanced water quality and seagrass recovery, thus preventing the development of macroalgal blooms.
C. carinata was resilient to the occurrence of floods and macroalgal blooms, although both events caused dispersion of individuals. This
isopod was not much influenced by the changes occurring in the estuary, showing an unalterable population structure during
the entire study period. After 1998, its density and biomass became more stable at an inner unvegetated sand flat area, where
this isopod was most abundant; its population slightly increased in a bare mud flat at the middle section of the estuary;
but it could not establish successfully in a downstream Z. noltii bed, contrarily to other common estuarine species. Apart from other unknown reasons, the disrupted balanced between trematodes
and their hosts, caused by the eutrophication processes, may have an important role in the discontinuity of C. carinata at the Z. noltii bed. If the intertidal areas become fully restored to the original seagrass coverage, high prevalence and intensity trematodes
may prevent this isopod and other crustaceans from recovering within the intervened areas, by enhancing host mortality and
recruitment failure. In order to avoid this kind of situation, it may be necessary to survey the levels of parasite infestation
within the target hosts and safeguard areas where crustaceans present healthy populations. 相似文献
428.
Vector optimization techniques were used to generate arbitrary segments of a policy frontier for a dynamic yellowfin tuna (Thunnus albacares) fishery model assuming fixed technology and considering four policy objectives: minimizing dolphin mortality, minimizing incidental catch (all species except dolphins), maximizing sustainable yield, and minimizing biological risk for the yellowfin tuna stock. Results show that along the policy frontier: (1) reducing incidental dolphin mortality increases the incidental catch of other species in a nonlinear way; (2) yield increases (subject to a biomass precautionary level) can only be obtained at the expense of higher levels of dolphin mortality and incidental catch; (3) biological risk increases as the level of tunas caught increases, but this increase depends on the type of fishery (longline fishing and three different modes of purse-seining: log-sets, dolphin-sets or school-sets) that dominates the fishing effort; (4) there is an indirect relationship between the dolphin mortality levels and those of biological risk; (5) there is a direct relationship between the incidental catch levels and biological risk. Catch obtained with dolphin-sets dominates the Pareto-optimal solutions with highest dolphin mortality levels but is associated with lower biological risk, whereas catch obtained with log-sets dominates in Pareto-optimal solutions with higher incidental catch and higher biological risk. In general, trade-offs or shadow prices among objectives are not linear, indicating that marginal costs vary along the policy frontier. Results of the trade-off analysis may provide useful information for decision-makers and other policy actors. Complete information about the preferences of the decision-makers regarding the objectives is necessary to recommend a specific management policy. 相似文献
429.
Within its distribution range in the northeastern Atlantic, the stalked barnacle Pollicipes pollicipes shows a well-defined pattern of genetic variation, comprising (a) a subtropical/temperate northern assemblage, made up of
populations distributed between 47°N and 28°N along the French, Iberian, North African and Canary Islands coastlines, and
(b) a single isolated and highly divergent tropical population in the Cape Verde Islands (16°N), at the southernmost limit
of the species’ distribution. However, within the northern assemblage several populations show a level of genetic differentiation
that allows rejection of the hypothesis of genetic homogeneity. The congruence observed between genetic and hydrographic patterns
suggests a crucial role of hydrodynamics, and of the dispersal of the planktonic larvae, in the determination of population
structure. Along the southern European Atlantic coast, the Iberian Poleward Current and mesoscale hydrographic structures
are, respectively, facilitating gene flow at the regional level and genetic differentiation at the local level. On the Atlantic
coast of North Africa, the homogenizing equatorward flow of the Canary Current does not extend as far as the Cape Verde Islands.
A demographic expansion is dated to the late Pleistocene, preceding the Eemian interglacial, and is oldest in the case of
the long-standing Cape Verde population, sustained by a stable tropical habitat. The divergence between the Cape Verde population
and the remaining populations is thus ancient, and suggests that oceanic current patterns may constitute a generalized physical
barrier to the dispersal of marine organisms between Cape Verde and the rest of Macaronesia. 相似文献
430.
F. Rodríguez M. Chauton G. Johnsen K. Andresen L.M. Olsen M. Zapata 《Marine Biology》2006,148(5):963-971
Chl a and C-normalized pigment ratios were studied in two dinophytes (Prorocentrum minimum and Karlodinium micrum), three haptophytes (Chrysochromulina leadbeateri, Prymnesium parvum cf. patelliferum, Phaeocystis globosa), two prasinophytes (Pseudoscourfieldia marina, Bathycoccus prasinos) and the raphidophyte Heterosigma akashiwo, in low (LL, 35 μmol photons m−2 s−1) and high light (HL, 500 μmol photons m−2 s−1). Pigment ratios in LL and HL were compared against a general rule of photoacclimation: LL versus HL ratios ≥1 are typical
for light-harvesting pigments (LHP) and <1 for photoprotective carotenoids. Peridinin, prasinoxanthin, gyroxanthin-diester
and 19′-butanoyloxy-fucoxanthin were stable chemotaxonomic markers with less than 25% variation between LL versus HL Chl a–normalized ratios. As expected, Chls exhibited LL/HL to Chl a ratios >1 with some exceptions such as Chl c
3 in P. globosa and MV Chl c
3 in C. leadbeateri. LL/HL to Chl a ratios of photosynthetic carotenoids were close to 1, except Hex-fuco in P. globosa (four-fold higher Chl a ratio in HL vs LL). Although pigment ratios in P. globosa clearly responded to the light conditions the diadinoxanthin-diatoxanthin cycle remained almost unaltered at HL. Total averaged
pigment and LHP to C ratios were significantly higher in LL versus HL, reflecting the photoacclimation status of the studied
species. By contrast, the same Chl a-normalized ratios were weakly affected by the light intensity due to co-variation with Chl a. Based on our data, we suggest that the interpretation of PPC and LHP are highly dependent on biomass normalization (Chl
a vs. C). 相似文献