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711.
The giant Amazon river turtle (Podocnemis expansa) nests on extensive sand bars on the margins and interior of the channel during the dry season. The high concentration of nests in specific points of certain beaches indicates that the selection of nest placement is not random but is related to some geological aspects, such as bar margin inclination and presence of a high, sandy platform. The presence of access channels to high platform points or ramp morphology are decisive factors in the choice of nesting areas. The eroded and escarped margins of the beaches hinder the Amazon river turtle arriving at the most suitable places for nesting. Through the years, changes in beach morphology can alter nest distribution. 相似文献
712.
Mestres R 《Environmental science and pollution research international》2005,12(3):128-132
Background and Goal The object of Green Chemistry is the reduction of chemical pollutants flowing to the environment. The Chemistry and the Environment Division of EuCheMS has assumed Green Chemistry as one of its areas of interest, but one question to solve is where Green Chemistry should be placed within the context of Chemistry and the Environment. The concept of Green Chemistry, as primarily conceived by Paul Anastas and John Warner, is commonly presented through the Twelve Principles of Green Chemistry. However, these Twelve Principles, though fruit of a great intuition and common sense, do not provide a clear connection between aims, concepts, and related research areas of Green Chemistry. These two unsolved questions are the object of the present article.Discussion Green Chemistry is here placed as a part of Chemistry for the Environment, concerning the still non-existent pollutants. Indeed, the object of Green Chemistry is the reduction of pollution and risks by chemicals by avoiding their generation or their introduction into the biosphere. The distinction between pollutant chemicals and dangerous chemicals, along with the consideration of the exhaustion of fossil resources and the acknowledgement of the harmful effects of the chemicals employed in a great variety of activities, leads to the recognition of four general objectives for Green Chemistry. In order to accomplish these general objectives, a number of strategies, or secondary objectives and some fundamental concepts, namely, atomic economy, selectivity, potential harm or historical harm can be visualized. A connection is finally established between the strategies and current and future research areas of Green Chemistry.Conclusion The ultimate aim of green chemistry is to entirely cut down the stream of chemicals pouring into the environment. This aim seems unattainable at present, but progress in the green chemical research areas and their application through successive approaches will certainly provide safer specialty chemicals and much more satisfactory processes for the chemical industry.- * The basis of this peer-reviewed paper is a presentation at the 9th FECS Conference on Chemistry and Environment, 29 August to 1 September 2004, Bordeaux, France. 相似文献
713.
Martín-Gil J Martín-Gil FJ del Carmen Ramos-Sánchez M Martín-Ramos P 《Environmental science and pollution research international》2005,12(5):285-289
Goal, Scope and Background In this paper, we attempt to elucidate the composition and origin of the orange patina on the surfaces of the West-Porch
of Salisbury Cathedral by comparison to other known patinas: (i) the orange-brown patina on the marble surfaces of the Acropolis
in Athens and the Arch of Titus in Rome whose analyses have shown very high amounts of phosphates, and generally amino acids
from animal-skin glue or other protein binders; (ii) the phosphated patinas which also contain oxalates, found in 1996 on
Catalonian calcareous sandstones and in the calcareous dolomites of the Monastery of Silos, Spain, whose origin is either
the application of calcium caseinate, or egg yolk and animal glue; and (iii) the patinas with only oxalates found in some
of Verona's monuments (St Zeno) and Spanish sites as in the Monastery of Guadalupe and Cuenca cathedral, formed either by
the mineralization of algal filaments or by biological reactions yielding oxalate from yolk egg (added to stone as part of
preservative empirical treatments).
Methods In the winter of 2003, the West-Porch of Salisbury Cathedral received conservation works, but the old patina was not entirely
removed. This fact has allowed us to collect the samples for its study. The IR spectra were registered with a Golden Gate
ATR Mk II system using attenuated total reflectance Fourier transform infrared (ATR/FTIR) spectrometry. Mineral composition
was determined by XRD (Philips PW 1710 spectrometer with Cu tube), whereas major and trace elements analyses were performed
by XRF (Philips PW1480 PW). Microscopy examination was performed on a Leica M655 microscope. Phosphate, oxalate, calcium and
sulphate contents were analysed by usual chemical methods.
Results ATD-FTIR spectra of the Salisbury's patina exhibit peaks at 2361, 2341 and 671 cm–1 (assigned to phosphates); 3410, 1680,
1620, 1122 and 602 cm–1 (assigned to sulphates); and 1447/1437 and 876 cm–1 (attributed to carbonates). The little peaks at
1620 and 798 cm–1 could be assigned to oxalates. XRD and XRF have led to identify the carbonates, phosphates and sulphates
as pertaining to the species dolomite, hydroxyapatite and gypsum, respectively. Oxalates are detected only in small amounts
by chemical analyses but wewellite and weddellite have not been well identified. The interface between the patina and the
calcareous dolomite is very uneven and full of cavities in certain cases, but well-defined and rather smooth in other cases.
In accord with the very small amounts of the oxalates found, remnants of micro-organisms are not detected in the patinas.
Discussion The Salisbury's patina is a composite material formed by particulates and matrix constituents. Regarding the patina particulate,
e.g. animal bones, it is necessary to refer to the apatite phase composition. The bone mineral contains 4–8 wt % of carbonate
in animal body and its presence in the apatite phase is advantageous as it increases the mechanical strength. We think that
FTIR bands at around 1440 and 876 cm–1 arise from vibration of CO32– ions, but not necessarily from the limestone. They could
be attributed to carbonated hydroxyapatite through the substitution of groups PO43– for CO32– in the lattice of hydroxyapatite.
Concerning the matrix and also from the FTIR spectra, the absence of specific bands of the following species: proteins (3350–3225,
1660, 1550–1535, 1270–1230 and 620 cm–1), oils (1778, 1738 and 1051 cm–1), bee waxes (3000, 1470, 720–730 and 1700 cm–1) and
aged egg-yolk (2954, 2920, 2850, 1650, 1549, 1465 and 1240 cm–1) had led us to exclude these usual binders. On the other hand,
the amount of sulphates in the paste that covers the walls of the Salisbury's Cathedral is excessively high (above 20% in
weight) to consider it as a biotransformation product of calcium oxalate from fungal biofilms. Consequently, we must think
that the gypsum found in the samples has a man-made origin (it was deliberately added as part of a protective paste) and that
it is the matrix searched for. Thus, we deduce that the patina of Salisbury's Cathedral is a special stucco made mixing plaster
with powdered bone (the colour of the bones is the same that it exhibits in the patina), low quantities of an uncharacterized
binder (collagen, possibly) and water.
Conclusion We believe that the patina of the Salisbury's Cathedral is a variant of the Greco-Latin empirical protective treatment that
included bone as a hardening material. Nevertheless, we also think that the presence of the bones in the paste could be related
to an aesthetical intention: gaining a warm tone for the original stone through the ochre colour of the bones.
Recommendation and Perspective Our results have been an excuse to contribute to the controversy started at the 80's on the origin of orange-brown patinas
observed on stone surfaces of Greco-Latin and medieval monuments. There are two major theories on provenance: biological vs.
man-made. In Salisbury Cathedral, neither of them has been proven through scientific evidence as yet. Our opinion is that
Salisbury patina can be classified into the man-made group. 相似文献
714.
Sumita NM Mendes ME Macchione M Guimarães ET de Lichtenfels AJ de Lobo DJ Saldiva PH Saiki M 《Journal of the Air & Waste Management Association (1995)》2003,53(5):574-579
Tradescantia pallida cv. purpurea, a plant species widely employed for ornamentation in Brazil, has been successfully used for monitoring the genotoxicity of various agents by the micronucleus assay. To amplify knowledge about its suitability as a bioindicator species, its capacity for accumulating trace elements from urban air pollution was evaluated. T. pallida was rooted using standardized soil, and the vases were distributed in two highly polluted sites of the urban area of S?o Paulo, Brazil (Cerqueira Cesar and Congonhas districts), and in one unpolluted control site situated approximately 50 km from downtown S?o Paulo (in Caucaia do Alto). Approximately six months after exposure to pollutants, adult leaves of this plant were collected monthly for 12 months. The leaves were washed with deionized water, dried, and ground for analyses. Characterization of element levels was carried out by neutron activation analysis. Powdered samples and standards were irradiated at the IEA-R1 nuclear reactor for short and long periods, and concentrations of As, Ba, Br, Ca, Ce, Cl, Cr, Co, Fe, K, La, Mn, Na, Rb, Sb, Sc, Sr, Th, and Zn were determined. Analysis of variance applied to the results indicated that samples from polluted sites present the highest concentrations of Ba, Ce, Cr, Co, Fe, La, Sb, and Sc (p < 0.05). Discriminant analysis revealed that it was possible to distinguish the two polluted areas with a precision of 97.5%, based on the amount of pollutant elements measured in the plants at each site. The results indicated the potential use of T. pallida as an accumulator plant for air pollution biomonitoring. 相似文献
715.
Landslides into reservoirs and their impacts on banks 总被引:3,自引:0,他引:3
Rita Fernandes de Carvalho José Simão Antunes do Carmo 《Environmental Fluid Mechanics》2007,7(6):481-493
Mass wasting processes, like slope failures, on the margins of dam reservoirs, lakes, bays and oceans may generate large water
waves that can produce disasters due to flooding over the banks, run up along the shoreline and overtopping dam crests. Therefore,
the study of slope failures, the subsequent generation of impulse waves and their consequences are of paramount importance
for safety. In this paper the generation and propagation of water waves in reservoirs induced by landslides and their impact
on banks were investigated by means of a laboratory study carried out at University of Coimbra wave channel, in a flume measuring
12.0 m × 1.5 m × 1.0 m (L × H × W), where two banks with variable slope were placed. The study considered the sliding
of calcareous blocks over a sliding slope bank into the reservoir, the generation of impulse waves, their propagation in the
reservoir and their impact on the downstream bank. A number of waves were generated by different fallings of calcareous blocks,
considering different volumes, sliding slopes, initial positions and reservoir depths. All fallings were recorded by video-camera
and the results were processed afterwards to obtain the time history of the falling. The water surface variations due to transient
waves were measured at five gauges placed between the banks. The waves overtopping and breaking on the downstream bank were
also filmed using a video camera, and the hydrodynamic forces on this bank were also measured using four pressure transducers. 相似文献
716.
Tomás?Landete-CastillejosEmail author Christian?Gortázar Joaquin?Vicente Yolanda?Fierro Andres?Garcia Laureano?Gallego 《Behavioral ecology and sociobiology》2004,57(1):1-8
Several theories predict offspring biases towards males or females with increasing reproductive resources of the mother to maximize reproductive returns by offspring, or as a result of prohibitive cost of the most expensive sex for young mothers or those in poor condition. This study examines foetus sex of 221 harvested hinds in a food-supplemented game estate for 10 years, according to hind age class (yearlings, subadults or adults), precise age, body mass and condition, and jaw length. A logistic model showed that hinds had a greater probability of bearing a male foetus with increasing age class, but not with any other variable. The greatest bias was found in yearling hinds. After controlling for age class and mass, jaw length was smaller in pregnant compared to non-pregnant yearlings and subadults, which suggests a trade-off between reproduction and growth. The bias towards females in yearlings increased as gestation proceeded, which suggests that the bias might be a result of selective abortion of male foetuses. Although results do not exclude an investment in males to increase number of grand-offspring, they suggest that young hinds may produce daughters as a trade-off between low energetic-cost offspring and their need to grow.Communicated by S. Krackow 相似文献
717.
Maria do Socorro S. Pereira Eduardo Winter Jose Roberto Guimarães Susanne Rath Anne Hélène Fostier 《Environmental Chemistry Letters》2007,5(3):137-141
Here, we show a fast and sensitive method for the determination of inorganic arsenic in natural waters using differential
pulse cathodic stripping voltammetry. All the arsenite determinations were done in 2.0 mol L−1 HCl + 3.15 × 10−4 mol L−1 Cu(II) supporting electrolyte. 1 × 10−3 mol L−1 sodium thiosulphate was used as As(V) reducing agent. The detection limit was 0.5 μg L−1 for both species. The method has been applied to water samples collected in an arsenic-contaminated region of Brazil, in
particular, to verify the efficiency of the solar oxidation and removal of arsenic process applied to these waters. 相似文献
718.
Georgia Carvalho Paulo Moutinho Daniel Nepstad Luciano Mattos Márcio Santilli 《Environment, Development and Sustainability》2004,6(1-2):163-174
Amazonia contains more carbon (C) than a decade of global, human-induced CO2 emissions (60–80 billion tons). This C is gradually being released to the atmosphere through deforestation. Projected increases in Amazon deforestation associated with investments in road paving and other types of infra-structure may increase these C emissions. An increase of 25–40% in Amazon deforestation due to projected road paving could counterbalance nearly half of the reductions in C emissions that would be achieved if the Kyoto Protocol were implemented. Forecasted emission increases could be curtailed if development strategies aimed at controlling frontier expansion and creating economic alternatives were implemented. Given ancillary benefits and relative low costs, reducing deforestation in Amazonia and other tropical areas could be an attractive option for climate mitigation. Projects that help contain deforestation and reduce frontier expansion can play an important role in climate change mitigation but currently are not allowed as an abatement strategy under the climate regime. Creating incentives for forest conservation and decreased deforestation can be a unique opportunity for both forest conservation and climate mitigation. 相似文献
719.
Ricardo M. Trigo Alexandre M. Ramos Paulo J. Nogueira Filipe D. Santos Ricardo Garcia-Herrera Célia Gouveia Fátima E. Santo 《Environmental Science & Policy》2009,12(7):844-854
This paper analyses the impact of the 2003 European heatwave on excessive human mortality in Portugal, a country that presents a relatively high level of exposure to heatwave events. A total of 2399 excessive deaths are estimated in continental Portugal, which implies an increase of 58% over the expected deaths. When these values are split by gender, it is seen that women increase (79%), was considerably higher than that recorded for men (41%). The increment of mortality due to this heatwave was detected for all the 18 districts of the country, but its magnitude was significantly higher in the inner districts close to the Spanish border. When we split by gender all districts reveal significant mortality increments for women, while the impact in men's excess deaths is not significant over 3 districts. Several temperature derived indices were used and evaluated in their capacity to explain, at the regional level, the excessive mortality (ratio between observed and expected deaths) by gender. It is shown that the best relationship is found for the total exceedance of extreme days, an index combining the length of the heatwave and its intensity. Both variables hold a linear relationship with r = 0.79 for women and a poorer adjustment (r = 0.50) for men. Additionally, availability of mortality data split by age also allowed obtaining detailed information on the structure of the population in risk, namely by showing that statistically significant increments are concentrated in the last three age classes (45–64, 65–74 and 75 or more). The use of air conditioning systems in some Portuguese hospitals had a major impact on the decrease (up to 40%) in excessive mortality values. A finer approach is relevant for prevention strategies, since it allows to identify better the target population of any preventive strategy regional and national authorities may be interested to implement. 相似文献
720.
Photodynamic inactivation (PDI) is extensively used to inactivate different type of pathogens through the use of photosensitizers (PS). Curcumin has been identified as an excellent natural photosensitizer with some potential applications in the food industry. The aim of this study was to assess the antiviral activity of photoactivated curcumin on norovirus surrogates, feline calicivirus (FCV), and murine norovirus (MNV). Initially, different concentrations of curcumin (13.5–1358 µM) were individually mixed with each virus at titers of ca. 6–7 log TCID50/ml and photoactivated by LED blue light with light dose of 3?J/cm2. Results showed that photoactivated curcumin at 50 µg/mL reduced FCV titers by almost 5 log after incubation at 37 °C for 30 min. Lower antiviral activity (0.73 log TCID50/mL reduction) was reported for MNV. At room temperature, curcumin at 5 µg/mL reduced FCV titers by 1.75 log TCID50/mL. These results represent a step forward in improving food safety using photoactivated curcumin as an alternative natural additive to reduce viral contamination. 相似文献