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Costa EA Campos VP da Silva Filho LC Greven HA 《Journal of environmental management》2009,90(2):1060-1068
In recent years, growing interest has focused on determining the performance of materials and evaluating the service life of structures exposed to various environmental forces. In this context, the determination of the aggressive potential of marine salts on mortars used as external renders is critical. The present study aimed to evaluate the spatial distribution of marine salts relative to distance from the sea. This was done by monitoring the deposition rate of chlorides and sulfates in wet candle sensors, located at nine stations scattered around the Metropolitan Region of Salvador, state of Bahia, Brazil. The study also determined the effectiveness of water-soluble salts at penetrating three different types of mortars of varying cement content via deposition and diffusion. The methodology employed enabled an evaluation of the efficiency of the monitoring sensors' measurement of the aggressiveness potential of local marine aerosol, and determination of the comparative performance of the three mortars tested, from the standpoint of resistance to salt penetration. The type and amount of salts captured both in solution and in powder samples extracted from the mortars were determined by ion chromatography. The analysis of the various types of mortars tested indicated which types are more resistant to the aggressive potential of the region's marine aerosol and the distance from the shore where local buildings are liable to be most strongly affected. 相似文献
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The atmospheric chemical composition is affected by the interaction mechanisms among gases and particulate matter through
a wide range of chemical reactions that can occur with the aid of particulate matter (e.g. particles act as reacting or absorbing
surfaces) or be influenced by the presence of particulate matter in the atmosphere (photochemical reactions). Physical and
chemical processes are also bonded in an interactive way that often leads to the influence of the radiation budget, cloud
physics and the warming or cooling of the lower atmospheric levels. The Euro-Mediterranean region is a key-sensitive area
due to the unique climatic and air quality characteristics associated with the regional climatic patterns, geomorphology (land
and water contrast) and coexistence of pollutants from different origin. Focusing on this region, the gas-aerosol interactions
are studied using state-of-the-art atmospheric and chemical transport modeling tools following the necessary development in
the chemical transport model CAMx. Sensitivity and large-scale simulations have shown significant responses of the modeling
system to the inclusion of natural species emissions, the direct shading effect of dust particles on photochemical processes
and the formation of new types of aerosols through heterogeneous uptake of gases on dust particles. Including such interactions
in the chemical transport model often led to the improvement of the model performance compared with available measurements
in the region. 相似文献
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Meritxell Aulinas Maite Garcia-Valles Domingo Gimeno Jose Luis Fernandez-Turiel Flavia Ruggieri Montserrat Pugès 《Environmental science and pollution research international》2009,16(4):443-452
Background, aim, and scope The first step in the restoration of a medieval stained glass window is the evaluation of its degree of degradation. This
implies the study of the chemical composition of the stained glass as well as the new mineral phases developed on its surface
(patinas). Patinas are clearly related to glass composition, time, environmental conditions, microenvironments developed in
local zones, bioactivity, physical and chemical factors, etc. This study was carried out on patinas developed in selected
Na-rich stained glass of the Santa Maria de Pedralbes Monastery (Barcelona, Spain). The location of this monument in the city
(about 5 km from the shoreline and close to the Collserola hill flank) helped to determine the environmental conditions in
which patinas developed. The aim of our study was to characterize the patinas formed on the surface of the selected glass
of this monastery in order to understand the role of the chemical composition of the original glass (Na-rich) as well as the
environmental conditions in which they developed.
Materials and methods Powdered samples of two different color-type patinas (ochre-orange and brownish) were collected in the external and internal
parts of the stained glass windows of the Prebystery and Chapter House of the Pedralbes Monastery by using a precision (odontological)
drill. These patinas were subsequently analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR).
Results XRD analyses evidenced the presence of sulfates (gypsum and thenardite), calcite, Ca-oxalates (whewellite and weddellite),
and quartz forming part of the patinas. Although these mineral phases can be found in both color-type patinas, whewellite
and thenardite are more common in the ochre-orange patinas. The results obtained were validated by the FTIR measurements.
It has been observed, when thenardite is present, that gypsum occurs as traces. Thenardite is in most of the cases associated
with whewellite and mainly occurs in the internal parts of the glass. In contrast, weddellite is limited to the absence of
thenardite and whewellite and to the external parts of the stained glass. Quartz is present in all the patinas independent
of their location and color. Calcite also occurs in many samples. It appears in both color-type patinas and, in some cases,
is associated to the presence of weddellite but not to whewellite and/or thenardite.
Discussion Glass composition together with environmental conditions and location of the patinas (internal or external parts of the stained
glass window), as well as the provenance of the glass within the monastery, are the main factors that define the development
of the new mineral phases. Moreover, the action of microorganisms, when present, can also strongly influence the development
of some mineral phases. For example, the formation of calcite in the external parts of the stained glass (associated with
the presence of oxalates) is related to the action of microorganisms. When calcite is formed in the internal parts of the
glass and it is not associated with the presence of Ca-oxalates, an inorganic origin can be invoked. The presence of weddellite
requires a very humid microenvironment with very little exposure to sunlight. In fact, this mineral phase has only been observed
in the external parts of some glass located in the humid and shady side of the monastery. Whewellite (which only appears in
the internal parts) needs a low degree of relative humidity. It has been observed that sulfur precipitating in basically one
mineral phase (thenardite or gypsum) depends on the microenvironmental conditions of the moment and the glass composition.
When thenardite occurs, it can be maintained that the original glass is of Na composition. The occurrence of quartz in all
samples is interpreted as being due to the deposition of atmospheric particulate matter. The color of the patinas can be originated
by different processes (presence of carotenes, organic pigmentation, atmospheric contamination, etc.).
Conclusions In the case of moderately weathered stained glass windows, the combination of XRD and FTIR techniques is very useful to obtain
a fast preliminary evaluation of the degree of weathering of a stained glass window. The presence of specific mineral phases
in the patina (e.g., thenardite) confirms the Na composition of the original stained glass. This is important since Na-rich
glass underwent a lesser degree of weathering than K- or K-Ca-rich glass. However, their absence cannot preclude other possibilities.
It has been extensively evidenced through time that environmental conditions play an important role on the formation of the
different mineral phases which form part of the patinas.
Recommendations and perspectives The first step in the restoration of a stained glass window is the evaluation of the degree of deterioration of the glass.
This evaluation includes a chemical analysis of the glass as well as a characterization of the patinas developed on their
surfaces. The obtained results will be essential in order to define the best restoration practices to be followed. 相似文献
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Rainwater samples were collected in the western sector of Mexico City (MC) and at Rancho Viejo (RV), 80 km west-south-west of MC, from 2001 to 2005, and Orizaba City (OC), about 90 km from the Gulf of Mexico, where rainwater collections were only possible on some weekends in 2001. Rainwater samples were treated in the field, and analysed by fluorescence at the laboratory. The volume-weighted mean concentration (VWMC) of H2O2 was 13.2 μM at RV, and 11.2 μM in MC, for the period 2001–2005. The highest VWMC was observed in OC (21.6 μM). The VWMCs for each year were 9.5, 14.4, 11.5, 16.7, and 14.3 μM at RV, and 12.2, 12.2, 14.3, 11.8, and 9.9 μM in MC, for 2001–2005, respectively. Hydrogen peroxide in rainwater correlated significantly and negatively with sulfate in both MC and RV, but not, however, in OC. This study confirmed that H2O2 concentration in rainwater is controlled by a complex combination of rain intensity, washout processes and in-cloud formation of H2O2, acting simultaneously. This was suggested by the fact that rain intensity seemed to predominate in certain rain fractions of a rain event, while washout processes seemed to predominate in other fractions of the same rain event. 相似文献
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Chlorophenols are an important class of persistent environmental contaminants and have been implicated in a range of adverse health effects, including cancer. They are readily conjugated and excreted as the corresponding glucuronides and sulfates in the urine of humans and other species. Here we report the synthesis and characterization of a series of ten chlorophenol sulfates by sulfation of the corresponding chlorophenols with 2,2,2-trichloroethyl (TCE) chlorosulfate using N,N-dimethylaminopyridine (DMAP) as base. Deprotection of the chlorophenol diesters with zinc powder/ammonium formate yielded the respective chlorophenol sulfate ammonium salts in good yield. The molecular structure of three TCE-protected chlorophenol sulfate diesters and one chlorophenol sulfate monoester were confirmed by X-ray crystal structure analysis. The chlorophenol sulfates were stable for several months if stored at −20 °C and, thus, are useful for future toxicological, environmental and human biomonitoring studies. 相似文献
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