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401.
402.
Globally, urban growth will add 1.5 billion people to cities by 2030, making the difficult task of urban water provisions
even more challenging. In this article, we develop a conceptual framework of urban water provision as composed of three axes:
water availability, water quality, and water delivery. For each axis, we calculate quantitative proxy measures for all cities
with more than 50,000 residents, and then briefly discuss the strategies cities are using in response if they are deficient
on one of the axes. We show that 523 million people are in cities where water availability may be an issue, 890 million people
are in cities where water quality may be an issue, and 1.3 billion people are in cities where water delivery may be an issue.
Tapping into groundwater is a widespread response, regardless of the management challenge, with many cities unsustainably
using this resource. The strategies used by cities deficient on the water delivery axis are different than for cities deficient
on the water quantity or water quality axis, as lack of financial resources pushes cities toward a different and potentially
less effective set of strategies. 相似文献
403.
Salting-out phenomenon and 1-octanol/water partition coefficient of metalaxyl pesticide 总被引:1,自引:0,他引:1
In this paper, we present the effect of inorganic cations such as Na+, K+, Ca2+, Mg2+ on the salting-out phenomenon of metalaxyl from pure water to aqueous salt solutions. Moreover the 1-octanol/water partition coefficient in pure water is presented. To accomplish this, aqueous solubility of metalaxyl was determined in pure water, in different salt solution (NaCl, KCl, CaCl2 and MgCl2), and at different concentration level ranging from 0.01 to 1.5 M. The 1-octanol/water partition coefficient was determined using the static shake-flask method. Solubility was determined using dynamic saturation method for pure water in the range of 298.15-325.15 K and at 298.15 K for different salt solutions. The solubility value in pure water for studied interval was found constant (m = 3.118 × 10−2 mol kg−1).Solubility values were used to calculate the standard molar Gibbs free energy of dissolution (ΔsolG°) and transfer (ΔtrG°) at 298.15 K. The values of ΔtrG° from pure to all studied aqueous salt solutions did not exceed 2 kJ mol−1, the value of ΔsolG° of dissolution is 18.5 ±0.72 kJ mol−1. The 1-octanol/water partition coefficient in pure water log Ko/w is equal to 1.69. The obtained results confirm the classification of the neutral metalaxyl as a slightly hydrophobic molecule. 相似文献
404.
Otones V Álvarez-Ayuso E García-Sánchez A Santa Regina I Murciego A 《Environmental pollution (Barking, Essex : 1987)》2011,159(10):2637-2647
A mining area affected by the abandoned exploitation of an arsenical tungsten deposit was studied in order to assess its arsenic pollution level and the feasibility of native plants for being used in phytoremediation approaches. Soil and plant samples were collected at different distances from the polluting sources and analysed for their As content and distribution. Critical soil total concentrations of As were found, with values in the range 70-5330 mg kg−1 in the uppermost layer. The plant community develops As tolerance by exclusion strategies. Of the plant species growing in the most polluted site, the shrubs Salix atrocinerea Brot. and Genista scorpius (L.) DC. exhibit the lowest bioaccumulation factor (BF) values for their aerial parts, suggesting their suitability to be used with revegetation purposes. The species Scirpus holoschoenus L. highlights for its important potential to stabilise As at root level, accumulating As contents up to 3164 mg kg−1. 相似文献
405.
Jofré MB Antón RI Caviedes-Vidal E 《Environmental science and pollution research international》2011,19(7):2889-2897
Purpose
Heavy metals have been detected in water and sediments from the Embalse La Florida, an artificial lake in the arid region of San Luis province, Argentina, representing one of the few sources of permanent water for reproduction of native anuran species. This study assesses lead (Pb) and cadmium (Cd) concentrations in the anuran species found in this water reservoir as well as differences between compounds, species and sites of collection.Methods
Adult anuran amphibians were collected on the north and south shores of the Embalse La Florida and Pb and Cd concentrations were measured in whole body homogenates digested using wet ashing techniques.Results
All individuals of the six species assayed had detectable levels of Pb and Cd that ranged from 1.19 to 5.57 ??g/g dry mass and from 1.09 to 6.86 ??g/g dry mass, respectively. Anuran amphibians collected in the more contaminated south shore accumulated 21% more Cd and 40% more Pb than individuals from the less altered north shore. Cd and Pb accumulation was not significantly correlated with the concentration in water at the site of collection.Conclusions
Amphibians of the Embalse La Florida accumulate Cd and Pb. Between and within species, differences were detected in Cd and Pb concentrations. Differences in metal concentrations between species, metals, and individuals collected on shores of the Embalse La Florida with different contamination, were detected. Therefore, it is crucial to implement adequate policies to protect amphibians from the accelerated urban development experienced in this location. 相似文献406.
J.M. Santos I. Mavroidis N.C. Reis Jr. E.C. Pagel 《Atmospheric environment (Oxford, England : 1994)》2011,45(36):6534-6545
Tracer gas was released upwind of a two-compartment complex shaped building under unstable atmospheric conditions. The mean wind direction was normal to or at 45° to the long face of the building. The general patterns of concentration distribution on the building external walls and inside the building were analysed and the influence of natural and mechanical ventilation on indoor concentration distributions was discussed. Mean concentration levels, as well as the concentration fluctuation intensity, were higher on the windward walls of the building, although concentration levels varied along each wall. Concentration fluctuations measured inside the building were lower than those measured outside. Inside the two compartments of the building, the time series of concentrations had a similar general behaviour; however, gas concentrations took approximately 1.5 times longer to reach the mean maximum concentration value at the downwind compartment 02 while they also decreased more rapidly in the upwind compartment 01 after the source was turned off. The highest indoor concentration and concentration fluctuation values were observed at the detectors located close to the windward walls, especially when the building windows were open. Experiments with and without natural ventilation suggested that infiltration and exfiltration of contaminants is much faster when the building windows are open, resulting to higher indoor concentration levels. Furthermore, mechanical ventilation tends to homogenize concentrations and suppress concentration fluctuations, leading to lower maximum concentration values. 相似文献
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