Regional impervious surface estimation: an urban heat island application

This paper describes a GIS-based estimation method that can be used to forecast future amounts of impervious surface as a mitigation measure for urban heat island effect in a metropolitan region. The method is unique because it employs a regression model that links the existing amount of impervious surface to population and employment at the census tract level. This approach provides a means to forecast future amounts of impervious surface based on projected population and employment. The method also includes a detailed analysis of high-resolution aerial photography to divide impervious surfaces into different categories. Subdividing impervious surfaces is necessary to evaluate potential urban heat island mitigation policies for different types of impervious surface. The analysis here shows that the impervious surface in the metropolitan Atlanta region will increase to 2638 km2 2. “The Albedo is defined as the hemispherical reflectivity averaged over the solar spectrum. A perfect reflector has a = 1, and a perfect absorber has a = 0” (Pomerantz et al. 1999 Pomerantz, M. 1999. Reflective surfaces for cooler buildings and cities. Philosophical magazine B, 79: 1457–1476. [Taylor & Francis Online], [Web of Science ®] [Google Scholar], p. 1458). View all notes in 2030, an increase of 45% from 2000. The most common type of impervious surface is dark-coloured pavement. Within this study area, the analyses showed that two-thirds of impervious surfaces are dark. Replacing dark pavement with light pavement materials, therefore, represents an important opportunity to mitigate the urban heat island effect in the Atlanta region.     

Americium,plutonium and uranium contamination and speciation in well waters,streams and atomic lakes in the Sarzhal region of the Semipalatinsk Nuclear Test Site,Kazakhstan

New data are reported on the concentrations, isotopic composition and speciation of americium, plutonium and uranium in surface and ground waters in the Sarzhal region of the Semipalatinsk Test Site, and an adjacent area including the settlement of Sarzhal. The data relate to filtered water and suspended particulate from (a) streams originating in the Degelen Mountains, (b) the Tel′kem 1 and Tel′kem 2 atomic craters, and (c) wells on farms located within the study area and at Sarzhal. The measurements show that ²⁴¹Am, ^239,240Pu and ²³⁸U concentrations in well waters within the study area are in the range 0.04–87 mBq dm⁻³, 0.7–99 mBq dm⁻³, and 74–213 mBq dm⁻³, respectively, and for ²⁴¹Am and ^239,240Pu are elevated above the levels expected solely on the basis of global fallout. Concentrations in streams sourced in the Degelen Mountains are similar, while concentrations in the two water-filled atomic craters are somewhat higher. Suspended particulate concentrations in well waters vary considerably, though median values are very low, at 0.01 mBq dm⁻³, 0.08 mBq dm⁻³ and 0.32 mBq dm⁻³ for ²⁴¹Am, ^239,240Pu and ²³⁸U, respectively. The ²³⁵U/²³⁸U isotopic ratio in almost all well and stream waters is slightly elevated above the ‘best estimate’ value for natural uranium worldwide, suggesting that some of the uranium in these waters is of test-site provenance. Redox analysis shows that on average most of the plutonium present in the microfiltered fraction of these waters is in a chemically reduced form (mean 69%; 95% confidence interval 53–85%). In the case of the atomic craters, the proportion is even higher. As expected, all of the americium present appears to be in a reduced form. Calculations suggest that annual committed effective doses to individual adults arising from the daily ingestion of these well waters are in the range 11–42 μSv (mean 21 μSv). Presently, the ground water feeding these wells would not appear to be contaminated with radioactivity from past underground testing in the Degelen Mountains or from the Tel′kem explosions.     

C60 fullerene: a powerful antioxidant or a damaging agent? The importance of an in-depth material characterization prior to toxicity assays

Since the discovery of fullerenes in 1985, these carbon nanospheres have attracted attention regarding their physico/chemical properties. Despite little knowledge about their impact on the environment and human health, the production of fullerenes has already reached an industrial scale. However, the toxicity of C₆₀ is still controversially discussed.The aim of this study was to clarify the biological effects of tetrahydrofuran (THF) suspended C₆₀ fullerene in comparison to water stirred C₆₀ fullerene suspensions. Beyond that, we analyzed the effects on the Crustacea Daphnia magna an indicator for ecotoxicological effects and the human lung epithelial cell line A549 as a simplified model for the respiratory tract.We could demonstrate that water-soluble side products which were formed in THF nC₆₀ suspension were responsible for the observed acute toxic effects, whereas fullerenes themselves had no negative effect regardless of the preparative route on either A549 cell in vitro or D. magna in vivo.     

Ecogenetic features and functions of solods in transural forest-steppes (within Sverdlovsk Oblast)

Specific ecogenetic features of solods in the forest-steppe zone has been studied, and the role of biotic and abiotic factors of soil formation has been estimated. Differentiation of soil horizons with respect to the physical clay fraction accounts for specific features of their moistening, which is reflected in the ratio of strongly and weakly crystallized forms of iron. Periodic changes in redox conditions results in iron segregation, and a high content of fulvic acids accounts for its eluvial migration. These processes are controlled by soil geochemical barriers.     

Use and knowledge of fuelwood in three rural caatinga (dryland) communities in NE Brazil

The woody species known, used, and preferred as fuelwood were examined in three rural communities within the county of Soledade, Paraíba State, NE Brazil. Ethnobotanical information was collected using semi-structured interviews with more than 90% of the local households (55 adult residents; 31 women, and 24 males). The interviewees cited 36 plant species as fuelwoods, distributed among 30 genera and 15 families, in addition to two unidentified plants. The plant families represented by the largest numbers of species were Euphorbiaceae, Anacardiaceae, Mimosaceae, Caesalpiniaceae, Sapotaceae, and Fabaceae. The species Caesalpinia pyramidalis Tul. (“catingueira”) was cited with the greatest frequency in all three communities. Within the communities we found significant differences on the number of plants cited and actually used (p < 0.05), indicating that the residents knew more fuelwood species than they effectively harvest. The different distances from the communities to the urban centers were not related to differences on the use or the size of the stocks of fuelwood. Additionally, the study revealed that the communities examined still maintain a significant knowledge of the use of energy-providing plants in spite of the widespread use of liquefied petroleum gas (LPG). Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Specific features of early stages of progressive succession in an anthropogenic landscape: An example from southeastern Belarus

Specific features of progressive succession in the vegetation of anthropogenically transformed landscapes in southeastern Belarus have been studied in permanent test plots. Using phytoindication scales proposed by Ellenberg (1974) and Tsyganov (1983), trends of changes in ecological conditions in the first years of succession have been revealed.     

Postfire succession in a forest of the cryolithozone: The example of central Yakutia

The results of studies on postfire succession in larch forests of the permafrost zone are discussed. The main directions of successional processes in burned-out areas of different ages are described. It has been shown that secondary pyrogenic successions in larch forests follow the scheme of rapid regeneration without tree species replacement and the model of succession tolerance. Groups of plant species with different life strategies and indicator species characterizing different stages of the overgrowing of burned-out areas have been identified.     

Converging hydrostatic and hydromechanic concepts of preferential flow definitions

The boundary between preferential flow and Richards-type flow is a priori set at a volumetric soil water content θ at which soil water diffusivity D (θ) = η (= 10^− 6 m² s^− 1), where η is the kinematic viscosity. First we estimated with a hydrostatic approach from soil water retention curves the boundary, θ^K, between the structural pore domain, in which preferential flow occurs, and the matrix pore domain, in which Richards-type flow occurs. We then compared θ^K with θ that was derived from the respective soil hydrological property functions of same soil sample. Second, from in situ investigations we determined 96 values of θ^G as the terminal soil water contents that established themselves when the corresponding water-content waves of preferential flow have practically ceased. We compared the frequency distribution of θ^G with the one of θ that was calculated from the respective soil hydrological property functions of 32 soil samples that were determined with pressure plate apparatuses in the laboratory. There is support of the notion that θ^K ≈ θ^G ≈ θ, thus indicating the potential of θ to explain more generally what constitutes preferential flow. However, the support is assessed as working hypothesis on which to base further research rather than a procedure to a clear-cut identification of preferential flow and associated flow paths.     

Degassing of H/He, CFCs and SF6 by denitrification: Measurements and two-phase transport simulations

The production of N₂ gas by denitrification may lead to the appearance of a gas phase below the water table prohibiting the conservative transport of tracer gases required for groundwater dating. We used a two-phase flow and transport model (STOMP) to study the reliability of ³H/³He, CFCs and SF₆ as groundwater age tracers under agricultural land where denitrification causes degassing. We were able to reproduce the amount of degassing (R² = 69%), as well as the ³H (R² = 79%) and ³He (R² = 76%) concentrations observed in a ³H/³He data set using simple 2D models. We found that the TDG correction of the ³H/³He age overestimated the control ³He/³He age by 2.1 years, due to the accumulation of ³He in the gas phase. The total uncertainty of degassed ³H/³He ages of 6 years (± 2 σ) is due to the correction of degassed ³He using the TDG method, but also due to the travel time in the unsaturated zone and the diffusion of bomb peak ³He. CFCs appear to be subject to significant degradation in anoxic groundwater and SF₆ is highly susceptible to degassing. We conclude that ³H/³He is the most reliable method to date degassed groundwater and that two-phase flow models such as STOMP are useful tools to assist in the interpretation of degassed groundwater age tracer data.