This study assessed the state of waters in Belgrade regarding pollution with musk compounds as the target contaminants. Eleven of these compounds were alicyclic, two were macrocyclic, and one was polycyclic. Solid-phase microextraction was used for the isolation of these compounds from waste, surface and underground waters and from processed water prepared for drinking, while comprehensive orthogonal two-dimensional gas chromatography with mass spectrometry was used as the final analytical method. In wastewater samples, galaxolide was detected in concentrations of 1.13 and 0.40 μg/L, while in the Sava River and underground water its concentrations were 0.09 and 0.038 μg/L. The lowest concentrations of the investigated musk compounds were detected in underground water samples, indicating that this is the cleanest water of all the analyzed sources with respect to musk compounds. Comparing the results of musk compound concentrations determined in surface river water samples and clean river water samples utilized for drinking, a lower concentration of these compounds was detected in the clean river water samples. The majority of musk compounds were found in waters utilized for drinking. Based on the concentration values, we conclude that the analyzed waters are moderately polluted with these compounds. 相似文献
Katabatic flows over high-latitude long glaciers experience the Coriolis force. A sloped atmospheric boundary-layer (ABL)
flow is addressed which partly diffuses upwards, and hence, becomes progressively less local. We present the analytical and
numerical solutions for (U ,V, θ) depending on (z, t) in the katabatic flow, where U and V are the downslope and cross-slope wind components and θ is the potential temperature perturbation. A Prandtl model that accounts for the Coriolis effect, via f, does not approach a steady state, because V diffuses upwards in time; the rest, i.e., (U, θ), are similar to that in the classic Prandtl model. The V component behaves in a similar manner as the solution to the 1st Stokes (but inhomogeneous) problem. A WKB approach to the
problem of the sloped ABL winds is outlined in the light of a modified Ekman-Prandtl model with gradually varying eddy diffusivity
K(z). Ideas for parameterizing these high-latitude persistent flows in climate models are revealed.
After Wentzel, Kramers and Brillouin, who popularized the method in theoretical physics. 相似文献
Among the numerous factors that trigger landslide events, the anthropogenic impact caused by inadequate planning and faulty land use in urban areas is increasing. The Zemun settlement on the northern outskirts of Belgrade has experienced a number of landslides in the last three decades, endangering buildings and roads, and claiming human lives, particularly in the case of the 2010/2011 landslides. Selected meteorological parameters were used to calculate rainfall erosivity indices such as Precipitation Concentration Index and Modified Fournier Index over the period 1991–2015. Drought indices, Lang aridity index and Palfai Drought Index were calculated as well. Mann–Kendall trend test was applied to identify potential rising and/or declining trends both in meteorological parameters and calculated indices. Trend analysis of the annual and seasonal scales yielded a statistically significant trend in the spring time series. Stable arid and pronounced drought conditions were recorded. The modified Fournier index based on monthly mean values yields moderate aggressiveness, with several extreme values indicating very high erosivity classes, especially for 2010/2011. The geological substrate is predominantly loess and hence highly susceptible to erosion and slope failure when climatological conditions are suitable. Accelerated urbanization at the end of the last century reduced vegetation cover, intensified pressure on the vertical loess slope, and lacked suitable rain drainage systems so that surface-water runoff was directed into the porous loess, thereby endangering slope stability. We proposed a geomorphic model to describe the nature of the erosional processes on the loess cliffs of the Zemun loess plateau. Results from this study have implications for mitigation strategies. 相似文献
Research on policy support or public acceptability of climate change policies is proliferating. There is, however, a great diversity in how these evaluative responses have been defined, operationalized, and measured across studies. In order to shed some light on this subject, we reviewed 118 studies published over the last 15 years aiming at measurement of policy acceptability, acceptance, support, and other responses to climate change mitigation policies. We found that conceptual vagueness and weak theoretical embedding are pervasive in the field, which leads to uncertainty over what is being measured, ambiguity of policy recommendations, and difficulties in comparing empirical results. In response, we propose a construct of policy attitudes as an overarching concept comprising the diversity of measures and constructs already in use. The purpose of the construct is to serve as a common basis for operationalization and survey design. In order to inform policy makers, researchers should be clear in how they formulate surveys with a focus on questions of importance to research and policy-making.
Key policy insights
Acceptability, acceptance, and support are defined as distinct and possibly empirically distinguishable classes of responses evaluating a policy proposal. These responses are expressions of underlying policy attitudes.
People may respond to policies in other ways as well, including lack of interest.
There is no popularity threshold for a policy to be safe to implement, but instead it is a matter of identifying the conditions of policy support or other responses.
Results obtained using different measures of mitigation policy attitudes vary widely with respect to the characteristics of the policy in question and the measured response. Thus, great care must be taken when designing surveys and interpreting their results.
This study proposes a framework to investigate the roles of urban spaces in connecting social contacts (i.e., “friends”). The framework is applied to a Call Detail Record (CDR) dataset collected in Singapore. First, a comparative analysis is performed to understand how friends share urban space differently from random people. Then, we derive two metrics to quantify the “bonding” and “bridging” capabilities of places in the city. The two metrics reflect the potential of a place in connecting friends and random people (e.g., chance encounters), respectively. Finally, we examine the temporal signature of the places’ bonding capabilities, and associate the results with various types of Points of Interest (POIs). We find that: (1) friends are more likely to share urban space than random people, and they also share more locations; (2) a place could play different roles in connecting friends vs. random people, and the relationship (between bonding and bridging) varies depending on the time and type of a day (weekdays vs. weekends); (3) the temporal signature of bonding capability is strongly related to the semantics of a place; (4) certain POI types (e.g., shopping malls) tend to have a much higher impact on bonding capability than others (e.g., sports centers). 相似文献