Commuting patterns of Czech households exposed to flood risk from the Bečva river

Using unique data collected in October–December 2012 we estimate the link between commuting for work and level of individual exposure to floods. We find that commuters on average have higher earnings than non-commuters. Individuals affected by one flood commute by 11.2% more than unaffected individuals. We conjecture that the increase is linked to intentions to cover flood-related losses, decrease households' vulnerability to flood risk or out-migrate from the risk areas. Individuals affected by at least two floods are by 20.2% less likely to commute relative to those unaffected. We explain this non-linear effect by the fact that many households out-migrate after the first flood. Stayers commute less, because they are different from non-stayers in some underlying characteristics related to education, employment and family circumstances, which strongly affect commuting behaviour. We further find that in a commuting family an individual is by 53.8% more likely to commence commuting relative to a non-commuting family. Choice of commuting destination is often similar to that of other family members.     

Gas chromatography with atomic absorption detection for the determination of alkyl selenide compounds in the breath of mice after administration of different selenium compounds

Quantitative determination of dimethylselenide and dimethyldiselenide in the breath of mice after addition of different selenium compounds to the drinking water is described. Breath samples are collected with a cryogenic trap and analyzed by gas chromatography with atomic absorption spectrometric detection. Detection limits down to 0.2 ng/100 g body weight are obtained.

The pulmonary excretion of selenium metabolites after oral administration via drinking water or after intraperitoneal injection appears to be negligible. The bioconversion of the different selenium species is discussed.     

A model based on molecular structure descriptors for predicting mutagenicity of organic compounds

A model predictive of the potential mutagenicity of organic compounds was devised by relating mutagenicity data obtained in the Ames reversion test to molecular structure parameters describing their hydrophobic, topological, steric and electronic properties. These included second order valence molecular connectivity index, parachor, molar refraction and polarizability of electrons. A classification rule was calculated, by means of discriminant analysis, using a training set of 117 compounds of various chemical classes. There was agreement between experimental data and theoretical expectations for the majority of compounds (70.9%), with homogeneous figures among the different chemical classes under scrutiny. An exception was represented by halogenated aliphatics with up to 3 C atoms, the mutagenicity of which was poorly predicted by the structural analysis model.     

Organic pollutants in snow of urban and rural Russia and Finland

To check the effect of possible deposition of organic contaminants in northern regions of the Earth due to atmospheric transport snow samples were collected in early March in 6 places in Russia and 4 in Finland including arctic territories. GC‐MS was used as an analytical tool to identify and quantify individual organic compounds belonging to the various classes. As a result more than 250 compounds were detected. The possible presence of more than 100 other priority pollutants from the US EPA list was also screened.     

Uptake and transformation of perchlorate by vascular plants

Phytoremediation is a promising new method that uses green plants to cleanse soil and water contaminated with organic or inorganic pollutants. In this study, the uptake and transformation of sodium perchlorate (NaClO₄) using four vascular plant species were examined in batch experiments. The species include two trees, cabbage gum (Eucalyptus amplifolia) and eastern cottonwood (Populus deltoides), a herbaceous wetland plant, perennial glasswort (Salicornia virginica), and a herbaceous aquatic plant, waterweed (Elodea canadensis). Perchlorate was depleted from solution in the presence of all but one species (waterweed). Depletion was calculated as a first‐order kinetics reaction with k values in the range of 0–0.013 per day and accumulation of perchlorate was between 3.2 and 3138 mg/kg. Perchlorate and transformation metabolites (chlorate, chlorite, chloride) were observed in all plant tissues (e.g., roots, stems, leaves) analyzed. Results suggest that significant influences on perchlorate uptake include: (1) plant species present, (2) concentration of perchlorate, (3) sand versus hydroponic treatments, (4) the presence or absence of plant nutrients or competing ions, (5) stage of plant maturity.     

Analytical studies on the pollution of argeş river

Using two analytical techniques (ICP‐AES and ASV) the heavy metal pollution of Arge? River was studied. These techniques are characterized by similar analytical performances.

The samples were collected from 13 sites starting from Capra Lake (altitude 2241 m) and finishing at Oltenita city (altitude 10 m).

Arge? River is the fifth longest river in Romania after Siret, Mure?, Olt and Some?, its length is 340 km and the river flows through four cities, Curtea de Arge?, Pite?ti, Gae?ti and Oltenita.

The results of the determinations of Cu, Cd, Zn and Pb, indicate that the Arge? River shows relatively low pollution.     

Will unit‐pricing enhance recycling?

Unit pricing is a program in solid waste management that integrates market instruments to encourage households to reduce waste generation and increase recycling. Many studies have shown that unit pricing is effective, especially when the evaluation is based on comparing outcomes before and after implementation. In this paper, we use the so-called difference-in-differences approach to evaluate unit pricing. This approach can provide a less-biased estimation, and can help to examine whether a unit pricing program generates less waste and higher recycling or results in illegal dumping in neighboring regions. Using the fee-per-bag program implemented in Taipei City, Taiwan, as a case study, we found that unit pricing does reduce the amount of garbage but its impact on recycling is not as significant as the current literature suggests. Moreover, the program causes a serious negative externality: more than 60%?of the garbage reduction in the city is due to increased dumping of waste in neighboring regions. As the impact of unit‐pricing on recycling is limited, policy-makers cannot rely solely on this program to enhance recycling in the management of municipal solid waste.     

Effects of climate and exurban development on nest predation and predator presence in the southern Appalachian Mountains (USA)

In the eastern United States, land-use and climate change have likely contributed to declines in the abundance of Neotropical migrant birds that occupy forest interiors, but the mechanisms are not well understood. We conducted a nest-predation experiment in southern Appalachian Mountain forests (North Carolina, U.S.A.) during the 2009 and 2010 breeding seasons to determine the effects of exurban development and temperature on predator presence and the average number of days until eggs in an artificial nest were disturbed by predators. We baited artificial nests with quail (Excalfactoria chinensi) eggs and monitored them for 18 days. We used clay eggs, track plates, and motion-triggered cameras to detect and identify nest predators. The average number of days a nest was undisturbed decreased as mean temperature increased and, to a lesser extent, as the density of buildings increased. Nests on the ground were more often depredated than those in trees, likely due to increased predation by opossum (Didelphis virginiana) and other carnivores. Raccoons (Procyon lotor), opossums, corvids (Corvus brachyrhynchos and Cyanocitta cristata), chipmunks (Tamias striatus), black bears (Ursus americanus), and domestic cats (Felis catus) were the most commonly detected predators. Presence of these predators did not vary as a function of mean temperature. Domestic cats and corvids were detected more frequently in plots with high rather than low densities of buildings. Forest-interior specialists and Neotropical migrants often nest in cool, high-elevation areas with low housing density. These bird species, especially those that nest on the ground, may be most vulnerable to increased nest predation if temperature and exurban development increase at higher elevations as anticipated.     

Occurrence of the non-native annual bluegrass on the Antarctic mainland and its negative effects on native plants

Few non-native species have colonized Antarctica, although increased human activity and accelerated climate change may increase their number, distributional range, and effects on native species on the continent. We searched 13 sites on the maritime Antarctic islands and 12 sites on the Antarctic Peninsula for annual bluegrass (Poa annua), a non-native flowering plant. We also evaluated the possible effects of competition between P. annua and 2 vascular plants native to Antarctica, Antarctic pearlwort (Colobanthus quitensis) and Antarctic hairgrass (Deschampsia antarctica). We grew the native species in experimental plots with and without annual bluegrass under conditions that mimicked the Antarctic environment. After 5 months, we measured photosynthetic performance on the basis of chlorophyll fluorescence and determined total biomass of both native species. We found individual specimens of annual bluegrass at 3 different sites on the Antarctic Peninsula during the 2007-2008 and 2009-2010 austral summers. The presence of bluegrass was associated with a statistically significant reduction in biomass of pearlwort and hairgrass, whereas the decrease in biomass of bluegrass was not statistically significant. Similarly, the presence of bluegrass significantly reduced the photosynthetic performance of the 2 native species. Sites where bluegrass occurred were close to major maritime routes of scientific expeditions and of tourist cruises to Antarctica. We believe that if current levels of human activity and regional warming persist, more non-native plant species are likely to colonize the Antarctic and may affect native species.     

Changes in Avian and Plant Communities of Aspen Woodlands over 12 Years after Livestock Removal in the Northwestern Great Basin

Abstract: Riparian and quaking aspen (Populus tremuloides) woodlands are centers of avian abundance and diversity in the western United States, but they have been affected adversely by land use practices, particularly livestock grazing. In 1990, cattle were removed from a 112,500‐ha national wildlife refuge in southeastern Oregon. Thereafter, we monitored changes in vegetation and bird abundance in years 1–3 (phase 1) and 10–12 (phase 2) in 17 riparian and 9 snow‐pocket aspen plots. On each 1.5‐ha plot, we sampled vegetation in 6 transects. Three times during each breeding season, observers recorded all birds 50 m to each side of the plot's 150‐m centerline for 25 minutes. We analyzed data with multivariate analysis of variance and paired t tests with p values adjusted for multiple comparisons. In both periods, riparian and snow‐pocket aspen produced extensive regeneration of new shoots ( stems/ha and 7079 stems/ha, respectively). By phase 2, a 64% increase in medium‐diameter trees in riparian stands indicated successful recruitment into the overstory, but this pattern was not seen in snow‐pocket stands, where the density of trees was over 2 times greater. By phase 2 in riparian and snow‐pocket stands, native forb cover had increased by 68% and 57%, respectively, mesic shrub cover had increased by 29% and 58%, and sagebrush cover had decreased by 24% and 31%. Total avian abundance increased by 33% and 39% in riparian and snow‐pocket aspen, respectively, ground or understory nesters increased by 133% and 67% and overstory nesters increased by 34% and 33%. Similarly, ground or understory foragers increased by 25% and 32%, aerial foragers by 55% and 57%, and overstory foragers by 66% and 43%. We interpreted the substantial regeneration of aspen shoots, increased densities of riparian forbs and shrubs, and increased avian abundances as a multitrophic‐level response to the total removal of livestock and as substantial movement toward recovery of biological integrity.