Drowsy drivers: The effect of light and circadian rhythm on crash occurrence

Drowsiness has been recognized as a pervasive problem for drivers, with effects comparable to alcohol. Alcohol, however, has a clear legal limit for impairment; there are no comparable criteria to suggest sleepiness. Drowsiness has been associated with light and circadian rhythm. To investigate the joint effects of these factors on crash occurrence, along with other factors, single vehicle crashes reported in Ontario (1999–2004) were analyzed. Crashes occurring at four times of day, when light varies and circadian rhythm is low (2–5 a.m. and 2–4 p.m.) and with similar light conditions and higher circadian rhythm (9–11 p.m. and 10 a.m.–12 noon). Logistic regression was used to see how light and other factors are associated with single vehicle crashes occurring at times of low circadian rhythm, when drowsiness is more likely.Initial results indicated many circumstances associated with occurrence at these times: the age and sex of the driver and reported driver condition as well as weather. There is, however, an interaction between light and presumed alertness. In separate analyses for daytime and night time crashes most variables were significant for nighttime crashes but not for daytime events. The effects of alcohol and youth remained. A lack of light may exacerbate the effects of other factors at times of low alertness; this should be further investigated in controlled environments such as sleep laboratories and/or driving simulators.     

Effects of arsenic on nitrate metabolism in arsenic hyperaccumulating and non-hyperaccumulating ferns

This study investigated the effects of arsenic on the in vitro activities of the enzymes (nitrate reductase and nitrite reductase) involved in nitrate metabolism in the roots, rhizomes, and fronds of four-month old Pteris vittata (arsenic – hyperaccumulator) and Pteris ensiformis (non-arsenic--hyperaccumulator) plants. The arsenic treatments (0, 150, and 300 μM as sodium arsenate) in hydroponics had adverse effects on the root and frond dry weights, and this effect was more evident in P. ensiformis than in P. vittata. Nitrate reductase and nitrite reductase activities of arsenate-treated plants were reduced more in P. ensiformis than in P. vittata. This effect was accompanied by similar decreases in tissue NO₃^? concentrations. Therefore, this decrease is interpreted as being indirect, i.e., the consequence of the reduced NO₃^? uptake and translocation in the plants. The study shows the difference in the tolerance level of the two Pteris species with varying sensitivity to arsenic.     

Performance of an in situ passive sampling system for metals in stormwater

A passive sampler has been developed and is demonstrated in situ for urban runoff. The passive sampler is compared to conventional composite (time-dependent and flow-weighted) bottle sampling during and between storm events. The sampling was carried out at established stormwater stations; before and after a stormwater detention pond. In situ deployment of the passive sampler provides the metal concentrations, corresponding to the electrochemically available fraction of total metal, for time-dependent samples collected in parallel. The sampler provides improved accuracy compared to bottle sampling because contamination during sample transport and handling is minimised. Laboratory handling is reduced by direct analysis of the accumulated metals on the receiving membrane by laser ablation inductively coupled plasma mass spectrometry. Passive sampling also solves the problem of metal speciation change during transport to the laboratory, which is a potential problem for bottle samples. The low cost and convenience of the passive sampler and subsequent analysis should allow significantly more extensive spatial and temporal monitoring of metals in the aquatic environment than has previously been possible.     

Keeping pace with forestry: Multi-scale conservation in a changing production forest matrix

The multi-scale approach to conserving forest biodiversity has been used in Sweden since the 1980s, a period defined by increased reserve area and conservation actions within production forests. However, two thousand forest-associated species remain on Sweden’s red-list, and Sweden’s 2020 goals for sustainable forests are not being met. We argue that ongoing changes in the production forest matrix require more consideration, and that multi-scale conservation must be adapted to, and integrated with, production forest development. To make this case, we summarize trends in habitat provision by Sweden’s protected and production forests, and the variety of ways silviculture can affect biodiversity. We discuss how different forestry trajectories affect the type and extent of conservation approaches needed to secure biodiversity, and suggest leverage points for aiding the adoption of diversified silviculture. Sweden’s long-term experience with multi-scale conservation and intensive forestry provides insights for other countries trying to conserve species within production landscapes.

     

Scheelite weathering and tungsten (W) mobility in historical oxidic-sulfidic skarn tailings at Yxsjöberg,Sweden

Environmental Science and Pollution Research - More knowledge of the geochemical behavior of tungsten (W) and associated contamination risks is needed. Therefore, weathering of scheelite (CaWO4)...     

A New Phosphorus Paradigm for the Baltic Proper

The external phosphorus (P) loading has been halved, but the P content in the water column and the area of anoxic bottoms in Baltic proper has increased during the last 30 years. This can be explained by a temporary internal source of dissolved inorganic phosphorus (DIP) that is turned on when the water above the bottom sediment becomes anoxic. A load-response model, explaining the evolution from 1980 to 2005, suggests that the average specific DIP flux from anoxic bottoms in the Baltic proper is about 2.3 g P m⁻² year⁻¹. This is commensurable with fluxes estimated in situ from anoxic bottoms in the open Baltic proper and from hydrographic data in the deep part of Bornholm Basin. Oxygenation of anoxic bottoms, natural or manmade, may quickly turn off the internal P source from anoxic bottoms. This new P-paradigm should have far-reaching implications for abatement of eutrophication in the Baltic proper.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-013-0441-3) contains supplementary material, which is available to authorized users.     

Impacts of two best management practices on Pb weathering and leachability in shooting range soils

This study investigated the impacts of two best management practices (BMPs) recommended by US Environmental Protection Agency on Pb weathering and leachability in shooting range soils. The two BMPs included replacing soil berm with sand berm and periodically removing bullets or shot from a berm. A column experiment corresponding to the first BMP was conducted by mixing the bullets with sand/soil, or placing bullets on the surface of sand/soil. After a 16–18-week incubation under high or low rainfall simulations, total Pb concentrations in sand were lower than that in soil. Total leachable Pb in sand (8.48 and 5.52 μg?kg^?1) was also lower than that in soil (60.0 and 30.4 μg?kg^?1) when bullets were mixed with sand/soil; however, they were comparable when bullets were placed on the sand/soil surface. These results indicate that lower Pb concentration in the sand than in soil may be attributed to reduced weathering of bullets. Mechanical removal of Pb bullets in the field transferred Pb from large to finer particles, increasing total Pb in the soil (<2 mm) from 2,170 to 5,000 mg?kg^?1. In contrast, mechanical removal of Pb shot effectively reduced the shot in the soil by 86–92 %. Thus, we concluded that, while replacing soil berm with sand berm can slow down Pb weathering, it may increase Pb leachability in the long term. Removal of Pb bullets and Pb shot can be effective, but caution needs to be exercised to minimize the adverse impacts, especially in pistol/rifle ranges because of increased total Pb content in the soil.     

Neutralization/prevention of acid rock drainage using mixtures of alkaline by-products and sulfidic mine wastes

Backfilling of open pit with sulfidic waste rock followed by inundation is a common method for reducing sulfide oxidation after mine closure. This approach can be complemented by mixing the waste rock with alkaline materials from pulp and steel mills to increase the system’s neutralization potential. Leachates from 1 m³ tanks containing sulfide-rich (ca.30 wt %) waste rock formed under dry and water saturated conditions under laboratory conditions were characterized and compared to those formed from mixtures. The waste rock leachate produced an acidic leachate (pH?<?2) with high concentrations of As (65 mg/L), Cu (6 mg/L), and Zn (150 mg/L) after 258 days. The leachate from water-saturated waste rock had lower concentrations of As and Cu (<2 μg/L), Pb and Zn (20 μg/L and 5 mg/L), respectively, and its pH was around 6. Crushed (<6 mm) waste rock mixed with different fractions (1–5 wt %) of green liquid dregs, fly ash, mesa lime, and argon oxygen decarburization (AOD) slag was leached on a small scale for 65 day, and showed near-neutral pH values, except for mixtures of waste rock with AOD slag and fly ash (5 % w/w) which were more basic (pH?>?9). The decrease of elemental concentration in the leachate was most pronounced for Pb and Zn, while Al and S were relatively high. Overall, the results obtained were promising and suggest that alkaline by-products could be useful additives for minimizing ARD formation.     

Source,distribution, and health risk assessment of polycyclic aromatic hydrocarbons in urban street dust from Tianjin,China

To better assess and understand potential health risk of urban residents exposed to urban street dust, the total concentration, sources, and distribution of 16 polycyclic aromatic hydrocarbons (PAHs) in 87 urban street dust samples from Tianjin as a Chinese megacity that has undergone rapid urbanization were investigated. In the meantime, potential sources of PAHs were identified using the principal component analysis (PCA), and the risk of residents’ exposure to PAHs via urban street dust was calculated using the Incremental Lifetime Cancer Risk (ILCR) model. The results showed that the total PAHs (∑PAHs) in urban street dust from Tianjin ranged from 538 μg kg^?1 to 34.3 mg kg^?1, averaging 7.99 mg kg^?1. According to PCA, the two to three- and four to six-ring PAHs contributed 10.3 and 89.7 % of ∑PAHs, respectively. The ratio of the sum of major combustion specific compounds (ΣCOMB)?/?∑PAHs varied from 0.57 to 0.79, averaging 0.64. The ratio of Ant/(Ant?+?Phe) varied from 0.05 to 0.41, averaging 0.10; Fla/(Fla?+?Pyr) from 0.40 to 0.68, averaging 0.60; BaA/(BaA?+?Chry) from 0.29 to 0.51, averaging 0.38; and IcdP/(IcdP?+?BghiP) from 0.07 to 0.37, averaging 0.22. The biomass combustion, coal combustion, and traffic emission were the main sources of PAHs in urban street dust with the similar proportion. According to the ILCR model, the total cancer risk for children and adults was up to 2.55?×?10^?5 and 9.33?×?10^?5, respectively.