Although arsenic (As) contamination of groundwater in the Bengal Basin has received wide attention over the past decade, comparative studies of hydrogeochemistry in geologically different sub-basins within the basin have been lacking. Groundwater samples were collected from sub-basins in the western margin (River Bhagirathi sub-basin, Nadia, India; 90 samples) and eastern margin (River Meghna sub-basin; Brahmanbaria, Bangladesh; 35 samples) of the Bengal Basin. Groundwater in the western site (Nadia) has mostly Ca-HCO(3) water while that in the eastern site (Brahmanbaria) is much more variable consisting of at least six different facies. The two sites show differences in major and minor solute trends indicating varying pathways of hydrogeochemical evolution However, both sites have similar reducing, postoxic environments (p(e): +5 to -2) with high concentrations of dissolved organic carbon, indicating dominantly metal-reducing processes and similarity in As mobilization mechanism. The trends of various redox-sensitive solutes (e.g. As, CH(4), Fe, Mn, NO(3)(-), NH(4)(+), SO(4)(2-)) indicate overlapping redox zones, leading to partial redox equilibrium conditions where As, once liberated from source minerals, would tend to remain in solution because of the complex interplay among the electron acceptors. 相似文献
As part of an assessment of land-based sources of pollution in Jobos Bay, Puerto Rico, sediment samples were collected at
43 sites to characterize concentrations of a suite of pollutants, including metals. Fifteen major and trace metals (Ag, Al,
As, Cd, Cr, Cu, Fe, Hg, Mn Ni, Pb, Sb, Se, Sn, and Zn) were measured along with total organic carbon and grain size in surficial
sediments. For most metals, maximum concentrations were seen in the eastern bay; however, values were still within concentration
ranges found in other estuarine systems. In contrast, silver was higher in the western region. In general, metal distribution
in the bay was positively correlated with grain size. Additionally, correlations between Al and other metals suggest natural
sources for metals. The data presented here suggest that, although the Jobos Bay watershed contains both urban centers along
with industrial and agricultural developments, anthropogenic inputs of metals may be negligible. 相似文献
Based on a recent survey of German composting plants an evaluation of costs and benefits of composting was attempted. In this regard, several economical, ecological and legal aspects and some interrelations are discussed in this paper. A special emphasis is placed on the fees and compost prices of composting plants. It is also shown how the legal framework provides the economic basis for composting in Germany, how economical and ecological costs and benefits could be assessed, and why it is so difficult to determine the value of composting. 相似文献
Our interest is in electricity demand and the temperature aspects of climate change. Electricity consumption is of interest
both from the perspectives of adaptation to climate change and emission reductions. We study the relationship between European
electricity consumption and outdoor temperature and other variables, using a panel data set of 31 countries. Apart from providing
a rare quantitative window into adaptation, the study contributes demand system parameters with respect to price and income.
The results suggest that weather has a statistically significant effect on electricity demand, with effects that are of plausible
magnitude. In a simulation of climate change for the next 100 years—other factors held constant—we find that the demand for
heating will decrease in Northern Europe while the demand for cooling will increase in Southern Europe. In countries like
Cyprus, Greece, Italy, Malta, Spain, and Turkey the net effect of increased cooling outweighs decreased heating consumption
whereas in most of Europe the opposite holds. The largest estimated partial impact is 20%, which predicted increase in adaptive
consumption for Turkey and decrease in adaptive consumption for Latvia. Estimated elasticities with respect to income and
price are 0.8 and minus 0.2 respectively: plausible in the light of the literature. As a discussion item, we add that electricity
consumption changes due to temperature change likely will be small compared to those due to other factors, such as changes
in income, demography and technology. The study does not include effects of climate change other than through electricity
consumption. 相似文献
Objective: Standard deviation of lateral position (SDLP) is often the primary outcome in experimental studies on impaired driving. However, other measures may be easier and more practical to obtain and reflect a broader range of driving-related behaviors. We wanted to assess the validity and sensitivity of a range of measures in a driving simulator as well as during real driving and compare these to SDLP.
Methods: Twenty healthy male volunteers undertook 6 driving trials each, 3 in a regular car on a closed track resembling rural road conditions and 3 in a simulator with an identical driving scenario. Ethanol was used as impairing substance due to its well-characterized effects on driving. The subjects were tested sober and at blood alcohol concentrations (BAC) of approximately 0.5 and 0.9 g/L. We explored dose–response relationships between BAC and a range of driving-related measures, as well as their BAC-dependent effect sizes.
Results: In simulator driving, ethanol intake increased steering wheel reversal frequency, steering wheel movement measures, average speed, standard deviation of speed, and pedal use frequency. At the test track, only steering wheel movement and standard deviation of speed were significantly correlated to BAC. Likewise, reaction to unexpected incidents and observance of red traffic lights were adversely affected by ethanol in the simulator but not at the test track. Whereas SDLP showed a relatively large effect size that was similar in simulated and real driving, all other measures demonstrated smaller effect sizes, with less pronounced BAC effects on the test track than in the simulator.
Conclusions: The results suggest that the driving-related measures explored in this study are less sensitive to alcohol-mediated driving impairment than SDLP, especially during real (test track) driving. The discrepancy in effect sizes between simulated and real driving may imply low external validity of these measures in simulator studies. 相似文献
Workers' motivation to actively take part in improvements to the work environment is assumed to be important for the efficiency of investments for that purpose. That gives rise to the need for a tool to measure this motivation.
Method
A questionnaire to measure motivation for improvements to the work environment has been designed. Internal consistency and test-retest reliability of the domains of the questionnaire have been measured, and the factorial structure has been explored, from the answers of 113 employees.
Results
The internal consistency is high (0.94), as well as the correlation for the total score (0.84). Three factors are identified accounting for 61.6% of the total variance.
Discussion
The questionnaire can be a useful tool in improving intervention methods.
Impact on Industry
The expectation is that the tool can be useful, particularly with the aim of improving efficiency of companies' investments for work environment improvements. 相似文献
Methods for measurements and the potential for occupational exposure to organophosphates (OPs) originating from turbine and hydraulic oils among flying personnel in the aviation industry are described. Different sampling methods were applied, including active within-day methods for OPs and VOCs, newly developed passive long-term sample methods (deposition of OPs to wipe surface areas and to activated charcoal cloths), and measurements of OPs in high-efficiency particulate air (HEPA) recirculation filters (n = 6). In total, 95 and 72 within-day OP and VOC samples, respectively, have been collected during 47 flights in six different models of turbine jet engine, propeller and helicopter aircrafts (n = 40). In general, the OP air levels from the within-day samples were low. The most relevant OP in this regard originating from turbine and engine oils, tricresyl phosphate (TCP), was detected in only 4% of the samples (min-max 相似文献