Exhaust fumes of paraffin, beeswax and stearin candles without any further paint or decorative element were analysed for the toxicological important substance classes of PCDD/PCDF, PAH and short chain aldehydes. The candle waxes and wicks were investigated for chlorinated dioxins, furans and some known precursors. Toxicological risk assessment shows that emissions of the investigated candles are much lower than all administrative limitation values — even under “worst case conditions”. Thus, they do not produce a toxicological risk for human health. 相似文献
A simple, rapid, and efficient dispersive liquid–liquid microextraction method, followed by UV–Vis spectrophotometry was developed for the preconcentration and determination of Pd ions in water samples. Pd ions react with α-furildioxime (chelating agent) to form a hydrophobic complex. Various parameters were altered to study and optimize their effects on the extraction efficiency, such as pH, ligand concentration, the type and volume of extraction and dispersive solvents, extraction time, and salt concentration. Under optimized conditions, the method exhibited an enrichment factor (Corg/Caq) of 25 and recovery more than 98 % within a very short extraction time. The linearity of the method ranged from 10 to 200 μg?L?1. The limit of detection was 1.1 μg?L?1. The relative standard deviation for the concentration of 100 μg?L?1 of Pd was 2.3 % (n?=?10). Finally, the developed method was successfully applied to the extraction and determination of Pd in tap, river, mineral, and sea water samples. 相似文献
The presence of Persistent Organic Pollutants (POPs) is identified as a global problem for humans and the environment. POPs, in fact, are released by numerous static, mobile and diffuse sources, and are frequently seen to be widespread. Due to the global dimension of the potential environmental impacts, POP related problems can only be handled on the basis of international agreements. Concerning this aspect, some international activities are presented and general requirements are discussed in view of the international POPs management, both for static and diffuse releases 相似文献
Im Rahmen eines Untersuchungsprogrammes zur Schadstoffemission von Paraffin-, Stearin- und Bienenwachskerzen ohne Farb- und
Lackbeimischungen wurden sowohl die Wachse und Dochte als auch die Brandgase dieser Kerzen auf die toxikologisch besonders
relevanten Schadstoffklassen der PCDD/PCDF, PAK und kurzkettigen Aldehyde untersucht. Die toxikologische Bewertung kommt selbst
bei einem angenommenen „worst case“-Szenario und unter Berücksichtigung von geltenden Grenz- und Richtwerten zu dem Ergebnis,
da? von den untersuchten Kerzen kein zus?tzliches Gesundheitsrisiko ausgeht.
Exhaust fumes of paraffin, beeswax and stearin candles without any further paint or decorative element were analysed for the
toxicological important substance classes of PCDD/PCDF, PAH and short chain aldehydes. The candle waxes and wicks were investigated
for chlorinated dioxins, furans and some known precursors. Toxicological risk assessment shows that emissions of the investigated
candles are much lower than all administrative limitation values — even under “worst case conditions”. Thus, they do not produce
a toxicological risk for human health. 相似文献
Pollution and destruction of the environment due to the accumulation of non-degradable plastics are some of the most important concerns in the world. A significant amount of this waste is related to the polymers used in food packaging. Therefore, experts in the food industry have been looking for suitable biodegradable alternatives to synthetic polymers. Preparing biocompatible and biodegradable films based on starch is a good choice. In this study, various factors affecting films of starch/polyvinyl alcohol (PVA)/containing ZnO nanoparticles such as the amount of starch, PVA, glycerol, and ZnO were evaluated by response surface methodology (RSM). Film formation by solvent casting method, mechanical properties, swelling, solubility, and water vapor permeability (WVP) were selected as responses of RSM. The results showed that hydrogen bonding interactions between polyvinyl alcohol and starch improved the film formation. The effect of glycerol and PVA content on the mechanical strength was contrary to each other. As the amount of PVA increased, the tensile strength first decreased and then increased. The value of WVP was for all Runs from 0 to 6.77?×?10??8 g m??1 s??1 Pa??1. Finally, films with high film formation, maximum tensile strength, and high elongation at break, minimum solubility, permeability, and swelling were optimized.
This paper is concerned with regional frequency analysis of hydrologic multiyear droughts. A drought event is defined by three parameters: severity, duration, and magnitude. A method is proposed here to standardize drought severities with a duration adjustment to enable comparison among drought events. For purposes of a regional study, the index drought method is selected and applied to standardized droughts to give a regional frequency curve. However, the recurrence intervals of the drought events obtained from index drought method are limited to the historic period of record. Therefore, by taking advantage of random variations of droughts in both time and space, a multivariate simulation model is used to estimate exceedence probabilities associated with regional drought maxima. This method, named the regional extreme drought method, is capable of generating a series of drought events which, although they have not occurred historically, are more severe than historic events. By combining the results of the index drought method and regional extreme drought analysis, a regional drought probability graph is constructed which ranges from severe droughts to more frequent droughts. This procedure is applied to the mean annual flow records of streams located in the San Joaquin Valley of California, and drought-severity-frequency plots are prepared for 1-year, 2-year, and 3-year durations. 相似文献