Exposure to polybrominated diphenyl ethers and tetrabromobisphenol A among computer technicians

This study investigates exposure to polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA), which are used as flame retardants in electronic equipment, in a group of technicians with intense computer work. Thirteen PBDE congeners and TBBPA were quantified in serum from 19 computer technicians. Previously investigated groups of hospital cleaners with no computer experience, and clerks working full-time at computer screens were used for comparison. The computer technicians had serum concentrations of BDE-153, BDE-183 and BDE-209 that were five times higher than those reported among hospital cleaners and computer clerks. The median levels observed among the computer technicians were 4.1, 1.3, and 1.6 pmol/g lipid weight, respectively. In contrast, for BDE-47 there was no difference between the computer technicians and the others. BDE-100, BDE-203, and three structurally unidentified octa-BDEs and three nona-BDEs, were present in almost all samples from the computer technicians. Further, TBBPA was detected in 8 out of 10 samples. The levels of BDE-153, BDE-183, and one of the octa-BDEs were positively correlated with duration of computer work among technicians. On a group level an exposure gradient was observed, from the least exposed cleaners to the clerks, and to the highest exposed group of computer technicians. A dose (duration of computer work)-response relationship among computer technicians was demonstrated for some higher brominated PBDE congeners. Thus, it is evident that PBDEs used in computers and electronics, including the fully brominated BDE-209, contaminate the work environment and accumulate in the workers tissues.     

Synthesis of [13C]- and [14C]-labeled phenolic humus and lignin monomers

Natural phenolic monomers are ubiquitous in the environment and are involved in the stabilization of atmospheric carbon and the transformation of xenobiotics. Investigations on the stabilization of phenolic carbons and their environmental fate are hampered by the unavailability of commercial [13C]- and [14C]-labeled phenols. Here we report the complete chemical synthesis of the lignin and humus structural monomers p-coumaric, ferulic, and caffeic acids, p-hydroxybenzaldehyde, protocatechualdehyde, vanillin, catechol, and guaiacol, uniformly [13C]- or [14C]-labeled in the aromatic ring, starting from commercially available [U-ring-13C]- or [U-ring-14C]-labeled phenol. The synthesis of these compounds involved selective ortho-hydroxylation of the aromatic ring, Friedel-Crafts alkylation, and Knoevenagel condensation. [U-ring-13C]- or [U-ring-14C]-p-coumaric acid was synthesized via p-hydroxybenzaldehyde with a 75% yield with respect to phenol. Synthesis of [U-ring-13C]- or [U-ring-14C]-ferulic acid, consisting of six single steps via guaiacol and vanillin, had an overall yield of up to 45%. Uniformly ring-labeled caffeic acid was synthesized either via catechol and protocatechualdehyde in five single steps, yielding [U-ring-14C]-caffeic acid with a 37% yield, or via guaiacol, vanillin, and ferulic acid in seven steps, yielding [U-ring-13C]-caffeic acid with an 18% yield. Ferulic acid, [14C]-labeled at beta-C of the propenoic side chain, was synthesized from [2-14C]-malonic acid under Knoevenagel conditions with a 67% yield with respect to malonic acid. Demethylation of the [beta-14C]-ferulic acid with BBr3 in CH3CN resulted in [beta-14C]-caffeic acid with a 62% yield. All [U-ring-13C]-labeled phenolic products were analyzed by 13C nuclear magnetic resonance (13C-NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS).     

Priming effects on PAH degradation and ecotoxicity during a phytoremediation experiment

An experiment was conducted to distinguish priming effects from the effects of phytoremediation of a creosote-polluted soil. The concentration of 13 polycyclic aromatic hydrocarbons (PAHs), and their combined soil toxicity (using four bioassays), was determined on recently excavated, homogenized soil and on such soil subjected to a time-course phytoremediation experiment with lucerne. The results showed a high priming effect, with minor positive and synergistic effects of planting and fertilization on PAH degradation rates. At the end of the experiment, PAH degradation reached 86% of the initial 519 mg PAHs kg(-1). Two of the four toxicity tests (bioluminescence inhibition and ostracod growth inhibition) corroborated the chemical data for residual PAHs, and indicated a significant reduction in soil toxicity. We conclude that priming effects can easily surpass treatment effects, and that an unintentional pre-incubation that ignores these effects can jeopardize the full quantitative assessment of in situ bioremediation of contaminated soil.     

Nitrate dynamics in an alpine forest site (Mühleggerköpfl) O and N stable isotope analysis in natural water samples

Stable isotope analysis of¹⁵N/¹⁴N and¹⁸O/¹⁶O - nitrate was used to investigate the nitrate dynamics and potential groundwater pollution in an Alpine forest stand in Tyrol/Austria. The dynamics of δ¹⁵−N_nitrate values were followed in a forest ecosystem. The stable isotopic values of the throughfall are comparable with other studies. The completely decoupled dynamics of the δ¹⁵−N_nitrate of the precipitation and the surface water was observed. High variations in δ¹⁵-N - nitrate values in rainfall indicate that nitrate of different sources is deposited at that site. A significant correlation between the δ¹⁵N_nitrate values of the surface water and soil water was obtained, while no significant correlation between the δ¹⁵N_nitrate values of any precipitation sample with the surface water could be found. This suggests that the main source of nitrate in soil water originates from microbiological activity such as nitrification reactions and less from nitrate input by deposition. The results of δ¹⁸O_nitrate measurements strongly supported the microbiological origin of nitrate in the surface and soil water. In an additional lysimeter experiment,¹⁵N - labelled nitrate was applied to study nitrate transport in soil. After 130 days and the collection of 300 L leachate, a total of 52% of the applied nitrate was detected in seepage water.

     

Ansatz zur Optimierung biologischer Reinigungsstufen durch das Ph?nomen der ‘biologischen Resonanz’

Ohne Zusammenfassung Siehe UWSF12 (6) 350 (2000)     

Modelling dynamics of managed tropical rainforests—An aggregated approach

The overuse of rainforests in the last century and its consequences necessitate a rethinking of logging policies. To this end models have been developed to simulate rainforest dynamics and to allow optional management strategies to be evaluated. Parameterisation of presently existing models for a certain site needs a lot of work, thus the parameterisation effort is too high to apply the models to a wide range of rainforests. Hence, in this paper we introduce the simplified model FORREG using the knowledge we have gained from a more complex model, FORMIX3-Q.     

Nebenprodukte der Lebensmittelverarbeitung als Futtermittel

The use of byproducts of the food industry as feedstuffs for animals has become a significant conflict for agriculture. Public regulations concerning the improvement of nutrient recycling and economic production with less financial support, on one hand, and the avoidance of all risks for human and animal health, on the other hand, are seen to affect agriculture practice. In this paper, information is presented about the quantities and quality of byproducts of the food industry used as feedstuffs. Also the nutritional and economical value of meat meal is discussed including ecological aspects. Other use or the disposal of products high in their nutritional value should, in the future, be no alternatives to the use as feed for animals, when risks are carefully controlled, because of the necessity for a sustainable agriculture and economy.