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101.
102.
Maie Bachmann Ruth Tomson Jaan Kalda Maksim Säkki Jaanus Lass Viiu Tuulik Hiie Hinrikus 《The Environmentalist》2007,27(4):511-517
This study was aimed to investigate the changes in the human electroencephalographic (EEG) signal caused by modulated low-level
microwaves. The 450 MHz microwave exposure modulated at 40 Hz and 70 Hz frequencies was applied to a group of 15 volunteers.
The field power density at the scalp was 0.16 mW/cm2. Ten cycles of the exposure (1 min on and 1 min off) at both modulation frequencies were applied. Analysis of the EEG signal
was performed using three different methods: nonlinear method of scaling analysis for length distribution of low variability
periods (LDLVP), relative changes in EEG energy (S-parameter) and beta ratio (H-parameter). The analysis revealed significant changes caused by microwave for the whole group (H-parameter method). The exposure caused increase of the EEG beta power (S-parameter method). Statistically significant changes in EEG were detected for four subjects (26.7%) at 40 Hz modulation frequency
(LDLVP method). 相似文献
103.
Derwent RG Stevenson DS Doherty RM Collins WJ Sanderson MG Johnson CE Cofala J Mechler R Amann M Dentener FJ 《Ambio》2005,34(1):54-59
A global three-dimensional Lagrangian chemistry-transport model STOCHEM is used to describe the European regional acid deposition and ozone air quality impacts along the Atlantic Ocean seaboard of Europe, from the SO2, NOx, VOCs and CO emissions from international shipping under conditions appropriate to the year 2000. Model-derived total sulfur deposition from international shipping reaches over 200 mg S m(-2) yr(-1) over the southwestern approaches to the British Isles and Brittany. The contribution from international shipping to surface ozone concentrations during the summertime, peaks at about 6 ppb over Ireland, Brittany and Portugal. Shipping emissions act as an external influence on acid deposition and ozone air quality within Europe and may require control actions in the future if strict deposition and air quality targets are to be met. 相似文献
104.
Monika Schaffner Hans-Peter Bader Ruth Scheidegger 《Environment, Development and Sustainability》2011,13(2):403-422
With the worldwide intensification of agriculture, non-point source pollution of surface waters has become a pressing issue. Conventional river water quality models consider non-point sources as accumulated entries into the rivers and do not investigate into the processes generating the pollution at its source, thus preventing the determination of effective mitigation measures. The models require extensive data inputs, which is a deficiency in many developing and emerging countries with limited data availability. The current study applies a Material Flow Model as a complementary approach to quantify non-point source pollution from agricultural areas. Rice farming in the Thachin River Basin is presented as a case study, with a focus on nutrients. The total nitrogen and phosphorus flows from rice farming to the river system are quantified, the key parameters influencing these flows are determined and potential mitigation measures are discussed. The results show that rice contributes considerable nutrient loads to the Thachin River Basin. Scenario simulations demonstrate that a significant nutrient load reduction could be achieved by following the official recommendations for fertilizer application, thus confirming the local efforts to introduce best management practice. Our results underline the importance of non-point source pollution control in intensive agricultural areas, particularly of tropical lowland delta areas such as the Central Plains of Thailand. The specific benefit of applying a Material Flow Model in this context is that with limited data availability, one can reach an understanding of the system and gain a first overview over its key pollution problems. This can serve as supportive basis for determining consecutive in-depth research requirements. 相似文献
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107.
Polyamines accumulate under various stress conditions in leaves of herbaceous plants. These stress responses, which are related to the physiological functions of polyamines, notably theirmembrane-stabilizing andradical-scavanging effect, are protective measures taken by the plant. Results from several natural spruce stands in Germany indicate that putrescine levels depend on the extent of damage. Needles with early signs of damage and needles with severe damage had significantly higher levels of putrescine than needles of healthy trees. Long-term fumigation of young beech and spruce trees with high concentrations of ozone, SO2, and NOx shows elevated levels of putrescine in leaves and needles. Thus, putrescine content can be used as a stress indicator in the assessment of novel forest damage even at early stages. 相似文献
108.
Breivik K Alcock R Li YF Bailey RE Fiedler H Pacyna JM 《Environmental pollution (Barking, Essex : 1987)》2004,128(1-2):3-16
During the last decade, a number of studies have been devoted to the sources and emissions of Persistent Organic Pollutants (POPs) at regional and global scales. While significant improvements in knowledge have been achieved for some pesticides, the quantitative understanding of the emission processes and emission patterns for "non-pesticide" POPs are still considered limited. The key issues remaining for the non-pesticide POPs are in part determined by their general source classification. For industrial chemicals, such as the polychlorinated biphenyls (PCBs), there is considerable uncertainty with respect to the relative importance of atmospheric emissions from various source categories. For PCBs, temperature is discussed as a potential key factor influencing atmospheric emission levels and patterns. When it comes to the unintentional by-products of combustion and industrial processes (PCDD/Fs), there is still a large uncertainty with respect to the relative contribution of emissions from unregulated sources such as backyard barrel burning that requires further consideration and characterisation. For hexachlorobenzene (HCB), the relative importance of primary and secondary atmospheric emissions in controlling current atmospheric concentrations remains one of the key uncertainties. While these and other issues may remain unresolved, knowledge concerning the emissions of POPs is a prerequisite for any attempt to understand and predict the distribution and fate of these chemicals on a regional and global scale as well as to efficiently minimise future environmental burdens. 相似文献
109.
We tested the rarely considered hypothesis that the ultraviolet portion (UVR, 280–400 nm) of the light spectrum affects patterns
of recruitment in reef-building corals. The premise for this hypothesis rests in the fact that biologically relevant intensities
of UVR penetrate to considerable depths (>24 m) in the clear waters surrounding many coral reefs, and that reef organisms
allocate substantial resources to prevent and repair UVR damage. The ability of larvae spawned by the brown morph of the Caribbean
coral, Porites astreoides, to detect and avoid UVR was assessed in petri dishes where one-half of the dish was shielded from UVR and the other exposed.
Observations made every 30 min between 10:30 and 13:30 h showed significantly higher densities of larvae swimming in regions
shielded from UVR. To determine how this behavior affects settlement patterns, larvae collected from P. astreoides adults at 18 m depth were released into chambers deployed at 17 m depth where they were given a choice of three different
light regions in which to settle: PAR (PAR=400–700 nm), PAR+UVAR (UVAR=320–400 nm), and PAR+UVAR+UVBR (UVBR=280–320 nm). At
the end of the experiment, greater numbers of P. astreoides larvae had settled in the region of the tube where UVR was reduced than would be expected if dispersion were random. To our
knowledge, this is the first demonstration in any reef-building coral species that planula larvae can detect UVR and that
it affects their choice of a settlement site. These results indicate that the capacity to detect and avoid habitats with biologically
damaging levels of UVR may be one factor contributing to the successful recruitment of coral larvae. 相似文献
110.