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51.
Sari Vilhunen Heikki Särkkä Mika Sillanpää 《Environmental science and pollution research international》2009,16(4):439-442
Background, aim, and scope The novel system of ultraviolet light-emitting diodes (UV LEDs) was studied in water disinfection. Conventional UV lamps,
like mercury vapor lamp, consume much energy and are considered to be problem waste after use. UV LEDs are energy efficient
and free of toxicants. This study showed the suitability of LEDs in disinfection and provided information of the effect of
two emitted wavelengths and different test mediums to Escherichia coli destruction.
Materials and methods Common laboratory strain of E. coli (K12) was used and the effects of two emitted wavelengths (269 and 276 nm) were investigated with two photolytic batch reactors
both including ten LEDs. The effects of test medium were examined with ultrapure water, nutrient and water, and nutrient and
water with humic acids.
Results Efficiency of reactors was almost the same even though the one emitting higher wavelength had doubled optical power compared
to the other. Therefore, the effect of wavelength was evident and the radiation emitted at 269 nm was more powerful. Also,
the impact of background was studied and noticed to have only slight deteriorating effect. In the 5-min experiment, the bacterial
reduction of three to four log colony-forming units (CFU) per cubic centimeter was achieved, in all cases.
Discussion When turbidity of the test medium was greater, part of the UV radiation was spent on the absorption and reactions with extra
substances on liquid. Humic acids can also coat the bacteria reducing the sensitivity of the cells to UV light. The lower
wavelength was distinctly more efficient when the optical power is considered, even though the difference of wavelengths was
small. The reason presumably is the greater absorption of DNA causing more efficient bacterial breakage.
Conclusions UV LEDs were efficient in E. coli destruction, even if LEDs were considered to have rather low optical power. The effect of wavelengths was noticeable but
the test medium did not have much impact.
Recommendations and perspectives This study found UV LEDs to be an optimal method for bacterial disinfection. The emitted wavelength was found to be an essential
factor when using LEDs; thus, care should be taken in selecting the proper LED for maximum disinfection. 相似文献
52.
Kiljunen M Vanhatalo M Mäntyniemi S Peltonen H Kuikka S Kiviranta H Parmanne R Tuomisto JT Vuorinen PJ Hallikainen A Verta M Pönni J Jones RI Karjalainen J 《Ambio》2007,36(2-3):257-264
This study examines the extent to which Finnish human dietary intake of organochlorines (PCDD/Fs and PCBs) originating from Northern Baltic herring can be influenced by fisheries management. This was investigated by estimation of human intake using versatile modeling tools (e.g., a herring population model and a bioenergetics model). We used a probabilistic approach to account for the variation in human intake of organochlorines originating from the variation among herring individuals. Our estimates were compared with present precautionary limits and recommendation for use. The results show that present consumption levels and frequencies of herring give a high probability of exceeding recommended intake limits of PCDD/Fs and PCBs. Furthermore, our results clearly demonstrate that in the risk management of dioxinlike organochlorines, regulating fishing (in this case increasing fishing pressure) is a far less effective way to decrease the risk than regulating the consumption of herring. Increased fishing would only slightly decrease organochlorine concentrations of herring in the Finnish fish market. 相似文献
53.
Heikki Haapala Ryunosuke Kikuchi 《Environmental science and pollution research international》2000,7(4):189-190
A new application of the Scanning Electron Microscope (SEM) equipped with an Energy Dispersive X-ray Microanalyzer (EDX) has
been developed to study the distribution of airborne dust emissions. This technique makes it possible to identify the particles
and measure the amount of dust deposition on the surface of the biomonitoring material. Pine bark or needles and moss can
easily be used as the study material. A map indicating pollution levels and distribution can be drawn on the basis of the
measured data. 相似文献
54.
Kallio ER Voutilainen L Vapalahti O Vaheri A Henttonen H Koskela E Mappes T 《Ecology》2007,88(8):1911-1916
The influence of pathogens on host fitness is one of the key questions in infection ecology. Hantaviruses have coevolved with their hosts and are generally thought to have little or no effect on host survival or reproduction. We examined the effect of Puumala virus (PUUV) infection on the winter survival of bank voles (Myodes glareolus), the host of this virus. The data were collected by monitoring 22 islands over three consecutive winters (a total of 55 island populations) in an endemic area of central Finland. We show that PUUV infected bank voles had a significantly lower overwinter survival probability than antibody negative bank voles. Antibody negative female bank voles from low-density populations living on large islands had the highest survival. The results were similar at the population level as the spring population size and density were negatively correlated with PUUV prevalence in the autumn. Our results provide the first evidence for a significant effect of PUUV on host survival suggesting that hantaviruses, and endemic pathogens in general, deserve even more attention in studies of host population dynamics. 相似文献
55.
Mämmelä P Tuomainen A Vartiainen T Lindroos L Kangas J Savolainen H 《Journal of environmental monitoring : JEM》2002,4(2):187-189
A high-performance liquid chromatography (HPLC) method for biomonitoring of occupational wood dust exposure based on nasal lavage as a biomonitoring matrix was developed. Gallic acid (GA) was chosen as the indicator compound for oak dust exposure. From the chromatographic profile of ash dust, four peaks were chosen as indicator compounds. Phenolic indicator compounds were analysed by HPLC. Personal dust samples and corresponding nasal lavage samples were collected from 16 workers exposed to oak dust and six to ash dust. The dust concentrations in the workers' breathing zone varied between 0.7 and 13.8 mg m(-3). The indicators revealed the nature of the wood dust inhaled. For the workers who did not use respirators, the correlation between the dust and corresponding indicator compound in their nasal lavage was significant; r2 = 0.59 (n = 12) for oak dust and r2 = 0.58 (n = 6) for ash dust, respectively. Further, the correlation for oak dust workers who used respirators was r = 0.67 (n = 4). Nasal lavage sampling and HPLC analysis of polyphenol indicator compounds are promising tools for measuring wood dust exposure. Although further validation is necessary, determination of the individual dose may prove invaluable in prospective epidemiological studies. 相似文献
56.
Callaghan TV Björn LO Chernov Y Chapin T Christensen TR Huntley B Ims RA Johansson M Jolly D Jonasson S Matveyeva N Panikov N Oechel W Shaver G Henttonen H 《Ambio》2004,33(7):436-447
Species individualistic responses to warming and increased UV-B radiation are moderated by the responses of neighbors within communities, and trophic interactions within ecosystems. All of these responses lead to changes in ecosystem structure. Experimental manipulation of environmental factors expected to change at high latitudes showed that summer warming of tundra vegetation has generally led to smaller changes than fertilizer addition. Some of the factors manipulated have strong effects on the structure of Arctic ecosystems but the effects vary regionally, with the greatest response of plant and invertebrate communities being observed at the coldest locations. Arctic invertebrate communities are very likely to respond rapidly to warming whereas microbial biomass and nutrient stocks are more stable. Experimentally enhanced UV-B radiation altered the community composition of gram-negative bacteria and fungi, but not that of plants. Increased plant productivity due to warmer summers may dominate food-web dynamics. Trophic interactions of tundra and sub-Arctic forest plant-based food webs are centered on a few dominant animal species which often have cyclic population fluctuations that lead to extremely high peak abundances in some years. Population cycles of small rodents and insect defoliators such as the autumn moth affect the structure and diversity of tundra and forest-tundra vegetation and the viability of a number of specialist predators and parasites. Ice crusting in warmer winters is likely to reduce the accessibility of plant food to lemmings, while deep snow may protect them from snow-surface predators. In Fennoscandia, there is evidence already for a pronounced shift in small rodent community structure and dynamics that have resulted in a decline of predators that specialize in feeding on small rodents. Climate is also likely to alter the role of insect pests in the birch forest system: warmer winters may increase survival of eggs and expand the range of the insects. Insects that harass reindeer in the summer are also likely to become more widespread, abundant and active during warmer summers while refuges for reindeer/caribou on glaciers and late snow patches will probably disappear. 相似文献