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Pfäffli P Hämeilä M Riala R Tornaeus J Wirmoila R 《Journal of environmental monitoring : JEM》2004,6(4):295-299
Methylhexahydrophthalic anhydride (MHHPA) is a hardener for hot-cured epoxy resins employed as insulators in the electric industry. MHHPA has only been measured as an ingredient with other alicyclic anhydrides, albeit there are also large processes which use only MHHPA. We collected MHHPA vapour in a set of devices: Teflon filter, glass spiral, TenaxTA tube connected consecutively together. Elution was performed with a solvent mixture of methyl-tert-butyl ether (70%), acetonitrile (30%), and acetic anhydride (0.5%). By capillary GC-ECD, the regression was linear (0.9994) in the practical low concentration range of 0.04-1 microg ml(-1) being equal to 0.001-0.035 mg m(-3) in 30 l of air. The exposure was measured in two factories manufacturing electric appliances. The assembled objects were first impregnated with a liquid epoxy/hardener mixture, and then the resin hardened at elevated temperature. In condenser manufacturing, the operators' 8 h exposure ranged from 0.068 to 0.118 mg m(-3), and the short-term exposure was during operation at ovens mean 1.90 mg m(-3). The impregnation of coiled resistors and transfer of them to ovens caused the worst exposures, short-term mean 3.846 mg m(-3) and long-term mean 2.191 mg m(-3). During the 'baking', the ovens were closed and evacuated, but when the hot objects were moved out of the ovens, they continued during chilling to emit MHHPA, mean 0.366 mg m(-3). In the adjacent areas, assembling, control rooms, offices, the exposure was still significant, 0.017-0.043 mg m(3), due to leaks from the high exposure areas. Mechanical general ventilation and local exhausts were functioning. Respirators were available for short supervising of the hot equipment. 相似文献
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Analyzing and predicting the development of foliar nutrient concentrations are important and challenging tasks in environmental monitoring. This article presents how linear sparse regression models can be used to represent the relations between different foliar nutrient concentration measurements of coniferous trees in consecutive years. In the experiments the models proved to be capable of providing relatively good and reliable predictions of the development of foliage with a considerably small number of regressors. Two methods for estimating sparse models were compared to more conventional linear regression models. Differences in the prediction accuracies between the sparse and full models were minor, but the sparse models were found to highlight important dependencies between the nutrient measurements better than the other regression models. The use of sparse models is, therefore, advantageous in the analysis and interpretation of the development of foliar nutrient concentrations. 相似文献
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Tatsuro Nakaji Takuya Kobayashi Mihoko Kuroha Kumiko Omori Yuko Matsumoto Tetsushi Yonekura Katsuhiko Watanabe Jarkko Utriainen Takeshi Izuta 《Water, Air, & Soil Pollution: Focus》2004,4(2-3):277-287
To evaluate the effect of increasing nitrogen (N) deposition and tropospheric ozone (O3) concentrations on N-saturated forest ecosystems, we investigated the response of Japanese red pine (Pinus densiflora), an N-saturation sensitive tree species, to increasing N load under elevated O3 concentrations. One-year-old seedlings of red pine were treated with three levels of N supply (0, 50 and 100 mg N L-1 fresh soil volume) under two levels of atmospheric O3 concentration (< 5 and 60 ppb) for two growing seasons. Nitrogen treatment did not stimulate dry matter production of the seedlings. Growth inhibition was observed in the highest N treatment under low O3 and in the two higher N treatments under elevated O3. Irrespective of the O3 concentration, increasing N supply negatively affected root growth and mycorrhizal development in fine roots, resulting in a reduction in P and Mg uptake from the soil. Net photosynthetic rate was significantly reduced by both the highest N treatment under low O3 and the two higher N treatments under elevated O3, together with decreased N-availability to Rubisco. Nitrogen assimilated from NO3 - to amino acid in the needles was not affected by the treatments. However, needle protein concentration was reduced by the highest N-treatment under low O3 and by the two higher N-treatments under elevated O3. These results suggest that elevated O3 potentially disturbs the N-availability in the form of protein including Rubisco, and may advance the negative effects of excessive N-deposition on N-sensitive plant species in N-saturated forests. 相似文献
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Anttila A Leppänen AP Rissanen K Ylipieti J 《Journal of environmental radioactivity》2011,102(7):659-666
Samples of summer pasture plants that reindeer feed on were collected in order to study 137Cs concentrations in different plant species and in species nested in certain site types, and to study the regional distribution of 137Cs in the Finnish reindeer management area. Plant species were categorized by the site types of mineral soil forest (xeric heath forest and mesic heath forest) and peatland. A third category called ’other plant species’ included plants with various site types, poorly determined species and species with poor statistics. The 137Cs concentrations in different site types differed significantly. The mean 137Cs concentrations of the whole reindeer management area in the xeric heath forest plant species was 44 ± 27 Bq/kg dw, in the mesic heath forest plant species 75 ± 59 Bq/kg dw and in the peatland plant species 219 ± 150 Bq/kg dw. The peatland species uptake 137Cs more efficiently than plant species of mineral soil forests. A particularly efficient collector of 137Cs was Trichophorum sp. It is suggested that Trichophorum sp. could be used as an indicator species for reindeer summer fodder plants. The highest concentrations of 137Cs were found in Southern Lapland and the lowest in Northern Lapland. Today, the concentrations of 137Cs in summer pasture plants that reindeer feed on in Finland are at such a level that there is no need to avoid any plant species. In the case of future nuclear fallout, reindeer grazing in peatlands would increase concentrations of 137Cs in reindeer meat. 相似文献
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Dissolved organic matter from natural sources (DNOM) is omnipresent in aquatic ecosystems. Besides affecting bioavailability of substances including xenobiotics, it directly influences physico-chemistry of the habitat and there is increasing evidence for it is interaction with organisms. We investigated direct and interacting effects of DNOM from three sources, Lake Valkea-Kotinen, Svartberget Brook, and Lake Fuchskuhle with the herbicide paraquat on the oligochaete worm Lumbriculus variegatus. Bioavailability of paraquat to L. variegates as well as activities of antioxidative enzymes catalase (CAT) and peroxidase (POD) and biotransformation enzyme soluble glutathione S-transferase (sGST) were assessed without and in the presence of DNOM. Furthermore, metabolic heat dissipation due to the exposure was quantified. Uptake of paraquat into the worms was concentration dependently reduced by DNOM, and with differences concerning the DNOM sources. sGST and CAT responded with increased activities to DNOM (5 and 25 mg C l-1) and paraquat (5.0, 50, and 500 microg l-1) separately. Paraquat at 5.0 microg l-1 and DNOM in combination caused increased activities of sGST, especially at 5 mgC l-1, but inhibition of CAT activities. The latter probably occurred due to saturation of the enzyme. Changes in enzyme activities were independent from the source of DNOM. Increasing DNOM concentrations raised metabolic heat dissipation in L. variegatus with maximum at 3h of exposure. In the combined treatments, metabolic heat dissipation changed more due to the source of DNOM than due to the bioavailability of paraquat. 相似文献
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Jarkko V. Niemi Sanna Saarikoski Minna Aurela Heikki Tervahattu Risto Hillamo Douglas L. Westphal Päivi Aarnio Tarja Koskentalo Ulla Makkonen Hanna Vehkamäki Markku Kulmala 《Atmospheric environment (Oxford, England : 1994)》2009,43(6):1255-1264
The frequency, strength and sources of long-range transport (LRT) episodes of fine particles (PM2.5) were studied in southern Finland using air quality monitoring results, backward air mass trajectories, remote sensing of fire hot spots, transport and dispersion modelling of smoke and chemical analysis of particle samples (black carbon, monosaccharide anhydrides, oxalate, succinate, malonate, SO42?, NO3?, K+ and NH4+). At an urban background site in Helsinki, the daily WHO guideline value (24-h PM2.5 mean 25 μg m?3) was exceeded during 1–7 LRT episodes per year in 1999–2007. The 24-h mean maximum concentrations varied between 25 and 49 μg m?3 during the episodes, which was 3–6 times higher than the local mean concentration (8.7 μg m?3) in 1999–2007. The highest particle concentrations (max. 1-h mean 163 μg m?3) and the longest episodes (max. 9 days) were mainly caused by the emissions from open biomass burning, especially during springs and late-summers in 2002 and 2006. During the period 2001–2007, the satellite remote sensing of active fire hot spots and transport and dispersion modelling of smoke indicated that approximately half of the episodes were caused partly by the emissions from wildfires and/or agricultural waste burning in fields in Eastern Europe, especially in Russia, Belarus and Ukraine. Other episodes were mainly caused by the LRT of ordinary anthropogenic pollutants, e.g. from energy production, traffic, industry and wood combustion. During those ‘other episodes’, air masses also arrived from Eastern Europe, including Poland. The highest concentrations of biomass-burning tracers, such as monosaccharide anhydrides (levoglucosan + mannosan + galactosan) and K+, were observed during open biomass-burning episodes, but quite high values were also measured during some winter episodes due to wood combustion emissions. Our results indicate that open biomass burning in Eastern Europe causes high fine particle concentration peaks in large areas of Europe almost every year. 相似文献
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Dissolved organic matter in pore water of freshwater sediments: effects of separation procedure on quantity, quality and functionality 总被引:2,自引:0,他引:2
Pore water was separated either with or without water extraction prior to centrifugation (7600 or 20 000 × g) in order to investigate the effects of separation procedure on the amount and properties of dissolved organic matter (DOM i.e. the material passing through a 0.45-μm filter) in three freshwater sediments. On the basis of solubility in alkaline, organic matter was concluded to compose of humic substances in two (S1 and S3) and of humin (S2) in one of the sediments. DOM in the samples was quantified by total organic carbon measurement. Specific UV-absorption (SUVA) and high performance size exclusion chromatography (HPSEC) analyses were used to characterize DOM. Sorption of pyrene was used as a measure for functionality of DOM. Both water extraction and centrifugation speed were shown to affect the properties of DOM; however, the effects were sediment dependent. Water extraction increased the amount of DOM separated from the two sediments that had humic character (S1 and S3). In most cases water extraction increased SUVA and shifted the molecular size distribution of DOM towards larger sizes. The separation procedure had also an effect on the functionality of DOM. In water extracted samples of S2 and S3 the sorption of pyrene was higher than in the corresponding samples separated without water extraction, whereas in S1 similar effect was not found. Generally, centrifugation speed had smaller effects on the properties of DOM than water extraction. The fact that the effects of separation procedure on DOM depend on the sediment characteristics complicates the comparison between samples and evaluation of functionality in field conditions. 相似文献
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The aim of the present work was to systematically study the effect of low concentrations of dissolved organic matter (DOM) on the bioconcentration of organic contaminants, in order to show whether the phenomenon of enhanced bioconcentration factors (BCFs), that has been reported in the literature, is generally found at low levels of DOM or if BCF enhancements are more likely due to a random scatter in the experimental data. The first part of the study tested the hypothesis that low levels of DOM affect the uptake kinetics of organic contaminants, leading to transient enhancements of BCFs, relative to DOM-free controls, which could have been reported as BCF enhancements in short-term studies. We found that the presence of low concentrations of two different types of DOM consistently decreased the bioconcentration of benzo[a]pyrene (BaP) in the water flea Daphnia magna at all exposure times (1-24 h), and that no transient BCF enhancements occurred. The second part of the study systematically investigated if low concentrations of DOM from a wide range of different aquatic systems can cause enhancements in the bioconcentration of organic contaminants. Water fleas were exposed to combinations of four different organic contaminants (BaP, tetrachlorobiphenyl, pentachlorophenol and naphthalene) with low concentrations of 12 different types of DOM that had been collected from various regions throughout Europe. In several of the DOM treatments, we found mean BCFs being higher than mean BCFs in the controls (especially for naphthalene). This shows that the experimental setup used in this study (and similarly in previous studies) can produce seeming BCF enhancements at low concentrations of DOM. However, statistical analyses showed that treatment means were not significantly different from control means. Thus, this systematic study suggests that the BCF enhancements that have been reported in the literature are more likely the result of random, experimental variations than the result of a systematic enhancement of bioconcentration. 相似文献
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Jesús M. Avilés Jarkko Rutila Anders Pape Møller 《Behavioral ecology and sociobiology》2005,58(6):608-617
Hole-nesting habits of redstarts Phoenicurus phoenicurus make laying difficult for parasitic cuckoo Cuculus canorus females and eviction of host eggs difficult for the cuckoo hatchling, causing fitness costs of cuckoo parasitism to be lower than those reported for open nesting hosts. Redstarts have recognition problems when confronted with real cuckoo eggs showing a perfect mimicry with their own eggs since they never eject when parasitized with perfect mimetic cuckoo eggs but instead desert the nest. Here we use a cost-benefit model to assess the effects of parasitism costs and the probability of being parasitized to estimate the reproductive success of redstarts when accepting or rejecting in the presence or absence of parasitism. Baseline data for model calculations come from this and a previous study on a cuckoo parasitized redstart population in Finland. When desertion implies a loss of 50%, we found that below a threshold value of 20% parasitism redstarts should accept cuckoo eggs since the costs of rejection exceed the benefits, whereas above this threshold they should reject. Interestingly, as the cost of desertion increases the threshold value, it should pay the redstart to reject increasingly at an exponential rate. Our field observations on natural parasitism and experiments with artificial cuckoo eggs confirmed the predictions from the model when hatching failures of the cuckoo were taken into account. Therefore, the low cost imposed by cuckoo parasitism in the system, and the presumably high cost of desertion as a response to parasitism favours acceptance over rejection for a wide range of parasitism pressures. This finding could explain the low rejection rate of real cuckoo eggs found in the redstart despite the presumably long history of a coevolutionary relationship with the cuckoo in Finland. 相似文献