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11.
The sediments and various organisms in Lake Päijänne were examined for contaminants. The average mercury content of water plants was 9, of plankton 14, of sediment 114, of zoobenthic predators 83, of fish 332–1510 and of birds 240–13685 μg kg−1 (wet weight). The average PCB content of plants was 3, of plankton 21, of the zoobenthos 44, of fish 36-117 and of birds 219–13490 μg kg−1 . The average ΔDDT content of plants was 0.5, of plankton 6, of the zoobenthos 14, of fish 7–42 and of birds 144-8262 μg kg−1 . Regional differences in mercury content were most pronounced in sediment and fish. PCB concentration was highest near a town. ΔDDT was quite evenly distributed. Water plant species did not differ from each other, nor did the plankton fractions. The zoobenthic predators contained more chlorinated hydrocarbons than did the herbivores. There were clear differences between most species of fish and the chlorinated hydrocarbon content was highest in vendace. In adult birds levels of all residues were significantly higher than in juveniles.
In most cases PCB content was positively correlated with ΔDDT and in birds PCB, ΔDDT and mercury levels were correlated. DDT residues occurred mostly as DDE, but in vendace the proportion of DDT was high. At most trophic levels, ΔDDT/PCB was 0.15-0.40 but in birds it reached 1–2. 相似文献
In most cases PCB content was positively correlated with ΔDDT and in birds PCB, ΔDDT and mercury levels were correlated. DDT residues occurred mostly as DDE, but in vendace the proportion of DDT was high. At most trophic levels, ΔDDT/PCB was 0.15-0.40 but in birds it reached 1–2. 相似文献
12.
James E. Jumblatt Tien-Wen Tao Verena Schlup Jukka Finne Max M. Burger 《Biochemical and biophysical research communications》1980,95(1):111-117
Variants of B 16-F 1 mouse melanoma cells selected for resistance to wheat germ agglutinin (WGA) toxicity were found to have undergone a stable surface change correlated both to lectin resistance and reduced metastasizing potential. The surface alteration, as indicated by the increased electrophoretic mobilities of several lactoperoxidase-iodinated cell surface proteins in SDS-PAGE, was restricted to polypeptides able to interact with WGA. The availability of lectin-resistant melanoma cell variants having altered metastasizing behavior provides a promising approach to studies of the role of specific cell surface components in the metastasizing process. 相似文献
13.
14.
The derivatives obtained by per-methylation of unsubstituted 2-amino-2-deoxy-hexitols and of these compounds monosubstituted at C-3. C-4, or C-6, and disubstituted at C-3 and C-6, have been analysed by g.l.c.-m.s. Each derivative can be identified on the basis of retention time and mass spectrum. In methylation analysis, methanolysis gave one derivative of each hexitol, whereas a mixture of products was formed when degradation was effected by acetolysis followed by hydrolysis. An application in the analysis of amino-sugar linkages in alkali-labile O-glycosylic oligosaccharides from rat-brain glycoproteins is described. 相似文献
15.
The site of substitution of the peripheral branches on the core mannose-residues in the complex-type carbohydrate units of glycoproteins has been studied by Smith degradation. By using glycopeptides of known structure, it is shown that the site of attachment of the (1→4)-linked, third branch to the mannose core in tri- and tetra-antennary structures may be conveniently demonstrated by this technique. A critical factor was found to be the concentration of acid used for cleavage of the periodate-oxidized product. This finding could explain discrepancies concerning the previously published structures of fetuin glycopeptides. The technique was applied for study of the branching pattern in human transferrin, porcine thyroglobulin, and rat plasma and brain glycoproteins. The results support the concept that, in glycoproteins from most sources, the third (1→4)-linked branch is attached to the (1→3)-linked mannose residue of the core portion in the complex-type structures. An indication for a novel type of branching pattern in human transferrin was, however, also obtained. 相似文献
16.
S. Saarnio Jukka Alm Jouko Silvola Annalea Lohila Hannu Nykänen Pertti J. Martikainen 《Oecologia》1997,110(3):414-422
Temporal and spatial variation in CH4 emissions was studied at hummock, Eriophorum lawn, flark and Carex lawn microsites in an oligotrophic pine fen over the growing season using a static chamber method, and CH4 production and oxidation potentials in peat profiles from hummock and flark were determined in laboratory incubation experiments.
Emissions were lowest in the hummocks, and decreased with increasing hummock height, while in the lawns and flarks they increased
with increasing sedge cover. Statistical response functions with water table and peat temperature as independent variables
were calculated in order to reconstruct seasonal CH4 emissions by reference to the time series for peat temperature and water table specific to each microsite type. Mean CH4 emissions in the whole area in the snow-free period of 1993, weighted in terms of the proportions of the microsites, were
1.7 mol CH4 m–2. Potential CH4 production and oxidation rates were very low in the hummocks rising above the groundwater table, but were relatively similar
when expressed per dry weight of peat both in the hummocks and flarks below the water table. The CH4 production potential increased in autumn at both microsites and CH4 oxidation potential seemed to decrease. The decrease in temperature in autumn certainly reduced in situ decomposition processes,
possibly leaving unused substrates in the peat, which would explain the increase in CH4 production potential.
Received: 16 August 1996 / Accepted: 30 November 1996 相似文献
17.
Marja Maljanen Narasinha Shurpali Jyrki Hyt?nen P?ivi M?kiranta Lasse Aro Hannamaria Potila Jukka Laine Changsheng Li Pertti J. Martikainen 《Biogeochemistry》2012,108(1-3):199-218
Pristine peatlands have generally low nitrous oxide (N2O) emissions but drainage and management practices enhance the microbial processes and associated N2O emissions. It is assumed that leaving peat soils from intensive management, such as agriculture, will decrease their N2O emissions. In this paper we report how the annual N2O emission rates will change when agricultural peat soil is either left abandoned or afforested and also N2O emissions from afforested peat extraction sites. In addition, we evaluated a biogeochemical model (DNDC) with a view to explaining GHG emissions from peat soils under different land uses. The abandoned agricultural peat soils had lower mean annual N2O emissions (5.5?±?5.4?kg?N?ha?1) than the peat soils in active agricultural use in Finland. Surprisingly, N2O emissions from afforested organic agricultural soils (12.8?±?9.4?kg?N?ha?1) were similar to those from organic agricultural soils in active use. These emissions were much higher than those from the forests on nutrient rich peat soils. Abandoned and afforested peat extraction sites emitted more N2O, (2.4?±?2.1?kg?N?ha?1), than the areas under active peat extraction (0.7?±?0.5?kg?N?ha?1). Emissions outside the growing season contributed significantly, 40% on an average, to the annual emissions. The DNDC model overestimated N2O emission rates during the growing season and indicated no emissions during winter. The differences in the N2O emission rates were not associated with the age of the land use change, vegetation characteristics, peat depth or peat bulk density. The highest N2O emissions occurred when the soil C:N ratio was below 20 with a significant variability within the measured C:N range (13–27). Low soil pH, high nitrate availability and water table depth (50–70?cm) were also associated with high N2O emissions. Mineral soil has been added to most of the soils studied here to improve the fertility and this may have an impact on the N2O emissions. We infer from the multi-site dataset presented in this paper that afforestation is not necessarily an efficient way to reduce N2O emissions from drained boreal organic fields. 相似文献
18.
Sanna Saarnio Jukka Alm Pertti J. Martikainen & Jouko Silvola 《Journal of Ecology》1998,86(2):261-268
1 In a glasshouse experiment we studied the effect of raised CO2 concentration (720 p.p.m.) on CH4 emission at natural boreal peat temperatures using intact cores of boreal peat with living vascular plants and Sphagnum mosses. After the end of the growing season half of the cores were kept unnaturally warm (17–20 °C). The potential for CH4 production and oxidation was measured at the end of the emission experiment.
2 The vascular cores ('Sedge') consisted of a moss layer with sedges, and the moss cores (' Sphagnum ') of Sphagnum mosses (some sedge seedlings were removed by cutting). Methane efflux was 6–12 times higher from the Sedge cores than from the Sphagnum cores. The release of CH 4 from Sedge cores increased with increasing temperature of the peat and decreased with decreasing temperature. Methane efflux from Sphagnum cores was quite stable independent of the peat temperatures.
3 In both Sedge and Sphagnum samples, CO2 treatment doubled the potential CH4 production but had no effect on the potential CH4 oxidation. A raised concentration of CO2 increased CH4 efflux weakly and only at the highest peat temperatures (17–20 °C).
4 The results suggest that in cool regions, such as boreal wetlands, temperature would restrict decomposition of the extra substrates probably derived from enhanced primary production of mire vegetation under raised CO2 concentrations, and would thus retard any consequent increase in CH4 emission. 相似文献
2 The vascular cores ('Sedge') consisted of a moss layer with sedges, and the moss cores (' Sphagnum ') of Sphagnum mosses (some sedge seedlings were removed by cutting). Methane efflux was 6–12 times higher from the Sedge cores than from the Sphagnum cores. The release of CH
3 In both Sedge and Sphagnum samples, CO
4 The results suggest that in cool regions, such as boreal wetlands, temperature would restrict decomposition of the extra substrates probably derived from enhanced primary production of mire vegetation under raised CO
19.
Spatial variation in infection by digenetic trematodes in a population of freshwater snails (Potamopyrgus antipodarum) 总被引:2,自引:0,他引:2
Larval digenetic trematodes commonly castrate their first intermediate hosts, and should therefore impose strong selection on the timing and mode of host reproduction. Here we examine spatial variation in infection by trematodes in the freshwater snail Potamopyrgus antipodarum. Snails were collected at 11 different sites at Lake Alexandrina on the South Island of New Zealand from transects that ran perpendicular to the shore and across several different habitat types (from 0 to 8 m deep). Logistic regression was used to analyze the relationships between the frequency of trematode infection and snail size, habitat type, and transect location. On average, the probability of infection increased 3.3 times with each 1 mm increase in shell length. Prevalence of infection by the most common species of trematode, Microphallus sp., was highest in the shallow-water habitats where its final hosts (waterflow) spend most of their time. Prevalence of infection by another parasite, Telogaster ophistorchis (final host: eels) increased with depth, but because Microphallus was much more common, total infection by all trematodes decreased with depth. The effects of transect location were minor for Telogaster, but there was significant variation in Microphallus prevalence among transects, especially in the shore-bank habitat. Taken together, these results suggest that the risk of infection is spatially variable, but generally higher in shallow-water habitats, which may explain the greater frequency of sexual individuals as well as earlier reproduction among individuals near shore. 相似文献
20.
Jukka Kekäläinen Geir Rudolfsen Matti Janhunen Lars Figenschou Nina Peuhkuri Niina Tamper Raine Kortet 《BMC evolutionary biology》2010,10(1):20