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11.
An experiment combining the use of two ecosystem models was conducted to search for effective protection strategies for the Gulf of Finland (Baltic Sea). Reference and scenario simulations were first run with a one-dimensional (1D) model for seven main basins of the entire Baltic Sea until steady state was achieved. The obtained basinwise distributions of inorganic nitrogen (N) and phosphorus (P), as well as sediment labile P, were then used to initiate 5-y simulations with a three-dimensional (3D) ecosystem model. The results suggest that relatively small local load reductions (the "Finland" scenario) would improve only the state of adjacent coastal waters significantly. This would be the case, even for runs covering several decades, which clearly exceed the residence times of nutrients in the Gulf of Finland. A significant decrease from a substantial loading source to the Gulf (the "St. Petersburg" scenario) would decrease cyanobacterial biomasses in the entire Gulf of Finland and also immediately outside it. A reduction in the current Polish nutrient loads would improve the situation in the whole Baltic Proper and cause an extensive decline in cyanobacterial biomasses in the Gulf of Finland, as well. However, it would take several decades until the improvement caused by reducing loads in the "Poland" scenario is seen, while in the "St. Petersburg" scenario the corresponding time lag would only be a few years. Our results suggest that the common water protection policy in the Baltic Sea region should have the largest nutrient sources as its primary target, regardless of their location and country. 相似文献
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The great majority of genetic defects underlying steroid 21-hydroxylase deficiency appear to result from intergenic recombinations between the homologous CYP21 and CYP21P genes. For a minority, novel sporadic point mutations have been detected. De novo mutations in CYP21 have also been reported, but only a few studies have systematically screened their occurrence. We here describe a population-based patient sample in order to estimate the rate of single-family (i.e. sporadic) and de novo germline mutations in the human CYP21 locus. Among 76 Finnish families were observed three single-family mutations and two de novo mutations in CYP21. The rates obtained, ∼5% and ∼2% for novel and de novo mutations, respectively, indicate that they are not rare and that their occurrence should not be ignored in genetic diagnostics of this disorder. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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Rasilainen K Suksi J Ruskeeniemi T Pitkänen P Poteri A 《Journal of contaminant hydrology》2003,61(1-4):235-246
Uranium release observed in a rock matrix around water-carrying fractures was studied using U-series disequilibrium (USD) modelling and mass balance calculations. Several release scenarios were tested, with specific attention to the glacial aspects. The release appears to have occurred in two or three violent episodes during the last 300 ky. A release after the last glaciation can be excluded on mass flow grounds. Continuous release for more than 300 ky can be excluded on radioactive disequilibrium grounds. Repeated inflows of oxic glacial meltwater seem to have triggered the release episodes. 相似文献
16.
Genetic Diversity, Population Size, and Fitness in Central and Peripheral Populations of a Rare Plant Lychnis viscaria 总被引:1,自引:0,他引:1
Abstract: Genetic diversity is expected to decrease in small and isolated populations as a consequence of bottlenecks, founder effects, inbreeding, and genetic drift. The genetics and ecology of the rare perennial plant Lychnis viscaria (Caryophyllaceae) were studied in both peripheral and central populations within its distribution area. We aimed to investigate the overall level of genetic diversity, its spatial distribution, and possible differences between peripheral and central populations by examining several populations with electrophoresis. Our results showed that the level of genetic diversity varied substantially among populations ( H exp = 0.000–0.116) and that the total level of genetic diversity (mean H exp = 0.056) was low compared to that of other species with similar life-history attributes. The peripheral populations of L. viscaria had less genetic variation (mean H exp = 0.034) than the central ones (0.114). Analysis of genetic structure suggested limited gene flow (mean F ST = 0.430) and high differentiation among populations, emphasizing the role of genetic drift ( N e m = 0.33). Isolation was even higher than expected based on the physical distance among populations. We also focused on the association between population size and genetic diversity and possible effects on fitness of these factors. Population size was positively correlated with genetic diversity. Population size and genetic diversity, however, were not associated with fitness components such as germination rate, seedling mass, or seed yield. There were no differences in the measured fitness components between peripheral and central populations. Even though small and peripheral populations had lower levels of genetic variation, they were as viable as larger populations, which emphasizes their potential value for conservation. 相似文献
17.
Pertti Ranta § Antti Tanskanen † Jari Niemelä and Arto Kurtto‡ 《Conservation biology》1999,13(6):1293-1300
Abstract: The occurrence of vascular plants was surveyed on 207 islands (size range 0.01–390.2 ha, number of plant species 1–449) offshore from the city of Helsinki in the Baltic Sea to examine the conservation value of these islands. We calculated a rarity score for each species (1/number of islands occupied by the species) and a biodiversity score for each island (sum of the rarity scores of each species present on the island). Positive correlations between species number and biodiversity score (r s = 0.97, p < 0.001) and between biodiversity score and island area (r s = 0.87, p < 0.001) indicated that these parameters are heavily dependent on island size. With the goal of including at least one occurrence (island) of all plant species, an iterative selection algorithm chose a set of 41 islands whose average size (29.3 ha) was four times the average size of all existing islands (7.0 ha). Strong nestedness ( N < 54) explains the concentration of plant species diversity on large islands. An operational strategy for selection of sites for protection is to complement the set produced by a selection algorithm with target species not yet included (e.g., endangered species with several occurrences). Comprehensive mapping and analysis of a taxonomic group will help integrate conservation biology into land-use planning and increase the quality of the networks of protected areas. 相似文献
18.
Jaakko Paasivirta Hannu Hakala Juha Knuutinen Terttu Otollinen Jukka Srkk Leena Welling Raija Paukku Reino Lammi 《Chemosphere》1990,21(12):1355-1370
Chlorohydrocarbons and free and chemically bound chlorophenols, catechols and guaiacols were measured from lake sediments in Central Finland. Chlorohydrocarbons occurred at low backround levels except chlorocymenes from pulp mills and PCBs near the city of Äänekoski, where a local leakage occurrs. Free chlorophenols (hexane extractables) were found in all 18 areas studied, but the bound ones (extracted with strong alkali) only in the pulp mill reciepient lakes where they dominated. Preliminary analyses of chemically bound chlorophenols in high molecular fractions of spent bleach liquors and pulp mill effluents indicated that majority of chlorocatechols and guaiacols are bound already in the factory. 相似文献
19.
Kari Rasilainen Juhani Suksi Timo Ruskeeniemi Petteri Pitknen Antti Poteri 《Journal of contaminant hydrology》2003,61(1-4):235
Uranium release observed in a rock matrix around water-carrying fractures was studied using U-series disequilibrium (USD) modelling and mass balance calculations. Several release scenarios were tested, with specific attention to the glacial aspects. The release appears to have occurred in two or three violent episodes during the last 300 ky. A release after the last glaciation can be excluded on mass flow grounds. Continuous release for more than 300 ky can be excluded on radioactive disequilibrium grounds. Repeated inflows of oxic glacial meltwater seem to have triggered the release episodes. 相似文献
20.
Juha Einola Kai Sormunen Anssi Lensu Antti Leiskallio Matti Ettala Jukka Rintala 《Waste management (New York, N.Y.)》2009,29(7):2105-2120
Methane oxidation was studied at a closed boreal landfill (area 3.9 ha, amount of deposited waste 200,000 tonnes) equipped with a passive gas collection and distribution system and a methane oxidative top soil cover integrated in a European Union landfill directive-compliant, multilayer final cover. Gas wells and distribution pipes with valves were installed to direct landfill gas through the water impermeable layer into the top soil cover. Mean methane emissions at the 25 measuring points at four measurement times (October 2005–June 2006) were 0.86–6.2 m3 ha?1 h?1. Conservative estimates indicated that at least 25% of the methane flux entering the soil cover at the measuring points was oxidized in October and February, and at least 46% in June. At each measurement time, 1–3 points showed significantly higher methane fluxes into the soil cover (20–135 m3 ha?1 h?1) and methane emissions (6–135 m3 ha?1 h?1) compared to the other points (<20 m3 ha?1 h?1 and <10 m3 ha?1 h?1, respectively). These points of methane overload had a high impact on the mean methane oxidation at the measuring points, resulting in zero mean oxidation at one measurement time (November). However, it was found that by adjusting the valves in the gas distribution pipes the occurrence of methane overload can be to some extent moderated which may increase methane oxidation. Overall, the investigated landfill gas treatment concept may be a feasible option for reducing methane emissions at landfills where a water impermeable cover system is used. 相似文献