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41.
Water samples were collected on a fortnightly basis in the lagoon of S. Gilla (Sardinia, Mediterranean Sea) in order to study seasonal nutritional fluctuations of particulate organic matter. the lagoon is characterized by high quantities of suspended matter throughout the year. Thermohaline conditions had no effect on particulate matter quantity and composition, but the quantity as well as quality of suspended particles was drastically affected by the wind, the major effecter of sediment resuspension. As a result of sediment resuspension, seston was always richer in inorganic fraction. However, throughout the year of investigation, most particulate organic carbon was quite appealing for filter feeding communities, although the best POM quality was available during phytoplankton blooming. the phytoplankton pool of suspended matter was just a small fraction of the bulk, accounting for only 13% on average of particulate organic carbon. in terms of energy available in the seston, the highest amount was stored in organic matter heterotrophic fraction, whilst the smallest was to be found in living phytoplankton.  相似文献   
42.
ABSTRACT

During policy change, the role of the actors communicating the change to different audiences is accentuated. The media plays an increasing role, either as an actor or by providing a stage for other actors. In particular, specialised journals represent an influential, albeit understudied, sphere of policy studies. We use the narrative policy framework complemented with frame analysis to trace how specialised media can affect policy implementation through implicit suggestions for action. Using this combined approach, we analyse how specialised forest journals, which are the most important forest information source for Finnish forest owners, have conveyed the renewal of forest legislation in Finland. The core message of the journals is that forest owners should, despite their new freedom granted by the reform, rely on experts rather than experimenting when managing their forests. This suggests that the media contributes to a path-dependent continuation of a forest policy that is based on a rationalistic exploitation ethos. The innovative potential, which the policy change aimed at encouraging, is thereby partially undermined. However, the analysis of the narratives also reveals that forest expertise and professionalism are diversifying. This notion is important as diversity can eventually lead to narratives supporting more fundamental change in forests management.  相似文献   
43.
Potassium-fly ash (K-FA) sorbents were investigated for high-temperature CO2 sorption. K-FAs were synthesised using coal fly ash as source of silica and aluminium. The synthesised materials were also mixed with Li2CO3 and Ca(OH)2 to evaluate their effect on CO2 capture. Temperature strongly affected the performance of the K-FA sorbents, resulting in a CO2 uptake of 1.45 mmol CO2/g sorbent for K-FA 1:1 at 700 °C. The CO2 sorption was enhanced by the presence of Li2CO3 (10 wt%), with the K-FA 1:1 capturing 2.38 mmol CO2/g sorbent at 700 °C in 5 min. This sorption was found to be similar to previously developed Li-Na-FA (2.54 mmol/g) and Li-FA (2.4 mmol/g) sorbents. The presence of 10 % Li2CO3 also accelerated sorption and desorption. The results suggest that the increased uptake of CO2 and faster reaction rates in presence of K-FA can be ascribed to the formation of K-Li eutectic phase, which favours the diffusion of potassium and CO2 in the material matrix. The cyclic experiments showed that the K-FA materials maintained stable CO2 uptake and reaction rates over 10 cycles.  相似文献   
44.
Ecosystem consequences of cyanobacteria in the northern Baltic Sea   总被引:1,自引:0,他引:1  
Cyanobacteria of the Baltic Sea have multiple effects on organisms that influence the food chain dynamics on several trophic levels. Cyanobacteria contain several bioactive compounds, such as alkaloids, peptides, and lipopolysaccharides. A group of nonribosomally produced oligopeptides, namely microcystins and nodularin, are tumor promoters and cause oxidative stress in the affected cells. Zooplankton graze on cyanobacteria, and when ingested, the hepatotoxins (nodularin) decrease the egg production of, for example, copepods. However, the observed effects are very variable, because many crustaceans are tolerant to nodularin and because cyanobacteria may complement the diet of grazers in small amounts. Cyanobacterial toxins are transferred through the food web from one trophic level to another. The transfer rate is relatively low in the pelagic food web, but reduced feeding and growth rates of fish larvae have been observed. In the benthic food web, especially in blue mussels, nodularin concentrations are high, and benthic feeding juvenile flounders have been observed to disappear from bloom areas. In the littoral ecosystem, gammarids have shown increased mortality and weakening of reproductive success under cyanobacterial exposure. In contrast, mysid shrimps seem to be tolerant to cyanobacterial exposure. In fish larvae, detoxication of nodularin poses a metabolic cost that is reflected as decreased growth and condition, which may increase their susceptibility to predation. Cyanobacterial filaments and aggregates also interfere with both hydromechanical and visual feeding of planktivores. The feeding appendages of mysid shrimps may clog, and the filaments interfere with prey detection of pike larvae. On the other hand, a cyanobacterial bloom may provide a refuge for both zooplankton and small fish. As the decaying bloom also provides an ample source of organic carbon and nutrients for the organisms of the microbial loop, the zooplankton species capable of selective feeding may thrive in bloom conditions. Cyanobacteria also compete for nutrients with other primary producers and change the nitrogen (N): phosphorus (P) balance of their environment by their N-fixation. Further, the bioactive compounds of cyanobacteria directly influence other primary producers, favoring cyanobacteria, chlorophytes, dinoflagellates, and nanoflagellates and inhibiting cryptophytes. As the selective grazers also shift the grazing pressure on other species than cyanobacteria, changes in the structure and functioning of the Baltic Sea communities and ecosystems are likely to occur during the cyanobacterial bloom season.  相似文献   
45.
During the last 50 years the practising and intensity of agriculture and forestry have differed considerably between Finnish and Russian Karelia. We studied the effects of different land use practices on the landscape composition in the two countries using the road transect sampling along four study routes (99-121 km) between 1997 and 1999. Effective environmental management in Finland has resulted in more distinct agricultural land types, more even distribution of the different age classes of forests, and the higher abundance of coniferous forests. Fields (mean percentage of the landscape: Finland 28%, Russia 13%), clearcuts and sapling stands (15%, 6%), and young forests (23%, 9%) were more typical elements of the Finnish landscape, whereas settlements (9%, 13%), semi-natural grasslands (3%, 7%), and mature forests (20%, 49%) were more characteristic of the Russian landscape. Landscape-level differences between the two countries may have various effects on the diversity of fauna and flora inhabiting Finnish and Russian Karelia.  相似文献   
46.
beta-Sitosterol is a weakly estrogenic phytosterol used extensively in functional foods to lower elevated serum cholesterol concentrations due to its inhibitory action on intestinal cholesterol absorption. It caused previously decreased sex steroid concentrations in fish and lowered sperm counts in rats. In the American mink (Neovison vison), litter size increased slightly due to dietary beta-sitosterol supplement. The aim of the present experiment was to conduct a dose-response study on the effects of beta-sitosterol on the reproduction of the American mink. Juvenile male and female mink (n=480) were exposed to 0, 5, 10 or 50 mg of peroral beta-sitosterol kg(-1)d(-1) for 10 months. After 3 months of exposure in November, 15 males per group were sacrificed and general biochemical variables reflecting overall health were determined. The beta-sitosterol-treated male mink had increased absolute and relative masses of intraabdominal fat and higher blood hemoglobin and serum high-density lipoprotein cholesterol concentrations. In spring, the top-rated male mink were mated with multiple females within each study group and reproductive success was assessed. No differences in the reproductive performance of the males (10-11 per group) or females (47-50 per group) could be detected in the exposed groups and the kits of all groups developed in a similar manner. The results suggest that dietary beta-sitosterol presents no significant risk to mammalian fertility.  相似文献   
47.
Biogenic volatile organic compound (BVOC) emissions are important in the global atmospheric chemistry and their feedbacks to global warming are uncertain. Global warming is expected to trigger vegetation changes and water table drawdown in boreal peatlands, such changes have only been investigated on isoprene emission but never on other BVOCs. We aimed at distinguishing the BVOCs released from vascular plants, mosses and peat in hummocks (dry microsites) and hollows (wet microsites) of boreal peatland microcosms maintained in growth chambers. We also assessed the effect of water table drawdown (?20 cm) on the BVOC emissions in hollow microcosms. BVOC emissions were measured from peat samples underneath the moss surface after the 7-week-long experiment to investigate whether the potential effects of vegetation and water table drawdown were shown. BVOCs were sampled using a conventional chamber method, collected on adsorbent and analyzed with GC–MS. In hummock microcosms, vascular plants increased the monoterpene emissions compared with the treatment where all above-ground vegetation was removed while no effect was detected on the sesquiterpenes, other reactive VOCs (ORVOCs) and other VOCs. Peat layer from underneath the surface with intact vegetation had the highest sesquiterpene emissions. In hollow microcosms, intact vegetation had the highest sesquiterpene emissions. Water table drawdown decreased monoterpene and other VOC emissions. Specific compounds could be closely associated to the natural/lowered water tables. Peat layer from underneath the surface of hollows with intact vegetation had the highest emissions of monoterpenes, sesquiterpenes and ORVOCs whereas water table drawdown decreased those emissions. The results suggest that global warming would change the BVOC emission mixtures from boreal peatlands following changes in vegetation composition and water table drawdown.  相似文献   
48.
The efforts in sustainable natural resource management have given rise to decentralization of forest governance in the developing world with hopes for better solutions and effective implementation. In this paper, we examine how spatially sensitive participation is realized from policy to practice in the process of establishing participatory forest management in Zanzibar, Tanzania. Our policy–practice analysis shows that the policies in Zanzibar strongly support decentralization and local level participation has in practice been realized. However, the policy does not emphasize participatory process design nor address the possibilities of using spatial information and technologies to ensure wider participation. Thus, the practices fall short in innovativeness of using site-sensitive information with available technologies. Reflecting the Zanzibari Community Forest Management Agreements (CoFMA) context with examples of participatory use of spatial information and technologies in other parts of the world, we discuss ways to improve the Zanzibari CoFMA process towards increased participation, communication, local sense of ownership and more sustainable land management decisions, and argue for the future implementation of CoFMA as a spatially sensitive participatory process.  相似文献   
49.
Early growth conditions, such as exposure to maternally derived androgens in bird eggs, have been shown to shape offspring in ways that may have important long-term consequences for phenotype and behavior. Using an experimental approach, we studied the long-term effects of yolk androgens on several phenotypic traits and parental behavior in adult and female collared flycatchers (Ficedula albicollis). We elevated yolk androgen levels and monitored the experimental recruits the following breeding seasons. Androgen treatment had a sex-dependent effect on adult body condition, yolk androgen-treated males being heavier than control males when controlling for size, a result which may be caused potentially by selective mortality, physiological differences, or different life-history strategies. Androgen treatment did not however affect the expression of sexually selected plumage ornaments (forehead and wing patch size), UV coloration, or parental feeding rate in either sex. Our results suggest that yolk androgens are unlikely to affect sexual selection via plumage characteristics or contribute to breeding success via altered parental care. Yolk androgens do not seem to act as a means for female collared flycatchers to enhance the attractiveness of their sons. The lower return rate previously observed for androgen-treated male offspring compared to controls may therefore not be due to lower mating or breeding success, but may rather reflect lower survival or higher dispersal propensity of yolk androgen-treated males.  相似文献   
50.
Industrial symbiosis (IS) studies the physical flows of materials and energy in local industrial systems using a systems approach. In this study the total fuel and energy use, and greenhouse gas emissions are calculated for an ‘industrial park’ operating in the same manner as an IS. Moreover the relevance of industrial symbiosis, particularly one centred on pulp and paper manufacturing, in moving towards more sustainable fuel consumption and reduced greenhouse gas emissions is discussed. The system is compared to hypothetical stand-alone production. Moreover, possibilities to reduce the energy use and total greenhouse gas emissions of the park are identified.  相似文献   
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