排序方式: 共有39条查询结果,搜索用时 234 毫秒
31.
Kuparinen J Kuosa H Andersson A Autio R Granskog MA Ikävalko J Kaartokallio H Karell K Leskinen E Piiparinen J Rintala JM Tuomainen J 《Ambio》2007,36(2-3):149-154
This paper compiles biological and chemical sea-ice data from three areas of the Baltic Sea: the Bothnian Bay (Hailuoto, Finland), the Bothnian Sea (Norrby, Sweden), and the Gulf of Finland (Tv?rminne, Finland). The data consist mainly of field measurements and experiments conducted during the BIREME project from 2003 to 2006, supplemented with relevant published data. Our main focus was to analyze whether the biological activity in Baltic Sea sea-ice shows clear regional variability. Sea-ice in the Bothnian Bay has low chlorophyll a concentrations, and the bacterial turnover rates are low. However, we have sampled mainly land-fast level first-year sea-ice and apparently missed the most active biological system, which may reside in deformed ice (such as ice ridges). Our limited data set shows high concentrations of algae in keel blocks and keel block interstitial water under the consolidated layer of the pressure ridges in the northernmost part of the Baltic Sea. In land-fast level sea-ice in the Bothnian Sea and the Gulf of Finland, the lowermost layer appears to be the center of biological activity, though elevated biomasses can also be found occasionally in the top and interior parts of the ice. Ice algae are light limited during periods of snow cover, and phosphate is generally the limiting nutrient for ice bottom algae. Bacterial growth is evidently controlled by the production of labile dissolved organic matter by algae because low growth rates were recorded in the Bothnian Bay with high concentrations of allochthonous dissolved organic matter. Bacterial communities in the Bothnian Sea and the Gulf of Finland show high turnover rates, and activities comparable with those of open water communities during plankton blooms, which implies that sea-ice bacterial communities have high capacity to process matter during the winter period. 相似文献
32.
Nicolas F. Ponchaut Harri K. Kytömaa Delmar R. Morrison Melissa K. Chernovsky 《Journal of Loss Prevention in the Process Industries》2011,24(6):870-878
The recent publication of evaluation protocols for vapor source term models and vapor dispersion models have influenced the modeling approaches that can be used for approval of new and expansion projects at LNG receiving terminals. In the past few years the scientific basis of integral vapor source term models has been questioned with growing concerns regarding their validity. In this paper, the shallow water equations (SWEs) were solved to study the characteristics of the evaporating LNG pool associated with a constant flow rate spill of LNG into a concrete sump. In the early stages of pool spreading, the leading edge thickness profile of the SWE model scales with the square root of the distance from the leading edge as the pool spreads. After the edge of the pool reaches the wall, the reflected wave forms a hydraulic jump that travels back towards the center of the pool at a speed that is considerably slower than the initial spreading of the pool. Once the hydraulic jump reaches the center, the pool assumes a nearly flat free surface for the rest of the spill. The pool spreading and the rate of evaporation from the SWEs were then compared to the solution provided by the integral model, PHAST. The two approaches were found to agree well with one another. The SWE model was also used to demonstrate the influence of an elevated spill source. With an elevated source, the LNG pool spreads faster, significantly increasing the initial rate of vaporization and peak vaporization rate. This increase in the initial rate of vaporization could lead to an increase in the vapor cloud hazard distance. The SWE model was also used to demonstrate the influence of an inclined sump floor in the shape of an inverted cone where the spilling LNG accumulates in the low vertex of the cone. Inclined sump floors can be used to significantly reduce the cumulative evaporation, making them attractive as a possible mitigation approach in cases where a containment sump is located close to a property boundary. 相似文献
33.
A simulation procedure for the calculation of temperature, cloudiness, radiation, precipitation, air humidity, windiness and atmospheric carbon is presented. The procedure generates the hourly or daily values of the weather factors based on long-term weather statistics. The basic factor behind the weather pattern indicated by different weather factors is air temperature, which modifies the cloudiness produced by a stochastic process in other respects. Consequently, the radiation and precipitation coming onto a site and the air humidity are also modified by temperature. This facilitates the future weather patterns to be calculated on the basis of the temperature increase allowing to introduce the effect of the suggested climatic change also into the other weather factors, assuming that the basic variability of the weather factors remains unchanged. The future windiness is calculated as random process without correlation to other weather factors. 相似文献
34.
Kalevi M. Korpela Matti Ylén Liisa Tyrväinen Harri Silvennoinen 《Journal of environmental psychology》2009
We investigated the reliability and stability of favourite place selections and evaluations of place attachment over a 10-month period. A simple random sample of 1273 respondents representative of the population of the two largest cities in Finland completed a mailed questionnaire. Reliability data was obtained in a second questionnaire (N = 427). We obtained five main favourite place types which were extensively managed natural settings (mainly urban woodlands), urban green spaces (mostly parks), waterside environments, exercise and activity/hobby areas, and indoor and outdoor urban areas. Sixty-four percent of the respondents in the second survey selected the same main favourite place type as 10 months earlier, which is more than what might be expected by chance. Extensively managed natural settings (mainly urban woodlands) and waterside environments were reselected most often. Indoor and outdoor urban favourite places had the lowest stability. We found evidence of people being more consistent in their attachment to natural favourite places than to urban favourite places. The findings lend further credence and credibility to earlier results concerning self-regulation and restorative experiences in favourite places. 相似文献
35.
Olli Manilla Tari Haahtela Harri Vaittinen Ilppo Silakoski Olavi Suominen 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1093-1096
We studied the indoor penetration of ambient air malodorous sulfur compounds released by pulp mills. The indoor and outdoor concentrations were simultaneously measured with automatic SO2 analyzers. The filtering effect of three different materials connected to a gaseous filter unit was tested during six study periods. The tested materials were Sorbixofil® based on gypsum impregnated by KMnO4 Purafil® based on Al2O3, both absorbing sulfur compounds by oxidation, and carbonized tissue. The periods lasted from 14 to 88 days. The results indicated that malodorous sulfur air pollutants penetrated indoors effectively, but after some delay because the dilution was slow. In a comparison of different filter materials, Purafil® was the most effective, producing low indoor concentrations. The study concludes that people living near pulp mills are exposed to substantial amounts of malodorous air pollutants, both indoors and outdoors. This exposure can be reduced by using gaseous sulfur sensitive filter materials connected to a controlled ventilation system. 相似文献
36.
Ann-Christine Albertsson Mikael Gröning Minna Hakkarainen 《Journal of Polymers and the Environment》2006,14(1):9-13
Emission of low molar mass compounds from different polymeric materials was determined and the results from the volatile analysis
were applied to predict the degree of degradation and long-term properties, to determine degradation rates and mechanisms,
to differentiate between biotic and abiotic degradation and for quality control work. Solid-phase microextraction and solid-phase
extraction together with GC-MS were applied to identify and quantify the low molar mass compounds. Volatiles were released
and monitored at early stages of degradation before any matrix changes were observed by e.g. SEC, DSC and tensile testing.
The analysis of volatiles can thus also be applied to detect small differences between polymeric materials and their susceptibility
to degradation. The formation of certain degradation products correlated with the changes taking place in the polymer matrix,
these indicator products could, thus, be analysed to rapidly predict the degree of degradation in the polymer matrix and further
to predict the long-term properties and remaining lifetime of the product. 相似文献
37.
Miina Karjalainen Betina Kozlowsky-Suzuki Maiju Lehtiniemi Jonna Engström-Öst Harri Kankaanpää Markku Viitasalo 《Marine Biology》2006,148(4):683-691
Cyanobacterial blooms are a common phenomenon in the Baltic Sea, and the hepatotoxin nodularin has been frequently detected
in certain Baltic Sea fishes and mussels. However, there is no knowledge about the naturally occurring concentrations of nodularin
in Baltic Sea zooplankton. The aim of this study was to survey the concentrations of nodularin in natural zooplankton assemblages,
and to study the depuration of nodularin in one common copepod species, Eurytemora affinis, experimentally. The nodularin concentrations in common zooplankton species were determined from field-collected samples
from the northern Baltic Proper in 2001 and 2002, during cyanobacterial blooms, and the samples were analysed by ELISA immunoassay.
Nodularin could be detected from the field-collected zooplankton, suggesting that during a natural bloom event toxins accumulate
in their tissues. The concentrations were relatively low (0.07±0.01 μg g−1 ww), ranging from below detection limit to 0.62 μg g−1 ww. Some variation occurred in the concentrations between species and years; generally concentrations were higher in 2001
than in 2002. In the depuration experiment E. affinis copepods were fed with toxic Nodularia spumigena for 24 h, and their toxin contents were monitored for 24 h after transferring them to filtered seawater. A rapid decrease
in nodularin concentrations occurred during the first 0.5–3 h after the exposure. However, after a 24-h depuration period
in filtered seawater, nodularin could be still detected in E. affinis tissues, indicating that part of the accumulated nodularin, or its derivatives, could be transferred to planktivores. 相似文献
38.
Spatial information in ecosystem service assessment: data applicability in the cascade model context
Harri Tolvanen Mia Rönkä Petteri Vihervaara Matti Kamppinen Céline Arzel Nina Aarras 《Journal of Land Use Science》2016,11(3):350-367
Spatial information and geographical information systems (GISs) are widely used in ecosystem service research, but both the information and the methods need to be properly understood in order to make coherent analyses. We discuss the practical challenges of incorporating spatial data to ecosystem service assessment in an agricultural landscape and apply the ecosystem service cascade model to put different data into context. We review the prerequisites and practices for successful ‘ecosystem service GIS’ and provide a structured view of the information and data needed in the assessment of ecosystem services at a regional scale. Due to the heterogeneity of the spatial data, the regional characteristics should be considered in environmental decision-making through ethnographic research on local expertise to make optimal choices in using spatial information. 相似文献
39.
Sex ratios of ants have been shown to vary with food resource levels in several studies, but it is not known whether forest
clear-cutting has any effect on sex ratio of aphid-tending forest-dwelling ants. We investigated whether the offspring sex
ratio of the forest dwelling ant Formica aquilonia varied as a response to clear-cutting. We found that the proportion of males was smaller in clear-cuts than in adjacent forests.
Our results are among the first showing that anthropogenic changes in forest structures may have a potential to modify sex
ratios of social insects and other forest-dwelling animals. 相似文献