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41.
Climate change is likely to have large effects on the Baltic Sea ecosystem. Simulations indicate 2–4 °C warming and 50–80 % decrease in ice cover by 2100. Precipitation may increase ~30 % in the north, causing increased land runoff of allochthonous organic matter (AOM) and organic pollutants and decreased salinity. Coupled physical–biogeochemical models indicate that, in the south, bottom-water anoxia may spread, reducing cod recruitment and increasing sediment phosphorus release, thus promoting cyanobacterial blooms. In the north, heterotrophic bacteria will be favored by AOM, while phytoplankton production may be reduced. Extra trophic levels in the food web may increase energy losses and consequently reduce fish production. Future management of the Baltic Sea must consider the effects of climate change on the ecosystem dynamics and functions, as well as the effects of anthropogenic nutrient and pollutant load. Monitoring should have a holistic approach, encompassing both autotrophic (phytoplankton) and heterotrophic (e.g., bacterial) processes.  相似文献   
42.
Polycyclic aromatic hydrocarbons (PAH) have been determined in sewage discharge, mussels and tap water by glass capillary gas chromatography. Up to 30 PAH compounds have been identified. The concentration levels are low, respectively 0.8 – 7.7μg/1, 0.5–1.1 μg/g and 0.002 – 0.2μg/1 of sum PAH have been determined in sewage discharge, mussels and tap water. The accumulation rate in mussels seems to be rather slow at the ambient water concentrations.  相似文献   
43.
The phosphorus load originating from crop production and animal husbandry is a major contributor to the eutrophication of lakes, rivers and coastal waters. The P losses to surface waters may, however, differ drastically due to the diversity of agricultural production systems practised under contrasting environmental conditions. To assess the most problematic types of agriculture, we need information on the P load from different alternative farming practices. Such information cannot, however, be obtained solely from field runoff experiments, as the number of treatment combinations required to account for all relevant farming systems and environmental conditions far exceeds our research capabilities. To facilitate the comparison of P loads, we therefore need reasonably simple models. A key factor controlling the P load from agriculture is the past and present use of nutrients in fertilizers and manure in relation to a crop's uptake, i.e. the soil-surface balance of P. Here, we present a simple empirical model that relates the P surplus (or deficit) in a farm to the edge-of-field losses of algal-available P. Based on long-term fertilizer trials, the model first estimates the change in soil-test P of top soil with the aid of the soil-surface balance of P. Soil-test P is then used to approximate the concentration of dissolved reactive P in surface runoff and drainage flow, as adjusted for different P application types. The loss of particulate P is obtained from typical erosion rates. The model can be applied in life-cycle analyses and in assessing future developments. We illustrate use of the model by calculating the loss of algal-available P from conventional and organic crop and dairy farms located on clay and fine sand soils.  相似文献   
44.
A total of 800 patients were randomized at the 9th to 11th week of pregnancy either for transcervical chorionic villus sampling (CVS) on the day of trial entry or for amniocentesis (AC) at the 16th week. The indication for fetal karyotyping was maternal age in 94 per cent of the cases; the mean maternal age was 39.2 years. An adequate sample was obtained in 98.3 per cent of the cases in the CVS group and in all cases in the AC group. Retesting was indicated in 3.3 per cent of the CVS cases. An abnormal karyotype was found in 6.1 per cent of the CV samples and in 4.5 per cent of the amniotic fluid samples. There was one false-positive chromosome result in both groups. Twelve (3.1 per cent) miscarriages occurred by the 22nd week of pregnancy in the CVS group in pregnancies intended to continue. No difference was seen between the groups for total fetal loss rates. The number of surviving infants in the CVS group was 92.2 per cent and in the AC group 91.7 per cent (rate difference 0.5 per cent (95 per cent confidence interval − 3.3 to 4.3)). In our study, both the diagnostic accuracy and the risk of fetal loss were equal in the CVS and AC groups.  相似文献   
45.
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   
46.
Pikes were sampled in May 1980 from three areas of the Lake Päijänne, Finland and analyzed for their contents of total mercury, methyl mercury, hexachlorobenzene (HCB), DDE, PCB and chlorophenolic residues. An improved method for methyl mercury determination was applied and 82–84 % methylation of mercury in pikes regardless of area or biological variation was observed. Statistical analysis with previous results from the same areas gave a very significant decreasing trend of mercury levels at all three areas from 1970 to 1980. Future levels of mercury in fish to be consumed as food could be estimated from the trend regression. The very low levels of DDE and PCB showed some increasing trend when the influence of fat contents was eliminated by covariance analysis. General appearance of HCB at sub-ppb level was observed. Also pentachlorophenol occured at 10–70 ppb (fresh weight) levels at all areas, but the other chlorophenols were abundant only at Tiirinselkä which is most contaminated by pulp bleaching effluents.  相似文献   
47.
The need to develop biological effects monitoring to facilitate a reliable assessment of hazardous substances has been emphasized in the Baltic Sea Action Plan of the Helsinki Commission. An integrated chemical–biological approach is vitally important for the understanding and proper assessment of anthropogenic pressures and their effects on the Baltic Sea. Such an approach is also necessary for prudent management aiming at safeguarding the sustainable use of ecosystem goods and Services. The BEAST project (Biological Effects of Anthropogenic Chemical Stress: Tools for the Assessment of Ecosystem Health) set out to address this topic within the BONUS Programme. BEAST generated a large amount of quality-assured data on several biological effects parameters (biomarkers) in various marine species in different sub-regions of the Baltic Sea. New indicators (biological response measurement methods) and management tools (integrated indices) with regard to the integrated monitoring approach were suggested.  相似文献   
48.
Many conservation actions are justified on the basis of managing biodiversity. Biodiversity, in terms of species richness, is largely the product of rare species. This is problematic because the intensity of sampling needed to characterize communities and patterns of rarity or to justify the use of surrogates has biased sampling in favor of space over time. However, environmental fluctuations interacting with community dynamics lead to temporal variations in where and when species occur, potentially affecting conservation planning by generating uncertainty about results of species distribution modeling (including range determinations), selection of surrogates for biodiversity, and the proportion of biodiversity composed of rare species. To have confidence in the evidence base for conservation actions, one must consider whether temporal replication is necessary to produce broad inferences. Using approximately 20 years of macrofaunal data from tidal flats in 2 harbors, we explored variation in the identity of rare, common, restricted range, and widespread species over time and space. Over time, rare taxa were more likely to increase in abundance or occurrence than to remain rare or disappear and to exhibit temporal patterns in their occurrence. Space–time congruency in ranges (i.e., spatially widespread taxa were also temporally widespread) was observed only where samples were collected across an environmental gradient. Fifteen percent of the taxa in both harbors changed over time from having spatially restricted ranges to having widespread ranges. Our findings suggest that rare species can provide stability against environmental change, because the majority of species were not random transients, but that selection of biodiversity surrogates requires temporal validation. Rarity needs to be considered both spatially and temporally, as species that occur randomly over time are likely to play a different role in ecosystem functioning than those exhibiting temporal structure (e.g., seasonality). Moreover, temporal structure offers the opportunity to place management and conservation activities within windows of maximum opportunity.  相似文献   
49.

Problem

This study examined novice drivers’ overconfidence by comparing their self-assessed driver competence with the assessments made by driving examiners.

Method

A Finnish (n = 2,739) and a Dutch sample (n = 239) of drivers license candidates assessed their driver competence in six areas and took the driving test.

Result and Discussion

In contrast to previous studies where drivers have assessed their skill in comparison to the average driver, a smaller proportion overestimated and a larger proportion made realistic self-assessments of their driver competence in the present study, where self-assessments were compared with examiner assessments. Between 40% and 50% of the candidates in both samples made realistic assessments and 30% to 40% overestimated their competence. The proportion of overestimation was greater in the Dutch than in the Finnish sample, which might be explained by greater possibilities for practicing self-assessment in the Finnish driver education system. Similar to other self-assessment studies that indicate that incompetence is related to overestimation, a larger proportion of candidates that failed the test overestimated their skill compared to those who passed. In contrast to other studies, males did not overestimate their skills more than females, and younger driver candidates were not more overconfident than older drivers.

Impact on traffic safety

Although a great proportion of the candidates made a realistic assessment of their own driver competence, overestimation is still a problem that needs to be dealt with. To improve the accuracy of novice drivers’ self-assessment, methods for self-assessment training should be developed and implemented in the driver licensing process.  相似文献   
50.
ABSTRACT

The failure of societies to respond in a concerted, meaningful way to climate change is a core concern of the social science climate literature. Existing explanations of social inertia display little coherence. Here, a theoretical approach is suggested that integrates disparate perspectives on social inertia regarding climate change. Climate change constitutes a potential cultural trauma. The threat of cultural trauma is met with resistance and attempts to restore and maintain the status quo. Thus, efforts to avoid large-scale social changes associated with climate change constitute an effort to avoid cultural trauma, and result in social inertia regarding climate change at individual, institutional, and societal levels. Existing approaches to social inertia are reviewed. An intellectual framework utilizing the work of Pierre Bourdieu is proposed to integrate these different levels of social interaction. Social processes that maintain social order and thus avoid cultural trauma create social inertia regarding climate change.  相似文献   
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