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排序方式: 共有103条查询结果,搜索用时 31 毫秒
71.
Bathymetry, the underwater topography, is a fundamental property of oceans, seas, and lakes. As such it is important for a wide range of applications, like physical oceanography, marine geology, geophysics and biology or the administration of marine resources. The exact requirements users may have regarding bathymetric data are, however, unclear. Here, the results of a questionnaire survey and a literature review are presented, concerning the use of Baltic Sea bathymetric data in research and for societal needs. It is demonstrated that there is a great need for detailed bathymetric data. Despite the abundance of high-quality bathymetric data that are produced for safety of navigation purposes, the digital bathymetric models publicly available to date cannot satisfy this need. Our study shows that DBMs based on data collected for safety of navigation could substantially improve the base data for administrative decision making as well as the possibilities for marine research in the Baltic Sea.  相似文献   
72.
The aim of the work was to estimate plutonium inflow from the Vistula River’s catchments area to the Baltic Sea. There were differences in plutonium activities depending on season and sampling site. The highest activities of 238Pu and 239+240Pu were transported from the Vistula River watershed to the Baltic Sea in spring and the lowest in summer. Annually, the southern Baltic Sea is enriched via the Vistula River with 10.3 MBq of 238Pu and 89.0 MBq of 239+240Pu. The enhanced concentration of plutonium in water from the Vistula River is the result of its runoff from the Vistula drainage area, mostly from snowmelt, enhanced rainfalls and leached materials from river bed.  相似文献   
73.
This seven-year survey was primarily targeted to quantification of production of nodularin-R (NOD-R), a cyclic pentapeptide hepatotoxin, in Baltic Sea cyanobacteria waterblooms. Additionally, NOD-R and microcystin-LR (MC-LR; a cyclic heptapeptide toxin) sedimentation rates and NOD-R sediment storage were estimated. NOD-R production (70-2450 μg m−3; ∼1 kg km−2 per season) and sedimentation rates (particles; 0.03-5.7 μg m−2 d−1; ∼0.3 kg km−2 per season) were highly variable over space and time. Cell numbers of Nodularia spumigena did not correlate with NOD-R quantities. Dissolved NOD-R comprised 57-100% of total NOD-R in the predominantly senescent, low-intensity phytoplankton blooms and seston. Unprecedentedly intensive MC-LR sedimentation (0.56 μg m−2 d−1) occurred in 2004. Hepatotoxin sedimentation rates highly exceeded those of anthropogenic xenobiotics. NOD-R storage in surficial sediments was 0.4-20 μg kg−1 (∼0.1 kg km−2). Loss of NOD-R within the chain consisting of phytoplankton, seston and soft sediments seemed very effective.  相似文献   
74.
The importance of riparian vegetation to support stream function and provide riparian bird habitat in semiarid landscapes suggests that standardized assessment tools that include vegetation criteria to evaluate stream health could also be used to assess habitat conditions for riparian-dependent birds. We first evaluated the ability of two visual assessments of woody vegetation in the riparian zone (corridor width and height) to describe variation in the obligate riparian bird ensemble along 19 streams in eastern Oregon. Overall species richness and the abundances of three species all correlated significantly with both, but width was more important than height. We then examined the utility of the riparian zone criteria in three standardized and commonly used rapid visual riparian assessment protocols—the USDI BLM Proper Functioning Condition (PFC) assessment, the USDA NRCS Stream Visual Assessment Protocol (SVAP), and the U.S. EPA Habitat Assessment Field Data Sheet (HAFDS)—to assess potential riparian bird habitat. Based on the degree of correlation of bird species richness with assessment ratings, we found that PFC does not assess obligate riparian bird habitat condition, SVAP provides a coarse estimate, and HAFDS provides the best assessment. We recommend quantitative measures of woody vegetation for all assessments and that all protocols incorporate woody vegetation height. Given that rapid assessments may be the only source of information for thousands of kilometers of streams in the western United States, incorporating simple vegetation measurements is a critical step in evaluating the status of riparian bird habitat and provides a tool for tracking changes in vegetation condition resulting from management decisions.  相似文献   
75.
The synthesis of the BONUS+ research is introduced. The HELCOM Baltic Sea Action Plan is examined as a case to illustrate the potentials and challenges in building the science–policymaking interface on a macroregional level. The projects address environmental challenges in the Baltic Sea as defined by the Baltic Sea Action Plan, or consider the environmental governance and decision making within the Baltic Sea context in general. Eutrophication, biodiversity, hazardous substances, maritime activities, and the environment governance are addressed, as are crosscutting issues, such as the impact of climate change, maritime spatial planning and impacts of future development on ecosystem services. The projects contributed to relevant policy developments: 37 consultations carried out at EU level, 49 modifications to policy documents and action plans, 153 suggestions for the efficacy of pertinent public policies and governance, and in 570 occasions, scientists working in BONUS+ projects served as members or observers in scientific and stakeholder committees.  相似文献   
76.
The ever increasing impact of the marine industry and transport on vulnerable sea areas puts the marine environment under exceptional pressure and calls for inspired methods for mitigating the impact of the related risks. We describe a method for preventive reduction of remote environmental risks caused by the shipping and maritime industry that are transported by surface currents and wind impact to the coasts. This method is based on characterizing systematically the damaging potential of the offshore areas in terms of potential transport to vulnerable regions of an oil spill or other pollution that has occurred in a particular area. The resulting maps of probabilities of pollution to be transported to the nearshore and the time it takes for the pollution to reach the nearshore are used to design environmentally optimized fairways for the Gulf of Finland, Baltic Proper, and south-western Baltic Sea.  相似文献   
77.
Carl Rolff  Tina Elfwing 《Ambio》2015,44(7):601-611
The study showed that the open water of the Bothnian Sea (BS) is likely to have shifted from altering nitrogen and phosphorous limitations of the spring bloom to more nitrogen-limited conditions during the last 20 years. This is affected by the by inflow of phosphate-rich and oxygen-depleted water from depths near the halocline in the northern Baltic Proper, where severe oxygen conditions currently cause extreme phosphate concentrations in the deep water. The change in relation between inorganic nitrogen and phosphorous in the BS occurs first in the deep water and then progresses to the surface water. The change can potentially cause increased production in the BS and more frequent cyanobacterial blooms. There does not appear to be any immediate concern in the short-term perspective for the state of the BS, but a progression of the processes may lead to a more eutrophic state of the BS.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-015-0675-3) contains supplementary material, which is available to authorized users.  相似文献   
78.
Coastal dunes around the Baltic Sea have received small amounts of atmospheric nitrogen and are rather pristine ecosystems in this respect. In 19 investigated dune sites the atmospheric wet nitrogen deposition is 3-8 kg N ha−1 yr−1. The nitrogen content of Cladonia portentosa appeared to be a suitable biomonitor of these low to medium deposition levels. Comparison with EMEP-deposition data showed that Cladonia reflects the deposition history of the last 3-6 years. With increasing nitrogen load, we observed a shift from lichen-rich short grass vegetation towards species-poor vegetation dominated by the tall graminoid Carex arenaria. Plant species richness per field site, however, does not decrease directly with these low to medium N deposition loads, but with change in vegetation composition. Critical loads for acidic, dry coastal dunes might be lower than previously thought, in the range of 4-6 kg N ha−1 yr−1 wet deposition.  相似文献   
79.
Hassler B 《Ambio》2011,40(2):170-178
Marine governance of oil transportation is complex. Due to difficulties in effectively monitoring procedures on vessels en voyage, incentives to save costs by not following established regulations on issues such as cleaning of tanks, crew size, and safe navigation may be substantial. The issue of problem structure is placed in focus, that is, to what degree the specific characteristics and complexity of intentional versus accidental oil spill risks affect institutional responses. It is shown that whereas the risk of accidental oil spills primarily has been met by technical requirements on the vessels in combination with Port State control, attempts have been made to curb intentional pollution by for example increased surveillance and smart governance mechanisms such as the No-Special-Fee system. It is suggested that environmental safety could be improved by increased use of smart governance mechanisms tightly adapted to key actors’ incentives to alter behavior in preferable directions.  相似文献   
80.
The aim of the paper was plutonium (238Pu and 239+240Pu) determination in seabirds, permanently or temporarily living in northern Poland at the Baltic Sea coast. Together 11 marine birds species were examined: 3 species permanently residing in the southern Baltic, 4 species of wintering birds and 3 species of migrating birds. The obtained results indicated plutonium is non-uniformly distributed in organs and tissues of analyzed seabirds. The highest plutonium content was found in the digestion organs and feathers, the smallest in skin and muscles. The plutonium concentration was lower in analyzed species which feed on fish and much higher in herbivorous species. The main source of plutonium in analyzed marine birds was global atmospheric fallout.  相似文献   
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