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1.
The governments around the Baltic Sea have agreed on a new set of targets for nutrient load reductions. The major motive for this is new and better knowledge about the link between nutrient loads and water transparency in different parts of the sea. The Baltic Sea Action Plan (BSAP) defines target for transparency in different marine basins, the load reductions necessary to meet transparency targets and a scheme for the distribution of the abatement burden between countries adjacent to the sea.  相似文献   

2.
近海生态系统的人为营养盐输入及其控制对策浅析   总被引：1，自引：1，他引：0  
人为活动每年新增大量的活性氮、磷,导致全球氮、磷循环失衡,新增活性氮、磷主要来源于合成氮肥的生产和施用、畜肥的施用、具固氮能力的农作物如豆科植物等的大规模种植,以及化石燃料燃烧产生的氮氧化物等,而农作物生产与畜禽养殖是改变全球氮、磷循环的主要原因。随着生活污水排放量和化肥施用量的激增,大量氮、磷进入近海,导致营养盐污染和富营养化,这已成为全球性的海洋生态环境问题,通过河流径流和大气沉降进入近海生态环境中的新增氮和磷一半以上与人为活动有关。本文以波罗的海和东海为例,分析了发达国家和发展中国家近海的富营养化问题,研究表明从源头缓解富营养化的对策应同时聚焦氮与磷负荷的削减,具体措施包括降低农业生产活动中化肥的土壤渗漏、合理施肥、种植多年生植物和种植休耕季覆被作物等。  相似文献   

3.
Anthropogenic eutrophication affects the Mediterranean, Black, North and Baltic Seas to various extents. Responses to nutrient loading and methods of monitoring relevant indicators vary regionally, hindering interpretation of ecosystem state changes and preventing a straightforward pan-European assessment of eutrophication symptoms. Here we summarize responses to nutrient enrichment in Europe's seas, comparing existing time-series of selected pelagic (phytoplankton biomass and community composition, turbidity, N:P ratio) and benthic (macro flora and faunal communities, bottom oxygen condition) indicators based on their effectiveness in assessing eutrophication effects. Our results suggest that the Black Sea and Northern Adriatic appear to be recovering from eutrophication due to economic reorganization in the Black Sea catchment and nutrient abatement measures in the case of the Northern Adriatic. The Baltic is most strongly impacted by eutrophication due to its limited exchange and the prevalence of nutrient recycling. Eutrophication in the North Sea is primarily a coastal problem, but may be exacerbated by climatic changes. Indicator interpretation is strongly dependent on sea-specific knowledge of ecosystem characteristics, and no single indicator can be employed to adequately compare eutrophication state between European seas. Communicating eutrophication-related information to policy-makers could be facilitated through the use of consistent indicator selection and monitoring methodologies across European seas. This work is discussed in the context of the European Commission's recently published Marine Strategy Directive.  相似文献   

4.
The St. Petersburg Baltic eutrophication model (SPBEM) is used to assess the ecological condition of the sea under possible changes in climate and nutrient loads in the 21st century. According to model estimates, in the future climate water quality will worsen, compared to modern conditions. This deterioration is stronger in the climate warming scenario with a stronger change in future near-surface air temperature. In the considered scenarios of climate change, climate warming will lead to an increase in the area of anoxic and hypoxic zones. Reduction of nutrient loading, estimated in accordance with the Baltic Sea Action Plan, will only be able to partially compensate for the negative effects of global warming.  相似文献   

5.
Pore Water Nutrient Regeneration in Shallow Coastal Bohai Sea, China   总被引：1，自引：0，他引：1  
The regeneration of pore water nutrients was studied and the contribution of benthic nutrient fluxes to the overlying water was evaluated on the basis of field specific observations conducted in September–October 1998 and April–May 1999 in the Bohai Sea. Nutrient concentrations in sediment pore waters were examined by incubating sediment core samples with overlying seawater in air and/or nitrogen conditions. Nutrient diffusion fluxes calculated by diagenetic equations were within a factor of 2 during incubations. The factors affecting nutrient diffusion across sediment/water interface include bioturbation, nitrification, denitrification, adsorption, and dissolution. The regeneration of nutrients from sediments will increase nutrient loads of the Bohai Sea and affect nutrient atomic ratios in this region. Among nutrient sources from riverine input, atmospheric deposition and sediment regeneration, ammonium and phosphate mainly came from atmospheric deposition (>50%); nitrate was mainly transported by riverine input into the Sea, silicate from sediment regeneration accounts up to 60%. This demonstrates that nutrient regeneration in sediments contributes more silicate than riverine input and atmospheric deposition together, but benthic flux contributes very much less phosphate and nitrate relative to riverine input and atmospheric deposition. The benthic fluxes of nutrients may lead to a decrease of the amount of nitrate, an increase of phosphate, ammonia and silicate in the water column. The release of silicate from sediments may compensate the decrease of silicate due to the reduction of riverine discharge. Nutrient regeneration in sediment may have an important influence on the eutrophic character of coastal waters in this region. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

6.
A full re-calculation of Water Framework Directive reference and target concentrations for German coastal waters and the western Baltic Sea is presented, which includes a harmonization with HELCOM Baltic Sea Action Plan (BSAP) targets. Further, maximum allowable nutrient inputs (MAI) and target concentrations in rivers for the German Baltic catchments are suggested. For this purpose a spatially coupled, large scale and integrative modeling approach is used, which links the river basin flux model MONERIS to ERGOM-MOM, a three-dimensional ecosystem model of the Baltic Sea. The years around 1880 are considered as reference conditions reflecting a high ecological status and are reconstructed and simulated with the model system. Alternative approaches are briefly described, as well. For every WFD water body and the open sea, target concentrations for nitrogen and phosphorus compounds as well as chlorophyll a are provided by adding 50% to the reference concentrations. In general, the targets are less strict for coastal waters and slightly stricter for the sea (e.g. 1.2 mg/m³ chl.a summer average for the Bay of Mecklenburg), compared to current values. By taking into account the specifics of every water body, this approach overcomes the inconsistencies of earlier approaches. Our targets are well in agreement with the BSAP targets, but provide spatially refined and extended results. The full data are presented in Appendix A1 and A2.To reach the targets, German nitrogen inputs have to be reduced by 34%. Likely average maximum allowable concentrations in German Baltic rivers are between 2.6 and 3.1 mg N/l. However, the concrete value depends on the scenario and uncertainties with respect to atmospheric deposition. To our results, MAI according to the BSAP may be sufficient for the open sea, but are not sufficient to reach a good WFD status in German coastal waters.  相似文献   

7.
Estuaries are often seen as important filters between land and the sea for inorganic and organic nutrients. This paper aims at estimating the estuarine fluxes of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and dissolved silicate for the major oligothrophic and pristine rivers running into the Bothnian Bay (BB) and the Bothnian Sea (BS), the northern subarctic subbasins of the Baltic Sea. Long-term data sets for these rivers and their estuaries as well as for the BB and BS were analyzed to assess whether these estuaries are sinks for inorganic nutrients. Most studied estuaries can be characterized as salt wedge estuaries with little exchange between the fresh seaward-flowing river water and the inward-flowing seawater. Estimates of water transit times ranged between 1 and 14 days. In most estuaries of the BB, N-depleted river water meets P-depleted seawater during the growth period. These findings were corroborated by mixing diagrams showing that the inner areas of the estuaries were N-depleted in summer. In the BS, on the other hand, both rivers and seawater were mostly N-depleted during summer. Thus, for most estuaries of this region of the Baltic Sea, primary productivity is presumably lower than or equal to that of offshore. The low productivity is also reflected in the sediments. The coastal sediments did not differ from the offshore stations in accumulation rates as well as the content of organic matter and nutrients, indicating that estuarine nutrient burial is not always higher as normally observed in other temperate systems. Finally, the estuaries of the pristine rivers in the northernmost part of the BB import DIN during summer, whereas the estuaries of the rivers in the BS import DIP during winter, from the sea.  相似文献   

8.
Historic changes in flux of matter and nutrient budgets in the Bohai Sea   总被引：1，自引：0，他引：1  
Over the past four periods （ 1959--1960, 1982--1983, 1992--1993, and 1998--1999）, the ecosystem of the Bohai Sea changed due to both a significant decrease of river water discharge from the Huanghe River and a reduction of precipitation. The shifts in nutrient chemistry could result in changes in the phytoplankton composition with an increased potential for non-diatom algal blooms. Simple box model was used to estimate the water - mass balance and nutrient budgets for the Bohai Sea. Water budgets indicate that the residual flow changed from out of the Bohai Sea before 1993, but became inflow to the Bohai Sea after then. The nutrient budgets developed indicate that the Bohai Sea was a sink for nutrients except for phosphate in 1959--1960 and 1982-- 1983 and for silicate in 1982--1983. Net water flow transports nutrients out of the Bohai Sea in 1959--1960, 1982--1983 and 1992--1993, but into the sea in 1998--1999 due to climate changes, such as precipitation and subsequent freshwater discharge. The residual fluxes of nutrients are minor relative to atmospheric deposition and riverine inputs. Conversions of phosphate values to carbon by stoichiometric ratios were used to predict that the system was net heterotrophic before 1982--1983 and net autotrophic after then. Nutrient budgets can explain the change of nutrient concentrations in the Bohai Sea except nitrates, which should include the surface runoff.  相似文献   

9.
Massive blooms of Phaeocystis colonies usually occur in the Belgian coastal zone (BCZ) between spring and summer diatom blooms but their relative magnitude varies between years. In order to understand this interannual variability, we used the biogeochemical MIRO model to explore the link between diatom and Phaeocystis blooms and changing nutrient loads and meteorological conditions over the last decade. For this application, MIRO was implemented in a simplified 3-box representation of the domain between the Baie de Seine and the BCZ. MIRO was run over the 1989–2003 period using actual photosynthetic active radiation (PAR), seawater temperature and riverine nutrient loads as forcing. The water mass residence time was calculated for each box based on a monthly water budget estimated from 1993–2003 water flow simulations of the three-dimensional hydrodynamical model COHSNS-3D. Overall MIRO simulations compare fairly well with nutrient and phytoplankton data collected in the central BCZ but indicate the importance of the hydrodynamical resolution frame for correctly describing the extremely high nutrient concentrations and biomass observed in the BCZ. Analysis of model results suggests that while interannual variability in diatom biomass depends on both meteorological conditions (light and temperature) and nutrient loads, Phaeocystis blooms are mainly controlled by nutrients. Further sensitivity tests with varying N and P loads suggest that only N reduction will result in significantly decreased Phaeocystis blooms without negative affects on diatoms, while P reduction will negatively affect diatoms. Moreover, Atlantic nutrient loads play such a great role in BCZ enrichment that reduction of Scheldt nutrient loads only is not sufficient to significantly decrease phytoplankton blooms in the BCZ. It is concluded that future nutrient reduction policies aimed to decrease Phaeocystis blooms in the BCZ without impacting diatoms should target the decrease of N loads in both the Seine and the Scheldt rivers.  相似文献   

10.
Rivers are important sources of freshwater and nutrients for the Mediterranean and Black Sea. We present a reconstruction of the spatial and temporal variability of these inputs since the early 1960s, based on a review of available data on water discharge, nutrient concentrations and climatic parameters. Our compilation indicates that Mediterranean rivers suffer from a significant reduction in freshwater discharge, contrary to rivers of the Black Sea, which do not have clear discharge trends. We estimate this reduction to be at least about 20% between 1960 and 2000. It mainly reflects recent climate change, and dam construction may have reduced discharge even further. A similar decrease can also be expected for the fluxes of dissolved silica (Si), strongly controlled by water discharge and potentially reduced by river damming as well. This contrasts with the fluxes of nitrogen (N) and phosphorus (P) in Mediterranean and Black Sea rivers, which were strongly enhanced by anthropogenic sources. Their total inputs to the Mediterranean Sea could have increased by a factor of >5. While N still remained at elevated levels in 2000, P only increased up to the 1980–1990s, and then rapidly dropped down to about the initial values of the 1960s. With respect to the marine primary production that can be supported by the riverine nutrient inputs, Mediterranean and the Black Sea rivers were mostly phosphorus limited during the study period. Their anthropogenic nutrient enrichment could only have had a fertilizing effect before the general decline of the P loads. When also considering Si as a limiting element, which is the case for siliceous primary producers such as diatoms, silica limitation may have become a widespread phenomenon in the Mediterranean rivers since the early 1980s. For the Black Sea rivers, this already started the late 1960s. Gross primary production sustained by rivers (PPR) represents only less than 2% of the gross production (PP) in the Mediterranean, and less than 5% in the Black Sea. Possible ecological impacts of the changing river inputs should therefore be visible only in productive coastal areas, such as the Gulf of Lions, where PPR can reach more than two thirds of PP. Reported ecosystem changes both in the Adriatic Sea and the Black Sea are concomitant with major changes in the reconstructed river inputs. Further work combining modelling and data collection is needed to test whether this may also have been the case for coastal ecosystems at other places in the Mediterranean and Black Sea.  相似文献   

11.
Abstract. The nutrient cycling of Epidavros, a deep basin in the Saronikos Gulf, was studied in relation to various environmental factors during 1973–1976 at a station characterized by stagnant conditions. The regeneration of nutrients was related to the consumption of oxygen, and a seasonal nutrient cycle occurred with low nutrient concentrations in the spring and summer, followed by high nutrient levels in autumn and winter. In addition high values of nitrate and silicate were observed in the deeper waters, which tended to be anoxic, although the water masses were renewed during spring 1974. The distribution pattern of nutrients together with nutrient ratios were compared with previous studies of the same and neighbouring areas as well as of other isolated basins. A stoichiometric model indicates that plankton organisms in the Epidavros basin have approximate atomic ratios for C: N: P of 150: 14:1, while the ratio of change for nitrogen and phosphorus in the water is only 8.8:1 by atoms. This is probably because of the slow rate of regeneration of nitrogenous material and/or assimilation and regeneration in organic forms. The water/plankton relation in the Epidavros basin appears to be very similar to that in the Baltic Sea.  相似文献   

12.
The Paleozoic rocks of Kaliningrad oblast and the adjacent areas of the SE Baltic Sea have recently became exploration targets. The small size and number of prospective structures, as well as the small size of the oil reserves in the onshore areas, have resulted in a decline in production and a decrease in exploration activity. At the same time, previous studies conducted by the Institute of Oceanology of the Russian Academy of Sciences and other institutions show that the SE Baltic Sea contains numerous yet-to-be-explored structures, which could be attractive exploration targets. Recent studies indicate that the region was intensely intruded by numerous diabase sills, which cut across Paleozoic reservoir rocks. This fact may have both positive and negative implications for the petroleum potential of the basin and should be taken into account in outlining the possible future directions for resource exploration. This study presents data on the distribution, sizes, ages, composition, and volumes of the mafic intrusions and discusses their thermal effects on the petroleum potential of the SE Baltic Basin.  相似文献   

13.
The ecosystem model ERSEM II has been used to hindcast the development of the ecosystem of the North Sea during the years 1955 to 1993. The simulation was driven by the box-aggregated output from a general circulation model of the North Sea of corresponding duration; radiation, river inputs, atmospheric input and boundary conditions at the borders to the Atlantic Ocean and to the Baltic Sea were applied as realistically as possible. The general features of the eutrophication process are reproduced in the hindcast: the coastal areas show strong changes in nutrient concentrations in the hindcast as well as in the observations. Eutrophication not only shows up in the nutrient concentrations, but also in primary production. The simulated spatial distributions of phosphate, nitrate and primary production compare well with the observed ones. In addition, the hindcast simulates considerable trend-like changes of the nutrients in the southern part of the North Sea, where the nutrients are transported from the continental coastal strip to the southern central North Sea. The line from the river Humber to southern Norway separates the region of noticeable anthropogenic influence of riverine and atmospheric input from the northern area, which is mainly influenced by the Atlantic nutrient inflow. The observed annual cycles in the central and northern North Sea are quite well reproduced by the hindcast. The comparison of the hindcast with the long-term observations at two sites in the continental coastal zone of the North Sea shows that the long-term behaviour of phosphate, nitrate and silicate is simulated well. Primary production is increased in summers during the main period of eutrophication, 1975 to 1989, in the hindcast and in the observations. The flagellates at Helgoland, however, experience much more pronounced annual cycles with much less interannual variability in the hindcast than in the observations.  相似文献   

14.
Primary production, nutrient concentrations, phytoplankton biomass (incl. chlorophyll a) and water transparency (Secchi depth), are important indicators of eutrophication. Earlier basin-wide primary production estimates for the Baltic Sea, a shallow shelf sea, were based mainly on open-sea data, neglecting the fundamentally different conditions in the large river plumes, which might have substantially higher production. Mean values of the period 1993–1997 of nutrient concentrations (phosphate, nitrate, ammonium and silicate), phytoplankton biomass, chlorophyll a (chl a) concentration, turbidity and primary production were calculated in the plumes of the rivers Oder, Vistula and Daugava and Klaipeda Strait as well as the open waters of the Arkona Sea, Bornholm Sea, eastern Gotland Sea and the Gulf of Riga. In the plumes, these values, except for primary production, were significantly higher than in the open waters. N:P ratios in the plumes were >16 (with some exceptions in summer and autumn), indicating potential P-limitation of phytoplankton growth, whereas they were <16 in the open Baltic Proper, indicating potential N-limitation. On the basis of in situ phytoplankton primary production, phytoplankton biomass and nutrient concentrations, the large river plumes and the Gulf of Riga could be characterized as eutrophic and the outer parts of the coastal waters and the open sea as mesotrophic. Using salinity to define the border of the plumes, their mean extension was calculated by means of a circulation model. Taking into account the contribution of coastal waters, the primary production in the Baltic Proper and the Gulf of Riga was 42·6 and 4·3×106 t C yr−1, respectively. Hence, an annual phytoplankton primary production in the whole Baltic Sea was estimated at 62×106 t C yr−1. The separate consideration of the plumes had only a minor effect on the estimation of total primary production in comparison with an estimate based on open sea data only. There is evidence for a doubling of primary production in the last two decades. Moreover, a replacement of diatoms by dinoflagellates during the spring bloom was noticed in the open sea but not in the coastal waters. A scheme for trophic classification of the Baltic Sea, based on phytoplankton primary production and biomass, chl a and nutrient concentrations, is proposed.  相似文献   

15.
Shelf seas such as the North Sea and the Baltic Sea are characterised by spatially and temporally varying stratification that is highly relevant for their physical dynamics and the evolution of their ecosystems. Stratification may vary from unstably stratified (e.g., due to convective surface cooling) to strongly stratified with density jumps of up to 10 kg/m3 per m (e.g., in overflows into the Baltic Sea). Stratification has a direct impact on vertical turbulent transports (e.g., of nutrients) and influences the entrainment rate of ambient water into dense bottom currents which in turn determine the stratification of and oxygen supply to, e.g., the central Baltic Sea. Moreover, the suppression of the vertical diffusivity at the summer thermocline is one of the limiting factors for the vertical exchange of nutrients in the North Sea. Due to limitations of computational resources and since the locations of such density jumps (either by salinity or temperature) are predicted by the model simulation itself, predefined vertical coordinates cannot always reliably resolve these features. Thus, all shelf sea models with a predefined vertical coordinate distribution are inherently subject to under-resolution of the density structure.To solve this problem, Burchard and Beckers (2004) and Hofmeister et al. (2010) developed the concept of vertically adaptive coordinates for ocean models, where zooming of vertical coordinates at locations of strong stratification (and shear) is imposed. This is achieved by solving a diffusion equation for the position of the coordinates (with the diffusivity being proportional to the stratification or shear frequencies). We will show for a coupled model system of the North Sea and the Baltic Sea (resolution ∼ 1.8 km) how numerical mixing is substantially reduced and model results become significantly more realistic when vertically adaptive coordinates are applied. We additionally demonstrate that vertically adaptive coordinates perform well in simulating the two dynamically different regions North Sea and Baltic Sea with a single parameter set.An analysis of the computational overhead of the adaptive coordinates indicates an increase of 5–8% in runtime. This is still less expensive than adding more sigma-layers to reduce spurious numerical mixing.  相似文献   

16.
The Baltic Sea Level Project is an international scientific observation program to unify the vertical datums of the countries of the Baltic Sea with GPS measurements. In total, 35 tide gauges on shores and islands of the Baltic were occupied with GPS in 1993. After computing a new gravimetric geoid over the Baltic Sea, it was possible to unify the datums as well as to calculate the orthometric heights and the sea surface topography values for the tide gauge stations. The results obtained are shown.  相似文献   

17.
The cod stocks in the Baltic Sea are important not only for fisheries but for the entire ecosystem utilized by numerous stakeholders around the coast. All such activities have economic values. In this note the economics of the Swedish Baltic Sea cod fishery is estimated in relation to the sector's interaction with other users of the Baltic Sea ecosystem. The results show a negative resource rent for the fishery, € −5 million without public expenses (subsidies and administrative costs), and € −13 million including public expenses. The interactions between the fisheries and tourism, seal population, carbon dioxide emissions, recreational fishing, and discards are discussed, and when monetary estimates are available these are related to the estimated resource rent.  相似文献   

18.
Regular surveys of coastal zone seabed deliver important information about geomorphologic processes such as silting of waterways. The recent introduction of the Sentinel series of sensors has allowed for the use of satellite sensing for shallow bathymetry morphology monitoring. In this context, this article presents a dedicated Geographic Information System for Baltic Sea shallow water depth monitoring on the basis of Sentinel-2 imagery. The system employs Geovisual Analytics for differential analysis of bathymetry changes as well as monitoring the visibility of known wrecks in the coastal waters of Southern Baltic Sea. Results are verified with regard to known changes in shallow water bathymetry between 28 June 2015 and 3 March 2017.  相似文献   

19.
Chromophoric dissolved organic matter (CDOM) is the major light absorber in the Baltic Sea. In this study, excitation emission matrix (EEM) fluorescence spectra and UV–visible absorption spectra of CDOM are reported as a function of salinity. Samples from different locations and over different seasons were collected during four cruises in 2002 and 2003 in the Baltic Sea in both Pomeranian Bay and the Gulf of Gdansk. Absorption by CDOM decreased with increased distance from the riverine source and reached a relatively stable absorption background in the open sea. Regression analysis showed that fluorescence intensity was linearly related to absorption by CDOM at 375 nm and aCDOM(375) absorption coefficients were inversely related to salinity. Analysis of CDOM-EEM spectra indicated that a change in composition of CDOM occurred along the salinity gradient in the Baltic Sea. Analysis of percent contribution of respective fluorophore groups to the total intensity of EEM spectra indicated that the fluorescence peaks associated with terrestrial humic components of the CDOM and total integrated fluorescence decreased with decreasing CDOM absorption. In contrast, the protein-like fraction of CDOM decreased to a lesser degree than the others. Analysis of the percent contribution of fluorescence peak intensities to the total fluorescence along the salinity gradient showed that the contribution of protein-like fluorophores increased from 2.6% to 5.1% in the high-salinity region of the transect. Fluorescence and absorption changes observed in the Baltic Sea were similar to those observed in similar transects that have been sampled elsewhere, e.g. in European estuaries, Gulf of Mexico, Mid-Atlantic Bight and the Cape Fear River plume in the South Atlantic Bight, although the changes in the Baltic Sea occurred over a much smaller salinity gradient.  相似文献   

20.
The sensitivity of the Baltic Sea mean salinity to climatic changes of the freshwater supply is analyzed. The average salinity of the Baltic Sea is about 6‰. The low salinity is an effect of a large net freshwater supply and narrow and shallow connections with the North Sea. As a result of mixing in the entrance area, a large portion of the outflowing Baltic Sea water returns with the inflowing salty water and thus lowers the salinity of the Baltic Sea deep-water considerably. This recycling of the Baltic Sea water is a key process determining the salinity of today's Baltic Sea. The sensitivity of this recycling, and thus of the Baltic Sea salinity, to climatic changes in the freshwater supply is analyzed. A simple model is formulated for the variations of the Baltic Sea freshwater content. Historical data of the freshwater supply and the salinity in the Baltic Sea are used in the model to achieve an empirical expression relating variations of the recycling of Baltic Sea water to the variations of the freshwater supply. The recycling is found to be very sensitive to the freshwater supply. We find that an increase of freshwater supply of 30% is the level above which the Baltic Sea would turn into a lake. Recent climate modeling results suggest that river runoff to the Baltic Sea may increase dramatically in the future and thus possibly put the Baltic Sea into a new state.  相似文献   

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