The Baltic Sea Experiment BALTEX: A brief overview and some selected results of the authors

The mechanisms responsible for the transfer of energy and water within the climate system are under worldwide investigation within the framework of the Global Energy and Water Cycle Experiment (GEWEX) to improve the predictability of natural and man-made climate changes at short and long ranges and their impact on water resources. Five continental-scale experiments have been established within GEWEX to enable a more complete coupling between atmospheric and hydrological models. One of them is the Baltic Sea Experiment (BALTEX).In this paper, the goals and structure of BALTEX are outlined. A short overview of measuring and modelling strategies is given. Atmospheric and hydrological model results of the authors only are presented. These include also the validation of precipitation using station measurements as well as validation of modelled cloud cover with cloud estimates from satellite data. Furthermore, results of a large-scale grid based hydrological model to be coupled to atmospheric models are presented.This research has never been possible without the contribution of research groups and operational institutions from all 10 member countries. We concentrate here on results obtained at the GKSS research center.     

Some results of bottom sediment monitoring in oil production area in the southeastern Baltic Sea

Monitoring studies in the area of Kravtsovskoe oil field in the southeastern Baltic Sea have been carried out since 2003. Terrigenous bottom sediments (0–5 cm layer) in the area (23 stations) are represented by all grain size types. Down to the depth of 30–50 m, these are mostly quartz sands; at depths of 60–110 m, these are terrigenous mud with C_org content of 1–3%. The concentration and distribution of toxic elements (Cu, Co, Cd, Pb, Ba, and Hg) over sediment types and bed area are the same as in the Baltic Sea as a whole: Cu, Co, Cd, Pb, and, partially, Hg are distributed in accordance with the “fraction rules” (with minimums in sands and coarse aleurites and maximums in mud); Ba distribution is independent of the sediment type. The concentrations of toxic elements tend to increase with time: the concentrations of such elements in samples (at the same stations) somewhat increase compared with their concentrations before the construction of D-6 oil platform, during its construction, and during oil production. This trend in the concentrations of toxic elements in sediments can be due to the steelwork of D-6 platform. The increase in Ba concentration is likely due to drill mud spills during exploration drilling. None of the elements shows sediment pollution in excess of MAC anywhere in the area.     

Atmospheric input of nitrogen into the North Sea: ANICE project overview

The aim of the atmospheric nitrogen inputs into the coastal ecosystem (ANICE) project is to improve transport–chemistry models that estimate nitrogen deposition to the sea. To achieve this, experimental and modelling work is being conducted which aims to improve understanding of the processes involved in the chemical transformation, transport and deposition of atmospheric nitrogen compounds. Of particular emphasis within ANICE is the influence of coastal zone processes. Both short episodes with high deposition and chronic nitrogen inputs are considered in the project. The improved transport–chemistry models will be used to assess the atmospheric inputs of nitrogen compounds into the European regional seas (the North Sea is studied as a prototype) and evaluate the impact of various emission reduction strategies on the atmospheric nitrogen loads. Assessment of the impact of atmospheric nitrogen on coastal ecosystems will be based on comparisons of phytoplankton nitrogen requirements, other external nitrogen inputs to the ANICE area of interest and the direct nitrogen fluxes provided by ANICE. Selected results from both the experimental and modelling components are presented here. The experimental results show the large spatial and temporal variability in the concentrations of gaseous nitrogen compounds, and their influences on fluxes. Model calculations show the strong variation of both concentrations and gradients of nitric acid at fetches of up to 25 km. Aerosol concentrations also show high temporal variability and experimental evidence for the reaction between nitric acid and sea salt aerosol is provided by size-segregated aerosol composition measured at both sides of the North Sea. In several occasions throughout the experimental period, air mass back trajectory analysis showed connected flow between the two sampling sites (the Weybourne Atmospheric Observatory on the North Norfolk coast of the UK and Meetpost Noordwijk, a research tower at 9 km off the Dutch coast). Results from the METRAS/SEMA mesoscale chemistry transport model system for one of these cases are presented. Measurements of aerosol and rain chemical composition, using equipment mounted on a commercial ferry, show variations in composition across the North Sea. These measurements have been compared to results obtained with the transport–chemistry model ACDEP which calculates the atmospheric inputs into the whole North Sea area. Finally, the results will be made available for the assessment of the impact of atmospheric nitrogen on coastal ecosystems.     

An evaluation and implementation of the regional coupled ice-ocean model of the Baltic Sea

Ocean Dynamics - A three-dimensional, regional coupled ice-ocean model based on the open-source Community Earth System Model has been developed and implemented for the Baltic Sea. The model...     

Environmental responsibility and co-operation between Baltic and North Sea municipalities: Part 1: The Baltic Eco-Cities programme and its pilot function for the municipalities bordering the North Sea

National governments have greater legislative authority than local governments in marine environmental protection, on the global basis, but local governments both invest more money than national governments in environmental protection and often execute more environmental policies. When national governments have established regional marine resources management programmes, e.g. the Baltic, the Mediterranean, or the Great Lakes region, the final remediation planning responsibility has ultimately been delegated to local authorities.

The United Nations Conference on Environment and Development held in Rio de Janeiro in June 1992 did not consider this dichotomy and the International Council for Local Environmental Initiatives (ICLEI) and a coalition of other local government associations are considered to have a role within the two sectors, national governments and non-governmental organizations. Chapter 17 of Agenda 21 on Protection of the Oceans gives little attention to the primary role presently being played by the local authorities in controlling marine pollution. Chapter 17 states that 70% of the marine pollution comes from land-based sources, and that more than half of the world's population is settled in coastal communities. But the Chapter does not present the fact that local authorities are the primary force in organizing and managing the coastal settlements concerning the greatest sources of marine pollution. The role of local authorities in Agenda 21 and the partnership between the international community and local authorities to achieve Agenda 21 objectives must be defined.     

Loading effects in Metsähovi from the atmosphere and the Baltic Sea

Loading by atmosphere and by the Baltic Sea cause gravity change at Metsähovi, located 15 km from the open sea. Gravity is changed by both the Newtonian attraction of the loading mass and by the crustal deformation. We have performed loading calculations using appropriate Green's function for both gravity and deformation, for both atmospheric and Baltic loading. The loading by atmosphere has been computed using a detailed surface pressure field from high resolution limited area model (HIRLAM) for north Europe up to 10° distances. Baltic Sea level is modelled using tide gauge records. Calculations show that 1 m of uniform layer of water corresponds to 31 nm s⁻² in gravity and −11 mm in height. Modelled loading is compared with observations of the superconducting gravimeter T020 for years 1994–2002. The combination of HIRLAM and a tide gauge record decreases RMS of gravity residuals by 14% compared to single admittance in air pressure corrections without sea level data. Regression of gravity residuals on the tide gauge record at Helsinki (at 30 km distance) gives a gravity effect of 26 nm s⁻² m⁻¹ for Baltic loading.The gravity station is co-located with a permanent GPS station. We have also associated the loading effects of the atmosphere and of the Baltic Sea with temporal height variations. The range of modelled vertical motion due to air pressure was 46 mm and that due to sea level 18 mm. The total range was 38 mm. The effects of the Baltic Sea and of the atmosphere partly cancel each other, since at longer periods the inverse barometer assumption is valid. Regression of the modelled height on local air pressure gives −0.37 mm hPa⁻¹, corresponding approximately to width 6° for pressure system.We have tested the models using one year of daily GPS data. Multilinear regression on local air pressure and sea level in Helsinki gives the coefficient −0.34 mm hPa⁻¹ for pressure, and −11 mm m⁻¹ for sea level. These match model values. Loading by air pressure and Baltic Sea explains nearly 40% of the variance of daily GPS height solutions.     

The future of the western Baltic Sea: two possible scenarios

Globally coupled climate models are generally capable of reproducing the observed trends in the globally averaged atmospheric temperature. However, the global models do not perform as well on regional scales. Here, we present results from four 100-year, high-resolution ocean model experiments (resolution less than 1 km) for the western Baltic Sea. The forcing is taken from a regional atmospheric model and a regional ocean model, imbedded into two global greenhouse gas emission scenarios, A1B and B1, for the period of 2000 to 2100 with each two realisations. Two control runs from 1960 to 2000 are used for validation. For both scenarios, the results show a warming with an increase of 0.5–2.5 K at the sea surface and 0.7–2.8 K below 40 m. The simulations further indicate a decrease in salinity by 1.5–2 practical salinity units. The increase in water temperature leads to a prolongation of heat waves based on present-day thresholds. This amounts to a doubling or even tripling of the heat wave duration. The simulations show a decrease in inflow events (barotropic/baroclinic), which will affect the deepwater generation and ventilation of the central Baltic Sea. The high spatial resolution allows us to diagnose the inflow events and the mechanism that will cause future changes. The reduction in barotropic inflow events correlates well with the increase in westerly winds. The changes in the baroclinic inflows can be consistently explained by the reduction of calm wind periods and thus a weakening of the necessary stratification in the western Baltic Sea and the Danish Straits.     

Ecotoxicity assessment of natural attenuation effects at a historical dumping site in the western Baltic Sea

During the late 1950s and early 1960s of the past century, industrial waste material highly enriched in various contaminants (heavy metals, PAHs) was dumped in the inner Mecklenburg Bay, western Baltic Sea. Large-scale shifts in the spatial distribution of heavy metals in surface sediments were mapped by geochemical monitoring in the mid-1980s and 12 years later in 1997. A further study in 2001 was designed to investigate the small-scale spatial distribution of contaminants inside, on top of, and around the historical dumping ground and to examine possible effects to benthic organisms (Arctica islandica, microbiological toxicity tests). The site is located within an area characterized by a discontinuous deposition of fine sediments, but net sedimentation rate of about 3mm/y led ultimately to a gradual coverage of the dumped material. During the first decades after the dumping, about half of the originally dumped material was already spread over the surrounding area as a result of sediment dynamics and re-suspension processes. Recent sediments of the historical dump site are still significantly enriched in heavy metals and PAHs. Microbiological toxicity test results were positive, though uptake of contaminants in mussels was found to deviate only slightly from that of a non-contaminated reference station due to a gradual dilution and decrease in bioavailability of the contaminants.     

The distribution of several organochlorine compounds in the Baltic Sea

Summary On a cruise, covering the whole Baltic Sea area, in May/June 1983, from the Kattegat through the Belt Sea, the Baltic Proper, and the Gulfs of Finland and Bothnia, investigations concerning the distribution of several organochlorine compounds were made. In accordance with the water exchange in the Kattegat and Belt Sea, a vertical stratification can be seen for -, -, -HCH and DDT — with higher concentrations in the outflowing surface water with low salinity and lower values in the inflowing bottom water with high salinity. The bottom water concentrations in the Kattegat and Belt Sea are increasing from North to South by mixture with surface water. East of the Darss Sill, the distribution pattern becomes more homogeneous with only slight differences in the average mean concentrations between the various basins forming the Baltic Sea.

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Über die Verteilung einiger Organochlorverbindungen in der Ostsee

Zusammenfassung Im Wasser des Kattegats, der Beltsee, der zentralen Ostsee, des Finnischen Meerbusens und der Bottensee wurden im Mai und Juni 1983 Untersuchungen auf Organochlorverbindungen vorgenommen. In Übereinstimmung mit den Verhältnissen des Wasseraustausches im Kattegat und der Beltsee kann man für -, -, -HCH und DDT eine vertikale Schichtung erkennen — mit höheren Konzentrationen im abfließenden Oberflächenwasser mit niedrigem Salzgehalt und niedrigeren Werten im einströmenden Bodenwasser mit hohem Salzgehalt. Durch Vermischung mit dem Oberflächenwasser steigen die Konzentrationen im Bodenwasser im Kattegat und der Beltsee von Norden nach Süden hin an. Östlich der Darsser Schwelle ergibt sich eine gleichmäßigere Verteilung mit nur geringen Unterschieden in den mittleren Konzentrationen innerhalb der einzelnen Becken, die die Ostsee bilden.

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De la distribution de quelques composants organochlorés dans la mer Baltique

Résumé En mai et juin 1983 des recherches sur la distribution de plusieurs composants organochlorés furent effectuées durant une campagne couvrant le Kattegat, les Belts, la mer Baltique centrale, les Golfes de Finlande et de Bothnie. En accord avec les échanges des eaux dans le Kattegat et les Belts, une stratification verticale de l'-, -, -HCH et DDT fut mise en évidence, avec une concentration plus forte dans les eaux superficielles sortantes et des valeurs plus faibles dans les eaux de fond entrantes. A l'Est du seuil de Drss, la répartition des échantillons devient plus homogène avec seulement de légères différences des concentrations moyennes entre les différents bassins qui forment la mer Baltique.

     

Exploitation of biological resources of the Baltic Sea by estonia in 1928–1995

The main exploitable biological resources in the Estonian zone of the Baltic Sea are fish stocks. Fishes of marine origin constitute the main bulk (on the average 91%) of catches. Some freshwater and migratory fishes, having usually only marginal role in the total weight of fish landings, are of special importance for local fishermen in certain regions. Other living resources — red algae and seals-have been exploited in rather small amounts.The main factors having controlled changes in the condition of fish stocks and catches are natural conditions, marine pollution, eutrophication and exploitation rate.     

Physical and chemical variability of the Baltic Sea: a joint experiment in the Gotland Basin

An area of 25 × 30 nmi with a subarea of 20 × 20 nmi in the Baltic Sea Gotland Basin was surveyed for about one month by vertical CTD and fluorometric chlorophyll a casts, and by towed profiles with a chemical profiler (nutrients, CTD, O₂, pH) and an undulating CTD. Autonomous current meter data were available for the same period.Five CTD surveys with a 5-mile spacing showed the existence of synoptic eddies and several other perturbations. A first mode eddy (with all the isopycnals lifted within the halocline) had reduced salinities in the upper layer and chlorophyll concentrations were reduced by 2 to 3-fold. A second mode eddy (with the isopycnals lifted in the top of the halocline and lowered in the bottom layers) with a diameter of 20 km was under prolonged observation. Anticyclonic currents at 96-m depth were up to 25 cm s^?1. Along the section across the eddy at 80-m depth, the mean nitrate concentration dropped from about 7 to 8 to 5 μmol dm^?3 while other chemical parameters lacked intense variations. An increased activity of the intrusive fine-structure was detected in the eddy center. The Baltic eddies are essentially non-linear, and transport water in their ‘nuclei’. An internal front, separating waters with different T,S composition, was discovered in the upper layers.The observations are discussed with respect to discovering long-term trends while monitoring the Baltic environment.     

Biomarkers of contaminant exposure: results of a field study with flounder (Platichthys flesus) from the southern Baltic Sea

The results of the present study are based on enzyme biomarker measurements in flounder (Platichthys flesus), a flatfish species that is widely distributed in Baltic coastal waters. The fish were collected from known pollution gradients and from reference areas regarded as relatively free of anthropogenic input. Muscular cholinesterases (ChEs), hepatic glutathione S-transferase (GST), and hepatic ethoxyresorufin-O-deethylase (EROD) activities were measured in each sampled specimen of flounder. Generalized linear models (GLM) were used to analyze the dependence of the enzyme activity on sampling year and area as well as on the biological parameters of the fish. Statistically significant differences in the activities of the measured biomarkers were observed between reference and contaminated sites. ChEs and GST activities differed with gender. The results of this study suggest that the location and year of sampling have a significant impact on the activity of all the measured biomarkers.     

Toward a sustainable estuary in north carolina's albemarle and pamlico sounds: Some implications for the Baltic Sea

A major task in developing a management strategy for the Baltic Sea will be the establishment of a program that adheres to the philosophy of sustainable use and is capable of implementation. For many nations this has proven to be a very difficult task marked with successes and failures. This paper discusses North Carolina's attempts to move toward sustainability in its Albemarle and Pamlico estuaries. The paper concludes with some lessons learned that could be helpful to the Baltic region as it strives for sustainability.     

HELCOM Baltic Sea Action Plan - A regional programme of measures for the marine environment based on the Ecosystem Approach

The Helsinki Commission (HELCOM) Baltic Sea Action Plan, adopted by the coastal countries of the Baltic Sea and the European Community in November 2007, is a regional intergovernmental programme of measures for the protection and management of the marine environment explicitly based on the Ecosystem Approach. The Action Plan is structured around a set of Ecological Objectives used to define indicators and targets, including effect-based nutrient input ceilings, and to monitor implementation. The Action Plan strongly links Baltic marine environmental concerns to important socio-economic fields such as agriculture and fisheries and promotes cross-sectoral tools including marine spatial planning. Due to complementarities with the European Union (EU) Marine Strategy Framework Directive, the Action Plan is in essence a pilot for this process without neglecting the important role of the Russian Federation - the only Baltic coastal country not a member of the EU.