The carbon budget of the Baltic Sea

This paper presents the results of a comprehensive study of the Baltic Sea carbon budget. The Baltic Sea is very much influenced by terrestrial carbon input. Rivers are the largest carbon source, and their input amounts to 10.90 Tg C yr<sup>−1</sup> (Tg = 10<sup>12</sup> g) with a 37.5% contribution of organic carbon. On the other hand, carbon is effectively exported from the Baltic to the North Sea (7.67 Tg C yr<sup>−1</sup>) and is also buried in bottom sediments (2.73 Tg C yr<sup>−1</sup>). The other sources and sinks of carbon are of minor importance. The net CO<sub>2</sub> emission (1.05 Tg C yr<sup>−1</sup>) from the Baltic to the atmosphere was calculated as the closing term of the carbon budget presented here. There is a net loss of organic carbon, which indicates that the Baltic Sea is heterotrophic

Factors influencing fluffy layer suspended matter (FLSM) properties in the Odra River - Pomeranian Bay - Arkona Deep System (Baltic Sea) as derived by principal components analysis (PCA), and cluster analysis (CA)

Factors conditioning formation and properties of suspended matter resting on the sea floor (Fluffy Layer Suspended Matter - FLSM) in the Odra river mouth - Arkona Deep system (southern Baltic Sea) were investigated. <P style='line-height: 20px;'> Thirty FLSM samples were collected from four sampling stations, during nine cruises, in the period 1996-1998. Twenty six chemical properties of the fluffy material were measured (organic matter-total, humic substances, a variety of fatty acids fractions, P, N, &delta;13C, &delta;15N; Li; heavy metals- Co, Cd, Pb, Ni, Zn, Fe, Al, Mn, Cu, Cr). The so obtained data set was subjected to statistical evaluation. <P style='line-height: 20px;'> Comparison of mean values of the measured properties led to conclusion that both seasonal and spatial differences of the fluffy material collected at the stations occured. Application of Principal Component Analysis, and Cluster Analysis, to the data set amended with environmental characteristics (depth, salinity, chlorophyll <i>a</i>, distance from the river mouth), led to quantification of factors conditioning the FLSM formation. The five most important factors were: contribution of the lithogenic component (responsible for 25% of the data set variability), time dependent factors (including primary productivity, mass exchange with fine sediment fraction, atmospheric deposition, contribution of material originating from abrasion-altogether 21%), contribution of fresh autochtonous organic matter (9%), influence of microbial activity (8%), seasonality (8%)

Influence of organic compounds on the toxicity of copper and cadmium to algae cells

The effect of siderophores, cysteine and Na2EDTA in cultures of Chlorella vulgaris and Anabaena variabilis containing copper or cadmium, on the chlorophyll-a content, as well as on the rate of carbon fixation, has been investigated. Experiments on copper accumulation in Chlorella vulgaris cells grown in the presence of organic compounds have been also carried out. The siderophores, cysteine and Na2EDTA reduced the toxicity of copper and cadmium to axenic strains of algae and natural phytoplankton. No correlation between the toxic effect of copper and its bioavailability was observed

CO2 supply from the North Sea and the Baltic Sea to the North Atlantic Ocean - evidence for the continental shelf pump

Coastal and marginal seas are thought to act as a continental shelf pump transporting CO2 from the atmosphere to the open oceans. The CO2 uptake in coastal seas is triggered by high biological activity increasing the CO2 concentrations of their waters which finally are transported to the open ocean. The North Sea and Baltic Sea located in north-west Europe are connected via the Skagerrak where the Baltic Sea water first enters the North Sea. The North Sea the provides then link to the North Atlantic Ocean. Carbon budgets for the Baltic Sea and the North Sea will be presented in order to provide evidence that in both seas the transfer of CO2, i.e. the continental shelf pump, acts in two different, but characteristic pattern. The Baltic Sea as a brackish water system collects river water and one might even call it as an estuarine system in a broader sense. Two major drainage areas provide the fresh water supply to the Baltic Sea: The Scandinavian shield supply CO2 –poor waters and the north-east European continent CO2 –rich waters. During the transport of Baltic Sea water to the North Sea the CO2 concentrations increase continuously. Riverine inputs in part control primary production in the Baltic Sea, however the major control mechanism is the winter nutrient concentrations. These are established by an interaction of production, remineralisation, export and riverine and atmospheric inputs on decadal time scale because of the residence time of the Baltic Sea water of approximately 25years. The Baltic Sea thus acts as a continental shelf pump for atmospheric CO2 which injects CO2-rich water to the Atlantic Ocean (injection pump). In contrast the North Sea water is renewed once to twice per year most notably by water from the North Atlantic Ocean. The major control mechanism of the biological activity in the North Sea are thus the continuous (and - in comparison to the Baltic Sea - high) nutrient inputs for the North Atlantic Ocean. For the CO2 export from the North Sea to the Atlantic Ocean this means that the water is enriched by CO2 during its 6-12 month travel through the North Sea. Having in mind that almost no burial occurs in the North Sea, the North Sea acts as a continental shelf pump for atmospheric CO2 by increasing the CO2 concentrations in the Atlantic waters while they are bypassing through the North Sea (bypass-pump)

Combined dynamics of mercury and terrigenous organic matter following impoundment of Churchill Falls Hydroelectric Reservoir, Labrador

Sediments from two recently (40 years) flooded lakes (Gabbro lake and Sandgirt lake) and an unflooded lake (Atikonak lake) were sampled to investigate the effects of reservoir impoundment on mercury (Hg) and terrigenous organic matter (TOM) loading in the Churchill Falls Hydroelectric complex in Labrador, Canada. Lignin biomarkers in TOM, which exclusively derive from terrestrial vegetation, were used as biomarkers for the presence and source origin of TOM—and for Hg due to their close associations—in sediments. In the two flooded Gabbro and Sandgirt lakes, we observed drastic increases in total mercury concentrations, T-[Hg], in sediments, which temporally coincided with the time of reservoir impoundment as assessed by 210Pb age dating. In the natural Atikonak lake sediments, on the other hand, T-[Hg] showed no such step-increase but gradually and slowly increased until present. T-[Hg] increases in lake sediments after flooding were also associated with a change in the nature of TOM: biomarker signatures changed to typical signatures of TOM from vegetated terrestrial landscape surrounding the lakes, and indicate a change to TOM that was much less degraded and typical of forest soil organic horizons. We conclude that T-[Hg] increase in the sediments of the two flooded reservoirs was the result of flooding of surrounding forests, whereby mainly surface organic horizons and upper soil horizons were prone to erosion and subsequent re-sedimentation in the reservoirs. The fact that T-[Hg] was still enriched 40 years after reservoir impoundment indicates prolonged response time of lake Hg and sediment loadings after reservoir impoundments