Müller, A. 1997. Hydrodynamics and nutrient distribution in bottom sediments of the Archipelago Sea, southwestern Finland. Boreal Env. Res. 2(3): 229–237.
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Kaplin, C., Hemming, J. & Holmbom, B. 1997. Improved water quality by process renewal in a pulp and paper mill. Boreal Env. Res. 2(3): 239–246.
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Hanstén, C., Pekkarinen, M. & Valovirta, I. 1997. Effect of transplantation on the gonad development of the freshwater pearl mussel, Margaritifera margaritifera (L.). Boreal Env. Res. 2(3): 247–256
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Kankaanpää, H., Korhonen, M., Suortti, A.-M. & Heiskanen, A.-S. 1997. Seasonal sedimentation of organic matter and contaminants in the Gulf of Finland. Boreal Env. Res. 2(3): 257–274.
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Kløve, B. 1997. Comparison and development of ditch structures (bed pipe barriers) in reducing suspended solids concentration in waters flowing from peat mining sites. Boreal Env. Res. 2(3): 275–286.
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Inkala, A., Bilaletdin, Ä. & Podsetchine, V. 1997. Modelling the effect of climate change on nutrient loading, temperature regime and algal biomass in the Gulf of Finland. Boreal Env. Res. 2(3): 287–301.
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Pers, C., Danielsson, Å. & Rahm, L. 1997. Statistical modelling of phosphate variations in the Baltic proper. Boreal Env. Res. 2(3): 303–315.
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Müller, A. 1997. Hydrodynamics and nutrient distribution in bottom sediments of the Archipelago Sea, southwestern Finland. Boreal Env. Res. 2(3): 229–237.
The distribution of nutrients (i.e. water contents, organic carbon, nitrogen and phosphate concentrations) was investigated in the upper 20 cm of coastal marine sediments off southwestern Finland. Bottom sediments were sampled along a transect from the Aurajoki river mouth to the open Archipelago Sea. Towards the Archipelago Sea, sediments showed increasing water and organic carbon contents and decreasing C/N ratios. Phosphate values in the sediments did not show any significant variation along the transect, but increased towards the surface. Most sediments were classified as mud. Resuspension processes can be expected to be dominant in the harbour. Organic carbon contents increase as a result of lateral transport of the lighter fraction towards the more distal stations. Sedimentation is greatest in the small but deep basins in the more distal regions of the transect. The decrease in C/N ratios may be due to the reduced importance of denitrification during the decay of organic matter. Oxygen depletion increases in the sediments because of higher organic carbon contents at the outer stations. Phosphate values increase towards the sediment surface, possibly indicating upward diffusion of phosphorus. Phosphorus depleted surface waters of the Baltic Sea may show greater influence with increasing distance from the harbour. This may be compensated for the higher proportion of fine material which can bind phosphate at the more distal sampling stations.
Kaplin, C., Hemming, J. & Holmbom, B. 1997. Improved water quality by process renewal in a pulp and paper mill. Boreal Env. Res. 2(3): 239–246.
The Kaukas pulp and paper mill on southern Lake Saimaa was investigated to evaluate the environmental benefits of process renewal, i.e. the substitution of chlorine by chlorine dioxide in the bleaching and the modernisation of the biological effluent treatment. A comparative study of the mill effluent and the catchment water area was performed before (1991) and after (1993/1995) the changes. The chemical composition of the mill effluent was analysed with special emphasis on chlorinated organics and wood extractives. The same compounds were analysed in lake waters with respect to distribution and persistence. The study revealed a considerable decrease in the concentrations of chlorinated organics both in the mill discharge and in the lake. Most wood extractives also decreased in the effluent. However, the discharge of some wood extractives, such as sitosterol, was not significantly affected by the changes.
Hanstén, C., Pekkarinen, M. & Valovirta, I. 1997. Effect of transplantation on the gonad development of the freshwater pearl mussel, Margaritifera margaritifera (L.). Boreal Env. Res. 2(3): 247–256.
In Margaritifera margaritifera (L.) individuals collected from the Ähtävänjoki river in July 1988, the histological structure of the pre-spawn ovaries and testes was neat, and a normal reproductive capacity could be predicted. The sex ratio was even, and no true hermaphrodites were present. The commonly occurring "microhermaphrodite" gonads with small nests of the germ cells of the opposite sex may show that the mussels are capable of hermaphroditism or sex reversal. The experimental transplantation of freshwater pearl mussels for conservation purposes 10 km upstream in the same river in 1987 did not disturb the mussels' gonad development. This was assessed from examination of the histological structure of the gonads in July, a year after the transfer. The sizes of testis follicles, the numbers of sperm morulae and oocytes per follicle, the occurrence of microhermaphrodite or out-of-phase follicles were similar both in endemic and transplanted mussels. From these results it could be concluded that transplantation of freshwater pearl mussels can be undertaken in a home river without reducing the gamete producing capacity of the mussels during the breeding season of the next year.
Kankaanpää, H., Korhonen, M., Suortti, A.-M. & Heiskanen, A.-S. 1997. Seasonal sedimentation of organic matter and contaminants in the Gulf of Finland. Boreal Env. Res. 2(3): 257–274.
The levels of organic contaminants were analyzed in the accumulating material of the Gulf of Finland from April to October in 1996. Settling particles were collected at two locations: GF2 (open sea), and Schepelev (Neva Bay). The contaminants included in the study were: PCBs (7 congeners), DDT and its metabolites, HCHs, chlordanes, trans-nonachlor, and HCB. Sedimentation of total oil and total organic halogens (EOX) was also quantified. The average fluxes of the chemicals were calculated, and the total sedimentation to the whole Gulf of Finland accumulation areas were extrapolated from the flux values obtained for one open sea station. The sedimentation of total particulate carbon, nitrogen and phosphorus was also measured. The contribution of phytoplankton carbon (PPC) and other biogenic material to the total settled carbon was estimated. The sedimentation of the compounds was most intense during the times of increased dry matter accumulation. During the spring, diatoms were dominant in the settled material and phytoplankton comprised about 78% of total settled carbon. During the autumn, the effect of resuspension seemed important. The results from the trap at Schepelev indicated smaller fluxes of PCBs and DDTs than in the open Gulf, but the PCB concentration was high. With the exception of DDTs (90%), the Gulf of Finland was calculated to receive 1–9% of the reported total input of different contaminants to the Baltic Sea.
Kløve, B. 1997. Comparison and development of ditch structures (bed pipe barriers) in reducing suspended solids concentration in waters flowing from peat mining sites. Boreal Env. Res. 2(3): 275–286.
Ditch structures are used to reduce the transportation of eroded peat from peat mines during high runoff events. In this article, new types of control structures were compared with traditional ones. Two different experiments were performed under laboratory conditions. First, hydraulics were studied by determining the discharge at different water levels. Second, the effectiveness of the constructed barriers in reducing the transport of peat was measured. The results of the study show that attenuating the runoff peak by storing water in the ditch network is the most effective way of reducing the concentration of suspended solids of waters flowing from peat mining sites. The water intake location also has a small effect on the transport. The new type of control barrier retains the runoff peaks. Its outlet is situated close to the water surface where the concentration of suspended peat is less than at greater depths.
Inkala, A., Bilaletdin, Ä. & Podsetchine, V. 1997. Modelling the effect of climate change on nutrient loading, temperature regime and algal biomass in the Gulf of Finland. Boreal Env. Res. 2(3): 287–301.
Climate changes and the potential related warming can change runoff, nutrient transport, mean wind velocities and water temperatures. These changes will further affect algal growth in a way that can be modelled. The changes to the nutrient load, temperature regime and algal biomass were simulated by three separate models. The simulations were made for the years 2020, 2050 and 2090. The simulated temperature variations and nutrient loading dynamics were used by algal model to predict changes of the algal biomass under the three different climate scenarios. According to the different scenarios, the maximum temperature of the surface water increased by 0.3–6.2 °C, but in the deeper waters (> 40 m) by less than 0.1 °C. The major part of the nutrient loads is anthropogenic and this part did not change in the scenarios. Thus, the changes in the algal biomass were also relatively small. However, the timing and quantity of spring bloom did change noticeably, at most in 2090, two weeks earlier and 20% higher than nowadays.
Pers, C., Danielsson, Å. & Rahm, L. 1997. Statistical modelling of phosphate variations in the Baltic proper. Boreal Env. Res. 2(3): 303–315.
A statistical model of the variation of phosphate concentration in the upper layers of the Baltic proper was formed, with the aim of studying the magnitude of this variation and to be able to adjust corrupted time series. The large variation observed is only partially explained by seasonal variations and geographical structures. Despite inclusion of long-term trends and annual variations, the residuals showed a substantial correlation within and between the time series.