Paatero, J. & Hatakka, J. 1999. Wet deposition efficiency of short-lived radon-222 progeny in central Finland. Boreal Env. Res. 4: 285–293.
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Ignatieva, N.V. 1999. Nutrient exchange across the sediment–water interface in the eastern Gulf of Finland. Boreal Env. Res. 4: 295–305.
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Stipa, T. 1999. Water exchange and mixing in a semi-enclosed coastal basin (Pohja Bay). Boreal Env. Res. 4: 307–317.
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Müller, A. 1999. Distribution of heavy metals in recent sediments in the Archipelago Sea of southwestern Finland. Boreal Env. Res. 4: 319–330.
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Hurme, T.S. & Puhakka, J.A. 1999. Characterization and fate of polychlorinated biphenyl contaminants in Kernaalanjärvi sediments. Boreal Env. Res. 4: 331–342.
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Joensuu, S., Ahti, E. & Vuollekoski, M. 1999. The effects of peatland forest ditch maintenance on suspended solids in runoff. Boreal Env. Res. 4: 343–355.
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Inkala, A. & Pitkänen, H. 1999. The effect of load reductions on algal biomass in the eastern Gulf of Finland estimated by the FINNALGA model. Boreal Env. Res. 4: 357–366.
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Antsulevich, A.E., Maximovich, N.V. & Vuorinen, I. 1999. Population structure, growth and reproduction of the common mussel (Mytilus edulis L.) off the Island of Seili (SW Finland). Boreal Env. Res. 4: 367–375.
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Johnsen, K., Tana, J., Lehtinen, K.-J. & Carlberg, G.E. 1999. Biomarker responses in fish exposed to effluent from bleached sulphite pulp production. Boreal Env. Res. 4: 377–386.
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Westman, K., Savolainen, R. & Pursiainen, M. 1999. Development of the introduced North American signal crayfish, Pacifastacus leniusculus (Dana), population in a small Finnish forest lake in 1970–1997. Boreal Env. Res. 4: 387–407.
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Paatero, J. & Hatakka, J. 1999. Wet deposition efficiency of short-lived radon-222 progeny in central Finland. Boreal Env. Res. 4: 285–293.
Ignatieva, N.V. 1999. Nutrient exchange across the sediment–water interface in the eastern Gulf of Finland. Boreal Env. Res. 4: 295–305.
Stipa, T. 1999. Water exchange and mixing in a semi-enclosed coastal basin (Pohja Bay). Boreal Env. Res. 4: 307–317.
Müller, A. 1999. Distribution of heavy metals in recent sediments in the Archipelago Sea of southwestern Finland. Boreal Env. Res. 4: 319–330.
Hurme, T.S. & Puhakka, J.A. 1999. Characterization and fate of polychlorinated biphenyl contaminants in Kernaalanjärvi sediments. Boreal Env. Res. 4: 331–342.
Joensuu, S., Ahti, E. & Vuollekoski, M. 1999. The effects of peatland forest ditch maintenance on suspended solids in runoff. Boreal Env. Res. 4: 343–355.
Inkala, A. & Pitkänen, H. 1999. The effect of load reductions on algal biomass in the eastern Gulf of Finland estimated by the FINNALGA model. Boreal Env. Res. 4: 357–366.
Antsulevich, A.E., Maximovich, N.V. & Vuorinen, I. 1999. Population structure, growth and reproduction of the common mussel (Mytilus edulis L.) off the Island of Seili (SW Finland). Boreal Env. Res. 4: 367–375.
Johnsen, K., Tana, J., Lehtinen, K.-J. & Carlberg, G.E. 1999. Biomarker responses in fish exposed to effluent from bleached sulphite pulp production. Boreal Env. Res. 4: 377–386.
Westman, K., Savolainen, R. & Pursiainen, M. 1999. Development of the introduced North American signal crayfish, Pacifastacus leniusculus (Dana), population in a small Finnish forest lake in 1970–1997. Boreal Env. Res. 4: 387–407.
The washout efficiency of 214Pb, a short-lived daughter nuclide of 222Rn, was studied by measuring external gamma radiation at Tikkakoski, Central Finland, in 1995. A mean washout ratio (volume per volume) of 1.2 x 106 was obtained in this study. According to the results, rain removes airborne 214Pb more efficiently than snow, which is in agreement with earlier studies. Higher washout ratio values were encountered during afternoon hours than during early morning hours, a result which is associated with the better vertical mixing of the lower troposphere during afternoon hours. The observed inverse correlation between washout ratio and rain intensity supports the earlier results that below-cloud scavenging processes are less efficient removal mechanisms of airborne 214Pb compared to in-cloud processes. The highest washout ratios were measured during westerly winds, which are usually associated with cyclones travelling from the North Atlantic Ocean in an easterly direction. The results obtained in this study can also be applied to fallout estimates of wet-depositing chemical substances, e.g. airborne sulphate or heavy metals, for which equivalent remote-sensing methods, such as that involving gamma radiation in this case, may not be available.
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Benthic nutrient fluxes (sedimentation, degradation and burial within the sediment, and release to the water column) were estimated for a series of stations in the Neva Bay and different areas of the eastern Gulf of Finland (GOF). It was shown, that the Gulf sediments act as an efficient trap for both nutrients: 20%–50% of P and 40%–65% of N in the Neva estuary and in the open Gulf, and up to 100% in the Neva Bay are buried within the accumulating sediment. The rest is released to the overlying water. Minor portion of dissolved nutrients is released by molecular diffusion from the deep sediment layers. The diffusion from immediate sediment-water interface and convective transport seem to be of greater importance in nutrient release. The variations in the intensity of benthic processes of nutrient sedimentation, adsorption, minerals formation, nitrification, denitrification and convective transport from the sediments in the sub-areas of the Gulf are generally determined by the chemical composition and amount of sedimenting material, in combination with bottom dynamics. Benthic nutrient flux to the overlying water could supply generally a small fraction of estimated phytoplankton nutrient demand (0%–10% of P and 1%–5% of N).
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The processes contributing to the deep water renewal and oxygen balance of Pohja Bay are reviewed here, with reference to the extensive experimental material from the years 1990–1993. The observations reveal previously unreported frequent minor inflows of sea water into the bay. A one-dimensional diffusion model is introduced and applied to computation of the diffusion-corrected biological oxygen sink during apparent deep water stagnation periods; the sink is evaluated as 0.06 ± 0.01 mg l–1 d–1. The results are summarized in a conceptual description of the physical processes underlying the estuarine circulation and oxygen balance of the bay.
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The distributions of organic carbon, sulphur, phosphate, and heavy metals (Ni, Co, Cu, Zn, Pb, Cd, Mn, Fe) were analyzed in marine surface sediments in the Archipelago Sea of southwestern Finland. Variations in heavy metal contents are caused mainly by physical not chemical processes. Lateral transport processes of particulate matter, including organic matter, strongly influence the distribution pattern of heavy metals in the study area. In addition, variable environmental conditions between stations contribute to differences in heavy metal contents. In the harbor, close to the mouth of the Aurajoki, there is a relatively high potential for the binding of heavy metals by oxides/hydroxides. In contrast, sulphide precipitations of heavy metals in the sediments may become relatively more important with increasing water depth, i.e. towards the outer Archipelago Sea. For chromium, aluminium, titanium and vanadium detrital binding was considered to be dominant.
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Polychlorinated biphenyl (PCB) content and distribution of individual PCB congeners in sediment samples from Kernaalanjärvi, a lake in Finland, were determined with a gas chromatography-electron/capture detection (GC-ECD) technique. Three different extraction methods with hexane–acetone mixture were tested. Neither extended extraction time (1 day vs. 10 days) nor sonication increased the recovery of PCBs from the aged sediments. For freshly spiked PCBs the extraction efficiency was 93% ± 2% (w/w). Total PCB concentrations ranging from 0.5 to 10.7 mg kg–1 d.w. were measured in Kernaalanjärvi sediment samples from the 2–15 cm depth. Comparison of PCB discharge documentation to congener distribution patterns in sediments suggested selective removal of lower chlorinated PCBs by physical processes. There was no evidence of in situ biotransformations of PCBs by indigenous sediment microorganisms. Presence of potentially toxic mono- and di-ortho chlorinated coplanar PCBs in sediments resulted in estimated 2,3,7,8-TCDD (tetrachlorodibenzo-p-dioxin) toxic equivalents between 15 and 301 ng kg–1 d.w.
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In 1990–1994, the effect of peatland forest ditch maintenance on the concentration of suspended solids in runoff water was studied in Finland in 37 catchments by using a short pre-treatment period and comparing with 31 control areas. On the average, the concentrations of suspended solids were 4–5 mg l–1 in the control areas and in the treatment areas before ditch network maintenance. During a period of 1–3 years after maintenance, the concentration of suspended solids in the water leaving ditch network and entering sedimentation ponds averaged 45.8 mg l–1. The magnitude of the increase depended on the area subjected to ditch maintenance as well as the prevailing soil type at the bottom of the ditches. Measured as 1–3 year averages, only half of the sedimentation ponds reduced the concentration of suspended solids. During the first year after ditch network maintenance, the suspended solids concentration in the water entering the sedimentation ponds averaged 71.3 mg l–1 and the water leaving the ponds 58.1 mg l–1. In the second year, the corresponding values were 26.8 mg l–1 and 21.1 mg l–1 and in the third year, 12.8 mg l–1 and 12.4 mg l–1, respectively.
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Eutrophication and algal blooms are major environmental problems in the Gulf of Finland. One possible way to approach the problem is mathematical modelling. If the most important processes are successfully modelled, it is possible to calculate the effects of human activity. The application of an ecological model to the eastern Gulf of Finland is presented here. The algal model used is coupled with a 3-dimensional hydrological one. The application year used was 1994 and the validation year 1995. The load reductions used are based on the recommendation of HELCOM or a more realistic assessment. Results received indicate, that clear effects can be observed even within a short period. According to our model the reduction of phosphorus load is important near river entrances, while for the open eastern Gulf of Finland nitrogen is more important.
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We studied the reproduction, population structure and growth of the common mussel (Mytilus edulis L.) off the Island of Seili in summer 1996. The discharge of gametes occurred from 26 July to 2 August. The breeding period was short and repeated spawning was not found. Density of mussels ranged from 1 250 to 16 730 ind. m–2 and biomass from 250 to 2 100 g m–2. Size of individuals (shell length) ranged from 0.6 mm (spat) to 44.0 mm (nine years old). The distribution of age groups in the mussel population demonstrates the stability of recruitment over several previous years. The most rapidly growing individuals (reaching up to 41 mm at the end of the seventh year) were registered at the depth of 8 m. The average growth rate of molluscs from different habitats did not vary. A Bertalanffy model of ontogenetic growth, based on seasonal changes in the water temperature, was constructed for the “average individual” of this population.
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The effects of biologically treated effluents from bleached sulphite pulp production were studied using brown trout (Salmo trutta) as test organism. Continuous-flow exposures under laboratory conditions were conducted at two dilutions (1:40 and 1:400) for eight weeks, followed by a six-week recovery period. Physiological and biochemical biomarkers including liver histology, hematology and hepatic enzyme assays were used and the exposure was verified by analysing fish bile and fish tissue concentrations of resin acids and chlorophenols. The conjugated chlorophenols and resin acids levels in the exposed fish bile are considered as low. Only two significant responses were observed, both in liver function.The MFO associated EROD activity was induced parallel to lower liver glycogen levels. Otherwise, the changes in physiological parameters analysed were few as compared to reference fish. The small differences in physiological parameters between the reference group and the exposure group (1:40) after six-week recovery period show that the observed responses were reversible. The spectrum and pattern of results observed in this study are very much the same as seen in laboratory and field studies with bleached kraft mill effluents from modern mills.
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Signal crayfish (Pacifastacus leniusculus Dana) originating from Lake Tahoe, California, were introduced into a small (11 ha) lake, Iso-Majajärvi, in Central Finland (61°52´N, 23°51´E) in 1969. Since then, the population has been monitored regularly by trap catching. The stocked signal crayfish (3+ to 5+ years old) were caught until 1975, by when they reached ages of 8+ to 10+ years. First juveniles were born in 1970. Catches and population sizes were low during the study period. The catch peaked in 1983 at 0.6 ind./trap/night. The population size was estimated at 670 trappable specimens. Population size then declined, and has since fluctuated between 200 and 400 individuals. Despite annual variations, mean CPUE indicate a small, but statistically significant, increase in later years. The slow development of the P. leniusculus population has been attributed to environmental factors, especially the combination of limited area of suitable crayfish habitat and the low Ca concentration with periodic acidity. Fifty percent of the female P. leniusculus matured at ca. 84 mm. Consequently, half of the females entered the breeding population in the autumn of their third year (3+). The signal crayfish imported into Finland and stocked were infected with crayfish plague (Aphanomyces astaci), but no mortality has been recorded.
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