Viemärin päässä Kotkan kaupunki : Vesiensuojelun kehitys Kymijoen itäisen päähaaran suulla 1945-1970

The focus of this thesis is the marine environmental history of the eastern part and the estuary of the Kymi river from 1945 to 1970. There is no previous research on this area from an environmentally historical perspective, nor have many of the sources here discussed been previously used. Therefore the thesis expands academic understanding of local environmental processes and protection in and around the city of Kotka and the Kymi river. The thesis falls within the methodological field of socio-political history, as the research focus is centered on the local process of establishing the nature of environmental problems and solving them. The principal assumption has been that the city of Kotka, due to its ongoing expansion, was slow to respond to environmental hazards. The Kymi river was among the most degraded bodies of water during this period. Kotka on the other hand was a major center of wood processing industry and one of Finlands major industrial ports. In the past the river and its estuary had provided ample resources for fishers. It is this contradictory use of the environment that allows one to discuss the local struggle for the correct use of the environment. Primary sources include local and city archives, environmental studies, and legal documents linked with the above. The archives of the city of Kotka and of various private associations form the core sources. Environmental studies from the research period have been dealt with as sources to the local political power struggle. Alongside with current environmental research they also provide insight into the state of the environment. Another goals has been to accumulate environmental research for a future multidisciplinary study in this area. As a final conclusion it can be said that environmental degradation was widely understood as a problem only in the 1960s. The influential role of the city of Kotka however determined the pace with which these problems were then solved.

Chemical characteristics and behaviour of sediment phosphorus in the northeastern Baltic Sea.

Chemical characteristics and behaviour of sediment phosphorus in the northeastern Baltic Sea Eutrophication is a severe environmental problem in the Baltic Sea, especially in the Gulf of Finland and the Archipelago Sea, and it is enhanced by the release of phosphorus (P) from bottom sediments. The release of P from sediment reserves largely depends on the occurrence of P in different chemical forms and on the prevailing conditions, especially on the presence of oxygen. This study examines the chemical character and the vertical distribution of sediment P in two shallow estuaries, in shallow coastal sediments overlain by oxic near-bottom water, and in poorly oxygenated open sea sediments in the northeastern Baltic Sea. The objective was to evaluate how much of the sediment P is buried and removed from the nutrient cycle, and how much of it is in forms that can be released from the sediment to the overlaying water over time. Relationships between the distribution of the different P forms and the chemical and physical properties of the sediment, sediment pore water, and near-bottom water were determined in order to examine the behaviour of P at the sediment-water interface. The results show that the chemical character of sediment P varied in the different areas. Generally, in the outer estuaries and in the organic-rich coastal areas in the eastern Gulf of Finland, the sediments were higher in P than the sediments in the poorly oxygenated open sea areas in the central and western Gulf. The estuary sediments that received erosion-transported material were characterised by P bound to hydrated oxides of iron and aluminum. Iron-bound P is sensitive to changes in redox-conditions, but part of it was buried in the estuaries, possibly because of high sedimentation rates and incomplete reduction of iron. The open sea sediments in the central and western Gulf of Finland were dominated by apatite-P, which was also abundant in the areas strongly affected by sediment transportation. The burial of sediment P was most effective in the areas rich in apatite-P, which is a relatively stable form of P in sediment. In the eastern Gulf of Finland, organic P forms predominated in the organic-rich sediments. A part of these P forms will be buried, while part will be degraded in the long term, releasing soluble P to the pore water. In the poorly oxygenated areas, iron compounds at the sediment surface are not able to retain P released during mineralisation of organic matter or reduction-induced dissolution of iron-compounds in deep sediment layers. However, in the shallow coastal areas overlain by oxic near-bottom water, the organic-rich surface sediment can also become temporarily reduced and release P from the sediment to the overlaying water. The considerable variation in the chemical composition of sediment P reserves in the northeastern Baltic Sea proved that it is an important factor and should be taken into account when evaluating the release of sediment P and the role of P reserves in bottom sediments in eutrophication.

From the river to the open sea - a critical life phase of young Atlantic salmon migrating from the Simojoki river

Long-term monitoring data collected from wild smolts of Atlantic salmon (Salmo salar) in the Simojoki river, northern Finland, were used in studying the relationships between the smolt size and age, smolt and postsmolt migration, environmental conditions and postsmolt survival. The onset of the smolt run was significantly dependent on the rising water temperature and decreasing discharge of the river in the spring. The mean length of smolts migrating early in the season was commonly higher and the mean age always older than among smolts migrating later. Many of the smolts migrating early in the season and almost all smolts migrating later had started their new growth in spring in the river before their sea entry. Among postsmolts, the time required for emigration from the estuary was dependent on the sea surface temperature (SST) off the river, being significantly shorter in years with warm than cold sea temperatures. After leaving the estuary, the postsmolts migrated southwards along the eastern coast of the northern Gulf of Bothnia, the geographical distribution of the tag recoveries coinciding with the warm thermal zone in spring in the coastal area. After arriving in the southern Gulf of Bothnia in late summer the postsmolts mostly migrated near the western coast, reaching the Baltic Main Basin in late autumn. Until the early 1990s there was only a weak positive association between smolt length and postsmolt survival. However, following a subsequent decrease in the mean smolt size, a significant positive dependence was observed between smolt size and the reported recapture rate of tagged salmon. The differences in recapture rates between smolts tagged during the first and second half of the annual migration season were insignificant, indicating that the seasonal variation in smolt size and age seem to be too small to affect survival. Among the climatic factors examined, the summer SST in the Gulf of Bothnia was most clearly related to the survival of the wild postsmolts. Postsmolt survival appeared to be highest in years when the SST in June in the Bothnian Bay varied between 9 and 12 ºC. In addition, the survival of wild postsmolts showed a significant positive dependence on the SST in July in the Bothnian Sea, but not on the abundance of the prey fish (0+ herring, Clupea harengus and sprat, Sprattus sprattus) in the Bothnian Sea and in the Baltic Main Basin. The results suggest, that if the incidence of extreme weather conditions were to increase due to climatic changes, it would probably reduce the postsmolt survival of wild salmon populations. For improving the performance of hatchery-reared smolts, it could be useful to examine opportunities to produce smolts that are in their smolt traits and abilities more similar to the wild smolts described in this thesis.

Denitrification in the River Estuaries of the Northern Baltic Sea

Estuaries have been suggested to have an important role in reducing the nitrogen load transported to the sea. We measured denitrification rates in six estuaries of the northern Baltic Sea. Four of them were river mouths in the Bothnian Bay (northern Gulf of Bothnia), and two were estuary bays, one in the Archipelago Sea (southern Gulf of Bothnia) and the other in the Gulf of Finland. Denitrification rates in the four river mouths varied between 330 and 905 mu mol N m(-2) d(-1). The estuary bays at the Archipelago Sea and the Gulf of Bothnia had denitrification rates from 90 mu mol N m(-2) d(-1) to 910 mu mol N m(-2) d(-1) and from 230 mu mol N m(-2) d(-1) to 320 mu mol N m(-2) d(-1), respectively. Denitrification removed 3.6-9.0% of the total nitrogen loading in the river mouths and in the estuary bay in the Gulf of Finland, where the residence times were short. In the estuary bay with a long residence time, in the Archipelago Sea, up to 4.5% of nitrate loading and 19% of nitrogen loading were removed before entering the sea. According to our results, the sediments of the fast-flowing rivers and them estuary areas with short residence times have a limited capacity to reduce the nitrogen load to the Baltic Sea.

Anaerobic ammonium oxidation (anammox) in sediments of the Gulf of Finland

Anaerobic ammonium oxidation (anammox) and denitrification were measured in the open sea and coastal accumulation basins of the Gulf of Finland. The different methods used gave conflicting results on the importance of the anammox process in the sediments. Anammox generally contributed less than 20 % to the total N-2 production, and no anammox was found in a shallow inner estuary basin. However, the discovery of the anammox process in the open sea sediments challenges the denitrification measurements made in the area, as the coexistence of anammox and denitrification compromises the central assumptions behind the method used in denitrification measurements and causes overestimates of the N-2 production. The high (NO3-)-N-15 incubation concentration used in Baltic Sea denitrification measurements exacerbates this overestimation, which is likely to have been substantial.