Suo - Mires and peat vol. 27 no. 2 | 1976

The first part of the study is concerned with some general aspects of the various stages of the Baltic Sea, land uplift and shore-line displacement during the period following the last glacial period. Land uplift was much faster immediately after the end of the glacial period than it is today. As a result of land uplift, regressive shoreline displacement, i.e. movement of the shore-line seawards, has prevailed along the coast of Finland during the time following the glacial period. However, in SE Finland the sea has risen during two separate periods, at a faster rate than the rate of land emergence, and so land which has earlier emerged from the sea has again been covered, i.e. transgression has taken place. The Ancylus transgression occured around 9500—9000 B.P. and was caused by the damming up of the water in the Baltic Sea basin at a level above that of the sea during the Ancylus Lake stage. Towards the end of the Ancylus Lake stage rapid regression took place as the surface of the lake subsided to the level of the Atlantic Ocean. Regression changed to transgression after the surface of the ocean had risen, due to the so-called eustatic rise, above the threshold level of the Straits of Denmark. The eustatic rise caused by melting of the glaciers produced a considerable amount of transgression in the Baltic Sea basin during the warm period which started in the Mastogloia stage and continued into the first half of the Litorina Sea stage. At the start of the Litorina Sea stage, between 7500—7000 B.P., the water in the Baltic Sea basin clearly became salty brackish water. The transgression which occured during the Litorina Sea stage extended from the coast of SW Finland as far as the Helsinki—Espoo area. Further west, however, land uplift occured at such a fast rate that shore-line movement throughout the warm period was regressive. In the latter half of the paper, a number of examples have been presented to show, how the various phenomena connected with the development phases of the Baltic Sea and shore-line movement can be seen in the peatland and lake-sediment layers. Examples of peat layers showing transgression are to be found in Hangassuo swamp, near Anjalankoski (Eronen 1976) and Bastuberg swamp, near Porvoo (Eronen 1974). The peat layer covered by the Ancylus transgression is visible in the peat profile from the former swamp. On the other hand, the sediment layer of a small lake is covered by the Litorina transgression in the Bastuberg swamp. In addition to these, a number of examples have been presented of transgression sediment layers produced by the large lakes of the Finnish Lake District. After contracting from the Baltic Sea basin, the water in the Finnish Lake District flowed towards the Gulf of Bothnia. However tilting of the lake basins caused by land uplift of varying degree resulted in transgression, especially in the southern and south-eastern parts of large lakes. Transgression of Lake Päijänne can be seen in layer series from Lahnalampi (Asikkala) (Saarnisto 1971). Transgression of Lake Saimaa has been demonstrated in bottom layer sediments from Puntusensuo (Kerimäki) (Saarnisto 1970). Transgression ceased in both of these large lakes after a new discharge channel had formed. The water from Lake Päijänne started to flow southwards in about 6000 B.P. and the water from Lake Saimaa broke through Salpausselkä II in about 5000 B.P. forming River Vuoksi.

• Eronen, Sähköposti: ei.tietoa@nn.oo

This investigation deals with the peat types, their degree of humification, acidity, water and ash contents, phosphorous, sul-fide and nitrate contents of three peat bogs Hangasneva, Puurokeidas and Suomikeidas situated in North-Satakunta, western Finland. The Sphagnum peats of Puurokeidas bog and Suomikeidas bog are less humified and have lower pH-values than the peats at Hangasneva (Tables 1—2) which contain a higher proportion of Carex residues. The ash contents of Hangasneva peats are greater than those of other bogs. The phosphorus, sulfide and nitrate contents are low. This is very typical of bogs occuring in areas where the bedrock is granite. The history of development of the investigated peat bogs has determined by pollen analysis datings. Peat accumulation started at the time of the boreal age.

• Terho, Sähköposti: ei.tietoa@nn.oo

Different kinds of waste waters can be purified by peat. The right choice of peat quality and its correct handling may be the qualification for reaching the optimum result, i.e. the use of one and the same peat quality for all kinds of purification purposes is not possible. In the present paper, the subject is confined to discussing removal of heavy metals and oils from waste waters, as we have advanced the furthest in these fields and also because peat applies most economically to the purification of relatively small and special flows of waste water. Compared with other sorbents and adsorbents, one of the greatest advantages of peat is its price per removed impurity. At the University of Sherbrooke in Canada, a process has been developed for the removal of heavy metal ions. In this process metal ions are removed in a 2 mm thick continuously moving peat filter. Prior to this phase, the pH of waste water has been changed or sodium sulphide has been added to it. By means of this test equipment, waste waters containing mercury, copper, zinc, iron and chromium have been purified, the removal percentage being from 98 to 99 %. Five units of this process have already been sold. In an investigation carried out at the Technical Research Centre of Finland, the influence of a number of variables, such as particle size, bed thickness, bed density, heat treatment, peat quality, emulsion stability, on the purification degree, oil-binding capacity, headloss and changes in the bed have been investigated. A 98 % removal was reached by means of a 0.05 ... 0.2 m thick peat bed depending on other process parameters, and the oil-binding capacity has been from 0.1 to 0.2 l oil/l peat (corresponding to about 1 ... 2 kg oil/kg peat). An initial difficulty caused by the shrinkage of the bed has been reduced by choosing a better peat quality and optimum conditions. In a peat filtering process either equipment with a fixed bed or continuously running equipment can be used. A modification of the last-mentioned piece of equipment is being developed at the Technical Research Centre of Finland. Cost estimates indicate that a peat filter is favourable alternative in many cases. Furthermore, there are cases where the purification possibility in general is concerned, e.g. many pollution cases, rather than the economical aspects. Provided the production of filtering peat can be started by some enterpriser, there is every probability that even equipment manufacturers will be found.

• Asplund, Sähköposti: ei.tietoa@nn.oo