Lake and mire isolation data set for the estimation of post-glacial land uplift in Fennoscandia

Postglacial land uplift is a complex process related to the continental ice retreat that took place about 10 000 years ago and thus started the viscoelastic response of the Earth's crust to rebound back to its equilibrium state. To empirically model the land uplift process based on past behaviour of shoreline displacement, data points of known spatial location, elevation and dating are needed. Such data can be obtained by studying the isolation of lakes and mires from the sea. Archaeological data on human settlements (i.e. human remains, fireplaces etc.) are also very useful as the settlements were indeed situated on dry land and were often located close to the coast. This information can be used to validate and update the postglacial land uplift model. In this paper, a collection of data underlying empirical land uplift modelling in Fennoscandia is presented. The data set is available at https://doi.org/10.1594/PANGAEA.905352 (Pohjola et al., 2019).

Lake and mire isolation data set for the estimation of post-glacial land uplift in Fennoscandia

Postglacial land uplift is a complex process related to the continental ice retreat that took place about 10,000 years ago and thus started the viscoelastic response of the Earth's crust to rebound back to it's equilibrium state. To empirically model the land uplift process based on past behavior of shoreline displacement, data points of known spatial location, elevation and dating are needed. Such data can be obtained by studying the isolation of lakes and mires from the sea. Archaeological data on human settlements (i.e., human remains, fireplaces etc.) are also very useful as the settlements were indeed situated on dry land and were often located close to the coast. This information can be used to validate and update the postglacial land uplift model. In this paper, a collection of data underlying empirical land uplift modeling in Fennoscandia is presented. The data set is available at https://doi.org/10.1594/PANGAEA.905352 (Pohjola et al. 2019).

A historical review of gravimetric observations in Norway

The first gravity determinations in Norway were made by Edward Sabine in 1823 with a pendulum instrument by Henry Kater. Seventy years later a Sterneck pendulum was acquired by the Norwegian Commission for the International Arc Measurements. It improved the precision and eventually reduced the bias of the absolute calibration from 85 to 15 mGal. The last pendulum observations in Norway were made in 1955 with an instrument from Cambridge University. At a precision of ±1 mGal, the purpose was to calibrate a section of the gravity line from Rome, Italy, to Hammerfest, Norway. Relative spring gravimeters were introduced in Norway in 1946 and were used to densify and expand the national gravity network. These data were used to produce regional geoids for Norway and adjacent ocean areas. Improved instrument precision allowed them to connect Norwegian and foreign fundamental stations as well. Extensive geophysical prospecting was made, as in other countries. The introduction of absolute gravimeters based on free-fall methods, especially after 2004, improved the calibration by 3 orders of magnitude and immediately revealed the secular changes of the gravity field in Norway. This was later confirmed by satellite gravimetry, which provides homogeneous data sets for global and regional gravity models. The first-ever determinations of gravity at sea were made by pendulum observations onboard the Norwegian polar vessel Fram during frozen-in conditions in the Arctic Ocean in 1893–1896. Simultaneously, an indirect method was developed at the University of Oslo for deducing gravity at sea with a hypsometer. The precision of both methods was greatly superseded by relative spring gravimeters 50 years later. They were employed extensively both at sea and on land. When GPS allowed precise positioning, relative gravimeters were mounted in airplanes to cover large areas of ocean faster than before. Gravimetry is currently being applied to study geodynamical phenomena relevant to climate change. The viscoelastic postglacial land uplift of Fennoscandia has been detected by terrestrial gravity time series as well as by satellite gravimetry. Corrections for local effects of snow load, hydrology, and ocean loading at coastal stations have been improved. The elastic adjustment of present-day melting of glaciers at Svalbard and in mainland Norway has been detected. Gravimetry is extensively employed at offshore oil facilities to monitor the subsidence of the ocean floor during oil and gas extraction.

Urban impact on water bodies in the Luleå area, northern Sweden, and the role of redox processes

Sediment and water from urban water bodies in the Luleå area, northern Sweden, were studied to determine the degree of contamination from metals and PAHs (polycyclic aromatic hydrocarbons). The heavy metals Cd, Cu, Pb and Zn, which are of main concern in urban stormwater, are enriched in all investigated bays. PAH concentrations were also found to be enriched. The water and sediment quality of the investigated water bodies depends on catchment area characteristics and emission impact, from point sources in particular. Water volume and turnover rate in the water bodies with low water levels and no surface runoff during wintertime, and ice covering during winter, contribute to anoxic conditions in the water column and sediments. The present redox conditions in the water bodies predominantly cause fixation of pollutants in the sediment due to formation of sulphides and slow oxidation of organic pollutants. Postglacial land uplift implies continuous changes in the environment, which can lead to changing redox conditions, thereby necessitating new risk assessments.

Postglacial Land Uplift and the Autonomous Åland Islands as a Demilitarized Zone

The impact of postglacial land uplift on the geographical extent of the demilitarized zone of the autonomous Åland Islands is discussed. Ambiguities and inconsistencies in the Åland Convention, on the order of nautical miles, are revealed; they are due not only to the land uplift itself, but also to unclear definitions of coordinates. Further complications are caused by disagreements between the autonomy boundary and the demilitarization boundary. Suggestions for solving the problems are given, including minor amendments and clarifications of the Åland Convention, and also a minor amendment of the Autonomy Constitution of Åland.