Runo Löfvendahl

CHEMISTRY OF SUSPENDED PARTICLES IN THE SOUTHERN BALTIC SEA

Dissolved and suspended concentrations of Al, Ba, Fe, Mn, and Si and suspended P and Ti have been studied in the Baltic proper, the Belt Sea-Kattegat and the Aland Sea. Approximately 20% of total A ...

Strontium in rivers of the Baltic Basin

The rivers in the Baltic Basin drain a mixture of bedrocks ranging from Mesozoic-Paleozoic sediments in the south to Proterozoic-Archean intrusives in the north. The rivers in the sedimentary basin in the south have high concentrations of Sr, in the interval 100–500 µg l−1 while the87Sr/86Sr ratio is close to that of seawater, i.e. 0.71. The northern rivers in the Precambrian shield area on the other hand have low Sr concentrations of 15–50 µg l−1 with high87Sr/86Sr ratios of about to 0.73 (0.721–0.745). The riverine input of dissolved Sr to the brackish Baltic Sea approaches 60 tons year−1, with a weighted mean concentration approaching 130 µg l−1 and a weighted mean87Sr/86Sr ratio close to 0.712. Although the sedimentary area in the south supplies only about 43% of the total river discharge, it gives about 88% of the total Sr input. Because of this and the strong regional riverine variation in87Sr/86Sr ratio, Sr and its isotopes seem to be a convenient tool to unveil mixing relations of water masses in the northern Baltic Sea, provided high resolution analyses are applied. For an overall characterization of water mixing in the Baltic Sea, the Nd system will be superior to that of Sr.

Major element chemistry, δ2H, δ18O and 87Sr/86Sr in a snow profile across central Scandinavia

Abstract In late February 1988, fresh snow was sampled at eight stations along a 450 km long transect, spanning the Scandinavian Peninsula from the Atlantic Ocean in the west to the Gulf of Bothnia in the east. The elements Na, Mg, Ca, S, Cl, Sr, Al, Fe, Mn and Zn were analyzed, and the nuclide pairs 87 Sr 86 Sr, 18 O 16 O and 2 H 1 H measured. The concentrations of Na, Mg, Cl and Sr decrease rapidly with distance from the Atlantic coast. The other elements studied reflect more complicated patterns, caused by addition of terrigeneous matter and anthropogenic pollution. Stable oxygen and hydrogen isotopic compositions follow the general precipitation pattern, with values close to seawater in the west, becoming isotopically progressively lighter eastwards. The 87 Sr/ 86 Sr ratio in snow varies from 0.7098 near the Atlantic Ocean to 0.7194 at the easternmost station. Mixing calculations reveal that seawater contributes about 90% of the Sr at the westernmost stations, decreasing to 10–30% some 300 km eastwards. The increase in the 87 Sr/ 86 Sr ratio inland is controlled by Sr fractions more radiogenic than seawater, but strongly heterogeneous. The easternmost station is distinctly influenced by pollution, giving enhanched concentrations of S, Ca and Sr and the highest 87 Sr/ 86 Sr ratio.

Dissolved uranium in the Baltic Sea

Filtered water from the Baltic Sea was analysed for uranium concentration and 234U/238U activity ratio with alpha-ray spectrometry. The uranium concentration shows a strong correlation to salinity, the correlation coefficient being close to 0.98. Consequently, the uranium concentration increases from 0.15 μg kg−1 in the northern part, dominated by fresh water, to above 1.0 μg kg−1 in the Belt Sea. However, the data also show that dissolved uranium is not strictly conservative in the Baltic. In deeper intermittently anoxic basins of the Baltic Proper, the element is removed from the water phase and incorporated into the sediment. This is most evident in the Gotland Deep, which has been anoxic below 200 m depth since 1979.

The Götemar granite — isotopic and geochemical evidence for a complex history of an anorogenic granite

Abstract The Gotemar massif, located in south-eastern Sweden, consists mainly of a coarse-grained homogeneous alkali feldspar granite with subordinate fine-grained varieties. A multi-radiometric dating approach gives a variety of discordant data depending on method and material. The coarse-grained Gotemar granite is believed to have intruded and crystallized between 1400 and 1350 Ma ago. The isotopic data, together with Ti, Zr, Y and Nb ratios, strongly resemble those of the Jungfrun granite which represents another anorogenic intrusion in the area. This suggests a common origin for these two granites. Rb-Sr dating of the fine-grained aplitic varieties of the Gotemar granite gives an age of 1255 Ma. It is not clear whether these represent late differentiates, or if their age is lowered by late-stage hydrothermal activity.

Radiometric dating of the Jungfrun granite

Abstract The Jungfrun massif consists of a homogeneous alkali-feldspar granite with scattered light aplitic inclusions of unknown genesis. Dating of the Jungfrun massif shows an inconsistent pattern when comparing the K-Ar, Rb-Sr and U-Pb systems. A Rb-Sr whole-rock isochron age of 1386 ± 21 Ma is accepted as representing the time of intrusion while a U-Pb discordia age of 1480+10 -31 Ma on zircons is dismissed as erroneous. The reason for this is presence of cores in the zircons. A K-Ar age of 1412 ± 20 Ma on biotite points to excess Ar, probably inherited from a former country rock. The small anorogenic massifs of Jungfrun and the related Gotemar granite are not unique as earlier assumed. In southeastern Baltoscandia other anorogenic granites formed 1400 ± 50 Ma ago are found. These granitoids, collectively known as the Karlshamn group, show a progressive evolution from calc-alkaline character towards somewhat more alkaline types with time. The latter seem to be related with the Jungfrun-Gotemar alkali-...

Radioactive disequilibria and apparent ages of secondary uranium minerals from Sweden

Abstract Thorium and uranium nuclides have been measured using high-resolution alpha spectrometry in order to examine the potential of secondary uranium minerals for disequilibrium dating purposes. Mineral ages are proportional to the distance below the bedrock surface. Minerals coated on the bedrock surface are usually postglacial with apparent ages below 10 000 years. Minerals collected from cracks and fissures 3–100 mm below the bedrock surface give apparent ages from 14 000 years to equilibrium ages of more than 300 000 years. Samples from drill-cores collected more than one metre below the surface approach equilibrium. Some mineral samples have lost uranium, indicating open system conditions. The examined material does not allow the establishment of a definite relationship between glaciation and mineral ages.

Environmental monitoring with river suspended matter: case study in the River Dalälven, central Sweden

Abstract Heavy metal concentrations are presented for suspended sediment from the River Dalalven, central Sweden. The river is contaminated by acid mine drainage and data from the most polluted tributary, Garpenbergsan, are also presented. Element/Al ratios in the suspended phase showed that K, Mg and Ti were mainly hosted in detrital particles together with a large fraction of Si. Between 50 and 60% of the load of Fe, Ca and Na were in non-detrital form. Less than 10% of the total load of suspended Mn and P were in a detrital form. The sediment in the River Dalalven is polluted by As, Cr, Cu, Hg, Ni, Pb and Zn. These elements, except Pb, showed an even stronger enrichment in the suspended phase. This indicated that between one third and one half of the suspended load was recirculated to the water column during sedimentation. Arsenic, Cr, Cu, Hg, Ni, Pb and Zn showed linear correlations with non-detrital Fe, close to the inflow of the polluted stream Garpenbergsan. Deposition of non-detrital Fe, Na, Cr, Cu and Ni in the sedimentation basins close to the river mouth reduced the suspended discharge of these elements to the Baltic Sea. However, the basins acted as sources for non-detrital suspended As, Hg, Pb and Zn during the studied period. The calculated net export, in a non-detrital form, for these elements was 141, 3.7,1100 and 7000 kg, respectively, as measured between May and October.

An isotope study of Swedish secondary U—Pb minerals

Abstract Lead isotope composition of the secondary uranium minerals kasolite and wolsendorfite has been examined in a masspectrometer. The material originates from uranium mineralizations, radioactive pegmatites and a site with no known primary uranium mineral source. The lead of the secondaries consists of varying proportions of common lead (rock lead) and radiogenic lead formed by decay of uranium and thorium. Uranogenic lead dominates in all but one of the samples examined. The mineralization age is approximated by examining secondary uranium minerals. The secondaries are usually depleted in uranium in relation to lead, but the reverse relation also exists. The examined minerals, with one possible exception, seem to have been formed within recent geological time.

Weathering of runestones in a millennian perspective

Publisher Summary Runic monuments are Scandinavian specialty and can be divided into three groups: ancient runestones, Viking runestones from 11th century, and medieval runic monuments from 12th century and later. The chapter discusses the chronological century-long studies of stone weathering to define the total deterioration. This chapter focuses on the Viking age monuments, because they are the numerous and consist of erected, standing stones. The monuments were altered by weathering of chemical, biological, and physical nature. Through the centuries, the chemical and biological weathering alters the surface by increasing the porosity after the dissolution of more easily weathered minerals such as calcite, biotite, and anorthitic plagioclase (calcium-rich feldspar). This facilitates material loss by physical processes such as freeze/thaw cycles and salt crystallization/dissolution. Thus, the weathering increases strongly with time. Different bedrock types show different weathering rates. Isotropic siliceous rocks such as granite are more resistant, while anisotropic rocks such as limestone and sandstone degrades more rapidly. This pattern is illustrated in the examination of 22 different runic monuments in Sweden. Many factors tend to disguise this general pattern, the most important being human interference.