The Zeeman effect for weak magnetic fields

The polarization of a normal Zeeman triplet is discussed for the case in which the lifetime of the excited state of the atom is comparable to or shorter than the period of Larmor precession.     

Alteration paragenesis and mineral chemistry of the Tjårrojåkka apatite–iron and Cu (-Au) occurrences, Kiruna area, northern Sweden

The northern Norrbotten area in northern Sweden, is an important mining district and hosts several deposits of Fe-oxide Cu-Au-type. One of the best examples of spatially, and possibly genetically, related apatite–iron and copper–gold deposits in the region is at Tjårrojåkka, 50 km WSW of Kiruna. The deposits are hosted by strongly sheared and metamorphosed intermediate volcanic rocks and dolerites and show a structural control. The Tjårrojåkka iron deposit is a typical apatite–iron ore of Kiruna-type and the Tjårrojåkka copper occurrence shows the same characteristics as most other epigenetic deposits in Norrbotten. The host rock has been affected by strong albite and K-feldspar alteration related to mineralisation, resulting in an enrichment of Na, K, and Ba. Fe and V were depleted in the altered zones and added in mineralised samples. REE were enriched in the system, with the greatest addition related to mineralisation. Y was also mobile associated with albite alteration and copper mineralisation. The Tjårrojåkka iron and copper deposits show comparable hydrothermal alteration minerals and paragenesis, which might be a product of common host rock and similarities in ore fluid composition, or overprinting by successive alteration stages. Mineralogy and mineral chemistry of the alteration minerals (apatite, scapolite, feldspars, amphiboles, and biotite) indicate a higher salinity and Ba/K ratio in the fluid related to the alterations in the apatite–iron occurrence than in the copper deposit, where the minerals are enriched in F and S. The presence of hematite, barite, and in SO₄ in scapolite suggests more oxidising-rich conditions during the emplacement of the Tjårrojåkka-Cu deposit. From existing data it might be suggested that one evolving system created the two occurrences, with the copper mineralisation representing a slightly later product.     

The acute toxicity of motor fuels to brackish water organisms

The addition of synthetic additives, such as methanol and methyl tertiary butyl ether (MTBE) to the base fuel, with the aim of raising the octane content of motor fuel, is currently of special interest in Sweden. A question, which has to be solved, is whether it is preferable to carry the additives by ship in separate tanks, because of the probable enhanced toxicity of the motor fuels by the addition of solvents, or not. The acute toxicity of these blend fuels has been compared with the acute toxicity of base fuel, gasoline and low leaded gasoline. As test organisms, two representative species of the Baltic Sea have been used, the harpacticoid Nitocra spinipes and the bleak, Alburnus alburnus. The results of the tests show that the acute toxicity of base fuel to aquatic organisms is not increased by the addition of 15% methanol or 5% MTBE.