Svavelflöden

Svavelflöden, or "sulfur flow," is a term used in Swedish geology to describe streams or river sections where sulfur compounds are unusually abundant in the water, sediments, or precipitates. The term captures natural or anthropogenic systems in which sulfur is mobilized and discharged with the liquid phase, often imparting distinctive chemistry and color to the water.

Formation and chemistry: Svavelflöden form where groundwater, surface water, or wastewater interacts with sulfide minerals or volcanic/hydrothermal sources. Oxidation of sulfide minerals releases sulfur species such as hydrogen sulfide (H2S) and sulfates, while reduction processes can maintain dissolved sulfide in the water. The water is often acidic, with distinctive odors and deposits of elemental sulfur or iron sulfides. In some cases, acidic mine drainage can create svavelflöden downstream of ore deposits.

Ecology: Microbial communities play a key role, including sulfur-oxidizing bacteria that derive energy from oxidizing reduced sulfur compounds. These organisms can form biofilms or mats that color the water and sediments and influence the local sulfur cycle. The conditions in svavelflöden are typically extreme, with low pH and low to moderate dissolved oxygen.

Distribution and significance: The term is used in scientific literature and field guides for regions with sulfur-rich waters, including geothermal, volcanic, and mining landscapes. Studying svavelflöden helps illuminate biogeochemical sulfur cycling, mineral deposition, and the ecological impact of sulfur-rich discharges. They may also be of interest to geotourism and environmental monitoring.

See also: sulfur cycle, sulfur-oxidizing bacteria, acid mine drainage, hydrothermal vent, geothermal spring.