title: Pre-industrial atmospheric pollution: was it important for the pH of acid-sensitive Swedish lakes?
abstract: Acid rain has caused extensive surface water acidification in Sweden since the mid-20th century. Sulfur emissions from fossil-fuel burning and metal production were the main sources of acid deposition. In the public consciousness, acid deposition is strongly associated with the industrial period, in particular the last 50 years. However, studies of lake-water pH development and atmospheric pollution, based on analyses of lake sediment deposits, have shown the importance of a long-term perspective. Here, we present a conceptual argument, using the sediment record, that large-scale atmospheric acid deposition has impacted the environment since at least Medieval times. Sulfur sources were the pre-industrial mining and metal industries that produced silver, lead and other metals from sulfide ores. This early excess sulfur deposition in southern Sweden did not cause surface water acidification; on the contrary, it contributed to alkalization, i.e. increased pH and productivity of the lakes. Suggested mechanisms are that the excess sulfur caused enhanced cation exchange in catchment soils, and that it altered iron-phosphorus cycling in the lakes, which released phosphorus and increased lake productivity.
authors.affiliation: Department of Ecology and Environmental Sciences, Umeå University, SE-901 87 Umeå, Sweden. Richard.Bindler@eg.umu.se
authors.forename: Richard
authors.initials: R
authors.lastname: Bindler
authors.forename: Tom
authors.initials: T
authors.lastname: Korsman
authors.forename: Ingemar
authors.initials: I
authors.lastname: Renberg
authors.forename: Peter
authors.initials: P
authors.lastname: Högberg
mesh_terms: D015258:Acid Rain; D000393:Air Pollutants / Q000266:history*; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry; D049668:History, 15th Century; D049669:History, 16th Century; D049670:History, 17th Century; D049671:History, 18th Century; D049672:History, 19th Century; D049673:History, 20th Century; D049690:History, Ancient; D049691:History, Medieval; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000032:analysis / Q000266:history; D010758:Phosphorus / Q000032:analysis; D013440:Sulfides / Q000032:analysis; D013548:Sweden
chemical_list: D015258:Acid Rain; D000393:Air Pollutants; D013440:Sulfides; D010758:Phosphorus; D007854:Lead