Observations of recovery of the benthic macroinvertebrate community in an acid-impacted upland stream in Ireland

摘要

Acidification occurs in areas of base-poor geology such as granite, where the acid neutralizing capacity (ANC) of stream water is low due to a lack of base cation inputs from geochemical weathering (BOWMAN 1991). Streams with alkalinity values < 12 mg CaCO_3/l (240 μeq/l) have often been termed acid-sensitive (Irish Forestry Service 2002). During periods of heavy rainfall and snowmelt, hydrogen and heavy metal ions (particularly aluminium) may be leached from base-poor soils and drained into surrounding freshwater systems (KIMMELL et al. 1985). With low cation inputs, such leaching results in decreased pH and alkalinity levels and increased aluminium concentrations.