title: Groundtruthing and potential for predicting acid deposition impacts in headwater streams using bedrock geology, GIS, angling, and stream chemistry.
abstract: Atmospheric acid deposition is of environmental concern worldwide, and the determination of impacts in remote areas can be problematic. Rainwater in central Pennsylvania, USA, has a mean pH of approximately 4.4. Bedrock varies dramatically in its ability to neutralize acidity. A GIS database simplified reconnaissance of non-carbonate bedrock streams in the Valley and Ridge Province and identified potentially chronically impacted headwater streams, which were sampled for chemistry and brook trout. Stream sites (n=26) that originate in and flow through the Tuscarora had a median pH of 5.0 that was significantly different from other formations. Shawangunk streams (n=6) and non-Tuscarora streams (n=20) had a median pH of 6.0 and 6.3, respectively. Mean alkalinity for non-Tuscarora streams (2.6 mg/L CaCO(3)) was higher than the mean for Tuscarora streams (0.5 mg/L). Lower pH and alkalinity suggest that the buffering capability of the Tuscarora is inferior to that of adjacent sandstones. Dissolved aluminum concentrations were much higher for Tuscarora streams (0.2 mg/L; approximately the lethal limit for brook trout) than for non-Tuscarora streams (0.03 mg/L) or Shawangunk streams (0.02 mg/L). Hook-and-line methods determined the presence/absence of brook trout in 47 stream reaches with suitable habitat. Brook trout were observed in 21 of 22 non-Tuscarora streams, all 6 Shawangunk streams, and only 9 of 28 Tuscarora stream sites. Carefully-designed hook-and-line sampling can determine the presence or absence of brook trout and help confirm biological impacts of acid deposition. 15% of 334 km of Tuscarora stream lengths are listed as "impaired" due to atmospheric deposition by the Pennsylvania Department of Environmental Protection. 65% of the 101 km of Tuscarora stream lengths examined in this study were impaired.
authors.affiliation: Department of Geology, Bucknell University, Lewisburg, PA 17837, USA. kirby@bucknell.edu
authors.forename: C S
authors.initials: CS
authors.lastname: Kirby
authors.forename: B
authors.initials: B
authors.lastname: McInerney
authors.forename: M D
authors.initials: MD
authors.lastname: Turner
mesh_terms: D015258:Acid Rain; D000535:Aluminum / Q000032:analysis; D000818:Animals; D004784:Environmental Monitoring; D005544:Forecasting; D040362:Geographic Information Systems; D055593:Geological Phenomena; D005844:Geology; D006863:Hydrogen-Ion Concentration; D010414:Pennsylvania; D045483:Rivers / Q000737:chemistry*; D014337:Trout
chemical_list: D015258:Acid Rain; D000535:Aluminum