title: The influence of organic acids in relation to acid deposition in controlling the acidity of soil and stream waters on a seasonal basis.
abstract: Much uncertainty still exists regarding the relative importance of organic acids in relation to acid deposition in controlling the acidity of soil and surface waters. This paper contributes to this debate by presenting analysis of seasonal variations in atmospheric deposition, soil solution and stream water chemistry for two UK headwater catchments with contrasting soils. Acid neutralising capacity (ANC), dissolved organic carbon (DOC) concentrations and the Na:Cl ratio of soil and stream waters displayed strong seasonal patterns with little seasonal variation observed in soil water pH. These patterns, plus the strong relationships between ANC, Cl and DOC, suggest that cation exchange and seasonal changes in the production of DOC and seasalt deposition are driving a shift in the proportion of acidity attributable to strong acid anions, from atmospheric deposition, during winter to predominantly organic acids in summer.
authors.affiliation: Earth and Biosphere Institute, School of Geography, University of Leeds, Leeds LS2 9JT, UK. p.j.chapman@leeds.ac.uk
authors.forename: Pippa J
authors.initials: PJ
authors.lastname: Chapman
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Clark
authors.forename: Brian
authors.initials: B
authors.lastname: Reynolds
authors.forename: John K
authors.initials: JK
authors.lastname: Adamson
mesh_terms: D015258:Acid Rain; D000143:Acids / Q000032:analysis*; D000838:Anions; D002412:Cations; D004739:England; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis*; D005618:Fresh Water; D006863:Hydrogen-Ion Concentration; D009930:Organic Chemicals / Q000032:analysis*; D045483:Rivers; D012621:Seasons; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis; D012995:Solubility; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D015258:Acid Rain; D000143:Acids; D000838:Anions; D002412:Cations; D004785:Environmental Pollutants; D009930:Organic Chemicals; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical