Baseline Acidity of Ancient Precipitation from the South Pole

• Main Authors: Cragin,J H, Giovinetto,M B, Gow,A J
• Other Authors: COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
• Format: Text
• Language: English
• Published: 1984
• Subjects: Meteorology; Geology; Geochemistry and Mineralogy; Snow; Ice and Permafrost; *ICE; *PH FACTOR; CHEMICAL ANALYSIS; ANTARCTIC REGIONS; CORE SAMPLING; ICE CAPS; *Acid precipitation; *Ancient precipitation; Antarctic; South Pole; Antarc*; Ice; permafrost; South pole
• Online Access: http://www.dtic.mil/docs/citations/ADA145007; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA145007

Measurements of meltwater pH from annual layers of South Pole firn and ice samples ranging in age from 40 to 2000 years B.P. show that precipitation at this remote site has a higher natural acidity than that expected from atmospheric equilibrium with CO2. The average pH of deaerated (CO2-free) samples was 5.64 + or - 0.08, while air-equilibrated samples averaged 5.37 + or - 0.008, a pH that is about a factor of two more acidic than the expected background pH of 5.65. The observed 'excess' acidity can be accounted for by natural SO4(2)- and NO(3)- levels in the samples probably originating from non-anthropogenic H2SO4 and HNO3. Because of the presence of these naturally occurring acids in South Pole precipitation, a pH of 5.4 is considered a more representative baseline reference pH for acid precipitation studies.