Precipitation, snowpack, stream-water ion chemistry, and flux in a northern Michigan watershed, 1982-1991

• Published in: Canadian journal of fisheries and aquatic sciences 1996-12, Vol.53 (12), p.2659-2672
• Main Authors: Stottlemyer, J R, Toczydlowski, D
• Format: Article
• Language: English
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; Freshwater; Geochemistry; Hydrology; Hydrology. Hydrogeology; Mineralogy; Silicates; Water geochemistry
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/f96-236

Samples of precipitation, snowpack and stream water were collected weekly between 1982 and 1991 from 4 stations in the Calumet catchment adjacent to Superior lake and analysed using ion chromatography. Stream water discharge was measured continuously. Data were analysed using SYSTAT models and trends are presented. Annual precipitation, hydrogen ion and sulphate inputs decreased during the study period. Sulphate in precipitation decreased, mostly during winter months. Winter precipitation and ammonium, hydrogen ion, nitrate and sulphate inputs decreased. Mid-winter snowmelt was attributed to unfrozen soil and intermittent thaws. Approximately 90 per cent of snowmelt entered unfrozen soil which changed its chemistry. More than 99 per cent of snowmelt hydrogen ions and 80 per cent of nitrate ions were retained by the watershed. The acid neutralization capacity of stream water at times of peak snowmelt declined by 360 ueq per litre of which more than 90 per cent was attributed to dilution. During snowmelt, nitrate and sulphate in streamwater decreased by more than 85 per cent and by less than 10 per cent, respectively. Buffering of sulphate concentrations in stream water was ascribed to desorption of sulphate from soil. There are 68 references.