Seasonal Variation in Selected Nutrients of a River System

Abstract

Water samples were collected biweekly from five locations on the Grand River, Ont., from August 16, 1967, to September 1, 1968. Headwater nutrient levels and associated water chemistry were radically altered by the influence of a small city. Processes of recovery occurred downriver in a primarily agricultural watershed. Levels of dissolved oxygen, carbon dioxide, pH, alkalinity, hardness, ammonia, nitrate, and silica followed similar seasonal patterns at all locations. High and widely fluctuating levels of chloride, ammonia, nitrate-N, nitrite, and orthophosphate were evidence of gross enrichment. Nitrate-N, orthophosphate, iron, and sulfate levels varied irregularly during the 13-month period.