Chemical Analysis of a River

Rivers are dynamic systems that receive minerals and nutrients through sedimentation, rain, surface- and groundwater and human-generated pollution. Chemical analysis of river water can paint a picture of the river's overall water quality and indications of nutrient dynamics in the surrounding landscape.

Common Analyses

• Nutrients such as carbon, nitrogen and phosphorus are commonly analyzed in rivers. Excess nutrients in a river can lead to eutrophication, which may result in algal blooms, thereby stressing other plants and animals in the river by consuming the majority of the dissolved oxygen.

Methods

• There are a variety of ways to analyze water samples, but common instruments are ion chromatographs and spectrophotometers. Ion chromatographs operate based on the size and ionic charge of compounds such as phosphate and nitrate. Spectrophotometers transmit a beam of light at a particular wavelength through the sample and measure the amount of light absorbed.

Nutrient Sources

• As water moves across the surface of a landscape and through the ground, nutrients and minerals can dissolve in the water and get carried into rivers. Agricultural fields are common sources for nitrogen, phosphorus and pesticides. Urban areas can be sources of industrial chemicals, fuel products and heavy metals.

Landscape Effects

• Depending on the size of the river, nutrients and pollutants in the water can be carried great distances to other aquatic systems. The majority of the nitrogen found in the the Gulf of Mexico originates in watershed of the Mississippi River.

Prevention

• The best way to maintain water quality and minimize the spread of nutrients through rivers is to reduce the nutrient input throughout the river's watershed. For example, riparian buffers are patches of vegetation surrounding a river that can intercept excess nutrients and minimize the overall nutrient load to the river system.