Stronger Storms Hamper Ability of Streams and Rivers to Clean Up Pollution

Freshwater streams and rivers naturally clean up some forms of pollution originating from urban and agricultural areas, but increased storm intensity reduces this ability, which underscores the need to improve the management of nonpoint sources of pollution and storm water management.

This was found in a new research published in  Water Resources Research , a journal of the American Geophysical Union.   

The research findings advance efforts to further understand the ability of streams and rivers to clean watershed pollution and determine how to best manage nonpoint nitrogen inputs associated with human activity.

Scientists used a new generation of high-technology sensors placed directly into streams and rivers to measure nitrate concentrations continuously under different flow conditions. These sensors are transforming the understanding of water quality and how to improve its management.

Nonpoint source pollution generally results from land runoff, atmospheric deposition, fertilizers, septic systems and/or hydrologic modification from ever expanding road networks. Nonpoint source pollution comes from many diffuse sources such as agricultural land, construction sites, faulty septic systems and residential areas.

It is caused by rainfall or snowmelt moving over and through the ground. As the runoff moves, it picks up and carries away natural elements and human-made pollutants, finally depositing them into streams, rivers, lakes, wetlands, coastal waters and ground waters.

Specifically, the researchers found:

1. Urban and agricultural areas contribute much higher nutrient inputs to streams and rivers than forests, especially during storms.
2. Freshwater ecosystems are able to clean some of this higher nutrient input before it gets to coastal areas.
3. The ability of freshwaters to clean up nutrient pollution goes down rapidly with larger storms. Thus, as storminess increases, more nitrate will transfer to coastal areas.
4. Improvements need to be made in nonpoint nutrient management on land by reducing inputs while taking into account different storm intensity or by increased storm water management. This is especially true if climate extremes continue to worsen. 

By Lori Wright 
Read full article at AGU Blogosphere 
Research paper source:  Aquatic Nitrate Retention at River Network Scales across Flow Conditions Determined Using Nested In Situ Sensors, AGU Publications

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• Water Pollution
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