Watershed's size has a huge role in River Networks' ability to remove pollutants

Watershed's size has a huge role in River Networks' ability to remove pollutants ...

The planets river networks are in a very real sense similar conduits that aid in keeping the planet alive.

One of a rivers'' vital tasks is eliminating some of the pollution that is trapped in its waters by roads, lawns, septic systems, and wastewater treatment facilities, agriculture, and others, before they reach sensitive downstream ecosystems like estuaries and oceans.

New research has found that watershed size plays a significant role in a river networks'' ability to do this work. Both tests further our understanding of which estuaries and coastal areas will be more affected by human development in their watersheds, and further investigate the implications of the global carbon cycle.

A team of scientists investigated how the area of land (the watershed) that drains into an aquatic system increases, and how rivers filter pollution increases at a linear rate, and increases even faster thanks to larger rivers that go hand-in-hand.

According toWilfred Wollheim, a researcher on natural resources and the environment, and the principal author of thearticle, body size increases and the amount of energy it needs to do its work (metabolism) increases. However, for body metabolism, it is well known that as body size increases, the metabolism decreases at a slower rate. We wanted to see if something similar happened to aquatic metabolism or as we discovered something new.

Wollheim and his team describe what they learned about watershed size and river function as superlinear scaling, and he claims it happens because larger rivers contribute disproportionately to the pollution-filtering function of all aquatic ecosystems, including lakes, streams, rivers, and wetlands.

According to Wollheim, research suggests that land use and mitigate non-point source pollution, such as runoff carrying fertilizers, herbicides, insecticides, and toxic chemicals, are essential to reduce non-point pollution in larger watersheds, which are less capable to filter pollutants than larger watersheds. It is also important to mitigate non-point pollution in areas of the watershed that are closer to an estuary or coastal area, where the system will have fewer chances to filter pollutants before it reaches those critical areas.

The research also reveals new information about the role of rivers in the global carbon cycle.

Watersheds in larger watersheds could release carbon that is being transferred back to the atmosphere due to superlinear scaling, although this is not the case in smaller watersheds.

This new information about aquatic ecosystems and rivers in particular will assist stakeholders in developing better pollution management strategies and improve our understanding of the feedback loop between the Earths ecosystems and its atmosphere, as well as how it affects climate fluctuations.

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