Water Quality - 8 of 27
Water Quality FAQs - 27 Found
A basic introduction to natural filtering of water can be found on-line at the USGS 'Water Science for Schools' website. The address for the site's ground-water-quality page is:
Natural filtering is a big topic. Some filtering takes place when water flows over the ground, such as when muddy water from a plowed field or a construction site flows through grass or weeds on its way to a stream. Some of the mud is filtered out. In addition, some filtering takes place when the water is in lakes or streams, through the actions of plants and bottom-dwelling animals (like freshwater clams and mussels) that take in water, remove nutrients, and put it out again. Here's a page that talks about filtering in wetlands:
Here's another, longer, but very good piece about wetlands. The part about natural filtering is in the section called 'maintenance of water quality':
Wetland Hydrology, Water Quality, and Associated Functions
A lot of filtering takes place in the uppermost layer of sediment at the bottom of a lake or stream. This is called the hyporheic zone, and it's full of bacteria and other microorganisms that bring about chemical changes in the water.