Water Quality - 9 of 28
Water Quality FAQs - 28 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: Groundwater Quality
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 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.