Editing Soil erosion (section)

===Sedimentation of aquatic ecosystems===
Soil erosion (especially from agricultural activity) is considered to be the leading global cause of diffuse [[water pollution]], due to the effects of the excess sediments flowing into the world's waterways. The sediments themselves act as pollutants, as well as being carriers for other pollutants, such as attached pesticide molecules or heavy metals.<ref>{{Cite book|author=Da Cunha, L.V.|chapter=Sustainable development of water resources|editor=Bau, João|title=Integrated Approaches to Water Pollution Problems: Proceedings of the International Symposium (SISIPPA) (Lisbon, Portugal 19–23 June 1989)|publisher=Taylor & Francis|year=1991|isbn=978-1-85166-659-1|pages=12–13|chapter-url=https://books.google.com/books?id=79ztZNhaNvMC&pg=PA12}}</ref>

The effect of increased sediments loads on aquatic ecosystems can be catastrophic. Silt can smother the spawning beds of fish, by filling in the space between gravel on the stream bed. It also reduces their food supply, and causes major respiratory issues for them as sediment enters their [[gills]]. The [[biodiversity]] of aquatic plant and algal life is reduced, and invertebrates are also unable to survive and reproduce. While the sedimentation event itself might be relatively short-lived, the ecological disruption caused by the mass die off often persists long into the future.<ref>{{Cite book|author=Merrington, Graham|chapter=Soil erosion|title=Agricultural Pollution: Environmental Problems and Practical Solutions|publisher=Taylor & Francis|year=2002|isbn=978-0-419-21390-1|pages=77–78|chapter-url=https://books.google.com/books?id=ITFYBiQ_-VAC&pg=PA77}}</ref>

One of the most serious and long-running water erosion problems worldwide is in the [[People's Republic of China]], on the middle reaches of the [[Yellow River]] and the upper reaches of the [[Yangtze River]]. From the [[Yellow River]], over 1.6&nbsp;billion tons of sediment flows into the ocean each year. The [[sediment]] originates primarily from water erosion in the [[Loess Plateau]] region of the northwest.<ref>{{Cite journal|title=Estimating soil erosion risk and evaluating erosion control measures for soil conservation planning at Koga Watershed, Ethiopian Highlands|last1=Molla|first1=Tegegne|last2=Sisheber|first2=Biniam|date=2016-09-08|doi=10.5194/se-2016-120|doi-access=free}}</ref>