Suspended sediments

2010-11-09T18:46:00.000-08:00

Suspended sediment is defined by the United States Environmental Protection Agency as fine material or soil particles that remain suspended by river current until deposited in areas of weaker current. Suspended sediment is of important environmental concern because of the problems associated with it. By volume and mass; sediment is the greatest water pollutant (Botkin and Keller 2005). Suspended sediments make up the bulk of sediment transport from rivers to the ocean (Asselman, 1997). Accumulation of sediments in river channels can reduce the flow capacity of streams, cause siltation of in stream habitat, increase the risk of flooding, and accelerate reservoir filling (Morgan, 2005).

Suspended sediments can pollute water and may serve as a catalyst, carrier and storage agent for pollutants. Suspended sediments can carry bacteria, organic matter, pesticides, heavy metals, phosphorous and nitrogen (excessive amount of nitrogen can cause methemoglobinemia also known as the ‘blue baby syndrome’). Suspended sediment may reduce sunlight penetration into water, thereby reducing the production of microorganisms, which begin the aquatic food chain. Sediments can cover and damage plants and fish egg at the bottom of rivers (Miller and Gardiner, 2001).

Suspended sediment concentration in rivers is highly variable in time; it is generally high during periods of increased discharge. A major part of the annual load of suspended sediment and its associated contaminants are transported through rivers during flood events, a relatively short period of the year (Steenkamp and Ludikhuize, 1999; McKee et al 2002).

Most evidence suggests that much of the observed suspended sediment load in rivers is derived from erosion of agricultural land (Walling and Zhang, 2004).