Sedimentation
Sedimentation is the process through which particulate matter is deposited by natural forces such as wind, water, gravity, or ice, as well as through human activities. This ongoing process plays a crucial role in shaping environments, occurring primarily in low-energy settings where materials accumulate after being transported. While sedimentation can lead to beneficial outcomes like beach rejuvenation and nutrient-rich floodplains that support agriculture, it can also result in negative environmental impacts, such as the degradation of water quality and habitat loss for aquatic life. The balance between these positive and negative effects is delicate and influenced by factors like the size, shape, and mass of particles, as well as the energy available for transport. Human-induced sedimentation often exacerbates natural processes, leading to issues such as increased pollution from industrial waste or the loss of recreational areas due to sediment buildup. Overall, understanding sedimentation is vital for managing both land and water resources effectively, ensuring that the benefits can be harnessed while minimizing adverse effects on ecosystems and human health.
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Sedimentation
DEFINITION: Deposition of particulate matter by wind, water, chemical precipitation, gravity, or ice
Sedimentation, whether the result of natural forces or human influences on nature, can have both negative environmental effects, such as the degradation of water quality, and positive effects, such as beach rejuvenation and growth.
Particulate matter accumulates as sediment through transport and subsequent deposition of materials. Transport mechanisms include wind, running water, gravity, and glaciers. Materials that have been dissolved and transported in solution may be deposited as sediment through chemical precipitation. Sedimentation is an ongoing process, and in a natural system, a delicate balance exists between positive and negative effects.
Sedimentation takes place in low-energy environments. Particle transport distance is a function of particle shape, size, and mass, and the available energy for transport. High-energy transport mechanisms will transport larger particles than low-energy mechanisms, and less energy is required to transport small particles the same distance as larger particles. Sedimentation can result in a degradation of the quality of land or water, or a loss of use of these resources. Degradation can be measured in terms of the identifiable adverse affects on aquatic organisms, wildlife, and humans.
Sedimentation can have negative environmental effects as a result of natural processes or as a result of processes induced by humans. Negative effects from natural processes can result from landslides, mudslides, the migration of dunes in developed areas, and the in-filling of lagoons or lakes that might otherwise provide recreational or commercial opportunities. Natural degradation of water quality results from in areas such as north-central Oklahoma, where large accumulations of salt have precipitated from saline to form the Great Salt Plains along the Salt Fork of the Arkansas River, thereby affecting the chemistry of the Arkansas River.
The of dredged or material, industrial wastes, or other materials into a natural system can affect the chemical, physical, and biological integrity of the system. Industrial wastewaters are a major source of chemicals that may include highly stable compounds that are capable of accumulating in high concentrations through sedimentary processes. Both the sedimentation rate and the individual compound’s rate of solubility in water will affect the of accumulated materials.
Adult freshwater organisms are generally tolerant of the normal extremes of suspended solids, but the introduction of excess materials and resulting sedimentation will kill eggs, larvae, and insect fauna while altering the characteristics of the aquatic bottom environment. Studies have also shown that high concentrations of can interfere with the filter mechanisms of aquatic organisms and the ability of sight feeders to locate prey.
The positive effects of sedimentation can be seen in many natural processes. Beach rejuvenation and growth take place as the ocean’s waves and currents deposit materials in quiet-water environments. Similar land growth takes place in the quiet-water environments of lakes and rivers. In many instances, this process has resulted in substantial land growth that has allowed development of commercial or recreational facilities. The floodplains of rivers are frequently rejuvenated with nutrients needed for agricultural land use through sedimentation. Salt harvested from brine ponds relies on the natural process of chemical precipitation and sedimentation. Sedimentary processes have also been responsible for creating accumulations of materials such as gold and platinum in river placer deposits.
Bibliography
Chiras, Daniel D. “Water Pollution: Sustainably Managing a Renewable Resource.” In Environmental Science. 10th ed. Sudbury, Mass.: Jones and Bartlett, 2014.
"Climate Adaptation and Erosion & Sedimentation." Environmental Protection Agency, 28 May 2024, www.epa.gov/arc-x/climate-adaptation-and-erosion-sedimentation. Accessed 23 July 2024.
Taylor, Kevin G. “Sediments and Sedimentation.” In An Introduction to Physical Geography and the Environment, edited by Joseph Holden. 4th ed. Harlow, England: Pearson Education, 2017.