The International Information Center for Geotechnical Engineers

Sediment Quality Guidelines (SQGs): A Review and Their Use in Practice

 

 

SEDIMENT CONTAMINATION BACKGROUND

Sediments, as this paper will explore them, are defined as free particles of soil found at the bottom of a water body, whether it be clay, sand, organic material, or silt. They originate from both erosion and decomposition of natural elements, animals, and plants. When the sediments are exposed to pollutants through water or soil, they become contaminated over time.

The locations of contaminated sediments are very widespread. The most concerning areas that are affected include the Atlantic and Pacific coasts, the Gulf of Mexico, the Great Lakes Region, and many inland waterways (EPA, 1999). Research in the area of contaminated underwater sedimentation has slowly developed since the 1970’s when environmental policy was first becoming relevant.

The most prominent contaminants are called Polycyclic Aromatic Hydrocarbons (abbreviated PAH’s), which include petroleum and byproducts of petroleum. Other contaminants, like dichlorodiphenyltrichloroethane (DDT) and Polychlorinated biphenyl (PCB) are concerning because their decay half-life is extremely long, which leads them to stay at high levels of contamination for long periods of time (Ferrarese, Andreottola, Oprea, 2007).

 

Contamination of sediments is mostly dangerous because of how it travels up the food chain, ultimately becoming harmful to animals and humans. When contamination starts in the soils that are home to plant seeds, the toxins travel through the soil and make the plants themselves toxic. As organisms eat these plants and larger animals eat these organisms, the toxins become more potent in the process of biomagnification (EPA 1999).

By the time the contaminants reach the top of the food chain, mutations or deadly diseases can result. If small fish closer to the bottom of the food chain and digesting the free, toxic sediments cannot handle the mutations, their population will die out quickly. The biodiversity of the ecosystem will decrease, causing environmental problems that could become detrimental.

The main source of problems concerning human health effects comes with the consumption of fish. Starting in the 1990’s, fish consumption advisories were put out in the Great Lakes area due to health concerns. Potential risks for humans include neurological disorders and cancer.

The 1970’s began an influx of environmental policies that began addressing problems that the public was not aware of. The Clean Water Act, Clean Air Act, Comprehensive Environmental Response, Compensation, and Liability Act, and Water Development Act all became legislature within a couple of decades. The Water Resources Development Act of 1992 (WRDA) specifically addressed the contaminated sediments issue for the first time. It caused Congress to order the Environmental Protection Agency to write the National Sediment Quality Survey, which found there to be contaminated sediments in bodies of water in every state, while most notably outlining the severe problems in the Great Lakes region (EPA, 1992).

The sources of these types of contaminants vary, but can mainly be traced back to human waste disposal sites. Point sources, such as sewage treatment plants, sanitary sewers, stormwater drains, and waste industry discharge sites can be traced to specific areas. Contamination sources that are more widespread, like stormwater runoff, mining and manufacturing runoff, and atmospheric pollutant spread, are known as non-point sources, as they are more difficult to trace back to origins.  Since these sources range from public to privately owned, there is not one sector of government that is left responsible for regulating sediment contamination.  

 

Add comment

NOTE: The symbol < is not allowed in comments. If you use it, the comment will not be published correctly.

Security code
Refresh
*Please insert the above-shown characters in the field below.

The Geoengineer.org Corporate Sponsors: