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Geotechnics and Environmental Engineering
Pages 15 (3765 words)
Contaminated sediments have been singled out as a major environmental concern in many areas. Persistant toxic substances that have accumulated in sediments from various sources are a threat to the survival and health of bottom living organisms and their consumers, and can also impair the quality of the surrounding water.
The top of this zone is called the water table. The water table may be only a foot below the ground's surface or it may be hundreds of feet down. Groundwater can be found almost everywhere. The water table may be deep or shallow; and may rise or fall depending on many factors. Heavy rains or melting snow may cause the water table to rise, or an extended period of dry weather may cause the water table to fall. Groundwater is also one of our most important sources of irrigation water. Unfortunately, groundwater is susceptible to pollutants. Groundwater is generally a safe source of drinking water; however, there are concerns that contamination may increase as toxins dumped on the ground in the past make their way into groundwater supplies. Pollutants that contaminate groundwater may be some of the same pollutants that contaminate surface water. Compounds from the surface can move through the soil and end up in the groundwater. For example, pesticides and fertilizers can find their way into groundwater supplies over time. Road salt, toxic substances from mining sites, and used motor oil also may seep into groundwater. In addition, it is possible for untreated waste from septic tanks and toxic chemicals from underground storage tanks to contaminate groundwater. Drinking contaminated groundwater can have serious health effects. ...
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