关键词：饮用水 化学 用水 化学物质 水中
Drinking Water: Man-made Chemicals
Many Nebraskans are concerned about the effects some of the man-made chemicals that have become part of everyday life may have on their water supply. As the name implies, these chemicals do not exist in nature but were made by man. With proper storage and use of these chemicals and with proper well construction, the risks to groundwater from the chemicals are low and the benefits are many.
In some areas of the state, however, industrial solvents, manufacturing chemicals, ammunition wastes, pesticides and grain fumigants have been detected in groundwater. In many cases the sources of the contamination could be identified, clean-ups are underway, and alternative water supplies are being used. Often the contamination occurred many years ago.
Scattered throughout Nebraska are areas that have both sandy soils and shallow water tables. The high permeability of these soils, combined with the relatively short distance to the water table, make these areas particularly sensitive to contamination. Excessive rainfall or over-irrigation can cause downward movement of water through the soil profile. Those man-made chemicals which do not bind strongly to soil particles can be carried with the downward moving water and eventually can be leached to the groundwater.
Leaching and groundwater contamination also takes place in areas without sandy soils or a high water table, only at a slower rate.
Activities near a well, particularly mixing or storing chemicals, potentially can contaminate the water supply. In some areas, depending on the relative location of the well and sites where various man-made chemicals are used, contamination could occur from normal application and use. Used motor oil dumped on the ground, spilled fuel near storage tanks, pesticides spilled during mixing and loading, and improperly dumped household products are all examples of man-made chemicals that could leach to groundwater. In addition, leaking underground fuel tanks can contaminate groundwater without visible evidence on the surface.
Man-made chemicals also can enter groundwater through more direct routes. Improperly constructed wells or older wells with leaks around or through the casing can allow contaminants to seep into groundwater. Abandoned wells that are not properly sealed also provide direct pathways to the aquifer. Pesticide applications near such wells or any chemical spills on the surface could potentially contaminate groundwater if surface runoff moves toward the well.
Prevention of spills and immediate cleanup of any spills are among the best ways to prevent contamination of groundwater with man-made chemicals. Proper site selection and construction of domestic water wells can reduce potential contamination of drinking water. Wells that are no longer needed should be properly decommissioned to eliminate direct conduits to the aquifer.
Most man-made chemicals are undetectable in water without testing since they are colorless, odorless, and tasteless in the low concentrations that may occur. Public water supplies are required to be tested regularly and treatment is used, if needed, to meet established drinking water standards. If your water supply is a private well, you should consider testing if a chemical has been spilled near the well or if there is another reason to suspect contamination. Unfortunately, there is no single test for man-made chemicals and individual tests can be expensive, from
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