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An aquifer, according to the Oxford dictionary is a body of permeable rock that can contain or transmit groundwater. Aquifer Susceptibility is the inherent ability of a formation to accept and transmit liquids (potentially including contaminates). Certain areas of the United States are becoming more reliant on groundwater to meet the needs of the population. == Causes == Everyday, roughly 4.2 trillion gallons of precipitation falls in the United States. About one fourth of that will make its way through the aquifers and become ground water. Shallow and permeable water tables tend to be more susceptible to contamination. In addition, the less rain an area receives the more concentrated the contamination will be. Evotranspiration can also decrease the amount of water moving downward. Some aquifer susceptibility does happen naturally. Natural chemicals can seep through the aquifers from nearby soil and rocks. However, too much of this can be bad. One of the most common concerns is the amount of chloride and dissolved solids that are found in the water. Federal standards state the maximum for dissolved solids are 500 mg/L, and 250 mg/L for chloride. Dissolved solids and chloride are often found in coastal aquifers and in aquifers deeper than a few hundred feet. Iron and Magnesium can also affect the groundwater. It can also reduce the efficiency of well pumping. While there is not usually a huge amount of nitrogen in groundwater, human involvement can increase it. Federal standards state that the maximum level of nitrogen in groundwater is 10 mg/L. If humans do not interfere, levels generally stay around 0.2 mg/L. However, if levels exceed 3 mg/L, this could mean human involvement. Usually nitrogen is not harmful. But, it has been found to cause methemoglobenimia in infants. The susceptibility of the aquifer also depends on if the aquifer has large or small pores. A rock that has low conductivity level is known as an aquitard. This can constrict the amount of water that is available to use. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Aquifer Susceptibility」の詳細全文を読む スポンサード リンク
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