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Volume :38 Issue : 2 2010
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The Impact of Soil Texture on Nitrates Leaching into Groundwater in the North Governorate,Gaza Strip
Auther : Akram H. Al Hallaq
The main aim of this study is to determine the impact of soil texture on N0 leaching risk into groundwater wells, and to establish a statistical relationship between soil texture and the concentration of nitrates (N0) in the North Governorate groundwater. The study shows that there is considerable variation in the soils in the Governorate. The major part of it consists of light or coarse texture. Seven different types of soil have been recognized and mapped. These soils vary in texture from sand to clay, and in permeability from high to low. On average, 71.5% of the soils of two Horizons (A and B) have a relatively high permeability; 28% have imperfect or moderate permeability; and 0.5% have low permeability. In relation to N0 concentration, almost 94% of the groundwater wells of the Governorate showed a NO concentration of one to four times higher than WHO standards. The study also showed that soil texture affects N0 leaching. Soil with a coarse texture, such as sands, allows NO to leach into groundwater faster than soil with a fine texture, such as sandy clay loam, clay loams and clay. There is a positive relationship between the percentage of sands (in two Horizons A and B) and NO concentration in groundwater wells (r= 0.78, and 0.76 respectively). The average amount of NO concentration in water wells which are located in areas of surface sandy soil was about 128 mg/L. In areas of loamy sand, sandy loam, sandy clay loam, loam, and clay loam, the average is immediately reduced to about 94, 70, 58, 52 and 29 mg/L respectively, as a result of decreasing soil permeability which is responsible for the leaching of water and then the leaching of NO to the underground reservoir.
Key words: Soil texture, Nitrate (NO), Permeability, Leaching, North Governorate.