Đất, nước ngầm, ô nhiễm và dưới bề mặt 5,1 Tính chất của đất Tiềm năng nước là luôn luôn một băng tải của các chất gây ô nhiễm, ở đâu có thể được Hoặc là năm đất rào cản đối với sự di chuyển chất gây ô nhiễm, vận chuyển chất gây ô nhiễm. Ma trận đất văn phòng phẩm làm chậm quá trình chuyển đổi của nước ngầm và bề mặt vững chắc để CDN nào trái thanh lương trà Cung cấp chất gây ô nhiễm, Trì hoãn hoặc dừng chuyển động của họ. Mặt khác, có thể di chuyển. | 5 Soil Groundwater and Subsurface Contamination NATURE OF SOILS Water is always a potential conveyor of contaminants whereas soil can be either an obstacle to contaminant movement or a contaminant transporter. The stationary soil matrix slows the passage of groundwater and provides solid surfaces to which contaminants can sorb delaying or stopping their movement. On the other hand soil can also move carried by wind water flow and construction equipment. Moving soil like moving water transports the contaminants it carries. Predicting and controlling pollutant behavior in the environment requires understanding how soil water and contaminants interact. That is the subject of this chapter. Soil Formation Soil is the weathered and fragmented outer layer of the earth s solid surface initially formed from the original rocks and then amended by growth and decay of plants and organisms. The initial step from rock to soil is destructive weathering. Weathering is the disintegration and decomposition of rocks by natural physical and chemicalprocesses. Physical Weathering Physical weathering causes fragmentation of rocks increasing the exposed surface area and thereby the potential for further more rapid weathering. Common causes of physical weathering are Expansion and contraction caused by heating and cooling. Stress forces caused by mineral crystal growth and the expansion and contraction of water when it freezes and melts in cracks and pores. Penetration of tree and plant roots. Scouring and grinding by abrasive particles carried by wind water and moving ice. Unloading forces that arise when rock-confining pressures are lessened by geologic uplift erosion or changes in fluid pressures. Unloading can cause cracks at thousands of feet below the surface. 2007 by Taylor Francis Group LLC. Chemical Weathering Chemical weathering of rocks causes changes in their mineral composition. Common causes of chemical weathering are Hydrolysis and hydration .
