OSMOTIC MODEL TO EXPLAIN ANOMALOUS HYDRAULIC HEADS
OSMOTIC MODEL TO EXPLAIN ANOMALOUS HYDRAULIC HEADS
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DOI：
10.1029/wr017i001p00073
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发表时间：
1981-01-01
影响因子：
5.4
通讯作者：
FRITZ, SJ
中科院分区：
文献类型：
--
作者：
MARINE, IW;FRITZ, SJ
实验室实验表明，压实的粘土作为渗透膜时，他们分离的离子浓度不等的水溶液。从理论上讲，地下水系统中的水力压差可能相对较高。其大小主要取决于跨膜的浓度差、离子类型、粘土类型和孔径。在实验中，由于离子通过粘土泄漏，薄的压实粘土膜通常表现出不同程度的渗透效率。在自然系统中，膜和溶液容器不像在实验室中那样清晰和明确。此外，膜通常是厚的、不均匀的和复合的。在南卡罗来纳州艾肯附近的萨凡纳河电厂的一个埋藏的三叠纪盆地中，人们怀疑渗透作用导致盆地中心的盐水相对于上覆的沿海平原含水层中的淡水略微加压。两口威尔斯井的水头分别为7.88和12.98巴（114.3和188.3 psi），高于沿海平原含水层的水头。这些威尔斯中的每一个的水头近似于由每一个井产生的水的溶液浓度计算的渗透平衡水头（分别为12，000和18，500 mg/l）。其他穿透三叠系盆地顶部和边缘的威尔斯井可能穿透离子泄漏导致盐水较少的区域。因此，这些威尔斯井未被加压。
Laboratory experiments have shown that compacted clays act as osmotic membranes when they separate aqueous solutions of unequal ionic concentration. Theoretically, osmotically induced differential hydraulic pressure in groundwater systems can be relatively high. The magnitude depends primarily upon concentration differences across the membrane, type of ions, type of clay, and pore size. In experiments, thin, compacted clay membranes commonly exhibit varying degrees of osmotic efficiency due to ion leak‐age through the clay. In natural systems the membrane and the solution containers are not as distinct and well defined as they are in the laboratory. Moreover, the membrane is commonly thick, inhomogeneous, and composite. In a buried Triassic basin at the Savannah River plant near Aiken, South Carolina, it is suspected that osmosis causes the saline water in the basin center to be slightly geopressurized in relation to freshwater in the overlying coastal plain aquifer. Two wells have heads of 7.88 and 12.98 bars (114.3 and 188.3 psi) above the head in the coastal plain aquifer. The head in each of these wells approximates the osmotic equilibrium head calculated from solution concentration of water produced by each well (12,000 and 18,500 mg/l, respectively). Other wells penetrating the top and edge of the Triassic basin probably penetrate a zone where ion leakage gives rise to less saline water. Thus these wells are not geopressurized.