极端干湿循环作用下饱和泥浆红黏土的干缩裂隙发育特征

云贵高原红黏土常经历极端干湿循环过程,为研究极端干湿循环作用对红黏土干缩裂隙发育规律的影响,以昆明呈贡地区红黏土饱和泥浆样为研究对象,在室内进行5次干湿循环试验,通过监测红黏土质量和表面干缩裂隙的形成及其演化过程,分析了极端干湿循环作用对红黏土水分蒸发、干缩裂隙的形成及其演化、表面干缩裂隙网络结构形态的影响.结果 表明...     

GROUNDWATER GEOCHEMISTRY IN THE SEMINOLE WELL FIELD,CEDAR RAPIDS,IOWA1

The City of Cedar Rapids obtains its municipal water supply from four well fields in an alluvial aquifer along the Cedar River in east-central Iowa. Since 1992, the City and the U.S. Geological Survey have cooperatively studied the groundwater-flow system and water chemistry near the well fields. The geochemistry in the alluvial aquifer near the Seminole Well Field was assessed to identify potentially reactive minerals and possible chemical reactions that produce observed changes in water chemistry. Calcite, dolomite, ferrihydrite, quartz, rhodochrosite, and siderite were identified as potentially reactive minerals by calculating saturation indexes. Aluminosiicate minerals including albite, Ca-montmorillonite, gibbsite, illite, K-feldspar, and kaolinite were identified as potentially reactive minerals using hypothetical saturation indexes calculated with an assumed dissolved aluminum concentration of 1 microgram per liter. Balanced chemical equations derived from inverse-modeling techniques were used to assess chemical reactions as precipitation percolates to the water table. Calcite dissolution was predominate, but aluminosilicate weathering, cation exchange, and redox reactions also likely occurred. Microbial-catalyzed redox reactions altered the chemical composition of water infiltrating from the Cedar River into the alluvial aquifer by consuming dissolved oxygen, reducing nitrate, and increasing dissolved iron and manganese concentrations. Nitrate reduction only occurred in relatively shallow (3 to 7 meters below land surface) groundwater near the Cedar River and did not occur in water infiltrating to deeper zones of the alluvial aquifer.     

钢渣吸附除磷性能的试验研究

研究了钢渣的吸附除磷效果并进行机理探讨。结果表明：钢渣采用0．5g,即可在25℃下、2个小时内,将100ml的磷浓度为10mg／L（以磷计）的模拟含磷废水的磷浓度降至0．5mg／L以下,达到磷的国家一级排放标准;钢渣吸附平衡时问为2小时;钢渣吸附除磷的机理主要是沉淀、吸附（表面络合反应）,并辅以静电作用。