kaolinite and granite

Activity concentrations of

Topics: Bosnia and Herzegovina; Construction Materials; Kaolin; Mining; Potassium Radioisotopes; Radiation Monitoring; Radium; Serbia; Silicon Dioxide; Thorium

Low-solubility contaminants with high affinity for colloid surfaces may form colloid-associated species. The mobile characteristics of this species are, however, ignored by the traditional sorption/distribution experiments in which colloidal species contributed to the immobile fraction of the contaminants retained on the solids as a result of centrifugation or ultrafiltration procedures. The mobility of the contaminants in subsurface environments might be underestimated accordingly. Our results show that colloidal species of (239)Pu in three-phase systems remained the highest percentages in comparison to both the dissolved species and the immobile species retained on the granite grains (solid phase), although the relative fraction of these three species depended on the colloid types. The real solid/liquid distribution coefficients (K s/d) experimentally determined were generally smaller than the traditional K s/d (i.e., the K s+c/d in this study) by ~1,000 mL/g for the three-phase systems with the mineral colloids (granite particle, soil colloid, or kaolinite colloid). For the humic acid system, the traditional K s/d was 140 mL/g, whereas the real K s/d was approximately zero. The deviations from the real solid/liquid K s/d were caused by the artificially increased immobile fraction of Pu. One has to be cautious in using K s/d-based transport models to predict the fate and transport of Pu in the environment.

Topics: Absorption, Physicochemical; Colloids; Humic Substances; Kaolin; Plutonium; Silicon Dioxide; Soil; Solubility; Solutions; Water; Water Pollutants, Radioactive

Factors regulating the occurrence of high fluoride (F(-)) concentrations in groundwater near Nagar Parkar Town, SE corner of Pakistan have been investigated considering lithological influences. F(-) ion concentrations in groundwater range up to 7.85 with mean value of 3.33 mg L(-1). Plots of major elements and their normative mineral composition reflect granitic composition of the rocks in the study area. Modal mineralogical analysis show high perthite, plagioclase feldspars and quartz, while micas, amphiboles and pyroxenes occur in minor quantities. Water-rock interactions, based on dissolved ions of F(-), SiO(2), Na(+), K(+), Mg(2+), Li(+) and Sr(2+) suggest that fluoriferous groundwater originates from granitic rocks, typically from albite, biotite, hornblende and pyroxene and its alteration products such as kaolin and soil. The Log TDS, Na/Na+Ca ratio, Mg/Ca+Mg and Cl/Sigma anions are significant to review the impact of weathering processes which promote the availability of F(-) ions in the groundwater of study area. Principal component analysis (PCA) also renders close association among F(-) ions and other elements in the rocks and groundwater. Studies on F(-) estimation in the granite rock, china clay, soil and sand samples also indicate the presence of high F(-) concentration in these materials and average values have been found to be 1939, 710, 254 and 16 mg kg(-1), respectively.

Topics: Fluorides; Fresh Water; Geologic Sediments; Kaolin; Pakistan; Silicon Dioxide; Soil