M. Sarmast, M. H. Farpoor, M. Sarcheshmehpoor, M. Karimian Eghbal,
Volume 18, Issue 68 (summer 2014)
Abstract
Biocalcite infilling and bridging in a sandy soil was studied in the present research. Effects of 2 bacterial species (Sporosarcina pasteurii and Sporosarcina ureae), 3 reactant concentrations (0.5, 1.0, and 1.5 M of urea and CaCl2 mixture), and 6 reaction times (12, 24, 48, 96, 192, and 288 hr) on saturated hydraulic conductivity and mechanical strength of a sandy soil were studied as a factorial experiment. Soil samples were selected from sand dunes of Joopar area, Kerman Province. Bacterial inoculums and reactant solutions were daily added to soil columns. Results of the study showed that S. pasteuriihad had a higher effect on decreasing hydraulic conductivity of the treated samples (11.57 cm/h) compared to the blank (41.61 cm/h) than S. ureae. Increasing reaction times (from 12 to 288 hrs) and reactant concentrations (from 0.5 to 1.5 M) decreased hydraulic conductivity by 49 and 16 %, respectively. S. pasteurii increased strength of treated samples up to 2.6 Mpa pressure compared to S. ureae. Reactant concentrations and reaction times increased soil strength significantly (2.13 and 4.1 Mpa, respectively). Micromorphological observation showed calcite crystals bridging soil particles and filling pore spaces.
M. Sarmast, M. H. Farpoor, I. Esfandiarpoor Boroujeni,
Volume 19, Issue 73 (fall 2015)
Abstract
Physical, chemical, and microscopic properties together with mineralogy are among useful techniques for dating and paleoclimatological interpretation and identification of varnishes. The present research was performed to evaluate the application of stone varnish in dating and landform development investigations in southern dry lands of Giroft area, Kerman Province. The mantled pediment was identified and divided into stable, unstable and moderately stable surfaces due to the type of geological sediments and stone varnish properties. Varnished stones were collected and their physico-chemical properties, petrography and scanning electron microscope characteristics, and clay mineralogy on geomorphic surfaces were studied. Silicon, Al, Fe, and Ca were the dominant elements found in stone varnishes of the area and varnish thickness varied from 100 to 600µm on different stones studied. The results of cation ratio (Ca + K)/Ti showed that the samples from stable surface were older than those on moderately stable and unstable surfaces. Clay coating and infilling were also observed on stones of stable surfaces. Chlorite, illite, palygorskite, smectite, kaolinite and sepiolite clay minerals were found in varnishes studied. Besides, scanning electron microscope images clearly showed layer morphology of rock varnish. The results of the research proved the potential of stone varnish application in relative dating investigations of different geomorphic surfaces in Giroft area.
