[en] Final report summarizing the completed work of the project entitled 'Dissolution of Feldspar in the Field and Laboratory.' One of the highly debated questions today in low-temperature geochemical kinetics centers upon the rate and mechanism of dissolution of feldspar, the most common mineral in the crust. In this project, the mechanisms of feldspar dissolution were investigated by emphasizing experiments with feldspar glass and crystal while comparing surface and solution chemistry. Specifically, laboratory work focused on the structure of altered surface layers on feldspars, the rate of dissolution of feldspar crystal and glass, and the presence of porosity and surface coatings on feldspars. In a complementary field project, the use of Sr concentrations and isotopic ratios were used to calculate feldspar dissolution rates

[en] Moessbauer spectroscopy is a very useful tool in the examination and characterization of ancient pottery sherds. In this study, Moessbauer spectra for sherds and clay from the Warren Wilson Site, a prehistoric Native American (Cherokee) settlement in western North Carolina, were measured. Data from one sherd and samples from two clay beds indicate that the sherd was not made from local clays and was originally fired to 350 C. (orig.)

[en] In the article we try to validate the reason why the shape of the grains of clay minerals is a useful method for identification

[en] The crystal chemistry and surface site reactivity of the phyllosilicate minerals is a key issue for modelling the ion mobility and retardation in clay sediments. Various cation substitutions in the TOT layer of the 2:1 phyllosilicates result in a permanent structural charge near basal plane which is responsible for swelling and the sorption of ions by a cation exchange mechanism. In contrast, the pH-dependent uptake of cations is controlled by protonation/de-protonation reactions on the edge sites of the TOT layer. Various models have been proposed to explain the reactivity of the edge sites based on macroscopic experiments. A detailed understanding of this process on an atomistic level is still missing. We are using electronic structure calculations and ab initio MD simulations in order to understand the mechanism of pH dependent sorption of cations on edge sites of pyrophyllite and the transport properties of aqueous solutions in compacted pyrophyllite. The calculations provide important constrains for the macroscopic surface complexation models of clay minerals. (authors)

[en] This report describes piston corers employing high ambient pressure seawater for the energy source to drive the samplers into clay sediments of the deep ocean. The corers are a unique design using a self-contained hydraulic drive and control system developed especially for the requirements of the Subseabed Disposal Program's In-Situ Heat Transfer Experiment (ISHTE)

[en] Low-permeability soils like silts and clays may act as storage reservoirs for dissolved contaminant mass. As the original source is depleted, back-diffusion may sustain groundwater plumes for decades to centuries or longer. There are some tools available for evaluating back-diffusion from thick clay/silt layers (e.g. Matrix Diffusion ToolKit); however, there are significant limitations for estimating timeframes for back-diffusion from thin layers of clay and silt, and for evaluating the influence of contaminant degradation on back-diffusion timeframe. Use of numerical models may be prohibitive in some cases, particularly for three-dimensional (3-D) models. For example, representing one thin silt or clay unit in a numerical model may require incorporation of dozens to a hundred or more model layers. Representing multiple thin silt/clay units distributed vertically is even more prohibitive. This study presents an innovative approach for simulating diffusion using a local domain approach, which has been incorporated into a new public domain model called In Situ Remediation MT3DMS (ISR-MT3DMS). ISR-MT3DMS was developed based on the MT3DMS framework, and utilizes an array of one-dimensional local domain models for simulating diffusion-dominated processes at different spatial and temporal resolution than the global domain. ISR-MT3DMS also includes the flexible biogeochemical reaction framework from BioRedox (Carey et al., 1998) for simulating natural and enhanced degradation. (author)

[en] The multichannel analysis of surface wave (MASW) has drawn considerable interest in subsoil investigation and characterization. This method has been studied and improved in the last few decades, thereby leading to several combinations of existing active and passive methods. This study aims to identify the presence of marine clay layer using combined active and passive MASW methods. The shear wave velocity profile obtained interpreting clay layer within the range of 70-150 m/s and sand layer within the range of 100-300 m/s. Results suggest that the combined MASW method significantly improves shear wave velocity profiling in shallow and deep soil layers and the results are validated using the cone resistance and shear wave velocity estimated from cone penetration test.Introduction (paper)

[en] Present article of monograph is devoted to protection of land resources. It was found that the issues of rational and ecologically reasonable use of land and water resources and their protection are very actual for Tajikistan.

[en] In this article author investigated variability of properties of massivedepending of particularities of granulometric and mineral composition oftectonics

[en] Currently, geotechnical engineers use stone columns to strengthen weak soils. The usage of stone columns to strengthen soft soil has proven successful, increasing their bearing capacity, reducing the settlement and decreasing the consolidation time. The present study was carried out to investigate the impact of the length of stone columns on the behaviour of soft soils and determine the effective length of stone columns, within which they have the greatest impact on the process of settlement of the soft clay layer. The analysis was performed utilizing a three-dimensional limited distinction numerical model FLAC3D. The results of the study confirmed that with the increase in the length of the stone columns, the settlement of the clay layer decreases. This decrease in settlement is significant to a depth corresponding to the relative length of the piles (L/d) = 10, after that the decrease in settlement practically stops. (paper)