Tuff Material Research Articles

Geology, morphology and mineralogy of sulfide-carbonate hydrothermal-bacterial structures on the surface of Tessel paleovolcano lava (south coast of Crimea)

Research subject. Sulfide-carbonate hydrothermal-bacterial structures on the surface of Tessel paleovolcano lava. Materials and methods. The structures under study were found during detailed geological works. Petrographic thin sections were studied using an Olympus Bx5 microscope. Carbonate and sulfide samples were examined using an RZMMA-202M scanning electron microscope. Results. For the first time, the contacts of the studied structures with their enclosing siltstones and mudstones were described. The structures are of tubular and flat shapes. In terms of mineral composition, the structures exhibit three zones: central, lateral and that of bacterial overgrowth. The middle part of the central zone features a fluid channel with inclusions of quartz, barite, nakrite, galena, chalcopyrite, pyrrhotite, sphalerite, pyrite, shells of largefauna, ash and tuff material. Spherulites and microtubular carbonate formations testify to the participation of bacterial and archaean communities in the construction process. The study of carbonates and sulfides confirmed the use of deep fluids by prokaryotes. Conclusion. The main role in the formation of the sulfide-carbonate hydrothermal-bacterial structures under study belonged to the community of prokaryotes and fluids from the depths. The external morphology of the studied structures along with the presence of mineralogical zonality, a fluid channel, oil products, and oases of life with a large fauna indicate the similarity of their formation conditions to those of sulfide-carbonate smokers of the Piip volcano. Some differences in the mineral composition are associated with different depths and fluids of their formation.

The characteristics and genetic mechanisms of the Upper Permian Shangwuerhe clastic reservoir in the eastern Junggar Basin, Northwest China

In this paper, the lithology, pore type, throat structure, and physical characteristics of the sandstone and conglomerate reservoirs of the Upper Permian Shangwuerhe Formation in the Fukang Sag of the Junggar Basin were analyzed through rock cast thin section, scanning electron microscopy, fluid inclusions, piezometric mercury, and porosity–permeability analysis. In addition, the reservoir densification mechanism and the genesis of deep effective reservoirs were discussed. The results show that the reservoir is dominated by lithic sandstone (or lithic sandstone conglomerate). The lithic fragments primarily comprise tuffaceous volcanic rocks, supported by grains and cemented by clay, carbonate, authigenic quartz, and laumontite. The reservoir properties are characterized by extra-low porosity and permeability, and the pore type is dominated by inter- and intragrain dissolved pores of lithic fragments, feldspar, and quartz. The pore connectivity is poor due to poorly sorted extra-fine throat channels. The tightness of the reservoir.is due to the strong cementation of calcite, chlorite, montmorillonite, illite-montmorillonite mixed layer, authigenic quartz, and laumontite. Furthermore, the large amount of Ca2+ released by the hydration of tuff rock debris and intermediate–basic volcanic rock debris and the CO2-rich thermal fluid from the deep layers cause the development of several calcites. The formation of several montmorillonites is mainly related to the alteration of filled volcanic ash, and the hydration of volcanic tuff material primarily causes the development of laumontite cementation. The dissolution of feldspar and various volcanic lithic fragments by acidic fluids triggers the physical improvement of the reservoir in the local section.

Changes in Yield and Antioxidant Enzyme Content of Tomato Plant Depending on the Application of Microorganism Injected Tuff Material

ABSTRACT Tomatoes are one of the most popular and widely grown vegetables in the world. Due to the excessive and unconscious use of chemical fertilizers used in tomato cultivation for high yields, economic and environmental problems such as loss of soil fertility and pollution can occur. So, in this study, Plant Growth Promoting Rhizobacteria (PGPR) bacteria were applied to the soil in a tuff carrier medium and the yield parameters of tomato plants were investigated. Bandita F1 tomato seedlings were used in this study. Approximately 108 cfu g−1 bacteria were added to the medium sized tuff material (8 × 8 × 11 mm). The tuff materials with PGPR were applied to the soil according to the experimental group. A trial model was created as the plots in which bacteria inoculated tuff material was applied and the plots without bacteria were applied. Approximately 50 g of Tuff + PGPR material was applied to each plant root and irrigated according to the water requirement of the plants. The highest yield (6016 kg da-1) was obtained when tuff inoculated with bacteria was applied. In this application, an increase of 9.0% was recorded compared to the control group. In the application of tuff inoculated with bacteria, the amount of chlorophyll increased by 4.66%, membrane permeability by 3.0% and the amount of photosynthesis by 3.91% compared to the control group. It was found that the use of tuff materials inoculated with bacteria would have a positive effect on the yield of the tomato plant.

Study on the Strength Characteristics and Mechanism of Weathered TUFF

Abstract: Many countries in the world has a large number of tuff like cultural relics that have many historical history. These kinds of cultural relics tuff have experienced many natural weathering in the long historical years. Natural weathering like air pollution since industrialization, acid rain erosion and many different degrees of artificial damage, they are suffering from different degrees of surface degradation and decay, erosion and even destruction and a strong typhoon effect. Under consideration and effective protective measures are not taken, irreparable losses will be caused. People who are coming for tourism to look at the historical and cultural relics are in danger. Therefore, it is urgent to deeply study the weathering damage mechanism of stone cultural relics, and to develop stone cultural relics protection materials and construction technical measures. In this paper we will research by understanding the theoretical characteristics and relationship between tuff strength and weathering degree and weathering damage mechanism of stone, and characteristics of rock and mineral composition so that we can theoretically address by studying the weathering damage mechanism. Keywords: Natural stone decay; tuff materials, rock mechanics, weathering damage.

Origin and enrichment of borates in a Late Paleozoic alkaline lake-playa deposit, Junggar Basin, NW China

Reedmergnerite (NaBSi3O8) and searlesite (NaBSi2O6·H2O) are rare borates minerals over the world. In the Late Paleozoic Fengcheng Formation of the NW Junggar Basin, NW China, the two borates, especially reedmergnerite, occur as locally abundant minerals of potential economic interest. Here, petrology, minerology, and boron isotopes of different reedmergnerite occurrences in the Fengcheng Formation were systematically studied to explore its enrichment mechanism in sedimentary rocks. Reedmergnerite in the Fengcheng Formation is a temperature-controlled (crystallizing at 55–180 ℃, mainly at 90–110 ℃) and diagenetic replacive mineral. In the lake center deposits of the Fengcheng Formation, reedmergnerite is confined within sodium carbonate beds or nodules and shows a clear replacement of sodium carbonate minerals. In the lake slope deposits, reedmergnerite is also very abundant and mainly replaces calcite or dolomite-ankerite within sub-horizontal fractures or shortite/eitelite crystal molds, occasionally seen replacing bedded searlesite or growing both replacively and displacively in organic-rich matrix. No significant reedmergnerite is found in the lake margin deposits. Boron isotopes of reedmergnerite-bearing samples (–0.04‰ to + 7.69‰) are higher than those of lacustrine mudstone samples (–14.2 to + 2.79‰) and overlap those of ignimbrite samples (+2.37 to + 3.87‰). Boron for diagenetic reedmergnerite formation was primarily inherited from the original hydrothermal fluids that flowed into lakes and its concentration was influenced by lake water pH and salinity. Potential early boron reservoirs were searlesite, sodium carbonates, organic matter and tuff materials. Fluids responsible for reedmergnerite replacement were weakly acidic. CO2 generated by organic matter degradation-maturation and carbonate dissolution acted as a mineralizer to promote reedmergnerite formation at a lower temperature range than the previously synthetic temperatures (>270 ℃). Enrichment of reedmergnerite in sedimentary rocks requires a primary volcanic-related evaporated lake with high organic productivity, and meanwhile a deep burial environment, at best reaching the depth of oil generation window.

Pendekatan Hidrogeomorfologi Dan Pendugaan Geolistrik Untuk Identifikasi Potensi Airtanah Di Jedong Malang

This study aims to identify the potential groundwater in Jedong, Malang, East Java. The hydrogeomorphological approach is a suitable approach to describe the relationship between hydrological and geomorphological processes on and below the earth's surface. The survey of geoelectricity complements the hydrogeomorphological approach. It will give a better description of the groundwater conditions below the earth's surface. Based on the research, there are 2 hydrogeomorphological units in the study area, which are: Volcanic Foot Valley Unit and Volcanic Foot Ridge Unit. The best groundwater potential is in Volcanic Foot Valley Hydrogeomorphological unit, namely Awar-awar Valley and Cokro Valley. The valleys are dominated by gully erosion and landslides. They have surface deposits up to a depth of 7 meters, and lots of outcrops of breccia, pumice, and andesite boulders. The valley’s springs discharge between 56 - 198 m3/day. The average infiltration rate in the valley is 1776 mm / hour, with sandy soil material. The best aquifer consisting of sandy material is more than 10 meters in depth, based on the geoelectrical survey. Water in the aquiclude layer, cannot be exploited because it is breccia and tuff material. The Sawah valley cannot be exploited further because the groundwater potential is very low. This can be identified by the thick water outflow seepage. In the Volcanic Foot Ridge Hydrogeomorphological unit, the groundwater potential is also very small. Hydrogeomorphically, water will flow down the slope to the valley. It will reduce the infiltration rate. In general, the ridge area is only used for settlement, while the slopes are used for dryland agriculture. The geoelectric analysis results show that the groundwater potential is at a depth of more than 45 meters. This research’s results show that the combination of the hydrogeomorphological approach and the geoelectric use will provide a better description of the potential groundwater.

Effects of Bacterial Inoculated Tuff Material on Yield and Physiological Parameters of Grape (Vitis vinifera) Plant

Effects of Bacterial Inoculated Tuff Material on Yield and Physiological Parameters of Grape (Vitis vinifera) Plant

Effect of stabiliser type on the physical and mechanical properties of tuff material

The properties of tuff blocks and the feasibility of using these blocks in construction were examined. This paper presents an experimental study on the characterisation of tuff blocks stabilised with cement, lime, alfa fibres and human hair. The use of tuff raises many questions and poses challenges, but it has been chosen to play a major role in road constructions in recent years because tuff soil is one of the most abundant natural materials. The disadvantage of tuff blocks is their low resistance to water damage. The main objective of this work was to study the mechanical properties (compressive and tensile strength, and speed of sound resistance) and durability (water absorption and wetting–drying) of tuff blocks. The experimental results showed that 80% tuff + 20% clay + 12% cement bricks give better results and that the impact of fibres on tuff blocks is unfavourable due to their heterogeneity or distribution, low matrix adhesion and very high water absorption. These factors affect the conditions under which tuff soil materials can be used in construction.

WATER SATURATION INDUCED CHANGES IN THE INDIRECT (BRAZILIAN) TENSILE STRENGTH AND THE FAILURE MODE OF SOME IGNEOUS ROCK MATERIALS

The present study concentrates on water induced strength reduction and variation of the failure mode in indirect (Brazilian) tension tests of several igneous rock materials under three moisture cases of oven-dry, air-dry and fully saturated states. In this respect, two andesite and three tuff materials which contain no visible flaws were subjected to indirect tensile strength tests using the Brazilian disc method. Once the tension tests were carried out, photographs of the broken samples were taken to investigate the changes in the failure mode. As a result, it was found that tensile strengths of the samples were highly reduced with the presence of the water and the natural humidity. Additionally, it has been deduced that the failure mode of the samples mainly shifts to central fracturing with the presence of natural moisture and saturation. Although the central crack is the ideal type for the theory of Brazilian tensile strength determination, indefinite contact properties like contact angle and frictions are some notable issues to make only considering failure shapes for the validity of the test results misleading. Keywords: Failure mode; Igneous Rocks; Strength reduction; Tensile strength DOI 10.35180/gse-2020-0031

INDONESIAN NANOCLAYS FOR THE REMOVAL OF NITRATE IN LIQUID WASTE CONTAINING PALM OIL MILL EFFLUENT

Land application of liquid waste containing palm oil mill effluent (LW-POME) as soil ameliorant can cause water contamination due to its high content of nitrate if improperly treated. Indonesia is rich with volcanic tuff materials that contain variable charged soil clay minerals. This study was aimed at to extract nanoclays (fraction sized <200 nm) from volcanic tuffs of Mt. Salak, West Java, Indonesia, and evaluate their potential use as adsorbent of nitrate in LW-POME. By applying dispersion, ultrasonication, centrifugation, and dialysis separation techniques, it could be extracted positively charged nanoclays nc3 and nc4 from the respectively tuff materials tv3 and tv4. Their potential use as natural adsorbent of nitrate as anionic contaminant was evaluated using Langmuir isothermal adsorption model. After 48 h equilibration, it could be extracted 4.33 mg nc3/g tv3 and 7.73 mg nc4/g tv4 with nitrate adsorption maxima of 48.3 and 40 mg/g for nc3 and nc4, respectively. The removal of nitrate in the LW-POME from 62 to 20 mg/L as to comply with the Indonesian liquid waste quality standard required 29.81 mg nc3/L or 39.34 mg nc4/L. The extracted nanoclays were considered prospective to be utilized as natural adsorbent for nitrate removal in LW-POME.
 Keywords: anionic contaminant, natural adsorbent, nitrate adsorption, volcanic tuff

Petrogenesis study of quaternary volcanic rocks based on petrography analysis in Lubuk Nipis Village, Muara Enim District, South Sumatra

This study aims to identify the characteristics of quartz volcanic rocks as well as their existing source and process of formation in the Lubuk Nipis area of Muara Enim Regency, South Sumatera Province. In conducting this study, field observation is required to obtain primary data directly and then petrography analyze is needed to analyze volcanic rock samples obtained during field observation. There are 3 types of rock units generated by volcanic activity during the quaternary period in the study area. The three units of rock are, among others, units of andesite intrusion (Qpva), units of andesite lava (Qhv), and units of tuff lapilli & tuff breksi (Qhv). In units of andesite intrusion visible porphyritic crystal texture with Plagioclase minerals become the most dominating minerals with the emergence of other primary minerals such as Quartz, Feldspar, Biotite, Hornblende and Pyroxene. Andesite lava comes with 2 different types of characteristics, porphyritic and microporfiritic texture. There are also seen the flow texture that shows the lava flow process during the formation of rocks in andesit lava units. While other units of rock that is unit of tuff lapilli & tuff brecchia is a product of pyroclastic fall. This unit has a composition of tuff material that dominates, also present are crystalline materials such as plagioclase, quartz, feldspar, and biotite. Further assisted by the analysis of DEM (Digital Elevation Model) to see the geometry of the spread of volcanic facies, can be interpreted the order of formation of rock units in the study area.

Contrasting perspectives on the Lava Creek Tuff eruption, Yellowstone, from new U–Pb and 40Ar/39Ar age determinations

The youngest major caldera-forming event at Yellowstone was the ~ 630-ka eruption of the Lava Creek Tuff. The tuff as mapped consists of two major ignimbrite packages (members A and B), linked to widespread coeval fall deposits and formation of the Yellowstone Caldera. Subsequent activity included emplacement of numerous rhyolite flows and domes, and development of two structurally resurgent domes (Mallard Lake and Sour Creek) that accommodate strain due to continual uplift/subsidence cycles. Uplifted lithologies previously mapped on and adjacent to Sour Creek dome were thought to include the ~ 2.08-Ma Huckleberry Ridge Tuff, cropping out beneath Lava Creek Tuff members A and B. Mapped outcrops of this Huckleberry Ridge Tuff material were sampled as welded ignimbrite (sample YR345) on Sour Creek dome, and at nearby Bog Creek as welded ignimbrite (YR311) underlain by an indurated lithic lag breccia containing blocks of another welded ignimbrite (YR324). Zircon near-rim U–Pb analyses from these samples yield weighted mean ages of 661 ± 13 ka (YR345: 95% confidence), 655 ± 11 ka (YR311), and 664 ± 15 ka (YR324) (combined weighted mean of 658.8 ± 6.6 ka). We also studied two samples of ignimbrite previously mapped as Huckleberry Ridge Tuff on the northeastern perimeter of the Yellowstone Caldera, ~ 12 km ENE of Sour Creek dome. Sanidines from these samples yield 40Ar/39Ar age estimates of 634.5 ± 6.8 ka (8YC-358) and 630.9 ± 4.1 ka (8YC-359). These age data show that all these units represent previously unrecognized parts of the Lava Creek Tuff and do not have any relationship to the Huckleberry Ridge Tuff. Our observations and data imply that the Lava Creek eruption was more complex than is currently assumed, incorporating two tuff units additional to those currently mapped, and which themselves are separated by a time break sufficient for cooling and some reworking. The presence of a lag breccia suggests that a source vent lay nearby (< ~ 3 km) for some of the tuffs and that the Yellowstone Caldera boundary in this area could be reconsidered.

Evaluation of Absorption Process for Heavy Metals Removal found in Pharmaceutical Wastewater

This study focused on the adsorption/absorption process of natural volcanic tuff, its application, kinetics, efficiency, velocity and selectivity order in removing heavy metals found in pharmaceutical wastewater. Series of experiments were conducted in batch-wise and fixed-bed columns to study the removal performance and selectivity sequence of mixed metal ions (Pb2+, Cr6+, Cu2+, Zn2+and Fe3+) in aqueous solution using natural volcanic tuff material as adsorbent. The main purpose of this study is to highlight the economical application of the method in treatment of pharmaceutical wastewater.

Investigation of Using Waste Welded Tuff Material as Mineral Filler in Asphalt Concrete

In this paper, the welded tuff waste- known as koyke in Isparta region - was used in the hot mix asphalt (HMA) as mineral filler for reduction of the moisture susceptibility of HMA. Optimum binder content was assessed with Marshall Design Method. First of all, welded tuff was substituted as filler with limestone filler in proportion of 50% and 100%. After that Marshall Stability test was performed on specimens. The results showed that the 50% substitution was more effective than the 100% substitution. Therefore, welded tuff was substituted with limestone filler in proportion of 25%, 50%, 65% and 75%. Next, Indirect Tensile Strength test was practiced on the fabricated specimens and the results were assessed. According to the Indirect Tensile Strength results, welded tuff with 65% was given higher strength than the limestone filler. As a result, it has come up that welded tuff can be used as mineral filler in the hot mix asphalt.

Polarizing microscope observations of pottery from the Yashiro sites, Nagano Prefecture, Central Japan

Inhabitants of the Japanese archipelago historically relied on pottery constructed from clay and sand and fired at approximately 700–900 °C using fuel. This pottery was used from the Jomon to Yayoi periods (13,000 BC–250 AD) despite large cultural change between them. The workmanship of pottery largely depends on the quality of the resources. This study identifies the pottery paste of locally-made pottery and researches the relationship between Jomon and Yayoi pottery. For this purpose, pottery excavated from the Yashiro sites, located in Chikuma City of Nagano Prefecture, which was intermittently produced from the Jomon period to medieval times, was sectioned for microscopy study. The 119 samples of pottery paste were observed under a polarizing microscope and materials were qualitatively classified according to type, size, and quantity of sand fragments (rocks and minerals). Five main categories of ancient pottery were identified. Locally-made pottery in the Jomon period was mainly derived from Susobana tuff material, approximately 5 km from the Yashiro sites. However, this pottery paste was replaced in the Yayoi period by epidote-rich groups. This result suggests that the technical tradition of Jomon potters ceased, and was replaced by new pottery during Yayoi period. The altered distances to pottery resources and the advent of new large village may signify that production zone also changed between the Jomon and Yayoi periods. The new pottery may have been produced in a specific village and become widely accepted. This paper presents the first proposition to the production systems of Jomon and Yayoi pottery by examining the petrology of excavated samples at sites intermittently occupied by humans during the last 4,300 years.

Natural zeolites for heavy metals removal from aqueous solutions: Modeling of the fixed bed Ba2+/Na+ ion-exchange process using a mixed phillipsite/chabazite-rich tuff

The efficiency of Ba2+ removal from aqueous solutions by means of an ion exchange process was investigated. More specifically, a natural zeolitic tuff, namely a Campanian ignimbrite containing both chabazite and phillipsite as exchanger phases was used, and the effect of Ba2+ concentration was studied. The selected material, previously converted into its Na+ form, was used in a laboratory scale fixed bed column, and the kinetics of Ba2+ removal were studied at different concentrations, ranging from 50 to 500g/m3. In all the experiments a very high selectivity of the tuff material towards Ba2+ was observed. The experimental data were interpreted using a diffusional model, based on the Linear Driving Force (LDF) approximation. The model accounted for the presence of two zeolitic phases in the tuff and for mass transfer limitations in both the liquid phase and tuff particles. The model interpreted the data satisfactorily, enabling it to be established that both the internal and external mass transfer resistances played a key role in the kinetics of the ion exchange process.

Unusual lapilli tuff ejecta erupted at Stromboli during the 15 March 2007 explosion shed light on the nature and thermal state of rocks forming the crater system of the volcano

Textural and mineralogical study of high-temperature, angular blocks erupted during the Stromboli explosion of 15 March 2007 was used to make inferences on the nature and thermal state of rocks forming the subsurface of the volcano' summit crater terrace. The studied ejecta consist of lapilli tuff that formed as a result of the transformation and high temperature induration (sintering) of the basaltic scoriae, lapilli and ash originally accumulated as loose tephra during the current activity of the volcano. The main processes leading to the tephra transformation were investigated through microstructural observations, mineral and glass analyses (SEM-EDS and EMP analyses). Investigations revealed that subsolidus reactions and partial melting of the tephra occurred, at temperatures higher than 600°C and under variable fO2 conditions from QFM to HM buffering curves. In some blocks, evidence of high-T reheating and partial melting at the expense of secondary hydrothermal minerals was also observed. In order to track the subsolidus reheating history of the basaltic pyroclasts, a detailed study of the pseudomorphic phases and reactions after olivine, driven by iron oxidation under high-T conditions, was performed. The observed mineralogical transformation suggests that the lapilli tuff material, originating from the burial of tephra routinely accumulated by persistent Strombolian explosions within the crater terrace, were in some cases altered by the circulation of acidic fluids and were in any case reheated due to isotherm rise forced by high heat flux and gas streaming delivered by the underlying magma system. It is worth noting that the ejection of these unusual volcanic lithotypes was possible because a few days before the 15 March 2007 event, the craters were clogged with lapilli tuff material that slid into the crater bottom between 7 and 9 March. Findings of this study suggest that the scattered permanently active vents and shallow conduits of Stromboli are surrounded sideways and underneath the crater terrace, by a fairly large volume of high temperature rocks with variable degree of compaction, sintering up to partially melted. Such a spectrum of rock types is in good agreement with the conceptual model of prominent thermal zoning all around (sideway and upwards) the active magmatic system. We speculate that continuous migration upwards of isotherms led to transformation and partial melting of the normal Strombolian tephra.

Numerical Investigation of the Dynamic Compressive Behaviour of Rock Materials at High Strain Rate

The dynamic compressive strength of rock materials increases with the strain rate. They are usually obtained by conducting laboratory tests such as split Hopkinson pressure bar (SHPB) test or drop-weight test. It is commonly agreed now that the dynamic increase factor (DIF) obtained from impact test is affected by lateral inertia confinement, friction confinement between the specimen and impact materials and the specimen sizes and geometries. Therefore, those derived directly from testing data do not necessarily reflect the true dynamic material properties. The influences of these parameters, however, are not straightforward to be quantified in laboratory tests. Therefore, the empirical DIF relations of rock materials obtained directly from impact tests consist of contributions from lateral inertia and end friction confinements, which need be eliminated to reflect the true dynamic material properties. Moreover, different rocks, such as granite, limestone and tuff have different material parameters, e.g., equation of state (EOS) and strength, which may also affect the DIF of materials but are not explicitly studied in the open literature. In the present study, numerical models of granite, limestone and tuff materials with different EOS and strength under impact loads are developed to simulate SHPB tests and to study the influences of EOS and strength, lateral inertia confinement and end friction confinement effects on their respective DIFs in the strain rate range between 1 and 1,000 s−1. The commercial software AUTODYN with user-provided subroutines is used to perform the numerical simulations of SHPB tests. Numerical simulation results indicate that the lateral inertia confinement, friction confinement and specimen aspect (L/D) ratio significantly influence DIF obtained from impact tests and the inertia confinement effect is different for different rocks. Based on the numerical results, quantifications on the relative contributions from the lateral inertia confinement and the material strain rate effect on DIF of granite, limestone and tuff material compressive strength are made. The effects of friction coefficient, L/D ratio and rock type on DIF are discussed. Empirical relations of DIF with strain rate for the three rock materials representing the true material strain rate effect are also proposed.

Physical and chemical determinants of colloid transport and deposition in water-unsaturated sand and Yucca Mountain tuff material.

Colloid mobility was determined in a system consisting of quartz sand or crushed Yucca Mountain tuff, simulated groundwater (J-13), and hydrophilic latex particles. Water content (theta) and ionic strength (I; DI water, 0.1x, 1x, 10x groundwater dilution) were manipulated to define limiting conditions for colloid transport atthe Yucca Mountain site. Colloid transport, measured with a centrifuge method at relatively high theta (saturation >36% for sand, >62% for crushed tuff) in DI water, was equivalent to transport at 100% saturation measured with conventional columns. When variables were isolated, increasing I and decreasing theta resulted in a greater extent of colloid deposition; I was more important at higher theta; physical properties were more important at lower theta. I and theta had an interactive effect on colloid deposition whereby synergism was generally observed, especially for simulated groundwater (1x); antagonism was observed at 10x groundwater dilution. At 19% moisture saturation on the crushed tuff, a decreasing rate of colloid deposition was observed. This corresponded to a hydrodynamic condition of 79% immobile water where solute tracers were excluded from a fraction of the pore volume. This suggests that a portion of the favorable sites for deposition were associated with the excluded or immobile water domain and were not accessible to colloids.

Binary and Ternary Ion-Exchange Equilibria in Zeolitized Tuff: Cs-Sr-Co System

Abstract Sorption isotherms for the ternary system Cs-Sr-Co using ‘Nonscents,’ a zeolitized volcanic tuff material from southeast Arizona, as sorbent were measured with a columnar flow technique. The isotherms were correlated with an ion-exchange phase-equilibrium model, and the triangle rule of ion exchange has been validated. Sorbent-phase selectivity for the ternary system has been successfully predicted from a knowledge of the selectivity of constituent binary pairs. The study helps in the understanding of multisolute sorption behavior during host rockground water interactions relevant to a high-level nuclear waste repository.