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When present at elevated levels in drinking water, arsenic is toxic, and magnesian clays are gaining recognition as a source of elevated arsenic in groundwater. In the crust and upper mantle of Earth, arsenic incorporation into clay minerals is influenced by geochemical conditions associated with hydrothermal fluids and metamorphic processes (e.g. serpentinization), meaning that As is a useful tracer of fluid-flow in the deep Earth. To improve understanding of arsenic speciation in groundwater, sediments, soils, and hydrothermal-metamorphic systems, the present study examined arsenic incorporation into magnesian clays by synthesis of serpentine minerals (200oC, 10 d) with varied concentrations of Si, Al, As5+, and As3+. The synthesis experiments produced two distinct crystal types, tubular and platy serpentines, each with 10–15% randomly interstratified talc layers. X-ray absorption spectroscopy indicated that As5+ and As3+ occurred in the tetrahedral sheet. Single-crystal analysis revealed that tubular crystals contained up to 1 wt.% arsenic [Mg2.8(Si1.8As0.2)O5(OH)4] (mean 0.2 wt.% As). The mean composition of platy, high-Al crystals is (Mg1.8Al0.7)(Si2.0)O5(OH)4, and that of platy, medium-Al crystals with As3+ is (Mg2.07Al0.52) (Si1.97As3+0.03)O5(OH)4. Charge, geometry, and radius of tetrahedral AsO43– oxyanions are similar to tetrahedral SiO44–, and this facilitates fixation of As5+ into the tetrahedral sheet of clay minerals. The geometry and size of the larger As3+ in tetrahedral sites (as a pyramidal AsO33– oxyanion) may limit incorporation relative to As5+. Arsenic-bearing Mg clays crystallize in alkaline environments where AsO43– or AsO33– are the dominant As species and where high pH accompanies crystallization of serpentine, talc, chlorite, or Mg-smectite. The presence of tetrahedral As in these clays raises the possibility of tetrahedral As in other Mg clays (e.g. sepiolite or kerolite) as well.

Tropical soils exhibit large differences across landscapes in many attributes, notably clay mineralogy (2:1 vs. 1:1 clays), bulk geochemistry (Ca, Al), pH, cation exchange capacity (CEC), organic matter and soil texture. In order to examine the factors controlling these variables, a series of three chronosequences (≤ 120 ka) of tropical soils on uplifted terraces along the Pacific coast of Costa Rica were studied. The three study locations differ mainly as a function of soil moisture and leaching, with conditions ranging from 2700 mm/yr mean annual precipitation (MAP) on the southern Nicoya Peninsula (4-month dry season), to 3200 mm/yr in the Esterillos region (3-month dry season), and 4250 mm/yr on the Osa Peninsula (no dry season). Analytical methods include X-ray diffraction (XRD), transmission-analytical electron microscopy (TEM-AEM), inductively coupled plasma optical emission and mass spectrometry (ICP-OES, ICP-MS), ammonium acetate extraction (1 M NH4OAc, pH = 7, for CEC) and C:N analysis. Soil weathering reactions and related decrease in CEC occur three-to-four times faster in a sequence of Inceptisol-to-Oxisol soils in the wettest climate (Osa) compared to the less-moist Esterillos area; in the even drier monsoon climate soils (Nicoya), this evolved, low-CEC ( The age-related evolution of tropical soils appears to be a predictable sequence in lowland tropical landscapes where periodic tectonism, erosion or volcanism produces unweathered parent material at the land surface. Empirical data from this project enables the extrapolation of simple equations applicable to tropical volcanic arc landscapes where presence of uplifted marine terrace soils facilitates determination of soil age. The two variables controlling soil composition can be combined into an effective age (ageeff) that takes into account soil age and weathering intensity (factoring in MAP and wet-dry months from climate data), and equations are of the form, e.g. ECEC = − 18.1 ∗ ln(ageeff) + 77, with R2 values of 0.75 to 0.87. Greatest scatter occurs in the youngest soils. Given the apparent prevalence of this sequence and the systematic nature of its reaction progression, these results could be useful for modeling tropical soils.

This project investigated the origin of clay minerals in regolith present above quartzite bedrock in the alpine zone of the Uinta Mountains, Utah, USA. Geochemical and mineralogical analysis indicates that these clays formed through chemical weathering of two allochthonous parent materials. Smectite-rich clays, with Mg abundance distinctly higher than modern dust or local bedrock, formed through weathering of andesitic ash layers that were deposited during the Oligocene from eruptive centers in the Basin and Range. In contrast, various stages of interstratified kaolinite-illite–smectite clays have formed through weathering of mica and feldspar delivered by eolian processes that continue today. Local bedrock appears to have played only a minor role as a parent material for clay neoformation. These results demonstrate that pedogenic clay can be common even in cold climate soils and regolith overlying weathering resistant bedrock. They also emphasize that the clay inventory in soil and regolith can reflect processes that operated before modern climatic conditions were established, and reinforce the key role played by exogenous mineral inputs in the functioning of the alpine critical zone.

Stream water pH and composition are widely used to monitor ongoing recovery from the deposition of strong anthropogenic acids in many forested headwater catchments in the northeastern United States. However, stream water composition is a function of highly complex and coupled processes, flowpaths, and variations in soil and bedrock composition. Spatial heterogeneity is especially pronounced in headwater catchments with steep topography, potentially limiting stream water composition as an indicator of changes in critical zone (CZ) dynamics during system recovery. To investigate the link between catchment characteristics, landscape position, and stream water composition we used long-term data (1991–2015) from the Sleepers River Research Watershed (SRRW) in northeastern Vermont. We investigated trends with time in stream water and trends with time, depth, and landscape position (upslope, midslope, and riparian zone) in groundwater (GW) and soil solution. We further determined soil elemental composition and mineralogy on archived (1996) and modern (2017) soil samples to assess changes in composition with time. SRRW is inherently well-buffered by calcite in bedrock and till, but soils had become acidified and are now recovering from acidification. Although base cations, especially Ca, decrease progressively with time in GW, riparian soils have become more enriched in Ca, due to a mixture of lateral and vertical transfers. At the same time stream water Ca fluxes increased over the past two decades, likely due to the leaching of (transient) legacy Ca from riparian zones and increased water fluxes. The stream water response therefore reflects the dynamic changes in soil chemistry, flow routing and water inputs.

Tropical soils range from nutrient-depleted lateritic soils rich in halloysite or kaolinite to Inceptisols rich in interstratified kaolinite-smectite (K-S), smectite, or related 2:1 clays. Given the strong influence of clay minerals on tropical soil quality, better understanding of factors influencing their occurrence is important for modeling and managing tropical environments. This study examines the alteration of smectite to kaolinite by way of intermediate K-S and halloysite in a 120 ka moist tropical chronosequence. Iron-rich smectite (11.6 ± 2.2% Fe2O3) is the dominant mineral in Holocene soils (1–8 ka) originating from sediments rich in plagioclase and clinopyroxene. The cation exchange capacity (CEC) of smectite is 54–84 cmolc/kg and pH is 6.1 to 7.4. Within 50 ka, smectite fixes Al-hydroxy complexes into interlayers, K+ is retained preferentially over Ca2+, and 2:1 layers are stripped of tetrahedral sheets; the resulting K-S inherits flaky smectite crystal habit and the 2:1 layers — which only expand partially — include Al-hydroxy smectite and some illite-like layers. After 50 ka, the dominant mineral is K-S, the CEC is 18–28 cmolc/kg, and the pH is 5.3. Flaky Fe-kaolinite with ~10% residual smectite layers and halloysite (7.4% Fe2O3) also occur in 50 ka soil. The 120 ka soils are dominated by flaky Fe-kaolinite (

Profiles of alpine soils in the Uinta Mountains (Utah, USA) were investigated to determine how long-term dust deposition has influenced soil properties in this environment. Field studies were focused on four above-treeline sites, all of which were apparently beyond the reach of erosive glacial ice during the Pleistocene. Modern dust, soil A and B horizons, and local bedrock were compared in terms of major and trace element geochemistry, along with Sr and Nd isotope compositions. In all cases, soil samples are a mixture of dust and local bedrock end members, with A horizons more closely resembling dust, and B horizons more similar to bedrock. Calculations estimate that these soil profiles contain ~50 to 80% dust, which is effectively mixed downward into the solum by cryoturbation. Because these landscape positions were not glaciated, the total amount of dust contained within soil profiles is large relative to sites at lower elevation within the glacial limit. In addition to altering physical properties of these soil profiles, including horizonation and texture, deposition of dust rich in base cations positively influences soil fertility.

Arsenic-bearing pyrite is the source of arsenic in groundwater produced in late Cambrian and Ordovician gray and black slates and phyllites in the Taconic region of southwestern Vermont, USA. The aim of this study is to analyze the sulfur isotopic composition of this pyrite and determine if a relationship exists between pyrite δ 34 S and arsenic content. Pyrite occurs in both sedimentary/diagenetic (bedding-parallel layers and framboids) and low-grade metamorphic (porphyroblast) forms, and contains up to > 2000 ppm As. The sulfur isotopic composition of arsenic-bearing pyrite ranges from − 5.2‰ to 63‰. In the marine environment, the sulfur in sedimentary pyrite becomes increasingly enriched in 34 S as the geochemical environment becomes increasingly anoxic. There is a positive correlation between δ 34 S and arsenic content in the Taconic pyrite, suggesting that uptake of arsenic by pyrite increased as the environment became more reducing. This increased anoxia may have been due to a rise in sea level and/or tectonic activity during the late Cambrian and Ordovician. Low-grade metamorphism appears to have little effect on sulfur isotope composition, but does correlate with lower arsenic content in pyrite. New groundwater wells drilled in this region should therefore avoid gray and black slates and phyllites that contain sedimentary/diagenetic pyrite with heavy δ 34 S values.

Elevated As levels have been reported by the Vermont Geological Survey in groundwater from public and domestic bedrock wells in northwestern New England (USA). The study area in southwestern Vermont is underlain by pyrite-rich, organic-rich slates that were thrusted over carbonate and clastic sedimentary rocks of the continental shelf during the Ordovician Taconian Orogeny, and the distribution of wells with elevated As shows that they were completed in slates. Hydrochemical and bedrock geochemical analysis indicates that elevated As in the aquifer system is controlled by the following: (1) the presence of black slates that are rich in arsenian pyrite (200–2000 ppm As); (2) release of As via the dissolution of As-rich pyrite; (3) geochemically-reducing and slightly alkaline conditions, where high As values occur at Eh 7; and (4) physical hydrogeological parameters that foster low Eh and high pH, particularly long groundwater flow paths and low well yields (i.e. high residence time) which provides high rock to water ratios. Where all four factors affect As contents in groundwater, 72% of wells in a zone of distal groundwater flow/low-relief topography exceed 10 μg/L (ppb) and 60% of wells in this zone exceed 25 ppb As. Where flow paths are shorter in slates and groundwater has higher Eh and lower pH (i.e. in regions of higher-relief topography closer to recharge zones), only 3% of wells contain >10 ppb As and none contain >25 ppb. Overall, 28% (50/176) of low-elevation wells (

In 2000, elevated nitrate concentrations ranging from 12 to 34mg/L NO3N were discovered in groundwater from numerous domestic bedrock wells adjacent to a large dairy farm in central Vermont. Long-term plots and contours of nitrate vs. time for bedrock wells showed "little/no", "moderate", and "large" change patterns that were spatially separable. The metasedimentary bedrock aquifer is strongly anisotropic and groundwater flow is controlled by fractures, bedding/foliation, and basins and ridges in the bedrock surface. Integration of the nitrate concentration vs. time data and the physical and chemical aquifer characterization suggest two nitrate sources: a point source emanating from a waste ravine and a non-point source that encompasses the surrounding fields. Once removed, the point source of NO3 (manure deposited in a ravine) was exhausted and NO3 dropped from 34mg/L to10mg/L after ~10years; however, persistence of NO3 in the 3 to 8mg/L range (background) reflects the long term flux of nitrates from nutrients applied to the farm fields surrounding the ravine over the years predating and including this study. Inferred groundwater flow rates from the waste ravine to either moderate change wells in basin 2 or to the shallow bedrock zone beneath the large change wells are 0.05m/day, well within published bedrock aquifer flow rates. Enrichment of (15)N and (18)O in nitrate is consistent with lithotrophic denitrification of NO3 in the presence of dissolved Mn and Fe. Once the ravine point-source was removed, denitrification and dilution collectively were responsible for the down-gradient decrease of nitrate in this bedrock aquifer. Denitrification was most influential when NO3N was10mg/L. Our multidisciplinary methods of aquifer characterization are applicable to groundwater contamination in any complexly-deformed and metamorphosed bedrock aquifer.

In the fractured bedrock aquifer of northern Vermont, USA, As concentrations in groundwater range from

Fe-rich kaolins in soils of a terrace chronosequence in the moist tropics of Costa Rica are derived from the transformation of smectite via interstratified kaolin–smectite (K–S). The smectite is ferruginous smectite (10.1 ± 3.7% Fe2O3) that forms early during pedogenesis from basaltic–andesitic parent material and is the dominant mineral in 80% kaolin layers. K–S is indicated by X-ray diffraction (XRD) data that reveal asymmetric 001 peaks between 17.5 and 17.8 A (ethylene glycol-solvated) and irrational 00l peaks that exhibit Mering-like behaviour, and by transmission electron microscopy–analytical electron microscopy (TEM–AEM) data that document single crystals of K–S with compositions intermediate to those of end-member crystals of smectite and kaolin. Lattice fringe images from high resolution TEM (HRTEM) show lateral transitions from smectite layers to kaolin layers via a cell-preserved, layer-by-layer transformation mechanism, and changes in the compositions of tetrahedral and octahedral sheets, notably decreases in octahedral Fe and Mg and tetrahedral Al, indicate that the reaction is accompanied by localized dissolution of smectite 2:1 layers that proceeds laterally. Fourier transform infrared (FTIR) and XRD data indicate that kaolin layers are a mixture of kaolinite and halloysite, and differential thermal analysis–thermogravimetry (DTA–TG) combined with data from XRD and TEM–AEM indicate the development of Al-hydroxy-interlayers in K–S with time. The soil-forming factors that appear to control formation of K–S are (1) basaltic–andesitic parent that produces high concentrations of base cations and Si in young (

We compared the elemental composition of soil and bedrock samples to determine the extent of chemical weathering and the nature of the soil parent material in alpine soils on Vermont's highest summit. Previously it was unclear whether these soils formed through weathering of bedrock, glacial till, or eolian sediment, or solely through the accumulation of organic matter. In eighteen profiles, no evidence was found to indicate that soils have developed in glacial till, despite evidence that the mountain was completely inundated by the Laurentide Ice Sheet. In contrast, results strongly support the theory that pedogenesis in this environment involves in situ bedrock weathering under a thickening blanket of acidic organic litter. Weathering indices reveal an increase in weathering intensity upwards from the bedrock, and trends of normalized rare earth elements demonstrate a strong similarity between bedrock and soil samples. Leaching has concentrated less mobile elements such as Al, Cr, La, P, Pb, and Ti in soil horizons and removed mobile elements such as Co, Fe, K, Mg, Mn, Si, and Zn. X-ray diffraction reveals that chlorite, which is present in all bedrock samples and some saprolites, has weathered completely from upper soil horizons, and that hydrobiotite, vermiculite, kaolinite, gibbsite, and goethite have formed in the soil. Ratios of immobile elements (Ce, Cr, Nb, Ta, Ti, Y, and Zr) in soil and bedrock samples are, however, notably different. Furthermore, the moderately mobile trace elements Cu, Mo, and Sr are actually more abundant in soil than in bedrock, and soil concentrations of Zr are up to an order-of-magnitude greater than in bedrock samples. Together these data argue for at least a modest eolian influx, which may have arrived during the regression of Lake Vermont during the latest Pleistocene or from an outwash source in the immediate post-glacial period. Similarly, increased Ca and Na concentrations in soil samples may signify modern deposition of dust bearing Ca (from agricultural fields) and Na (from roads).

Soils developed on Quaternary fluvial fill terraces in the humid tropics of Costa Rica display progressive changes in mineral assemblage, chemical composition and particle size with age. Clay minerals from B horizons of active floodplains are predominantly smectite with lesser amounts of disordered kaolinite. B horizons in 5 to 10 ka soils consist of sub-equal amounts of smectite and disordered kaolinite, and soils on 37–125 ka terraces consist of disordered kaolinite with only traces of smectite. The composition of the smectite, as determined by EDX scans of smectite-rich pore space, is [(Mg0.2,Ca0.1)(Fe0.6Al1.4)(Si3.6Al0.4)O10(OH)2], consistent with ferruginous beidellite. Bulk mineral assemblage varies from a smectite-plagioclase-augite-quartz-magnetite assemblage in ⩽10 ka terrace soils to a disordered kaolinite-goethite-hematite-quartz-magnetite assemblage in ⩾37 ka terrace soils. Leaching results in rapid loss of soluble base cations and residual concentration of Ti and Zr indicates mass losses of ~50% by chemical denudation by 125 ka. Plots of terrace age vs. various measures of clay mineralogy, chemical composition, and particle size produce parabolic curves consistent with rapid chemical weathering pre-37 ka and slower to imperceptible rates of change from 37 to 125 ka. For some pedogenic properties, particularly particle size and concentrations of base cations and Zr, soils appear to reach steady-state conditions within 37 ka. These results were applied to interpretation of landscape evolution in this tectonically active region by: (1) facilitating identification of two Holocene (5 ka and 10 ka) terraces on the Esterillos Block 5–30 m above sea level (masl), and two Pleistocene terraces ⩾125 ka on the Parrita Block 30 masl, and, in turn, (2) documenting uplift rates as high as 4.4 m/ka between 37 and 10 ka on the Esterillos Block, and as low as 0.1 m/ka over the past 125 ka on the adjacent Parrita Block. These findings are consistent with previous work indicating that the subduction of anomalous bathymetric features at the Middle America Trench is having a significant impact on fore-arc dynamics and topography over relatively short geological time periods and spatial scales.

Soils developed on Pleistocene andesitic lava flows and fluvial detritus in the Atlantic coastal plain of Costa Rica display a clay mineral assemblage that includes 10 A and 7 A halloysite and lesser amounts of kaolinite and dioctahedral vermiculite. Other secondary minerals include gibbsite, goethite, hematite, maghemite, allophane and amorphous Al hydroxides. Active floodplain soils are dominated by 10 A halloysite and contain less allophane, while soil clays from Pleistocene terraces consist of a mixture of 10 A and 7 A halloysite as well as less dioctahedral vermiculite, kaolinite, and amorphous Al hydroxides. Residual soils formed on Pleistocene lava flows are dominated by 7 A halloysite with less abundant kaolinite, dioctahedral vermiculite, 10 A halloysite and amorphous Al hydroxides. This sequence suggests transformations of 10 A halloysite to 7 A halloysite and allophane to amorphous Al hydroxides with time. The presence of 10 A halloysite in Pleistocene terrace soils implies slow reaction rates or metastability. Quantitative X-ray diffraction (QXRD) analysis indicates a decrease in the amount of plagioclase feldspar from 34 wt.% in the 1–2 year floodplain to 0–1.6% in terrace and residual soils. Plagioclase weathering is paralleled by the formation of dioctahedral clay, allophane and Al hydroxides. Analysis by QXRD also indicates that crystalline minerals comprise 70–95% of the soil fraction, implying 5–30% X-ray-amorphous material. These data are verified by selective extraction using ammonium oxalate, which indicates 8–30% amorphous material. Chemical analysis of the extractant by inductively coupled plasma-atomic emission spectrometry indicates that allophane (Al:Si ratios of 0.92–3.82) occurs in floodplain and some terrace soils while amorphous Al hydroxides appear to coexist with allophane in Pleistocene terrace and residual soils with Al:Si ratios of 6.53–8.53. Retention of Mg to a greater extent than Na, Ca and K suggests Mg incorporation into hydroxide sheets in dioctahedral vermiculite as well as substitution into hydroxides.

Late Jurassic sandstones of the shallow-marine Sundance Formation contain authigenic chlorite minerals that occur as rosette-like pore fillings of interstratified berthierine/chamosite (B-C) and honeycomb-like pore linings of corrensite and discrete chlorite. B-C is nearly ubiquitous in Sundance sandstones, but is absent near the top of the formation, whereas corrensite and discrete chlorite were detected only in uppermost Sundance sandstones, within 4 m of the contact with the overlying non-marine Morrison Formation. Glauconite grains are common and occur as laminae along bedding planes and cross-beds, indicating reworking and deposition as clasts in tidally influenced regimes. The mineralogical, chemical, and morphological properties of the B-C and corrensite indicate that they are authigenic and formed during burial diagenesis from precursor minerals, odinite in the case of B-C, and saponite in the case of corrensite and discrete chlorite. Odinite has been recognized in numerous shallow-marine sands of the Holocene verdine facies, and the shallow-marine conditions associated with Sundance deposition would have been ideal for odinite formation. Saponite commonly forms in aeolian and evaporitic environments, implying that the saponite precursor to corrensite and discrete chlorite formed in uppermost Sundance sands that were exposed to an influx of oxidizing groundwater following regression of the Sundance sea. X-ray diffraction (XRD) indicates that the proportion of 7 A B layers in B-C ranges from 5 to 28%, and chemical analysis by scanning electron microscope-energy dispersive X-ray spectrometry (SEM-EDS) indicates positive correlation between %B and Fe/(Fe + Mg). The polytype of the B-C is Ibb , and the corrensite and discrete chlorite are disordered IIb . These are the expected polytypes and %B for sandstones exposed to burial diagenetic conditions of 3000–4000 m and temperatures 90–120 °C.

X-ray powder diffraction patterns of halloysite (7 Å) are characteristically altered following solvation with ethylene glycol. Some effect was first noted in the classic work of MacEwan but its value in the unequivocal identification of halloysite (7 Å ) seems to have been overlooked subsequently. The response to ethylene glycol solvation involves a decrease in the intensity (peak height) of the peak at ∼7.2 Å and an increase in the intensity (peak height) of the peak at ∼3.58 Å thus narrowing the 7.2 Å /3.58 Å peak height intensity ratio. For pure samples of halloysite, this ratio is narrowed by an average of ∼50%. This distinctive change is related to the interstratified nature of halloysite (7 Å), specifically the presence of ‘residual’ interlayer water, i.e. halloysite (10 Å), which can be replaced with ethylene glycol so forming 10.9 Å layers, a spacing that is almost exactly one and a half times the thickness of dehydrated (7.2 Å) layers which do not imbibe ethylene glycol. Thus the separation between the 001 peaks in the 7.2 Å /10.9 Å interstratification is increased and the 0027.2(3.58 Å) and 00310.9(3.63 Å) peaks become more or less coincident, compared to the 7.2 Å /10 Å interstratification, i.e. the partially hydrated state. The widespread use of ethylene glycol solvation in clay mineral studies makes it a particularly useful and simple test to determine the presence of halloysite. Pure halloysites should be readily identifiable and experiments indicate a ‘routine’ sensitivity of ∼20% halloysite in mixtures with kaolinite, although this will depend on factors such as ‘crystallinity’ and could be improved with careful attention to intensity measurements. It is proposed to call this phenomenon the ‘MacEwan effect’ in honour of its discoverer Douglas Maclean Clark MacEwan.

Sequential chemical extraction (SCE) and quantitative X-ray diffraction (QXRD) were used in combination to assess trace metal speciation and availability in sediment from two separate marshes in western Vermont, USA, one with high (45%) and one with low (

Elevated As occurs in many meta-sedimentary bedrock aquifers where elevated bulk-rock As content is one of the primary controls on the concentration of As in groundwater. This study was designed to determine As concentrations in a black shale, black slate and black phyllite sequence that comprises the bedrock aquifer system of the Taconic Mountain region of southwestern Vermont and adjacent New York State. Variability in groundwater As concentrations provides the impetus for this study: 25% of wells in weakly metamorphosed shales and slates (

The chemical composition of mixed-layer serpentine/chlorite (Sp/Ch) in Tuscaloosa Formation sandstone was analyzed by energy dispersive X-ray spectroscopy (EDX) in the scanning electron miscro- scope (SEM) and by X-ray diffraction (XRD). EDX results indicate little depth-controlled variation in composition, whereas XRD results suggest distinct decreases in octahedral Fe and tetrahedral A1. XRD- determined compositions appear to be erroneous and actually reflect progressive changes in Sp/Ch unit- cell dimensions caused by polytype transformations of Ibb layers to Iaa layers in a mixed-layer IbblIaa polytype. The relative lack of variation in Sp/Ch composition, especially when compared to other studies of chlorite minerals over similar temperature ranges, is attributed to a reaction mechanism whereby mineralogic transformations (serpentine layers to chlorite layers and Ibb layers to Iaa layers) occur on a layer-by-layer basis within coherent crystallites, rather than by dissolution-precipitation crystal growth. The lack of titanium in chlorite minerals is attributed to high levels of octahedral A13§ that prohibit inclusion of the highly charged Ti 4+ in the octahedral sheet. Anatase (TiO2) in the Tuscaloosa Formation apparently formed when Ti was liberated during crystallization of Sp/Ch following !he breakdown of a Ti-bearing precursor (detrital ultramafic clasts and/or odinite). Odinite, an Fe-rich 7-A phyllosilicate that forms in some shallow marine sands, apparently existed as a short-lived, poorly crystallized intermediary between dissolution of the ultramafic clasts and formation of Sp/Ch.

Sequential extraction procedures (SEPs) are commonly used to determine speciation of trace metals in soils and sediments. However, the non-selectivity of reagents for targeted phases has remained a lingering concern. Furthermore, potentially reactive phases such as phyllosilicate clay minerals often contain trace metals in structural sites, and their reactivity has not been quantified. Accordingly, the objective of this study is to analyze the behavior of trace metal-bearing clay minerals exposed to the revised BCR 3-step plus aqua regia SEP. Mineral quantification based on stoichiometric analysis and quantitative powder X-ray diffraction (XRD) documents progressive dissolution of chlorite (CCa-2 ripidolite) and two varieties of smectite (SapCa-2 saponite and SWa-1 nontronite) during steps 1-3 of the BCR procedure. In total, 8 (+/-1) % of ripidolite, 19 (+/-1) % of saponite, and 19 (+/-3) % of nontronite (% mineral mass) dissolved during extractions assumed by many researchers to release trace metals from exchange sites, carbonates, hydroxides, sulfides and organic matter. For all three reference clays, release of Ni into solution is correlated with clay dissolution. Hydrolysis of relatively weak Mg-O bonds (362 kJ/mol) during all stages, reduction of Fe(III) during hydroxylamine hydrochloride extraction and oxidation of Fe(II) during hydrogen peroxide extraction are the main reasons for clay mineral dissolution. These findings underscore the need for precise mineral quantification when using SEPs to understand the origin/partitioning of trace metals with solid phases.

A K-bentonite in the Middle Carbonate Group of the Belt Supergroup is evidence for eruptive volcanic activity within or adjacent to the Belt basin during Middle Proterozoic deposition. The texture of this olive-green rock is dominated by a fine-grained groundmass similar to Paleozoic K-bentonites. Throughout this groundmass are a few randomly occurring angular, irregularly shaped clasts composed of quartz. The morphology of these clasts indicates the quartz grains have not been transported. Traces of small euhedral zircons are also present. The mineralogy and chemical composition of the groundmass in this K-bentonite is also similar to Paleozoic K-bentonites but appears to reflect a more evolved mineralogy as a result of its age and thermal history. Unlike Paleozoic K.bentonites, whic are characteristically the 1M polytype, authigenic 1M and 2M1 illite/mica polytypes coexist in this Proterozoic K-bentonite and are separable by size fractionation. The K.Ar ages of the clay fractions range from 807 Ma in the coarser fraction to 606 Ma in the finer fraction. The 807 Ma K-Ar age of 2M1 mica indicates temperatures in excess of 250°C during this time. The 606 Ma K-AT age of the fine-grained 1M polytype probably reflects later 1M crystallization at temperatures below 250°C. The reaction of 1M to 2M1 polytype in this K-bentonite did not require major changes in chemical composition, and the dominant controls on the 1M to 2M1 polytype transformation appear to have been temperature and time.

Endometriosis involving the kidneys is rare. To our knowledge we report the first case in which kidney involvement was the initial manifestation of this condition. Because of previous bilateral oophorectomy the diagnosis of endometriosis was improbable. Hormone replacement therapy was implicated in the etiology.

Testicular torsion patients have significant fertility problems, which may be due to bilateral testicular disease. This study was designed to define expression of spermatozoal alloantigens and autoantigens on rat spermatozoa by immunization experiments and highly sensitive immunological techniques, and then determine whether or not experimental torsion results in autoimmunization. Sperm protein alloimmunization and autoimmunization experiments were first performed. Later, experimental torsions were applied for periods from 1 h to permanent torsion and also torsion followed by orchidectomy. Sera from these animals were then tested and compared to controls for evidence of immunological activation. Immunoblotting and dot ELISA tests demonstrated spermatozoal autoantigens following intradermal immunization and that experimental torsion is followed by a rising titre of sperm protein autoantibodies. The possible consequences of these findings are discussed.

The advantages and disadvantages of piezoelectric lithotripsy are discussed with specific analysis of the EDAP LTO1. A description of the EDAP LTO1 is included, including its imaging properties and the physics of piezoelectric transduction. Installation, accommodation, and maintenance features are discussed. A total of 118 patients had 158 treatments for 134 renal and 24 ureteric calculi. Failure of imaging or fragmentation occurred in 3.9% of renal calculi and 33.3% of ureteric calculi. Six staghorn calculi were treated with a mean clearance at 3 months of 83.6%. The majority (68.8%) of patients with ureteric calculi had successful treatments with the stone pushed into the kidney before ESWL.

An experimental model of ureteric obstruction should be accurate and persistent, and allow variation of the degree of obstruction. A model was tested in 28 dogs consisting of insertion of an obstructing stent into the left ureter, and the degree of obstruction was varied by altering the internal diameter of the stents. The effects of such an obstruction on the following features were studied: renal intrapelvic pressure, intravenous urography, creatinine clearance, vascular casts, and both gross and histological examination. The procedure was well tolerated and caused a persistent, unchanging degree of partial ureteric obstruction. Pathological changes of obstructive uropathy were produced. This model can be used for further pathophysiological studies.

The advantages and disadvantages of piezoelectric lithotripsy are discussed with specific analysis of the EDAP LT01. A description of the EDAP LT01 is included, as well as its imaging properties and the physics of piezoelectric transduction. Installation, accommodation, and maintenance features are discussed. A total of 118 patients had 158 treatments for 134 renal and 24 ureteric calculi. Failure of imaging or fragmentation occurred in 3.9% of renal calculi and 33.3% of ureteric calculi. Six staghorn calculi were treated with a mean clearance at three months of 83.6%. The majority (68.8%) of ureteric calculi had successful treatments with the stone pushed into the kidney before treatment with extracorporeal shock wave lithotripsy (ESWL).