Widmanstaetten patterns in josephinite, a metal-bearing terrestrial rock

Widmanstaetten patterns have been found in several specimens of josephinite, a complex, metamorphosed, metal-bearing rock from placers on serpentinized peridotite in southwest Oregon. The patterns, in interior less-altered regions of the specimens, are typical of exsolution textures produced during slow cooling of a homogeneous metal. The bulk composition of the metal phases indicates that the homogeneous metal must have existed at temperatures above 500 degrees C. Josephinite Widmanstaetten patterns are the first known in terrestrial rock. We interpret them as further evidence that josephinite was derived from the mantle.     

Longitudinal trends in pH and aluminum chemistry of the Coxing Kill,Ulster County,New York

The purpose of this work was to characterize the Al chemistry along the longitudinal pH gradient of the Coxing Kill and thereby provide a basis for an in depth study of aluminum chemistry and transport as a function of pH. Water samples were collected along the pH gradient and analyzed for monomeric Al species, strong acid anions, base cations, ammonium, dissolved organic C and dissolved silica. Inorganic monomeric Al, organic momonmeric Al and dissolved organic C decreased in concentration as the stream's drainage area and pH increased. The ratio of organic to inorganic monomeric Al and the concentration of all other species increased with increasing pH. An abrupt change in stream chemistry occurred in conjunction with the gradual changes expected for a low order stream draining an acid sensitive watershed impacted by acid deposition. This abrupt change partially resulted from geological characteristics of the watershed.     

A Comparison of Two Collectors for Monitoring Precipitation Chemistry

Comparison of event-based precipitation collected during 1 year showed that samples from a Yankee Environmental Systems collector had significantly higher volume, higher concentrations, and higher deposition of all ions analyzed except PO₄³⁻ and NH₄⁺ compared to samples collected simultaneously with an Aerochem Metrics collector.     

Determination of Sulfate,Nitrate, and Chloride in Throughfall using Ion-Exchange Resins

Throughfall, the solution that falls from the forest canopy, is an important and commonly measured flux in forest ecosystem studies. Throughfall water and chemistry are highly variable spatially, requiring large numbers of collectors to quantify it. This and the fact that the solution can be chemically unstable make throughfall sampling very labor intensive, thus we have developed a method to reduce the field labor portion of this effort. Our throughfall collection method uses compact ion exchange resin columns that need only be collected every 1–2 months. The resin columns are subsequently extracted with 1.0 M potassium iodide (KI), releasing anions back into solution, with extraction efficiencies > 94% for sulfate, nitrate, and chloride. The extracts are analyzed by ion-chromatography (IC) to determine the total microequivalents of anions per unit area of collector surface collected over the period of resin column exposure. This ion exchange resin method was originally developed for a project in which we needed to deploy over 300 throughfall collectors to quantify throughfall variability across mountainous terrain with heterogeneous vegetation.     

Catchment-Scale Variation in the Nitrate Concentrations of Groundwater Seeps in the Catskill Mountains,New York,U.S.A.

Forested headwater streams in the Catskill Mountains of New York show significant among-catchment variability in mean annual nitrate (NO₃ ^-) concentrations. Large contributions from deep groundwater with high NO₃ ^-concentrations have been invoked to explain high NO₃ ^-concentrations in stream water during the growing season. To determine whether variable contributions of groundwater couldexplain among-catchment differences in streamwater, we measuredNO₃ ^- concentrations in 58 groundwater seeps distributed across six catchments known to have different annual average streamwater concentrations. Seeps were identified based on release from bedrock fractures and beddingplanes and had consistently lower temperatures than adjacentstreamwaters. Nitrate concentrations in seeps ranged from neardetection limits (0.005 mg NO₃ ^--N/L) to 0.75 mg NO₃ ^--N/L. Within individual catchments, groundwaterresidence time does not seem to strongly affect NO₃ ^-concentrations because in three out of four catchments therewere non-significant correlations between seep silica (SiO₂) concentrations, a proxy for residence time, andseep NO₃ ^- concentrations. Across catchments, therewas a significant but weak negative relationship betweenNO₃ ^- and SiO₂ concentrations. The large rangein NO₃ ^- concentrations of seeps across catchmentssuggests: 1) the principal process generating among-catchmentdifferences in streamwater NO₃ ^- concentrations mustinfluence water before it enters the groundwater flow system and 2) this process must act at large spatial scales becauseamong-catchment variability is much greater than intra-catchmentvariability. Differences in the quantity of groundwater contribution to stream baseflow are not sufficient to account for differences in streamwater NO₃ ^- concentrationsamong catchments in the Catskill Mountains.     

Differences between new england coastal fog and mountain cloud water chemistry

Major inorganic ions and pH were analyzed from mountain cloud and coastal fog water event samples from New Hampshire and Maine, U.S.A. Based on marine corrected values, the medians for coastal fog were still up to three times higher in ionic concentrations and lower in pH, compared to mountain clouds. Of the acidic constituents, nitrate concentrations were considerably higher in coastal fogs, which correlates with higher concentrations of 03 measured along the New England coast. It is hypothesized that meteorological conditions permit air pollutants emitted in the northeastern US urban corridor to move relatively intact across the Gulf of Maine and to interact with the coastal fogs, which results in differences in the chemistry of coastal fogs and mountain clouds.     

检测植物病毒的三种血清学方法敏感性的比较

 以芋花叶病毒和豇豆花叶病毒为试验材料,进行了酶联免疫吸附试验,免疫吸附电子显微术和点免疫结合试验检测植物病毒的敏感性的研究。无论是检测感染组织粗汁液还是纯化的病毒,点免疫结合试验均优于酶联免疫吸附试验和免疫吸附电子显微术。在使用羟基吲(口乃木)磷酸盐和氮蓝四唑为碱性磷酸酶的底物时,点免疫结合试验检测纯化的豇豆花叶病毒的可测感度为0.35ng,芋花叶病毒为0.83ng。对三种检测植物病毒的血清学方法进行了比较,并讨论了点免疫结合试验的优点。     

Melting of diamond

Radiation from a Q-switched YAG laser, focused on the (100) face of a single crystal diamond anvil in a high-pressure diamond cell, caused a portion of the diamond anvil face to melt. Potassium bromide mixed with graphite was under pressure between the anvils when melting occurred. The diamond surface melted at pressures greater than approximately 120 kilobars and graphitized at lower pressures. Evidence for the melting and graphitization of the diamond was obtained by optical and scanning electron microscopy.